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1 - ILO
m 51042 © Vth International Pneumoconiosis Conference V Conferencia Internacional de Neumoconiosis Caracas - Venezuela 29 October to 3 November 1978 Organized by Comité Nacional de Neumoconiosis International Labour Office Publisher: Wirtschaftsverlag NW, Verlag für neue Wissenschaft GmbH Am Alten Hafen 113-115, D-2850 Bremerhaven 1 Impressum: © 1985, International Labour Organization (ILO), Genf Gesamtherstellung: Wirtschaftsverlag NW, Verlag für neue Wissenschaft GmbH, Postfach 101110, D-2850 Bremerhaven 1, Tel. (04 71) 4 60 93-95 Printed in Germany 1985 ISBN 3-88314-264-9 Contents page Preface Prefacio 9 1 " SESSION I 1/1 J. A. Merchant Coalworkers'pneumoconiosis surveillance in the United States I/2 T. S. McLintock The prevalence of pneumoconiosis in British coal miners, 1959-1977 . . . I/3 G. Degueldre Epidemiologie des pneumoconioses dans les charbonnages de la campine belge I/4 A. Minette Peculiar aspects of the natural history of chronic bronchitis in coal miners I/5 M. Jacobsen Dust exposure and pneumoconiosis at 10 British coal mines 13 37 51 63 89 SESSION II 11/1 M. Adrianza Epidemiologia de la neumoconiosis en Venezuela II/2 B. Méndez An epidemiologic study of silicosis in Brazil, from a survey of patients in tuberculosis hospitals II/3 G. Cornea, A. Ghachem, A. Ben Kheder, Silvia Gabor, L. El Mekki La silicose dans une mine de spathfluor de Tunisie II/4 J. Prenafeta, G. Leyton M„ R. Sepulveda M. Variability in the X-ray diagnosis of early silicosis II/5 K. Chiyotani, Ken-ichi Saito Excess lung cancer risk in silicotic cases under hospital care preliminary report II/6 J. Prenafeta, A. Valenzuela, G. Leyton, S. Villagran Epidemiological survey and prognostic evaluation in silicosis 111 161 163 177 179 181 SESSION III III/1 B. Barhard L' évaluation du risque coniotique sur les lieux du travail 185 Hl/2 III/3 IM/4 III/5 111/© III/7 G. Cornea, A. Ghachem, A. Ben Kheder, M. Maalej, J. Daghfous, H. Bou-Acha, L. El Mekki La pneumoconiose dans une mine de fer de Tunisie: aspects radio-cliniques et fonctionnes 199 C. E. Rossiter, J. C. Wagner Man-made minerai fibres: Joint European medical research project . . . .209 D. F. Goldsmith, N. Stroup, J. F. Gamble, C. M. Shy Chronic lung disease in the furniture industry: An epidemiologic study design 219 M. L H. Flindt Pulmonary disease due to proteolytic enzymes 237 S. M. Rab, Zakaullah Beg, Abu Zafar Work-related diseases in Pakistan 249 C. Cornea, L. El Mekki, B. El Gharbi, A. Ben Kheder, Silvia Gabor Une nouvelle pneumoconiose végétale: le poumon de Neffa 251 SESSION IV IV/1 S. H. Zaidi Recent progress in etiopathogenesis of pneumoconioses IV/2 T. Sano, I. Ebihara Considerations on pathology, pathogenesis and etiology of pneumoconiosis IV/3 L. Le Bouffant, H. Daniel, J. C. Martin Nowite variable des poussières de silice selon leur origine: Influence de certains minéraux d'accompagnement IV/4 E. Quinot, C. Cavelier, M. O. Merceron Chimie de surface et cytotoxicité de silice IV/5 W. Weiler New aspects in the etiopathogenesis of silicotic and anthracosilicotic lesions IV/6 H. Hayashi Mineralogical analysis of lung dusts in pneumoconiosis with an analytical electron miscroscope 267 303 313 327 345 355 SESSION V V/1 V/2 V/3 M. Espinoza Neumoconiosis en el Peru 369 G. Mowé, Egil Phus, B. Gylseth Asbestos fibre content in lung tissue in relation to asbestos exposure and causes of death 383 N. V. Vallyathan, J. E. Craighead Silica dust-associated pulmonary lesions in granite workers lacking radiologic evidence of disease 397 V/4 J. A. Dick The role of pulmonary tuberculosis in the causation of progressive massive fibrosis in coal workers in Great Britain V/5 T. L Guidotti The higher oxides of nitrogen: A role in altering pulmonary response to injury V/6 J. Rosmanith, R. Leonardt, D. Prajsnar, H. Breining, W. Ehm The effect of the combined application of cadmium and lead sulfide and coal dust on the development of lung fibrosis in rats V77 D. Prajsnar, H. Breining, J. Rosmanith Lung fibrosis in rats after lead sulfide application V/8 H. Breining, J. Rosmanith, D. Prajsnar Lung fibrosis in rats after cadmium sulfide application 409 423 435 447 455 SESSION VI VI/1 Y. Hosoda, N. Saito, T. Kono, H. Ohtake, Y. Chiba Epidemiology of asbestos-induced pleural thickening 465 VI/2 M. L. Newhouse Asbestos-related diseases in relation to type of occupation 475 VI/3 Ruth Lilis, J. Selikoff Asbestos disease in maintenance workers of the chemical industry S. F. McCullagh Biological effects of asbestos-the unresolved matters W. Weiler Biological effects of asbestos-quartz dust-mixtures VI/4 VI/5 VI/6 . . . .479 501 511 L. M. Lacquet, L. Van der Linden, J. Lepoutre Prevalence of lung changes, and mortality in a Belgian asbestos-cement factory A. Hirsch, L Di Menza, M. Mangold, J. Bignon Rigidité diaphragmatique et exposition à l'amiante: correlation radiologique et chirurgicale dans 47 thoracotomies 555 VI/8 J. M. C. Davis, R. E. Bolton The pathological effects of asbestos cloud of different fibre dimensions on the lungs of rats 571 VI/7 525 SESSION VII VII/1 P. Sadoul, D. Teculescu Epreuves fonctionnelles dans le diagnostic précoce et la réadaptation des pneumoconioses 587 VII/2 L. Maldonado T, M. Martha Méndez, J. A. Legapsi V, A. Conzález Z. The value of studying pulmonary function with a view to the early diagnosis of silicosis 599 VII/3 K. Wilson, R. Richie, P. Stevens, B. Valley Effect of chronic amorphous silica exposure on sequential pulmonary function 609 VII/4 VII/5 P. García-Herreros, G. Scano, L. Stendarti, S. Degré, R. Sergysels, A. de Coster L'adaptation cardiopulmonaire à l'effort chez les mineurs de charbon J. E. Diem, R. N. Jones, J. C. Gilson, H. Glindmeyer, H. Weill The influence of asbestos exposure on radiographie progression and functional decline: A preliminary report 615 625 SESSION Vili VIII/1 VIII/2 VIM/3 VIII/4 VIII/5 VIM/6 VIM/7 VIII/8 VIM/9 W. T. Ulmer Biological and functional tests in early diagnosis of pneumoconiosis and rehabilitation M. Adrianza, C. Ernould, Y. Sanchez Pulmonary function of smoking workers esposed to inorganic dust . . . . Richard R. Martin, J. J. Gautheir, C. Bernard Exploration fonctionnelle dans le diagnostique précoce de l'asbestose . . K.Nobutomo Air pollution and cytological changes in sputum M. L. H. Flindt Identification of illness from allergenic dusts T. Mattsson, Matti S, Huuskonen, A. Zitting Correlation between radiographic and physiological findings in asbestosis T. Mattsson, P. L. Kalliomäki, O. Korhonen, V. Vaaranen Lung contamination among workers exposed to dust with an iron component T. L. Guidotti Arc welders pneumoconiosis: Studies with advanced techniques of scanning electron microscopy and microprobe analysis H. Shida, K. Chiyotani, Y. Saito Application of the four-fold magnified selective alveolobronchography to pneumoconiosis 641 653 661 691 693 705 719 733 747 SESSION IX IX/1 K. Robock, U. Teichert Techniques, strategies and results of dust measurements in the asbestos industries 755 IX/2 P. H. Cooper, J. E. Day, C. A. Kennedy, H. C. Lewinsohn Dust control in a conventional asbestos textile factory 775 IX/3 A.A.Cross Progress in the control of asbestos dust in the work place 793 1X74 A.Gibbs The environmetal data base for prevention studies in Quebec 807 IX/5 A.Schütz Protection against quartz and asbestos dust exposures at workplaces ..815 IX/6 B. Carton, E. Kauffer, J. C. Vigneron, M. Villa Comparaisons des différentes techniques de comptage des fibres d'amiante 823 IX/7 A. Degoumois Cas d'application de la convention de l'OIT (N° 139) sur le cancer professionnel, 1974, en relation avec le flocage à l'amiante des structures métalliques et des tuyauteries d'un immeuble en construction à Genève. . 833 SESSION X X/1 D.Ascarrunz Factores medio-ambientales y silicosis en Bolivia X/2 V. V. Tkatchev Two-stage gravimetric method of dust concentration measurement and its application in ore mines X/3 C.Amoudru Problèmes méthodologiques actuels de la lutte contre les pneumoconioses dans les charbonnages français X/4 N. Wiles, F. Fairclough The prevention and prevalence of pneumoconiosis in New South Wales coalmining X/5 V. S. Nikitin Modern methods of dust control in open-pit mines in the Soviet Union. 839 851 865 871 . 885 SESSION XI XI/1 A. Bulmer Developments in dust control and dust suppression in mining, tunnelling and quarrying, engineering control, organisational aspects, medical prevention XI/2 L. Le Bouffant, J. C. Martin, H. Daniel Effet des aerosols de sels d'aluminium pour la prévention et le traitement de la silicose XI/3 M. L. H. Flindt Prevention of illness due to allergenic dusts 897 911 929 **^«¿:f XI/4 W. T. Ulmer Coal workers'pneumoconiosis long-time treatment and its outcome XI/5 D. Else, N. Caro Problems associated with the use of half-mask respirators in dusty environments of developing countries . . . 939 949 Working Group No. 1 working Group No. 2 963 967 List of Participants 971 P R E F A C E Vth International Pneumoconiosis Conference Caracas, Venezuela, 29 October to 3 November 1978 The International Labour Office in co-operation with a number of national institutions and agencies has conducted up to now a series of International Pneumoconiosis Conferences. The first of these was presented in Johannesburg in 1930, the others in Geneva (1938), Sydney (1950) and Bucharest (1971). The fifth Conference on occupational lung diseases was organised in 1978 in Caracas, Venezuela. Since then the Vlth International Pneumoconiosis Conference was held in Bochum in 1983; the Vllth International Pneumoconiosis Conference is in preparation. The Vth International Pneumoconiosis Conference held in Caracas in 1978 was of high importance. Four hundred and sixty-three participants were assembled. Among them 160 scientists, practitioners, physicians, government officials, employers and workers representing 40 foreign countries. Seventytwo scientific papers were presented in twelve sessions. Three panel discussions dealt with the subjects: Occupational risk due to exposure to asbestos and methods of its prevention; Synergic effects of combined exposure to dust and other occupational hazards at the workplace; How to improve the conditions of man at .work. Two working groups were convened, dealing with the revision of the international radiographic classification of pneumoconioses, and with safe limits of exposure to mineral and vegetable dust in the working environment, respectively. Moreover, parallel to the sittings of the Conference, four postgraduate courses of 10 hours each were held on basic diagnosis of pneumoconioses, on cardiopulmonary physiopathology, on safety and health inspection and on dust monitoring.Two courses of 20 hours each were conducted on industrial toxicology and on organisation of occupational health services in enterprises. These courses were attended by 260 participants. Unfortunately, due to a number of obstacles, it was not possible to publish the proceedings of the Vth International Pneumoconiosis Conference immediately after this event. In doing so now, we will not only fill the gap in the series 9 2. of the published proceedings of all ILO International Pneumoconiosis Conferences, but in particular will pay tribute to the science and practice of occupational health. Important research results were reported which would not reach the scientific community without publication. Some of the observations and ideas expressed may be outdated, nevertheless they remain valuable as documentation of steps in the history of occupational medicine. The papers have been reprinted in the original form without editorial changes. Reports of the two working groups are included in the publication. The objective of publishing this material is to make it available to scientists and the occupational health practice through libraries of the ILO and scientific institutions. Moreover, copies can also be ordered directly from the publisher. We wish to express our thanks to the Organising Committee of the Vth International Pneumoconiosis Conference, and in particular to the President of the Confernece, Dr. Manuel Adrianza whose untiring enthusiasm resulted in a most successful meeting. Occupational lung diseases remain the major occupational health problem to workers. This publication will help to stimulate worldwide efforts for the prevention and the control of dust-related respiratory diseases. August 1985 International Labour Office 10 P R E F A C I O V Conferencia Internacional de Heumoconiosla Caracas, Venezuela; 29 octubre al 3 de noviembre de 1978 La Oficina Internacional del Trabajo en cooperación con varias Agencias e Instituciones nacionales ha dirigido hasta ahora las series relacionadas con las Conferencias Internacionales sobre neumoconiosis. La primera de ellas celebrada en Johannesburgo en 1930, las otras en Ginebra (1938), Sidney (I95O) y Bucarest (197D. La quinta Conferencia sobre enfermedades pulmonares del trabajo fué organizada en 1978 en Caracas, Venezuela. La sexta Conferencia Internacional de Neumoconiosis se realizó en Bochum en 1983. La séptima se encuentra en preparación. La quinta Conferencia Internacional de Neumoconiosis celebrada en Caracas en 1978, fué de gran importancia: 463 participantes se reunieron, entre ellos 16O científicos, practicantes, médicos, representantes oficiales, empleadores y trabajadores de Uo países. Setenta y dos trabajos científicos se presentaron en 12 sesiones. Tres paneles de discusión se condujeron sobre los temas: los riesgos del trabajo debidos a la exposición al asbesto y los métodos para su prevención'; efectos sinérgicos de la exposición combinada a polvos y a otros' riesgos en el sitio de trabajo; cómo incrementar las condiciones del hombre al trabajo. Dos grupos de trabajo fueron formados para intervenir sobre la revisión de la Clasificación Internacional de Radiografías de Neumoconiosis y con los limites de exposición seguros a polvos minerales y vegetales en el ambiente de trabajo respectivamente. Mas aún, paralelo a la realización de la Conferencia, cuatro cursos de postgrado de 10 horas fueron impartidos sobre las bases diagnósticas de la neumoconiosis, la fisiopatologia cardiopulmonar, la inspección de la seguridad e higiene y el monitoreo de los polvos. Dos cursos de 20 horas cada uno se llevaron a cabo sobre toxicología industrial y sobre la organización de los servicios de salud en las empresas, a estos cursos asistieron 260 participantes. 11 2. Desafortunadamente, por un gran nùmero de obstáculos no ha sido posible la publicación de los trabajos de la V Conferencia Internacional de Neumoconiosis inmediatamente después del evento. Por ahora, no quisiéramos dejar incompleta la publicación de los artículos de esta serie de las Conferencias Internacionales de la OIT sobre Neumoconiosis, en particular quisiéramos pagar un tributo a la ciencia y a la práctica de la salud en el trabajo. Fueron reportados resultados importantes de investigaciones que no quisiéramos dejarlos sin publicar para la Comunidad Científica. Algunas de las observaciones e ideas que se expresaron posiblemente no sean vigentes, sin embargo harían falta como una documentación valiosa sobre las etapas que ha tenido la historia de la Medicina del Trabajo. Los trabajos han sido reimpresos en su forma original, sin cambios editoriales. Los reportes de los dos grupos de trabajo han sido también incluidos en la publicación. El objetivo de publicar este material es ponerlo a disposición de los hombres de ciencia que practican la salud en el trabajo, a través de las librerías de la Organización Internacional del Trabajo y de las Instituciones Científicas. Copias aparte que se deseen, pueden ser ordenadas directamente al editor. Expresamos nuestro agradecimiento al Comité Organizador de la V Conferencia Internacional de Neumoconiosis, en particular a su Presidente Dr.Manuel Adrianza, quien por su inagotable entusiasmo hizo que los resultados de esta reunión fueran prósperos. Las enfermedades pulmonares del trabajo, persisten como uno de los mayores problemas de salud de los trabajadores. Esta publicación ayudará a estimular en todo el mundo, los esfuerzos para prevenir y controlar las enfermedades respiratorias ocasionadas por los polvos. Agosto de 1985 Oficina Internacional del Trabajo 12 I N D I C E S E S S I O N "I J.A.merchant. Coal Workors' Pneumoconiosis Surveillance in the United States JfS.fflcL intock. The Prevalence of Pneumoconiosis In British Coal Winers, 1959-1977 C.Dequeldre Cpldemiologle des Pneumoconioses dang les charbonnages de la campin belge. A.minette Peculiar aspects of the natural history of chronic bronchitis in coal miners. CI.Jacobson. Dust Exposure and Pneumoconiosis at 10 british coal mines. 13 COAL WORKERS' PNEUMOCONIOSIS SURVEILLANCE in the ' UNITED STATES J. A. Merchant, Division of Respiratory Disease Studies, Appalachian Laboratory for Occupational Safety and Health, National Institute for Occupational Safety and Health, USA The Coal Mine Health and Safety Act of 1969 was landmark legislation which mandated, among many health and safety provisions, a res. pirable coal mine dust standard of 2.0 mg/m , a vigorous mine inspection and enforcement program (Mine Enforcement and Safety Administration), coal mine safety and health research, and routine medical examinations of underground coal miners in the United States. Despite this legislative emphasis on mine safety, the latest available fatality rates per 1,000 full-time workers (1976) revealed a job-related fatality rate of 0.49 for the mining industry group as opposed to the agriculture, forestry, and fishing industry group which had the second high job-related fatality rate of 0.28 (Figure 1). In the area of dust control, great strides have been made since 1969. Table 1 reviews Mining Safety and Health Administra- tion (MSHA), formerly the Mine Enforcement and Safety Administration (MESA), data which compares operator and MSHA mean respirable dust levels from July-December of 1972 through January-June of 1978. Although operator-generated dust levels tended to be somewhat higher in earlier years, over the first half of 1978 there was good agreement on a mean dust level of 0.5 mg/m . Dust control has also been generally achieved in underground mines (Table 2) 15 where there has been steady Improvement since 1972 and good agreement between operator and MSHA samples with the overall mean dust level of 1.2 rag/m for the period January through June of 1978. The ability of the U.S. coal mining industry to maintain the re* latlvely good dust control mandated by the Act is attributable to major Improvements in mine ventilation, predominant use of room and pillar mining techniquesf and the lack of significant use of diesel powered equipment in underground coal mines. Although a mean respirable dust level 1.2 mg/m Is well under the standard of 2.0 mg/m , not all sections of all mines meet a 2.0 mg/m standard. This is particularly true for long-wall operations. In Table 3, data from a 1969 MSHA survey of 28 mines is compared to all MSHA data collected for the years 1973, 1976 and 1977. The improvement in dust control from 1968-69 is clear. This data, however, points out marginal dust control for jacksetters and longwall operations. An important provision of the Federal Coal Mine Health and Safety Act of 1969, and which was reiterated in the Federal Mine Safety and Health Act of 1977, was for medical examinations of underground coal miners. As reviewed in Table 4, the Act calls upon NIOSH to administer this health surveillance program, for coal mine operators to pay for these examinations, for the re- sults of these medical examinations to be submitted to the De- partment of Labor (MSHA), which In turn notifies the miner of any rights and benefits which may include transfer without loss of pay to a less dusty area of the mine (under 1 mg/m ) should the miner's chest radiograph show evidence of coal workers' pneumoconiosis. In order to administer this program, NIOSH through 16 its Appalachian Laboratory for Occupational Safety and Health (ALOSH) has certified a large number of coal mine operator examination plans and examination facilities throughout the coal fields of the United States (Table 5). It is the responsi- bility of the coal mine operator to arrange for periodic exami- nations (no less than every five years and more frequently for new miners) of his miners through development of a Mine Operator Plan, approved by ALOSH, for examinations at a conveniently located facility. In order to qualify, the facility must be able to pro- vide satisfactory radiographic equipment, technicians and physicians all meeting minimum qualifications set forth under regulations for administration of this program (42 Code of Federal Regulations, Part 37). The medical examination currently consists of a brief occupational history questionnaire and a posteroanterior chest radiograph. The radiograph is initially interpre- ted using the ILO U/C 1971 classification*' ' by a physician who may be either an "A" reader or "B" reader. "A" readers are those so designated because they have attended a training course on the radiographic interpretation of the pneumoconioses provided by the American College of Radiology under contract with NIOSH, or by correctly classifying six radiographs of pneumoconiosis of their own choosing. The film is then sent to ALOSH for processing and re-reading by a "B" reader, so designated because he or she has passed a proficiency examination on radiographic interpretation of the pneumoconioses developed by John Hopkins University. If the initial reader and "B" reader agree within a minor category (ILO U/C 1971 classification), the film is classified by the "B" read- 17 ing and the miner provided this information plus information on rights and benefits through the Department of Labor. Should the first two readings not agree, a further "B" reading is obtained. Ultimately, the film may be sent to a panel of readers for resolution of differences in interpretation. Results are now available for two rounds of this programs Round One from August 18, 1970 to July 27, 1973, and Round Two from July 27, 1973 to July 28, 1978. Table 6 summarizes the prevalence of coal workers' pneumoconiosis (CWP) by region. Although it has not been possible to determine the'exact proportion of underground miners participating in each round, it is thought to be close to sixty per cent for each round. Therefore, the increased number of miners examined in round two is largely a reflection of new miners coming into the industry since the beginning of Round Two. There is an apparent trend toward a lower prevalence of CWP in western states as compared to the Midwest and especially Appalachia in both rounds. There is also an apparent reduction in CWP prevalence (10% to 6%) between Round One and Round Two. However, when one examines the distribution of miners in each Round by years underground (Table 7), there has clearly been a major shift in the miner population and thus accumulated underground dust exposure between rounds. The avail- ability of federally funded compensation for lung impairment for coal miners, also a provision of the Federal Mine Health and Safety Act of 1969, may well be a contributing factor in explaining the lower number and proportion of men with greater than ten years underground. The explanation for the increase 18 tn new miners is largely attributable to the "energy crisis" of 1973 and the renewed emphasis on coal production In the United States. When CWP prevalence by duration of underground exposure specific rates are compared (Tables 8-10), there is no convincing trend toward less CWP from Round One to Round Two. Pneumoconiosis observed among those with less than one year underground exposure is thought to be largely attributable to previous exposure to pneumoconiosis producing dusts. CWP prevalence among those ex- posed underground from one to ten years is similar (Table 9), but somewhat Increased in Round Two among those exposed for more than ten years (Table 10). Examination of Table 10 reveals that near- ly all of the increase in prevalence occurs In radiographic Category 1, while the prevalence of progressive massive fibrosis (PMF) is reduced by half. It is thought that some of the increase In CWP prevalence in Round Two is attributable to a change In radiographic reading schemes (UlCC/Clncinnati 1968 In Round One and ILO U/C 1971 In Round Two). tations on the Table 11 examines the interpre- 26,374 miners common to both rounds of examinations. The expected variation in interpretation as well as evidence of a higher prevalence of Category 1 CWP in Round Two is observed tn these figures. Further examination of the prevalence of CWP by years underground in Round Two reveals a strong association between years underground and prevalence of CWP (Table 12). This data also reveals that nearly all Category 3 CWP and PMF occurs among miners exposed underground for twenty years or longer, a reflection of conditions preceding improved dust control. 19 Another element of health surveillance of coal miners is periodic review of their mortality experience. Recently a large cohort (n= 22,998) of coal miners was studied by Rockette et al (3) v under contract with NIOSH . Major causes of death are review- ed in Table 13. Although all causes of death did not differ from the white male U.S. mortality experience, it is higher than rates quoted for healthy working populations. A number of respiratory causes of death were found to be significantly increased - influenza, emphysema, asthma, and tuberculosis. Similarly, accidents, ill- defined causes and all other causes were significantly increased while a number of chronic disease categories revealed apparent decreases-major cardiovascular diseases, diabetes mellitus, peptic ulcer, and cirrhosis of the liver. Although the standard mortality ratio (SMR) for all neoplasms was not significantly different from the standard population (Table 13), there were some individual cause specific neoplasms which did increase (Table 14), most notably stomach cancer and a modest but significant increase in neoplasms of respiratory organs and lungs. Although an increase in SMR's for stomach cancer among underground coal miners has been found in several previously published reports, ' ' ' pre- vious studies in regard to lung cancer are conflicting^ ' '. The following conclusions are drawn from the data presented: 1. By the most recent available figures, mining remains the most hazardous major industry in regard to job-related fatalities in the United States. 2. Marked improvement in the control of respirable coal mine dust has been achieved by the coal mining industry since 2o passage of the Federal Coal Mine Health and Safety Act of 1969. Apparent declines In the prevalence of CWP are accounted for by shifts in the mining work force toward miners with fewer years underground. No trend toward less CWP since dust control is yet apparent after two rounds of examinations. Recent mortality figures show continued excess mortality non-malignant respiratory diseases and accidents, but also excesses in lung cancer and particularly stomach cancer which deserve further inquiry. Job—Relatad Fatalities Due To Injurie» and Illnesses By Industry Group* 0.08 Private Sector H H | 0.49 Agriculture, Forestry, Fishing 0.28 0.25 Transportation, Public Utilities Manufacturing 0.19 pjffjj 0.06 0.05 Services Wholesale and Retail Trade 1 Finance, Insurance, Real [state !» 0.04 Fatoßty rates pe r 1.000 full—time works rs for 1976, 01 Bur•au ot labor Statistics. 21 TABLE 1 COMPARISON - OPERATOR AND MSHA SAMPLES SURFACE (MG/M*) OPERATOR MUÍA SÁMELES. AYEBAfiE. SÁMELES. AYEBAGE. 1972 62,543 1973 75,527 1974 75,571 1975 95,679 1976 106,527 1977 93,564 0.7 0.5 0.5 0.5 0.7 0.4 12,749 0.5 1.2 1.1 0.8 0.7 0.5 48,018 0.5 5,214 0.5 JUL.-DEC. 3,927 2,265 2,258 2,946 5,701 JAN.-JUNE 1978 SOURCE: MINING SAFETY S HEALTH ADMINISTRATION, 1978 22 TABLE 2 COMPARISON - OPERATOR AND MSHA SAMPLES UNDERGROUND (MG/M*) OPERATOR SÁMELES;A^EBASE. MSHA Í&EBASE. SAMELEI JULY-DEC 25,556 301,488 1.6 1.2 1.2 1.2 1.3 1.0 11,357 1.5 1.9 1.8 1.5 1.2 1.1 125,701 1.2 4,924 1.2 1972 187,618 1973 346,538 1971 317,872 1975 384,905 1976 395,432 1977 9,347 10,457 9,939 14,245 JAN-JUNE 1978 SOURCE: MINING SAFETY & HEALTH ADMINISTRATION, 1978 23 TABLE 3 HIGH Ri! 1968-1969 1973 1976 1977 JACKSETTER H.2 LONGWALL 2.6 2.1 2.1 1.8 2.7 1.9 1.8 1.3 1.1 1.2 1.2 1.9 2.2 1.3 1.2 1.1 1.3 CONTINUOUS MINER OPERATOR ROOFBOLTER CUTTER OPERATOR LOADER OPERATOR SOURCE: 6.5 3.9 5.9 6,0 MINING SAFETY & HEALTH ADMINISTRATION, 24 1978 TABLE 1 PROVISIONS OF THE FEDERAL MINE SAFETY AND HEALTH ACT OF 1977 (1) NIOSH ADMINISTER A COAL MINER HEALTH SURVEILLANCE PROGRAM (2) COAL OPERATIONS PAY FOR (3) RESULTS OF EXAMS SUBMITTED TO DEPARTMENT OF LABOR (4) DEPARTMENT OF LABOR NOTIFY MINER OF RIGHTS AND BENEFITS (5) TRANSFER RIGHTS AND RATE RETENTION EXAMINATIONS 25 en oo i—) i>>. CM CO tr\ oo LT> co o; O è LU £: LO oo t>N. >- cr en CM i x O CO on ca <c ÇQ — a> LU i— CU •-. LU <-> ~ CO a. o ce i—i CD Ou 3 CO CO sz in en O •—• en i tv. fv O OO OO tv. tv. I>0 LO l>r> 3 Si z: > O DC Q_ X 111 •—• Qu <_> LL<c CS <c tv en s en c/> UJ (/> CE UJ U} ce LU <_> ce Q LU > O ce LU p § § _l ce CE: % <c % ça ^ M t z•-•o< LL. UJ o PLAN o. AL M — K •—• —I LU ce o 1< a. 26 TABLE 6 PREVALENCE OF CWP B Y REGION REGION N ROUND ONE '% MIDWEST 7,539 WEST 1,827 14 8 5 71,008 10 APPALACHIA TOTAL 61,661 ROUND TWO N % 93,723 6 14,824 5 5,619 2 111,166 TABLE 7 DISTRIBUTION OF MINERS BY YEARS MINING YEARS MINING ROUND 1 N ROUND 2 % N % 15,853 22.2 52,809 46.3 1 - 10 21,637 30.3 39,871 34.9 >10 34,023 47.5 21,486 18.8 <1 TOTALS 71,513 114,166 27 TABLE 8 CWP BY ROUND <1 YEAR MINING EXPOSURE RADIOGRAPHIC CATEGORY ROUND ONE ROUND TWO % N N X 99.9 0.1. 0 1 2 3 PMF 15,755 99.3 52,772 79 15 0 4 0.5 0.1 31 2 0 1 TOTALS 15,853 0.6 - 52,809 28 - 0.1 TABLE 9 CWP BY ROUND 1-10 YEARS MINING EXPOSURE RADIOGRAPHIC CATEGORY ROUND ROUND ONE TWO 0 N 21,255 Z 98.2 N 39,171 Z_ 98.2 1 340 1.6 638 1.6 2 35 0.2 37 0.1 3 2 - 2 5 - 23 0.1 39,871 1.8 PMF TOTALS 21,637 1.8 29 TABLE 10 CWP BY ROUND >10 YEARS MINING EXPOSURE RADIOGRAPHIC CATEGORY N 26,574 4,716 1,857 TOTALS ROUND ROUND ONE TWO Z % N 78.1 13.9 143 733 5.5 0.4 2.2 34,023 21.9 3o 15,626 4,473 1,043 72.7 20.8 114 230 4.9 0.5 1.1 21,486 27.3 CSI _J 1—1 en «a: h- es 1—1 O LO o h— csi^ 1—1 CSI 1—1 LO 1 1—1 LO LO OO 1—1 CS i j CS 00 CSI CSI t-H 1— LO ro in ro i-i CT IO |x» CSI CSI e: en LO CSI i—l •=r UD 00 •-I •—i LO 00 LO i-i •-I i-i O LO r^ en LO i-H en CSI CS >et: X CSI er: ce o 2i ro o o i-H CD LU I— tv» ^ OO I—I CSI CSI cr LO CSI LO 1—1 El Q_ oc co os o 1-1 ^ « «a: 1-1 ro CSI U_ CO i—i <x 1— oc O ro o en •=r CSI co f— CS 6-Í O 1—1 w s i-H 31 CSI NI en i n II il CSI CSI _l _i < Z < z ea o N ^ LO < ça fr« •ÏT O LO LO CSI O (9 i—1 *-N LO en o LO < « LL. ILI X E > o <« £ _i LU CQ o TABLE 12 ROUND TWO RADIOGRAPHIC CATEGORY ÜfífÍG O N 1 m % N 2 3 m PMF % N % N % N - 19 % 3-9 90,520 99.3 585 0.6 35 - - 10-19 7,316 87.1 973 11.6 83 1.0 4 0.1 22 0.3 20-29 5,192 72.2 1635 21.5 387 5.1 26 0.3 69 0.9 30-39 3,336 62.0 1167 27.3 428 8.0 61 1.2 88 1.6 905 56.0 485 30.2 149 9.2 20 1.2 56 3.5 107,569 94.2 5145 4.5 1082 0.9 116 0.1 254 0.2 40+ TOTAL 32 TABLE 13 STANDARD MORTALITY RATIOS FOR COAL MINERS FOR SELECTED CAUSES OF DEATH (N - 22,998) SJÜR CAUSE OF DEATH 101.6 ALL CAUSES 97.7 ALL MALIGNANT NEOPLASMS 95.2* 189.6* MAJOR CARDIOVASCULAR DISEASES INFLUENZA ASTHMA M3.7* 171.9* TUBERCULOSIS M5.5* EMPHYSEMA DIABETES MELLITUS 58.1* PEPTIC ULCER 71.6* CIRRHOSIS OF LIVER 61.0* ACCIDENTS 1M.2* ILL-DEFINED CAUSES 187.9* ALL OTHER CAUSES 136.0* *P¿.05 SOURCE: ROCKETTE (3) 33 TABLE.14 STANDARDIZED MORTALITY RATIOS FOR COAL MINERS WITH SELECTED NEOPLASMS CAUSE OF DEATH SUR BUCCAL CAVITY AND PHARYNX 83.6 DIGESTIVE ORGANS AND PERITONEUM 97.8 138.2* STOMACH COLON 69.9* OTHER DIGESTIVE CANCERS 96.4* 112.4* RESPIRATORY ORGANS 113.7* LUNG OTHER RESPIRATORY CANCERS 93.7 82.6* GENITAL ORGANS *pé.05 SOURCE: ROCKETTE (3) 34 REFERENCES 1. ILO U/C International Classification of Radiographs of Pneumoconiosis. Occup. Saf. Health Serv.(rev. 2 2 ) , International Labour Office, Geneva, 1972. 2. Morgan, R.H.: Decision processes and observer error in the diagnosis of pneumoconiosis by chest roentgenography. Am. J. Roent., Rad. Ther. & Nuc. Med. 3. Rockette, H. : Mortality among coal miners covered by the UMWA Health and Retirement Funds. DHEW (NIOSH) Publication No. 77-155, 1977. 4. Stocks, P.: On the death rates from cancer of the stomach and respiratory diseases in 1949-53 among coal miners and other male residents in counties of England and Wales, 1962, Brit. J. Cancer, 16, 592-598. 5. Enterline, P.E.: Mortality rates among coal miners, May, 1964, Amer. J. Pub. Health, _54, 758768. 6. Liddell, F.D.K.: Mortality of British Coal Miners in 1961, 1973, Brit. J. Ind. Med., .30, 1-14. 7. Costello, et al: Mortality from Lung Cancer in U. S. Coal Miners, Mar., 1974, Amer. J. Pub. Health, £ 4 , 222-4. 35 vip.ilancia de la neumoconiosis do los mineros del carbón en Estados Unidos Informe introductorio por A. Merchant, Estados Unidos La Ley de 1969 sobre seguridad e higiene en las minas de carbón establecía, entre otras muchas disposiciones en materia de seguridad e higiene, que en Estados Unidos los mineros del carbón fueran sometidos a exámenes médicos. Esta ley fijaba asimismo el nivel de las concentraciones respirables de polvillo o de carbón en 2 mg/m . Desde la entrada en vigor de esta legislación el Instituto Nacional de Seguridad e Higiene en el Trabajo, a través de su Laboratorio de los Apalaches, ha llevado a término un programa de exámenes y de vigilancia radiográfica para los mineros del carbón. La organización del programa de exámenes y los métodos y procedimientos para interpretar las radiografías serán objeto de debate. Actualmente se han concluido dos series completas de exámenes, con un total de más de 157000. Los resultados de estas dos series se examinarán junto con datos sobre concentraciones de polvo de carbón reunidos y facilitados por la Administración de la Seguridad e Higiene en las Minas del Ministerio de Trabajo de Estados Unidos. Las repercusiones de estos resultados en lo que atañe al control y prevención de la neumoconiosis de los mineros del carbón en Estados Unidos serán objeto de debate. 36 il» THE PREVALENCE OF PNEUMOCONIOSIS IN BRITISH COAL MINERS, 1959 - 1977 J. S. McLintock National Coal Board, United Kingdom Introduction There are a number of geographically discrete coal-fields in Great Britain (Fig.l) with distinctly different types of coal and, it would appear, different risks of pneumoconiosis. When the British coal-mining industry was nationalised in 1947, there were approximately 750,000 miners. It was recognised that there was a major pneumoconiosis problem in the South Wales coal-field but prevalence elsewhere was virtually unknown. The few years after 1947 were devoted to the reconstruction of the industry. were In the field of pneumoconiosis, dust standards introduced! dust control began, research to establish appro- priate dust standards was planned and investigations to measure the pneumoconiosis problem in the various coal-fields were started. Because of the geographical spread of collieries which on average employed about 1,000 miners - some coal-fields extended over 150 to 200 kilometres - it was desirable to base any periodic chest X-ray examination on mobile X-ray units. Investigations, comparing 70 mm miniature X-ray films with full-size, had shown the former to be inadequate for the accurate diagnosis of pneumoconiosis. At this time, some 25 years ago, there was very limited experience of the operation of mobile X-ray units using large film techniques. Planning therefore occupied much of the 1950s, but by the end of that decade a fleet of mobile X-ray units had been built, staff recruited and trained and record systems devised. 37 THE COALFIELDS OF GREAT BRITAIN LOCATION OF THE MAIN CLASSES OF COAL KM m nu 3« ftiMMM to Ww Nwtontf Ca* tOMl Hotel H K.SWI —Mar Iff* By 1959 a scheme offering a full-size chest X-ray to all miners on a regular basis was fully operational. Mobile units visited each colliery in turn and examination was on a voluntary and confidential basis. Because dust control measures had considerably reduced the airborne dust levels in British mines, the radiographic appearances of pneumoconiosis were slow to change and it was considered appropriate to set the interval between colliery visits at 5 years. (By this time pulmonary tuberculosis was being brought under control and the need for frequent X-ray surveys of the population was beginning to disappear). general The objectives of this Periodic Chest X-ray Scheme (P.X.R.) were«(a) To offer each mine worker the safeguard of a regular chest Xray, and (b) To use the epidemiological data collected to assess the efficacy of the dust control programme. PREVALENCE - 1959 - 1963 This first round of surveys demonstrated the prevalence of pneumoconiosis in the various coal-fields. 39 (Fig.2.) fofi-2. Prevalence of pneumoconiosis in British coal—fields, 1959 - 1963. Key .Coal-field No. of men .X-rayed SCOTTISH 53,849 NORTHERN (N&C) 27,458 URHAM YORKSHIRE D Prevalence Cats. 2 & 3 ^ w m?% 101,001 32,587 EAST MIDLANDS 80,087 WEST MIDLANDS 34,551 SOUTH WESTERN 6o,286 SOOTH EASTERN 3,875 GREAT BRITAIN 462,999 P.M.P. ^ 69,305 NORTH WESTERN Cat. 1 mtm m ^ mmi ^ 0* ^ T '% 'IO* T \% Per cent of men X-rayed »0 20fr These coal-fields were using the same techniques and equipment; the men were virtually all British (a few Poles and even fewer Hungarians had entered the industry, but the labour force was almost 100% British) with much the same age structure in the various mining areas. Yet the difference in prevalence is marked with South Wales highest and Scotland and Northumberland lowest. The coals of South Wales are in general anthracite and high quality bituminous, while in Scotland and Northumberland they are of distinctly lower quality. It is therefore not to be expected that every country will experience the same pneumoconiosis risk. Much will depend on the type of coal mined in addition to dust control measures adopted. PREVALENCE 1959 - 1977 Between 1959 and 1977 four rounds of surveys have been completed and the overall prevalence on each occasion is shown in Fig. 3. 41 Fig.3. Prevalence of pneumoconiosis in British miners 1959-1977« 1$ ^ =. P.M.P. ////X/ = Cats. 2 & 3. ¥&M = Cat. 1. 1964-68 1969-73 10$ TOTAL PREVALENCE 1974-77 ss/ss s % ¿ 536 o?S 42 Not only has the overall prevalence improved but the prevalence in each age group shows a very satisfactory trend. Figure 4, which illustrates this, is based on data from 219 collieries which were surveyed in each of the four rounds. Pig. 4. Prevalence of pneumoconiosis by age-group at 319 collieries surveyed in 305S _ 1959-63, 1964-68, 1969-73 and in 1974-77. 1959-63 1964-68 1969-73 203Í - 1974-77 IO56 _ 15-24 25-34 43 35-44 45-54 55-64 PROGRESSION 1964 - 77 In Britain, miners with pneumoconiosis are given a state pension but are permitted to remain in the coal-mining industry if they so wish. Most choose so to do; naturally they are offer- ed employment in particularly low dust conditions. Nevertheless, it is possible that the changes in prevalence shown above could be due to the selective departure of men with pneumoconiosis. Various checks have failed to demonstrate such an effect, but it was considered desirable to develop a further indicator of change. This was done for each colliery by taking two successive X-rays of all men working on the coal-face at the time of the first of the two surveys and who remained at that mine throughout the interval between the surveys. These radiographs are categorised in the elaboration of the ILO classification by at least two doctors specialising in this work. (The elaboration was originally developed within the National Coal Board specifically for this purpose.) The results are expressed as the number of additional steps recorded in the elaborated scale for 100 men in the sample. Obviously, as only one chest radiograph was available in the first round of surveys, it was not until the second round of surveys started in 1964 that the progression index for each colliery could be determined. Figure 5 shows the progression indices year by year from 1964 to 1977. 44 ^ ^ ^ ^ ^ I-1 ^ \ O \ 0 B! í o H X\\\\\\\\\\\\\\\N , \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ' ^ x\\\\\\\\\^ X \ \ \ \ \ \ \^ \\W\M "q xw^ ^5 8 CHANGES IN PREVALENCE AND PROGRESSION During the late 1950s and 1960s, oil became a major fuel In Western Europe. Çoal mining industries began to contract and in Britain the number of miners decreased from some 750,000 to approximately 250,000. However this reduction did not occur because of the departure of older men especially those with pneumoconiosis! rather it was the younger men who left the industry. Thus the change in manpower was not calculated to have any significant effect on prevalence. However especially in the 1950s and 1960s major technical changes were taking place. In the first decade the long-wall coal face was established as the principal method of coal-getting in Britain and at the same time great improvements were made in ventilation. During the 1960s, mechanised methods of extracting, loading and transporting coal were developed intensively. These new techniques in mechanisation presented new problems in dust control and it took some time for our engineers to find solutions. Thus, between 1959 and 1963 the prevalence of pneumoconiosis in the various coal-fields was established. When the results from the second round of surveys became available between 1964 and 1968, a clear improvement in prevalence and progression could be seen, but in the third round from 1969 to 1973 this improvement slowed down and at one stage appeared to be halted. However in 1970 new gravimetric dust standards were introduced and a renewed drive on dust control began. The results began to appear in improved prevalence and progression data in 1973, and the results from the 1874-77 round of surveys are 46 very encouraging in all coal-fields. CONSISTENCY OF DATA The diagnosis and categorisation of pneumoconiosis on a chest radiograph is to some extent a subjective judgement. All subject- ive judgements are liable to vary from person to person, and from time to time in the same person. This is certainly true in the field of pneumoconiosis and in endeavouring to minimise this effect within the Periodic Chest X-ray Scheme, particular attention is paid toi (a) the consistency of X-ray film q u a l i t y . (b) the consistency of radiological diagnosis. We are fortunate in that the mobile X-ray units which provide this service operate from only six centralised bases in the various coal-fields. The 15 radiographers who take the chest radiographs and the 7 radiologists who interpret them, are engaged full-time in this work and can therefore concentrate particularly on consistency of film quality and of diagnosis. A code of practice is in force involving frequent checks on generator output, film speed, cassettes and film screens, processing chemicals and temperatures and archival permanence of the processed film. But more importantly a large sample (of the order of 30%) of radiographs from each X-ray base are examined for quality by at least two radiologists from another base who of course report their comments back. In addition regular meetings are held of radiographers and of radiologists to ensure that there is general agreement on film quality and that all possible steps are taken to maintain a consistently high level. Similarly the 7 radiologists ft7 meet several times per year and in discussion concert their diagnostic standards. carried out regularly. In addition several formal tests are In one, each radiologist is required to interpret 350 radiographs, 100 of which had been included in the previous year's test and 250 of which are included for the first time. Figure 6 demonstrates the consistency of performance. CONCLUSION Dust control is rapidly reducing the pneumoconiosis problem in British coal-mines, but to ensure that the results of radiographic surveys can be compared over the years.it is essential that consistency of film quality and of diagnostic standards be maintained, and formal systems to ensure such consistency have been introduced. *8 ? s s? sr ? s ? Ö o td ¡» P co s o i s »9 E/2 PNEUMOCONIOSIS IN BRITISH COALHINERS, 1959-77 T.S. MoLintock (united Kingdom) In 1959 a Periodic X-ray écheme was introduced for B r i t i s h miners. Since then motile X-ray u n i t s , using large film teohniquea t have v i s i t e d every c o l l i e r y on a regular basis» Almost 92 per cent of miners, both surface and underground, have come forward for examination on a voluntary b a s i s . In the f i r s t s e r i e s of surveys over 460,000 chest X-rays were taken; because of the contraction of the coalmining industry in B r i t a i n during the 1960s and e a r l y 1970s, the number had f a l l e n t o 200,000 i n the most recent round. This paper desoribes the prevalence of pneumoconiosis i n the various c o a l f i e l d s of B r i t a i n and the changes «hieb have taken place over the years as dust control becomes more e f f e c t i v e . To ensure the comparability of the survey r e s u l t s over the y e a r s , emphasis has been l a i d on (a) the maintenance of high q u a l i t y of X-ray films and (b) the consistency of interpretation- by the r a d i o l o g i s t s concerned. Both the systems developed are s e t out. 50 1/3 EPIDEMIOLOGIE DES PNEUMOCONIOSES DANS LES CHARBONNAGES DE LA CAMPINE BELGE G. Degueldre I 'ìnsiti tut d ' H v o i p n o rios f i n p s , M a s s a i t , Pe)ni nue. INTRODUCTION Le Bassin de Campine, situé dans le Nord de la Belgique, exploite sous 500-600 m de morts terrains aquifères, un gisement de charbon industriel (essentiellement charbon à coke) comprenant surtout de6 couches du Westphalien A supérieur et du Westphalien B inférieur, dont l'ouverture moyenne rarement l,50n. La production du Bassin est de l'ordre de 7 millions de tonnes nettes par an, réalisée dans des tailles chassantes en piateures d'une longueur de 200 m environ. Malgré leur faible puissance et leur profondeur (atteignant parfois 1000 m), certains chantiers complètement mécanisés produisent de 1500 à 2000 tonnes nettes par jour, le rapport net/ brut ou propreté gravimêtrique moyenne des veines étant de 75 %. Le débit d'air moyen par taille est généralement compris entre ROO et 900 vr d'air par minute. A. METHODES DE PRELEVEMENT ET D'ANALYSE DES POUSSIERES 1. La réglementation minière belge, toujours en vigueur, a été imposée en 1965; elle a introduit le prélèvement pondéral c'est-à-dire que les résultats de la mesure sont ex» primés en mg de poussières par nr d'air (mg/cr). 51 Etant donné le fait qu'à cette époque, on ne trouvait pas sur le marché des appareils sélectifs fiables, autonomes et d'emploi commode, les autorités minières ont adopté le principe du prélèvement gravimêtrique total ou "gravimétrie globale", la prise d'échantillon consistant à capter toutes les particules en suspension dans l'air, (prélèvement quasi isocinêtique). Cette façon de procéder, apparemment simpliste, a eu des effets bénéfiques certains, car tout chantier mis en exploitation sans prévention était irrémédiablement catalogué comme dangereux. 2. Les chantiers d'exploitation et ateliers souterrains des mines de bouille sont classés en fonction de la concentration en poussières de leur atmosphère (mg/nr) et en fonction également de la teneur en cendres de ces poussières ( % en poids). Cet aspect qualitatif de la poussière (c.à.d. teneur en cendres ou en stériles) se justifie pour des mesures de routine. Dans un gisement donné, il existe en effet une relation statistique simple qui permet de connaître, en moyenne, la teneur en silice libre ou quartz, à partir de la teneur en cendres, pour autant que cette dernière ait été déterminée suivant un mode d'analyse bien défini. Sans entrer dans les détails des modes opératoires prescrits pour l'emplacement, la durée, la fréquence des prélèvements, l'examen et l'analyse des poussières, le classement des chantiers ou des ateliers s'opère en se référant à certaines limites (classes I, II, III, etc,). Les travaux ne peuvent d'ailleurs actuellement 52 Otre poursuivis normalement que dans les chantiers ou ateliers classés I ou II, A titre d'information, sont classas I les chantiers dans lesquels les concentrations en poussières globales de toutes granulomêtries sont inférieures à 25 mg/ra* lorsque la teneur en cendres de toutes les particules en suspension dans l'air atteint une valeur de 30 à 35 %• 3Il va sans dire que depuis l'introduction de cette législation, d'autres techniques de prélèvement et d'examen ont été et sont utilisées dans les mines belges, pour mesurer notamment les poussières "dites respirables", l'échantillonnage se faisant en l'occurrence au moyen d'appareils sélectifs munis d'un êlutriateur ou d'un prôséparateur (appareils CPM-TBF-MREMPG). Une comparaison établie par l'Institut d'Hygiène des Mines dans les chantiers d'abattage campinole, montre que pour des particules charbonneuses & - 30 % de cendres, une concentration gravimêtrique globale de poussières respirables captées au CPM ou TBF et à 5 mg/m* de poussières reaplrablBB captées au MRE. (Cette comparaison ne vaut que dans la mesure ou elle tient compte de la granulometrie moyenne des particules qu'on obtient dans l'état actuel de la prévention des poussières pendant l'abattage). PREVENTION TECHNIQUE DES POUSSIERES - RESULTATS 1. L'importance de la lutte contre les poussières apparaît immédiatement lorsqu'on se rend compte que les concentrations mesurées dans les chantiers è hautes performances, mais sans prévention, peuvent dépasser de plus de 10 fois les valeurslimites proposées. 53 Les procédés visant à éliminer la poussière(qu'ils soient appliqués directement aux points de formation ou utilisés pour lutter contre les poussières sêdimentêes ou entraînées par le courant d'air) permettent heureusement, grâce à une combination judicieuse, d'atteindre des taux d'élimination de 90 % et plus, par rapport a ce qu'on mesurerait sans lutter contre les poussières. 2. Les moyens mis en oeuvre dans les charbonnages belges sont décrits régulièrement (°); on peut ainsi suivre et comparer d'année en année, l'évolution de la situation à cet égard. En ce qui concerne les chantiers d'abattage, les procédés classiques repris dans ces statistiques sont: l'injection ou infusion d'eau en (° ° ) , l'arrosage des fronts, le tion de piqueurs à pulvérisation de taille,... (éventuellement machines pulvérisateurs). vaine sous toutes ses formes havage humide, l'utilisad'eau dans les extrémités de creusement pourvues de ( °) Annales des Mines de Belgique - Revue de l'Institut d'hygiène des Mines. (°°) Une variante de l'infusion d'eau en veine, dénommée "prétôlê-inject^on" a été développée en Campine depuis 1963. Elle consiste a imprégner d'eau un panneau avant sa mise en exploitation en opérant à distance par sondages profonds creusés à partir de stations extérieures au panneau considéré. Elle est de ce fait complètement indépendante des cycles d'abattage; elle est susceptible par ailleurs de modifier dans un sens favorable la dêsorption du méthane au moment où se produit l'abattage. 54 En plus de la pulvérisation d'eau appliquée systématiquement sur les engins d'abattage et les transporteurs en taille, plus de 80 % de la production sont actuellement traités par ces procédés classiques de prévention (combinés ou non). 3. Les valeurs médianes des concentrations gravimétriques en poussières mesurées dans toutes les tailles en début ou en fin d'année, sont également communiquées régulièrement dans les revues précitées. Des études statistiques faites sur près de 1.500 prélèvements (effectués en 1976-77 on Campine) montrent que les valeurs médianes obtenues conduisent à des valeurs moyennes de l'empoussiêrage de l'air qui ne diffèrent pas significativement des moyennes arithmétriques annuelles ni même des valeurs moyennes pondérées de l'empouesiérags dans toutes les tailles. C'est ainsi que les concentrations globales médianes 12,5 et 12,0 mg/m , trouvées fin 1976 et fin 1977, correspondent è des valeurs moyennes de 16,0 et l/f,6 mg/m3, alors que les moyennes arithmétiques annuelles sont: 17,5 et 16,7 mg/m3, les empoussiérages moyens pondérés s'élevant à 16,74 et 16,^9 mg/m3, C'est pourquoi nous considérons que la concentration médiane (en fin d'année par exemple) est un bon indicateur de l'empoussiérage des chantiers. Notons que compte tenu de la granulometrie et de la nature des poussières, les empoussiérages moyens pondérés exprimés ciavant en gravimetria globale, correspondent à: ^ 3 , 5 mg/m3 et ^4,5 mg/m 3 de poussières "respirables CPM ou TBP' de poussières "respirable MRE". 55 k. L'évolution des concentrations (globales) médianes constatée en Campine depuis la mise en application de l'actuelle législation, est caractérisée par les valeurs suivantes: 33mg/n3 en 1965 15,5 mg/m 3 en 1975 21 mg/m 3 en 1970 12,2 mg/m 3 en 1977 (fin.] ) alors que la meilleure estimation donne pour I960 un empoussiêrage global médian de l'ordre de Zf5 mg/nr. A la fin de 1977, on trouve moins de ZZ,5mg/m3 de poussières dans R5 % des postee d'abattage, la moyenne pondérée (qui tient compte de la durée de vie des chantiers) s'êtablissant à 16,5 mg/nr de poussières de toutes granulometries. (c.a.d. <.3?5 mg/m3 de poussières respirables CPM). C-. RESULTATS MEDICAUX DE LA PREVENTION ET PERSPECTIVES 1. L'incontestable amélioriation des conditions de travail qui s'est produite en Campine depuis plus de 15 ans, grâce à la prévention technique, se traduit par une nette diminution des prevalences et incidences pneumoconiotiques. En particulier, les prévalences des pneumoconioses de ty<nes M2.(2/29)et 112 .... exprimée en % de l'effectif inscrit-fond dans chacune des classes d'ancienneté montrent que par rapport à la situation des années 1959/60, le risque de présenter actuellement une image radiologique HZ, M2 +• ... est considérablement réduit. En 1976, par rapport à la situation des années 1959/60,le ris-r que était 18 fois moindre pour ceux qui avaient 10 ans de fond 10 fois moindre pour ceux qui avaient 15 ans de fond 6,if fois moindre pour ceux qui avaient 20 ans de fond et 4,5 fois moindre pour ceux qui avaient 25 ans de fond.(fin.?> 56 En d'autre termes, ouvriers ayant 25 ans de siêrages élevés en début radiologique invalidante 1959/60. en 1976, on constatait que 9»5 % des fond (et ayant donc connu des empousde carrière) présentaient une image de type M2, M2+ ..., au lieu de 1,3 % en En 1959/60, environ 33% des ouvriers ayant 20 ans de fond présentaient aussi la même image radiologique. Depuis 197^, moins de P, % des ouvriers de môme ancienneté (5 % en 1976) ont la môme image radiologique, le taux d'incidence des pneumoconioses de type M2 et M2 • ...étant inférieur â 0,50 % pour les ouvriers mineurs ayant.de 20 à 25 ans de fond en Campine (en 1976). 2. L'ETUDE DES COURBES EPIDEMIOLOOJQUES PRESENTE UN AUTRE INTERET PLUS IMPORTANT ENCORE POUR ORIENTER LA LUTTE CONTRE LES POUSSIERES. En effet, si on admet que la probabilité d'apparition d'une pneumoconiose est une fonction cumulative d'une certaine fonction de l'empoussiêrage, il est possible de trouver une relation qui lie le nombre de sujets restés sains (après X années d'exercice de la profession) au nombre de sujets inscrits l'année zéro de référence. On peut en déduire une formule (dite formule de prévalence) dans laquelle intervient l'empoussiêrage "historique" c'est-à-dire l'empoussiêrage dans lequel les ouvriers sains l'année zéro de référence, ont eu à travailler pendant x années. Moyennant certaines hypothèses qui sont acceptables si la décroissance de l'empoussiêrage est linéaire (ce qui est le cas), et à condition d'admettre que les empoussiêrages médians mesurés pendant l'abattage donnent une "image valable" de l'empoussiêrage de la mine, on peut calculer l'empoussiêrage qu'il aurait fallu, en moyenne, ne pas dépasser pendant x années soit inférieure à une valeur donnée (°) (°) Ganier, M. Méthode pour la détermination d'un seuil d'empoussiêrage - R.I.M.- Mine, décembre. 57 Il est ainsi possible de fixer "une limite d'exposition aux poussières" qui n'est toutefois valable en toute rigueur que dans un gissement similaire. 3- Compte tenu des empoussiêrages obtenus en Campine et en se basant sur les courbes êpidêmiologiques tracées à partir des résultats de tous les examens médicaux effectués depuis 1959/1960, on en arrive à la conclusion quii aurait fallu ne pas dépasser en moyenne la médiane 13,75 mg/m^ pendant 30 ans (avant 1974) pour que le risque de présenter une image radiologique de type M2, M2 *•... ne dépasse pas 5 % après 30 ans de fond. On trouve par ailleurs que les empoussiêrages médians atteints en Campine en 1976-77 ne devraient pas provoquer, en moyenne, plus de 2,5 % d'images radiologlque M2 et M2 •• ... après 25 ans de fond (au lieu des 43 % de 1959/60 et des 9,5 % constatés encore en 1976). Ces empoussiêrages gravimêtriques globaux, traduits en "poussières respirables CPM" correspondent à une concentration moyenne de l'ordre de 3,4 mg/nr lorsque 5 prélèvements sur 6 donnent une valeur inférieure à 4,4 mg/nr.(dans les conditions propres au gisement campinois). Une telle "limite d'exposition aux poussières" pour 25 années de service entraînerait un risque pneumoconiotique 17 à 18 fois moindre que celui enregistré en 1959/60. On est même presque en droit d'affirmer que le risque de contracter une pneumoconiose de type 112, M2 + ... sera nul dans 20 à 25 ans pour ceux qui, indemnes au départ, ont commencé leur métier de mineur en 1976. 58 CONCLUSION L'étude des courbes épidémiologiques et la confrontation de certaines données techniques prouvent que les progrès accomplis en matière de lutte contre les poussières sont réels et que les procédés adoptés sont efficaces, d'autant plus, il est vrai, que l'évolution sociale conduit à une diminution de la durée d'exposition par réduction du nombre de Journées travaillées. Il est maintenant possible de garantir la santé des futurs travailleurs après un nombre raisonnable d'années de service au fond (20 à 25 ans au moins) si, à l'avenir les empoussiêrages ne dépassent pas ceux qui ont été obtenus en moyenne ces deux dernières années, dans les conditions particulières du Bassin de Campine. 59 fio Pneumoconioses de catégories M2 et M3 + ••• "•/"o Prévalence -50^ 1950/60 40 30 1969/70 20 1974 1976 10 j... "*' courbef . « cible (objectif) 10 15 20 25 30 Years of service undorgroundÀnnées de travail au fond Pie. 1 - Courbes épidémiologiques - Mineurs de °harb0n du B a s s ^ de Campine (Belgique) 61 Epidemiología de la n^umoconiosis en las explotaciones de carbon de Campine. Belgica G. Degueldre (Belgica) El presente trabajo, después de presentar algunos datos acerca del yacimiento explotado, describe brevemente los métodos de extracción y análisis de polvo utilizados habitualmente. Teniendo en cuenta la concentración, la naturaleza y la granulometria de las partículas captadas, se especifica el significado de esas determinaciones de la cantidad de polvo en el aire comparándolas con los valores obtenidos por medio de los diversos aparatos gravimétricos selectivos empleados en las minas de Europa Occidental. ^Se hace una clasificación de las explotaciones subterráneas según las prescripciones reglamentarias vigentes y se describe la evolución de la prevención técnica siguiendo las variaciones de las concentraciones medidas en los tajos durante las operaciones de arranque desde hace unos quince años. Se describe más adelante el estado sanitario del personal» la prevalencia e incidencia de la neumoconiosis se expresan en çorcentajes del personal que trabaja en el interior según las diferentes clases de antigüedad. En relación a la situación en los años 1959/1960, se comprueba que el riesgo de presentar una imagen radiológica de tipo nu, Enu..., es actualmente alrededor de 20 por ciento menor para quienes tienen diez años de trabajo en el interior y cerca de cinco veces menor para quienes tienen 25 años de trabajo en el interior. Las perspectivas son, pues, tranquilizantes para el futuro denlos jóvenes que, indemnes al comienzo, comienzan o están por comenzar el oficio de mineros. 62 PECULIAR ASPECTS OF THE NATURAL HISTORY OF CHRONIC BRONCHITIS IN COAL MINERS A. MINETTE Institut d'Hygiène des Mines, Hasselt, Belgium The epidemiologists usually base the definition of chronic bronchitis on a clinical entity characterized by chronic cough and phlegm production, for more than 3 months a year for at least 2 years (6). In fact many pneumologists have insisted for many years in different countries that the clinical evolution of the disease is characterized in a not negligible number of cases by dyspnea complaints or a broncho-obstructive pattern from the very beginning of its evolution (3) (17) (34). Recently Fletcher et al (15) published the results of a long-term longitudinal epidemiological survey supporting these views. In miner's bronchitis a high frequency of dyspnea complaints was described by several authors (1) (21) (24) (37) (38) (41). However, the functional mechanism which may support these complaints do not clearly appear in many cases of simple pneumoconiosis (1) (29) (39) (42). On the other hand, one might express some doubts on the reliability of the finding of an excess of dyspnea complaints when the attention of the patients can be focused on their symptoms for particular reasons. Some authors advocate that financial moti- vations could have an influence on the prevalence of dyspnea on account of compensation preocupations (8) (10). Moreover, purely psychological circumstances, as for instance the fixation of the miners' relatives on the disability in this occupation, could also provide an explanation for at least a part of this excess (38). 63 Nevertheless, we found previously in a group of 1234 coal miners hospitalized with bronchitis complaints a definite excess of dyspnea, in comparison with patients with chronic cough and phlegm without dusty antecedents, even in the absence of pro- gressive massive fibrosis and of compensation problems (26). In Great Britain, Morgan et al, studying 29,984 coal miners, also pointed out the high prevalence of dyspnea in a large sample of this population (31). Otherwise, the bad prognostic value of the dyspnea complaints is well known in the literature (22), whereas the aetiology of this symptom remains unclear and is obviously not univocal in coal miners. It seemed therefore of great interest to proceed to a careful examination of the prevalences and causes of chronic cough, sputum and dyspnea, in the coal miners in our country. In this paper, we summarize the results obtained in a study performed in the coal mining area of Belgian Limburg where large numbers of coal miners and matched controls employed in other dusty and nondusty occupations were compared (29). MATERIAL AND METHODS Two transversal surveys were conducted by the same team at the St. Barbara Institute of Lanaken at a few years' interval (27) (28). In the first survey 204 representative cases of a group of 247 coal miners selected by alphabetic order on the population registers of the village of Lanaken were compared to 197 other €A workmen matched for age and economic status, and who were representative of the different professions exercised in this residence (part A of Table I). Since the yearly pollution level was on the average low in the different parts of the village no bias could be expected from that point of view when matching the coal miners with their controls. The estimation of the pollution was made by using an SF apparatus according to the rules edicted by the CEC (7). For SO, we took as upper limit for the low pollution 3 3 50/ig/m , and as lower l i m i t for the high pollution 100jug/m • 3 3 For smoke those limits were 20/ig/m and 50/jg/m . These limits are more severe than the index of Douglas-Waller (14). In the second survey (part B of Table I) we examined 1,060 representative coal miners regularly at work at the coal face in two collieries situated in areas with low and high degree of atmospheric pollution! 599 of them were at work in the first area and 461 in the second. In both mines results of periodic dust counts at the coal face were at disposal (13). They did not differ in that regard (29). During the same period we examined all the workmen of two steel works who were exposed to the same low and high levels of pollution as the coal miners. This study involved 1,284 workmen at work in the five divisions of the steel works located in the area with low pollution, and 1,218 men in 3 divisions of the steel works situated in the high pollution area. The technical aspects and standardization of the methods used for the surveys had been discussed in detail before in an extensive monograph (29). All the surveys were performed by using the short 65 questionnaire (12) of the European Coal and Steel Community (ECSC), completed by measurements of vital capacity (VC), of one-second forced expiratory volume (FEV.), and by chest X-rays (35 cm x 35 cm) in every subject. The spirometrie measurements were done according to the criteria of the ECSCi 3 measurements were performed in each subject, the highest value being taken as the real value¡ the calculations of the expected values were done according to. the ECSC prediction formula (25)t The chest X-rays were performed according to the prescriptions of the ILO (4). In the first survey we also carried out provocation tests with acetylcholine, according to a standardized method involving the inhala- tion of a constant dose of acetylcholine by every subject (9) (30). The coal miners were matched with their controls for age and tobacco use. For the matching by age we used 5-year categories. For the smoking habits we choose a classification in 4 groups when comparisons of symptoms were made. Indeed, in previous standard- ization studies we found that such a classification gives more reproducible results than a ranking according to the number of pack-years (29). Category I comprised all the non-smoking subjects. They had either never smoked or only very occasionally but without inhaling the smoke; in fact none of these subjects had smoked more than 0.1 pack-year. At the other end of the scale, Category 4 comprised all heavy smokers. These had smoked at least 10 cigarettes a day with inhalation for 10 years or more till the moment of the examination, with a maximum tolerance of 1 month in that respect. Category 2 comprised all the subjects who always smoked without inhaling, whatever the kind of product smoked 66 (cigarette, cigar, pipe). In Category 3 we ranged all the other subjects i i.e# all the men who had smoked with inhalation, without reaching the duration and intensity of the smoking habits characterizing Category 4. For some particular comparisons involving linear correlation studies between different factors we needed a continuous numerical scale for the smoking habits, and we used a pack-years classification. RESULTS 1. ESTIMATED RISKS FOR RESPIRATORY SYMPTOMS IN COAL MINERS AND CONTROLS In Table II we give the estimated risks for chronic cough, sputum, dyspnea grade 2 and some characteristic grouping of these complaints for all the coal miners aged 35 to 54 years from both surveys. The coal miners were matched case by case with steel workers for their age, smoking habits, socio-economic status and general pollution exposure. There was an important excess of dyspnea complaints in coal miners. Moreover, in this group dyspnea appeared more frequently as an isolated symptom than in the controls. 2. FACTORS INFLUENCING THE COMPLAINTS IN COAL MINERS 2.1. Pneumoconiosis Table III summarizes the relations observed between the complaints and the grade of pneumoconiosis in the coal miners from the village of Lanaken. The mean smoking habits of the X-ray groups were similar. They varied from 9.86 pack-years to 11.15 pack-years in the different X-ray categories. None of these small differences appeared . 67 to be significant when the categories were compared two by two. The average weight was also practically similar in the different X-ray groups. The weight was expressed by reference to the expect- ed value according to the formula of Lorenz (35), the expected weight being equal to 50 + 0.75 (T - 150), where T represents the height in cm. The mean weights were 101%, 104%, 107%, 106%, 99% of the expected values for the different X-ray categories going from 0 to B + C. None of these means differed significantly from the others when compared two by two. On the contrary, there were some differences between the mean ages of some groups. The coal miners in group B + C were on the average significantly older than those of the other groups (54 years, p^-.05), whereas the ages weœ comprised within a small range going from 37 years to 43.2 years in the other groups: p>.05 when compared two by two. Table II shows that the simple association of chronic productive cough without dyspnea was absent in the X-ray groups 0 and 0/1 aged 37 and 42.6 years respectively. This association appeared only in some cases in group 1 aged 37 years¡ its prevalence went down when pneumoconiosis progressed and became null when massive fibrosis was present. On the contrary, dyspnea as an iso- lated symptom without cough or phlegm was already present in a small proportion (12%) in group 0. The prevalence of this symptom increased abruptly at grade 0/1 and remained relatively stable beyond this stage till the categories B + Ci only for grade 2 was this percentage somewhat higher(50%), but this isolated result may have been fortuitious. The association of the 3 symptoms increased while pneumoconiosis progressed, and its maximum prevalence was reached in the group with massive fibrosis B + Ci on account of 68 the mean age and tobacco use in the different categories this could not be explained by heavier smoking habits, but we cannot exclude the influence of age. Table IV gives the respective proportions of the different complaints in the 200 coal miners aged 30 to 39 years examined at the coal face in the second survey. In this study, we did not ob- serve X-ray categories higher than 2/2. However, here again, we found a definite difference in prevalence of dyspnea, but not of chronic productive cough between grade 0 and the onset of simple pneumoconiosis. 2.2. Influence of cigarette smoking Figure 1 gives a schematic representation of the effect» of smoking by comparing 3 groups of coal miners i a first group comprising only non-smokers living in a non-polluted area, another group of heavy smokers in the same area and a third one of heavy smokers living in a residential area with high pollution levels. Figure 1 also gives the results of a similar comparison in steel workers. All groups were matched for age as indicated in the methods i they comprised only subjects aged 30 to 44 years. The general trend of the comparison is strongly suggestive of a difference in prevalence of dyspnea complaints between nonsmoking coal miners and steel workers of the same age living in a low pollution area. Butthe prevalences for cough and chronic phlegm production were not significantly different between these groups. Figure 1 clearly indicates that smoking habits have a significant effect on cough and phlegm production in both coal miners and steel workers. But tobacco use had no effect on the 69 frequency of the dyspnea complaints. Adding the influence of a general pollution exposure to tobacco use produces a definite higher prevalence of chronic productive cough and dyspnea in coal miners. But air pollution seemed to be without additional effect in smoking steel workers. 2.3. Length of exposure at the coal face For this study the subjects were divided into 4 agespecific categories and matched for their smoking habits. All these groups were further subdivided into 5 categories according to length of exposure at the coal facei 0-4 years i 5-9 years, 10-14 years, 15-19 years and >20 years. Neither in the first nor in the second survey could we find a significant relationship between this length of exposure and the prevalences of chronic cough, chronic sputum or dyspnea. In fact, we must point out that the numbers of subjects were too small in the different sub-groups cited above to allow valid comparisons to be made in that respect. For instance, in the second survey, which concerned the largest total numbers in this investigation, the number of non-smokers from the low pollution area were 16, 50, 39 and 21, respectively, in the 4 age categories. In the heavy smokers groups those numbers were 15, 48, 52 and 37. It is quite understandable that further division of those small groups into 5 sub-categories according to length of exposure would give too small figures for valid statistical evaluation. 3. RELATIONSHIP BETWEEN SPIROMETRY AND BRONCHITIS SYMPTOMS IN COAL MINERS In the first survey, 64 coal miners from the 204 men of 7o the whole group complained of Isolated dyspnea. From these 64 cases, 10 (16%) had a FEV.,/VC ratio smaller than 60%. On the contrary, we found In the whole group 21 coal miners with chronic productive cough and dyspnea, 10 (48%) of them showing this bronchoobstruction pattern. The difference in that respect was signifi- cant (p < .01). It is also interesting to stress that a similar trend was found by analysing the results of the acetylcholine tests. Of 21 subjects with chronic productive cough and dyspnea, 13 (62%) gave a positive response to this test, whereas this was the case in only 12.5% of the 64 subjects with isolated dyspnea (p<c .01). DISCUSSION The lack of relations found between the length of exposure at the coal face and the prevalence of bronchitis symptoms disagrees with recent findings of British authors (33). However, this contradiction could be only apparent. Indeed, the mean age of our coal miners groups was lower than in the British groups, and we mentioned above results suggesting that age could play by itself a role in the onset of bronchitis complaints. On the other hand, the size of our groups was perhaps too small to allow the detection of an effect of chronic exposition to coal dust (23) (36). An interesting finding of our investigation is the abrupt increase in the prevalence of dyspnea observed beyond stage 0 in both surveys. This fact is strongly suggestive of an aetiological role of pneumoconiosis in the onset of dyspnea complaints in coal miners. However, the constant prevalence of the complaints of 71 Isolated dyspnea beyond stage 1 to stages B + C In the first survey could provide an argument against such aetiology. It is interest- ing to point out that chronic cough and phlegm production without dyspnea do not seem to be influenced by the grade of pneumoconiosis. But such relation seemed to be present when considering chronic productive cough associated with dyspnea. Those figures could agree with the hypothesis that cough and expectoration are not directly related to pneumoconiosis, but appear later than dyspnea, frequently when the latter is already present. In this way most of the cases with cough and phlegm would at once be associated with dyspnea, anyway more frequently than this is the case in bronchitis from a non-dusty origin. According to the results mentioned in figure 1, we would suggest that smoking has a major influence on the onset of cough and sputum. In that respect, we must also stress that in the first survey we did not observe in the village of Lanaken any coal miner complaining of chronic cough associated with phlegm production in the group of nonsmokers younger than 40 years. Figure 1 seems to suggest that the general pollution could intervene in coal miners by producing a synergistic effect with tobacco use on the occurrence of these symptoms. Such synergism did not appear to exist in steel workers. These different pathogenic mechanisms could provide an explanation for the natural history of the respiratory disability resulting from chronic bronchitis in coal miners. They explain three main facts i 72 the relatively low prevalence of the cases with productive cough without dyspnea in the young coal miners under 40 years t the relative constancy of the percentages of coal miners with isolated dyspnea when simple pneumoconiosis and age increase; the frequency with which chronic cough, sputum and dyspnea are present at once in association In coal miners at a relatively lower age than in subjects with bronchitis from a nondusty origin. An explanation for the high prevalence of dyspnea complaints in coal miners from the initial stages of simple pneumoconiosis could be the diffuse focal emphysema of Gough (20) as well as the high prevalence of diffuse stenotic and ectatic bronchiolitis lesions from the very beginning of the diseases (18) (19). At more advanced stages, above all in the case of condensations, it is well known.that emphysema plays a major role in the causation of shortness of breath. Moreover, in our cases of massive fibrosis, age and past smoking habits were higher» therefore we cannot exclude that the same mechanisms as those intervening in bronchitis from a non-dusty origin have contributed by themselves to a further increase of the dyspnea prevalence. The lack of relationship between isolated dyspnea at the first stages of simple pneumoconiosis and the spirometrie figures is anyway an argument for a different pathogenesis for this clinical type of dyspnea and the dyspnea complaints associated with productive cough observed at higher age and when more pronounced smoking ante- 75 cedents are present. Similarly, the lack of relationship between the frequency of isolated dyspnea and the responses rate to acetylcholine as compared with the rate found in coal miners with productive cough, is also an argument for a particular specific pathogenesis for this symptom. In that respect, it is interesting to add that the role of the cigarette similarly appeared to be different when considering the isolated dyspnea and the whole of all the dyspnea complaints inclusive those associated with chronic cough and expectoration. Such discrepancy was strongly suggested by the results of the first survey when making an age-specific comparison of the prevalence of both types of symptomatology in light smokers and heavy smokers (Table V ) . The figures of this table clearly suggest that above 30 years of age tobacco could increase the prevalence of all patterns of dyspnea, whereas this phenomenon was not observed when considering only the cases with isolated dyspnea. However, on account of the small number of cases, a valuable statistic evaluation could not be performed. Therefore, it seems reasonable to explain by specific mechanisms most of the cases of isolated dyspnea at the initial stages of pneumoconiosis. Rasmussen et al suggested that lesions of the small peripheral arteries in simple pneumoconiosis could provide an explanation for this (37).' Other authors described an alteration of the CO diffusion in pinhead and micronodular pneumoconiosis (2) (16). They explained these abnormalities by a reduction of the diffusion capacity and by a restriction of the 74 capillary bed. Of course, small-airways obstruction due to bronchiolitis, as suggested by increases in closing volume, or changes in elastic properties due to fibrosis or emphysema could also provide an explanation for the dyspnea. More recently Smidt emphasized that an increase of total lung volume may frequently occur in workmen with long-lasting occupational antecedents in dusty atmospheres (40). Similar facts were also reported by Morgan et al (31). Such phenomena could explain an excess of dyspnea complaints at the early stages of pneumoconiosis. 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JACOBSEN M., RAE S., WALTON W.H. and ROGAN J.M. : The relation between pneumoconiosis and dust-exposure in British coal mines. in : Inhaled Particles III. Proc. of an International Symposium organised by the British Occupational Hygiene Society in London, 14-23 September 1970. Surrey, England, W.H. Walton, Unwin Brothers Ltd. The Gresham Press Old Working, 1971, 903-919. 24. JAMES R.H. : Distribution of pulmonary ventilation in disabled Southern West Virginia coal miners. - Amer. Rev. resp. Dis., 1970, 101, 715-720. 25. JOUASSET D. : Normalisation des épreuves fonctionnelles respiratoires dans les pays de la Communauté Européenne du Charbon et de l'Acier. - Poumon, 1960, 16, 1145-1159. 26. MINETTE A. : Rôle de 1'empoussiérage professionnel dans la production des bronchites chroniques des mineurs de charbon. - in : Inhaled Particles III. Proc. of an International Symposium organised by the British Occupational Hygiene Society in London 14-23 September 1970. Surrey, England, W.H. Walton Unwin Brothers Ltd. The Gresham Press Old Working, 1971, 873-881. 27. MINETTE A. : Results of an epidemiological survey on bronchitic symptoms in the male population of a Belgian mining community. in : Ecology of chronic nonspecific respiratory diseases. International Symposium, September 7-8, 1971, Warsaw, Poland, Warszawa Panstwowy Zaklad Wydawnictw Lekarskich, 1972, 87-96. 28. MINETTE A. : Contrat CECA N° 6244-0O/2/O34 : Enquête dans des bassins industriels à forte densité de population sur les lieux du travail et en dehors de ceux-ci. - Commission des Communautés Européennes, rapport final, 1975. 78 MINETTE A. : Apport ôpldémiologique â l'étiologie de la bronchite chronique des mineurs de charbon. - These pour l'obtention du grade d'agrégé de l'enseignement supérieur. Université Catholique de Louvain, Faculte de Médecine, 1976, 203 p. MINETTE A., MARCQ M. and GEPTS L. : Prognostic value of a positive acetylcholine test regarding VC and FEV. in coal-miners with a history of chronic bronchitis. - Bull, europ. Physiopath. resp., 1978, 1^, 167-175. MORGAN W.K.C., BÜRGESS D.B., LAPP N.L. and SEATON A. : Hyperinflation of the lungs in coal miners. - Thorax, 1971, 26, 585-590. MORGAN W.K.C., LAPP N.L. and MORGAN E.J. : The early detection of Occupational lung disease: - Brit. J. Dis. Chest, 1974, 68, 75-85. MUIR D.C.F. : Pulmonary function in miners working in British collieries : epidemiological investigations by the National Coal Board. - Bull. Physiopath. resp., 1975, 1_1, 403-414. ORIE N.G.M., SLUITER H.J., de VRIES K., TAMMELING G.J. and WITKOP J. : The host factor in bronchitis. - in : Bronchitis. An International Symposium. Groningen 27-29 April 1960. Assen (Netherlands), VanGorcum, 1961, 43-59. PERLEMUTER L. : Bilan métabolique d'une obésité. - in : Problèmes actuels d'endocrinologie. - Paris, Ed. J. Hazard, Masson et Cie, 1973, 7-15. RAE S., WALKER. D.D. and ATTFIELD M.D. : Chronic bronchitis and dust exposure in British coalminers. - in : Inhaled Particles III. Proc. of an International Symposium organised by the British Occupational Hygiene Society in London 14-23 September 1970. Surrey, England, Ed. W.H. Walton, Unwin Brothers Ltd., The Gresham Press, Old Working, 1971, 883-894. RASMUSSEN D.L., LAQEUR W.A., FUTTERMAN P., WARREN H.D. and NELSON C.W. : Pulmonary impairment in Southern West Virginia coal miners. - Amer. rev. resp. Dis., 1968, ¿8, 658-667. SLUIS-CREMER G.K., WALTERS L.G. and SICHEL H.S. : Chronic bronchitis in miners and non-miners : an epidemiological survey of a community in the gold-mining area in the Transvaal. - Brit¿ J. industr. Med., 1967, 24, 1-12. 79 39. SLUIS-CREMER G.K., WALTERS L.G. and SICHEL H.S. : Ventilatory function in relation to mining experience and smoking in a random sample of miners and non-miners in a Witwatersrand town. - Brit. J. industr. Med., 1967, 24, 13-25. 40. SMIDT U. : Chronische Bronchitis und Lungenemphysem. Klinisch epidemiologische Untersuchungen über die Bedeutung beruflicher Staubexposition. - Thieme Copythek 1975. VIII. Stuttgart, Thieme-Verlag, 198 p. 41. ULMER W.T., REICHEL G. und WERNER U. : Die Bronchitis des Bergmannes. Untersuchungen Normalbevölkerung und bei Bergleuten. Die belastung und der Einfluss des Rauchens. pa th. Gewerbehyg., 1968, 25, 75-98. 42. WORTH G., MUYSERS K. and SIEHOFF F. : Derzeitiger Stand der Kenntnisse über den Einfluss von Grubenstäuben auf die Funktion des bronchopulmonalen Systems. - in : Symposium BronchitisEmphysem, Stresa, 21.-22. April 1966, Europäische Gemeinschaft für Kohle und Stahl, Hohe Behörde, Schriftenreihe Arbeitshygiene und Arbeitsmedizin Nr. 5, Luxemburg, 1967, 27-47. 8o chronisch obstruktive zur Häufigkeit bei der Bedeutung der StaubInt. Arch. Gewerbe- TABLE I GROUPS OF THE FIRST :SURVEY MINERS TRANSPORT MISCELLANEOUS * LISTED RESPONSES ELIMINATED* 247 112 101 222 (90%) 112 (100%) 90 (90%) 18 2 3 EXAMINED GROUPS ** 204 110 87 The elimination occurred on account of heart diseases or X-ray abnormalities of a non-pneumoconiotlc nature. ** The non-responders and eliminated persons did not differ statistically from this examined group. B. GROUPS OF THE SECOND SURVEY I. COLLIERIES! REPRESENTATIVE GROUPS OF COAL GETTERS IN TWO COMPANIES 1. In a low polluted colliery 2. In a highly polluted colliery II. t 676 listed workmen, 599* examined (88%) i 575 listed workmen, 461* examined (80%) STEEL WORKERS « ALL WORKERS OF TWO COMPANIES 1. In a low polluted steel works i 1284 listed workmen, 1175* examined (91%) 2. In a highly polluted steel worksil218 listed workmen, 1150* examined (95%) * It has been established that the non-responders did not differ from the others from the point of view of bronchitis. 81 TABLE III PREVALENCE OF VARIOUS ASSOCIATIONS OF COMPLAINTS WITH RESPECT TO PNEUMOCONIOSIS IN 204 COAL MINERS LIVING IN A LOW POLLUTION AREA* PREVALENCES OF NUMBER OF CASES BY RADIOLOGICAL CLASS MEAN AGE (YEARS) ALL COMPLAINTS DYSPNEA ALONE COMPLAINTS COUGH PHLEGM COUGH PHLEGM DYSPNEA 0 i 25 37 16% 12% - - 0/1 i 49 42.6 47% 35% - 10% 1 (q.r) i 49 37 41% 25% 8% 4% 2 (p.q.r) • 44 42.1 64% 50% 5% 7% 3 (p.qi r) i 27 43.2 56% 26% 4% 22% 30% _ 50% B + C * i 10 80% 54 See text i Material and methods. 85 TABLE IV RELATIONSHIP BETWEEN RADIOLOGICAL STAGE AND PREVALENCE OF COUGH, PHLEGM AND STAGE 2 (ECCS) DYSPNEA IN 200 NON-SMOKING COAL MINERS AGED 30-39 YEARS RX stage 0 RX stage 0/1-2/2 NUMBER OF CASES WITHOUT COMPLAINTS 142 80 (56%) 58 22 (3B%) 84 CHRONIC COUGH CHRONIC PHLEGM DYSPNEA 2 (7%) 14 (10%) 30 (21%) 6 (10%) 7 (12%) 25 (43%) 10 ac. o (9 ¡Ö 5 Si 5 Ol «•1 o «a- < VI <>» •o 01 < oc 3 O < I- o. 3 o> o >• Q X VI u 01 Jí gi. VI •o *» C .e « °1. r*I — *-» (\j I >( > « «! éf ~ *r to ~v m IM (N w ID > z ui I — •- O Z £ </) CE UJ Z O f- •»*» 10 » o z: z UO «/> UJ O < > tu ce ¡h en co s c Q OC O O O < 01 >> 3 u. o 3 O •C 4-> •c » U CM N» CO w ^ «J- #p co »r *- v. co w *f m CM CO »^ » — tn CD CM 01 o •"•"II. < o r^ il- ce. OL CM C o c/> O VI M ID 01 Jt *> OL SL ^* «»# X m Smo 2 fm p 10 •O V) C 01 io vi VI VI « 01 13 O VI E »VI 01 I ¿X 85 *í CM o ^ CM «r A« CO m \ CM CM ~ 1 C£ a ia i— = > *« CVJ co ¡S «a- ai >,<n in «n O «tk O J O •^ in o SE •^ vt<t~ ai •r- 01 O-rOn/l ai «i «- > H U H CO £o g —'JE V ai *t- 2 «t _i O -J •— O u a. o o O =¿ C/î <-> W >• r* •-< Dl* IO vi c t. ai o o <»••O IO TJ í. ai o ai JJZTJ O ^ *> «1 IO • C E O-O 3 O <*.«*• ¿3£o </i z u on-> 01 C "-JJCT.O u 3 IO C vi ai ai » c « U3 T - -U -* f-i i/> S Q- LU _> »« »« 00 fes < O Q 86 Caracteres particulares de la bronquitis crónica de los mineros de carbón. A. Minette (Bélgica) Las enfermedades pulmonares crónicas no específicas de los mineros de carbon pueden deberse a diversos factores que actúen conjunta o suceslvamentei uso de tabaco, edad, polvo, contaminación ambiental, factores constitucionales. El autor efectuó dos encuestas por sección transversal sobre esos problemas utilizando el cuestionarlo del Medical Research Council y la Comunidad Europea del Carbón y del Acero. En la primera encuesta examinó a 204 mineros de carbón residentes en una zona de poca contaminación (Lanaken, Bélgica) y seleccionados al azar por orden alfabético en los registros de población. Los comparó con una muestra representativa de sus esposas y con 178 testigos residentes en la misma ciudad y cuya edad y condición socioeconómica fueran paralelas a las de los sujetos estudiados. En la segunda encuesta comparó 1.251 mineros de carbón que trabajaran regularmente en el tajo con 2.502 obreros de fundición. Se efectuaron regularmente controles del polvo en el lugar de trabajo, así como de la contaminación del medio ambiente. Se comprobó que el factor predominante para la aparición de tos productiva en los mineros de carbón era el hábito de fumar cigarrillos. Tratándose de sujetos menores de 40 años, el autor no halló siquiera casos de tos productiva crónica entre los no fumadores, en ausencia de una fibrosis masiva u otra anormalidad toráxlca correlacionada. La exposición crónica al polvo de carbón y la exposición prolongada a niveles elevados de contaminación pueden tener efectos sinergéticos con el consumo de cigarrillos sobre la aparición de una tos crónica con expectoración. Según lo observado, la contaminación no tiene efectos sobre los trabajadores de las fundiciones. La conclusión general es un poderoso fundamento para la opinión de que la definición de la bronquitis crónica basada únicamente en la presencia de tos crónica y expectoración no abarca toda la gama de la enfermedad. En muchos casos de bronquitis llamada "del minero de carbón", la disnea aparece ya en las fases precoces de la enfermedad. .87 \ DUST EXPOSURE AND PNEUMOCONIOSIS AT 10 BRITISH COAL MINES M. Jacobsen Institute of Occupational Medicine, Edinburgh, United Kingdom 1. INTRODUCTION A large scale prospective study of British coal miners was begun 25 years ago. The aim of this "Pneumoconiosis Field Re- search" was to determine how much and what kinds of dust cause (coal workers') pneumoconiosis, and to establish what environmental conditions should be maintained If mine workers are not to be disabled by the dust they breathe. An Interim answer to the first of these questions ("how much dust causes pneumoconiosis") was provided in 1970. That work,which was based on 10- year periods of observation at 20 collieries, demonstrated a correlation between the radiological changes observed at the collieries and the colliery-average coal face dust concentrations measured during the 10-year periods. The results were used to estimate long-term risks of developing coal workers' simple pneumoconiosis In relation to different average dust concentrations, and this Information provided the scientific background for decisions on new coal mine dust standards which were Introduced In Britain at that time. (Jacobsen et âl, 1970). A further 10-year period of observation has now been completed at ten of the collieries included In the study. Analyses to date of the results have concentrated on seeking answers to two questions i ( 1) Are the newly acquired data consistent with the estimates of îrm d u s t - r e l a t e d pneumoconiosis 89 - 2risks that were made ten years ago using results from only 10-year periods of observation? (11) Is there any evidence that the chance of developing coal workers' simple pneumoconiosis Is Influenced by the quartz content of the coal mine dust to which men are exposed? Preliminary results from this work are summarised here. 2. 2.1 METHODS Dust exposures Since the start of the project, records have been kept of the time worked by each man In different occupational groups at the collieries. The average dust concentrations associated with these occupational groups have been determined from a programme of dust sampling close to the men at their places of work and during travelling time underground. Dust concentration measurements during the first 10-year phase of the studies were made with the Thermal Precipitator and were expressed at the number of respirable particles per cubic centimetre of sampled air. These measurements were con's verted later into mass concentration units (mg/m ), as described by Dodgson et al. (1971). A more intensive programme of dust sampling has been pursued during the latter 10-year 9o - 3period, using MRE gravimetric dust samplers. The sums of products, 5(time worked In occupational group x average concentration in occupational group), provide measures of exposure to respirable dust for each individual during the course of the research. Additionally, exposures to dust before the research began were estimated from occupational histories obtained at interviews with the men. The number of years spent in any one of six broad categories of coal mining activities, were converted into working hours and were multiplied by the mean dust concentrations for occupational groups corresponding to these activities, as determined in the first 10-year period of measurement. Thus there were available estimates of cumu- lative exposure to respirable coal mine dust, from entry to the industry up to the time of the latest medical surveys. The exposure units are gram-hours per cubic metre of sampled air (gh/m ). 2.2 RadioloRlcal data The latest medical surveys included full-size (anteroposterior) chest x-rays of 2,600 miners who had been examined initially 20 years earlier. Serial chest radiographs, spanning the two consecutive 10-year intervals, were examined by each of five physicians experienced in the radio91 - 4 logy of pneumoconiosis. A H 7,800 films were classified separately^ independently and in random order by each reader, according to the ILO U/C International Classification of Radiographs of Pneumoconioses (ILO, l97l). Additionally, each reader classified the three possible pairs of films from each man, side-by-side on the viewing box. 3. RESULTS Correlations between dust exposure and simple pneumoconiosis Figure 1 shows the proportions of men with at least the earliest signs of simple pneumoconiosis (category 0/1 or more), as determined from the five readers' average results, in relation to cumulative dust exposures. Both methods of assessing the radio- graphs (independent classifications, and side-by-side readings of film-pairs) demonstrate very similar relationships between this measure of radiological response and the exposure index. (Most of the results reported below are based on the independent, separate film classification). Differences between readers, using the independent classifications, are illustrated in Figure 2 in terms of the proportions of men whose radiographs were classified as showing category 2 or 3 of simple pneumoconiosis. Evidently, the differences between readers are greater than the differences between reading methods, but it is clear that each reader's results show convincing correlations with dust exposures. High correlations with dust exposure were obtained also with readers' radiological scores averaged over men in various dust exposure ranges. latter scores are semi-quantitative representations of the 92 (The - 5"amount of pneumoconiosis" seen on a chest radiograph. They are based on the 12-point scale used for classifying the profusion of small rounded opacities). The confirmation, in Figures 1 and 2, of the correlation between radiological signs and the measures of dust exposure as determined in the Pneumoconiosis Field Research, is important for several reasons. ( 1) Earlier results (Jacobsen et al, 1971) were based on only ten years' observation in a selected group of coal face workers. The work reported now Is not restricted to face workers and the period of research has doubled. ( li) Dust measurements made during the first 10-year phase of the project were respirable particie-count concentrations, which were converted retrospectively to mass concentration units. All dust measurements during the last ten years have been made directly with gravimetric samplers. (ill) The 1970 Interim study was confined to correlations between radiological changes over 10-year periods and average dust concentrations during those periods. The cumulative dust exposures described above refer to individuals and they include estimates of exposure before the research began. 3.2 Dust exposure and Incidence of simple pneumoconiosis The correlations demonstrated In Figures 1 and 2 are between radiological signs as observed at the latest medical surveys 95 - 6and cumulative exposure to dust since joining the industry. The time periods during which these exposures were accumulated varied. These measures of response cannot therefore be Interpreted as disease incidence rates, since such rates refer to the new occurrence of events during a specified time Interval; and it is incidence rates which are of interest when considering disease risks and hygiene standards. The quotient obtained by dividing an individual's cumulative dust exposure by the time period during which that exposure was accumulated is a measure of the average dust concentration experienced by that individual. This alternative index of exposure was used in a series of analyses aimed at expressing pneumoconiosis risks as a function of both exposure time and average dust concentration. Efforts were made also to take into account previously observed variations in risks resulting from similar exposures to dust at different collieries (Walton et al, 1977). Figure 3 illustrates one such equation. The curve describes the estimated increases in the probability of developing category 2/1 or more simple pneumoconiosis with exposure to increasing mean concentration of respirable dust over 61,000 working-hours. This time period has been selected to illustrate the relationship because it approximates to a 35-year working-life at the research collieries in the late I960's. Thus the new results made be compared approximately 94 - 7with those published previously (the dotted line In Figure 3, from Jacobsen et al, 1970). The latter estimates of 35-year risks were derived from less comprehensive data, and using a different mathematical approach (Jacobsen, 1975). It appears that the earlier predictions underestimated 35-year workinglife risks by one to two percentage probability units. 3.3 Differences between collieries The equation Illustrated in Figure 3 makes provision for variations In probabilities at the same exposure depending on whether a man worked at colliery T, at colliery Q, or at one of the other eight collieries studied. These variations are large and they dwarf the differences between the two analyses Illustrated In Figure 3. At colliery T (now closed) pneumo- coniosis risks were some five to six times higher than the average results shown on the graph) at another colliery (Q) they were about l/9th of the average. Yet the mean concentration of airborne dust to which men were exposed In colliery T (2.9 mg/m ) was lower than the corresponding figure for colllery Q (4.4 mg/m ). Moreover, the average quartz content of the mixed dust exposures at colliery T was the same as that for all 2,600 men considered (5.0%); at colliery Q however It was higher (6.4%), The analyses to date have failed to explain these marked colliery-associated variations which have been considered also In previous publications (Walton et al, 1977). Atten- tion Is drawn to them again now because of the Implicit 95 difficulty in generalising from average results obtained at only ten collieries. Quartz in mixed coal mine dust Several attempts have been made in the past to determine whether or not relatively small quantities of quartz in mixed coal mine dust affect the pneumoconiosis. chance of developing coal workers' Earlier studies of British data have failed to reveal a clear-cut effect (Jacobsen et al, 1971; McLintock et ali 1971 i Walton et al, 1977). Similar negative findings have been reported from the Ruhr coal field in Germany (Reisner, 1977). Greatly improved information about the quartz content of dust sampled in the research collieries has been obtained recently, using infrared spectroscopy. The accumulated results were therefore re-examined in detail. In principle, it is conceivable that the relationships between radiological signs and mixed coal mine dust (Figures 1, 2 and 3) are merely reflections of an effect wholly or mainly due to the quartz content of that dust. (This hypothesis is tenable a priori because,although percentage quartz in the dusts varied, in general, high exposures to mixed coal mine dust tended to be associated with high exposures to quartz dust (r = 0.76). In fact, such an Interpretation of the data is contra-indicated. Analyses similar to those summarised above, but substituting quartz for mixed dust as a variable, did not explain the responses satisfactorily. This confirms a previous generalisation from British epidemiological data 96 - 9which asserted that "the most Important single variable determining the incidence of simple pneumoconiosis is the cumulative mass of the respirable fraction of all airborne dust to which individuals are exposed" (Jacobseni 1973). The conclusion refers, of course, to dust exposures of the kind observed at the collieries. The quartz level in these exposures averaged 5% and rarely exceeded 10%. Yet it is possible that varying levels of quartz in the dust, even in this range, influences the pneumoconiosis risk in addition to the effect of the main environmental factor exposure to mixed dust. This possibility was explored ex- . tensively using the newly acquired data, by considering whether or not variations in quartz exposures helped to explain the residual variability in radiological results, unexplained by the equation defined in the caption to Figure 3. pattern emerged from these studies. No sensible Figure 4 illustrates one such negative result. However, there is evidence that some Individuals who were exposed to relatively high average quartz concentrations over 10-year periods did show unusual changes on their chest radiographs . In addition to the 2,600 miners whose life-time exposures to dust have been discussed above, there were 1,750 men who had worked at the same collieries only during the latter 10-year period. Among the total of 4,350 men there were 46 who showed two or more steps of radiological change on the 12-point simple 97 - 10 pneumoconiosis scale over the 10-year interval. (This is based on the concurring judgement of at least three of the five filmreaders, using side-by-side assessments of the film-pairs concerned). It was possible to select a "control" miner to match 42 of these "cases". The "controls" showed no radiological change over the same time interval and using the same radiological criterion. Matching factors were (a) colliery; (b) whether the "case" was aged more or less than 35 years at the start of the 10-year period) and (c) whether the "case's" initial radiograph had been classified as category 0/1 or higher at the earlier survey. Subject to these constraints, "controls" were selected so as to minimise the difference ("case" - "control") in cumulative exposure to mixed dust up to the final medical survey. Figure 5 shows the distribution of differences ("case" - "control") in the quartz content to which the men were exposed during the 10-year intervals. Two thirds of the miners with unusual radiological changes had been exposed to more quartz dust than the men without radiological changes with whom they had been paired. The asymetry of the distribution of differences (Figure 5) is unlikely to be due to chance (P< 0.005). 4. CONCLUSIONS The general correlation between coal mine dust exposure and simple pneumoconiosis, which was first demonstrated eight years ago, is confirmed unambiguously. Long-term risks were probably underestimated in the earlier 98 - 11 work by one to two (percentage) probability units. 3 There are large variations between collieries in medical responses to similar dust exposures. They dwarf the differ- ences between alternative statistical approaches to the data, and they make it difficult to generalise safely from the results. 4 The variations in pneumoconiosis risks between collieries are not explicable in terms of different quartz levels at the collieries. Nor is there any general pattern in the results which might indicate that quartz exposures amounting to less than ten percent of mixed coal mine dust affect the probability of developing coal workers' simple pneumoconiosis« 5 However, there is evidence from the data that a few men may re-act unfavourably over relatively short (10-year) intervals to coal mine dust with a high quartz content. The Penumoconiosis Field Research is financed by the British National Coal Board. All involved in this project thank the miners, their Unions, and the Colliery Managers for their willing co-operation during the past 25 years. We are grateful also to Drs. J.G.Bennett, J.Burns, J.A.Dick, D.J. Thomas, and J.S.Washington who classified the radiographs. Mrs. E.H.Copland and Mr. J.F.Hurley did most os the statistical work reported above. 99 -12- REFERENCES DODGSON, J., HADDEN, G.G., JONES, C O . and WALTON, W.U. (1971). Characteristics of the airborne dust in British coal mines. Inhaled Particles III. Ed. tf.H. Walton, pp 757 - 76*1. In: Unwin, Old Woking, Surrey. ILO, 1.972. ILO Ü/C International Classification of Radiographs of Pneumoconioses, 1971. ^rev,^ ILO Occupational Safety and Health Series No. 22 Geneva. JACOBSEM, M. (1973). Progression of coalworkers' pneumoconiosis in Britain in relation to environmental conditions underground. In: Proceedings of the Conference on Technical Measures of Dust Prevention and Suppression in Mines, Luxembourg 1972. JACOBS EN, M. (1975). PP 77 - 93. CEC,Luxembourg. Effects of some approximations in analyses of radiological response to coalmine dust exposure. In: Recent Advances in the Assessment of the Health Effects of Environmental Pollution. _1_, 211 - 229. CEC, Luxembourg. JACOBSEN, M., RAE, S., WALTON, W.H. and ROGAN, J.M. (1970). standards for British coal mines. New dust Nature (Lond.) 227, ^5 - '»'»7. JACOBSEM, M., RAE, S., WALTON, W.H. and ROGAN, J.M. (1971). The rclatisr. between pneumoconiosis and dust exposure in British coal mines. Inhaled Particles III. Vol. 2, pp 903 - 919. In: Ed. W.H. Walton. Unwin, Old Woking, Surrey. McLINTOCK, J.S., RAE, S. and JACOBSEN, M. (1971). The attack rate of Progressive Massive Fibrosis in British coalminera. Particles III. Vol. 2, pp 933 - 952. In: Inhaled Ed. W.H. Walton. Unwin, Old Woking, Surrey. REISNER, M.T.R. (1977). Erkenntnisse epidemiologischer Unter- suchungen fUr den Schutz vor Stauberkrankunßen. 1oo Glückauf, 113, ?1 - 26. WALTON, W.U., DODGSON, J . , MADDEN, G.G. and JACOBSEN, M. ( 1 9 7 7 ) . The e f f e c t of q u a r t z and o t h e r non-coal dusto i n c o a l w o r k e r s ' pneumoconiosis. ¿n: I n h a l e d P a r t i c l e s IV. Vol. 2 , pp 669 - 690. Ed. W.H. Walton, Pergamon, Oxford. PAIRED ("SIDE-Bi-SIDE") READINGS PEROENTAOE WITH CATB30KT 0 / 1 OB HTftHER 100 # 15?) 2 » 23> Ï0Û SEPARATE ( INDEPENDENT) READINGS r 350 FIGURE 1 CDITOLATIVE DDST EXPOSURE ( g V " ) FIGURE 1. COMPARISON OF TWO READING METHODS Average results from five film-readers'" classifications of radiographs of 2 6OO coal miners, by mean of cumulative exposures to mixed respiratile coalmine dust from entry to coal mining to time of radiological survey; grouped data. loi FIGURE 2. COMPARISON OF FIVE READERS« CLASSIFICATIONS Separate (independent-randomised) classifications of radiographs of 2 600 coal miners, by mean cumulative exposures to mixed respiratile coalmine dust from entry to coal mining to time of radiological survey; grouped data. •"> — t PERCENTAGE WITH SIMPLE PNEUMOCONIOSIS CATEGORY 2 OB HIGHER ¿AVERASE OF FIVE READERS' IÜDEP5IIDEH7 CLASSIFICATIONS CDMOLATIVE DOST EXPOSURE FROM ENTRY TO INDUSTRY TO TIME OF X-RAI THOUSANDS OF HOURS x FTWTHE ? a*,'»3) 1o2 ESTIMATES OF PROBABILITIES 0 7 DEVELOPIW CATHJOHT 2 OR MORE SIMPLE PNEUMOCONIOSIS OVER AN APPROXIMATELY 35-YEAR WOHKIÑO-LIFE AT THK COALFACE Based on weighted averages of estimates for c o l l i e r i e s T, Q, and the other eight c o l l i e r i e s considered a s a group, with t a 60.9 thousand hours. The equation of the curve i s : l o g i t (P) = -2<».6028 + 2.i»352 Cln(r)] - 1.9059 (Q) • 2.3'»27 (T) • f.3222 Cln(t)] where x = mean dust concentration, t a exposure time, in thousands of hours, and Q, T are dummy variables representing colliery effects. The above coefficients are averages of results from five separate fits, by maximum likelihood, to data from five film readers' independent-randomised classifications. Weights used to obtain the curve illustrated were the proportions of men from the collieries in the sample studied, i.e., (161/2 600) for colliery T, (326/2 600) for colliery Q, and (2 136/2 600) for the other eight collieries. Based on statistical extrapolation of radiological change ' over 10 years; from Jacobsen t£ al (1970: 1971) 1o3 PROBABILITY ( * ) OF DCTELOPIHO CATEBOHÏ 2 / 1 OH MORE 10 7 / / / - / / / / / b 1 2 3 I I I <t 5 6 7 MEAN OUST CONCENTRATION (mR/aT) FIGORE ? 1o4 riaURI k. DIFFERENCES (R) BETWEEN OBSEHVED AMD PREDICTED PERCENTAGES OF MEN WITH CATEGORY ?. OR MORE SIMPLE PNEUMOCONIOSIS, BY MEAN PERCENTAGE QUARTZ IN MIXED COALMINE DUST EXPOSURE Data grouped In order of percentage quarts; 130 aen per group. Observed percentages from average of five readers' independent-randomised classifications. Predicted percentages from equation defined in caption to Figure 3. (The absence of a systematic pattern in the residuals (R) with respect to percentage quartz indicates that percentage quartz is not nssociated with residual variability unexplained by the equation.) I- R («) -*-+ 10 • KKAN PERCFimWE QUARTZ IN DUST EXPOSURES naoRB * 1o5 FIGURE 5. DIFFERENCES ("Case" - "Control") IN PERCENTAGE QUARTZ IN EXPOSURE TO MIXED COAIMNE DUST OVER TET! YEARS "Cásea": two or more positive steps of change over 10 years on the 12-point radiological scale; "Controls": no radiological change over 10 years on the 12-point radiological scale. +7 QTFT>:SE"CS I» P:-:3CSNTA':K w m z I « MIXED COALMINE DUST KXKT.URK: (CASE-CONTROL) 2 $ CASES HAD MORE •5 % QUARTZ THAN CUKTROLS +1» •3 +1 O O O -1 o • • • o o ó o o o 14 CASES HAD LESS % QUARTZ THAN CONTROLS -2 FK5URE 5 106 Exposición al polvo v neumoconlosla en diez minas del carbon en Gran Bretaña M. Jacobsen (Reino Unido) Los recientes estudios médicos realizados por el Servicio Británico de Investigaciones en materia de Neumoconlosis comprendían exámenes radiológicos de 2.600 mineros del^carbón, examinados inicialmente 20 años antes. Se calculó la exposición al polvo respirable en las minas de carbón durante intervalos de 20 años a partir de los registros del tiempo trabajado por cada obrero en grupos profesionales en las diez minas examinadas y los promedios de concentraciones de polvo respirable medidas en esos grupos. La exposición al polvo anterior al primer estudio fue calculada a partir de las historias profesionales, reconstituidas mediante entrevistas con los interesados. Cinco médicos experimentados en la utilización de la Clasificación Internacional de Radiografías de Neumoconlosis de la OIT/UICC llevaron a cabo evaluaciones repetidas de las correspondientes radiografías. Los primeros resultados de esos estudios revelan una relación indudable entre las estimaciones de exposición cumulativa al polvo de carbón respirable y las distintas interpretaciones que cada uno de los cinco médicos ha hecho de las radiografías llevadas a cabo en los estudios más recientes. Se han hecho comparaciones entre los nuevos resultados y los de un análisis realizado anteriormente de los resultados basados en^exposlciones medidas únicamente durante diez años. Las últimas estimaciones específicas, basadas en la dosis de polvo, de los riesgos de neumoconlosis del carbón de categoría 2 o más simple que se va desarrollando a lo largo de la vida de trabajo son 1 ó 2 por ciento (unidades de probabilidades) superiores a las predicciones anteriores. Esta diferencia es insignificante comparada con las Inexplicables variaciones en la relación de dosis a efecto según las minas. 1o7 . I N D I C E S E S S I O N II B»B»Basss993SS9Saltasffl38iiisi I Kl.Adr lenza Rapporteur II B.Klendez An Epidemiologic study of silicosis in Brazil, from a survey of patients in tuberculosis hospitals. III G.Cornea., A.Chechen., A.9en Kheder., Silvia Gabor., I. El Rlekkl. La silicose dans une mine de spath-fluor de Tunisie. IV J.Prenafeta., Clayton., and R.Sepulveda. Variability in the X-Ray diagnosis of early Silicosis. V K.Chiyoteni., Ken-ichi Saito. Excess lung cancer risk in silicotic cases, under hospital care-preliminary report. VI J.Prenafeta., A.Valenzuela., G.leyton., S.Vlllagran. Epidemiological survey and prognostic evaluation in Silicosis. 1o9 EVALUACIÓN EPIDEMIOLOGICA DE LAS NEUMOCONIOSIS Ï OTRAS ENFERMEDADES RESPIRATORIAS DE NATURALEZA OCUPACIONAL EN VENEZUELA Manuel Adrianza H. Ministerio de Sanidad y Asistencia Social (MSAS) Amílkar Toçrealba. Ministerio del Trabajo (MT) Erich Schmidt. Ministerio de Sanidad y Asistencia Social (MSAS) Catherine Ernould. Conicit Francisco Fuenmayor. Instituto Venezolano de los Seguros Sociales (IVSS) Maximiliano Acosta. Ministerio del Trabajo (MT) INTRODUCCIÓN: Es obligatorio el abordaje epidemiolàgico de un problema de salud ocupacional, toda vez que la epidemiología está definida como disciplina para el diagnóstico de la comunidad, y además, como una de las ciencias que sirve para solucionar los problemas de la Salud Pública y de la Medicina Preventiva. ( H ) . El análisis del riesgo de exposición del cual depende di rectamente la morbilidad, puede ser simple o complejo según el pro-blema y las ciroustancias que lo rodean. En el caso de las neumoconiosis en nuestro país, el problema podría circunscribirse en una primera etapa a la silicosis y a la asbestosis para los polvos inor_ gánicos, a la bisinosis, a la bagazosis y otros síndromes respirato rios de la hipersensibilidad reactiva parenquiraatoaa o bronquial p¿ ra las exposiciones orgánicas. Cuando este estudio se enfrenta a un desarrollo industri, al de carácter explosivo como el nuestro, y con una dinámica apreta da a un lapso corto de 20 años aproximadamente y cuando el proceso va acompañado del incipiente desarrollo simultáneo de los otros pro cesos de organización del sistema, como por ejemplo los registros y las estadísticas, teniendo estas que sufrir en sus comienzos de la misma imperfección, generan obstáculos para el valor de las aproximaciones en las inferencias matemáticas. 111 El presante estudio se hizo con la aplicación de las metodologías de salud, clínica, radiología, exámenes funcionales del pulmón, aplicadas al diagnóstico de neumoconiosis en primer lugar y, en segundo lugar y con bastante validez para el diagnóstico de £ tras perturbaciones respiratorias como la bronquitis crónica ocupacional, separada o no de los efectos del hábito de fumar, el asma bronquial y los síndromes obstructivos respiratorios además del enfisema pulmonar. (12) Representa un corte transversal del diagnóstico de salud respiratorio para los años 1977 y primer semestre de 1978, en áreas industriales expuestas a los riesgos de asbesto y sílice entre los polvos inorgánicos; bisinosis, bagazosis y otras patologías respira torias de las industrias del tabaco y pulpa de papel entre los ries. gos orgánicos. El programa continuará hasta la cobertura de todos los riesgos y de toda una muestra suficiente por clase de riesgo. El estudio especial para la población minera subterránea, se realizará durante el primer trimestre del año 1979. Representa el resultado del diagnóstico de salud aislado del diagnóstico ambiental, por la imposibilidad de realizar el moni toreo pulvígeno simultáneo a las investigaciones médicas en todas las plantas estudiadas. Analizando pues, todo el problema a través del conocimien to de las limitaciones, restó solamente enfrentar la decisión del estudio y la misma se hizo, a sabiendas de las posibles fallas esta. dísticas, con el objeto de obtenec a la mayor brevedad posible, un punto de referencia epidemiológico para los programas de prevención de hoy y del mañana. El criterio para la selección de exámenes de esta evalua_ ción epidemiológica, siguió estas pautas: 1o) Evitar pérdida innece_ saria de tiempo. 2 o ) No ofrecer riesgos ni inconvenientes al sujeto examinado.3?) Tener el valor de predicción para estadios tempranos. í°) Bajo costo. 5o) Factibilidad de relacionarlo cuantitativamente al daño de salud. 6 ) Alta validez, es decir, sensibilidad y especi 112 fieldad para reflejar la situación verdadera que se investiga, Apa£ te de estas consideraciones metodológicas, fue necesario adoptar cierta flexibilidad en las normas y pautas de acuerdo a las condiciones de terreno inherentes a toda investigación de campo con equi pos electrónicos instalados en Unidades Móviles. Por ejemplo, prefe rir el estudio del grupo de las concreteras de la zona metropolitana por las posibilidades de hacer todos los exámenes en nuestro sex vicio con óptimas condiciones de operabilidad. La historia clínica, y el examen físico especializado, salvo algunas excepciones, se reja lizó por personal médico especializado y se utilizó, como orienta— ción, la ficha para polvos orgánicos del Servicio de Empleados y productividad del Reino Unido y las orientaciones del EMAS (15) CHIEF EMPLOYER MEDICAL ADVISERS del Reino Unido, cortesía del Dr. M. Greenberg y se revisaron además los barridos específicos de Medicina del Trabajo, del Plan de Higiene y Seguridad del Trabajo en Espa ña. Los exámenes de función pulmonar se realizaron con equipos Jaeger, especialmente instalados para las condiciones de terreno y fueron diariamente sometidos a calibraciones, despula de cada traslado. Se practicaron determinaciones espirométricas, curva flujo-volumen y pruebas de difusión con monóxido de carbono en estado de equilibrio y la realización e interpretación correspondió a personal médico y técnicos especializados. Los estudios radiológicos se hicieron con placas 14x17 pulgadas en las instalaciones fijas hospitalarias para los casos de la zona metropolitana y para la población testigo con placas 100x100 milímetros con cámara Odelca en una Unidad Móvil en las plantas industriales y explotaciones mineras del interior del país. La interpretación la hicieron con doble lectura en la gran mayoría de los casos, médicos y neumonólogos clínicos de larga experiencia. Se uti, llzaron las técnicas y las recomendaciones de la Organización Internacional del Trabajo aprobadas en Bucarest, en el año 1971, con oca alón de la IV Conferencia Internacional de Neunoconiosis, pero, se simplificó el dato final en el estudio de las Neumoconiosis a cuatro (4) posibilidades: normal, sospechoso, positivo y otros diagnÓ£ ticos. Todo el estudio fluorofotográfico se hizo a "boca de fábrica", 113 excepto las empresas de la zona metropolitana. Para el diagnóstico de las perturbaciones respiratorias se estudiaron otros signos radiológicos de sobredistensión pulmonar con o sin signos de enfisema imarcado. El proceso general de la Encuesta siguió los lineamieri tos del Informe Técnico N° 528 de la Organización Mundial de la Sa. lud (15) (1973) y las evaluaciones estadísticas se hicieron con el asesoramlento de expertos de la Organización Internacional del Tra_ bajo y la Dirección de Estadística Laboral del Ministerio del Trabajo de Venezuela. Los recursos presupuestarios para la adquisición y el mantenimiento del programa se obtuvieron del Departamento de Tuberculosis y Enfermedades Pulmonares de la Dirección de Salud Pií blica del Ministerio de Sanidad y Asistencia Social; y con el apo.^ yo regional de las Comisionadurías de Salud de los estados'Aragua, Carabobo, Yaracuy, Lara, Falcón y Miranda, se realizaron las opera ciones de terreno en esas Entidades Federales. PROCEDIMIENTO: Por lo menos 7 cifras se deberían conocer en nuestro medio para manejar la evaluación de los problemas respiratorios ocupacionales y especialmente conióticos, al saber: 1) Población trabajadora en general expuesta a todos los riesgos laborales. (17) (Tabla 1-1). Figura 1-1. 2) Población trabajadora expuesta a riesgos respiratorios. (Ta-bla 1-2). Figura 1-2. 3) Población trabajadora expuesta a contraer neumoconiosis. (Tabla I-3) (xx y xxx). Figura 1-3. 4) Población trabajadora expuesta a ciertos riesgos específicos entre las neumoconiosis por actividades económicas. (Tabla 1-3y Tabla 1-4). Figuras 1-3-1, 1-3-2, 1-3-3. 1-3-4. 1-3-5 y Figura 1-4. y Tablas 1-5 y 1-6. 5) Población mayormente expuesta de acuerdo a las áreas d.ej. proceso de explotación o producción para separar obreros y emplesi dos en una primera etapa. 114 No es aconsejable definir la población por puestos de riesgos debi do a la intensa rotación de puestos de trabajo que ha caracterizado este proceso entre nosotros desde sus etapas iniciales. 6) Ciaras del Universo de trabajadores y obreros de los primeros grupos seleccionados y 7) Cl£ra de la muestra examinada y de la morbilidad proveniente del muestreo. 7-1 Morbilidad respiratoria. 7-2 Morbilidad neumoconiótica propiamente dicha. Para mejor comprensión resumimos en las Tablas 1-5 y 1-6, renglones específicamente relacionados con el primer muestreo de la encuesta. DATOS DEMOGRÁFICOS DE LA POBLACIÓN TRABAJADORA; La tabla y la figura 1.1 recoge los datos de la poblact ón trabajadora en Venezuela desde los años 1968 al 1977 ambos i n — cluídos. La línea de puntos representa la curva de tendencias con unas estimaciones para los años 1982 y 1987 de .... 4-. 565.324trabajadores y 5.560.990 trabajadores; respectivamente. Estos mismos datos se representan en la Tabla 1.1.. Figura 1.1. Es de hacer notar el gran incremento en la población trabajadora en Venezuela por un aumento en el cuatrienio 1973-1977 de 678.857 un promedio anual de 169.7H.por año frente a un promedio anual de crecimiento en el quinquenio anterior 1968-1973 de 89.117 trabajadores. Es decir, el promedio anual de crecimiento de la población trabajadora en el cuatritenio 1973-1977 es el doble que en el quinquenio anterior 1968-1973. De acuerdo con las estima ciones anteriormente realizadas este promedio, anual pasará a ser de 172.265 en el quinquenio 1978-1973 y de 161.870 trabajadores en cuatrienio 1983-1987 de seguir el mismo ritmo de crecimiento que el encontrado hasta ahora. 115 Tobia 1.1 POBLACIÓN TRABAJADORA VENEZUELA (*) C¿i*a.A t¿t¿mada* 116 1-8 I S K | o u. i i e g i! i ! ! Î i-i 117 i Tibia I.I TOTAL POBLACIÓN TRABAJADORA EXPUESTA A ENFERMEPAPES PROFESIONALES RESPIRATORIAS AÑOS TRABAJAPORES 1941 1970 1975 77 I9*tf 1915 C¿4*44 155.49$ M*.315 151.445 154.450 173.924 111.519 191.III 19*.114 - ¿SI.117 153.192 • 141.I9S * 144.445 * 141.712 • 199.417 • itO.Oit * 541,592 • . 3*5.941. • 511.244 * '41t.US * 44t.SU * atinada* 118 \ •z I i *s -s -i -I Ss I c • • -I .B S -I n -6 -g -I -I 3 9 o - 00 8 o ö — 1 — 8 o s 2 S § —r S s 119 Población trabajadora con riesgo profesional respiratorio. En la figura 1.2 se recogen los datos de los trabajadores int¿ grados en las treinta y tres (33) actividades económicas señaladas anteriormente y que son propensas a padecer una afección respiratoria de causas profesional. La línea de puntos representa la curva de tendencia con las estimaciones para los años 1982 y 1987 de .... 320.011 trabajadores y 4-42.316 trabajadores respectivamente. Estos mismos datos se representan en la Tabla 1.2. Figura 1.2. Obteniéndose como promedio asociados de crecimiento para la población afecta de riesgo profesional respiratorio para el quiíi quenio 1968-1973 la cifra de 9.127 y en el trienio 1973-1976 la cifra de 16.529 y unas estimaciones para el quinquenio 1977-1982 y 1982-1987 de 5.364 por año y 24.461 por año respectivamente. POBLACIÓN TRABAJADORA CON RIESGOS DE NEUM0C0NIOSIS: En la Tabla 1.3. se recogen los datos de los trabajadores con riesgos de Neumoconiosis. La línea de puntos representa la curva de tendencia con las estimaciones para los quinquenios 1977-1982 y 1982-1987. Las c¿ fras estimadas para estos quinquenios pueden observarse en la Tabla 1.3. Figura 1.3. De esta misma tabla podemos observar que los promedios anuales de crecimiento de la población trabajadora expuesta a la Neumoconiosis para el período 1968-1973 es de 7.810 trabajadores y de 15.234 para el período 1973-1976 y unas estimaciones para el quiri quenio 1977-1982 de 15.453 trabajadores por año y para el quinquenio 1982-1987 de 21.732 trabajadores por año. Desglozando el Capítulo anterior en los diferentes riesgos específicos obtenemos los siguientes datos. 12o Tabla. 1.3 POBLACIÓN TRA6AJAP0RA EXPUESTA A LAS NBUIWCOUIOSIS S A N O 196 1 9 197 0 1 t 3 4 197 5 6 7 I f • > " TRABAJAP0RE5 ' 0 1 f S 4 Ml 5 6 7 114.til 133.2*7 143.493 14t.476 151.496 163.994 173.191 139.t96 Í09.60Í tlO.403 « ff S. 15« ' fSl.fS« ' tS3.60t ' 169..46* fl7.«7f 306.903 $14.74S 144.5*1 371.437 SI*.555 ' ' ' < ' ' ' Clfuu -ikXJ.ma.Atk 121 \ \ -i .i \ I \ -i \ \ .2 \ \ -5 ; \ E E 1 -I M -I 9 *» S tal "i oc J 5Ï -1 i l OC Ul i o -2 i 1 122 M POBLACIÓN TRABAJADORA CON RIESGO DE SILICOSIS: En la figura 1.3.1 se recogen los datos de la población trabajadora con riesgos de silicosis y que han sido enumerados por actividades económicas anteriormente (parágrafo A.2.1) La línea de puntos representa la curva de tendencia con las estimaciones para los años 1977-1987. Las estimaciones para 1982 y 1987 son de 209.398 y 300.136 trabajadores respectivamente. Estos mismos datos pueden obtenerse en la tabla 1.3.1. figura 1.3.1 Obteniéndose como promedios anuales para la población laboral afecta de riesgos de silicosis las cifras de 5.301 trabaj¿ dores por año para el quinquenio 1968-1973 y de H.623 trabajado— res por año para el trienio 1973-1976 y unas estimaciones para el quinquenio 1977-1982 de 12.661 trabajadores por año y para el quin quenio 1982-1987 la estimación es de 18.197 trabajadores por año. POBLACIÓN TRABAJADORA CON RIESGO DE TALCOSIS; En la figura 1.3.3» se recogen datos de la población trabajadora con riesgos de talcosis y que han sido enumerados por actividades económicas anteriormente (parágrafo 1.2.1). La línea de puntos representa la curva de tendencia de las estimaciones para los años 1977-1987. Las estimaciones para 1982 y 1987 son de 8.949 y 10.660 trabajadores respectivamente. Estos datos pueden observarse en la tabla 1.3.3. Figura 1.3.3. Obteniéndose como promedios anuales de crecimiento para la población laboral afecta de riesgo de Talcosis las cifras de 3Aí trabajadores por año el quinquenio 1968-1973 y un crecimiento negativo para el trienio 1973-1976. Estas cifras negativas resultan del crecimiento negativo del año 1976 respecto al año 1973 ya que en el primer caso la población con riesgos de talcosis es de 6.81¿ trabajadores y de 6.234 para 1976. Estas cifras no se contradicen entre sí si tomamos en cuenta que ellas solo reflejan los trabaja- 123 14 Tabla t.S.I POUACJOU TRABAJADORA EXPUESTA A LA SILICOSIS TRA3AJ Avoues AÑOS 1900 ¿m 1970 11 11 73 14 1915 7« 77 71 7» 1910 II 00 tS $4 /90S ti . *1 * CH>uu 10.440 1 /ICI •7. 0)1 0{.507 9 1.19* 100.215 Í07.Í49 M f. 071 fff.701 IS 1.019 144.09Í • IS 4.990 • H 0.719 • It I.JI5 • 190.051 • to9.J90 • ti 5.5t* • u 1.050 • (S9.000 * ti 9.000 • so 0.1Jé • titlmadcu 124 en tu oc <t z o z -I a §2 Ì2o s ui z 5 lüg < Sg « Í2 IO 2 o ^ -J 5 < = 2 S «o S OC <r ai ? u z 2 111 tlJ « p z S 2 111 bJ OC H 2 Ul o I! H i 125 Tabía f.).3 POBLACtOH TKABAJAVORA EXPUESTA A LA TALCOSÏS AROS TRABAJADORES 5. 095 • 5 514 5 m 6 411 é. 59« i. tu 1 59% 1 105 6 254 1 512 1 IZO t 057 t 344 t 641 9 til 9 591 9 «Jf 10 f f j 10 060 C¿¿*<u tttA.ma.dcu 126 • • • • • . « • • • t s e i i * S M S S l-I i i 1 I i 127 dores existentes en las actividades afectas de riesgo y que por razones económicas y otr.as en 1976 bajó a la cifra mencionada. Las estimaciones del crecimiento anual para el quinque-nio 1977-1982 son de 287 trabajadores por año y de 34-2 para el quin quenio 1982-1987. POBLACIÓN TRABAJADORA CON RIESGO DE BISIHOSIS; En la figura 1.3.4 se recogen datos de la población trabajadora con riesgos de Bisinosis y que han sido enumerados por actividades económicas anteriormente (parágrafo A.2.1) Las líneas de puntos representan la curva de tendencia con las estimaciones para los años 1977-1987. Las estimaciones para 1982 y 1987 son de 25.098 y 26.697 trabajadores respectivamente. Es tos datos pueden observarse en la tabla 1.3.4. figura 1.3.4. Obteniéndose como promedios anuales de crecimiento para la población laboral afecta de riesgos de Bisinosis las cifras de 669 trabajadores por año para el quinquenio 1968-1973 y de 19 trabsi jadores por año para el trienio 1973-1976 y unas estimaciones para el quinquenio 1977-1982 de 624 trabajadores por año y para el quinquenio 1982-1987 la estimación es de 721 trabajadores por año. POBLACIÓN TRABAJADORA CON RIESGO DE BAGAZOSIS: En la figura 1.3.5. se recogen datos de la población tr¿ bajadora con riesgos de Bagazosis y que han sido enumerados por actividades económicas anteriormente (parágrafo A.2.1) La línea de puntos representa la curva de tendencia con las estimaciones para los años 1977-1987. Las estimaciones para 1982 y 1987 son de 15.698 y de 20.640 trabajadores respectivamente. Estos datos pueden observarse en la tabla 1.3.5. figura 1.3.5. Obteniéndose como promedios anuales de crecimiento para la población laboral de riesgos de Bagazosis las cifras de 686 tra- 128 Tabla, 1.3.4 • P08LACJ0U TKABAJAVORA EXPUESTA A LA UJ$i:WS13 A H0 S TKABAJAVCRLS u 9t$ 15 Ut H. 9ét lé. 0S4 It 541 11, ni 19 i$i 11. ut 11. tti H r97i ti. 544 ti 149 ir«m tt 4tt ts 19$ 15 655 U 41t ts m ts 954 U 491 (UiJuu 129 t*U.aado4 V) ui I 2 é a 2 o 2Q os u O u. S3 z bl •s > 5 «o ^ a. X ñ ° 111 o O (E bl CD J V M ö Sgl H u2 bl Z •2 CE 2 U O -i 1 1 1 r S i i ! ! ! 13o .8 tabla. 1.3.5 VOÔLACICH TRABAJADORA EXPUESTA A LA SAGAZOSlS * « O S TRAEAJAVOP.tS 1961 «9 »970 71 7f 75 74 1975 7« 77 71 7t 1940 «I II 15 1« 1915 14 «7 5.615 4.716 5.415 5.1*1 7.1*7 7.04« 7.rjt 4.411 «.44» 9*091 9;«47 10.71r -17,««4 tt.tu • 15.691 14.141 14.159 17.511 19.015 20.640 • • ••• • • •: - * C^iMU tMtA.ma.dM 131 • • • • 6 S i i \ V) ÜJ K • i \ 3 0. ! m S -I B -i LA MEDA OCONI » «s 1 883 -i RÍ 2 4 W 3 Ü- lai « ¡ ? UJ * fc w >- ° fi g gs L Sil N 82 1 .fe . ' • : E lì S ^e SP 5j , : | I |-.. j . : j . . j . U u ! |||3 « : -i » ! e " * 2 bl . : :.:•; * 2 etr e <t a. U) o -i I 132 TABLA 1-4 POBLACIÓN TRABAJADORA EXPUESTA A 1A MOKIUUIS CRONICA PROFESIONAL ENFISEMA ASMA ÛCtiPACICNAE V OTRAS AFECCIONES RESPIRATORIAS AROS TRABAJADORES lut 1 11.043 ti.041 Ì4.UI IS.«54 14.421 ti.átS ff.930 I7.5t0 ti.509 tí.719 Í4.44I U.tlS «4.114 - 3<r.f53 3*.339 34.414 37.1»! 39.»94 4Í.7« 45.^91 é\1 I97Í > 71 7S 7¡\ H1 W Ji 11l 7íi - H1 H1 191(i 11 11t f. 1 H1 IUI i »i\ 1)r C¿{4&4 133 tAtimadcLA • • • •• • • *. • • • Hb ¡ó.;:;:. \.:rb: p!::\ V i •' i l . . . . : : • . v , L it;i : LÜ £j o< \ s "T" e S o 1Jft bajadores por año para el quinquenio 1968-1973 y de 341 trabajadores por año para el trienio 1973-1976 y unas estimaciones para el quinquenio 1977-1982 de 921 trabajadores por año y para el quinqué nio 1982-1987 la estimación es 1.388 trabajadores por año. POBLACIÓN TRABAJADORA COH RIESGO DE BRONQUITIS CRONICA PROFESIONAL. ENFISEMA. ASMA PROFESIONAL Y OTRAS AFECCIONES RESPIRATORIAS: En la figura 1.4 se recogen datos de la población traba jadora con riesgos de Bronquitis crónica profesional, enfisema, a¿ ma profesional y otras afecciones respiratorias y que han sido enu meradas por actividades económicas anteriormente (parágrafo A.2.1) La línea de puntos de esta figura representó la curva de tendencia con las estimaciones para los años 1977-1987. Las e,s timaciones para 1982 y 1987 son de 32.339 y 45.891 trabajadores respectivamente. Estos datos pueden observarse en la tabla 1.4. figura 1.4 Obteniéndose como promedios anuales de aumento para la población laboral afecta de los riesgos mencionados las cifras de 1.316 trabajadores por año para el quinquenio 1968-1973 y de 1.295 trabajadores por año para el trienio 1973-1976 y unas estimaciones para el quinquenio 1977-1982 de 1.910 trabajadores por año y para el quinquenio 1982-1987 la estimación es de 2.710 trabajadores por año. RESUMEN DEL UNIVERSO A ESTUDIAR: Todas las 42 actividades que aparecen en los cuadros de los sectores públicos y privados con riesgos, en general ligados a la inhalación de polvos orgánicos e inorgánicos en explotaciones minera e industriales, hacen un Universo de 309.382 trabajadores (7Í de actividad lextractiva y el resto de actividad manufacturera) en 6.817 establecimientos industriales de 5 o más trabajadores repartidos en dos grupos: uno de empleados, el cual totaliza 70.355, 135 o sea el 25? y el restante, el más numeroso y más expuesto formado por 239.027 obreros. Así pues, el Universo circunscrito al mayor riesgo de exposición sería de 239.027 personas, repartidas 154.293 en el área inorgánica y 84.738 en el área orgánica. La población más expuesta del área inorgánica se agrupa en 21 actividades de ajn bos sectores totalizando 71.716 personas y se reducen menos en el índice de riesgo de exposición por la variedad de factores que están en juego en la producción de la respuesta respiratoria a estos agentes (ver Tabla 1-5 y 1-6). PLANTEAMIENTO DE LA ENCUESTA: El muestreo seleccionado se hizo combinando la lógica de la representación obligatoria de la actividad, agrupación, grii po y subgrupo para los riesgos de mayor jerarquía en la salud pública venezolana para los sexos, edades, tiempo de exposición esp¿ cífica en individuos escogidos al azar, dentro de las agrupaciones previamente hechas de acuerdo al riesgo específico. (18) (19) La primera etapa de la encuesta seleccionó 14 actividades, nueve de ellas del área de polvos inorgánicos con un universo de 2:.762 obreros y cinco del área de polvos orgánicos con un universo de 32.8.4 obreros. El total de ambas áreas es de 58.586 obreros de un grupo de 73.296 trabajadores. El total de obreros re presenta el 80Í del total de trabajadores y el 25Í de todo el Universo Nacional y el 35? de los grupos seleccionados para todo el estudio. (Ver Tabla 1-6) GRUPO CONTROL; La escogencia del grupo control fue precedida de una ajn plia discusión de todas las condiciones necesarias para condicionar la validez de las inferencias estadísticas para todos los para metros de la investigación. La primera condición fue elegir un gru po humano no sometido previamente a contaminación intramural o extra-mural. De acuerdo a esta condición la ciudad de Coro ofreció las mejores garantías, debido a que esa ciudad no tiene un desarro 136 1 1 , 1 OAlllSOa' m m m • 10 M 5 -HOldCOC 8 • S < OAI1V01M M S •> «OHIO 4 IO » • •™ 3 • 0 OD 10 XVMOl - 1 'M 0 » 0) X«WJ1 S 10 W 0 S «9 «g =' 8 e 5 •i n 0 « •Mill» MIC e •* S n N 0 0 n M 0 1 NOICfMM OIXIK •» •» -o • • * «NC* N • ** S - a •• O 01 'ICI* '9OM1CI0 lVNMOM OAUICOd ¡0 0 °i N CD 0) a Z 3. 3 10 s «_ s S r» 0 s • N M » M * • < $ 10 N •S 6 S * « a= u < J Î S á>- 137 0 * VIDRIO como FARERI PORCE N> 8 N -Mill« MIC EORA 8l • N NTERA N« S, 5 ALTER. FUNCIONA LES S DIABNOSTICO X EXPL. CL INICA 3 0 2« U > Ma a * 5 £ oe» Z «* s. »- Z Ilo industrial. Pero, posteriormente, cuando el análisis de la nraes tra de casos estudiados en Coro mostró una sorprendente cifra de procesos obstructivos especialmente asmáticos al cual se asociaban alteraciones frecuentes de la columna vertebral de tipo escoliosis, fue necesario hacer otra muestra testigo y se escogió la población de Caucagua en el estado Miranda, donde existían las mismas condicio nes relativas a la ausencia de industrialización. Como hecho de importancia la población sana respiratoria de Caucagua se caracterizó por presentar una aparente incidencia aumentada de procesos vasculares del pedículo aórtico en los estudios radiológicos especialmente. ANÁLISIS DE.LOS RESULTADOS; Tabla 4-1. Muestra de Obreros con Riesgos de Silicosis. Se estudiaron un total de 64.O obreros expuestos en mayor o menor grado al sílice libre, pertenecientes a 18 empresas cuyas at: tividades incluían la extracción,, utilización y/o transformación de minerales con un mayor o menor contenido de sílice. Se clasificaron en cuatro grupos según el riesgo teórico. Grupo I Canteras y piedras con 92 obreros Grupo II Alfarería, loza y porcelana con 147 obreros Grupo III Cemento con 189 obreros Grupo IV Vidrios y fundición con 212 obreros. El último grupo con 212 obreros tiene la particularidad de asociar el riesgo silicótico, dado por la utilización de arenas de alto contenido de sílice, el gran stress térmico que caracteriza a las industrias de vidrio y la fundición. La proporción de fumadores varía en conjunto desde un 27? a un 10% del número de obreros de cada empresa y el tiempo de exposjL ción medio es superior a cinco años. La Tabla 4.-1, expresa los resultados encontrados en el es_ tudio de esta muestra. El análisis de estos resultados y su compara- ci 3 8 < OAUltOrf N veos IO OAIXVtlH < o S S * «111« WC XVNOl + T « 0 d XVNOl s •1 •» t» s 8 j ft* Sü ALTER. FUNCIONALES ' » H I V WS "F tomo •> MOItlMIO - W O OIXIN 0 IO o ICI« M N N uto e fi e ? S •M •» 19 O O M m r- •. 0AI1IS04 • • * OAIXVMN n = 2 K VMV p *> •0 o z •• 0 _ * Ë 139 u¡2« I-- Si JfcA. ción con el grupo testigo nos conduce a las siguientes conclusiones: 1) Mayor incidencia de los diagnósticos específicos (silicosis) en los grupos con mayor riesgo teórico, canteras, piedras, vidrios y fundición y recíprocamente mayor incidencia de diagnósticos inespecíficos e independientes del riesgo en los grupos II y III de alfarerías, lozas, porcelanas y cemento. 2) Las alteraciones funcionales tienen la misma significación en los cuatro grupos. 3) En la exploración clínica nos encontramos los mismos resultados que en el capítulo "diagnósticos", mayor incidencia de patología en los grupos con menos riesgos específicos, pero, asociado a factores de microclima laboral. 4) La radiología tampoco aporta especificidad a ninguno de los grupos entre sí pero sí en relación con la muestra testigo. 5) Excepto para lo que se refiere a la exploración clínica, (afectada siempre de gran subjetividad por no ser el mismo médico en todos los casos) y más concretamente a la exploración del área ORL, las diferencias en los demás parámetros, entre los grupos estudiados y el grupo testigo son altamente significativas (prueba x 2 de Pearson). Tabla A-2. Influencia del Tiempo de Exposición Para estudiar la influencia del tiempo de exposición clasificamos la muestra de 637 trabajadores en tres grupos: Grupo I Tiempo de exposición menor de 1 año (123 casos) Grupo II Tiempo de exposición entre 1 año y 10 años (345 casos) Grupo III Tiempo de exposición mayor de 10 años (169 casos) Los resultados obtenidos en este análisis nos permiten concluir lo siguiente: a) La morbilidad específica por silicosis aumenta significativamen te cuando se incrementa el tiempo de exposición hasta alcanzar, 14o *n co dtoe o m M CM OAI1V03N « IO '«JAI* c. CM « N » CO co m S M CM Ñ » 0> = • g o n o OIXIH o - o XS3V IO n CM N ço S CO m * CM CM »ne» * 10 CM •o •• s co - OAIXISOd N r O 0AUV83N >- 10 10 IO -H 0 NIS COtU.0 NOisnjia ¿CSO » 0 FUMA00RES N» 290 IO M3X1V 141 CO ID CO MUESTRA TESTIS 0 NO FUMADORES N. 89 XVHOl •1 NO NÓSTICO 5 CD m 2 « <3~ 4 O IO FUMADORES N >348 + NIC XVHOl -1 '8 0 ALTER. FUNCIONALES N. S. EXPL. CLINICA N. S. RAOIOLO N. S [vio OAUlSOd 11 ! IO «1 ÜSOC o 0AI1V»» O •O m i i « MIS xvtni + "I 'M "O xvyoi •i •» -o ALTER. FUNCIONALES «M 'H311V <B 4 O » » N N • • * S como S MOMMO IO »1X1H IO 1U» IMO O u p n o r NIC M * • 1VHN0M N N M •» "O IO • »dí» n 'MOW o OAUICOd N « I TALCO N« 36 EXPL. CLINICA i OAUICOd 142 0 LOGIA g* 0AI1II04 IO M <ttos IO «1 OAIlVtJN ID oc« dill* EXPL. CLINIC N. S. 4 S • IO XVMOl o o -KJ11V Nit (M N tomo t- NOItfMn M oixm O K m N usto 1- 1VNM0N 0> IO ALTER. FUNCI H. S. CO P • l •« -o ¿ S ao s« Nit XVMOl "l 'H 0 •B •» -0 «HIT VN3 0N0H8 Ol IO O M .o OAllltOd O QUÍMICOS N : 44 * SO zz 1^3 el grupo de mayor tiempo de exposición, la importante cifra del 19*. Este incremento se manifiesta también en las alteraciones funcionales, la exploración clínica y la radiológica. c) El análisis estadístico de estas diferencias demuestra que son altamente significativas (p 0,01) excepto en la radiología en donde el nivel de riesgo es menor del 5?. d) Al comparar cualquiera de estos grupos con el grupo testigo las diferencias son también altamente significativas (p 0,01). b) Tabla 4-3. Influencia del Hábito de Fumar Las diferencias entre ambos grupos te significativas (N.S.) y al compararlas con camente son estadísticamente significativas o glones correspondientes al diagnóstico y a la no son estadísticamen el grupo testigo únisea (p 0,01) los ren radiología. Tabla 5-1. Estudio de una Muestra de Obrero con Riesgo de Talcosis El Universo de la población obrera sometida a riesgo de Talcosis se encuentra muy atomizado en pequeñas industrias del ramo de la cosmética por lo que no se ha abordado en esta primera etapa del Programa de Neumoconiosis. En la industria del caucho se estu-dió en una planta un grupo de 36 obreros con alto índice de exposición y los resultados obtenidos se muestran en la Tabla 5-1. Se destaca en la Tabla anterior el gran número de diagnósticos positivos encontrados (17Í) de obreros con patología específica correlacionados con un incremento de alteraciones funcionales restrictivas. Las diferencias con la muestra testigo son altamente significativas (p 0,01). Tabla 6-1. Análisis de una Muestra de Obreros de la Industria Química Se han estudiado un total de UU obreros de dos plantas de industrias químicas relacionados con la industria de pinturas y la fabricación de pesticidas. Estos obreros no están expuestos a un 144 riesgo específico de Neumoconiosis, no obstante el adverso microcli ma laboral en que se desenvuelve su actividad hace presumir la aparición de alteraciones en la esfera respiratoria. Los valores encontrados se muestran en la Tabla 6-1, así como la comparación con la muestra testigo, pudiéndose extraer las siguientes conclusiones: 1) 2) Aumento estadísticamente significativo (p 0,05) de las alteraciones respiratorias inespecíficas y Aumento altamente significativo (p 0,01) de los hallazgos radio lógicos. ANALISIS DE LA MUESTRA DE OBREROS SOMETIDOS AL RIESGO DE POLVOS ORGÁNICOS: Dentro del Universo de 64.738 obreros que están expuestos a riesgos de alteraciones respiratorias por polvos orgánicos, se han estudiado en esta primera etapa un total de 223 obreros, elegidos al azar dentro de los obreros de ocho empresas encuadradas en las s i guientes actividades: Ingenios y refinerías de azúcar Hilados.de tejidos Industria del tabaco Alimentación Artículos de pulpa de madera Enzimas Biológicas - detergentes y papel En este grupo los riesgos específicos característicos son: el algodón que produce la Bisinosis y el bagazo de la caña de azúcar productor de la Bagazosis. Sim embargo, dada la naturaleza or gánica de las materias primas utilizadas predominantemente por estas industrias son bastante frecuentes las alteraciones respiratorias de naturaleza inespecífica, consecuencia de una especial sensibilidad de algunos individuos. Además hoy se sabe que puede existir cierto grado de contaminación con substancias inorgánicas. 145 eoMJ.0 § o Q < oc OAUlSOd dSOS 0AIXV83N U31-1V NtS XVM01 * TMO XVU01 ~i a o cu U311V MS M S0U10 Noierun 8W.XIK i -J.81U o o •» •» o g z 1890 n O "B *n SOAlilSOd o soAumam 5 C 01 w o ^ u J N X U -Î o » N .2 < z 146 TABLA 3.2. Significación estadística de las diferencias y niveles de riesgo al aplicar l a prueba x' de Pearson a los resultados obtenidos e n l a T a b l a 3 . 1 . DIAGNOSTICO RADIOLOGIA O -1 X tu te 3 g g 5 O •*» »-• W te o 3 N o • 1 «a TEXTIL - P«V* »«VOI P«¥>l - xOjOI AZÚCAR - - P'OJOI p<0,OI - - «ESPECÍFICOS - - 1X0,01 - - TEXTIL - P«VOI N. S. - P<0J0I P«V» N.9. AZÚCAR - - P<0,OI p<Qpi - - ,<op, p<0gDi INESPECIFICOS - - - - N.9. - N.S. ita ><ogoi P«W)i 9*0fií - p<OpOI - ALTER. FUNCIONALES EXPL. CLINICA 147 N.S. aso« OAI1V63N 1 ? « n xvuox T 1 M 8 0 aanv S 3 É m n n S fe o IP co M N * F> eT g S 0> N a (D o O o $ «o co o o> £ m oc bi issa » S o 5 J.880 S O ID a » o o * • N CN co «1 o 1 1 M » * 1* M N O IO «0 N - O S o O 0AU.V63N 01 CM N 8 Ï5 IB FUMADORES Grd. I N= 71 «M ÍH8 NO FUMADORES MUESTRA TESTIGO N' 59 0) N o e FUMADORES , Grd. n y HZ N = 39 N OAIllSOd FUMADORES N« 113 * O NO DIAGNOSTICO • • • S! 60J.XIN VN6V N O NOISfUM «t n 2 * * soaio IM $ < z o u z NI8 1 5 » IO S 1 o * MJ.IV NtS » 1 H 0 XVMOi. 1 FUMADORES N-IIO EXPL. CLINICA RADIOLOGIA _i 60HJ.0 OAUISOd Tabla 3-1. Análisis de los Resultados La Tabla 3-1» muestra los hallazgos encontrados en cada uno de los tres grupos que hemos subdividido la muestra. Los diagnósticos específicos fueron 23 casos de Bisinosis (34Í del total de expuestos) y 6 casos de Bagazosis (19Í). Se detectó también una Asbestosis contraída por el obrero con anterioridad al ingreso en la fábrica de alimentos en que se encontraba en la actualidad. En este mismo grupo es de resaltar la alta morbilidad en el grupo de las azucareras (81? de diagnósticos patológicos) con gran predominio en las alteraciones respiratorias inespecíficas (58Í). Así miji mo una alta morbilidad asmática (12$) en el tercer grupo formado por obreros de la industria del tabaco, de la alimentación y de eri zimas biológicas. En el conjunto de las alteraciones funcionales destacamos el aumento de las patologías restrictivas en el grupo de las a. zucareras que se diferencian significativamente con los otros que permanecen sin diferencias entre ellos y sin diferencia con la mues tra testigo. En esta misma característica presenta en la exploración clínica el grupo de azucareras, con un porcentaje muy alto de halla¿ gos patológicos (97Í) de forma análoga no existen diferencias significativas entre los grupos textil, inespecíficos y testigos. En los diagnósticos radiológicos se modifica en parte la situación anterior siendo las diferencias entre todos los grupos estadísticamente significativas excepto al conparar el grupo textil con el inespecífico. Un resumen de lo anterior lo mostramos en la Tabla 3-2, con la significación estadística de las diferencias encontradas al aplicar la prueba x2 de Pearson. La Tabla 3-3» muestra estos resultados al clasificar con juntamente la muestra según el hábito de fumar, eligiendo como testigo el grupo de no fumadores de la muestra testigo anterior. No existen diferencias estadísticamente significativas entre ambos gru 149 i 1 como OAUKOd IO M CM aeoe IO CM M OAUVB3N O tt> NIS XVHOl IO IO NIS A. iL 8 CM IO IO IO H V aanw co » n + -nao xvuoi -i » O 00 o m CO «9 s CO «O conio NOISfldlO IO IO 0Í.XIN U.G3H o u ìeeo O H V 0 O CM CM VHS» •o Ja OAIlBOd IO CA "c5~ w OAI1V03N o se < tu O CM CM CM s 5 lu I-' 15o H « -16- pos (fumadores y no fumadores) y se hacen muy ostensibles las dife ferencias entre cualquiera de estos grupos con el grupo testigo. Por último la Tabla 3-i, presenta los resultados de esta muestra al disponer los grupos según el tiempo de exposición. No siendo las diferencias entre el segundo y el tercer grupo estadísticamente significativas; y siendo naturalmente significativas las diferencias entre cualquier grupo y el grupo control. CONCLUSIONES GENERALES DEL ANÁLISIS DE LAS DOS MUESTRAS : 1) Pese a que en la muestra testigo elegida había una gran incidencia de alteraciones respiratorias por la frecuencia del asma bronquial, es clara la diferencia entre esta muestra testigo y cualquiera de las poblaciones examinadas. Estas diferencias se acusan más en el diagnóstico integrado y en la radiografia que en la exploración funcional y clínica. 2) El grupo de obreros que trabaja en azucareras se encuentra más afectado que el grupo textil y el inespecífico siendo muy notable la presencia de Neumoconiosis específicas en los dos prjL meros (37? y 19?) y de alteraciones inespecíficas en el tercero (67?). Este grupo lo formaron obreros de la industria del tabaco, artículo de pulpa de madera y papel de fabricación de alimentos. 3) La patología debida al clima laboral es más importante que la del cigarrillo, al encontrarse dañado casi por igual el grupo de fumadores y el de no fumadores. Ya vimos en el Volumen I que en relación con el asbesto se incrementó la patología muy especialmente al sumar tiempo de exposición y hábito de fumar. Las estadísticas muestran mayor significación cuando se incluyen en el grupo de los no fumadores a los fumadores del grado uno. 151 í) Las alteraciones cauaadas por polvo organico son a diferencias de los inorgánicos bastante independientes del tiempo de expos¿ ción. ANÁLISIS ESTADÍSTICOS DE LOS RESULTADOS DEL PROGRAMA DE INVESTIGACIÓN MEDICA EN LA MUESTRA DE TRABAJADORES CON RIESGO DE ASBESTOSIS INTRODUCION: El Volumen I contiene los detalles de la metodología,las características de los grupos estudiados y los resultados individua^ les para cada grupo de los exámenes clínico, radiológico y funciona les del pulmón. Las páginas siguientes contienen el análisis estadístico de toda la muestra en conjunto. Para este estudio de asbestosis recordemos que fue sele£ clonada de un total de siete empresas con 1.500 trabajadores que utilizan asbesto como materia prima para la fabricación de bandas de frenos y cloches como materiales de fricción, baldosas fibro-plásti cas con asociación de asbesto y polivinil, materiales de fibro-ce — mento para la industria de la construcción y, finalmente, materiales refractarios e hilados para ropas de protección contra incendio, cintas, mecates, etc. Se estudiaron un total de 253 obreros que dentro de un total de 1.500 fueron escogidos al azar dentro del grupo de exposición media de cada centro de trabajo. Para ello fue dividido el total de tiempo de exposición, es decir desde el comienzo del funcionamiento de la fábrica hasta el momento del estudio, en cuatro partes iguales y de las dos partes medias (que representa el 50Í del tiempo de exposición) se eligieron al azar los integrantes de la muestra. Ver Tabla 2. Los 253 obreros estudiados fueron clasificados de acuerdo con dos criterios, primero presencia o no de hábito de fumar, 152 segundo tiempo de exposición. No se hizo la selección por puestos de riesgos debido a la uniformidad ambiental de las plantas estudiadas lo cual quedó demostrado por las determinaciones del polvo en suspensión y fibras de asbesto por encima de los niveles permisibles en todos los puestos de trabajo y segundo por la rotación intensa de los trabajadores dentro de las plantas. En cuanto al primer criterio de clasificación la muestra presentó un 80Í (202 casos) de no fumadores y un 20Í (53 casos) de fumadores. Fueron considerados como no fumadores tanto los no fumadores propiamente dichos como los que fumaban menos de 10 cigarrillos al día por períodos cortos de tiempo y como fumadores los que fuman más de 10 cigarrillos al día. Para la clasificación con arreglo al segundo criterio (tiempo de exposición) se han considerado tres grupos: a) Grupo Cero: Formado por aquellos trabajadores que llevan menos de un año en la empresa. Este grupo se ha adoptado como grupo control. b) Grupo Uno : Formado por aquéllos trabajadores que llevan entre uno y diez año en la empresa. c) Grupo Dos : Formado por aquellos trabajadores que llevan más de diez años en la empresa. La distinta proporción de fumadores en estos tres grupos fue del 13.5íí 22? y 20,6%. Desde el punto de vista médico el estudio realizado i n cluye: anamnesis e interrogatorio con especial atención a las enfer_ medades respiratorias; segundo, conocimiento clínico del aparato respiratorio; tercero, pruebas funcionales respiratorias; cuarto, radiología del tórax. 155 z S M z OAI1V03N s H311V NIS 9 XVBOl + TITO (0 « 1 « 0 S 1W NIS zi * 13WOSV3 NOisiuia Il - z *"" Il - z" soixiw 183H 'iSSO 8 II z H V 0 0 '8 n 8 OAIllSOd OAI1V03N S » z (D M S s « n 8 CD .8 s S Î5 e O 8 n z e a « CI "<0 zII» z" 8 8 is z™ Il » z" n z S IP <D II z M II a «D MI fi UVI»inj 3a OilBVH co •» II Z CD M O © 8 CM 2 S 8 H z »S z- a Cl 3 II Z s a zs z * - 1 S ¿6 fi 1 5 M S il z m o * 8 n z 8 W 9 Il z 3 N S 8 z ß o 1 1 3 ï 3 II z a m NO FUMADORES I II z II Z 1 S H0USO9 M N = 51 XVH01 3 il 1 M N = 20 E r- N —53 GRUPO O TE. < 1 AÑO Ï FUMADORES 'dSOS N = 202 RADIOLOGIA EXPL CUNICA ALT. FUNCIONALES OAIllSOd o r- N 8 II z NOIOISOdXS 3 0 OdW3U 154 8 î! 8 S fl 3 0 < z ü ui 2 s s C0 «0 8 n z « N = 54 GRUPO II T.E. > 10 AROS * SOHIO • «ovio * OAIXICM 5 £ ii 1 ito« z EXPL. CLINICA OAUVaiM n ui .j « S u z N O Z p "l 'M 0 '«HIV Mil toxxm • • m • O i 1810 « ci £ z 0 O •o • • o z tfiot ID 4 OAixmotf 5 OAIXVMN •0 o N II Z 5 n z 155 n *ip 30 1 r » • * N = 202 NO FUMADORES f) ñ & 1* o o o w • r 10 M M » M 11 is -xti« « S ;8 * i S £ -1 • •> 10 •o AMOtï» NOItKilO « ea « * • «I o M XI »01 •» m • -«1X1« NIC X»«OX • -1 'M 0 • ••> • • 10 A M « • • z 10 FUÑADORES 4 UVNnj 0XI8VH RESULTADOS: Resultados obtenidos para los grupos de no fumadores se muestran en la Tabla 2.1. Es de señalar que tanto en las pruebas funcionales respiratorias como en la radiología de tórax, por fiif¿ cultades inherentes a todo estudio de este tipo, no se realizó a todos como sería de desear todas las pruebas; este hecho explica que únicamente se dispongan de 155 diagnósticos en los del grupo de no fumadores y 40 en el grupo de fumadores. Para la comparación estadística entre ambos grupos se han considerado: a) Diagnósticos totales b) Alteraciones funcionales c) Diagnósticos neumonológicos más específicos d) Alteraciones clínicas e) Alteraciones radiológicas. Se reunieron en un mismo grupo los diagnósticos de as-bestosis y sospechosos de asbestosis que indudablemente represen-tan estadios precoces de la enfermedad. La significación estadística de las diferencias encan— tradas entre estos dos grupos se muestran en la Tabla 2.2. En la Tabla 2.1, se muestran los datos obtenidos en los tres grupos considerados al clasificar la muestra según el tiempo de exposición. Por último en la Tabla 2.2, se analizan las significaci^ nes estadísticas obtenidas entre los diferentes grupos. CONCLUSIONES: 1) La inspección de las tablas 2.1 y 2.2, nos demuestran cómo el hábito de fumar perjudica extraordinariamente a la salud del trabajador independientemente de las condiciones insalubres que pueda tener el puesto de trabajo y que son indudables en el caso de la muestra estudiada. 156 157 2) En cuanto a la patología específicamente laboral la inspección de las tablas 2.1 y 2.2, nos demuestra ese hecho ya señalado de un incremento claro de la patología según aumenta el tiempo de exposición. 3) Utilizando los valores numéricos obtenidos en las pruebas funcionales para capacidad vital forzada, índice de Tiffe ñau, flujos expiratorios máximos, volumen residual y co cíente volumen residual a capacidad total, expresado en porcentajes respecto al valor teórico para cada obrero, así como los valores obtenidos para las presiones parciales de oxígeno y anhídrido carbónico e índice de difusión, se realizaron estudios de correlación comparándolos con el tiempo de exposición intentando encontrar tiempo de expos i. ción crítica pero sin resultado positivo. A) Se compararon los resultados obtenidos en el estudio anterior con una muestra testigo de 135 personas alejadas del medio industrial elegidas al azar con una composición siini lar en cuanto al porcentaje de fumadores y promedio de edad. El estudio comparativo entre esta muestra y el Grupo Cero (trabajadores con menos de un año de exposición) no dio diferencias estadísticas significativas. 158 BIBLIOGRAFIA 1 Memoria V Congreso Venezolano de Salud Pública. Octubre de 1976. Caracas, Parque Central. 9-16 .2 Extracto de una.Encuesta Preliminar para determinar las Condiciones de Trabajo en la Industria de Venezuela. Ing* Erich Schmith Smith y Sr. Carlos Ruiz Quintana. 19 - 25 de Noviembre de 1956. 3 Informe al Gobierno de Venezuela de la Misión Multidisciplinaria del PIACT, que visito al país del 8 - 2 9 Noviembre de 1976. PIACT/MDT/1. Oficina Internacional del Trabajo. Ginebra. Abril 1977. 4 I Congreso de Ciencia y Tecnología. 5 Memoria VI Congreso de Tisiologia y Neumonología. Ciudad Bolívar. Junio - Julio 1969. Revista de Tisiologia y Neumonología. Volumen 11 Nos. 1 y 2. Junio Diciembre 1969. Instituto Nacional de Tuberculosis y Enfermedades Pulmonares. El Algodonal - Caracas - Venezuela. Caracas - Parque Central. 1975. 6 Memoria de la IV Reunión de la Comisión Nacional de Fisiopatologia Cardiopulmonar Celebrada en Ciudad Bolívar. 4 - 5 Diciembre de 1970. Instituto Nncional de Tuberei! loéis y Enfermedades Pulmonares. Publicacions "Fisiopatologia Cardiopulmonar. Fl Algodonal - Caracas - Septiembre de 1971. 7 Gaceta Oficial de la República de Venezuela. Año C H I - Mes VII. Caracas: Junio 3 de Mayo de 1976. N" 30.972. Decreto N"1543 del 27 de Abril de 1976. 8 Informe Especial presentado al Ministerio' de Sanidad y Asistencia Social y Ministerio del Trabajo. Actividades Comité Nacional de Neumoconiosis desde 1968 hasta 1976. 9 Archivo Comité Nacional de Neumoconiosis. Informe del Asesor Técnico de la Dele gación Gubernamental a la 61a. Reunión Internacional del Trabajo. Ginebra - Junio 1977. 10 Actas Provisionales N°22 de Vigésima Cuarta Sesión. Viernes 17 de Junio de/1977. (Pueden consultarse Actas Provisionales 17 A y 17 B precedentes)' 11 Anteproyecto Ley Orgánica Sobre Condiciones y Medio Ambiente de Trabajo. rio del Trabajo. 1978. 12 Encuesta Nacional. Volumen I. Ministerio del Trabajo. Comité Nacional de Neun» coniosis. Decreto Presidencial 1543. Tipografía Mauro. Marzo 1978. 13 Memoria en preparación de la V Conferencia Internacional de Neumoconiosis. vo Comité Nacional de Neumoconiosis). 14 Epidemiología. Segunda Edición. Dr. Anibal Osuna. Fondo Editorial de la Escuela de Salud Pública. Universidad Central de Venezuela y Ministerio de Sanidad y Asie tencia Social. Caracas 1973. 159 Ministe (Archi 15 Evaluación de Programas de Higiene del Medio. Organización Mundial de la Salud. Series de Informes Técnicos N°S28. Ginebra 1973. 16 Employment Medical Advisory Service. Guidance. 1973. 17 Anuario de Estadísticas del Trabajo 1977. nisterio del Trabajo. 18 Estadística para las Ciencias Administrativas. Copyright. 194 by Me Graw Hill INC. Usa. 19 Metodología de Investigación. Tercera Edición. nezuela. Hijos de Ramiro Paz. S.R.L. 1977. Chieg Employment Medical Aviser'«. Notes of 160 Dirección de Estadística Laboral. Mi- Segunda Edición. Lincoln L. Chao Carlos A. Sabino. Impreso en Ve F/9 LA SILICOSE AU BRESIL - ETUDE EPIDEMIOLOGICHE FONDEE SUR UNE ANALYSE DES HOSPITALISATIONS DA'NS LES ETABLISSEMENTS POUR TUBERCULEUX R. Mendes Brésil On sait que la tuberculose pulmonaire complique souvent l'évolution dû la silicose, donnant lieu à une silicotuberculoee. Dans le dessein d'élargir les connaissances actuelles sur l'épidémilogie de la silicose au Brésil, l'auteur a anlysé de près les anamneses de 3.'4^0 naïades adultes du sexe masculin hospitalisés pour tuberculoso dans 2.7 établissements spécialisés du sud-est du Brésil. Les recherches effectuées sur des dossiers professionnels complets ont révêlé l'existence de 327 cas "suspects" de silicotuberculose (9i5 pour cent des enquêtes). Trois médecins possédant une grande expérience des pneumoconioses (doux pneunalogistes et un radiologiste) ont étudié les clichés thoraciques de ces malades sans connaître leur dossier et san6 se consulter; dans 119 des cas (3,5 pour cent), ils ont constaté dos signes positifs do pneumoconioses ou des images suspectes. En appliquant ce taux de silicotuberculose à l'ensemble des admissions d'adultes du sexe masculin enregistrées en 1977 et compte tenu de la fréqr.onco de la fréquence de la tuberculose parmi les silicotiques - elle est de 3,3 pour cent au Brésil -, on peut estimer a 30.000 environ le nombre des silicotiques au Brésil. Ils ont présenté certaines des caractéristiques épidêniologiqueR dos 119 cas décèles: âge, lieu de naissance, lieu d'exposition a la silice, activités professionnelles, durée d'exposition. En concluant, l'auteur relève l'importance de la silicose en tant que problème de santé publique, et voyant une maladie professionnelle à laquelle il convient qeu les organismes spécialisés du Brésil attachent une importance prioritaire. 161 n/3 I i\ STITronr nn,|C; II»T K-TMF n~ SOOTM-FI upr) OF Tllf'TSTF r.rPRNFfl - A. r.unrMFTl - ft. RFM KMFnFR _ ST! VTA HAHOR I.. Fl. Nr*Kl Institut Hfi Pneumn-Phtisinlnnie de l'Ariana, Tunisie. CRB dernières anníss, nnus avons nhsen/i un nombre important He silicose et si 1 icn-tuh.erculose a un stade avancé nrovenant d'une mine de spath-fluor. Par conséquent, nous avons decidí d'entreorendre une enquête radio-clinique succossive afin d'étudier et mieux connaître 1'étinnathooénie de ces formes nraves de silicose et silico-tuberculose. La fluorine mi spath-fluor (Ca F«) est un minerai utilisé dans une l a m e mesure dans l'industrie et notamment pour la production de l'acide fluorhydrique. Le contenu en silice libre (SiO_) de la roche mere varie de.15 a 30 " suivant les qisements. Les conditions de travail sont encore rudimentaires: sans mécanisation suffisante et sans mesures efficaces de prévention. L'abbatane se fait au marteau-piqueur et a sec. Il n'existe jusqu'à Présent ni forane a l'eau, ni arrosaoe des déblais de roche, ni ventilation mécanique efficace. NATFRIFL FT HETH0DFS : La mine concernée a un effectif rie 600 employés environ. Nous avons effectué deux dépistaoes radioloninues successifs a l'intervalle de deux ans sur des films de 10/10 cm. Tous les suspects ont bénéficié d'une radiooraphie standard. Certains d'ontre eux ont subi des explorations fonctionnelles (snirométrie simple), une na7ométria (un nombre réduit) et pour SS cas, nous avons nratioué trois bacilloscnnies et trois cultures D O U T r " 163 Parallèlement, nous avons entamé das sxpériences sur des animaux da laboratoire avec la poussiere de galeries récoltée de différents endroits. RESULTATS ET COMMENTAIRES : A l'occasion du premier dépistage (en 1976), nous avons examiné 541 ouvriers, soit 90 % dea employas. Il est a souligner que 70 % dos ouvriers examinés ont l'âge antre 21 et 40 ans. Globalement le résultat radioloqique est le suivant: (Suite) Tableau No. 1 164 u e c to D O) co œ •»H 'H CD •J o D tr «0 *H e -o o h c <c o o o. T I E « l ü CC •o 0) !« 0) i-* o •w m -* ^H c O o 3 e. o CM E o «O 3 en a o en <-' eí (D •• *-4 O• ¡ c CM ! va to •X a c o z 3 CD O #H X) CO 1- •H m «<D _l O •o 1 o • o. >• fr- ! S) œ <_> O) •D O li J3 E £ *" 165 o o (0 -p c o u (* D O a 50/íi dB3 sujets ayant une imane thoracique normale nrésentent des calcifications hilaires, témoin d'une ancienne primo-infection radioloqlquemsnt patente et 3,6 % des lésions séquellaires parenchymateuse3 ou pleurales. Ces constatations reflètent une certaine qravité do l'endémie tuhnrculRiise du milieu ambiant. L'emphysnma sans autres sinnes de silicose représente 3,1 "*i. Etant donné le bas aoe des sujets atteints, il nous semble otre au premier lieu la conséquence de l'empoussiéraoe professionnel. Par contre, les anomalies de la si- louette cardiaque ont été rencontrées dans la tranche d'ane allant de 50 à 60 ans. Finalement, 72 cas ont été retenus (13,3 %). Ils ont tous bénéficié d'une radiographie standard; 55 d'entre eux de trois bacilloscopies et 3 cultures pour B.K.; 40 d'une spirometrie simple et 8 d'une gazomôtrie. A la lumiere de ces examens, ils se répartissent ainsi: Tableau No.2: 72 CAS SUSPECTS DES 541 EXÁNIMES SILIC0SILICOSE SILICOSE TURERCULOSE SUSPECTEE 39 8,655 8 ^ 12 TUBERCULOSE STABILISEE 10 2,2 % 1,B % AUTRES TOTAL 3 72 0,5 % 13,35« !>''' ( Il (' ' t Les cas do silicose et rie silicn-tuherculose sont analysé par raoport a l'ane, a l'ancienneté au poste de travail et a la situation familiale. 166 Tableau No. 3 : CAS OF SILICOSE: SELON LES STADES RnnioLcninuEs, AHE, ANCIENHETE ET NOMBRE D'ENFANTS Silicose p Silicose q Silicose A Silicotuberculose 15(31,9 %) à (B,R ?,) R (17 ?5) NOFIRRE OE CAS 2n D (á?,55?) Ane moyen/ans 39 AnciRnneté au travai l/ans 8,2 Nombro d'enfants à leur c h a m e 4,2 39,7 43,2 43,2 10 11,2 10,5 4,5 3,8 4,3 On constate tout d'abord que l'âge de9 mineurs atteints est relativement bas (41 a n s ) . La durée d'exposition au risque est assez courte (10 a n s ) . Le taux de silico-tuberculosB éleva.-Une fois la silicose installée et le mineur restant dans les mêmes conditions de travail, l'évolution de la maladie sera plus rapide. En dehors du terrain silicotique prédisposant le nourcentaqe de silico-tuberculose élevé est beaucoup plus en relation avec l'endémie tuberculeuse de la rénion. Au point de vue ôpidémio- looique, la silico-tuberculose représente 1,4 % du total des mineurs examinés et 17 % des silicotiques. Sur la plan fonctionnel, les résultats de la spirometrie simple sont les suivants: 167 Tableau No. 4: LA SPIROMETRIE DE 40 CAS SYNDROME OBSTRUCTS 25 % SYNDROME RESTRICTIF SYNDROME PlIXTE ' NORMAL 30 % 5 «í 40 % Il nous semble que celles-ci n'apprécie pas suffisamment le degré ráel de la perturbation fonctionnelle respiratoire. La majorité de sujets atteints (60 %) présentent un syndrome mixte (30 %) et restristif (5 %) témoin d'une fibrose d'origine professionnelle chez des sujets relativement jeunes. Par contre, la gazométrie comparée a l'E.f.R. (exploration fonctionnelle respiratoire) nous paraît plus suggestive quoique il s'agit d'un nombre limité des cas. On note une baisse plus ou moins importante de la Pa 02 (soit 7/8 cas) au repos même en regard d'une E.F.R. normale. A l'effort imposé (un équivalent de 40 U) ces sujets présentent une baisse notable de la Pa 02. Malgré le nombre réduit des malades explorés, on constate une Pertubation gazométrique sionificative s'installant déjà dans des formes débutantes. Apres deux ans,un deuxième dépistage intégral a été effectué (480 ouvriers examinés). On note une léoere diminution du nombre de nouveaux 3ilicotique3 (33 cas soit 6,8 %), sans formes oravfis nt une chute appréciable de la filino tuberculose (2 cas oour 33 silicoses soit 6 %). 168 T a b l e a u n° 5 : IA GAZQKETRIE DE 8 CAS AU JìEPOS ET A L'EFFORT (40 ff) • Pa 02 rrn Hg N" COURANT DE MALADES Pa C02 mu Hg • THORAX', Repos '. Repos Effort 52 : Effort 1 27 42 C.V 117 X V.M.M. . . . 119 X V.E.M.S. . 79 X Silicose r 42 44 C.V 101 X V.M.M. ... 32 X V.E.M.S. ... 44 X Silicose A 1 78 1 E.F.R. 1 7Z 2 . • \ 3 8S 82 40 37 C.V V.M.M. .... V.E.M.S. . 76 X S3 X 48 X Silicose B, o 4 7S 77 4b 42 C.V 100 X V.M.M. . . . 39 X V.E.M.S. . 75 X Silicose p, 2 S 72 69 40 6 7 8 \ 7S 70 82 80 90 . 54 36 '. 32, S 43,5 C.V 305 X V.M.M. . . . 57 X Silicose ' V.E.M.S. . .. 63 X '. 37 33,5 '. 46 169 r ' C.V 70 % V.M.M. . . . 46 % ' V.E.M.S. . . 73 X Silicose A ' C.V 80 X [ V.M.M. ... 54 X '^V.E.M.S. . 57 S Silicose A ' C.V V.M.M. . . . V.E.M.S. . Silicose p 102 X 99 X . 83 X Parallèlement, des expiriences sur Hns animaux de laboratoire ont iti effectués ause la nnunsiam rio paierie. Cotte poussiere de fluorine ainsi ricoltie:cootient 9,5 % de silice libre (Sin?). Pn a utilisé des rats d'un noido moyen de 20^0. La poussiere auec ries particules rie moins rie 5 microns de diametro n iti administrée par injections intra-trachiales a dose de oP mn/ml sérum physiolonique-animal. 15 animaux ont iti ainsi emnoussierís et un lot timoin de 10 autres ont repu oar la memo unie 1 ml de sirum physiologique. Tous les animaux ont survaicu a 1'empoussiiraoe. flores trois mois, tous ont été sacrifiis. On constate que: 1) le poids des poumons empoussiéris a aunmenti par rapport au lot timoin; 2) aunmentation sipnificative du poids des nanqlions trachéo-bronchiques traduisant un intense nettoyane par voie lymphatique; 3) 1'hydroxyproline sionificativement aunmentie (intensification du processus de riticulisat.ion et de collaninose) - Tableau 1 A l'examen histolooique, le poumon prisante un important processus inflamatoire a tendance nodulaire ipars et par ailleurs, des amas de cellules desquamatives lymphocytes et macrophages. Pn note aussi (coloration HömfTri) une hyperplasia de9 structures riticulaires et une tendance a la formation des nodules. Les risultats de ces expériences confirment une fois de plus le risque nneumpcnni ot.i que élevé de la poussière de gnathfluor et concordent aven les observations cliniques. 17o FN cnrirLusTPr' : n la suite fin l'étude effectuée, on trouve un taux élevé r)R s.ilirnsn, rnpin'r>mRnt évolutive, entraînant uns invaliditi? profRPsionfiRlle n un haï Ain (41 ans); un noiirc^ntane innulé— tent rin si]ico-tuberculnse (17 'Í). f>s constatations sont rattachées a plusieurs facteurs : 1) les conditions de travail encorn rudimentaires sn- 2) le taux elevi? de silice (Si 02) dans la poussiere de trainnnt un empoussiérane massif; naleries; 3) le panqué de mesures de techniques de prévention; à) le role potentialisateur de la fluorine; B) ânfin, la pravità de l'endémie tuberculeuse dans la rénion. Notre expérience montre qu'une prévention médicale a vu a elle seule renres9er le nombre et les complications de cette redoutable maladie professionnelle. 171 ir ' i/> X o 'al •M o01 E M» l/l 0) — "~ >J 01 _r u I/I 0J D1 0 15 01 -*0) ti d (M O l0 £ oi . ai *i 5î _*si! ci *<y S. i-SJ ff*ü £ JJ, EU -E c ••SB.o ïí a. crji O 01 0 +i - £.&> -0) £ 0 £. °- o S • i >/1 rj a ! m m. oí o» o 00 ö +1 V £• °rM •J "S O. Jl in '5 -S ¡<" iïiT A£ 3 si 9 in o E r tí d { I f» o; w «*** , S . Q-l (NI 1 * ! in or ! In S _û Jl ° 2 in .çr" o o o M "o 3 CT ! a. in o" •sfa o- " i . ^r o3 £ _ro lO 00 o Ö +1 pCi ia o m 0 i. Cft" 'fi ö p<0.01 St. j£ 0910 10.185 lì* m oo o Ö +' m o .|-|J 3 <£ 172 nifi, innre», M: i r 1) RARWtn C. - ROTARU L. - PETRESCU "Recherches experimentales histo-chimiques sur les rmxcopolysacc1vnrid.ee dans la silicose" Archives des Maladies Professionnelles 28,10/11 : 7G7-778 Oct; Nov. 67. 2) '. BARBAD' B.. - FSTRESCU L. "Réaction physiologique de l'appareil respiratoire sous l'influence Poussières chez les malades atteints de silicose" Arch, des Mal. Prof. T. 23 N"4 (S p. 230-239 Avril 62 des 3) BRUCH J. : "Lufthygiene und silikoseforschnng jahresberich,193Z, seile 125. 4) J, ÇBAMPEJ et FOURIER P. "Quatre cas a'ostéopathies par intoxication Ann. «ed. Leg. N" S •*• 1954 pp 1-7. fluorée chronique" 5) CBAMPEX J. "Observations récentes d'Osteoporose fluorée Arch. Kai. Prof. T. 21 - N"6 1966 - 357-361 professionnelle 6) CORNEA G. - EL GHARBI V. - L. EL MEKKI - M. ZBIBA "Le profil clinique et radiologique des moiades silicotiqves à l'Institut de Pneumo-Phtisiologie de l'Ariana " Congrès Maghrébin de Médecine - Mai 1975. hospitalisés 7) CORNEA G. - GHACRFM A. - BEN KHEDER A. - EL MFXXI L. et BOVACHA H. "H propos du dépistage des pneumoconioses dans les mines de Tunisie" ZVèmes Journées Nationales de Médecine du Travail Strasbourg - 10*13. Mai 1978 8) CRETEAUmi Gh - VRSULESCÜ GR -.K. Congr, Nat; IT de Igiena, IEREftTCWC. •* P. DVMITm, 7. PISLARU Bucuresti 1968, P. 188. 9J LVTON et J. CBAMPEX .. "Etude sur les pneumoconioses dans les gisements de Ar de Mal. Prof. - T.12 N" S •* 1951 - pp 506^ 518. spath-fluor" 10) EL MEKKI L; - CORNEA G. - EL GRARBI B. - HAMZA R. - ZBIBA M. - BEN KHEDER A. "La silicose pulmonaire 1971 - 75" Tun. Med. N" 4 juillet en Tunisie à propos de 114 cas observés en 5 ans Août 1976. 11) PESTIAVT ,T.L. - LOVSSAIEF M.L. - SANCHOU M. "Le problème de la Silicose dans une mine de fluorine Tun. Med. Nov.- Dec. 74 p. 337. en Tunisie". 12) POÎ.TCARD et A. COLLET "Recherches expérimentales sur la nocivité (fluorine) ". Arch; Mal. Prof. T. 24 N" 2 - 1953. 173 des poussières de spath-fluor La silicosis en una mina de espato-flúor de Túnez. G. Cornea, A. Ghachem, A. Ben Kheder, S. Gabor y L. El Mekki (Túnez) Hemos llevado a cabo en una mina de espato-flúor en la que trabajan unos 600 obreros dos controles radiológicos sucesivos con un intervalo de dos años. Las condiciones de trabajo son todavía rudimentarias. La presencia de SiO- (sílice) libre en el polvo de las galerías es de 9,5 por ciento. En el primer control (1976), se descubrió que el 8,6 por ciento del personal sufría de silicosis, con formas avanzadas en una cuarta parte de los casos. La asociación con la tuberculosis (silicotuberculosis - B.K. positivo) representaba el 17 por ciento. La edad media de los enfermos era de 40 años, y la duración media de exposición al riesgo, de 10 años. La espirometría simple resulta perturbada en 60 por ciento de los casos. La gasometría efectuada con 8 enfermos muestra una disminusion más o menos importante de la Pa0?, incluso en descanso, pese a una exploración funcional normal. Transcurridos dos años, se ha procedido a un segundo control radiológico integral. Se observa una ligera disminución del número de víctimas de silicosis, sin formas graves y con sólo dos casos de silicotuberculosis. Paralelamente, se empolvó con polvo de las galerías a animales de laboratorio que han sido sacrificados al cabo de tres meses. Se ha comprobado lo siguiente: 1) aumento del peso de los pulmones empolvados en relación con el grupo testigo; 2) aumento apreciable del peso de los ganglios tráqueobronquiales, lo que traduce una intensa limpieza por vía linfática] 3) aumento significativo de la hidroxiprolina (intensificación del proceso de reticulización y de colagenosis). 174 Eh el examen histológico, el pulmón presenta un importante proceso inflamatorio con tendencia nodular dispersa y también aglomeraciones de cédulas descamativas, linfocitos y macrofagos. También se observa (coloración GSraöri) una hlperplasia de las estructuras reticulares y una tendencia a la formación de nodulos. Los resultados de estas experiencias confirman una vez más el elevado riesgo de neumoconiosis que entraña el polvo del espato-flúor y concuerdan con las constataciones clínicas. 175 VARIABILITY IN THE X-RAY DIAGNOSIS OF EARLY SILICOSIS * J. Prenafeta G., G. Leyton M. and R. Sepulveda M. (Chile) In 50 workers exposed to a silicotic hazard a posteroanterior chest radiograph was performed. Everyone of these radiographs was read by 7 experienced physicians. In addition, 4 of them made a second reading of the same films. So, each film was read 11 times. The readers had to conclude on the existence or absence of X-ray signs of silicosis. No unconclusive diagnosis was allowed. Results showed that there was a diagnostic agreement in 72% of the cases, ranging between 50 and 90%. The standard deviation was 9.2%. Only 7 films were informed as negative for silicosis in the 11 readings. On the other hand, there was no film informed as positive for silicosis in the 11 instances. * Papers "in extenso" can be asked to the authors. 177 EXCESS LUNG CANCER RISK IN SILICOTIC CASES* UNDER HOSPITAL CARE - PRELIMINARY REPORT (Summary) K. Chiyotanl, Ken-ichi Saito Rosal Hospital for Silicosis Fujiwara, Tochigi, Japan In the Rosal Hospital for Silicosis, a special hospital for pneumoconiosis in Japan, 15 deaths in patients with silicosis complicated by lung cancer were observed In 1966-77. The average age at death was 64.5 + 9.1. While past surveys showed that the average death age of silicotics as a whole In this hospital was 47.1 + 7.8 In the period 1950-54, becoming older year by year, recent surveys demonstrated that the average death age did not reach the age for cancer death quoted above, even in the period 1971-75. Therefore, the relative risk of lung cancer In sili- cotics was calculated from the data obtained after 1971. This study showed that silicotics had a considerable excess risk of lung cancer. The necessity to shed more light on the relations between silicosis and lung cancer is stressed, though such a relation has been rejected for several years. * Paper "In extenso" to be asked to the authors. 199 Agravación del riesgo de cáncer de pulmón en los enfermos de silicosis internados en hospitales. Informe preliminar K. Chiyotani y Ken-ichi Saito (Japón) En el Hospital Rosai para Silicosis de Japón se observaron 15 defunciones de enfermos de silicosis complicada con cáncer del pulmón entre 1966 y 1977, y el promedio de edad en el momento de la muerte era de 64,5 + 9,1. Si bien las investigaciones anteriores muestran que la edad promedio de muerte por silicosis en enfermos hospitalizados era 47,1 ± 7,8 en el período 1950-1954, y que avanzaba anualmente, los estudios recientes de los autores demuestran que la edad promedio de muerte no alcanza el nivel de los casos de muerte por cáncer mencionados ni siquiera en el período 1971-1975. Trataron, en consecuencia, de calcular el riesgo relativo de cáncer de pulmón en los enfermos de silicosis a partir de los datos obtenidos después de 1971. El presente estudio muestra que el riesgo latente de cáncer de pulmón está muy aumentado en los enfermos de silicosis. Los autores desean subrayar la necesidad de insistir en los problemas que plantea la correlación entre silicosis y cáncer de pulmón a pesar de que se los suele negar y de que su estudio fue abandonado durante varios años. 18o EPIDEMIOLOGICAL SURVEY AND PROGNOSTIC EVALUATION IN SILICOSIS * (Summary) J. Prenafeta G., A. Valenzuela P., G. Leyton, Srta. S. Villagran 0. (Chile) All cases of silicosis detected during the period 19621964 at the Chilean National Health Service were followed up. The most favourable prognosis occurred in the earliest forms of the disease in which the probability of deterioration was 20.4/1,000 year-person and the rate of tuberculisation was 3.5 times that of the general adult population. The prognosis in relation to the variables "stage of the disease at the first diagnosis" and "over exposition" was analysed. The probability of deterioration was analysed in relation to the number of years after detection, and it was concluded that the highest rates of deterioration occurred before the seventh year, after which the probability persisted at a much lower rate. * The paper "in extenso" to be asked to the authors. 181 T N O i c c III. ! III; II S E S S I O N TII «.sai-hard. L'évaluation du risque coniotlque sur les H P U X du travail C.Cornea., ft.Ghachem. , A.Sen Kheder., J.Daghfous., H.Bouacha., L.E1 Rlefckl. La Pneumoconlose dan9 una mine de fer de Tunisie aspect9 radio-clinique et fonctionnel. III. III C.E.Rossiter., J.C.Wagner. flan-Clade minerai fibres: joint Eurèpean medical research project. III. IV 0.F.Goldsmith. , J.r.Gamble., N.Stroup., C.m.Shy. Chronic lung disease In the furniture industry: An epidemiologic study design. III. V Hl.L.H. Flindt. Pulmonary disease due to proteolytic anzymes. III. VI S.W.Rab., Zateoullah Beg and lï.Abu Zafar. Work-Related diseases in Pakistan. III. VII Cornea G., El Ulehki U., El Charbi B., Ben Kheder ft. Silvia G. Une nouvelle Pneumoconiose vegetale 183 Le poumon de Neffa III/l L'EVALUATION DU RISQUE CONIOTIQUE SUR LES LIEUX DU TRAVAIL Dr. B.Barhard Institut d'Hygiène et Santé publique - Bucarest Roumanie. L'extension continuelle des procédés technologiques engendrent des poussières et les limites relatives du rendement des moyens techniques de lutte, l'augmentation progressive du nombre des ouvriers exposés, le caractère invalidant et les conséquences économiques-sociales des maladies dues aux poussières sont les principaux éléments qui justifient 1'approfondissement des relations "cause-effet" et "exposition-réponse. Mais l'établissement de cette relation et surtout sa quantification se heurte encore à de nombreuses difficultés, qui touchent aux deux termes de la relation. Des difficultés d'ordre théorique (scientifique) ont déterminé et entretiennent des difficultés d'ordre méthodologique, concernant l'uniformisation et la standardisation des moyens en vue de l'objectivisation (de la caractérisation) du risque, sur la base des critères de sensibilité, de représentativité et de comparabili té; or ce sont justement ces instruments d'objectivisation qui permettent en dernier ressort la quantification. Comme on l'a remarqué, la sélection des méthodes et des instruments d'objectivisation de l'exposition darra s'adapter au niveau et à l'intensité de l'exposition. Quand la concentration de la poussière est élevée, donc quand le degré d'exposition est élevé lui aussi, le rôle de l'empoussiérage est déterminant, tandis que celui des autres facteurs est négligeable; dans cette 185 symétrie, la concentration des poussières de l'environnement, la teneur en substances biologiquement actives et la durée de l'exposition d'une part et l'importance des lésions pulmonaires décelables à l'examen radiologique d'une autre part se trouvent en bonne correlation (donc il y a une bonne correlation entre le risque et la réponse). Quand les niveaux de l'exposition diminuent, à la suite de l'augmentation du rendement des moyens de lutte contre les poussières, les autres variables (y compris la sensibilité individuelle) gagent une importance toujours plus grande et peuvent dominer la relation; dans ce cas il sera nécessaire de perfectionner les systèmes d'évaluation, tant sous le rapport du stimule (l'agent spécifique), que de la réponse (réactivité) . Mais les difficultés et les exigences se présentent quand on pose le problème de l'adoption du système des concentrations maximales admissibles, par lesquelles il faut assurer la protection de la population exposée su risque. Car les experts se sont posé à juste titre la question: "Est-ce qu'on devra envisager l'établissement de normes exprimées en unités d'exposition (mg, h,m-5) ou en unités de concentration (mg/m-')"? Une réponse acceptée de façon unanime n'a pas été encore donnée et cela souligne de nouveau la difficulté de la quantification du risque. Dans ce contexte, nous nous proposons d'exposer une bilan des connaissances accumulées dans l'approche du risque coniotique; - - 1» facteur ôtiologique - évalué par les caractéristiques quantitatives et qualitatives, considérées de façon dynamique ; 1* facteur exposition - évalué par le nombre des ouvriers exposés au risque et la durée de leur exposition et 186 - le facteur biologique - la rôactivitê de l'individu ou de la collectivité exposée, évaluée par des indicateurs de l'état de santé. Pour ce qui est du au facteur étiologique, le risque coniotique, l'investigation réclame l'acceptation de certains desiderata d'ordre méthodologique (techniques: de mesure - analyse - évaluation). Parmi les desiderata indispensables, mentionnons: la sélection des indicateurs de manière qu'ils soient objectifs, pertinents, représentatifs; la sélection des méthodes et des techniques afin d'objectiviser les indicateurs choisis; l'uniformisation des techniques de prélèvement de mesure et d'analyse; l'adoption d'une méthode d'investigation appropriée au but poursuivi; l'uniformité de l'interprétation de l'information. La première étape consiste dans l'étude technique et du procédé technologique depuis la matière première jusqu'au produit fini, dans laquelle on observera les opérations du cycle de travail, la nature et le mode de génération des poussières, les moments où les dégagements sont le plus importants, les conditions dans lesquelles ont lieu ces dégagements, le degré de mécanisations et le rythme de la production, l'existence et l'efficacité des moyens techniques de lutte contre la poussière et le nombre d'ouvriers exposés. Le chronogramme professionnel d'un nombre représentatif de lieux de travail empoussiérés complète l'information dans cette première étape. Sur cette base on établit lee lieux de travail à investiguer ainsi que la fréquence des mesures et l'on élabore un programme pour les investigations de l'étape ultérieure. Quelques indices d'ordre général sont recommandés en fonction des niveaux d'empoussiérage connus et du degré de nocivité des poussières: mesures continues sur la durée d'un cycle de 187 travail, plusieurs jours de la semaine (de façon différenciée dans l'industrie extractive, l'industrie de surface,.l'industrie textile etc.) et pendant au moins deux étapes annuelles selon le niveau de la production et de la saison). L'étape de mesure-évaluation tient compte de la caractérisation quantitative et qualitative des paramètres physiques aussi bien que chimiques de la poussière de la zone de travail en fonction de l'action biologique, de la durée de l'action sur les sujets exposés et des caractéristiques du travail (régime de travail, effort, mécanisation etc). La concentration de masse de la poussière en suspension (niveau de l'empoussiérage) est mesurée sur le lieu de travail dans la zone respiratoire de l'ouvrier, par des déterminations continues) (sur la durée d'un poste), l'évaluation se faisant en deux degrés - poussière intégrale et fraction respirable. Des progrès considérables ont été enregistrés en matière d'équipement de prélèvement ou de mesure (apports de la 5ème génération), mais aucune norme internationale n'a été adoptée. L'analyse de la poussière concerne la détermination éléments constitutifs et surtout des éléments biologiquement actifs de la poussière de suspension de la fraction respiratoire. L'étape d'interprétation des résultats consiste dans la synthèse de l'information recueillie, à des intervalles de temps déterminés, et les conclusions se rapportent au système des valeurs de concentrations maximales admissibles. Dans cet ordre d'idées on souligne l'importance de l'élaboration d'un système d'informations unitaire centralisé pour le stockage des données et leur traitement statistique-mathématique par des techniques modernes. Ce système comprendra des informations tant sur le niveau de l'exposition que sur sa durée. 188 La mise en valeur vise un seul but: l'efficacité de l'ensemble des mesures techniques et organisationnelles de lutte entre la poussière industrielle, efficacité exprimée en termes quantitatifs sans dépasser lee concentrations maximales admissibles. Une seconde méthode d'évaluation du risque coniotique consiste dans les enquêtes êpidômiologiques. Cette méthode doit être considérée en étroite liaison avec la première, autant par rapport à leur objectif commun, que par rapport au fait que les investigations du milieu offrent un critère pour la sélection de la population - l'intensité de l'exposition au risque. Les études épidémiologiques sur les pneumoconioses ont deux objectifs: - quantifier le niveau de la morbidité dans les populations industrielles exposées à diverses variétés de poussières. De telles études visent des buts immédiates (dépistage des sujets qui peuvent bénéficier de l'assistance médicale spécialisée), qu'informationnels et prognosi iquee, étant donné qu'elles constituent étant donni qu'elles constituent les principaux moyens d'obtenir les données nécessaires a l'évaluation du problème pour les organismes des décisions médicaux. - mettre en évidence les principaux facteurs de risque et leur variation sous l'influence des mesures de prévention, qui se traduit dans une modification du niveau de la morbidité, indiquant l'efficacité sociale et économique des programmes médicaux et techniques. Certains des problèmes posés par ces études sont communs è toutes les études épidémiologiques, tandis que d'autres sont particuliers et liés aux traits spécifiques de ces maladies. 189 Contrairement à la plupart des maladies chroniques, dans le cas des pneumoconioses on connaît autant le facteur êtiologlque - la poussière contenant du SiO- libre, que les principaux mécanismes pathogêniques. Pourtant, la correlation entre l'exposition et la quantité de modifications pulmonaires attribuées à celle-ci, est réduite ou modifiée par l'intervention de nombreux facteurs secondaires dans la pathogénie de la maladie, et par les changements répétés qui sont intervenus dans les techniques de prélèvement. Les mesure6 et techniques de lutte contre les poussières ont mené à des changements d'ordre qualitatif (physique et chimique) et quantitatif des particules de poussière et le degré d'empoussiérage s'est réduit. La réduction concerne surtout les particules ayant un contenu réduit en silice libre, et l'on a constaté une modification de la dispersion des aérosols de poussière, soit une augmentation de 60 à 90 % de la proportion des particules de petites dimensions (moins de 5 pm). On rencontre une situation similaire quand on utilise les données concernant les modifications radiologiques observées dans les poumons, car les techniques de dépistage et les critères de diagnostic ont subi des changements importants. Cet état de choses pose des problèmes pour tes enquêtes rétrospectives et facilite en revanche les études transversales. Il's'ensuit que le meilleur moyen d'évaluation de l'exposition individuelle dont nous disposions est le stage professionnel dans les conditions de risque. C'est évidemment, une évaluation qui manque de finesse, mais pour le moment c'est l'unique indicateur quantitatif et individuel à l'aide duquel on peut mettre en évidence l'existence d'une relation entre l'exposition et la maladi' 19o Lors de l'élaboration de la méthodologie,un autre problème qui se pose est celui de la sélection des lieux de travail. Dans certaines industries, l'extraction des minerais par exemple, on ne peut pratiquement pas parler de lieux stables. L'évaluation du degré d'empoussiérage est rendue difficile aussi par l'utilisation dans la même mine de plusieurs techniques d'extraction en associations variées et inconstantes, surtout lorsqu'on ne pratique qu'un nombre limité de prélèvements. La population n'est pas homogène ni du point de vue biologique, ni du point de vue social ni en ce qui concerne le degré d'exposition au risque des individus. Les niveaux moyens de l'exposition varient beaucoup par rapport à la technologie et aux moyens de lutte contre la poussière. L'exposition est donc difficile à évaluer dans des termes quantitatifs. Il est difficile aussi de recueillir des données sur l'exposition à d'autres facteurs de risque tels que l'usage du tabac ou les maladies respiratoires antérieures. Les informations sont obtenues par •interview",la personne interrogée doit pouvoir et désirer comprendre les questions, reconnaître les symptômes et donner des réponses exactes; l'ôpidêmiologie ne peut pas contrôler ses aspects, et les sujets diffèrent par leurs performances. La nature des phénomènes étudiés (souvent les maladies respiratoires sont courtes et ne s'accompagnent pas de grandes souffrances ou d'inconvénients matériels pour le malade) et la motivation souvent insuffisante (le sujet n'est pas convaincu de l'utilité des informations dans la même mesure que les enquêteurs) expliquent l'imprécision assez grande des réponses. Voyons maintenant quelques problèmes méthodologiques spéciaux liés à l'étude épidêmiologique des maladies provoquées par certaines poussières. 191 La penumoconioee dee mineurs du charbon (PNC) est une maladie spécifique qui fait partie des pneumoconioses. Le caractère spécifique est donné par l'étiopathogénie et par le niveau des taux de morbidité • Les enquêtes épidêmiologiques sur la PMC ont des caractérisques particuliers et impliquent l'élaboration d'une méthodologie d'étude spécifique. En Roumanie, l'intérêt pour la PMC s'explique par l'importance de l'industrie charbonnière qui emploie Un grand nombre de personnes et par la tendance à accroître eri permanence la sécurité des travailleurs pendant toute leur activité professionnelle . Une étude êpidêmiologique sur la PMC a été effectuée en vue de: - donner une description des conditions actuelles d'exposition des travailleurs, en d'autres termes d'établir quels sont les.poussières et les niveaux moyens d'empoussiérage auquels se trouvent exposés les mineurs de l'industrie du charbon; - évaluer la fréquence des cas de maladie et de modifications radiologiques pulmonaires qui peuvent être attribués à l'exposition aux poussières et identifier les principaux facteurs de risque. On a conduit une enquête transversale qui offre une image générale des effets des facteurs de risque au niveau de la population. Les hypothèses suivantes ont été testées: - peut-on mettre en évidence la correlation entre l'exposition aux poussières et la morbidité respiratoire en utilisant le stage professionnel pour estimer l'exposition ? - l'âge est-il un déterminant biologique de la susceptibilité à la maladie (PMC)? 192 L'étude a commença par una analyse des conditions existant dans les mines de la région afin de sélectionner l'unité qui, par le nombre d'employés, la technologie utilisée et le niveau moyen de l'empoussiérage, était représentative pour toute la région. La population de mineurs sélectionnée pour l'étude a été recensée et l'on a enregistré les caractéristiques biologiques (âge) et professionnelles (stage professionnel), les habitudes liés à l'usage du tabac et les maladies respiratoires passées de chaque travailleur. On a effectué le dépistage de la pneumoconlose par une méthodologie normalisée comprenant: une examination radiologique (radiographie pulmonaire), l'étude de la ventilation pulmonaire (capacité vitale, VEMS, index de perméabilité bronchique) suivies d'un examen clinique et de la recherche des symptômes respiratoires. La réponse des poumons il l'exposition a des poussières variant en quantités et en qualité a été mesurée par la quantité totale de modifications radiologiques constatées. La plupart des mineurs (90 %) ont présenté des modifications pulmonaires minimes et 10 % ont présenté des modifications importantes, ce qui confirme les données des études expérimentales sur l'aggressivité des poussières. L'ftge biologique et le stage professionnel ont une influence déterminante sur le niveau de la morbidité par PMC. Dans le cas de l'amiante, les études épidémiologlques ont pour but d'identifier les.effets pathologiques de l'exposition sur l'état de santé de la population et de vérifier l'hypothèse sur la correlation entre le risque de maladie et l'influence de la poussière. 193 Les enquêtes êpidêmiologiques diffèrent des autres études par le fait qu'elles concernent l'ensemble de la population car non seulement l'exposition professionnelle mais aussi l'exposition dans l'environnement général peuvent être suivies des effets pathologiques. Les effets possibles sont les suivants: l'asbestose, associée ou non à des calcifications pleurales liées surtout à l'exposition professionnelle, le cancer bronchique et le mêsothêliome pleural dont l'incidence a été associée surtout à l'exposition au crocidolite, môme dans le cas de contacts mineurs et éloignés. Les principaux problèmes liés à-la réalisation de ces études sont: l'identification et l'évaluation de l'exposition, la durée, le niveau et la nature du matériel utilisé ayant une très grande importance pour la nature des effets ultérieurs. L'étude statistique de la relation entre l'exposition et la maladie (surtout le mêsothêliome) est modifiée par une série de facteurs parmi lesquels on peut citer: les doutes liées au diagnostic môme, les difficultés à reconstituer l'exposition et l'intervalle très long entre l'interruption de l'exposition et l'apparition de la maladie, période durant laquelle le sujet peut changer de profession et de résidence. Dans beaucoup de cas, l'identification des tumeurs qu'on peut attribuer à l'effet de l'amiante est difficile parce que les malades ont été exposés à d'autres agents nocifs, surtout le tabac et la pollution atmosphérique, mais on peut admettre que le risque est beaucoup plus élevé chez les fumeurs qui travaillent dans des milieux pollués à l'amiante. 194 On peut conclure qu'à présent les enquêtes êpidômiologlques et surtout les enquêtes rétrospectives portant sur les cas de maladie dépistés et admis dans les hôpitaux ou sur les cas signalés dans lee zones polluées, peuvent fournir certaines conclusions sur la relation entre l'exposition à l'amiante et la maladie, de même que sur les facteurs de risque qui peuvent influer d'une manière caractéristique sur les taux de morbidité. 195 Evaluación del riesgo de neumoconlosls en los lugares de trabajo. Informe preliminar B. Barhad (Rumania) Para el especialista en medicina del trabajo, el riesgo de neumoconlosls comprende el conjunto de peligros para la salud que se manifiestan en forma de cuadros clínicos específicos provocados por la exposición profesional al polvo« La evaluación de ese riesgo puede llevarse a cabo de dos maneras i vigilando la exposición al polvo en el lugar de trabajo, o mediante un examen médico sistemático para detectar las enfermedades que puedan imputarse a dicha exposición, Los criterios de evaluación de la intensidad del riesgo de neumoconlosls se presentan por medio de la vigilancia de los lugares de trabajo (identificación de las fuentes de emisión, vigilancia de la presencia de otros riesgos, estudio dinámico del nivel y de la composición del polvo^en suspensión en la atmósfera, evaluación de la ventilación pulmonar externa durante el trabajo, etc.). A fin de asegurar la comparabllidad de los resultados es preciso optar por metodologías y técnicas de análisis uniformizadas. El estudio de los efectos en la población de la exposición conocida desde el punto de vista cualitativo y cuantitativo constituye un medio de evaluación de la intensidad del riesgo de neumoconiosis, y al mismo tiempo ofrece la posibilidad de verificar los conocimientos adquiridos acerca de la agresividad del polvo por medio de la observación en los lugares de trabajo y de los estudios experimentales realizados en laboratorio. Las encuestas epidemiológicas ofrecen Informaciones sobre las relaciones existentes entre los efectos de la exposición profesional y los siguientes parámetros i agresividad del polvo i concentración de polvo en la atmósfera del lugar de trabajo, y duración de la permanencia profesional en ese medio. 196 Merced a esos estudios es posible Identificar la Influencia de ciertos factores de riesgo (consumo de tabaco, endemia tuberculosa, residencia, etc.) que contribuyen a crear una "susceptibilidad Individual a la enfermedad" específica, lo cual explica las diferencias que pueden registrarse entre las tasas de morbilidad observadas en las poblaciones estudiadas y las previstas de acuerdo con estudios anteriores. En la práctica se utilizan simultáneamente esos dos medios para evaluar el riesgo de neumoconiosis. Los resultados del estudio experimental "In vivo" e "in vitro" del polvo de los lugares de trabajo aportan una valiosísima contribución en la labor de investigación de los riesgos. Por último, se examina la necesidad de elaborar metodologías específicas de evaluación, adaptadas al estudio de los riesgos que engendra la exposición a ciertos tipos de polvo, como, por ejemplo, el polvo de mina y el amianto. 197 III/2 i. A PMCurincoNin^r DANS UNE PI I NE nr FER OE T U N I S I E nsprr-rs R(\nTn-CLTMi'-iir FT FUMCTTP^NEL n. rnrìMF/i - n.nnnnHEH - n. PEN KHEDER - .n.riAGHFDUS ii. nni.inrHA - i . EL PIEKKI Institut de Pneumn-Phtisiloaie de l'Ariane Tunisie. Notre étude norte sur les données d'un depistane rarii.nloninue denn une mine de Fe. Le minerai exploité est soit do l'hématite fFpn ) , soit la siriérorite (FeCP,). L'exploi- tation du minerai se fait 9 0 ^ en profondeur et 1OrS a ciel ouvert. Le taux de Si n _ libre dans le minerai no dépasse pas y~'< et dans la roche accomnaonante 7 a 8fî. Dans l'ensemble, les conditions de travail sont satisfaisantes nar rao- nnrt aux autres mines. Plais une amélioration de la ventilation et rie la mécanisation du travail sst souhaitable. riATERIEL ET METHODES: Lé depistane radioloninue concerne 1240 ouvriers, snit plus de "p1"? des employés. Une premiere lecture des films IP/IP cm a retenu 162 sujets suspects. Chacun a bé- néficié d'un cliché standard, d'un examen clinique complet aipsi que d'une ennuete professionnelle portant sur lo poste de travail et la durée d'exposition au risaun. Uinot-cinq malades ont été hospitalisés Dour des explorations fonctionnelles plus poussées. Le microclimat minier ainsi que la cnniométrie ne font nas partie de nntrn trnvn.il. 199 PROFIL _RaninLnnini)!:; a - L'analyse'radioloçique des 162 cas retsnus (soit 13,25? d'ouvriers examinés) montre 1,2% de (pneumoconiose confirmée 4,5^5 de cas suspects de pneumoconiose, l,lîî de tuberculose eéquellaire et 0,08 % de tuberculose cavitaire. Tableau 1 Lésions Nombre de cas PNEUMOCONIOSE CONFIRMEE 90 7,2 PNEUMOCONIOSE SUSPECTEE 57 4,5 TUBERCULOSE SEQUELLAIRE 14 1,1 1 TUBERCULOSE CAVITAIRE 0,08 . TOTAL ... ! 162 L'asoect radiolorique prédominant dans les pneumoconioses confirmées est celui d'image en tete d'épinole, plus ou moins denses, de répartition homogene, sans formes tumorales ni association avec la tuberculose. Dans l'ensemble domine le stade ponctiforme. 2oo T a b l e a u "> STAOF Rnrnninni^nr '''ombre fie Cas Pnurcentane n SS (in,l n 30 33,3 r 5 5,5 b- DONNEES CL IN ICQ-PROFESSIONNELLES : - L'acie moyen des malades e s t de 4 5 , 7 ans - L'ancienneté au poste de travail est de 18,3 ans - La durée de travail au marteau piqueur est de 12,2 ans - Le taux des fumeurs est de 86,5$ Priseurs de NEFFA (poudre de tabac a priser) : 13,9 %. Certains d'entre eux prisent et fument en même temps. La Symptomatologie clinique chez nos malades est marquée dans la majorité des cas par une dyspnée a l'effort (70 3 ) , une toux productive (64 %), des arthraloies(54 <) et des hémontvsies de oetite imoortance (14,4 Tí) sans explication nette. 2o1 Concernant 90 cas de pneumoconiose et 57 oas suspects de pneumoconiose Tableau 3 SYMPTOME CLINIQUES ! PNEUMOCONIOSE CONFIRMEE PNEUriOCONIOSE SUSPECTEE Dyspnée 70 4 3 , 7 •& Toux 64,6 % 43,7 % ¡ ' Expectoration 64,4 r> ; 30 % 20 % 28 % 20 ;0 j Raies B r o n c h i q ues Arthralgies Hémoptysie 33,3 % i * ! 54 14,4 % 1 En somme, du point de vue radio-clinique, il s'agit d'une pneumoconiose d'apparition tardive (après 19 ans en moyenne) sans formes graves, ni association avec la tuberculose. La Symptomatologie clinique, quoique présente dans la majorité des cas, est quand même discrete et bien tolérée. c - PROFIL FONCTIONNEL 25 malades ont subi des explorations fonctionnelles plus poussées; 20 dossiers ont été retenus. l) Une spirometrie simple par soironranhe GODARD. - CU (capacité vitale) et nourc^ntaoe oar rarcort à la valeur théorioue; - UEMS et le raooort TIFFEMEAU - UT'lt'1 (volume m i n u t e ) . 2o2 2) Une nn7nmÄfrin nu reno.i sur éphanti ). Inn artériel nrélpv* 3D nivn.-iu 'In la f¿mpra.1 e (PaO-, PnTT-, P h ) . 70 rprnuun d'nffnrt trisnnut a j rn effectuée nn line seule r.fi.anr.r, nur er^orycla par palier de 3fin et ein durée dn 3 minutes, jusqu'à la tolérance maximale Mu sujet. flu cnurr, de la dernière minute, nn effectue un nrél fn/onçnt. do sann artériel au niveau de la radiale pour dosane den na? du sann (Pan , PaCOj, P h ) . rMçnm T/iT_ri FT noiw^JTAinr^: Au point de vue binloeique, nn note une tendance a la nn.1vrlnbu.lie (envirnn 5 300 OPP) par rapport au reste de la pnnulation. La spirometrie mnotre chez certains un léper syndrome obstructif (Tif.<6F> ^)»Tous sont ries fumeurs ou des priseurs de NETTA (tabac a priser). On ne note pas d9 syndrome restrictif (tableau 4 ) . La oazométrie au repos montre une logera perturbation de la PaP,J II s'anit d'une hvooxémie lécere qui ne s'accom- panne pas d'h»nercapnie. l'effort. Une amélioration est constatée a Ceci est vraisemblablement lié a 1'hyperventilation et la modificatinn du rannnrt VA. TT l'énreuve d'effort révèle une diminution de la PriT (nuissanco maximale tenue) (13P U nn moyenne). marquée (I1 n Cile est plus '•') chez les malader, présentant une dvsnnée. Cette limitatinn de l'effort chez nos malades ne s'explique nue partiellement par l'existence de svnrirome obstructif. (fio.]) et de la nazomét-rin 1éoeremept perturbé-- au renos (fin.?). 2o5 L'handican constata a l'effort Quantifia ne concorde pas avec les trouhlen fonctionnais ventilatnires enrsnistrés. Ceci laisse prévoir des mécanismes ohysio^atholnoioues oui se situent au delà de l'alvéole pulmonaires, vraisemblablement d'ordre vasculaire. Des études histoloniques pourraient éventuellement compléter ces observations. En conclusion, des données radio-cliniques ainsi que les constatations fonctionnelles plaident plutqt en faveur d'une pneumoconiose non collagene a type de sidérose-silicose d'aooarition tardive et d'évolution lente. 2o4 REFERENCES 1 ) AMTHOn'r.n. I.AMV.P.t HE REN. H.; PRP.IIM,P.; CERVONI.P.; PETIET. G.j„SCHJ.inRTJ.j_Jl.. et LAMAZE, R. : "Lo nancnr bronchi quo rien mineurs de fer do Lorraine (a nrnnns dn 270 nouveaux cas observés de 1964 a 1927)", XVemes .Tournées Nationales de Médecine du Traviai!, Strnsbnurn, 1(1-13 Hai 7R 7 ) E»EH, R.; SORS, 5. : "La pneumoconiose des mineurs de fer". Pressa Médicale, Mai 195B, 66 NS 46, 906-907 3 ) ENCYC. PlEOICflL - POUMON : 7.6D18 - 4 A 30 ) nUILLERM, .1.; MACINOT et SADOUL : "Le!caractéristiques anatomiques de la pneuraoconiose du mineur de fer et leurs conséquences fonctionnelles". Archives des maladies professionnelles, Hanv. - Février 1960 - 21, 21 MO 1-2, 62 5) MOSINSER, M. et Eoli : Archives des maladies professionnelles Danvier - Février 1968, NO 1 - 59-66 6) SAOOIIL, P.(1974) Sidérose pulmonaire in_ : Encyclopédie de médecine, d'hyniene et de sécurité du travail, vol II, pp. 1495-96. Bureau international du Travail, Heneve. 7 ) SADOUL, P. ET COLL. : Rapport : "Les pneumoconioses dans l'Est de la France", Xl/ëmes Tournées Nationales de Médecines du Travail, Strasbourg, 10-13 Mai 1978. 2o5 La neumoconiosis en una mina de hierro de Tunez. Aspectos clinicor-radiológicos v funcionales. G. Cornea, A. Ghachem, A. Ben Kheder, M. Maalej, J. Daghfous, H. Bou-Acha y L. El Mekki (Túnez) En una mina de hierro se ha llevado a cabo un control radiológico íntegro, habiéndose examinado a 1.240 obreros. Se han descubierto 90 casos de neumoconiosis. lo que representa el 7,2 por ciento del conjunto de los obreros y el 11,2 de los mineros de fondo. La proporción de S10» en el mineral no excede del 3 por ciento. La edad media de los enfermos es de 45 añosi la antigüedad en el puesto de trabajo, de 18 años, y la duración del trabajo en el martillo neumático, de 12 años. Los fumadores constituyen el 86 por ciento del total y los adictos al NEFFA (polvo de tabaco) el 13 por ciento. En el plano clínico se observa la presencia de la disnea en 70 por ciento de los casos, de tos blanda en el 64 por ciento, de broncoespasmos en el 33 por ciento, de la artralgia en el 54 por ciento y de la hemoptisis en el 14 por ciento (sin explicación clara). En el plano radiológico se observan imágenes puntiformes, finas y apretadas en la mayoría de los casos (fase p 60,1 por ciento;. Incluso en las formas micronodulares (fase o, 33,3 por ciento) y nodulares (fase r 5,5 por ciento), el aspecto es denso pero sin tendencia a la confluencia; no existe asociación con la tuberculosis ni cáncer pulmonar entre los mineros examinados. A 25 de ellos se les ha sometido a exploraciones funcionales más completasi espirograffa simple, gasometría en descanso y prueba de esfuerzo triangular con gasometría durante el esfuerzo. Resultados« Se advierte una ligera poliglobulla (5.300.000) con respecto al resto de la población. Una espirografía al límite fisiológico (sin obstrucción bronquial importante). La prueba durante el esfuerzo muestra una baja relati- 2o6 va de la PMS (potencia máxima sostenida)» Soportaron como promedio 130 W. La disminución de la PMS es más manifiesta entre los neumoconlótlcos dlsnelcos (110-W), si bien la espirometría y la gasometría no revelan anomalía alguna en reposo ni durante el esfuerzo. En conclusión, el aspecto cllnlcorradlológlco y el perfil funcional permiten prever más bien una neumoconlosls no colágena del tipo de slderosls o slderoslllcosis. 2o7 Man-made mineral fibres» Joint European Medical Research Project C. E. Rossiter, J. C. Wagner MRC Pneumoconiosis Unit, Penarth, United Kingdom J. Dodgson Institute of Occupational Medicine, Edinburgh, United Kingdom R. Saracci International Agency for Research on Cancer, Lyon, France It is now just 100 years since the commercial mining of asbestos was started, and its hazards to human health and life are well known. The hazards were thought to be due to some proper- ty in asbestos which was unlikely to be present in other mineral fibres. However, animal experiments with fibres of different sizes and diameters (Wagner, 1966i Stanton Sc Wrench, 1972« Pott & Friedrichs, 1972) suggested that all fibres which are rigid rather than curly, fine (less than 3¿jm in diameter) and long (at least 10 /um) are likely to have dangerous biological activity. Follow-up studies resulting from the report from Turkey (Baris et al, 1978) suggest that fibres other than asbestos may be dangerous to humans, as well as experimental animals. With the thought that fibre morphology may be more important than chemical composition, it is natural for interest to focus on the possible hazards of fibrous materials used as replacements for asbestos, such as calcium silicate, ceramic fibres and man-made mineral fibres (glass fibre, glass wool, rock wool and slag wool). Particularly following the report by Stanton and Wrench (1972) of mesotheliomas being induced in rats by the intrapleural implantation of a wide range of fibres, the manufacturers of manmade mineral fibres in Europe and in the United States of America, 2o9 decided to support research into possible respiratory health hazards occurring during the production of these fibres. Current information on health hazards of man-made mineral fibres Man-made mineral fibres have many uses. For textiles and for reinforcement of plastics the fibres are produced by drawing molten glass and hence they have a relatively narrow range of diameters, about 10-25/jm. For insulation purposes the fibre wool is created by a combination of blowing and centrifugal force with a target diameter of about (yum, but there may be a proportion of respiratale fibres present. For some lightweight and acoustical insu- lation purposes, the nominal diameter may be less than 2um. Pro- duction for other specialised purposes makes up about l%-2% of total output. However despite the many years of production of these fibres, very little evidence of human disease has been that of the dust acting as a skin irritant. publised apart from Hill (1977) has re- viewed the literature and reports only 9 cases of respiratory disease in any way attributed to exposure to man-made mineral fibres. Upper respiratory tract irritation also occurs occasional- ly but none with lung involvement. In 8 detailed epidemiological studies in U.S.A., Sweden and U.K. no evidence of human disease was reported, except that in one study there were 3 retirements due to bronchitis, compared to 0.5 expected, and in a second there was an excess of nonmalignant respiratory deaths, excluding pneumonia and influenza. However, this latter study has been criticised because the expected 21o number of deaths for the industrial group was based on all white male Caucasians in U.S.A. including the country dwellers. Several animal experiments have been carried out, and although a few have shown that inhalation or intratracheal injection of man-made mineral fibres does sometimes cause minimal fibrosis, the general concensus has been that these fibres are biologically inert, with the reaction being one of macrophage mobilisation. However, in the Intrapleural implantation studies by Stanton and Wrench (1972) and Pott and Friedrichs (1972), it was found that glass fibres, as for all tested fibres, produced mesothelioma in rats if the fibres were fine enough and long enough. More recent studies have confirmed these findings. The European Medical Research Project Cameron (1977) has described the formation of the Joint European Medical Research Board following the decision by two trade associations* within the man-made mineral fibre industry to support medical research into possible health risks. After consultations with interested scientists, it was agreed that any research programme had to be independent of the industry. Thus the contracts with the International Agency for Research on Cancer, the Institute of Occupational Medicine and the British Medical Research Council provide for the payment of agreed amounts to these institutions as contributions towards the cost of the research to be carried out and for the findings to be published with complete scientific freedom. To coordinate the research programme * Glass Fibre Producers' Group of the Comité International de la Rayonne et des Fibres Synthétiques. European Insulation Manufacturers' Association. 211 there Is a scientific committee with representatives from the three research teams, an independent chairman and a trade union medical adviser, who reports to the International Confederation of Free Trade Unions. Epidemiological studies The research team from the International Agency for Research on Cancer have visited very nearly all the 72 man-made mineral fibre production plants in Europei For the historical follow-up mortality studies, 13 of these plants with a total population of about 10,000 have been chosed which satisfy four criteria for inclusioni 1. duration of manufacture at least 20 years i 2. diameter of some fibres known to be less than 6LUK; 3. complete intact records of exposed personnel; 4. only man-made mineral fibres produced. Nominal rolls of past and present employees at these plants are currently being prepared, so that death records may be obtained. Each nominal roll will be sent, where possible, to an investigator with access to national death records who will prepare the necessary data for the complete mortality analyses. Personal identification data will not be sent across national boundaries. These mortality analyses are expected to be complete by the end of 1981. In most countries, the national investigator is a member of a national death or cancer registry or a University epidemiologist with access to death records. However, one French company to be studied has very good personnel records, but French regulations do not currently permit access to national death records. This is a problem which has also prevented the inclusion of plants in some other European countries into *"v,~ •»«»-•!•«i.ed studies. The increasing 212 need for international studies of the health hazards of a wide range of products and materials should be used to persuade all countries to provide access to death certificates for bona fide research purposes. As experience from the visits to the various plants has developed, the research team has been preparing a standard form of personnel record including the minimum data required for further prospective studies, should these be required. All companies are being recommended to collect this minimum set of data for each current and new employee. Environmental studies At the Institute of Occupational Medicine, techniques for the environmental sampling of airborne dust in man -made mineral fibre production plants are being developed as part of their continuing research programme. For routine sampling in factories, a standard method to assess full shift dust exposure using personal membrane filter samplers has been recommended for adoption by all the European plants. This method is a modification of that commonly used for asbestos monitoring and provides fibre number and total mass concentrations over an 8-hour period. The environmental monitoring team will eventually have visited all 13 plants included in the epidemiological studies and a further 3 to extend knowledge about dust levels relative to type of fibre manufactured and age of plant. Preliminary visits are made to each plant to discuss openly with management and union representatives why sampling is to be undertaken and to ask for the cooperation of the workers. For the actual sampling, workers within each 213 production zone are selected at random to wear the personal samplers, and large volume static samplers are set up at pre-determined positions to permit comparisons between plants. Sampling continues for up to 3 weeks, with about 200 samples being taken. Usually within 4 weeks a preliminary report on the results is sent back to be made available to everybody in the plant, and a final report is sent when all the analyses have been completed. The dust analyses are expected to be completed during 1980 when technical reports and the results of collaborative studies with various national environmental sampling groups will be published. The results will also, of course, be made available to the epi- demiologists so that estimates of dose-response relations may be made. Animal experimental studies As part of its general interest in the biological effects of fibres, the MRC Pneumoconiosis Unit is carrying out inhalation and intrapleural implantation studies of man-made fibres using rats. In the implantation studies 20mg samples of glass wool, rock wool or slag wool with and without resin coating, and glass fibre, each suspended in saline, have been injected into the right pleural cavity and the rats are being allowed to live out their lives. Comparisons of the results of concomitant studies of chrysotile asbestos and saline alone will be made. This experiment started in December 1976, and as the rats may survive over 3 years, the resulti are expected sometime in 1980. The inhalation studies are being carried out cooperatively with the National Institute of Environmental Health Sciences, U.S.A. Similar dusting chambers are being used with rats from the same 214 source and with certain dusts in common so that direct comparisons may be made. At the MRC Pneumoconiosis Unit exposure will be for one year to equal respirable mass concentrations of glass fibre, glass wool with and exposed controls. without resin coating or rock wool, with un- From this it will be possible to determine the amount of dust deposited and the fibrogenic effects. retained over definite periods and In addition, by sacrificing some animals after 3 months exposure, at the end of exposure and 12 months later, it will be possible to indicate whether any fibrosis is progressive. The majority of the animals will be allowed to survive their full lifespan. At death they will all receive detailed examination and the findings will be recorded, including all tumours, whether or not associated with the exposure. Comparisons will be made with parallel studies of asbestos-exposed animals. These experiments started in October 1977, so that exposure has just finished. Final results are not expected for at least two years. Outside the research support by the Joint European Medical Research Board, cell biology studies are being directed towards the development of in vitro tests for cytotoxicity and fibrogenicity of mineral fibres, whether man-made or naturally occurring. Considerable progress in the cytotoxicity tests has been made using techniques for adding mineral fibres to cell cultures of Chinese hamster lung cells (V79-4), and in the fibrogenicity tests by studying the selective release of lysosomal enzymes from exposed macrophages. Comments Past evidence of adverse human response to exposure to airborne 215 man-made mineral fibres is essentially negative. This could perhaps be because the sizes of fibres being produced thirty or more years ago were generally too coarse for many to be respiratale, or indeed because man-made mineral fibres do not in fact present a hazard to man when inhaled. However, it is now in- cumbent upon industry to ensure that its products are safe before they are shown to be otherwise. Thus the man-made mineral fibre production industry decided to support independent research into possible health hazards on a pan-European basis. This is probably the first time that such a large international independent research programme has been undertaken without prior evidence of human disease. 216 ' References BARIS, Y.I., SAHIN, A.A., OZESMI, M., KERSE, I., OZEN, E., , KOLACAN, B., ALTINORS, M., and GÖKTEPELI, A. (1978) An outbreak of pleural mesothelioma and chronic fibrosing pleurisy in the village of Karain/Ürgüp in Anatolia. Thorax, 33., 181-192 CAMERON, J.D. (1977) Man-made mineral fibres: medical research - CIRFS/EURIMA initiative. Annals of occupational Hygiene, £0, 149-152. HILL, J.W. (1977) Health aspects of man-made mineral fibres. A review. Annals of occupational Hygiene, 20, 161-173. POTT, F. and FRIEDRICHS, K.H, (1972). Tumoren der Ratte nach i.p. Injektion faserförmiger St'áube Naturwissenschaften, 59, 318. STANTON, M.F. and WRENCH, C. (1972). Mechanisms of mesothelioma induction with asbestos and fibrous glass. Journal of the Rational Cancer Institute, 48, 797-821. WAGNER, J.C. (1966). The induction of tumours by the intrapleural inoculations of various types of asbestos dust. In: Lung Tumours in Animals. Proceedings of the Third Quadrennial International Conference on Cancer, Perugia, June 1965. (ed: SEVERI, L.) University of Perugia.Division of Cancer Research, Perugia. 589-606. 217 Fibras sintéticas i provecto médico europeo de investigación. C. E. Rossiter (Reino Unido), J. Dodgson (Reino Unido), R. Saracci (Francia) y J. C. Wagner (Reino Unido) Se ha establecido un programa de investigaciones sobre los riesgos para la salud que puede presentar la fabricación de fibras sintéticas. Ese programa cuenta con el auspicio de dos importantes empresas de esa industria, la cual, por otra parte, no ejerce ningún control sobre los detalles de las decisiones y la publicación de los resultados de los trabajos. El grupo de especialistas en epidemiología visitó prácticamente todas las plantas europeas de fabricación antes de seleccionar a trece, que reúnen los criterios necesarios para una investigación continuada. Dichos establecimientos están siendo estudiados en colaboración con los registros de cáncer y las oficinas nacionales de estadísticas. Se presentan algunos problemas en los países que no permiten consultar los certificados de defunción. En las mismas plantas están reuniéndose muestras a fin de evaluar los niveles de exposición que permitan establecer estimaciones de la relación dosis-respuesta. Se ha recomendado una técnica uniforme de muestreo para su utilización en todas las plantas de producción de fibras sintéticas de Europa. Se han iniciado también estudios complementarios de experimentación sobre animales acerca de los efectos de la inhalación y la inoculación intrapleural de fibras sintéticas, así como un programa para desarrollar pruebas "in vitro" para determinar los efectos fibrogénicos, cancerígenos y mutagénicos de las fibras. Se estima que ésta es la primera vez que se inicia una investigación de esta magnitud sobre un posible riesgo para la salud sin que exista prueba concreta de efectos en los seres humanos. 218 4> CHRONIC LUNG DISEASE IN THE FURNITURE INDUSTRYt AN EPIDEMIOLOGIC STUDY DESIGN 1. D.F. Goldsmith, Department of Epidemiology, University of North Carolina Chapel Hill, North Carolina U.S.A. 2. J.F. Gamble National Institute of Occupational Safety and Health Morgantown, West Virginia U.S.A. 3. N. Stroup Department of Epidemiology, Havard School of Public Health Boston, Massachusetts U.S.A. 4. C M . Shy Department of Epidemiology, University of North Carolina Chapel Hill, North Carolina U.S.A. INTRODUCTION Employment in the furniture and wood products industries is associated with several chronic diseases) nasal cancer (1,2), Hodgkin's disease (3), prostate cancer (4), occupational asthma (5, 6), dermatitis (7), and physical disabilities resulting from forestry accidents (8). In this paper we will review the epidemiologic methods to be used in a study of respiratory disease (asthma, bronchitis, and emphysema) as a result of employment in the furniture industry. The same methodological considerations would apply to other chronic diseases such as nasal cancer or Hodgkin's disease. It is hypothesized that exposure to wood dust is of etiologic significance in the occurrence of respiratory disease and other chronic illnesses, particularly nasal cancer. In this regard the wood dusts must be evaluated for both types of wood (either soft or hard) and particle size, greater than 5 microns and less than 5 microns (respirable size). This study is important for two major reasons i 1) there have been no thorough epidemiologic studies of chronic disease from exposure to wood dusts in the United States; and 2) the U.S. government agencies responsible for safeguarding workers' health are evaluating the present wood dust 219 Standard to judge whether a stricter one Is warranted on the basts of present epidemiologic findings. Previous Findings A review of the literature indicated three basic areas of research on wood dust i respiratory effects, nasal cancer, and measurements of exposure to dusts in the furniture industry. Respiratory Effects Early findings of respiratory effects from wood dust were limited to case reports. In 1949 Ordman reported that the symptoms of rhinitis and asthma varied according to the wood used by a cabinet maker (10). His symptoms appeared after substitution of western red cedar, kejatt, iroko, "Congo hardwood" and panga panga in his wood working. Sosman (1969) described the asthmatic symptoms of four woodworkers (11). One patient showed a markedly reduced forced vital capacity (FVC) and expiratory flow rates when exposed to oak dust or its alcohol extract. A second patient had a broncho-spastic reaction to mahogany dust, characterized by a reduced lung capacity and wheezing. The other two workers reacted to cedar dust. The author suggested that an hypersensitivity reaction was responsible for the findings in all four patients. Booth et al., and Mitchell reported pulmonary hypersensitivity among workers exposed to a abiruana dust and western red cedar, respectively (12, 13). In the case report by Mitchell, the patient's forced expiratory volume (FEV) was reduced by 53% within five minutes in a bronchial challenge test with western red cedar. The patient's asthma attacks subsided after occupational exposure to western red cedar dust stopped. 22o Woodworkers' asthma has been reported in relation to 9 species of tree including oak, western red cedar, cedar of Lebanon, mahogany and California redwood. The allergic responses have been both immediate and delayed hypersensitivity reactions. In many cases the results of skin scratch tests and intradermal injections were equivocal. Although measurements of lung function often showed precipitous decrements, these effects appeared to be transitory, and normal function returned after the workers were removed from the wood dust exposure. However, no lengthy follow-up has been conducted on any population of woodworkers. Nasal Cancer The pioneering work by Acheson led to the finding of a strong association between furniture making and adenocarcinoma of nasal sinuses. His findings centred on the chair-making industry in High Wycombe area near Oxford, England (l). Subsequent findings have confirmed this association in many countries including the United States, Holland, Germany, Belgium, France, Denmark, Australia and Italy (14-22). The work histories of the chair-makers from High Wycombe suggested a mean latency period from first exposure to diagnosis to be 40-49 years (1). The time of greatest risk was from the 1920's up to at least World War II. Occupational exposure to hard woods was strongly suspected of being the etiologic agent in most reports. These woods are beech, elm, mahogany, walnut in England and teak in Denmark. Subsequent research has turned up a further observation concerning wood dust. Those who are exposed had impaired mucociliary clearance mechanisms, that is, these workers had a significantly 221 longer nasal clearance time than controls not occupâtionally exposed to wood dust (23). In addition, many of these men had squamous metaplastic cells when cytologic exams were conduced of the middle turbinates (24). Concentrations of Wood Dust It is of considerable interest that there is a sizeable fraction of wood dust in the respirable range, less than five microns. Hounam and Williams conducted personal and area samplings in several machining operations in High Wycombe (25)., They reported that average wood dust concentrations, measured by personal samplers, of less than 6 mg/m for the following operations: band or circular sawing, planing, routing, spindle-turning, and furniture assembly. The average was greater than 6 mg/m sanding jobs and in the turning operations. overall average was 20.1 mg/m in the Using area samples the near the sawing areas, while lower concentrations were recorded In the other operations. About 25% of the dust from area samplers was smaller than five microns in diameter. The finest dust was collected in the sanding and assembly jobs while the coarsest was found in the sawing operations. Anderson (2) conducted a parallel investigation of particle sizes with a cohort of 68 furniture workers in Denmark. From high volume area samplers he reported that 33% of the dust measured less than 5yum In diameter. Thirty-seven percent of the personal 3 "Î samples were less than 5 mg/m and 63% were greater than 5 mg/m . The average for the sanding jobs (by hand or machine) was 14.3 mg/m , while the drilling, planing, and sawing jobs had an average dust 3 level of 5.2 mg/m . 222 The Danish workers were divided into two groups exposed to an average of greater or less than 5 mg/m dust mostly teak. of several types of wood Those exposed to the higher dust levels report- ed greater prevalence of the following symptoms» sinusitis, pro- longed colds, asthma, nose bleeds, frequent sneezing, and nasal itching and nasal obstruction. The proportion of workers with middle ear inflammation was significantly higher among those exposed to the higher dust concentrations. FEV and FEV25-75% did not differ between the two groups. However, Anderson et al did not conduct pre- and post-work day measures of FEV. They measured mucociliary transport by placing a blue-stained particle of saccharin in the nose on the turbinate. Normal clearance was judged to be the appearance of blue in the oropharynx within forty minutes. There was a clear inverse gradient indicating that those exposed to the greatest concentrations of wood dust had the poorest levels of nasal clearance. It should be noted that six out of nine workers with mucostasis had normal clearance when away from work for the weekend. Table I summarizes the present knowledge about respiratory disease and wood dusts. Wood dusts are associated with occupational asthma and hypersensitivity, particularly western red cedar. Exposure to dusts from some hard woods (such as beech and teak) used in furniture-making is a strong factor in the cause of adenocarcinoma of the nasal sinuses. Respiratory function and mucociliary clearance are reduced in workers exposed to higher concentrations often in sanding and finishing work. found Prior studies have indicated that as much as one-third of the dust generated may be in the respirable fraction of 5um or less. 223 Study Design Alternatives In order to assess the risk of respiratory disease from exposure to wood dust there are three possible methods i a prospective model, a retrospective model and a cross-sectional or prevalence study. The prospective model is seen in Table 2. It begins by sampling a group of exposed and unexposed workers who are healthy, and who, it is thought, represent the whole population of furniture workers. These individuals are then followed for a period from time To to time T. At the close of the study T., the investigators examine the morbidity and or mortality of both groups for the proportion diseased conditional on exposure. If exposure to wood dust is a true causal factor then the incidence of the disease will be higher in the exposed group that in the unexposed one. One can then calcu- late a relative risk with appropriate confidence intervals to test for significance. A major drawback to this study is the loss of subjects whose health status cannot be determined. In general, this model is slow and can be very costly in time and money. Table 3 shows an alternative approach, the retrospective or case-control study, which is generally cheaper and less wasteful of resources. It starts with participants whose disease state is known and compares their past exposure to that of a control group of individuals without disease. This is the opposite of the prospective model in that it calculates exposure conditional on disease status. Utilizing Bayes' Theorem, one then calculates the odds ratio and attendent confidence intervals to determine whether the result is statistically significant. Table 3 also illustrates the cross-sectional or prevalence study. In this study one calculates a prevalence ratio, that is 224 the prevalence of diseased individuals given exposure compared to the ratio of diseased subjects who lack the exposure. However, there are two major difficulties with this method. The investigator may be dealing with a sample of surviving workers who have neither left the industry because of health problems nor been disabled. Also in a eross-sectional study one is unsure whether the exposure preceded or followed the disease. For example, a researcher may find that obese individuals use saccharin more than normal weight persons. Is saccharin used to help lose weight or as a palliative to justify not reducing calories? Four Ma jor Obstacles In testing the null hypothesis of no association between wood dust and chronic respiratory disease there are four major obstacles to an appropriate study design. They are seen in Table 4i 1) access to a large and stable population of furniture workers with accurate personnel records, the necessary follow-up information such as death certificates for a mortality study or hospital or clinic records for a morbidity studys 2) selection of an appropriate set of controls who lack the disease of interest, but have an equal probability of exposure. In this example, a case group of asthmatics would require a control group of non-respiratory cancers or perhaps healthy Individuals! 3) adjustment for the likely confounding by the presence of other factors which may be associated with the exposure, and are independent risk factors for the disease. Some 225 of these are race, age, smoking habits, alcohol consumption, previous occupations, length of employment in the furniture industry, and off-the-job hobbies. The list should also include genetic susciptibility and a history of other allergies. If these are uncontrolled they may lead to a biased estimate of risk¡ and 4) in measurements of exposure to wood dust, both the types of wood and partitele sizes are necessary for accurate risk assessment. The investigator may have to rely on surrogate measures of exposure such as work histories or production records which supply the dates when stocks were introduced and discontinued. Furthermore, a leap of faith must be made in assuming present measurements are equivalent to exposures occurring ten or twenty years before. These limitations for accurate study design also apply to any research on occupational cancer in the wood industry. In addition it is unlikely that a sufficient number of cases of nasal cancer could be found to conduct a prospective or retrospective study of this tumour. Study Design Selected The primary question isi is wood dust associated with respiratory disease? There are four "branches" of the industry we wish to evaluate which are characterized by wood type and particle sizei 1) small particle, hard wood) 2) small particle, soft woodt 3) large particle, hard wood¡ and 4) large particle, soft wood. It may not be possible to obtain large cohorts of workers with homogenous exposures, so that mixed exposures may be necessary. 226 In each eligible plant we wish to do two things. First, we wish to conduct a retrospective case-control study of mortality from chronic lung disease (bronchitis, asthma, and emphysema) comparing work histories of these men with those who died from other diseases, excluding lung cancer and other pneumoconioses. Our goal is to see if these men had a higher likelihood of working in the sanding jobs than the controls. Adjustment must be made for the confounding factors previously mentioned. Those types of data must be obtained by questioning relatives and personal physicians. Secondly, we will conduct lung function tests, specifically volumes and flows from forced expiratory measures such as FEV, FVC, and FEF 50%. This is a prevalence or crass-sectional study, and will be conducted before work and after completion of the workshift to measure change over the course of the working day. These data will be correlated with environmental samples of wood dust and volatiles used in painting, glueing, and varnishing. The lung function tests will be accompanied by a modified MRC questionnaire and an extensive questionnaire to measure the confounding variables previously noted. The questionnaire will also ask about acute symptomatology or other respiratory diseases (such as difficulty of breathing when walking with peers). It is expected that 200 individuals from each wood dust exposure group will be compared with two control groups composed of finish applyers, i.e. painters and varnishers, and nonproduction employees such as transportation or supervisory personnel. If wood dust is a factor, in changes in pulmonary function these tests might provide an early indication of 227 susceptibility so that abnormal changes may be reversed. If this is the case, this may provide dose-response information on which to base a new dust standard. 228 BIBLIOGRAPHY Aohoson, E.D., R.H. Cowdell, E.Hadfield, R.O. Macbeth', 1968. Nasal cancer in woodworkers in the furniture industry. Br. lied. J. 2:587-596 Andersen, H C l . Andersen, J. Solgaard. 1977.' Nasal cancer«, symptoms and upper airway function in woodworkers. Br. J. Ind. Med, 34:201-07 Peterson, G.R., S. Hilham, Jr. 1974. Brief communication— Hodgkirr's disease mortality and occupational exposure to wood. J. Natl. Cancer Inst. 53:957-58 Hilham, S'. Jr. 1976. Neoplasia in the wood and pulp industry. Ann. NY. Acad. Sci. 271:294-300 Hilham, S'. 1976. Occupational Mortality in Washington State, 1950-1971. Vol 1-3. U.S. Department of Health, Education, and Welfare (Public Health Service), Washington, B.C. U.S. Government Printing Offico, I976 Gandevia, B., J. Milne. 1970. Occupational asthma and rhinitis due to Western red cedar (Thu'ja plicata), with special reference to bronchial reactivity. Br. J. Ind. Med. 27:235-44 Suskind R.R. I967. Dermatitis in the forest produot industries. Arch. Environ, Health 15:322-26 Social Security Administration, 1967. Occupational Characteristics of Disabled Workers, by Disabling Condition. U.S. Government Printing Office, Washington, D.C. 307 pp. U.S. Department of Health,' Education, and Welfare, Public Health Center for Disease Control, 197°. NIOSH' Criteria for a Recommended Standard. Occupational Exposure to Wood Dust, (first draft) U.S. Department of Health, Education, and Welfare, Washington, B.C. June 23, 1978 Ordman, D.' 1949. Bronchial asthma caused by the inhalation of wood dust. Ann. Allergy 7:492-96,505 Sosman A.J., D.P. Sclueter, J'.N. Fink, J.J'. Barboriak. 1969» Hypersensitivity to wood dust. N. Engl. J. lied. 281:977-80 Booth, B. H-., R. H. LePoldt,'E. H. Hoffitt. 1976. Wood dust hypersensitivity, J. Allergy Clin. Immunol. 57:352-357 229 * M i t c h e l l , C. 1970. Occupational' asthma due t o Western or Canadian red cedar (Thuja p l i c a t a ) . Med. J , Aust. 2:233-35 B r i n t o n , L. A . , W.J. B l o t t , B . J . S t o n e s , J . P . Fraumeni J r . 1977. A death c e r t i f i c a t e a n a l y s i s of n a s a l cancer among f u r n i t u r e workers in North C a r o l i n a . Cancer Res. 37:3473-74 Delemarre, J . P . I ! . , H.H.' Themans. 197L Adenocarcinoma of t h e n a s a l c a v i t i e s . * Ned. T i j d s h r , Geneeskd 115:668-90 L o f f l e r , P. 1972. Adenocarcinomas i n t h e nose and paranasal s i n u s e s . MonatsschrOhrahoilkde Laryngo Rhinol 106:529-31 Debois, J.II. 1969.' Tumors of t h e nasal c a v i t y i n woodworkers.. T i j d s c h r . Geneeskd. 25:92-93 Leroux-Robert, J'. 1974. Cancer of the n a s a l c a v i t y in woodworkers. B u l l . Acad. N a t l . Med. P a r i s . 158:53-59 Gignous M. , ' P . Bernard. 1972. Malignant tumors of t h e ethmoid among woodworkers. J . Med. Lyon. 50:731-36 Mosbach, J , , and E.D. Achesoh. 1971= Nasal cancer i n f u r n i t u r e makers in Benmark. Dan. Med. B u l l . 18:34-35 I r o n s i d e P. and J . Matthews, 1975. Adenocarcinoma of t h e nose and paranasal s i n u s e s in woodworkers i n tho s t a t e of V i c t o r i a , A u s t r a l i a , Cancer (Brussels) 36:1115-21 D i g i e s i V. 1972. Bronchiolar ( a l v e o l a r cfcll) carcinoma complicated by spontaneous pneumothorx i n a woodworker. Prog. Med. (Rome) 28:614-19 Black, A'., J . C . ' Evans, E.H. Hadfield, R.G. Macbeth, A. Morgan, M. Walsh. 1974. Impairment of nasal' mucociliary c l e a r a n c e i n woodworkers i n t h e f u r n i t u r e i n d u s t r y . B r . J . I n d . Med. 31:10-17 Hadfield, E, H. 1970. A study of adenocarcinoma of the p a r a n a s a l s i n u s e s i n woodworkers i n t h e f u r n i t u r e i n d u s t r y . Ann. R. C o l l . Surg. Engl. 46:301-19 Hounam P . R . , and J . Williams. 1974. Levels of a i r b o r n e dust i n f u r n i t u r e making f a c t o r i e s in the High Wycombe a r e a . B r . J . I n d . Med. 31:1-9. 230 TABLE 1 - SUMMARY OF LITERATURE ON RESPIRATORY DISEASE AND WOOD DUST 1) Associated with respiratory asthma and bronchial hypersensitivity, particularly exposyre to wester red cedar. Reaction may be due to immune response. 2) Exposure to hard woods, such as beech, used in furniture making is strongly associated with adenocarcinoma of the nasal sinuses. 3) Respiratory function and mucociliary clearance appear to be affected by elevated dust concentrations found in sanding and finishing jobs. 4) Studies suggest that as much as one-third of the dust may be in the respirable fraction of fyan or less. 231 TABLE 3 -ASSESSING DISEASE RISK IN A RETROSPECTIVE CASE/CONTROL STUDY Exposed E/D Case D Unexposed S/D Representative of PAR? Exposed E/5 Control D Odds Ratio (OR) = (from Bayes Theorem) (E/D) X (Ë/D) (S/D) X (E/D) Unexposed Ë/5 Tl To TABLE 2 - ASSESSING DISEASE RISK IN A PROSPECTIVE STUDY Diseased u/E Exposed (E) Populatioi a t Risk (PAR) Healthy 5/E Diseased D/S R e l a t i v e Risk (RR)= D/E (P/E) + (5/E) Unexposed (§) Healthy D/f T l 232 D/Ë (D/S) + (5/Ë) TABLE 4 - POUR IIAJOR OBSTACLES TO APPROPRIATE STUDY SESIÓN 1) Access to a large and stable population of furniture workers with death certificates or hospital records for accurate follow-up of vital status 2) Selection of appropriate set of controls 3) Adjustment for probable confounding variables which are associated with exposure and a risk factor for respiratory disease 4) a) age e) prior occupations, such as coal mining or asbestos exposure b) race f) length of employment in the furniture industry c) smoking h a b i t s g) d) alcohol consumption o f f - t h e - j o b hobbies such as furniture refinishing. Measurements of exposure t o wood dust a) types of woods b) c o n c e n t r a t i o n s of d u s t - t h e proportion < 5jjm c) type of o p e r a t i o n such as Banding or sawing d) s u r r o g a t e measures of exposure such a s work h i s t o r i e s 233 Enfermedades pulmonares crónicas en la industria del mueble i estudio epidemiolop.ico . Goldsmith, D. F., N. Stroup, J. F. Gamble y C. M. Shy (Estados Unidos) Se sospecha que el polvo de madera es un carcinógeno de los senos nasales. Ciertos polvos de madera pueden provocar ataques asmáticos e hipersensibilidad pulmonar. Los trabajadores de la madera corren mayor riesgo de cáncer del sistema linfático y hematopoiético y de tuberculosis. Los trabajadores del mueble expuestos a diversos niveles de polvo de madera presentan altas tasas de tos y expectoración, resfríos comunes, estornudos, irritación de la mucosa nasal, sinusitis y conjuntivitis. La finalidad de este estudio es presentar una reseña de la literatura existente sobre los efectos del polvo de madera sobre la función pulmonar y describir los métodos epidemiológicos de evaluación de los riesgos de neuraopatías crónicas en la industria del mueble. La literatura existente revela claramente que en el proceso de fabricación de muebles, el aserrado, lijado, cepillado y taladro producen polvos de madera respirables (5>üm). Se consider» la neuropatía crónica como una con- secuencia de la exposición múltiple al polvo de madera, humo, los productos de acabado (pinturas, barnices, lacas 234 y dlluyentes) y el alcohol• y de los trabajos anteriormente desempeñados• El propósito de este estudio es identificar en la industria del mueble los sectores de mayor riesgo> mediante una estrategia epidemiológica multifacéticaí 1) evaluar la mortalidad por neumopatfas crónicas en los condados de Estados Unidos en que predomina la industria del muebleí 2) identificar los sectores laborales que se sospecha pre- sentan mayores riesgos mediante un estudio retrospectivo de control de casos dentro de una fabrica de muebles i 3) emprender un test de la función pulmonar entre los tra- bajadores en actividad comparándolos con muestras ambientales de polvo de madera y de productos de acabado. Un descenso en elVEFj al cabo de un turno de ocho horas puede indicar un futuro riesgo de enfermedad crónica. 235 PULMONARY DISEASE DUE TO PROTEOLYTIC ENZYMES M. L. H. Flindt United Kingdom I will first bring up to date the story in respect of the "detergent enzymes" before referring to the newer problems of the meat tenderisers. My initial work(l) showed that workers could become sensitised to, and develop allergic illness from, detergent enzyme powders and that the responsible allergen was in the enzyme component of the commercial preparations used. By skin prick-tests following inactivation of the enzyme, it was also shown that this allergenic effect was independent of proteolytic activity. There was no evidence that the viable spores of Bacillus subtilis, which at that time were contaminating the commercial preparations, were in themselves a source of illness, whether infection or allergy, it being thought that the weak prick-test reactions to spore extracts were probably due to the enzyme itself, as this was produced by, and inseparable from, our spore cultures. It was not thought likely that there was a problem of autosensitisation following tissue damage by the proteases, but it was considered that, as well as being capable of causing allergic illness, these powders could cause primary irritant effects on the respiratory tract, the clinical manifestations being throat and chest pain, haemoptysis and epistaxis. At the time, the possibility that there might be problems, independently or in association, from the various other ingredients of detergent enzyme powders was also considered. My ex- perience, over several years, had been that the detergents'and 257 additives in themselves did not appear to cause asthma or other allergic respiratory effects, although the non-soap detergents could cause primary irritant effects, including epistaxis. Whether or not adjuvant effects were occurring, these could not have been an essential factor leading to illness, as sensitisation and asthma had also occurred in development workers who had handled the enzyme material prior to the incorporation of additives. However, it is interesting to note that research has confirmed(2) that detergents can indeed act as immunological adjuvants, potentially capable of enhancing the allergenic consequences of enzyme inhalation. As regards the immunological mechanisms causing the symptoms, the case histories of asthma, and the immediate reactions to skin prick-tests, later confirmed by RAST tests for specific IgE(3), made it seem probable that reagin-mediated type I responses of Gell and Coombs(4) were occurring. What was not conclusively demonstrated in the early work by myself, and by Professor Pepys and his colleagues at the Brompton Hospital, was the nature of the late responses, occurring in some of the workers a few hours after exposure to the enzymes, and causing the dual response in challenge tests(5). There was understandable concern in the early days that these late responses might be due to type III precipitin-mediated reactions of Gell and Coombs. Such reactions, while capable of causing an acute alveolitis within a few hours of exposure to an allergen, can also lead to delayed fibrotic lung changes(6) causing impaired gas transfer. This consequence is not confined to those who have had clinical illness, but may occur insidiously following repeated 238 smaller exposures to antigen(7). In addition to the late reactions which were occurring under factory conditions, and on challenge tests, others as well as myself have obtained, in a small number of individuals, late reactions to prick-tests which, in appearance and timing, seemed indistinguishable from the so-called Arthus reaction, a manifestation of type III allergy. However, these late re- actions followed on from typical immediate reactions and may also have been primarily due to IgE-mediated type I mechanisms, as has been postulated in another context(8). In my original cases it had been possible to demonstrate precipitins when enzyme solutions were tested against the sera of some of the affected detergent workers. This might have supported the possibility that type III reactions were occurring, but the finding of similar reactions in the sera of a similar proportion of unexposed control individuals reduced, but did not exclude, the likelihood. In addition, the absence of conclu- sive radiological changes in the chests of the affected workers was against the likelihood of type III effects, although this did not wholly preclude them because few individuals were X-rayed during their acute illnesses, and transitory radiopacity from cellular infiltration might have been missed. It is now thought likely that the precipitins demonstrated were not due to immunological interaction between the enzyme as an antigen and antibodies in the serum, but to interaction between the enzyme as a protease and serum antiproteases(3). It cannot be said that type III reactions do not and cannot 239 occur following inhalation of B. subtilis proteases, for IgG antibodies have been demonstrated, but the predominant problem appears to have been due to IgE-mediated asthma. In the majority of cases removal from exposure has led to complete resolution of obstructive pulmonary effects, but this has sometimes taken several months. The reduced lung gas transfer found in some of the cases does not necessarily indicate an alveolitis, as it may represent the small airway component of an obstructive condition, Although, by taking stringent precautions, those who continue to use the material have substantially reduced the incidence of overt illness, it is important not to become complacent about it. Some of the initial fears were allayed, not on account of its harmlessness, but on account of the precautions taken. treshold limit value(9) of 0.00006 mg/m The ACGIH gives some indication of the care required, the figure approaching the limit of detectability and going some way towards the nil level hypothetically indicated. Measures such as screening out atopic workers, and removing from exposure those who develop symptoms, combined with using encapsulated material to reduce dustiness, have tended to mask the effects that would have developed had the industry continued to use the enzyme in its original fine-powder form. In addition, too much reliance must not be placed on skin prick-tests to exclude enzyme-related disease. Not only can direct non-allergic effects occur, but I have shown by challenge tests that the material can cause asthma despite negative skin prick-tests(lO). 24o The early fears that the B.subtllis protease might cause direct destructive effects leading to emphysema, had support from the fact that papain, another protease, causes emphysema in experimental animals when administered by aerosol inhalâtion(11) or Intratracheal injection(12). I have mentioned that some of the enzyme-affected patients had developed impairment of gas transfer, sometimes lasting for several weeks after an episode of chest illness but, although this may well have Indicated effects at the small airway, or alveolar level, its recovery made it unlikely that emphysema had been caused. Gandevia, in Australia, reported loss of elastic recoil in some of the enzyme-affected patients(13), which might have been an indication of emphysema, but from more than 100 papers that have followed my initial contribution on this topic, one does not get the impression that the material has been a significant cause of emphysema. That the B.subtilis protease is less likely to cause emphysema that papain has been shown experimentally. In New York, Drs. Goldring, Ratner and Greenberg(13) repeated with the B.subtilis protease the inhalation and intratracheal experiments In hamsters which, with papain, had led to emphysema. It was found that, when B.subtilis protease was administered, some of the animals died from severe haemorrhage into their respiratory tracts but, unlike the animals exposed to papain, those animals which recovered from the Initial haemorrhage did not develop emphysema. Now, as to the problem of the other protease, papain, I have mentioned papain in the context of its capacity to cause emphysema in experimental animals. There is also the consideration of allergy. 241 On theoretical grounds, enzymes as proteins, with large molecular weights, are potential case allergens and, as I was able to show in the of the subtilopeptidase used in detergent enzymes, this allergenic capacity could be independent of its proteolytic capacity. Thus, the inhalation of powdered papain might also be capable of causing sensitisation and respiratory allergic symptoms. Papain has several industrial and commercial uses, two important ones being, in the brewing industry, the treatment of beer so that precipitates are not formed on chilling! and, in the food industry, as a meat tenderiser, either by injection into animals before slaughter, or by treating meat afterwards. There are widely-marketed preparations of "meat tenderiser" for use by the consumer, who is instructed to shake the powder on to the meat before cooking. In recent years, by use of such techniques as spray-drying, papain preparations of high potency in fine-powder form have become available, and with them the increased liability of atmospheric contamination of workplaces where papain is handled, processed, or packed. I had been experimenting with papain solutions during my research into the effects of detergent enzymes and had found that ' the prick-test reactions to the subtilopeptidase were specific, and not shared with other protease such as papain. Consequently, when asked to see a patient who developed asthma while working at a factory where papain was packed as a meat tenderiser, I already knew that, at certain strengths, solutions of papain did not give irritant or other skin prick-test reactions in unexposed control 242 individuals whether or not they were atopic or were sensitised to B.subtilis enzyme. The patient was a warehouse fork-lift truck driver, but in his early time at the factory he had helped in the papain packing room. He developed attacks of asthma for the first time while working at the factory, on one occasion being off work for two weeks. These attacks came while he was working in the warehouse, on the days on which papain meat-tenderiser was being packed in the next room. He gave no history of atopy, confirmed by negative skin prick-test reactions to solutions of common allergens. However, he gave positive prick-test reactions to solutions of papain at strengths 10 times and 100 times weaker than had given no reactions in unexposed control individuals, whether or not they were atopic(15). This supported the likelihood that the death of a young man at another factory, in a severe attack of asthma which developed shortly after a workmate 10 metres away from him had tipped about a kilogram of papain powder into a protein hydrolysis tank, was due to papain allergy. Subsequent investigation at another factory where spraydryed powder was packed for breweries and meat-tenderising firms, revealed that several workers both atopic and non-atopic, from the factory floor, laboratories, and adjacent offices had experienced nasal and asthmatic symptoms following papain handling, and they gave positive prick-test reactions to papain solutions at strengths weaker than gave no reaction in control individuals 243 not exposed to papain. Thus it was confirmed that papain could sensitise and cause allergic illness, a finding that has received support from the work of Tarlo and his colleagues(16 ), who reported positive skin prick-tests, as well as RAST tests for Ige antibody, in their patients. In view of experimental work that has shown that intratracheal or aerosol inhalation of papain can cause emphysema, it was also thought important to find out if there was any evidence of emphysema in these workers. This might well be independent of whether or not the exposed individuals had become sensitised. Consequently I arranged a wide range of lung function tests, chest X-rays and serological tests in addition to tests relating to allergy. It seemed important to include, in the serological tests, assay of o •> -antitrypsin, in view of the vulnerability of homozygotes with very low oí.-antitrypsin levels to emphysema in early lifei believed due to impaired protection against the action on the lung tissue of naturally occurring proteases from and bacteria. leucocytes There was also the possibility that those with inter- mediate low levels - the heterozygotes - might be more than nor- mally vulnerable to the relatively gross exposure to protease from the inhalation of papain powder at work. I am not yet in a position to give full results of this work as the survey is not complete. One factory-floor worker, who had had the heaviest exposure to the high-activity papain powder, showed radiological evidence of large bullae in both upper lung fields and the upper part of the left lower lobe. We have not so far been able to exclude the possibility that this unusual condition was caused by papain, but investigations continue. 244 Fortunately, I think that whether or not it is confirmed that significant proteolytic lung damage can be caused by papain in humans, the safety measures recommended as necessary to pre- vent the allergic hazard(l7) should also suffice to prevent direct effects from the material. 2*5 REFERENCES FLINDT, M.L.H. LANCET (1969) 1, 1177 THORAX (1976) 31, 621 HOW, M.J., Goodwin, B.J.F., Juniper, C.P. & Kinshott, A.E. Clinical Allergy (1978) 8, 347. GELL, P.G.H. and Coombs, R.R.A., in Clinical Aspects of Immunology. Oxford, 1968. PEPYS. J., Longbottom, J.L., Faux, J. Lancet (1969) ¿. 1181 BRITISH MEDICAL JOURNAL (1967) iii, 691 HARGREAVE, F.E., Pepys, J., Longbottom, J.L., Wraith, D.G. Lancet (1966) i_, 445. DOLOVICH, J., Hargreave, F.E., Chalmers, R., Shier, K.J. Gauldie, J., and Bienenstock, J, Journal of Allergy and Clinical Immunology (1973) 52 No. 1, 30. American Conference of Governmental Industrial Hygienists, Documentation of the Threshold^ Limit Values for Substances in Workroom Air¡ Cincinnati, Ohio, 1976. FLINDT,- M.L.H. Revista de Tisiologia y Neumonologfa (1974) 13 No. 1, 115. GOLDRING, I., Greenberg, L., Ratner, I. Archives of Environmental Health (1968) 16, 59. GROSS P., Pfitzer, Emil A., Tolker, E., Babyak, M.A. Karschak, M. Archives of Environmental Health (1965), ii, 50. GANDEVIA, B., Mitchell, C. Medical Journal of Australia (1971) 1, 1031. GOLDRING, I.P., Ratner, I.M. Greenberg, L. Science (1970) 170. 73. FLINDT, M.L.H. Lancet (1978) 1, 430. TARLO, S.M.' Shaikh, W., Bell, B., Cliff, M., Davies, G.M., Dolo.vich, J. and Hargreave, F.E. Clinical Allergy (1978) 8, 207. FLINDT, M.L.H. Proceas Biochemistry (1978) 13 No. 8, 3. 246 Enfermedades pulmonares causadas por enzimas proteolítlcas. M. L. H. Fllndt (Reino Unido) Los trabajadores expuestos a polvos de enzimas proteolfticas procedentes del bacillus subtllls. que se utilizan en la fabricación de polvos biológicos de lavar, pueden provocar asma alérgica« Las reacciones positivas "inmediatas" a la puntura cutánea, a los tests R.A.S.T. para un IgE especffico indican que se están produciendo reacciones de tipo 1 (Gell y Coombs). Las precipitinas encontradas parecían deberse a reacciones proteasas-antiproteasas, y no a reacciones inmonológicas de tipo III, cuya presencia no ha sido establecida en forma certera, pese a reacciones pulmonares demoradas en algunos individuos, y a un pequeño número de reacciones "tardías" a la puntura cutánea. La mayorfa de los individuos afectados se recobran completamente al cesar la exposición, y seoonocen pocos casos de secuelas de larga duración, tales como la fibrosis que puede presentarse a consecuancla de tipo III, o una destrucción del pulmón atrlbulble a efectos proteolítlcos directos. Recientemente se ha podido ver que a veces los trabajadores que manipulan otra enzima proteolítica, la papaína, se sensibilizan y desarrollan asma. En experiencias animales, la papaína causa enfisema, y se están realizando estudios para ver si también puede producirse en los seres humanos. No obstante, los riesgos alergénlcos de la papafna son tales que no se justifica esperar los resultados de esos estudios para tomar enérgicas medidas para Impedir la Inhalación de polvo de papaína. 24? WORK-RELATED DISEASES IN PAKISTAN* (Summary) S.M. Rab, Zakaullah Beg and M. Abu Zafar (Pakistan) The Interaction between man and his work environment may lead to 111 health. Developing countries are becoming Industrial- ised, with the appearance of new chemical, physical and psychosocial hazards. There are also traditional cottage industries where ignorance prevails. A survey showed a substantial number of cases hitherto unsuspected, as followst 1. 21% Incidence of byssinosis in the cotton industry, the largest industry in Pakistan. 2. 40% pneumoconiosis amongst knife grinders and stone crushers. 3. Asbestosis ,in the shipping and motor Industry. 4. 14% barltosis in the barium sulphate mines. 5. Barltosis was found to be the most benign of these. * The paper "in extenso" to be asked to the authors. 249 Enfermedades del trabaio en Pakistan. S. M. Rab, M. Sakaullah y Mohd Abu Zafar (Pakistán) La acción del medio ambiente de trabajo puede llevar al hombre a enfermarse. Los países en desarrollo se van industrializando con lo cual se añaden nuevos riesgos de índole químicat física y psicosocial. También existen las industrias rurales tradicionales donde prevalece la ignorancia, En una encuesta, los autores descubrieron un importante número de casos hasta entonces insospechados t 1. incidencia de 21 por ciento de la bisinosis en la industria del algodón, que es la más grande el Pakistani 2. 40 por ciento de neumoconiosis entre los afiladores de cuchillos y los picapedreros» 3. asbestosis en la Industria naviera y de motorest 4. 14 por ciento de baratosis en las minas de sulfato de bario. De todas ellas la baratosis resultó ser la más benigna. 25o HI/7 UNE MPUVELI E Pf-JFrunocnMTO.SF \ / r r r T A L E LE POI.IHPN or MFFFA rORMEA H. - Fl. PEKKT !.. - r|_ CHARBT P. - PFM KHFOFR A. STLVTfl n. Tnr.hit.ut rlR Pneumn-Phtis.i nlnnie de l'Ariana, Tunisie. Mous avons été frannés "ar la relative fréquence des bronchnoneumopathies chroninues obstructives chez la femme tunisienne ruralR nui ne fume absolument ñas. Notre attention a été retenue par l'existence, chez certaines d'entre elles, d'une habitude particulière : celle de priser, c'està-dire d'aspirer car le nez une poudre de tabac appelée "Neffa". Cette toxicomanie est larqement répandue en milieu rural. De même, elle touche les hommes et est fréquemment retrouvée chez les mineurs (13 % dans une mine de Fe). Un ori'seur (ou priseuse) acharné inhale en moyenne 100 a 300 n de poudre de Neffa par mois ce qui fait 1 a 3Ko par an, traduisent ainsi un véritable emooussiérape. Deux espèces de tabac sont cultivées en Tunisie : Nicotiana tabacum, le tabac a fumer et Nicotiana rustica le tabac a priser. Ce dernier est caractérisé par une teneur importante en nicotine et constitue la matière premiere de base de la Neffa. MATERIEL FT METHODES: Le travail a été fait a l'institut de Pneumo-phtisinlnpie de l'Ariana avec la collaboration du laboratoire de l'Institut d'Hvniene et de Santé Pub.linii" de Clu.i - Roumanie, Le nombre de cas observés depuis J974 dépasse la centaine. Notre étude actuelle norte sur PO dossiers. 251 "ti s'anit i;n n(5n*r-il H» ruraux, en majority dRS fnromos - 37 femmqg - snit 61 "* du total — 23 hommes — snit 39 ,p' du total t.'ane moyen de nos malades sç situe environ de 5Í3 ans (57,? pour 1 R S femmes at Fin,7 pour 1 R S homn-es. La duri™ ri * i r nrimation tabanique est dn 23 ans pour 1 R S fpmmes et dp 31 nos nour 1 R S hommes. nnnnrrc; rLTMTcn-RflnTni.pni^iiE : a - Mode de recrutement : les malades ont Ät<5 hospitalisés onur des raisons diverses Tableau 1; l»10TTF D'HOSPITALISATION Nombre Pourcentaoe Hfimontsie 20 cas 33,3 însufisance Respiratoire 14 cas 23,3 CflHSF. 9 cas 15 Raisons diverses (Silicose, Tuberculose, Min,etc.) 9 cas 15 Pneumopathie banale 8 cos 13 Bronchite Chronique T P T n L 60 ras 252 ion % ! CI inique : Sur le plan clinique, es sont les phénomènes des bronchopneumopathies chroniques qui dominent dans la majorité des can. L'hémoptysie, en nénéral de petite importance, est presento daps 1/.3 des cas suivie de | 'insuffisance respiratoire dans 1/4 des cas. fl l'examen objectif, on retient une triade caractéristique : - un facies tabanique a divers degrés - une distension thoracique a divers daqrés - une altération de l'état général plus ou moins marquée avec amaiqrissement notable. Cette triade clinique evocatrice est plus fréquente chez les femmes (78,3 %) que chez les hommes (65,2$). L'auscultation révèle la présence des raies bronohiques a prédominance de sibilanta dans 71,6 % des cas. Le.retentissement cardiaque a type de tachycardie sinusale et d'hépatoméqalie est retrouvé dans 43,2 % des cas pour les femmes et de 26 % pour les hommes. Radiologie : Sur le plan radiolooique, on constate au début une réticulomicronodulation intéressant la moitié inférieure des deux poumons. A un stadR plus avancé, l'image réticulomicro-nodulaire peut intéresser même la totalité des deux poumons respectant dans une certaine mesure les ommets. 253 A un starla ultime (la starlo de compi i cations ), nn observe en plus, sur un Fond emphysémateux des imanes fibrokystiques (en nid d'abeilles) essentiellement au niveau de la moitié inférieure das poumons. Les premieres anomalies radioloqiques apparaissent après 10 a 15 ans de tabagisme (prise de Neffa). d -fliolonie: A l'examen de laboratoire de routine, on note simplement une Uw 3» moyenne élevée qui se situe a 47 mm/h. e - L'Exploration fonctionnelle : Elle montre une perturbation de type obstructif importante dans la majorité des cas (Tiffeneau 60 %). f - La bronchoscopie pratiquée dans la plupart de cas décrit un aspect inflammatoire particulier (rouoe framboise),une hypersécrétion, une fragilité excessive de la muqueuse qui saione au moindre contact du bronchoscope. L'ANALYSE DE LA POUDRE DE MEFFA : Ellea mis en évidence la présenco ds silice libre (SICU) en proportion de 2,8 % et aussi en quantité semblable du Ca,Al et Fe. Le taux de nicotine de Meffa tunisienne varie entre 2% et 2,B %. La nranulométrie donne les résultats suivants : - 66 % des particules ont un diamètre inférieur a 3Wm. - 10 •' inférieurs a 9 Um. - 24 )', supérieurs a 10 (Um. rione la majorité des particules peuvent penetrar jusqu'au fond des alvéoles plumonaires. 254 FXPFRjFfirrs sin nrs ArJIIWIX DF LARPRATOIRF: I'PS nxneriencep ont été faites nur ries souris blanches d'un nnids movrn dn IST a 2P0 n. La voie transtranhéable a été utilisée pniir Rnnniiss.i érnr les animaux. Une dosn do F¡0 mo de nnudre nar animal dans l ml de sérum physiolonique a iti administran a un premier lot de AO animaux. flores un mois, ? seulement ont survécu. Les lésinns anatomn-patholoniques observées sur les animaux sacrifiés sont d'un typB tres particulier : "Pneumopathie nodulaire oranulomateuse oinantncellu.la.ire a corps étranqer". Une réaction fibreuse peri-focale et une infiltration lymphocvtaire ont été observées.(V.V. Paoillian). Suivant la même méthode une deuxième 9érie d'expériences (sur 7P animaux) a été faite. Deux lots d'animaux sont empotis- siérés a des doses de 10 et de 5 mn et un 3ème lot témoin est installé avec du serum physiolonique (lml). Les résultats histopatholopiques et biochimiques obtenus après 4 mois de survie sont les suivants: Les composants biochimiques du parenchyme pulmonaire ne subissent aucune mndification significative, y compris le surfactant alvéolaire. Fn revanche, on note une nette diminution du nombre des macronhanes nar rapport au lot témoin avec altération importante de leur viabilité a la dose de 10 mo. L'examen macroscopique ohiactive une dissémination nodulaire narench"Piateuse, L'histopatholoni.p montre divers asoects: - rarement des nndules lvmohocvtaires interstitiels; - fréquemment des nndules avec cellules qéantes rote- • nant un matériel amorphe éosinoohyle et entourés des 1vmphocytes; 255 - des nodules encapsulés par uno fibrose; - ries nodules fibreux. Ces asnects sont la traduction histopatholonique d'un même processus a divers stades évolutifs. EXAMEN ANnTOWn-PflTHClLnninilE : Une étude anatomopatholooique a été faite sur du matériel humain prélevé soit par biopsie bronchique (2 cas),soit par biopsie pulmonaire (4 cas). Les fragments bronchiques montrent: "une fragmentation intense et une dégénérescence oedémateuse et fibrinoide du tissu conjonctif sous-épithélial et en particulier des fibres élastiques" (M. KAP10UN). Les biopsies pulmonaires (4 cas) montrent une architecture pulmonaire profondement remaniée lesquelles Intéressent essentiellement les alvéoles, les cloisons inter-alvéolaires, les bronchioles et les petits vaisseaux. Les fragments pulmonaires des 4 malades biopsies ont été respectivement examinés par trois laboratoires différents l?.r cas : Y.B. 63 ans hospitalisé pour bronchite chronique, hémoptysie, lésions réticulo-micro-nodulaires. Habitudes : priseur rie Meffa a raison rie paquet(lOn) pour 2 à 3 jours depuis 25 ans.Riopsie pulmonaire le 26.7.76. Histo : 10.9.63 Biopsie nulmonaire (linnula) montrant un certain degré d'anthracose orincipalement autour ries arteriole Par ailleurs, les cloisons inter-alvéolaires sont so vnnt le sienn d'une hystinn»tnsR 1RS épaississant ri' facon inénale., constituant des aman col lui aires rie taille variable, réduisant parfois considêra'ulenent la lumière des alvéoles. 256 In cvtoolasme da ces hi stincvtes Bst tatoué d'un pinment brun. Dans certaines D I S H G S ces histiocytes s'allonoent nour prendre un aspect f ihrnh.lastinue. Peaucouo plus rarement, ces histiocytes semblent occuper la lumiere des alvéoles (pr.A.Chedly Tunis), 2eJT8 caá L.A.«, 65 ans, hospitalisée a plusieurs reprises pour bronchite chronique obstructive. Dernièrement, l'imane radinlogique évonue une collanénose (réticulomicronodulation). Habitudes : priseuse de Meffa depuis 30 ans environ a raison d'un paquet (lOn) par 3 jours. Avril 1976, Biopsie pulmonaire (O.PITERS) Protocole hintopatholonioue: -La préparation histopathologique comporta 3 tranches da parenchyme pulmonaire fortement remanié présentant uns lobulation tràs accentuée. Les lobules .pulmonaires contenant des bronches dont la lumiere élarnie a un contour festonné irrénulier. La plupart de ces brennhes sont libres; quelques-unes sont toutefois remplies de mucus; leur muqueuse est tapissée par un epithelium cylindrique cilié relativement haut ppurvu de quelques cellules mucipares. Les bronchioles ont une lumiere encore plus irréauliere et leur epithelium de recouvrement est localement métaplasique. Dans la lumiere, pn observe souvent du mucus et des histiocytes tandis que dans leur paroi existe un infiltrat lymphocytaire avec des amas lymphoides au niveau du parenchyme alvéolaire. La structure pulmonaire est peu reconnaissable. Les al- vénles sont souvent bordées d'un epithelium cubo-cylindrique; leurs lumières rarement libres contiennent des histiocytes dont le cytoplasme a un aspect spumeux. Les septas alvéolaires cen- sidérablement épaissis par de la fibrose sont parsemés de cellules inflammatoires a prédominance lymphocytaire et plasmocytaire einsi que d'histypeytes alareis de oranulation de pous- siere noire non cristalli nés nt part5.cul.es biréf rinrentes (Prt F. P^FRSSmnn - Univ. dn Louvain). 257 - 3ome Cas : Z.B.A, : 67 ans, hronchite chronique depuis 7 ans \ predominance hivernale. Dennis un an, expectoration mucopurulente avec quelques himnptysias. A la rariin, imanes réticulo-micro-noriiilaires, fibrokystiques au niueau des bases. Habitudes : Priseuse de Neffa a raison d'un paquet (lOq)tous les deux jours, nu 3. Le 8 novembre, 1977, biopsie pulmonaire. Compte rendu histopatholoqique. Description: Aspect de fibrn-nranulnmatnse pulmonaire tres organisée avec bronchiolectasies micro-micro-kystiques,tres nombreux dépots anthracoldes biréfringents parsemant le prélèvement, images d'anqoite des arterioles pré-capillaires et de moyen calibre, microgranulomes avec assez nombreux plasmocytes. L'ensemble peut faire évoquer des phénomènes d'hypersensibilité au sens le plus larqe du terme, mais le fait dominant est l'existence d'un empoussiéraqe majeur par de nombreux dépots biréfringents (Pr. 3. CHRETIEN et Dr. L. DANEL - Hôpital Laennec,Paris). - 4eme Cas : ß.S..., 41 ans, ouvrier de fond (charqeur) dans une mine de phosphates pendant fi ans. Depuis 8 mois, travaille au jour. A la suite d'un depistane radio-photo au mois de mai 1977, on constate : image réticuln-micro-nodulaire du tiers inférieur des deux poumons avec anomalie Hu diaphragme droit (imane en brioche correspondant a un kyste hydatique rlu foie extrait par thoraco-phréno-lanaratnmie droite le 2 Janvier 1978). Habitudes : Hon fumeur, mais il nrise de la Meffa a raison d'un paquet (10 o) tous les deux a trois iours depuis 20 ans. Biopsie pulmonaire droite. 258 "Fn conclusion: fihrnse pulmonaire debutante ause bronchectnsiRs micro-kystiques et tres nombreux dépots anthracoides contenant quelques rares particules biréfrinnentes tatouant le prélèvement, associées a des imanes d'endartérito fihrousfî des arterioles précapillaires avec dédoublement dans certaines zones des limitantes élastiques internes". (Pr. .1. CHRETIEN et Dr.. Cl. DftUEL - Hôpital Laennec - Paris). CONCLUSIONS : Jusqu'à nos jours, le neste de priser est considérer anodin par l'ensemble de la population. La Neffa prend memo le relais de la cinarette chez les orands fumeurs (moyen de sevraoe souvent pratiqué). CettB toxicomanie est largement répandue en Tunisie, mais aussi dans toute l'Afriqua du Nord. La patholoqie induits par la Neffa se présente cliniquement comme une bronchopneumopathie chronique obstructive apparemment banale. Par contre, l'aspect radiolopique dans les cas typiques est celui d'une pneumoconiose. tardive. Son apparition est relativement Elle entraîne un remaniement de l'architecture pulmo- naire a la rone d'échanne avec toutes les conséquences fonctionnelles. Quand ce type de tabanisme touche les mineurs, cela ne fait qu'intrinuer et compliquer la patholnnie professionnelle. 259 Mous pensons que cette nouvelle entità fit innathn^ínique ORut se ranner parmi 1er; pneumoconioses x/n'oßtales. L'appellation "poumon de Meffa" nous semble justifia. Nos remerciements au Docteur GUY PIETERS qui nous a airie dans ce travail. f nt'i-Clés : Tabac a priser "floffa" - Pneumncnni nsp. vanitalo Pnumnn de rief fa. (Key-unrds). 26o flTnl i M'ÍTí'PHir 1) BOUSQUET J. - GAÏRAUD J. P. '" MICHEL F.B. : *^ "Physiopathologie des alvéolites allergiques Poumon et Coeur - Tome XXXIV - N" 2, 1978 p. extrinsèques". 157-169 2) CHRETIEN .T. "L'appareil respiratoire face aux nuisances de l'environnement" La NouV. Presse Med. Nov. 76, 5, N" 40, p . 2687-83 3) CBRETIEN .T: : "Un objectif prioritaire La Nouv. Presse Med., 4) CHRETIEN J. c la lutte contre le tabagisme". 11 Dec. 76, S, N" 42, p. 2851-52. ; "Les risques aéro-écologiques" Les Act. Pharmac. T N" 332 - fivr. 1977. p. 19-25. 5) CORNEA ff. - EL MEKXI L. ~ EL ÇHARBI B. - BEN KHEDER A, et SILVIA QfiBOR "Poumon de Neffa" (Une Pnenmoconiose Tunisie Méd. N" 3 Mai-Juin 76. 6) MAIER A, - BMTZENSQHLAGEB. A.-.et Végétale ?). S.. ORION : "Thrombarthériopathie pulmonaire professionnelles de poussières Arch. Mal. Profes. -Med. Trav, allergique au cours d'Inhalations organiques". et Sociale - 1974 T. 35 N" 10-11 p. 875 7) POPA 7. - GAVRILESCU N. - PREDA ff. - TECVLESCV D. - PLECIAS M. et CIHSTEA M. "Etude de l'allergie dans la byssinose : sensibilisation de coton, de chanvre, de lin et de jute" Brit, J. Industr. Med. av. 1969, 26, 101-108.. 261 aux antigênes Una nueva neumoconíosis vegetal. El pulmón de Neffa. G. Cornea, L. El Mekkl, B. El Gharbl, A. Ben Kheder y S. Gabor (Túnez) Se trata de una neumoconíosis observada en Túnez y provocada por la aspiración por la nariz de un polvo de tabaco llamado "NEFFA". Este tipo de tabaquismo se encuentra muy generalizado en el medio rural y sobre todo entre las mujeres. Afecta también a los menores (13 por ciento en una mina de hierro), agredidos ya por otros polvos. El adicto Inhala entre 109 y 300 gramos de polvo de NEFFA por mes, lo que representa de 1 a 3 kilos por año - un verdadero empolvamiento. En la mayorfa de los casos, el cuadro clfnico se caracteriza por fenómenos de bronquitis crónica obstructiva con todas las consecuencias funcionales (enfisema, insuficiencia respiratoria, trastornos de transferencia, etc.). En el plano radiológico, se observa al principio una reticulomicronodulación que interesa la mitad inferior de los dos pulmones. En una fase más avanzada, la Imagen reticulomicronodular puede llegar a interesar la totalidad de los dos pulmones, salvo en cierta medida las vértices. En la fase final (fase de complicaciones) se observan además, sobre un fondo enfisematoso, imágenes fibroqufsticas (imagen en nidos de abejas), principalmente a nivel de la mitad inferior de los pulmones. Las primeras imágenes radiológicas aparecen tras un período de tabaquismo (Inhalación de NEFFA) de 10 a 15 años. El análisis de este polvo ha puesto en evidencia la presencia de Si0 2 (sílice) libre con una concentración de 2,8 por ciento y también, en cantidades análogas, de Ca, Al y Fe. La granulometria da los siguientes resultados i el 66 por ciento de las partículas tienen un diámetro inferior a 3 micrones; el 10 por ciento, inferior a 10 micrones, y el 24 por ciento, superior a 10 micrones. Por consiguiente, la mayoría de las partpiculas pueden penetrar hasta el fondo de los alvéolos pulmonares. Las experiencias efectuadas con animales de laboratorio 262 (empolvados por^vía intracraqueal a una dosis de 50 mg en sérum fisiológico) muestran lesiones de un tipo Darticular "neumopatía nodular granulomatosa gigantocelular con cuerpos extraños. Se han observado una reacción fibrosa perifocal y una infiltración linfocitosa". Las biopsias pulmonares hechas a personas enfermas (cuatro casos) muestran una arquitectura pulmonar profundamente modificada, en lo tocante sobre todo a los alvéolos, las paredes interalveolares, los bronquiolos y los pequeños vasos sanguíneos (angeitis de las arteriolas precapilares y de calibre medio). Se produce un espesamiento de los tabiques, infiltrados por montones de histiocitos cuyo citoplasma está inundado de un pigmento negro no cristalino y de raras partículas cristalinas birrefringentes. El hábito del NEFFA se halla muy generalizado en Túnez, pero también en todo el Norte de Africa; cuando este tipo de tabaquismo afecta a los menores, la patología profesional se complica. 263 I N D I C E S E S S I O N IV 5.H, 7aldi .. Recent proqress in etiopathogene9Ì9 of Pneumoconioses Tatsuo Sano and Isamu Ebihara Considerations on pathology, pathogenesis and etiology of pneumoconiosis. I.Le Bouffant., H.Daniel., J.C.Martin Nocivité variable des poussières de silice selon leur origine. Influence de certains minéraux Quinot t., d'accompaqnememt Cavelier C , Ulerearon m.O. Chimie de surface et cytôtôxiclte de la Silice. W.Uleller. New aspects in the etlopathogenBSÌ9 of silicotic and anthracosilicotic lesions Hisato Hayashi. Nineralogical analysis of lung dusts in pneumoconiosis with an analytical electron microscope. 265 RECENT PROGRESS IN ETIOPATHOGENESIS OF PNEUMOCONIOSES S.H. Zaidi (India) Industrial Toxicology Research Centre Lucknow - India One of the earliest reports on the etiopathology of the miners lung was made by Agricola (1494 - 1555) who mentioned ulceration of the wind pipe due to dust inhalation. Ramazzini (Padua 1700) later described in detail the pathology of the miners' lung and commented "when the bodies of such workers are dissected the lungs are found to be stuffed with small stones". Greenhow (1865) observed drifts and deposits of sand in the lung tissue and from the lungs of one worker he isolated about 30 grammes of this so-called sand. A year later Zenker gave a detailed description of the pathology of the lung due to inhalation of iron dust. The autopsy showed "a brick-red pigmentation so intense that all blood and tissue colouring was almost entirely obscured Several large cavities and numerous firm fibrous nodules were scattered throughout both lungs", and these lungs contained a total of 22 grammes of iron oxide. Some pieces of lung specimen obtained from Prof. Zenker by Dr. Greenhow are still preserved in the Middlesex hospital( London. Earlier Craig (1834) evolved the technique of large tissue sections of miners' lung. He wrote "the best manner of ascertain- ing the exact situation of the black matter in such cases is by inflating the lung-slightly, drying it thoroughly, and then cutting it into slices in various directions be distinctly seen i the air cells can the exact situation of the black matter 267 may easily be ascertained." In recent times this technique has created much interest and the large tissue section technique contributed by Gough and Wentworth (1948) has helped in the study of pathology of miners' disease. The end of the nineteenth cen- tury, however, saw unanimous agreement that lung disease of the miners was due to the inhalation of dust and that dusty lung was more prone to tuberculosis. Another approach to the study of the etiopathology of miners disease is experimental pathology. The research of Claude Bernard (1887) is perhaps the first of great significance in the field of experimental pneumoconiosis. Bernard tied a bladder containing sufficiently large quantities of coal dust around the neck of rabbits. With each movement the dust stirred up and rabbits breathed the dust cloud. At the end of several days, no black pigmentation was seen in the lungs. The failure of Bernard's experiments could be attributed obviously to the limitations of his technique. At the same time Arnold (1885) evolved a technique in which he blew air through a tube or hopper of dust which was vibrated or stirred, over a period extending to 10 years to rabbits and dogs. He succeeded in producing lesions which consisted of dust deposits in the alveoli and lymph nodes. This technique has formed the basis of present day dusting techniques in the field of experimental pneumoconioses. The world-wide industrial revolution of the present century frequently made work in dusty atmospheres unavoidable, so extensive experimental studies on the problem of pneumoconiosis have been undertaken. Now highly sophisticated dust chambers in which dust clouds, temperature and humidity can be controlled are available to 268 the scientist for work in the field of occupational health. SILICOSIS Recent research has put at our command a vast body of facts concerning the pathogenesis of silicosis, but there are still many hiatuses in our knowledge. Although attempts to produce experimen- tal silicotic nodules have been successful, we still do not know precisely the manner in which the human lesions develop. This has given rise to over fifty theories which are based on physical, chemical and biological principles. The earliest physical theory was put forward by Zenkerk (1866) who postulated that it was the sharp and angular edges of quartz particles which produced fibrosis in the lung. Heffernan (1953) advanced the hypothesis that freshly fractured silica particles had unsatisfied valencies on their surfaces which were reactive and directly responsible for biological action. The piezo-electric effect was propagated by Velicogna (1946) and later by Evans (1948). They showed that fibrosis was produced because of piezo-electric properties of dust. A negative charge theory was initiated by Hounan (1952, 1954) who thought that silica particles were pathogenic due to the presence of negative charge on the surface inciting interaction between the positive charged protoplasm of the cell. The crystallinity theory was put forward by King (1953) and later it was shown by Zaidi et al (1956) that there was a relationship between the crystallinity of silica and fibrogenecity because fused silica was least fibrogenic while quartz, cristobalite and tridymite in that order were increasingly more fibrogenic. Such relationship has not been established in man. 269 Scheel et al (1954) put forward the surface absorption theory that quartz absorbs protein. The theory of critical particle size was also put forward by King (1953) and later by Zaidi et al (1956), who determined the most pathogenic particle size of silica dust. Research on human silicosis and extensive experimental investigations have pointed out that there is a range of maximally fibrogenic particle sizes. The probable upper limit of pathogenic particle size is 10 microns (although many believe it to be about five microns) and the lower limit of pathogenic particle size is probably 0.002 micron. All the dust particles found in silicotic lungs are less than 2 micron in diameter, and most are less than one microni overwhelming experimental evidence supports clinical findings that the optimum size of the silica particles (the size which is most pathogenic) is in that range. ly been emphasized by Vitums et al (1977). This aspect has recentThe significance of animal experiments and human autopsy findings for studies of the fibrogenic activity of a particular particle size in man in still open for further investigation. The chemical theories are based on the hypothesis that chemical interaction between silica and the tissue occurs. The solubility theory was described by Kettle (1926, 1934) and King and Belts (1938). On the basis of animal experiments they observed that the fine particles of stone dust which get into the lungs were pathogenic because silicic acid dissolved out from their surface. Further the pathogenicity of any stone dust was related to the rate at which it released silicic acid into the solution. Holt (1957) observed that in the cytoplasm of quartz-laden phagocytes a collagen precursor was formed, which had the ability to 27o collect the monosllicic acid as It was liberated from the surface of the particles and to store it so that this acid could polymerise and act as a factor which would change procollagen to collagen. This modified silica solubility theory gives only an outline of the process of silicosis and suggests that the basic solubility theory can still be taken as a guide for further experiments on the problem of silicosis. Other chemical theories include the sericite theory of Jones (1933), Edge (1934) theory of microinclusions of liquid carbon dioxide in quartz, formation of alkali as a result of hydrolysis of mineral silicates by Briscoe (1936), and the theory of Holzapfel (1942, 1949) that fibrogenesis depended on the acid« acidity of silicic The view of "mineral shift" of Schepers (1960) related to the silicotic process still needs clarification. Thomas (1965) has shown that contact of the cell with SiO, tetrahydron groups and transferable groups attached to them is a prerequisite for fibrogenic action. Brieger and Gross (1966,1967 a,b) further confirmed this hypothesis and suggested that the structure, and not the dissolution of silica, was of significance in the production of fibrosis. Vigliani et al (1950) suggested an immunological hypothesis for silicosis based on the observation that in patients there was an increase of gamma globulin and since antibodies belong mostly to the gamma globulin fractioni the increase may be an expression of antibody production. It was suggested that, if silicosis has an immunological pathogenesis, the free silica may provoke or increase 271 the formation of antigens and subsequently of antibodies. Silica may also act as a booster of heteroantigens or liberate autoantigens directly by killing a comparatively large number of cells. This work from the laboratory of Vigliani formed the basis for further investigations which have been reviewed by Zaidi (1969). Evidence was also collected showing that the immunological hypothesis does not satisfy several of the criteria required for a disease on an established immunological basis. Klosterkötter (1955) found that the increase in gamma globulins in silicosis is a nonspecific reaction. Antweiler and Hirsch (1956) while doing animal experiments on the formation of antibodies in the development of silicosis could not get encouraging results. and Voisin Collet et al (1961) et al (1964) also observed that silica does not act as an antigen. Licht (1960) found that the hyaline substances of the silicotic nodule were devoid of any antigen. According to Vigliani and Pernis (1962) "the final observation is that silicosis is not an immunological disease but a disease with strong immunological components. The immunological phenomena of silicosis do not develop from a specific antigen produced by quartz but they consist of accumulation, in the developing silicotic nodule, of many antigens unknown at present, and in their ability to stimulate locally the production of the corresponding antibodies by the adjuvant action of the quartz". The immunolo- gical hypothesis outlined needs more precise verification, chiefly with regard to the possible mechanism or the formation of autoantigens capable of inducing active production of autoantibodies. 272 Recent research has again shown a shift in favour of a basis of immunological hypothesis of silicosis. Immunological response is associated with lymphocytes, one population of which, known as T-lymphocytes, is stimulated to maturation by the thymus and the other, B-lymphocytes, has its origin in bone marrow. The cellular immunity which is T-cell dependent has assumed great significance in regard to lymph nodes and the respiratory tissue. Two groups of workers, Nash and Hoil (1973) and Kaltreider and Salmon (1973), have shown that both T and B cell systems of the lung are capable of being stimulated when an antigen comes in contact with the respiratory tissue through inhalation« In the light of these recent findings the immune response of the lung due to contact with antigen presents a fruitful field for further research. Electron miscroscopic studies have been made on the fate of silica particles after inhalation which have given useful information on the pathogenesis of silicosis. Pernis et al(1960) and Allison (1967) have demonstrated that the silica particles were first engulfed by phagocytes and taken up into phagosomes which then fused with, lysosomes to form phagolysosomes. The particles chemically damaged the membrane of phagolysosomes and the hydrolytic enzymes were released into the cytoplasm. became rounded due to the tually died. The phagocytes action of hydrolytic enzymes and even- Schlipkötter (1955) suggested that inactivation of the particles of cytoplasm led to the lack of function of the cells. Further, Schlipkötter and Linder (1959) observed, after nine months of intratracheal injection of quartz in to rats, concentric lamellated membranous structures in the nodule which later led to the initiation of the fibrotic process. 273 Similar detailed studies of the interaction of silica particles and the cytoplasm of macrophages have since been extensively reported. ASBESTOSIS Asbestos which is a magnesium silicate, has been mined and its fiber made into fire resistant linen several centuries before Christ. Today, in industry asbestos is a mineral of a thousand uses like heat-resistant insulators, cements, furnace and hot pipe coverings, filter medium, fire-proofing gloves, clothing and brake lining. Since the comprehensive report of Merewether and Price (1931) it has been established that asbestos dust is harmful per se and causes asbetosis among asbestos workers who have a high morbidity and mortality (Elmes et al 1976i and Peto et al 1977). are in progress in many parts of the world. Studies on this aspect The chemical, physio- chemical and biological properties of asbestos have been reviewed by Warwick (1973), Lewinsohn (1974), Harington et al (1975) and Snyder (1977), and pathology described by Meyer (1976). The follow- ing are some of the recent views on the pathogenesis of asbestosisi 1. Interstitial fibrosis of the lung (asbestosis)i Two views on the mode of development of asbestosis have_ been put forward. Accordi ing to one, asbestosis is a chemical process and according to the other it is a mechanical effect of the asbestos particles. Recently an immunological basis for asbestosis has also been described. The problem of particle size in relation to fibrosis is still open for further investigations. However, particles of less than 5 micron diameter are supposed to be harmless (Gross,1977). The current knowledge will be advanced if more experiments are designed to investigate the role of the size and shape of asbestos dust in relation to fibrosis. Hammond and Selikoff (1973) have observed that radiologically evident pulmonary fibrosis is also enhanced by 274 cigarette smoking. 2. Asbestos bodies: These bodies are formed because of the in- corporation on the fibers of a protein layer containing iron. They are also known as ferruginous bodies. The formation of asbestos bodies has been reviewed by Das et al (1978). They may also be found in the lungs of the population which is not exposed to asbestos, but in workers handling asbestos they are found in large quantities (Doniach et al 1975). It is now possible to characterise and differentiate asbestos fibers from other bodies by electron diffraction and electron probe microanalysis (Berry et al 1976¡ Langer et al 1973¡ Auerbach et al 1977). 3. Heural plaques i The pleural plaques are formed due to the thickening of pleura which often gets calcified, and occasionally there is hyalinisation. Their formation has been attributed to asbestos inhalation as well as to other previous pleural diseases (British Thorax and Tuberculosis Assoc, and N.R.C. Pneumoconiosis Unit, 19721 Navratil and Trippe 1972; Navratil and Dobias 1973¡ and Yazicioglu 1976). 4. Lung caneen Increasing incidence of lung cancer has been re- ported in asbestos workers (Doll, 1955; and Buchman, 1963). The cause of the cancer so far is unknown, but its occurrence is affected by factors like inheritance, race and co-factors like cigarette smoking (Selikoff et al, 1968). Although the latent period for the development of cancer may be many years, its appearance in the lung is detected at a comparatively late stage when treatment is not very effective. 5. Gastrointestinal and laryngeal tumoursi Asbestos has been suspected to cause an increase in the incidence of these tumours 275 (Enterllne and Henderson, 1973, and Stell and McGill, 1973). A relationship between asbestos, smoking and laryngeal cancer has also been described (Shettigara and Morgan, 1975; Saracci, 1977 and Gross, 1977). 6. Diffuse mesotheliomai Wagner et al (1960) reported the asso- ciation of mesothelioma with asbestos workers, and subsequent reports have shown that it is associated with the crocidolite variety or a mixture of different kinds of asbestos dusts« Only a few fatal cases of mesothelioma have been reported from amosite and none in antophyllite asbestos mining. pleura and in the abbomen. These tumours occur both in the The etiology of mesothelioma due to inhalation of asbestos fibers still remains uncertain. Animal ex- periments with asbestos inhalation exposure or intratracheal injection have not led to the development of mesothelioma. Wagner et al (1969) demonstrated that it was intrapleural injection alone which gave rise to the formation of this type of tumour. No association has been demonstrated between cigarette smoking and mesothelioma. Harington (1965) demonstrated that tumours developed both with untreated asbestos and the samples from which hydrocarbons were extracted. He suggested that a critical proportion of Ferric (Fe ) +2 and Ferrous (Fe ) forms of iron in the fiber may be carcinogenic. Experiments from Gross's laboratory indicate that contamination by nickel or the chrysotile dust during the hammering process produced lung cancer in rats exposed to high concentration of that dust (Gross et al, 1967). Animal experiments designed so far to test the importance of waxes and oils as contributory factors in the production of mesothelioma have shown these contaminants unlikely to be relevant, also there were no good clues suggesting that trace 276 elements were likely to be a major factor In the production of asbestos cancer (I.A.R.C, 1973). The question of the significance of structure therefore assumes more importance than the physiochemical properties. According to Gross (1977) lung cancer developed only in those asbestos workers who were heavily exposed to this dust, and he suggested that there was a dose-response relationship between the dust exposure and disease. Efforts should therefore be made to restrict the use of asbestos by substitution and imposing restrictions under which asbestos is processed. SILICATE PNEUMOCONIOSES In recent years, the harmfulness of the inhaled silicate dusts like talc, fiber glass, kaolin has been recognised. The pneumoco- niosis caused by silicate is termed "silicatosis". Talcosls Pneumoconiosis caused by the inhalation of talc dust has been called "talcosis". In their review on talcosisf Alivisatos et al (1955) observed that the disease is a definite clinical entity, a type of "Fibrotic pneumoconiosis accompanied by functional disturbances". In New York disabling pneumoconiosis from talc has been reported in 14,5 percent of the workers exposed (Hunter 1964),. Messite et al (1960) pointed out that workers exposed to both fibrous and non fibrous varieties of talc suffered from pulmonary fibrosis. Italian workers are, however, of the opinion that the inhalation of pure talc does not bring about significant pulmonary fibrotic lesions even if inhaled over a long period (Scansetti et 277 al, 1963| Tronzano et al, 1963; Ghemi et al, 1963; Rubino et al, 1963; Pettinati et al, 1964, and Dettori et al, 1964), but Rubino et al (1976) has recently described mortality in talc miners. McLaughlin et al (1949) who described the first case of talcosis concluded that "without doubt the fibrosis in the lung was associated with the presence of the particles of talc dust". Later Biasi (1937) noted the absence of quartz in the lung while Hunt (1956) showed less than 0.5 percent quartz in the lung residue in cases of talcosis. Schepers and Durkan (1955) described the fundamental pulmonary talc reaction, which was comprised of multiple irregular shaped foci 1-3 mm in diameter consisting of macrophages arranged in a stellate manner around medium-sized and smaller blood vessels. Seeler et al (1959) and Kleinfeld et al (1963) noted diffuse pulmonary fibrosis, cystic spaces, and asbestos-like bodies in talcosis. Experimental studies have also shown that the initial reaction to talc dust in various tissues of different laboratory animals is mild (Zaidi, 1969). Schepers and Durkan (1955) and Luechtrath and Schmidt (1959) observed that the divergent reports on the fibrogenic activity of talc dust were due to impurity in the talc. Lords (1978) who has, however, extensively reviewed the available literature on talc, concluded that with talc there is a fibrotic response which is dependent on the dose administered, and certain levels of are tolerable. exposures Although no neoplasia has been observed with talc inhalation, it may be suggested that the fibrous contents of talc may pose a possible occupational carcinogenic hazard, and an open mind has to be maintained on the matter (Blejer et al, 1973). 278 Fiber Glass Glass in the form of the fine fibers is used in increasing quantities in industry. During preparation of "fiber glass" very small glass fibers are released into the air and the atmosphere may shimmer with them. Roche (1946) observed that glass wool "fiber glass" did not cause any pulmonary fibrosis which was confirmed by Dhers et al (1946). Kahlau (1947) noted occasional cases in which the inhalation of glass wool dust was claimed to be a contributing cause of pulmonary disease. Barsi (1964 a,b) noted prevalence of chronic bronchitis and Murphy (1961) described haemorrhagic bronchitis. Pushkina (1965) observed exudative and inflammatory response in the lung following glass wool inhalation. Post-mortem studies on workers exposed to dust for long periods however failed to demonstrate any pathological lesions (Gross et al, 1971). Gardner (1942) observed that glass wool lacked the basic physiochemical properties that would produce fibrosis. Schepers and Delhant (1955) showed that inhalation experiments produce only focal areas of dust collection but when introduced intratracheally into guinea pigs, 20 to 50 micron fibers provoked well defined fibrosis. In inhalation experiments short glass fibers of 6 micron and less in length produced bronchial epithelioma hyperplasia. This has been questioned by Gross et al (1960) on the basis that spontaneous bronchial hyperplasia also occurs frequently in stock animals. Gross et al (1960) studied the biological effects of coarse glass dust (50-400 micron) and noted the laying down of a few delicate collagen fibers. The lung reaction to fine glass dust (1.1 micron) both in rats and guinea pigs for a period of one year, consisted only of focal collections of alveolar dust cells without fibrosis. Further inhalation studies conducted by Gross et al (1974) with glass dust of average length of 10 micron in two species 279 also resulted only in macrophage reaction and no tumours were seen. Kushner (1974) observed, by using intratracheal route instead of inhalation, that longer glass fibers of 20 micron length were associated with fibrosis of septal wall. This data indicated that it was the long fibers which may cause fibrosis. In recent years, however, the animal experiments of Stanton and Wrench (1972) and Wagner et al (1973) have indicated that, when glass fibers or fibers of aluminium silicate of 0.5 micron diameter or less and of a length of 10 to 20 micron or longer were injected by the intrapleural route to rats, there was development of tumours. The experimental finding assumes significance in terms of the hypothesis that these fibers when inhaled may also cause tumours in man. Gross et al (1977) observed that the dose of mineral fibers used in these experiments was high and the animal species inappropriate. Nonfibrous and non-carcinogenic dust, e.g. barium sulphate or solids such as plastic fibers, glass particles, cholesterol crystals, also produce sarcomas but at a much lower incidence. The extrapolation to man of carcinogenesis induced by fibers in rats therefore appeared unwarranted. Kaolin Pneumoconiosis produced by kaolin is known as kaolinosis. Recent references to industrial hazards arising from the inhalation of kaolin have been concerned with the pottery, ceramics and refractory industries where kaolin is used in admixture with other mineral powders, notably felspar and flint. Lynch and Mclver (1954) described that, in an autopsy on two cases of kaolinosis, nodular fibrosis and emphysema were present. Hale et al (1956) observed in one case large amounts of pure kaolinite dust associated with massive fibrosis without evidence of tuberculosis, and in 28o another large amounts of kaolin dust and excess amorphous silica with a more nodular type of fibrosis and progressive tuberculosis. Experimental work has shown that kaolin does not produce fibrotic lesions in any way comparable with silicosis. It has been suggested that the fibrosis sometimes noted with kaolin results from the admixture of silica to kaolin. This has been shown experimentally by Rutter et al (1952), Policard and Collet (1954) and Schmidt and Luechtrath (1958) who observed that particles of kaolin are always accompanied by Silicat thus we are concerned not with kaolin alone, but with kaolin-silica mixtures. These difficulties explain the differences in the conclusions drawn by various workers in the field of kaolinosis. The role of infection in producing massive fibrosis is also significant (see pulmonary massive fibrosis). The other two fibrous rocks are serecite and sillimanite. Serecite has no commercial importance. There is some evidence that sillimanite may cause interstitial pulmonary fibrosis both in exposed workers and experimental animals (Jotten and Eickhoff, 1944, Gardner and van Marwyck, 1947). Fuller earth pneumoconiosis, cement pneumoconiosis and mica pneumoconiosis which are benign, have also been described. In view of the recent recognition of the problem of pneumoconiosis due to silicates, the pneumoconiosis conference held at Johannesburg (1959)* recommended "as observations on man with regard to the pathogenicity of silicates are incomplete, it is desirable that further observations on man and experiments on animals should be carried out". * Proceedings of the Pneumoconioses conference held at University of Witwatersrand, Johannesburg 9-24 Feb.,1959, Orenstein, A.J. (ed) J.C.A. Churchill (1960). 281 PNEUMOCONIOSES CAUSED BY COAL, INORGANIC AND OTHER DUSTS In recent years the etlopathology of simple coal workers' pneumoconiosis has been extensively described. It has now been shown that coal workers' pneumoconiosis consists of nodules which are small, less firm and fibrotic than silicotic nodules and contain more dust. They are surrounded by a zone of focal emphysema. Numerous small discrete aggregations or drifts of coal dust and sheaths of dust laden cells enmeshed in fine fibrous tissue, principally as cuffs around the respiratory bronchioles are also seen (Heppleston, 1947,1951). The particles size of the dust is 2-3 micron and ends at about 5 micron (Cartwright and Nagelschmidt, 1961). The dilation of ensheathed bronchioles forms focal em- physema which increases with the advance in age of the miners. Both the focal and generalised varieties of emphysema may be found (Gough, 1940, and Heppleston, 1947). Heppleston's (1947) view regarding coal workers' pneumoconiosis has been that it was the mechanical accumulation of dust irrespective of its nature which played a significant part in the pathogenesis of the dust lesions. Policard and Deyuns (1930) observed that pulmonary anthracosis and fibrosis of the lungs of coal workers were merely two phases of the same process. The other view has been that the disease is due to quartz but modified in appearance by the large amount of coal. ference with the Cummins (1927) observed that the inter- lymph drainage of the lung led to the retention and accumulation of coal dust in the pulmonary tissue. Belt and Ferris (1942) noted that the fibrous tissue (reticulin) in these foci was just sufficient to hold together the deposits of particles. 282 There is therefore no accepted view Inspite of extensive research on the subject. Simple coal workers' pneumoconiosis may be complicated by massive pulmonary fibrosis (see pulmonary massive fibrosis). Among the coal miners a condition known as "rheumatoid pneumoconiosis" associated with rheumatoid arthritis has been recognised (Caplan, 1953). The opacities in the lung may develop suddenly or coincide with the onset of arthritis. They often coalesce into large lesions. Gough et al (1955) observed that the fully developed rheumatoid nodule is bigger than the silicotic nodule and is composed of necrotic collagen separated by lines of dust accumulation and surrounded by an inflammatory reaction. recovered. Tubercle bacilli have so far not been Rheumatoid nodules may calcify, or the necrotic material may be expectorated leaving behind a thin-walled cavity. Other forms of carbon (graphite and lignite), metal (aluminium, beryllium, iron, cadmium, tin, nickel) and a large number of inorganic dusts also give rise to a simple type of pneumoconiosis. The inhalation of aluminium dust or the fumes from bauxite smelting produces a pulmonary condition known as aluminosis or "aluminum lung". Goralewski (1939,1940,1941,1943) observed that workers exposed to a high concentration of aluminium dust developed diffuse fibrosis with a tendency to spontaneous pneumothorax. Shaver and Riddell (1947) and Shaver (1948) observed that the disease known as "Shaver's disease" was the result of the inhalation of mixed fumes of very fine particles of silica and alumina. From Britain, investigations did not show any evidence of lung lesions in workers exposed to aluminium or alumina dust (Meiklejohn and Posner, 1957). Again the pathological effects of aluminium dust 283 were reported on the basis of autopsy by Ueda et al (1958) Mitchell (1959), and Mitchell et al (1961). They observed characteristic collections of large amounts of dust and intense generalised fibrosis and Swenson et al (1962) noted emphysematous bullae due to aluminium dust. On the basis of these observations and experimental evidence it has now been shown that under certain conditions, alu- minium and its various compounds can produce pneumoconiosis. The degree of fibrosis varies not only with the chemical structure, but a positive correlation exists between alumina solubility and its fibrogenic activity. The results of experimental research with aluminium and its compounds are so variable as to make it unjustifiable to apply them to man. The mechanism of fibrosis induced by aluminium and some of its compounds therefore requires further in- vestigation. In recent years extensive use of beryllium has become an industrial hazard, for beryllium not only induces systemic toxicity but also causes pulmonary granuloma. Further beryllium produces pulmo- nary cancer in experimental animals, which raises the possibility that human subjects exposed to beryllium compounds may develop pulmonary carcinoma. Further investigations on beryllium are therefore required. The inhalation of iron oxide causes "siderosis". Haematite miners usually develop a sidero-silicosis because haematite ores usually occur along the quartz seams. Electric arc welders also show generalised reticular and nodular shadows in their chest Xrays but no fibrosis (Doig and McLaughin, 1936). Workers finish- ing or polishing silver articles inhale dust of powdered rouge which contains iron oxide of high purity as well as silver particles; 284 they show an aggregate of dust under the pleura and pulmonary vessels, but no fibrosis. Iron oxide when inhaled along with silica dust, for example by foundry workers and boiler scalers, however, does cause fibrosis. There is evidence that iron and steel workers suffer from cancer of all sites more than control groups (McLaughin and Harding, 1956¡ Bonser et al, 1955¡ Faulds 1956). It is now accepted that among haematite miners there was a notable predisposition to the development of tuberculosis which often causes disability and death. RARE EARTH PNEUMOCONIOSES The "rare earth" elements include lanthanum, cerium, praseodymium, neodymium, europium, gadolinium, terbium, dysprosium, holmium, erbium, germanium, thulium, ytterbium and lutecium. Schepers et al (1955) observed radiological changes in the lungs of workmen exposed to oxides and fluorides of certain rare earth elements. Inhalation and intratracheal injection experiments by these workers did not produce fibrosis in guinea pigs, but a year later vascular granulomata with a eosinophilic infiltration were seen. Schepers (1955) with a blend of rare earths with high fluor- ide content noted pneumonitis, subacute bronchitis, and bronchiolitis associated with deposits of the dust. Focal hypertrophic emphysema was also seen but no fibrosis. Mogilevskaya (1961) noted that the effect of mixtures was severer than the individual components. Mogilevskaya and Raikhlin (1963) and Mogilevskaya and Roschina (1964) administered intratracheally the dust of gadolinium oxide and confirmed its toxicity. Ball and Gelder (1966) also showed that inhalation of gadolinium oxide initiated focal areas of interst ' " "ckening around dust-laden macro285 phages, areas of calcification in the region of the alveolar membrane) and elastic laminea of the small pulmonary vessels in micet It was concluded that gadolinium oxide caused only be- nign lesions in the lungs of mice. Hoschek (1966) on the basis of intratracheal injections to guinea pigs of cerium oxide and fluoride observed that these effects of rare earth on pulmonary tissue have however opened up a new field of research, the knowledge of which may be utilised with advantage in the prevention of hazards caused by them, The importance of many non-silicious dusts which cause benign pneomoconiosis is now being realised. Under certain condi- tions they may cause pulmonary impairment. The effect on pulmo- nary tissue of other substances like tin oxide, tungsten carbide, barite, zircon, titanium oxide and calcium fluoride dusts has been investigated, and some of the so-called "inert dusts" have been shown to cause pulmonary damage and disfunction. Combinations of different raw materials are also used in industry today and, therefore, dust exposure from them may consist of a mixture of various substances, e.g. in certain ceramic plants beryllium may be inhaled along with silica dust, and similarly quartz along with asbestos dust. The combined effect of many dusts with other inorganic dusts or other chemicals needs further exploration. NUTRITION AND PNEUMOCONIOSES Study of the effect of a low protein diet similar to that consumed by the mining population in India on the pulmonary silicosis revealed that fibrosis and total collagen content of the silicotic lungs was not significantly altered (Zaidi and 286 Kaw, 1970t Kaw and Zaidii 1970). A synergistic action of low protein diet on silicotic fibrogenesis appeared to be unlikely (Zaidi and Kaw, 1970). The progression of pulmonary silicosis in subclinical ascorbic acid deficiency to guinea pigs took place in almost a similar fashion as in those animals having an adequate ascorbic acid intake (Kaw and Zaidi, 1969). These studies suggest that in miners, silicosis will probably develop uninfluenced by the state of nutrition. INFECTIVE PNEUMOCONIOSES Infective pneumoconiosis has been defined as the modification in a dusty lung of the reaction to a chronic low-grade infection, frequently tuberculosis, in the direction of increased fibrosis (Simson et al, 1931). Infective Silicosis The hazards of the inhalation of silicious dusts have included a high incidence of pulmonary tuberculosis among affected miners. In infective silicosis necrosis and fibrosis proceed side by side, with a preponderance of the latter. The chronicity of the lesions is possible due to the combined action of silica and tubercle bacilli and often these factors were so closely blended that they excercised a modifying influence on each other and the lesions produced were typical of neither. In the presence of a chronic low- grade tuberculosis infection and silica dust in the lungs, the re- action was modified and resulted in large areas of fibrosis. Kettle (1932) however went so far as.to suggest that infective 287 silicosis was an example of chronic tuberculosis which was so modified by the presence of silica dust that a low-grade progressive infection resulted which was accompanied by excessive fibrosis. There are various views regarding the proliferation of tubercle bacilli in the presence of quartz. The necrosis produced by quartz provided a suitable medium for the growth of tubercle bacilli. Kettle (1930) and Price (1931) reported the enhancement of growth of tubercle bacilli by silica In artificial media, but this could not be substantiated by Vorwald et al (1954). Eblna et al, (1960) did not notice multiplication of BCG bacilli in the mononuclear phagocytes ingesting dust particles, but observed that the dust particles destroyed the phagocytes which may be one of the factors to enhancing tuberculosis. Viglianl and Pernis (1959) produced evidence that finely divided silica may enhance significantly the immunological response to bacteria, and therefore infective silicosis was a reciprocal non-specific enhancement of the Immunological response. Goethe (1968) showed an influence on the transport of quartz dust from the lung to lymph nodes, when the animals were given BCG. The proliferation of tubercle bacilli and increased fibrosis in infective silicosis however still requires further investigations. Infective Silicatosis The term infective silicatosis has been used for the pneumoconiosis caused by silicates in which tuberculosis infection is involved. The relationship of tuberculous infection and experimental kaolin pneumoconiosis has been extensively studied. The fact that a mixture of kaolin dust and tubercle bacilli produced an extensive pulmonary fibrotic reaction in experimental animals has assumed 288 great significance in view of the recent clinical report of progressive massive fibrosis in workers exposed to heavy concentrations of kaolin dust (Lynch and Mclver, 1954)• PULMONARY MASSIVE FIBROSIS Pulmonary massive fibrosis was first reported in coal miners from many parts of the world which on X-ray examination produced opacities resembling a golf ball, a sausage or even a cricket ball. The condition assumed greater importance because cases of pulmonary massive fibrosis have also been reported among workers exposed to other dusts like kaolin or haematite (Zaidi, 1969, 1977). The etiology remained uncertain for several decades. Earlier Belt and Ferris (1942) suggested a sporadic factor "X" which caused this type of pulmonary massive fibrosis. The nature of this factor has been a subject of experimental investigations and recent views are summarised below. Silica hypothesis i It has been suggested that'pulmonary massive fibrosis is due to the coalescence of silicotic nodule. Classical silicosis is however rare in coal miners. The other view is that the coal macule is a modified silicotic nodule. Extensive lung dust residue analysis have shown that silica contents in the miners are of the same order if not slightly more as that found in the normal lung. Total dust hypothesis i This theory is based on the assumption that once a certain amount of dust has accumulated in the lungs a process is started which is self-perpetuating. This view appears to be un- likely because the progress of disease is not influenced by further dust exposure. 289 Immunological hypothesis i It has been suggested that pulmonary massive fibrosis may be the result of an antigen and antibody reaction. This is supported by the occurrence of the Caplan syndrome (rheumatic pneumoconiosis) and lung autoantibodies. Burrell (1973) demonstrated that both types of IgA, secretory and serum are involved in the immune response, and such antibodies can be detected in pneumocoriLctic nodules. This theory remains to be further investigated. Infective Faeton The concept that an infective factor was operative gained importance in recent years because of the extensive experimental work done by Zaidi (1977). James (1954) found bacteriolo- gical and histological evidence of tuberculosis in 40% of cases of pulmonary massive fibrosis. Further the discoveries of Mycobacte- rium kansasil and the Scotochromogens in the sputum of miners were other important factors in understanding the mechanism of pulmonary massive fibrosis. Zaidi et al (1955) showed that pulmonary massive fibrosis was brought about by combined action of tubercle bacilli and coal mine dust. Asymmetrical and irregular lesions in guinea pigs were produced by the combined effect of an isonized resistant strain of Myco tuberculosis and coal mine dust, which persisted up to 300 days. The failure to show any tendency to resolution is also seen in coal workers' lung. They suggested that pulmonary massive fibrosis was not brought about by an increase in the virulence of the bacilli, and when fibrous tissue had formed the bacilli died out. It was therefore concluded that coal mine dust plus tuber- culosis infection produced pulmonary massive fibrosis. This aspect was therefore re-investigated by several workers using different 29o strains of Myco tuberculosis, and pulmonary massive fibrosis has been produced (Zaidi, 1969). To what extent a chronic low-grade infection other than tuberculosis along with different types of dust played a part in the pathogenesis of these lesions remained obscure. This was, therefore, investigated by Zaidi et al (1973) with asbestos dust along with a low-virulence organism, namely Candida albicans. This organism is capable of setting up a mild infective stimulus in the lungs and is sometimes found in the normal physiological conditions of miners. Amosite dust was used in our experiments because animals are more susceptible to this variety of asbestos. The animals used were Rhesus monkeys which possibly may have similar an immunological response to that of man and are therefore the best suited primate for experimental asbestosis. From these investigations it was concluded that Candida albicans can act synergistically with amosite dust and produce more extensive pulmonary collagenous fibrosis than caused by either the amosite dust or Candida albicans alone. Experiments were also undertaken to study the lesions, if any caused by máznese dust, in the lungs of guinea pigs and their modification by Candida albicans. The experiments showed that manganese dioxide in the presence of infection produced more fibrosis and definite pneumoconiotlc lesions (Zaidi et al, 1973). The role of organic dust and infection was also studied by Zaidi et al (1971). They investigated the disease of farmers known as farmer's lung caused by the inhalation of mouldy clay. The pa- thological changes were caused by the combined action of hay dust 291 and thermophilic actlnomycetes. Thermopolyspora polyspora regarded as the causative factor was studied in guinea pigs. The lung of guinea pigs exposed to T. polyspora alone showed no discernible connective tissue lesions. The lungs of animals,exposed to hay dust alone produced lesions closely resembling those seen in actual cases of farmer's lung. At the termination of the experiments at 180 days i both interalveolar and intra-alveolar fibrosis was observed with dust alone, but the lungs exposed to hay dust mixed with organisms developed more extensive fibrosis. Zaidi (1977) concluded that extensive pulmonary fibrosis, in the presence of dust whether coal, asbestos, manganese or hay dust, is not only related to tubercle bacilli, but also to other chronic low-grade infestions which are found in the upper respiratory tract of workers. It may be inferred that extensive pulmonary fibrosis is dependent possibly on the synergistic action between the dust and the organism. It was suggested that a regular check-up of any acute or chronic respiratory infection of the workers and its early eradication by prompt treatment may prevent extension of fibrosis. Recent experimental and clinical investigations- have brought to light the role of the infective factor, antinuclear anti-bodies and rheumatoid factors in relation to the damaging action of a number of industrial dusts. The need for further research on the role of these factors in the pathogenesis of dust disease can hardly be overemphasized. 292 »Tricóla ( 1494-1 ">r",j ,ne ^5 Metallica Published (15%) allvisatos.C.P., PontitaI:is,i.n., und Tersis.D (1953),!írit.J.Industr. llod. ,12,43 <tllison,.t.C., Harrington, J.S., Mrbeck,!! and üasb.T (1*57) iníi„led ¡'articles and Vapours 11,121 edited by C.N.Duvles, tendon Perganon Press. vintwoiler.U and Hirscu.G (1956),Arch. 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Examina los sucesivos métodos experimentales, desde Claude Bernard hasta las cámaras de polvo perfeccionadas de nuestros días. Con respecto a la silicosis, presenta trabajos recientes sobre diversas teorías i la teoría de la partícula de sílice recién desprendida, la teoría de la cristalinidad y la teoría del tamaño crítico de las partículas. Esboza la teoría química, sus dificultades y modificaciones en estos últimos años y#la aparición de otras teorías conexas. Analiza la hipótesis inmunológica de la silicosis, las diversas dificultades con que tropieza su aceptación y las ideas más recientes conocidas sobre la acción de los linfocitos T y B en la fibrosis del tejido pulmonar. Las investigaciones clínicas y experimentales sobre la neumoconlosls debida al silicato abarcan la neumoconiosis por el talco de los diversos problemas relacionados con la neumoconiosis por el vidrio y el caolín. El informe señala el problema de las asbestosis y la importancia de la estructura de la fibra. Indica la importancia de las infecciones en la neumoconiosis, la fibrosis pulmonar masiva y los factores nutricionales. 3o1 CONSIDERATIONS ON PATHOLOGY, PATHOGENESIS AND ETIOLOGY OF PNEUMOCONIOSIS Tatsuo SANO and Isamu EBIHARA Division of Work Environment and Occupational Disease, Institute for Science of .Labour, Tokyo, Japan Cooperative efforts In recent years (1948-1978) by clinicians, radiologists and pathologists have evidenced the occurrence of various pneumoconioses in Japan, namely, typical silicosis, atypical silicosis, acutely developing silicosis, asbestosis and some other silicatoses (talcosis, pyrophillite lung, bentonite pneumoconiosis, diatomaceous earth pneumoconiosis, pyrite pneumoconiosis, metal lung (welders lung or iron-oxide lung, metallic aluminium lung, alumina lung, pyrite-cinder pneumoconiosis), carbonaceous dust pneumoconioses!(carbon lung, graphite lung and activated carbon lung), and organic dust pneumoconioses, (Joss-stick lung, cererai dust pneumoconiosis), etc., and their diagnosis was confirmed by autopsy. I. Pathomorphology of pneumoconiosis. The pneumoconiosis tissue changes by dust in the pulmonary area are not only the fibrosis of dust foci, but the airway affections (bronchitis, bronchiolitis, alveolar-wall changes and emphysema) and .blood vessel changes due to the two former changes« Pneumoconiosis can be classified into three types from the viewpoint of j.ts pathomorphological changes. (Table 1 ) . 1. .large nodule pneumoconiosis - only typical silicosisi 2. small nodule pneumoconiosis - atypical silicosis (mixed-dust silicosis), silicatosis, metal lung, carbonaceous dust pneumoconiosis ; 3. pneumoconiosis with bronchiolitis due to dust - asbestosis, Joss-stick lung. 3o5 In the case of large nodule pneumoconiosis, nodules are usually sparsely scattered in the rather intact lung area, though the fibrosis is strong in each lesion. In the case of small nodule pneumoconiosis, on the contrary, the density of nodules is usually high and the intact area of the lung is far less than in the former, though the fibrosis is generally weak, and the bronchobronchiolar changes are stronger than the former. II. Pathogenesis of pneumoconiosis. Prudent histological investigation of about 650 cases of various pneumoconioses and repeated animal experiments led the author to the opinion that pneumoconiosis could be classified from the viewpoint of pathogenesis into two types, namely, the interstitial type and the alveolar type. (Table 2)« 1. Free silica dust or dust containing considerable amount of free silica readily provokes strong collagenous fibrosis in the dust foci, particularly in the pulmonary lymph nodes, and also interstitial changes in the lung field to which the intra-alveolar changes can gradually be added (pneumoconiosis of interstitial type). 2. In the case of asbestosis, other silicatosis, metal lung, 'carbonaceous dust pneumoconiosis, organic dust pneumoconiosis, or almost all other pneumoconioses, however, fibrosis is scarcely or only little noticed in the lymph nodes, and the histological changes in the alveoli resulting in fibrosis are dominant (pneumoconiosis of alveolar type). Progression of pneumoconiotic changes is chiefly caused by 3o4 addition of intra-alveolar changes due to the increase of inhaled dust. The massive fibrosis of pneumoconiosis can be classified from the viewpoint of its formation into two types, i.e. "conflation type by small atherectasis" and "filling up". The former type is found in case of pneumoconiosis due to long term inhalation of considerable amounts of dust, and dust foci are predominantly located in the upper, rear part of the lung (pneumoconiosis of the gradually developing type). In the later type, which is usually provoked by excessive dust inhalation in a short period, dust foci resulting in fibrosis are found not only in the upper part, but also in the lower part of the lung, accompanied with pleural thickening (pneumoconiosis of the acutely developing type). The above-mentioned course of formation is common to all types of pneumoconiosis except asbestosis. Asbestosis is usually characterised by homogenous distribution of dust foci, continued bronchiolitis resulting in bronchioloectasis in the lower part of the lung, due to long-fibered dust. The distribution and nature of dust foci depend not only on the quality as well as quantity of the dust and the duration of dust inhalation and retention, but also on the condition of ventilation. (Table 3). III. Definition and malignancy grade of pneumoconiosis. The common histological changes of pneumoconiosis are not only the fibrosis of dust foci, but also the various affections of airways and blood vessels. Difference of pathological findings between various pneumoconioses is the difference of grade. Therefore, pneumoconiosis should be defined as follows 3o5 "pneumoconiosis Is the lung changes provoked by unsoluble or scarcely soluble particulate matters that form the dust foci, various airway affections and accompanying blood vessel changes"• The conception that the malignancy of pneumoconiosis is related with the potentiality of collagenous fibre production seems to be a partial view paying attention only to one of the factors concerning malignancy. The malignancy must be evaluated by factors which cause malfunction of the lung and pathological changes resulting in earlier death, i.e. air-passage affections. In Japan, permissible dust concentrations have been recommended from this viewpoint (1962). IV. Etiology of pneumoconiosis. According to the autopsy findings and the results of repeated animal experiments, excessive inhalation and sedimentation of dust can provoke harmful pneumoconiosis of alveolar type. (Table 4 ) . From the viewpoint of pathomorphology and pathogenesis, it is not rewarding to discriminate between organic and inorganic dust. Long-term inhalation of dust, organic or inorganic, and its sustained deposition in alveoli can cause pneumoconiosis of various types, if the dust is unsoluble or scarcely soluble. The foreign-body reaction or inflammation is the process in which the action of phagocytes and proliferation of cells including the fibroblast and fibrocyte in the presence of excessive foreign matters (dusts) occur, resulting in cell degeneration and fibrosis of various grade. In this sense, the fundamental and common cause of pneumoco- 3o6 niosis is the foreign body inflammation due to excessive dusts. Consequently, every kind of dust is active and every pneumoconiosis is harmful. 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O I H V • u A' •» i £ a 9 SET o Ort -a SA O M o ri a « M V fil S3 ' I î* M g* H h II 58. S3 SS 18 £3 M s« Vi n l K« O u % »I Sá I I I • P I ' • a 1 & ï i X «rîîii MïïS» *2 §§ fi se •H 3 « O ce o * T> n t et n •a Hi« u O 25 «4 fi «îrH »s • fi a d « 3 •« I JiSss. ¡lift | l i h u you-3 Il» JBT° 9A TY *8 3o9 •,» - » • 2C33S3 Table. J Btlmtkmikìp Between Pathological Findings and tat Quantity and Period 0/ Inhal td Du ¡I "——^^iàoTi of Pn. ( SINO) Usual Pneumoconiosis Acutely Developing Pn. Quantity of Dust large amount extraordinary large amount Period of Dust Inhalation relatively long (10 years or more) relatively short (1-Syearsor within lOyears) Distribution of Dust Foci massive fibrosis chiefly in superior .posterior parts M.F. in inferior parts partial thickening in endsuge almost universal thickening in early stage Intraalveolar Chance addition to the interstitial change early outbreak in wide lung area Emphysema remarkable in endsuge Changes """" -— neural Change Table. 4 type I II III death by cor pulmonale or complication of pneumonia or tbc. before the dvelopment of remarkable emphysema three types of Dust Reaction in Experiaental Pneumoconiosis Fibrosis in Lung (•••) (••)-(•••) <•) Substance type of Pn. Free S i l i c a (quarg e t c . ) lyaphatic Fib.in Lymphnode <•••) (•)-(••) (-) (SANO) Metalle Alunlnua Aluala Pyrophyllite e t c . Asbest, Graphite Carbon Black. Organic dusts 31 o alveolar alveolar Patología y patogénesis de la neumoconlosis. T. Sano e I. Eblhara (Japón) De acuerdo con la atenta investigación histológica de 360 casos de diversas neumoconlosis y con repetidos experimentos en los animales, la neumoconiosis puede clasificarse en varios tipos desde el punto de vista de su patogénesis o de las modificaciones patomorfológicas. I. Desde el punto de vista de la patogénesist 1) neumoconiosis de tipo linfático. Se produce una fuerte fibrosis colágena y los cambios intraalveolares se suman gradualmente a los cambios intersticiales en la zona pulmonar (sílice libre)t 2) neumoconiosis de tipo alveolar. Se producen en los alvéolos importantes cambios histológicos que acarrean fibrosis, la cual, sin embargo, se encuentra rara vez en los linfonódulos (asbestosis, aluminosis, talcosis, neumoconiosis de tierra con diatomeas, neumoconiosis de la pirofilita, pulmón de soldador, neumoconiosis de la pirita, pulmón de minero del carbón, etc.). II. Desde el punto de vista de los cambios patoraorfológicosi 1) neumoconiosis con grandes nodulos. Los nodulos están bastantes desparramados en el tejido pulmonar relativamente intacto, pese a que la fibrosis es importante en la lesión (silicosis clásica)» 2) neumoconiosis con nodulos pequeños. La densidad de los nodulos suele ser elevada y la parte intacta del pulmón es mucho menos que en la primera forma, pese a que la fibrosis es generalmente débil (silicosis con polvos mixtos y casi todas las otras formas de neumoconiosis)i 3) en la asbestosis y la neumoconiosis causada por polvos orgánicos predominan la bronquiolectasia y el enfisema por inflamación repetida en la zona inferior del pulmón. 311 lv/3 NOCIVITE VARIABLE DES POUSSIERES DE SILICE SELON LEUR ORIGINE. INFLUENCE DE CERTAINS MINERAUX D'ACCOMPAGNEMENT L. LE BOUFFANT, H. DANIEL, J.C. MARTIN Centre d'Etudes et Recherches des Charbonnages de France, Verneil-en-Halatte, France. Introduction En matière de toxicologie des poussières, une importance particulière a toujours été accordée à la silice libre, ou plus exactement au quartz présent dans les poussières d'une grande variété de type6 d'exploitations minières. Aussi, la détermination du risque présenté par l'inhalation de ces poussières comporte-t-elle le plus souvent, soue une forme ou sous une autre, l'appréciation de la quantité de silice libre contenue dans les particules ihhalables. Cependant, jusqu'à présent,cette appréciation ne prend pas en considérations l'éventualité d'une différence de nocivité entre les silices de différentes origines. Des observations déjà anciennes ont cependant fait apparaître qu'il pouvait exister des différences importantes de risque de silicose entre certaines mines et ceci pour des teneurs en quarts équivalente. De notre cOté, nous avons constaté des écarts en matière d'endémie pneumoconiotique entre les bassins houillère français pour des teneurs en quartz comparables sans que ces écarts semblent pouvoir être attribués à des différences marquées dans les concentrations en poussières ou les granulométries des particules (1). Ces constatations couduisent à mettre en cause des variations possibles de la nocivité du quartz lui-même en fonction de son origine ou de 6es transformations. Afin de tenter d'élucider ce problème, nous avons entrepris d'étudier la nocivité des poussières de quartz provenent de divers horizons géologiques (quartz contenu dans les poussières de mine de charbon) sous l'angle de leurs propriétés fibrös \-vis des tissus. NOCIVITES COMPAREES DE POUSSIERES DE QUARTZ BRUT Trois variétés de poussières de quartz <J>/*m, à savoir du quarts de Madagascar,, du quartz synthétique et du sable de Nemours ont été inoculés par injection intra-peritoneale à des rats à la dose de 75 »g. Au bout de trois semaines, les animaux ont été sacrifiés et les lésions ont été examinées. Les résultats, portés dans le tableau 1, montrent que le pouvoir fibrosant de ces trois sortes de silice se classe en deux groupes distincts : d'une part le quartz de Madagascar et le quartz synthétique doués d'un pouvoir fibrosant élevé, d'autre part le sable de Nemours faiblement nocif. Il apparaît en outre que la nocivité du quartz synthétique est aussi élevée que celle du quartz de Madagascar, malgré une teneur en quarts, mesurée par diffraction de rayons X, nettement inférieurs. A partir de cette observation, deux hypothèses peuvent être formulées sur les causes des différences de nocivité existant entre ces variétés de quartz: 1ère hypothèse: 2ème hypothèse: leur nocivité propre est différente il existe des modifications au niveau de la surface des particules de quartz. (Voir tableau 1.) VH a o «Otr\ «M O O -ri*-» d i o U) «D B ho hOv-* O vo « (\l a .* ni VO r^ ir\ O H B H b O (S U Oi d o do o •s °* :»> IM at h **• 03 a Q> > +> d (S to o o d fi A3 *"x •tí ta M d ^ 09 O •tí-H •H 10 i\l oc H 09 ITS oc •tí <\1 43 O d (0 d O •H % U •S •P <H o «o 09 o<a> OiH o «u H (H fi 3O •*"•>* H d ^ a> 8 H ^^ -* \o 5 IH M •P O U d os tiS.. •H h 9 OTJ 315 to O 10 (0 «0 IS T) 09 S o 3 c •H 4-> o XB 4> d >> w r-< O o •tí .O 03 W o ä ä 55 ID d •H O 3 +>«—' O U d a O 31 EH O e Vi oc mours I a U IS ti H a o r-t c^O •ri M o •H m •o H X Pi a 09 O •tí ai H03 •p o +> o o ids io a o a> •tí a H E~ o *H sag H O to N +> • (4 en es o 31 d O -H (0 o •o o Pi •H D «M ro N k. Q: 3 ^ C» ÏS y> !*J f* ^ 1 •^ $ •1 S S %»5 ÎS ki Ui Q: ? ÍO o SJ K ^ -^ <o c* 5t 316 1 « c •v» $ V s »5 i RECHERCHE D'UNE DIFFERENCE DE NOCIVITE INTRINSEQUE DES QUARTZ Dans un premier essai, la comparaison entre le quartz de Madagascar et le sable de Nemours à été poursuivie afin d'étudier l'évolution de leur nocivité dans le temps. Pour cela, ces deux variétés de poussières ont été injectées à des rats par voie intratracheale. Les animaux ont été sacrifiés après des délais d'évolution croissants et l'importance des lésions a été appréciée en déterminant l'augmentation de poids des poumons et la quantité de collagène formé et en procédant à des examens histologiques. Les courbes'obtenues dans la(fiq.)montrant que le quartz ds Madagascar possède un pouvoir fibrosant très important dès les premiers mois. Au contraire, le sable de Nemours est presque sans effet pendant ce laps de temps, mais sa nocivité augmente progressivement lorsqu'on prolonge le délai d'évolution et finalement la vitesse de formation de collagène rejoint celle du quartz de Madagascar (2). Dans un deuxième essai, des poussières de différentes mines de charbon ont été incinérées et le quartz qu'elles contenaient a été extrait par attaque phosphorique. Les particules ainsi obtenues ont été injectées a des rats et les lésions obtenues après trois mois ont été comparées à celles produites par du sable de Nemours et du quartz de Madagascar ayant subi le même traitement chimique. Les résultats du tableau 2 montrent que les quarts ainsi testés possèdent, quelle que soit leur origine, un pouvoir fibrosant elevé et comparable. 317 Tableau 2 - Nocivité comparée de quarts extraits de poussières de mine, de sable de Nemours et de quartz de Madagascar (Test I.T. 3 mois) Origine du quartz Poids des poumons (g) Poussières( Ostricourt de ( la Houvre mine ( Gardanne Sable de Nemours Quartz de Madagascar Collagène formé (mg) 2,55 2,63 2,92 12,8 13,5 16,6 3,25 13,4 3,05 18,1 De ce fait, ils tendent à infirmer l'hypothèse d'une différence de nocivité intrinsèque des quartz en fonction de leur origine et accréditent au contraire l'hypothèse d'une inhibition plus ou moins marquée mais passagère de la nocivité de certains quartz. MECANISME DE L'INHIBITION DE LA NOCIVITE DD QUARTZ L'action toxique des poussières e'exerçant nécessairement par leur surface externe qui se trouve au contact des cellules et des tissus, il convenait de rechercher la cause de la modification de nocivité du quartz dans une transformation superficielle des grains de quartz, notamment sous l'action de certains minéraux. 318 Pour cela, noue avons cherché a réduire artificiellement le pouvoir fibrosant du quartz de Madagascar en le mélangeant avec des poussières de mine de bharbon et, dans un deuxième essai, avec les matières minérales extraites de ces poussières. Les mélanges ainsi obtenus ont été testés par injection intratracheale sur des rats, et leur action comparée à celle du quartz de Madagascar mélangé à des quantités égales de poussière inerte (oxyde de titane) afin qu'.il se présente dans le infime état de dilution. Tableau 3 - Modification de la nocivité du quartz par des matières minérales (Test I. T. 3 mois) Poids des poumons (g) Collagène formé (mg) Quartz + inerte (TiO,) ¿ (7,5mg) (50mg) 3,33 28,6 Quartzt poussières de mine (7,5mg) (50mg) 2,54 8,6 Quartz+ matières minérales (7,5mg) (provenant de 50 mg de charbon) 2,05 10,0 Nature des poussières Les résultats obtenus (tableau 3) montrent que les poussières de charbon utilisées exercent sur le quartz un effet inhibiteur important. 319 De plus, cet effet se montre localisé dans les matières minérales dont le pouvoir anti-quartz est comparable à celui des poussières totales. Il n'est pas provoqué par un simple effet de dilution, car le quartz mélangé à une inerte demeure fortement nocif. Afin de rechercher si l'inhibition est produite par une réaction moléculaire entre le quartz et certains constituants solubles des matières minérales, une suspension aqueuse de ces dernières a été dialysée contre une suspension de quartz et le quartz ainsi traité a été testé sur l'animal selon la même méthode, et ses effets comparés à celui d'un quartz traité à l'eau pendant le même temps. Tableau k - Influence des produits de dissolution des matières minérales de poussières de mine sur la nocivité du quartz (Test I. T. 30 mg - 3 mois) Nature des poussières Poids des poumons (s) Quartz témoin Collagène formé (mg) 91,5 Quartz traité par dialyse 1,69 5,6 Les résultats du tableau k montrent qu'il existe bien un transport de produits de dissolution des matières minérales vers les particules de quartz se traduisant par une inhibition de la nocivité du quartz, tout au moins pendant les trois premiers mois de séjour des poussières dans le poumon (durée du test). Il apparaît donc clairement qu'il s'est produit une modification de l'état superficiel du quartz. 32o NATURE DES MINERAUX PROTECTEUR. L'identification des minéraux capables d'exercer cette action inhibitrice a pu être faite dane un certain nombre de cas. Pour cela, nous avons entrepris l'étude systématique de l'action anti-quartz des minéraux argileux rencontré dans les poussières de mine. Bien que cette étude soit loin d'être achevée, il apparaît d* ores et déjà qu'il existe entre les argiles des différences importantes d'efficacité. Tableau (S)Effets protecteurs comparés de l'illite et du koalin (Test I.P. 3 semaines) Nature du mélange Poids des lésions (g) Collagene formé par mg de quartz (mg) Quarts + illite 0,80 1,7 Quartz + kaolin 1,87 3,8 Témoin (quartz 1,30 3,3 TiOp) C'est ainsi que de l'illite dans la proportion de 50 % inhibe très fortement l'action fibrosante du quartz tandis que le kaolin n'exerce aucun effet protecteur apparent mais ajoute au contraire sa faible nocivité propre â celle du quartz (tableau 5 ) • Divers autres minéraux argileux possèdent à des degrés divers un pouvoir inhibiteur de la fibrose silicotique. Parmi eux, il convient de citer la inontmorillonite, dont l'analyse par diffraction de rayons X a révêlé la présence dans le 6able de Nemours (2). 321 La formation d'une couche protectrice à la surface du quartz peut être mise en évidence par des mesures do solubilité et par diffraction électronique sous incidence rasante (3). De plus, une réaction colorée à l'aurine montre que les minéraux argileux libèrent en milieu aqueux de l'aluminium dans des proportions d'autant plus grandes que le minéral exerce une protection plus forte. Il apparaît donc que l'effet protecteur des argiles est dû à la formation d'une combinaison de l'aluminium à la surface du quartz. Cependant comme nous l'avons vu précédemment dans la figure,la courbe de variation de la nocivité du sable de Nemours en fonction du temps montre que cette combinaison ne possède qu'une stabilité relative dans le temps et que la couche superficielle du quartz est progressivement remise à nu dans les milieux biologiques. QUARTS ET SILICE AMORPHE L'ensemble de ces résultats conduit par ailleurs à minimiser le rôle de l'état cristallin dans les variations que l'on constate dans le pouvoir fibrosant de la silice libre et à rattacher davantage cette propriété à l'entité silice elle-même et ses variations à un "masquage" plus ou moins accentué des groupements SiCs de la surface des grains par des combinaisons dues à l'action de minéraux exogènes. A l'appui; de cette thèse, nous avons montré (tableau 6) que l'état cristallin n'est nullement indispensable pour que la silice manifeste des propriétés fibrosantes et que la silice citreuse possède pratiquement la même toxicité que le quartz de Madagascar ou le quartz synthétique, ces deux derniers possédant eux-mêmes un pouvoir fibrosant identique malgré des teneurs en quartz, déterminées par diffraction de rayons X, nettement différentes. Des observations analogues ont été faites avec diverses silices amorphes obtenues par voie ignée ou aqueuse (if,5). 322 Tableau 6 - Effet fibrosant de différentes forme de silice ! Nature de la silice Teneur Si0 2 (56) Quartz de Madagascar env. 100 Quartz synthétique env. 100 Silice vitreuse env. 100 Teneur en quarts (56) 100 Colagène formé par mg SiO, (56) 2,60 2,64 0 2,30 CONCLUSION Cette étude fait apparaître essentiellement que la nocivité propre du quartz ne varie pas de façon importante en fonction de son origine, mais que les différentes constatées paraissent se rattacher plutôt à des effets d'inhibition plus ou moins marqués sous l'action de certains minéraux capables de libérer de l'aluminium en milieu aqueux. Ce phénomène peut avoir eu lieu au cours des âges géologiques ou se produire seulement dans le milieu biologiques du poumon. Quoi qu'il en soit, cet effet inhibiteur, dû à la formation d'un film protecteur à la surface des grains de quartz, disparaît avec le temps lorsque ce film est solubilisé ou que l'aluminium libérale de l'argile est épuisé. 323 BIBLIOGRAPHIE (1) LE BOUFFANT, L.; MARTIN, J.C.; DANIEL,H. in: Lutte technique contre les poussières de mine - Luxembourg 11-13 octobre 1972, 137-150. (2) LE BOUFFANT, L; DANIEL, H.J MARTIN, J.C.; BRUYERE, S. (1977) C.R.Acad. Se. Paris, Série D - 2£5_, 599-602 (3) LE BOUFFANT, L.; DANIEL- MOUSSARD, H.; MARTIN, J.C. CHARBONNIER, J.; LETROT, M.; POLICARD A. (1969) Arch. Mal. Prof. ¿0, 305-310. (k) CHARBONNIER, J. (1958) Die Staublungenerkrankungen, Ban 3, 215-220. (5) STRECKER, F.J. (1955) Grundfragen Silikoseforach. I, 61-73. 524 L. Le Bouffant, H. Daniel y J. C. Martin (Francia) Al estimar cl riesgo de silicosis que encierra la inhalación de polvos de cuarzo sólo se tiene en cuenta la intensidad de la exposición a los polvos, sin tomar en consideración las posibles diferencias de nocividad de la sílice inhalada. Sin embargo, según diversas constataciones. los efectos fibrosantes de las partículas de cuarzo difieren claramente de acuerdo con su origen. Así, con igual contenido de sílice, ciertos polvos de cuarzo procedentes de filones son en extremo fibrosantes, mientras que otros, de naturaleza detrítica, parecen poco nocivos en los ensayos biológicos. De igual modo, en las minas de carbón, los datos epidemiológicos muestran que, con idéntico contenido de cuarzo, el riesgo de neumoconiosis puede variar considerablemente de un yacimiento a otro. Se han examinado dos hipótesis i por un lado, la existencia de diferencias en el grado de nocividad propio de los cuarzos según su origen, y, por otro, la influencia de algunos otros minerales presentes que pueden modificar la nocividad del cuarzo. Utilizando como referencia el elevadísimo poder fibrosante del cuarzo de Madagascar, por medio de ensayos de larga duración realizados con animales, se demuestra que la nocividad de determinados cuarzos detríticos (arena de Nemours), inicialmente débil, aumenta progresivamente según el tiempo transcurrido, hasta alcanzar por último la nocividad del 325 cuarzo de referencia. Asimismo, los cuarzos extraídos de los polvos de las minas de carbón encierran en estado puro un poder fibrosante comparable al del cuarzo de referencia, cualquiera que sea el polvo de origen. Las diferencias de nocividad que puedan existir se deben en realidad a la acción protectora de ciertos minerales arcillosos que acompañan al cuarzo en la arena o en los polvos de mina, acción producida por una reacción superficial entre la arcilla y el grano de cuarzo. En los medios biológicos, el fenómeno no es permanente, y la nocividad propia del cuarzo reaparece progresivamente si no se renueva la sustancia protectora. De estas observaciones se extraen consecuencias prácticas sobre la apreciación del riesgo y sobre una terapéutica preventiva. 326 17/4 CHUCE DE SURFACE ET CYTOTOXICITE DE LA SILICE QUINOT E., CAVELIER C , PIERCERON n.G. Contre d'Etudes et de Recherches des Charbonnaoa» de France VERNEUIL - EN- HALATTE- FRANCE Des études du CER CHAR ont montra que l'aluminium était exoérimantalement un inhibiteur de la nocivité pulmonaire du quartz. L'intérêt porté à de tels phénomRnes dfi protection, mame transitoires, noua a conduits a envisager un mode de fixation possible dR l'aluminium sur la charpente du cristal et a rechercher si d*autre9 atomes pouvaient jouer le même role. Il serait alors légitime de poser comme hypo- thèse de travail que certains da cea atomes puissent être empruntés aux composants organiques du cytoplasme et de la membrane cellulaire, phénomène en rapport avec la cytotoxicitô du quartz. GENERALITE 1 - Structure de3 complexes alumino-slllciques L'aluminium est associé au silicium dans les composés minéraloqiques naturels de deux façons différentes : - soit comme cation isolé dans les silicates d'alumine. Dans ce cas, Al assure la liaison des tétraèdres Bt peut être remplacé par d'autres ccations. l'aluminium est alors hexacoordonné. 327 [sioj En général," VV '-> // X /•-' \ ^ • \ STRUCTURE D'UN TECTOSILICATE : LE QUARTZ B.T. (d'après BERRY et MASON,1959) 528 soit en particinant a l'édification das anions tetraédriquas AIO. au lieu et place du silicium. Les orou- r pâmants SiO, alumino-sllicates. i5- etIAlO forment la charpente des Dans ce ca3, l'aluminium est têtracoordonné. A ce nrnupe anpartiennent les feldspaths et les zôolithes. Dana quelques cas, l'aluminium joue un double role et le minéral est a la fois un silicate d'alumine et un aluminosilicate. Il est donc possible que l'aluminium, inhibiteur de la cytotoxicité du quartz, s'insère dans la charpente du cristal en se substituant, au silicium libéré, a la faveur du désordre superficiel qu'entraîne la dissolution de SiO_. S'il en est ainsi, des charges nôoatives apparaissent la ou les atomes d'oxyqene sont liés d'une part a un atome de silicium, d'autre part a un atome d'aluminium. Il en résulte la formation d'un site acide au sens de BRONSTED (source de protons). 2- Acidité des catalyseurs alumino-slliclquea L'acidité des catalyseurs industriels siliceux et aluminosiliciques se rattache e deux types : - d'une part celui des silanols qui forment l'ensemble de la population des site9 acides de la silice hydratée. A température ordinaire,.l'eau 9e condense sur les aitaa conformément au schéma suivant: -OH + H?Q : ; > ' 329 0 >Si n + H.,0 L'ion hydroxonium (H,0)*rend compte du caractère acide de ces cele avant calcination. Après chauffage a 600° C (20 h) ces fonctions acides se raréfient; après chauffage â 900 °C (5 h) elles ne sont plus détectables. - d'autre part, celui dos sites qui confèrent aux catalyseurs de carcking du type zêolithe 1 acidité de BBÓNSTED. Ils proviennent essentiellement du déficit de charge de l'aluminium tetracoordonné dans le réseau mixte Sil)^ *- r ~i 5JAXOJ A partir de 3O0P C, les sites de BROHSTED se transforment en sites de LEWIS (accepteurs d'un doublet), tout en restant liés a la structure mixte des tétraèdres ayant pour centre soit un atome de silicium soit un atome d'aluminium. Les deux fonctions acides coexistent aux environs de 500 »C. Après chauffage à 900 *C (5 h ) , elles ne sont plus détectables. Ce type de site acide peut être mis en évidence au moyen des indicateurs colorés de HAMMET, par exemple le p-dimpethyl-amino-azobenzène dans le benzène (mêthyl jaune). La réaction est utilisée en pétrochimie pour déterminerla qualité de certains catalyseurs de craquage, connus sous le nom de tamis moléculaires. MATERIEL ET METHODES FIXATION DE L'ALUMINIUM STO TA SILICE 1.- Nous avons recherché le comportement de différentes silices ayant au non fixé des atomes d'aluminium, après calcination a 105° C 600° C et 900° vis-à-vis de l'indicateur nôthyl jaune, c'est-à-dire recherche l'existence et la stabilité des sites acides. 500 mg de quartz fraîchement broyé â sec jusqu'à une dimension voisine du microjiitre sont mis on suspension dans l'eau distillée avec de l'alumine colloidale hydratée. Après dour.e heures d'agitation la suspension est lavée, puis séchée 20 heuren a 105° C. On applique ensuite lo te.ot au methyl jaune dans le benzène. Le quartz prend alors la couleur 33o {ouge caractéristique ds cet indicateur pour des pK inférieurs e 3,3. Ou quartz agiti seul dans l'eau distillée ne fait pas virer le réactif; il en est de même pour l'alumine hydratée desséchée à 105» C. Le quartz broyé, agité dans une suspension d'alumine hydratée dans un tampon SORENSEN, ne donne une réaction positive, après séchage s 105B C que s'il a été soigneusement lavé à l'eau distillés pour éliminer les cations qui empoisonnent le catalyseur alumino-silicique formé dans la couche de haute solubilità. Si on nje pas opéré ce levage les sites acides apparaissent cependant a 6000 c. Le quartz décapé de la couche de haute solubilité par action a chaud d'une solution ION de soude et dialyse fixe l'alumine en floculent. Desséché e 105D, il ne présente pas de sites acides décelables au méthyl jaune, mais ceux-ci apparaissent après dessication a 6008 puis 9000. En diminuant progressivement le quantité d'alumine mise en présence du quartz, on peut observer le virage au roune de l'indicateur Jusqu'à 1 à 2 mg d'alumine pour 500 mg de quartz. La fixation de l'aluminium est largement indépendante de l'accidité du milieu-aqueux dans lequel sont agitas quartz broyé et alumine hydratée. L'alumine se fixe pour des pH compris entre 5 et 9. Lorsque Si0_ et fll-0 sont en présence, la solubilité de l'alumine est voisine de zéro pour des pH compris entre 4,5 et 11, tandis que celle de la silice est réduite elle-même à . 15 ppm au voisinage de la neutralité. Un phénomène semblable se produit a la surface du quartz dans la couche de haute solubilité. Plais l'alumino-silicate qui se forme a la surface du quartz se distingue en partie par ea résistance au cours d'un traitement thermique. 2.- Nous avons expérimenté sur un tamis moléculaire contenant B7% de Si0.,13 % de A1.0-, obtenu par coprécipitation d'orthosilicete de soude et de sulfate d'aluminium. Le précipité s été neutralisé par HCl puie traité a l'ammoniaque pour remplacer per N H J les ions N a * neutralisant les sites acides. Apres dialyse et calcination, on obtient par départ d'amoniac, un tamis protonique (acidité de BR0NSTED) ouis par deshydratation un' tamis acide uu sena de LCUIS. 331 Apres chauffage a 99fie C (5h) la réaction au méthyl jaune est négative. (Tableaux 1 et 2). Un dosane en retour par la butylamins permet de fixer ¿.'ordre de grandeur du nombre des sitas acides disoonibles a la surface des différentes formes de silice ou des tamis moléculaires étudiés. (Tableaux 3 et 4 ) . RESULTATS L'aluminium se fixB donc sur la quartz ou plus exactement dans la couche a haute solubilité, en s'insôrant dans le système tridimensionnel tétraédrique, a caractère cryptocristallin dans sa partie profonde, hydraté et soluble dans sa partie superficielle. Les différences de comportement a haute température entre le quartz agité avec de l'alumine et les composés silice-alumine laissent a penser qu'il se forme un voile zéolithique en surface mais qu'en profondeur l'aluminium est lié au réseau de tectosilicate du quartz; sinon, on verrait disparaître au-delà de 600 0 C les sites acides comme on le constate pour los tamis moléculaires. Il semble bien que la structure du quartz ou même celle de la couche crypto-cristalline confere uno solidité particuliere a la combinaison Si0_/ AI0O3 8 t traduit une affinité spécifique de l'aluminium pour le rés,eau tétraédrique de la silice, la ou les défauts lui permettent de l'aborder. Tette affinité serait alors indépendante du système cristalina Elle ne siqrtB pas non plus un simple phénomène d'épitaxie. Nous sommes conduits a nous demander s'il existe d'autres atomes capables de donner, comme l'aluminium, des inns tétraédrinuns et si certains d'ontre eux ont In même dimension nue 1- -1, r Tiles anions isométri.oues [„.}- " H ' 332 JI in z f l UJ z c m o * *u.« Ul IVI Z UJ M CC 1 O u. u. N-^ z »-4 u <c l a _j o o >- en X K E UJ E 1 0009 » O-< * cj a D a „ *-i in o z o »—1 UJ ri z e t-t K L> cr Ul cr UJ K QO Li- U ai UJ Q- a K u. v- e IO UJ n UJ a Kl JZ CJ et o CM U a 1 in o n 3 O er o K cr tr o _i • *— UJ* 3 ce r» CJ O Ul >-i n Ul or. K a z K cr cr o _i o 3 cr UJ _i UJ tn z t-< UJ tv! CJ UJ m z cr t_> n o CJ / / K / •- / / / o *" oH / / uj in or tn 3 UJ K O CC / or / / 3 / / / UJ CJ fi -> Kl tn / / / / / / / / / / / UJ Q. 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Oí CD #H O O CSI fH CT> f-l O o co f-l f-H f-l f-l O (J X cu CN in o fH X X IO X n UH / / / *-H 1U l CC DCJ t-> UJl-i / / / / ce in 3cn / / t-UI / aro / t QLJ / / / / / / E: UJ UJ cj *-<1 •- / / •H / <" / ^ / Q / / / / / UJ £• o: UJ tr CC _J Z> O gSj«o «° « E E - £> - <o £ «^ uCI - 336 _i UJ CJ D ce UJ ce ll'ARTZ BROYE (5 ECHANTILLONS) z o SILICE H Y D R A T E E PRECIPITEE .-i - Tons susceptibles de s" suhritltuer au Silicium La variété ries alumino-silicates montre que l'aluminium se substitue facilement au silicium. Cela tient, outre son abondance dans la lithosphère (8, 13 %); - d'une nart a la orando différence d'électro-nérativitô rie l'aluminium et dp l'oxygène au sens de PAULING (1,74 et 3,50 respectivement), donc a l'énergie importante de la liaison ionique Al-0, - d'autre part,, au moyen dB ..S*-qui permet la tétracoordinence de cet élément avec l'oxvqene, les anions r r -|4- Si04 et is. A10J étant isométriques. Ces deux caracteres de l'aluminium appartiennent a' d'autres corps que l'on peut identifier a partir des regles de substitution développées par GOLDSCHPIIOT sous le nom dB renies de diadochie, en précisant la natura (covalsnce ou électrovalence) et l'intensité de leur liaison avec l'oxygène. Pour cela, il est commode da porter sur un diagramme selon GOLDSCHPIIOT la dimensión at la charge ionique des éléments le plus coramment rencontrés (Fig.l). A la lecture du diagramme dé GOLDSCHPIIDT on voit donc que le nombre d'éléments capables d'une tétracoordinence avec l'oxyoène ont restreint : Be 2 t , A l 3 * , G e 4 + , \JS*, As 5 , p5t Cr6*, Se , et peut-être quelques-uns de ceux qui sont a la limite de la bande: re3*, B 3 | Ca3'*' , Pln 4+ , Te 6 "*", S6*. De plus, un élément pourra se substituer au silicium, si .1 n rf.imrnsinn dp l'en.lon tétraértrique formé est isométrique de 337 338 ri 3 - r >- r >-• r > niO^ : r.p. nui est le can do , IrranJ VO^. I > nsCI /J Mais pour qu'un atome soit caoablo d'une telle substitution encore faut-il que l'énernie da liaison soit du même ordre de nrandeur que celle do la liaison Si-R. Cela nous oon- duit a rechercher lee éléments qui sont des formateurs de réseau (Network formera) capables par associations d'anions tétraédriquea de donner'des éléments tridimensionnel;-, comme dans les tectoailicates ou bidimensionnels comme dans lea phylosilicatas. Voir:(tableau 5 ) . La comparaison de l'ensemble de cea données conduit a penser que les ions Al , Ge , J3 y— et As' peuvent se substituer a Si dans le tétraèdre!-.- I " ou s'insérer dans le réseau du quartz a la faveur de sa désorganisation superficielle. INTERPRETATION ET COrWENTAIRES " Cytotoxicity de la silice et son Inhibition Les théories qui tentent d'expliquer la cytotoxicité de la silice se rattachent globalement a trois types. Oans le premier, les produits de disolution dispersés dans le solvant sont responsables de la nocivité; dans le second, l'influence du réseau cristallin sur le pouvoir fibroqene est fondamentale et le troisième type est mixte. La théorie de la solubilité a été abandonnée sous sa forme orioinBlle. 339 TABLEAU 6 :TARLEAU DES Eí'ERHIES DE LIAISON AVEC L'OXYGENE (EN kcal PAR LIAISON-GRAWIE D'APRES UN TRAWAIL DE SUN CITE PAR PEYCHES. MODIFICATEURS DE RESEAU FORMATEURS DE RESEAU 104 Li 36 101 Na 20 P 111 K 13 \l 112 Rb 12 Ge lOfl Cs ID "7 fin 37 119 Ca 32 Sr 32 Rn 37 Si Al (coord 4) fia (coorti 3) n < (cnord A) 09 34o P.i.ßn que la nocivité de la silice varie avec 1 P système de cristallisation, c l u t - c i ne peut seul rendre compte des faits connus. On pourrait résumer l'état actuel de la question en reorenant les conclusions de CHARBONNIER et COLLET qui admettent, hypothétiquement il est «rai, que "la toxicité de la silice sa situe a sa surface, sous la forme probable d'une couche de silice hydratée qui est le toxique cytoplasmique". La couche responsable apparaît, a la limite de la dissolution, comme désoroanisée tout en conservant une partie profonde de cette couche, ou l'action du "Uartering" est encore peu sensible, qui est opérante dan3 la toxicité du quartz décapé. La localisation presque certaine de la cytotoxicité ne présage en rien les mécanismes de son action, et plusieurs théories ont été développées sur le sujet; une des premieres voyait dans l'épitaxie sur la structure résiduelle du réseau, l'oriqine d'un phénomène inductif. Une théorie que l'on peut appeler catalytique a été développée ensuite, en particulier par STOBER. Pour cet au- teur les silanols seraient responsables de l'état d'activation de certaine» molécules organiques. Outre que les silanols sont présents a la surface de nombreux silicates naturels et des tamis moléculaires silice-alumine, leur action catalytique n'apparaît qu'a haute température et en milieux non aqueux. De plus, le seul polymorphs da la silice ou le nombre de coordinence du silicium et de l'oxygène soit huit, la stishovite, ne présente pas de cytotoxicité bien que sa solubilité soit peu supérieure a celle du cristobalite. 5*1 Il est remarquable de constater que l'aluminium qui se substitue facilement au silicium dans 1'assemblarle A tétraédrique des tectosilicates, est en même temps un excellent inhibiteur de la cytotoxicité du quartz. Le pouvoir protecteur pourrait être associe a la proprietà que possede l'aluminium de se substituer au sili? cium dans le réseau tétraédrique ou l'environnement géométrique des atomes reste partiellement on place au cours de la formation de la couchs hétôrooene de silice hydratée. En effet, la ou se produit l'action cvtntoxique, on rencontre a la fois un réseau encore ordonné de tétraèdres et des motifs détruits par dispersion de SiO_. L'aluminium capable de tétra-coordination prend la place des atomes de silicium disparus et donne des sites acides, fiais le germanium, le vanadium l'arsenic, le phophore, le soufre, pourraient peut-Btre jouer le mema role. Si l'aluminium an,it comme inhibiteur de la cytotoxicité du quartz en comblant un vide potentiel dans les tétraèdres en voie de dislocation, nn peut penser que cet élément interdit par cola même une réaction du même type responsable de la toxicité mettant en jeu un atome d'un des composés organiques du cytoplasme ot riRR mnmhranes cellulaires. r, cet titre, le nhosnhore pourrait jouer un role particulier. Mous avons vu en effet que cet élément peut se suhstituer au silicium cnmne l'aluminium. Il entre dans la composition phnr.pholipidique des membranes cvtoplasmiques nt on sait que la cytotoxicité de la silice débute par le contact de la particule et d'une membrane, en particulier celle des lysosomes. 342 CONCLUSION L'étude rie la structure des composas aluminosiliciques naturals ou artificiels cnnduit a distinquer un état de surface propre au quartz, en l'occurrence, l'existence de vides dans le réseau tridimensionnel des tétraèdres SiO.. L'aluminium inhibiteur connu de l'action cytotoxique du quartz peut s'insérer dans le roseau cristallin a la place des atomes de silicium disparus. Il en résulte l'apparition de sites acides dénombrables, stables a l'épreuve thermique. Il ne s'agit donc pas d'un simple voile zénlithique de surface mais d'une substitution d'etomes d'alumi- nium en place de silicium dans le réseau cristallin préservé. On peut montrer que d'autres atomes comme le soufre et surtout le phosphore sont susceptibles de se comporter comme l'aluminium. Il n'est pas interdit de penser que le pouvoir cytotoxique des quartz pourrait être en repport avec la captation par le cristal d'atomes constitutifs de la membrane cellulaire. 3*3 Química de superficie v cicotoxicidad de la silice. E. Quinot, C. Cavelier, M. 0. Merceron (Francia) Los estudios excelentemente resumidos y completados por los investigadores del Centro de Estudios y de Investigación de Charbonnages de France han mostrado que el aluminio es experimentalmente un inhibidor de la nocividad pulmonar del cuarzo. El interés despertado por tales fenómenos de protección nos ha llevado a estudiar un método que permita fijar el aluminio en la estructura del cristal y a tratar de ver si otros átomos pueden desempeñar el mismo papel. El estudio de la estructura de los compuestos aluminosilfcicos naturales o artificiales lleva a distinguir un estado de superficie propio del cuarzo, o sea, en este caso, la existencia de vacíos en la red tridimensional de los tetraedros ICIO». El aluminio, conocido inhibidor de la acción citotóxica del cuarzo, puede introducirse en la red cristalina en lugar de los átomos de silicio desaparecidos. Ello acarrea la aparición de puntos ácidos numerables, térmicamente estables. No se trata pues de un simple velo zeolítico de superficie sino de una substitución del silicio por átomos de aluminio dentro de la red cristalina preservada. Puede mostrarse que otros átomos como el azufre y, sobre todo, el fósforo son capaces de comportarse como el aluminio. Hasta cabría pensar que el poder citotóxico de los cuarzos podría estar en relación con la captación por el cristal de átomos constitutivos de la membrana celular. La riqueza en puntos ácidos, térmicamente estables, descubiertos por contacto con el aluminio, sería entonces un factor de evaluación del poder citotóxico de las diferentes formas de cuarzo. 344 NEW ASPECTS IN THE ETIOPATHOGENESIS OF SILICOTIC AND ANTHRACOSILICOTIC LESIONS W. Weiler Pneumoconiosis Research Institute, Bochum, Federal Republic of Germany Introduction For experimental investigations on the effect of noxious dust the inhalation test, particularly the long-term inhalation test, certainly is the most appropriate method. In order to obtain more briefly comparable results injection tests, e.g. intratracheal tests or intraperitoneal tests, are frequently applied. The intra- tracheal test, however, raises some problems i the anaesthesia necessary for injections must not be too intense, permitting the animals to breath normally after injection. Shortly after waking up some of the animals expectorate part of the injected liquid. This leads to different initial values. Another problem is the very various distribution of dust quantities and the resulting pneumoconiotic modifications in the lung. It is important to know that various local dust concentrations result from these different distributions. An additional factor is the pathological lung modi- fications sometimes observed in rats, the animal species most frequently used for experimental purposes. These modifications are chronic respiratory diseases and alveolar lipoproteinosis. We therefore preferred to use the intraperitoneal test. In this test dust particles can distribute freely in the peritoneal cavity. Besides, a greater number of" organs for the evaluation of dust effects is at disposal. The test had the objective to define a quantitative measure 345 regarding the effect of quartz or coal-quartz-mixtures, respectively, dependent on dust dose, quartz proportion and test period. The intention was to use the obtained results as basis for the experimental test of coal mine dust containing relatively small amounts of quartz only. Methodology The tests were performed with female SPF-Wistar rats under SPF conditions (Weiler, 1972). The animals were treated by intra- peritoneal injections of 50 mg coal-quartz mixtures, the quartz proportion ranging from 1 to 75%. Further to the investigation of coal-quartz mixtures the isolated effect of the quartz quantities included in these mixtures was studied. For control and estimation purposes 2 animal groups received pure coal or pure quartz injections of 50 mg dust/animal. Each dust quantity was included in 1 ml physiological saline solution. The test duration was up to 6 months. On each examination date 5 animals of each group were examined. Results a) Quantitative measure for the effect of dust With higher quartz proportions (10 - 75%) the following organ weights showed a very good correlation to the quartz proportioni omentum, lien, cranial mesenteric lymph nodes and lung lymph nodes. Particularly the total omentum weight consisting of the actual omentum weight and of modifications outside the omentum as well as the total lymph node weight consisting of cranial mesenteric 346 lymph nodes and lung lymph nodes show a very good correlation to the quartz dose (figure l)t 9 3 0 -, d ' lo, ,1 ' »"""tum b) ToUt lymph n„J c: . mg 500 - i 400 300 200 100 0 0 0 5U 0 « 5 110) 37.5 25 12.5 mg Coil 12.5 25 37.5 m9 Quarts 1251 1501 1751 °U Ouarti in dust mistura O Coal -quarti mistura 0 Quartz only B B C M I only Control 45 37.5 5 1ZS 1101 125) 25 25 (501 Q Coal - quartz mistura B Q Quarti only B 12.5 mg Coal 375 mg Ouartl (751 •/. Ouarti In dust miiturt Coal only Control Fig. li Quantitative effect of coal-quartz mixtures compared to the corresponding quartz proportion after a 6-month test period. Intraperitoneal test, rats. at Weights of the total omentum (actual omentum and modifications outside the omentum, at the peritoneum). bi Weights of total lymph nodes (cranial mesenteric lymph nodes and lung lymph nodes). With small quartz proportions (1 - 8%) the weights for total omentum and total lymph nodes were likewise determined. Their dependence on the quartz content is shown in figure 2. 3^7 bl UWI t,muli noJc-i i i Total omentum 1,1 1,5 LO- 100- ft 5 \ 0 0 O <if>S V) <.8 <.; <,o mg Coil 05 1,0 2,0 3,0 ".,0 mg Quart; 11°/.) 12%) ( V U 141.1 18%) Quartz in dust m i i t u r t Coat • quartz mixtura B Coat o n t / 0 Quarti ont/ 0 0 O SO <,S>5 <.9 «9 1,7 <ii mg Coat 0 0,5 1.0 2,0 30 V 0 mg Quarti 11%) ( 2 % ) 14%) ( 6 % l 16%) Ouarti m dust mixtura Coat - quartz mixtura B Coat ont)r B Quartz only SO 0 • Control • Control Fig. 2: Quantitative effect of coal-quartz mixtures compared to the corresponding quartz quantities, 6' months test period. Intraperitoneal test, rats. a: total omentum weight b: total lymph node weight. It can be seen clearly that with small quartz proportions the total lymph node weight shows a better correlation to the dust or quartz proportion than the total omentum weight. Lien and liver show no dependence on the dust dose. From these results it may be summarised that the total lymph node weight consisting of cranial mesenteric lymph nodes and lung lymph nodes represents a sensible criterion regarding the quantitative effect of quartz or coal-quartz mixtures. The same observation could be made regarding the effect of very small quartz proportions. Thus, good conditions for the quantitative assessment of coal mine dusts are available. An addi- tional result of this study is the observation that the quanti- 348 tative effect depends on the quartz proportion only. b) Quantitative progression of contotic modifications It is of great practical importance to know the extent, de- pendent on dust composition and test period of the progression of coniotic modifications. After the total lymph node weights have proved to be a sensible quantitative criterion, this problem should be investigated in more detail considering the total lymph node weights. Based on these values a comparison between the effect of coal-quartz mixtures and of the corresponding pure quartz proportions, dependent on the test period, should be made. This may be best achieved by virtue of net weights, i.e. the weight of the coniotic modifications actually produced according to figure 3. Intraperitoneal test, rais Totti lymph node Ouartl injtctiort mg Coal qua mg 500 -n 500 50 mg «00 nttwttghts - ti nject on Quarti «00 - i - o 37.5 mg 300 - 200 N> 12.5 mg 100 - 0 - 12.5 mg 25 25 300 "^o 25. mg 200 Coal 37.5 mg "*o 5 1 1 ( 3 1 6 mg 12.5 mg 5 mg 100 - 1 1 9 12 Mon 0 mg mg - - r e i 3 1 6 37.5 mg «5 mg 1 9 Mon Fig. 3i Chronological process of quantitative reaction after intraperitoneal injections of quartz or coal-quartz mixtures. Net weights of total lymph nodes (cranial mesenteric lymph nodes and lung lymph nodes), intraperitoneal test, rats. 349 Apart from minor differences the curves for the coal-quartz mixtures and the pure quartz proportions of them are on the same level. This means that the quantitative reaction by coal addition does not change even if time dependence is taken into account. It may also be concluded that lymphotropism is not modified due to the coal proportion. Figure 3 shows for both groups that low quartz quantities or quartz proportions, respectively,cause a higher relative effect, measured according to quantitative modifications. This problem is discussed in detail in paragraph (c) t of this study. Regarding the progression of modifications it is important to note that, after a rapid increase of coniotic modifications during the first 3 months, both dust groups after a 6 month test period. showed the maximum Only after injections of 50 mg pure quartz the maximum is reached after 9 months. For the ratios studied with small quartz admixtures (1 - 8%) similar pairs of curves can be drawn. Here, however, the maximum quantitative reactions can be observed already after a 3-month test period. The most important result is that a certain quartz quantity has only a limited silicogenic potency and that there is no unlimited progression. c) Specific quantitative ouartz effect Figure 3 shows regarding quantitative modifications that the reaction to quartz is not linear. In addition to organ weight determinations, quartz quantity determinations by means of dust recovery from the organs were made for the test series with large quartz proportions (10 - 75%). According to the organ net weights consisting of the weight of the newly developed coniotic changes and the quartz proportion in the corresponding organs,the ratio 35o "mg net organ weight/1 mg quartz", i.e. the tissue quantity produced by 1 mg quartz, was defined and expressed as specific quantitative quartz effect. Table 1 includes the values for various organs obtained in the described way. mg organ net weight/1 mg SiCU Dust Coal Quartz (mf>) (mR) 45 37.5 25 12.5 - - 5 12.5 25 37.5 Omen- m tum Spleen (10%) (257.) (507.) (757.) 122 89 80 52 1724 1510 1390 127 48 47 56 2362 61 5 12.5 25 37.5 50 cranial mesenteric lvnroh nodes lung lymph nodes 616 397 466 236 359 370 379 362 850 682 670 606 255 207 160 593 342 274 591 238 189 879 263. Table li Net organ fresh weights in mg produced by 1 mg SiOo, in the listed organs of the individual test groups (net organ fresh weight = actual organ fresh weight - organ fresh weight of the coal control group for the coal-quartz series or - organ fresh weight of the normal control group for the pure quartz series). Rats, intraperitoneal test. 3 months test period. A very interesting aspect is the different reaction of various organs to certain quartz quantities. In this regard as well as regarding the orders of magnitude there are no differences between the coal-quartz series and the pure quartz series. Basical- ly, the examination of each organ listed shows comparative results, though on various levels. The supposed correlation according to the quantitative results indicating that small quartz quantities 551 are relatively more efficient, can be seen from the results in Table 1, except for the lung lymph node values in the coal-quartz series. In each presented organ small quartz quantities have a much greater specific effect. For the test series with higher quartz proportions (10 - 75%) the specific quantitative effect was defined first. From the organs of the test series with small quartz proportions (1 - 8%) no quartz was recovered so that precise value determinations regarding the specific quantitative reaction were impossible. In order to ob- tain a comparison between these two test series,the developed tissue modifications due to dust injections were correlated as net organ fresh weight to the injected quartz quantities or quartz proportions, respectively. This is feasible under the condition of a uniform dust distribution and a quartz concentration dependent on the total quartz quantity. Figure 4 presents the calcu- lated theoretical values for total lymph node weights. Specific quart? effect Total lymph nodes Organ net weight / 1 mg quartz — - • Qu„ti Co.I - Ou.rtl 352 Fig. 4« Specific quartz effect (mg net organ fresh weight/1 mg SiO ? ) correlated to the absolute quartz quantity. Intraperitoneal test, rats. 3 months' test period. Specific effect i theoretical calculation based on the set value of the quartz injection and the net organ fresh weight actually determined. Here and in previous cases a uniform relation for both test series can be observed. There is no substantial difference between the effect of quartz and the effect of coal-quartz mixtures. From this comparison it can be summarised that, as regards the quantitative effect, only quartz can be recognized as being the effective principle. It can also be inferred that the quantitative reaction to quartz is not linear. The principle of the decreasing specific quantitative effect correlated to the increasing total quartz quantity or quartz concentration, respectively, can be maintained for very small as well as for greater quartz quantities. Reference Weller, W. Long-term maintenance of SPF-rats under "clean conditions". Acta Pharmacol. Toxicol. 3_1, Supp. I, 1972. 353 Nuevos aspectos de la etiopatogénesis de las lesiones silicoticas v antracosilicoticas. W. Weiler (República Federal de Alemania) En el presente estudio se ha tratado de saber si la reacción coniótica depende exclusivamente del contenido en cuarzo o si puede modificarse por la adición de polvo de carbón. También se trataba de encontrar un parámetro cuantitativo correcto y más adecuado para evaluar la reacción a pequeñas cantidades de cuarzo, Además de la protección de cuarzo dentro del polvo total, había que estudiar la reacción cuantitativa y la duración de la prueba. En una prueba intraperitoneal de 12 meses con ratas, se estudió el efecto de la mezcla de polvos de carbón y de cuarzo. La porción de cuarzo iba de 1 a 75 por ciento. Además de estas mezclas, se estudiaron los efectos de las cantidades correspondientes de cuarzo puro. Los resultados de los experimentos permiten formular conclusiones respecto de los siguientes problemas « medida cuantitativa de las lesiones conióticasi características lineares de la reacción cuantitativa, según el contenido en cuarzo i progresión de las alteraciones según el contenido en cuarzo y duración de la prueba. Podría elaborarse un nuevo concepto de "reacción cuantitativa específica al cuarzo". 354 V MINERALÓGICA!, ANALYSIS OF LUNG DUSTS IN PNEUMOCONIOSIS WITH AN ANALYTICAL ELECTRON MICROSCOPE Hisato Hayashi Rsearch Institute of Undergound Resources, Mining College, Akita University, Akita 010, Japan Introduction In the past, there were no practical techniques available for performing microanalysis; consequently, the compositional determination of individual microparticles has been neglected. Now, the detection and analysis of tile--characteristic X-ray can be used to obtain qualitative and quantitative determination of chemical compositions in individual microparticles. There are two different types of X-ray spectrometry technique in conjunction with the electron beam excitation. One is the wavelength dispersive spectrometry (WDS), using analyzing crystals. Although this method has an excellent energy resolution, it is necessary for the surface of specimens to be flat. Moreover, this system requires high beam currents to produce sufficient X-ray emission to obtain good results. The analyzing crystal of this system must be varied on the Rawland circle geometry to make up one Bragg angle, and a spectrometer can detect the radiation of only one element at a time. Thus the whole procedure is rather tedious and time-consuming. Chemical analysis by energy dispersive spectrometry (EDS) is done by analyzing the primary or secondary Xrray emitted by the elements in a sample according to their energy rather than their wavelength, which is the procedure in traditional methods of X-ray analysis. The method differs basically from wavelength 355 dispersive spectrometry (WDS). It is possible to obtain and dis- play on an oscilloscope screen the full X-ray energy spectrum of an excited sample in a very short time, generally less than one minute, using a solid-state detector. Although the energy resolv- ing power is about 50 times poorer than WDS, a considerably small area can be analyzed by this system. Solid-state detectors have developed and their capabilities have improved considerably since they were first introduced. Today energy dispersive spectrometers are used widely as analytical tools and are attached to electron microprobes, scanning and transmission electron microscopes, X-ray fluorescence intruments and powder diffractometers. Recently a rapid and convenient procedure for semi-quantitative chemical analysis of asbestos fibers and clay minerals with an analytical electron microscope was proposed by the author and his co-workers (1978). This paper describes the technical details for the application of the above-mentioned procedure to the study of lung dusts in pneumoconiosis. Materials and Methods Lung specimens of two subjects with a clinically and histologically established diagnosis of asbestosis and silicosis were examined. As shown in Table 1, mineral compositions of the dust extracted from the lung tissues were previously studied in detail by several analytical methods, such as X-ray diffraction analysis, infrared absorption spectrometry and chemical analysis. Sections of lung 5_/jm thick were cut from ordinary paraffin blocks. After deparaffinizing in xylene, the sections were pre- 356 pared for examination in the analytical electron microscope by the carbon extraction technique. The analytical electron microscope used in this study consists of a transmission electron microscope (JEM-100 C ) , side entry goniometer (SEG), scanning attachment (ASID), and energy dispersive spectrometer (EDS). Ultrastructures and sizes of materials are clearly detected on both the conventional transmission electron microscope (TEM) image and scanning transmission electron microscope (STEM) image. The selected area electron diffraction (SAED) pattern is easily obtained from a microarea on the subject using the SEG, and the chemical composition of the same area can also be analyzed by the ASID and the EDS which is smaller than 200  in size. This procedure can be carried out without any realignment of the electron microscope. The isolated particles in the specimens on an electron microscope grid were selected on the STEM image. After taking the photograph, they were examined by SAED, and then were analyzed using the EDS. The time required for measuring the X-ray intensity was 100 to 200 seconds per position. The average values of peak intensity and background intensity were determined from 5 to 10 measurements. Chemical compositions of lung dusts were analyzed quantitatively using the technique proposed by Hayashi et al (1978). Results and Discussion Several random areas were analyzed from the lungs of 2 patients with pneumoconiosis. The identity of the mineral fibers and 357 particulate materials detected in the specimens was based upon both the crystal structural analysis and the chemical analysis of the various fibers and particulate analyzed. Fig. 1 shows a STEM image and the EDS spectra of particles extracted from the lung with asbestosis. Particles 1 and 2 in Fig. 1 show a characteristic spectrum of talc. Similarly, a typical spectrum of actinolite, an amphibole type of asbestos, is shown in Fig. 1. X-ray diffraction analyses of the mineral residue from this lung tissue had already been studied, and indicated that the mineral compositions of the lung dusts in this patient were talc, quartz, illite, chrysotile and amphibole asbestos. In Fig. 2 particles extracted from the silicotic lung specimen can be seen. in Fig. 2. The analysis of these particles is also given It was determined by using the energy dispersive detector, and shows a characteristic spectrum for pyrophyllite (particle 2), kaolin (particle 3), illite (particle 13), and quartz (particles 11 and 12). The X-ray diffraction analysis and infrared analysis of these lung dusts had been examined previously and revealed that there were quartz, trydimite, cristobalite, pyrophyllite and kaolin in the mineral residue extracted from the silicotic lung of a refractory worker, Most of the minerals detected by X-ray diffraction analysis were identified, and their chemical compositions were estimated by the analytical electron microscope. Thus, the analytical electron microscope can be used to detect the morphological, structural and chemical characteristics of individual particulates in lung dust. 358 Recently Hayashi et al (1978) proposed a rapid and convenient procedure for seml-quantltatlve analysis by using an analytical electron microscope» This procedure applies to the chemical analysis of Individual particles extracted from lungs with asbestosis and silicosis. The values of K for talc, illlte (mica), kaolin mineral and pyrophyllite are obtained after substractlng the water content from the ideal compositions of these minerals. The K values of talc, illlte (mica), kaolin mineral and pyrophyllite are 95.2, 95.5, 86.0, and 95.0, respectively. In the same way, the K value of actinolite is obtained from data of actinolite, Chester, Vermont (Weeks, 1956). The results obtained from the study of dusts extracted from lungs with asbestosis and Table 3. silicosis are given In Table 2 and It can be seen In these tables that the EDS data of Individual minerals extracted from lung tissues are In comparatively good agreement with the ideal compositions of each mineral. Furthermore, this technique permitted to identify and determine some other minerals which could not be detected by X-ray diffraction analysis. The sensitivity of the X-ray diffraction analysis for the detection of a small amount of a particular mineral In a mixture depends a great deal on the mineral concerned. A well crystallized mineral can often be detected at below the 1% level, whereas quite large concentrations of a poorly crystallized mineral cannot be detected. Nevertheless, the studies using analytical electron microscopy have been successful In Identifying minerals In the lungs. A mineral can be said to be "determined" when we have identified the crystal phase and have determined its chemical 359 composition. These two kinds of information about a mineral may be sought by several techniques. Today, these two informations are obtained by the analytical electron microscope. This micro- scope has been developed for facilitating observations by the transmission electron microscope, energy dispersive microanalysis and selected area electron diffraction on the same microarea in the specimen by instantaneous commutation. Moreover, by applying the procedure of semi-quantitative chemical analysis with the analytical electron microscope, the chemical composition of individual particles extracted from lung tissues with asbestosis and silicosis can be determined together with their crystal phase, This technique may contribute to obtain valuable information about the relationship between lung dust and lung pathology in pneumoconiosis, References Hayashi, H., Aita, S., and Suzuki, M. (1978) Clays and Clay Minerals, 26, 181. Weeks, W. F. (1956) Journ. Geol., 64, 456. 36o 3ju e« aa.ai Fig. 1. co Er* ao.Oi Ct aaoE toon STEM image and EDS spectra of particulate materials extracted from a lung with asbestos is. 361 \ KCa Fe »r. OD.Ol C, aoD-têoi* Fig. 2. STEM Image and EDS spectra of particulate materials extracted from a lung with silicosis. 362 i. o **-o O) ¿£ í. O V) s B 01 •M C Ol +1 IO t - o e o T3 IO VI m c e •M VI 3 •o ai -* o i- e S • 1 — VI t. (Q ai ai ^* >> •S ai in a . ro 4-1 stry ths t- ai 3 -o c E •o e IO •M C VI iIO ai ai S >> m a. w >> L. O +J V IO l< * • ai i- ,pc ~ " ite o u •¡J O •M VI >a> 0) r— 0i •^ +> o B 3 rH ß •A m u •o m i-H (0 ner IO di 01 •H VI e •o •«-> >> C <_> ai 1, TJ A "3 j= a. •-* o IO 5 (- m o JS •P t - 3 01 Q ai m .u a •u 0 e IO u 01 ai O fc. ai 4-1 *J ai N 4J 110 3 ex •»1> -IO JD N» o •M I10 3 r— =» •^ - J> Q. o •^ R> JC S Ol •H ai Í •o c «a •w VI i- cr u lungs •d a 4-> B O id • (0 3 n) U o t. o ja 3 O O VI VI O 4-> VI VI ai VI XI vi IO o u •o r— e IO Vi ¡E X 01 CM ai 0> <o m 0) U] 0> 111 id u cosi s < stosi s E-" Ol JO r— w l/l < 365 >> Table 2. Minar«1« Actinollta Talc Results of EDS analysis of p a r t i c u l a t e materials extracted from the lung with asbestosis Spaciaan Mo. 6 7 810j total Iron MgO 18.79 20.40 19.60 20.41 A1 CaO Avaraga Chaatar 53.80 58.71 56.25 55.26 9.05 4.79 6.92 6.30 11 63.29 1.98 28.43 - 4 3 5 1 2 65.06 65.38 65.62 65.93 67.57 65.48 63.5 1.02 1,08 0.86 0.82 29.12 29.81 29.57 28,17 26.76 28.64 31.7 - 41.37 47.04 51.74 46.71 1.61 10.04 5.44 5.70 5.73 1.91 2°3 16.00 13.74 14.87 12.07 2.23 *2° 0.10 oth «r* total 97.64 97.64 97.64 1.27 97.64 H20 a otnera Total 2.12 99.76 1.49 95.19 (ilo,) Avaraga Idaal Comp. Illita 8 10 9 Avaraga Idaal Camp. 45.2 1.43 0.48 95.20 95.19 95.19 95.18 95.19 0.25 95.19 95.2 34.29 20.08 30.57 28.32 18.23 95.50 12.62 95.50 3.86 2.43 95.47 11.58 0.80 95.50 38.5 11.8 364 95.5 4.8 100.0 4.5 100.0 Table 3. Results of EDS analysis of particulate materials extracted from the lung with silicosis. UMItlt •patüMB M. !K~- 2 Uolla S5.U M,0 Mt«l 2.51 3.25 95.00 1.S0 2.13 1.72 •6.5 39.5 ca.ll «1.76 «.16 «.51 19.56 23.75 S2.66 25.32 1.06 0.55 10 95.0 1.15 «.» COI 2.95 31.« (3.76 63.5 ••• faul 5.0 100.0 lt.O 100.0 «.5 100.0 «.1 100.0 K.0D •6.0 2.79 10.97 se.5 •5.2 UMI 9.0« 9.00 15.3« 11. U 95.50 95.« 95.» 95.« 11.1 95.5 95.20 31.7 95.2 COM.. 9.5« 76.« I ; ».16 96.33 51.75 5 IS 11 12 a •llvary nmtêl «,0 6.65 1 U N I llMTIl C*0 2.17 21.3 Cav- OMrti utal 23.07 «0.50 « S":"**" Mao «i,o, 35.75 u Cálelas •lllcat« l.<8 ) ft*«ra«* Tat« tio UHI IdMl Ml« •IO, InitMi •o. e 6.02 13.(2 5.U 0.69 99.99 1,58 c i - t . n 99.98 100.00 1.25 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 • 10, !.«J 100.00 "•» • ci «.55 6.51 1.01 -i twal 77.(5 100.0 365 — Análisis mineralógico de los polvos en el pulmón en los casos de neumoconiosis. con un microscopio electrónico analítico« H. Hayashi (Japón) El microscopio electrónico analítico se compone de un microscopio a transmisión electrónico, de un goniómetro lateral con entrada lateral, de un accesorio de exploración y de un espectrómetro radiológico dispersor de energía. Los autores han propuesto recientemente un procedimiento rápido y sencillo para el análisis químico semicuantitativo de las fibras de amianto y minerales arcillosos con el microscopio electrónico analítico. Con este procedimiento fue posible descrubir las características morfológicas, estructurales y químicas de cada material particulado por separado presentes en los pulmones sin necesidad de ajustar cada vez el objetivo. Se han estudiado los materiales particulados presentes en los pulmones con neumoconiosis tales como la asbestosis, talcosis, pirofilitosis, silicosis y neumoconiosis de polvos mezclados. Los resultados de la dispersión de energía en cuanto a la composición mirrerai de esos materiales particulados son similares a los obtenidos por difracción por rayos X en los polvos extraídos de los mismos tejidos pulmonares. Además, los resultados de dispersión de energía de cada material particulado coinciden con la exposición química de algunos anfiboles asbestiforraes y los del talco ideal, la pirofilita, caolinita y la ilita. Los estudios indican claramente las vastas posibilidades del microscopio electrónico analítico para determinar la composición química de las partículas finas, a la vez cualitativa y cuantitativamente. 366 T. N D 1 C r I S r S S T P N V ro.f-SDinoza Reporter II Gunnar Mouie". , Egli Pphus., and fljorn Gylseth. , Asbestos fibre content In Idling tissue In relation to Asbestos exposure and causes of death. III N.V.Vallyathan. , and JoNn r.Craighead Silica dust-aS90ciated pulmonary lesions in granite workers lacking Radiologic evidence of disease. IV J.A.Dick. The role of pulmonary tuberculosis In the causation of progressive massive fibrosis in coal workers in great britain V Tee L.Guldotti. The higher oxides of nitrogen: A role In altering pulmonary response to injury? VI J.Ro9manith., R.Leonardi., D.PrsJ9nar., H.Breining and III.Ehm. The effect of the combined application of cadmiun and lead sulfide and côal dust of the development of lung fibrosis in rats. VII D.PraJsna3., H.Breining., and J.Rosmanith. Lung fibrosis In rats 8fter lead sulfide application. VIII H.Breinning., J.Rosmanith and D.PraJsnar. Lung fibrosis In rat9 after cadmiun sulfide application. 367 NEUMOCONIOSIS EN EL PERU Dr. Mario A. Espinoza M. Lima •• Peril Los conocimientos científicos sobre los efectos dañinos de los polvos inorgánicos que causan las Neumoconiosis son de época reciente. Sin embargo, se sabe que Plinio el Viejo, Hipaorates, Celso, Agrícola, Paracelso y otros habrían observado y descrito mucho antes los efectos dañinos del polvo en los pulmones. Estudios anatomopatológicos realizados por Diemerbrock en 1649 demostraron los efectos antes señalados por los hallazgos de fibrosis, enfisema y depósito de polvo en el tejido pulmonar examinado. Ramazzini en 1700, considerado como el padre de la Medicina del Trabajo por sus brillantes observaciones clínicas en este campo, describió también los efectos dañinos de dicho elemento sobre el aparato respiratorio, muchos de ellos con efectos fatales. Zenker fue el creador del término de Neumoconiosis y Kussmaul demostré químicamente el efecto dañino del sílice libre, siendo Visconti quién estableció el término de Silicosis. Collis en 1915 haciendo una revisión de los conocimientos sobre Neumoconiosis estableció la teoría del sílice libre como responsable de la enfermedad, haciendo notar sobre la gran susceptibilidad de los enfermos de Silicosis a la Tuberculosis. Gadner y Cummings de los Laboratorios de Saranac Lake realizaron estudios sobre la patología pulmonar en los trabajadores de minas de hierro en Michigan y Wisconsin en los Estados Unidos, obteniendo interesantes resultados y llegando a la conclusión que la incidencia de patología pulmonar estaba en razón directa con la exposición a polvos de cuarzo que como se sabe contiene alto porcentaje de sílice libre. En el Peni estudios sistemáticos sobre Neunoconiosis fueron hechos a partir de 1948 cuando se creó el Departamento Nacional de Higiene Industrial, hoy Instituto de Salud Ocupacional. En Enero de 1935 dicha enfermedad fue declarada enfermedad profesional sujeta a indemnización. Conviene señalar que el término de Neumoconiosis se viene utilizando en algunos países como sinónimo de Silicosis, a pesar de que aquél es un termino genérico que agrupa a todas las entidades nosológicas causadas por el polvo, en tanto que Silicosis es una Neumoconiosis Específica, entidad anátomo clínica, bien definida. 369 En la Cuarta Conferencia Internacional de Neuinoconioais llevada a cabo en Bucarest en Octubre de 1971, organizada por la Oficina Internacional del Trabajo (OIT), se definii la Neumoconiosis como la acumulación de polvo en los pulmones y la reacción del tejido en presencia de este material, definición simple que prácticamente restablece la definición dada por Zenkor. Entre las diversas Neumoconiosis, la Silicosis y la Asbestosis son las que causan "incapacidad" para el trabajo, mientras que la siderosis, la antracosis, la baritosis, la estañosis y otras causarían alteraciones mínimas del tejido pulmonar con merma igualmente leve de la capacidad física para el trabajo. Por eso las dos primeras suelen ser llamadas "Neumoconiosis Específicas" y las ultimas, "Inespecíficas". La Beriliosis, neumopatía severa que se presenta entre los que trabajan con sulfato de berilio es considerada,como una Neumoconiosis. La Bisinosis, la bagazosis y la tabacosis han sido señaladas como causantes de procesos alérgicos pulmonares. Los ingleses consideran a la antracosis como una Neumoconiosis incapacitante, debido al enfisema que provoca, hecho que es discutido por algunos investigadores. Nosotros hemos encontrado muchos casos de antraco-silicosis en los que trabajan en minas de carbón, creemos que en este caso los trastornos anatomo patológicos son debidos al sílice libre más que a las partículas de carbón inhaladas, porquelas minas son de un alto poder silicógeno. Los conocimientos actuales sobre Neumoconiosis están basados generalmente en las investigaciones epidemiológicas sobre dicha enfermedad cuyos resultados han permitido comprender e interpretar la relación que existe entre el agente (polvo), el ambiente (lugar de trabajo) y el huésped (trabajador)i Por esto; será motivo de un análisis breve cada una de estos factores para poder comprender las características epidemiológicas de las Neumoconiosis,principalmente de la Silicosis en el Pení, país eminentemente minero cuyos trabajadores que a pesar de no ser muy numerosos contribuyen con más del 50$ de los ingresos de divisas para el país. Características del Huésped El minero peruano por lo general realiza inicialmente trabajos mineros, además labores agrícolas. El minero permanente resulta después de muchos intentos de mantener este estatus de trabajo. 37o Como la mayoría de los centros mineros están situados en lugares superiores a los 3,000 metros sobre el nivel del mar, es comprensible que los trabajadores sean personas que habitan en la sierri o en lugares circunvecinos, cuyas características antropométricas corresponden al hombre andino, descrito por Monge y Hurtado, en el Instituto de Biología Andina del Peru. Edad Los trabajos mineros por su naturaleza, requieren de hombres sanos y resistentes, la edad mínima establecida por la legislación peruana para realizar labores mineras, es 18 años. Algunos autores consideraban que los jóvenes serían mas susceptibles de contraer Neumoconiosis, pero estudios efectuados por el Instituto de Salud Ocupacional han demostrado que la mayor prevalencia de Silicosis en este grupo otario, era debido a que estaban expuestos a altas concentraciones de polvos que contienen sílice libre. El estudio referido ha demostrado casos de Silicosis temporana entre los trabajadores cuya edad estaba comprendido entre los 20 y 24 años. Las ocupaciones que desempeñaban eran las más expuestas al polvo, como las de perforistas, ayudantes y enraaderadores. El estudio en referencia demostró que de 2,152 trabajadores expuestos a polvos que contienen sílice libre, 212 o sea el 98,5 por mil, adolecían de Silicosis, observándose que la provalencia de dicha dolencia aumentaba paralelamente a la edad incrementándose de 9.1 por mil en el grupo de 20-24 años a 353 por mil en el grupo de 60 o más años, lo que demostraría lógicamente que el tiempo de exposición (riesgo) se prolonga cuanto más es la edad del trabajador. Tabla No. 1 Analizando los casos de Silicosis en relación con el grado de evolución se ve una relación directa entre tiempo de exposición y grado de evolución de la enfermedad en los dos primeros estudios SI y SII, no así en el tercer estudio (SUI), pues es de suponer que en este período de evolución de la enfermedad, los obreros abandonan el trabajo tanto por su edad, oomo por los efectos de la enfermedad que le impide realizar trabajos que requieren gran esfuerzo físico, esto explicaría el hecho de que en el grupo de edad, mayores de 60 años se encontró sólo 6 casos do Silicosis. En cuanto a la SÍlico Tuberculosis, se observa un hecho importante en relación a la edad del trabajador afecto de Silicosis y es que hay una mayor incidencia de complicación cuanto más avanzado es el grado de Silicosis. 371 Raza Las afirmaciones hechas sobre la influencia de la raza en relación con la patogenia de la enfermedad no es un hecho comprobado ; la existencia de una mayor prevalencia de Silicosis entre una determinada raza se debe principalmente a que están mayormente expuestos al agente como ocurrid en Sud Africa a cuyos trabajadores negros se les asignaban los trabajos en lugares con mayor concentración de polvo. Nosotros no hemos encontrado ni observado una mayor predisposición ni en los naturales de la región ni en la raza mestiza, pues ambas son igualmente susceptibles. Sexo La mayoría de trabajadores en lugares polvorientos son del sexo masculino sin embargo, es digno de mencionar quealguas mujeres puedensufrir de Neumoconiosis (Silicosis) cuando trabajan envasando detergentes domésticos como el sapoli u otros similares, en cuya fabricación se emplean además del jabón,un material abrasivo como la tierra de infusorios. La bisinosis es frecuente observar en las cardadoras en la industria textil. Afecciones del tracto respiratorio superior y de los pulmones. Ciertas alteraciones bronco pulmonares y de las vías respiratorias superiores pueden ser causa de una mayor predisposición para adquirir la enfermedad. Es sabido que las personas que sufren de dsma bronquial, bronquitis crónica, desviación del tabique nasal tienen mayor riesgo de trabajar expuestos a polvo por lo que debo evitarse asignarles trabajos en lugares polvorientos. Susceptibilidad Individual Aunque no está plenamente comprobado, ciertas observaoiones clínicas permiten juzgar que unos individuos son más propensos que otros a contraer esta enfermedad. Así es como de un grupo de trabajadores quo laboran en las mismas condiciones ambientales expuestas a los mismos elementos contaminantes, unos adquieren la enfermedad, mientras que otros no la sufren, este hecho se explicaría considerando el papel que juega la susceptibilidad individual. 372 Características del Agente Debemos señalar lo siguiente: a) La composición de polvo. b) La concentración de las partículas. c) El tamaño de las mismas y finalmente d) El tiempo de exposición Es un hecho comprobado que la Silicosis es debida a la inhalación de polvos que contienen sílice libre, las observaciones clínicas y experimentales lo han demostrado así. Los trabajadores experimentales de Gye y Kettle empleando sílice coloidal ha permitido observar la proliferación de tejido fibroso. Gardner ha producido las mismas alteraciones en animales, en un periodo corto de dos años, sometiéndolos a altas concentraciones de polvos de sílice. Estos trabajos y otros permiten pensar que la sílice actúa principalmente por acción química o inmunológiea y no por acción mecánica como se creía anteriormente, La exposición de animales de experimentación a polvos de diamante, carborundo y otros qua oon más duros que la sílice corroborarían esta tesis ya que el efecto no ha pasado de ser simplemente irritativo local. La patogenia de la Silicosis sigue siendo aun desconocida, la teoría química es muy discutida frente a los trabajos recientes desarrollados en el campo de la inmunología y los estudios histoquímicoo de los componentes del nodulo silicótico. Los pacientes estudiados realizados por Deny, Irwin y Robson utilizando el aluminio con fines profilácticos y terapéuticos, no han alcanzado los frutos que se esperaban. Concentración de Partículas La concentración de partículas de polvo en el ambiente de trabajo juega gran papel en la etiopatogenia de la Silicosis, es por eso que se han fijado en las industrias polvorientas ciertos límites denominados "Concentraciones Máximas Permisibles" cuyos valores han sido establecidos, teniendo en cuenta el contenido de sílice libre, así polvos con un contenido mayor de 50f° de sílice libre se considera permisible hasta cinco millones de partículas por pie cúbico de aire; de 5 a 50$ veinte millones y por debajo de 5$ cincuenta millones. 373 Se ha' obtenido una utilidad muy práctica de esto3 estudios, aplicables a la patogenia y a la prevención de la Silicosis en relación a la concentración de partículas de polvo, puás para desarrollarse la enfermedad, la sílice debe estar presente en una concentración tal, con uncontenido de BÍlice elevado y depositarse en los pulmones en cantidad suficiente. A bajas concentraciones de polvo, el peligro sería mínimo, a pesar de una exposición prolongada. En esto está basado el concepto de "Concentración Máxima Permisible", cuyos valores varían de acuerdo con la clase del contaminante atmosfèrico. Dichos valoreB han sido establecidos para trabajos a nivel del mar, por lo que en el Peni tendrían valor relativo por que juegan además, otros factores condicionados por la altura a que están situados los centros mineros. El análisis estadístico de los datos obtenidos en ira estudios realizados, nos permitirá establecer dichos límites. • Otros factores tales como la temperatura, humedad, ventilación, etc. influyen sobre la dinámica biofísicas de las partículas de polvo. Tamaño de las Partículas En cuanto al tamaño de las partículas sabemos que las de tres mieras o menores ganan fácilmente el nivel alveolar venciendo los obstáculos que presenta el tracto respiratorio superior. Las partículas de 10 mieras cúbicas o mayores precipitan fácilmente y si Bon inhaladas son detenidas por el filtro naeal y el epitelio ciliado del tracto superior siendo expulsadas con la expectoración mediante la tos; en tanto que, las más pequeñas además de franquear fácilmente dichas barreras, permanecen an-, suspensión mucho tiempo en el ambiente de trabajo, con el peligro de ser inhaladas. Estudios llevados a cabo por Hatch, hemdon, Landahl y otros sobre retención o depósito de polvo inorgánico a nivel del sistema respiratorio en relación al tamaño de las partículas han demostrado que el porcentaje de retención disminuye de cerca de 100$ parapartículas mayores de 5 micrones a cerca de 25% para partículas de 1/4 de miera, El tamaño de las partículas suspendidas en el ambiente de trabajo en las minas peruanas en promedio variaban entre 1 y 3 mieras cúbicas en un alto porcentaje. Tiempo de Exposición El tiempo de exposición como factor en la patogenia de la Silicosis, por esto es importante establecer claramente mediante una 37* historia ocupacional bien tomada, si la exposición a material particulado fue prolongada y continua o esporádica, el análisis ocupacional de 11,942 historias clínicas de trabajadores mineros, QO los que 4,331 habían laborado exclusivamente en subsuelo y 7,611 en subsuelo y superficie, se encontró 461 trabajadores 10.6 pormil de casos de Silicosis en el primer grupo y 560 73.6 por mil en el grupo mixto, Los casos de Silicosis diagnosticados en trabajadores fuera de las galerías, tienen antecedentes de haber trabajado en labores de subsuelo. El tiempo promedio de exposición para adquirir Silicosis en primer grado de evolución fue 9.7 años; para el segundo grado 10.9 años y para el tercer grado 13.4 años, tiempos de exposición relativamente cortos que traducen un ambiente insalubre de un gran valor epidemiológico para realizar acciones de prevención. Merece subrayar que mientras en los estudios llevados a cabo en el mismo centro de trabajo el tiempo de exposición guarda relación directa en el grado de evolución de la enfermedad, los datos obtenidos en el Departamento de Exámenes Médico-Periciales de Lima son variables hasta cierto punto contradictorios como puede verse en la Tabla No. 2, Resulta que siendo el tiempo promedio de exposición para el primer grado 10.8 años, para el segundo grado fue de 9.4 años, lógicamente el tiempo debería ser mayor, tal discrepancia se explicaría teniendo en cuenta que, los datos o CU p ac i 0 nales referidos por los trabajadores fueron inexactos. Habría que admitir en este caso que los reclamantes de indemnización no refieren una historia veraz, omitiendo tiempos de trabajos en otras compañías mineras, sabiendo que en caso de sufrir de enfermedad ocupacional será responsable del pagoÉ de la indemnización la ultima empresa que le tuvo a su servicio. En la actualidad el pago de la Indemnización está a cargo del Seguro contra Enfermedades y Accidentes del Trabajo. Caracteres del Ambiente Cada vez más la Ecología cobra actualidad, el concepto ecológico de salud y enfermedad en el campo de la Salud Ocupacional, es muy importante ya que juega un papel preponderante el ambiente de trabajo, especialmente en la patogenia de las Neumoconiosis. Dijimos que las minas en el Peni están situadas en lugares que sobrepasan los 3,000 metros sobre el nivel del mar, en los que la demanda de oxígeno durante el esfuerzo físico es mayor, debido a la bajo presión barométrica. Las minas en su mayoría son subterráneas, la perforación, voladura y otras actividados permiten la dispersión del polvo en suspensión, aumentando cuando estas 375 operaciones se hacen en seco. La falta de ventilación, las galerías estrechas y los turnos de trabajo continuos no permiten en muchas minas la dispersión del polvo que gañeran el mal. Las limitadas facilidades de bienestar de que disponen los trabajadores, especialmente en las pequeñas y medianas empresas, la deficiente nutrición, el alcoholismo y la costumbre ancestral de masticar hojas de coca, moman la ealud del trabajador minero haciendo propicia el terreno para contraer enfermedades de diversos orígenes especialmente la Neumoconiosis. Los centros mineros del Perú, alejados de las poblaciones con facilidades sanitarias constituyen verdaderos oasis poblacionales donde es posible hacer estudios epidemiológicos aplicando la Epidemiología Geográfica y principalmente desde el punto de vista Ecológico. Silicosis y Altura El Perú productor de cobre, plata, plomo y otros minerales afrontan con la acción adversa de la altura sobre la salud de sus trabajadores. Estudios llevados a cabo por el Instituto de Salud Ocupacional al respecto han-demostrado que existe una correlación entre Silicosis y altura, siendo mayor su prevalencía cuanto mayor es la altura, especialmente sobre los 4,000 metros sobre el nivel del mar. En el estudio efectuado en 32,498 trabajadores mineros se ha encontrado que las tasas de Silicosis suben progresivamente de 4.2$ a los 1,000 metros Bobre el nivel del mar a 61. 2# entre los 40001 - 5000 metroB de altura. Tabla No. 3. La patogenia no está aun clara, pero se puede admitir que el hombre de altura moviliza una mayor cantidad de aire para captar la cantidad necesaria de oxígeno en comparación con los trabajadores de la costa, debido a la baja presión barométrica. Este estado de hipoxia en el que vive y trabaja, hace que la cantidad de hemoglobina y los hematíes se incrementen notablemente dando una mayor densidad a la sangre y obligando al corazón a un mayor trabajo, siendo la velocidad circulatoria más lenta, todo ello causaría el fenómeno de lo que Monge del Peni llama encharcamiento, que a su juicio favorecía la presentación de Silicosis en un tiempo menor al que se presentaría en los trabajadores de la costa. En el Cuadro No. 1 se hace un resumen de los factores patogénicos de la Silicosis, que han sido estudiados en cuatro minas de cobre, situadas a diferentes niveles de altura sobre el nivel del mar. En las minas A,B,C y D, como se puede ver en la; Tabla se han encontrado diferentes concentraciones de polvo en el ambiente, siendo el más alto en la Mina C, un contenido de sílice libre igualmente alto, con una incidencia de 8.4$ de Silicosis en un tiempo de exposición relativamente corto de 8.7 años. 376 Dmmor—o>u"vO'"">r— &î Or-tC\lrO00lT\rHO^»f^H i - I H rH r n n | O H H ' Í ' Í I M H O H O U ,-H C i O H P4 ' * Sfl O Ooo ITM-OCO O i n o O OOiOwwnwnoo OOCOCMC-OOt—Om ¿f m • • • « • • • • • • CcomC^cMO-ciicMOvo H CM rr>rr\\o t— O t— H CM H OCM C—CT>t ^ f - O «d-VO f»! 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XI •*)-. ir» H EH •3 00 vo O •-5 Sw SMO <J >H g co H 802 t'en H 8 710 8 S g co CTl 70. • CM .378 in ir\ • 10. rn r-l rH M o -O t o Ss H 177 <i¡ o EH M CM rn •* in cd o ri et) PH O H O O PO H O O •sa- Q o u H CM 0) P O o CO 379 CU « cci O CUADRO No. 1 RELACIÓN ENTRE SILICOSIS Y FACTORES AMBIENTALES LIMA - PERU MINA A B C Concentración (millones por p i e cúbico) 10.0 26.1 58.0 23.0 «5 de SÌO2 9.6 a 34.2 15 15,3 a 67.0 27 Promedio tamaño de partículas * (Me) 1.3 1.0 1.3 1.3 Tiempo promedio de exposición (en años) 12.1 8.0 8.7 13.6 0.3 16.0 8.4 13.7 Silicosis * Mieras ciíbicas 38o PATOGENIA DE LAS NEUMOCONIOSIS Dr. Mario Espinoza M. Lima - Peru Estudios llevados a cabo por el Instituto de Salud Ocupacional del Perú han demostrado que existen en el país diversos tipos de neumoconiosis, siendo los más importantes la sx licosis y la antraco silicosis. Se ha demostrado a través de los exámenes médicos realiz¿ dos en más de ¿0.000 trabajadores mineros y de estudios del medio ambiente de trabajo, la existencia de una relación muy estrecha entre la concentración de polvo en el ambiente de trabajo, contenido de sílice libre, tamaño de las partículas, tiempo de exposición y neumoconiosis. Que en el caso del Perú existe además, un factor muy impor, tante, que es la altura. La mayoría de las minas están situa das sobre los 3,500 metros sobre el nivel del mar donde la presión atmosférica es menor, lo que obliga al trabajador a una mayor movilización de aire durante la fase inspiratoria para captar la cantidad de 0 2 necesario que demanda el esfuej: zo físico generado por el trabajo, hecho que no sucede a ni vel del mar. Estos hechos y otros referidos a las características antro pométricas del hombre andino han sido estudiados por Monge, Hurtado y otros en el Instituto de Biología Andina del Perú. Siendo la respiración más lenta y profunda en la altura hay que admitir que el depósito de partículas en el aparato respiratorio sea mayor, lo que favorece la presentación de neumoco niosis en un tiempo corto. Anualmente, estudios realizados por el Instituto de Salud Ocupacional del Perú sobre la aplicación de "Concentración Máx^ 381 2. ma Permisible" establecida por los Higienistas Industriales con relación al polvo ambiental para el control de las Neumoconiosis no es aplicable para niveles superiores a los 3.000 metros, porque se presentan casos de silicosis, aún por debajo de dichos valores. 382 ASBESTOS FIBRE CONTENT IN LUNG TISSUE IN RELATION TO ASBESTOS EXPOSURE AND CAUSES OF DEATH Gunnar Mowé, Egli Ophus, and Bj(5rn Gylseth, Institute of Occupational Health, Oslo, Norway INTRODUCTION Knowledge on the relationship between occupational asbestos exposure, asbestos lung burden and different asbestos related diseases is important for the evaluation of the health risk of individual workers. Evaluation of the occupational exposure should include information on type of asbestos, intensity and duration of the exposure and the lapsed period from onset of exposure. Furthermore, other possible exposures should be record- ed as well. Several authors have determined the fibre concentration in lung tissue using different microscopic techniques (1,2,10). Lung tissue from persons who have died of asbestosis, mesothelioma and bronchial cancer has been studied in detail in order to obtain an indicator of the asbestos lung burden. Electron micro- scopes fitted with an energy dispersive x-ray analyser have proved to be valuable for the quantification and identification of asbestos fibres in lung tissue (7). The aim of the present investigation has been to study the relationship between occupational exposure and asbestos lung burden in different asbestos-related diseases. MATERIAL AND METHODS The fibre concentration in lung tissue samples obtained at autopsy was determined by scanning electron microscopy (SEM). Before the SEM investigation the samples were dried at 80°C for 385 48 hours and ashed in a low temperature plasma asher. The fibres were identified by morphological criteria and by energy dispersive x-ray microanalysis. Detailed methods will be described elsewhere (3). The material consists of samples of 23 cases which have been classified into 3 exposure groups according to their occupational histories. Group I (high exposure) consists of 7 insulation workers who have been exposed to both crocidolite and chrysotile asbestos. The exposure has been severe for some of them, and they have certainly been exposed to man-made mineral fibres as well. During insulation work in refrigerator ships and plants, exposure to cork dust and tar fumes also has occurred. Group II (low exposure) consists of 3 workers who have been slightly exposed during handling and transport of asbestos products, but they have never been doing insulation work. Group III consists of 13 persons with various occupa- tions without known occupational asbestos exposure. Information on the occupational history was obtained from several sources i The trade union of insulation workers, different insurance files and through interviews with insulation workers who participated in a recent epidemiological investigation. RESULTS In Group I the age at onset of exposure and the duration of exposure show great variations. 1. These results are given in table The lapsed period from onset of exposure until death is very long and rather constant. The results in table 2 are presented as number of fibres per 381 gram of dry tissue. The fibre concentration in the lung tissue and the proportion of fibres with positive asbestos identification are higher in group I than in group II and III. Lung tissue in group I contained (2,2 - 36) • 10 6 , group II (0,3 - 2,4) • 10 6 , and group III (0,3 - 1,5) " 10 respectively. fibres per gram of dry tissue , The proportion of fibres with positive asbestos identification in group I was 79%, in group II 60%, and in group III 23%, respectively. Table 3 shows the number of coated fibres in relation to the total fibre concentration. are coated. In group I only 9,6% of the fibres Most fibres are shorter than 5jjm and thinner than Lum. Table 4 shows the fibre concentration in relation to causes of death. The highest fibre concentration is found in the pleural mesothelioma cases, in one of which asbestosis occurred. The fibre concentration in cases with asbestosis varies from (8,7 36,0) • 10 fibres per gram of dry tissue. Owing to the small sample it is impossible to determine the relationship between fibre concentration and degree of lung fibrosis. In one worker who died of mesothelioma (case No.2), 12% of the total number of fibres and 47% of the coated fibres were longer than lQjum. Based on the x-ray spectra, 64% of the fibres were identified as crocidolite, 15% as anthophyllite and 4% as amosite. No chrysotile fibres were identified. Of the fibres 17% were difficult to identify. The results for each case are shown in tables 5 and 6. DISCUSSION Occupational exposure and asbestos lunfi burden. 385 The present investigation shows that high occupational asbestos exposure is associated with high fibre concentration in lung tissue. It is not, however, possible to distinguish cases without occupational exposure from cases with low occupational exposure. This may be due to that it is difficult to evaluate the exact asbestos exposure in certain occupations. The find- ings are in consistence with other investigations (2). Asbestos lung burden and health effects. The concentration of fibres in lung tissue depends on both the intensity and the duration of the exposure. Further- more, a minimum lapsed time from the first asbestos exposure, i.e. the recidence time, is probably necessary for certain health effects to occur. Epidemiological studies (8) have shown that long observation periods of 30 to 40 years are necessary to study the health effects of asbestos exposure. In the present investigation all cases, even with high exposure, have a long and rather constant lapsed period from the onset of exposure. Ashcroft and Heppleston (l) found a long recidence time for asbestos fibres in cases of mesothelioma .unrelated to the fibre concentration and the grade of asbestosis. Furthermore, Ashcroft and Heppleston (1,4), found a significant correlation between fibre concentration in lung tissue and the grade of lung fibrosis in cases with slight and moderate asbestosis. However, no relationship between fibre concentra- tion and the pathological changes of severe asbestosis were found. They therefore suggested that the changes of severe asbestosis are due to the intervention of secondary pathological 386 processes as non-specific pulmonary infections. Whitwell et al (10) found that the fibre concentration in the lungs in cases of mesothelioma was closely related to the occupational exposure. Heppleston (5) suggests that the development of mesothelioma appears to be unrelated to the concentration of coated and uncoated fibres in lung tissue, but Bignon et al (2) found parti- cularly high fibre concentrations in cases of mesothelioma associated with asbestosis. The present investigation has shown that most fibres in lung tissue found by scanning electron microscopy are uncoated, shorter than fym and thinner than l^um. The results are in agreement with other investigations (1,2,4). Furthermore, only amphi- bole asbestos is identified in the lung tissue, which might be due to chrysotile asbestos changing properties in the lung tissue (5,6). In our investigation we found the highest fibre concentration in two cases of mesothelioma. In one of these cases, without any sign of lung fibrosis (case No.2), we found that 12% of the total fibres and 47% of the coated fibres were longer than 10/um. This is particularly interesting because experimental studies by Stanton et al (9), have shown that fibre carcinogenicity probably depends on fibre length and fibre durability. They found that fibres thinner than l,5un and longer than 8/um yielded the highest probability of pleural sarcomas. Due to the limited size of the lung samples in this investigation, we have not been able to study the distribution of fibres in different parts of the lung. 387 Our results must therefore be regarded as approximate concentrations. Furthermore, the material is small, and therefore it has been impossible to study the relationship between asbestos burden and different asbestos-related diseases. Further studies on the quantity and the size distri- bution of the fibres in lung tissue are necessary to evaluate the relation between asbestos lung burden and health effects. 388 TABLE 1 OCCUPATIONAL EXPOSURE GROUP I II III HIGH EXPOSURE LOW .EXPOSURE UNKNOWN EXPOSURE NUMBER OF CASES 7 3 ONSET OF EXPOSURE 1928 - 1 9 W 1935 - 1950 AGE AT ONSET 26 (15-33) ill (33-53) DURATION 19 (2 -35) 11 ( 2-28) AGE AT DEATH 66 (58-75) 66 (51-78) LAPSED PERIOD FROM ONSET 37 28 (21-38) (32-13) ARITHMETIC MEAN AND RANGE 389 13 55 (11-78) TABLE 2 FIBRE CONCENTRATION AND IDENTIFICATION (FIBRES/G DRY TISSUE) GROUP I HIGH EXPOSURE NUMBER OF CASES FIBRE CONCENTRATION 10 6 FIBRES PER GRAM OF DRY TISSUE FIBRES WITH POSITIVE ASBESTOS IDENTIFICATION % OF TOTAL NUMBER II LOW EXPOSURE 7 18,0 (2,2 - 36,0) 79 % 3 13 1,0 0,7 (0,3 - 2,4) 60 % (27 - 92) (27 - 86) ARITHMETIC MEAN AND RANGE x) 6 CASES 39o III UNKNOWN EXPOSURE (0,3 - 1,5) 2 32 (8 - ¥0 TABLE 3 PROPORTION OF COATED FIBRES SIZE DISTRIBUTION GROUP I HIGH EXPOSURE NUMBER OF CASES 9,6 % COATED FIBRES % OF TOTAL NUMBER FIBRELENGTH 7 < 5m % OF TOTAL NUMBER FIBRE DI AMETER <lm Z OF TOTAL NUMBER II LOW EXPOSURE 3 19,3 % X ) III UNKNOWN EXPOSURE 13 8,7 % (6,8 - 17,6) 59.2 17 I (38 - 71) 96.% ( 92-100) ARITHMETIC MEAN AND RANGE 3 CASES 391 45 % x x ) (37 - 55) 89 % 91 % (89 - 94) TABLE 4 FIBRE CONCENTRATION AND CAUSES OF DEATH FIBRE CONCENTRATION 10 6 PER GRAM OF DRY TISSUE PLEURAL FIBROSIS LUNG FIBROSIS 1 36,0 + + 2 32,8 + , 3 28,0 + + 4 9,4 + + 6 9,3 7 2,2 + ? 5 8,7 + + UNCLASSIFIED LUNG CANCER 8 2,1 EMPHYSEMA 9 0,3 10 0,3 CAUSE OF DEATH CASE NO, MESOTHELIOMA ASBESTOS IS BRONCHIAL CANCER ' APOPLEXIA CEREBRI 392 ? TABLE 5 INDIVIDUAL RESULTS. GROUP ONSET OF EXPOSURE AGE AT ONSET DURATION ^VGE AT DEATH ^APSED PERIOD FROM ONSET FIBRE CONCENTRATION 10 6 FIBRES PER GRAM DRY TISSUE FIBRES WITH POSITIVE ASBESTOS IDENTIFICATION % OF TOTAL NUMBER COATED FIBRES % OF TOTAL NUMBER FIBRE LENGTH<5 pm % OF TOTAL NUMBER £JBRE DIAMETER<1 ym S*OF TOTAL NUMBER I i-i CASE NUMBER GROUP I AND II 2 1944 1939 3 II 4 5 6 7 8 1928 1935 1941 1934 1938 9 10 1949 1935 1950 43 25 75 19 17 58 15 2 58 27 35 66 31 3 67 29 16 71 30 35 66 33 4 54 38 28 66 53 2 78 32 39 43 40 36 37 36 21 38 25 36,0 32,8 28,0 9,4 8,7 . 9,3 . 2,2 2,4 0,3 0,3 27 27 86 68 _ 7,5 17,6 19,3 _ _ 90 92 92 75 90 84 6,8 7,1 11,0 7,3 50 66 65 71 70 38 54 47 _ _ 100 95 99 100 99 92 90 89 - - + + + + + + + + CAUSES OF DEATH MESOTHELIOMA ASBESTOSIS BRONCHIAL CANCER + OTHER CANCERS CHR. BRONCHITIS WITH EMPHYSEMA PLEURAL FIBROSIS LUNG FIBROSIS + + + + + 393 + + + + TABLE 6 INDIVIDUAL RESULTS. CASE NUMBER 11 12 13 14 GROUP III 15 ! 16 17 18 19 20 ! 21 22 23 68 40 i 76 AGE AT DEATH 78 76 31 60 11 74 63 j 36 i1 FIBRE CONCENTRATION 1 0 6 FIBRES PER GRAM OF DRY TISSUE 0,6 0,3 0,6 1,3 0,7 1,5 0,4 0,4 1,0 0,7 ;o,8 0,5 0,8 * FIBRES WITH POSITIVE ASBESTOS IDENTIFICATION % OF TOTAL NUMBER 44 33 8 17 20 13 - - COATED FIBRES % OF TOTAL NUMBER FIBRE LENGTH<5 um % OF TOTAL NUMBER FIBRE DIAMETER<1 pm % OF TOTAL NUMBER j i 8,7 i 43 37 55 ; 94~' OCCUPATIONS CORK WORKER + + WELDER + INDUSTRIAL WORKERS + + \ + + + + "TAXIDRIVER + HOUSEWIFE + SCHOOLGIRL + OTHER OCCUPATIONS ... + CAUSES OF DEATH BRONCHIAL CANCER +. + + HEART DISEASE + + + + ACCIDENTS OTHER CAUSES + + OTHER CANCERS + + 1 + • 1- 39* + REFERENCES: 1. Ashcroft, T. and Heppleston A.G.: The optical and electron microscopic determination of pulmonary asbestos fibre concentration and its relation to the human pathological reaction. J. Clin. Path. 26 (1973) 224-234. 2. Blgnon, J., Sebastien, P., Fondimare, A, Bonnaud, G., Gaudichet, A., Janson, X. et Monchaux, G.: Etude quantitative et qualitative des fibres d'amiante dans l'appareil respiratoire humain. Contribution a l'évaluation du risque cancérigène pour la population generale. Rapport de Institut de Recherche Universitaire sur l'Environnement, Paris 1978. 3. Gylseth, B., Ophus, E.M. And Mowé, G.: Determination of fibres in human lung tissue by scanning electron microscopy. Submitted for publication in Scand. J. of Work Environ » Health. 4. Heppleston, A.G.: Correlation between the tissue response and asbestos fibre content. Environ. Health Perspect. 9 (1974) 147-148. 5. Jaurand, M.C., Bignon, J., Sebastien, P. and Goni, J.: Leaching of chrysotile asbestos in human lungs. Environ. Research , 14 (1977) 245-254. 6. Pooley, F.D.: Electron microscope characteristics of inhaled chrysotile asbestos fibre. Brit. J.of Ind. Med. 29 (1972) 146-153. 7. Pooley, F.D.: The identification of asbestos dust with an electron microscopi microprobe analyser. Ann. Occup. Hyg. 18 (1975) 181-186. 8. Selikoff, I.J., Hammond, E.C. and Seidman, H.: Cancer risk of insulation workers in the United States. In P. Bogovski, V.Timbrell, J.C.Gilson and J.C.Wagner (eds). Biological effects of asbestos. Proceedings of a Working Conference held at the International Agency for Research on Cancer, 2-6 October 1972. Lyon,France, 1973. pp 209-216. 395 ? Stanton, M.F., Layard, M., Tegeris, A., Miller, M. and Kent, E.: Carcinogenicity of Fibrous Glass: Pleural Response in the Rat in Relation to Fiber Dimension. J. Natl. Cancer Inst. 58 (1977) 587-603. Whitwell, F., Scott, J. and Grimshaw, M.: Relationship between occupations and asbestos-fibre content of lungs in patients with pleural mesothelioma, lung cancer and other diseases. Thorax, 32 (1977) 377-386. 396 SILICA DUST-ASSOCIATED PULMONARY LESIONS IN GRANITE WORKERS LACKING RADIOLOGIC EVIDENCE OF DISEASE N. Vi Vallyathan, and John E. Craighead Department of Pathology, University of Vermont College of Medicine, Burlington, VT, USA INTRODUCTION Inhalation of particles containing silica results in silicosis after prolonged periods of exposure. The disease is characterized anatomically by diffuse fibrosis and the presence of discrete fibrotic nodular lesions located in proximity to the respiratory bronchioles, arterioles, septae and pleura. These nodules contain loosely arranged, hyalinized collagen in the center and reticulin fibers in the periphery. In Vermont's granite industry, the widespread occurrence of silicosis and an increased susceptibility to tuberculosis were the scourge of workers during the early decades of this century. Sub- sequent to the institution of dust controls in 1937, a substantial decrease in the prevalence of silicosis was documented in annual chest roentgenogram surveys (Hosey et al., 1957). This was attributed to the lowering of environmental dust concentrations to 10 million particles per cubic feet (mppcf) from an average of 60 mppcf before enforcement of controls (Hosey et al., 1957). At present environmental dust concentrations, it has been shows that prolonged exposure is necessary to induce changes in chest radiograms and ventilatory function (Hosey et al., 1957| Theriault et al., 1974b,c). Since clinical expression of the disease occurs only after an elapsed period of years, it is not known whether subtle degrees of pulmonary fibrosis occur 397 in workers lacking radiological abnormalities and clinical symptoms. This investigation was undertaken to determine the extent and severity of subclinical disease and its progression in the lungs of workers employed in the Vermont granite industry since the institution of controls in 1937. It was designed to determine whether or not current radiological and physiological techniques are adequate to detect and monitor the development and progression of cryptic disease. MATERIALS AND METHODS Samples of lung tissue from 15 workers who had been employed in the Vermont granite industry since 1937 were studied. Fourteen of these specimens were obtained at autopsy and one by lung biopsy. Occupational records were reviewed to confirm that none of the cases had been employed in a dusty trade before 1937 and to determine the duration and type of industrial exposure. For pur- poses of comparison, studies also were carried out on autopsy tissue from four subjects who had been employed as granite workers for varying periods of time both before and after 1937. The Vermont Department of Occupational Health maintains health and industrial dust exposure records on wotrkers employed in the state's dusty trades. Annual chest radiograms are available on most of these workers, and the results of pulmonary function studies and smoking histories are known on many. The most recent available chest radiogram on each of the cases was examined by a member (B reader) of the panel of the UICC Committee who had no knowledge of the origin of the x-ray. Lifetime dust exposures and dust years were calculated according to the method of Theriault et al. (1974a). Table I summarizes the available health and in- dustrial exposure information and the primary cause of death. 398 Lung samples, either in paraffin blocks or formalin, were processed for light microscopy, and 10 serial sections of 7 nm thickness were prepared. The first and tenth sections were stained with hematoxylin and eosin and studied by light and polarized light microscopy. Adjacent serial sections 2 through 9 were used in scanning electron microscopic (SEM) studies employing secondary and backscattered imaging and mapping techniques. Sections were placed on carbon planchets, deparaffinized, carbon coated and examined by SEM. Elemental analyses were made according to the method of Brody et al. (1978). Integrated x-ray counts for Mg, Al, Si and Fe were made for 100 seconds and corrected for background by the subtraction of calculated bremsstrahlung derived by the channel averaging technique (Brody et al., 1978). For these studies a JEOL JSM-35 SEM with a Kevex 5100 series x-ray spectrometer were used. Quantitative x-ray fluorometric analysis on lyophllized lung tissue and x-ray crystallographic studies on tissue digestates were made in those cases where tissue was available. Particle analyses on tissue digestates also were made when tissue was available. RESULTS Table I summarizes exposure data and the results of clinical and pathological findings on the 15 patients in this series. As can be seen, radiological abnormalities suggestive of either pulmonary fibrosis or silicosis were not evident in the lungs, and pulmonary insufficiency was not prominent in functional tests. Although 5 of the 15 had bronchogenic carcinomas, the series is highly selective, and no conclusions regarding the possible car- 399 cinogenlc effect of silica exposure can be made. Analysis of silicon in selected, localized fibrotic areas of the lung by x-ray spectrometry demonstrated substantial concentrations of this element (Fig. 1). Interestingly enough, the silicon in the tissues of individuals with long periods of exposure (Table II) and overt silicosis was not substantially greater than amounts found in the pulmonary tissue of the cases comprising this series (Fig. 1 ) . The lungs of each of the 15 patients exhibited varying degrees of focal fibrosis (Figs. 2,3) and, in one case, localized nodular lesions typical of silica dust exposure (Figs. 4,5). In none of the patients was the fibrosis severe or confluent. Crystalline particulate matter was rarely found in these lesions by polarized light microscopy, although it was readily demonstrable by backscattered scanning electron microscopy (Figs. 6-9). XES analysis and x-ray mapping techniques were employed to further characterize dust particles in these lesions and in tissue digestates (Figs. 10, 11). These techniques proved essential in relating lesions to silica dust deposition. DISCUSSION The prevalence of silicosis and silico-tuberculosis among Vermont granite workers prompted a series of epidemiological investigations that resulted in the institution of dust control measures in 1937 (Russell et al., 1929¡ Russell, 1941¡ Urban, 1939). Russell et al., (1929) demonstrated a correlation between exposure levels in different workplaces and the incidence of silicosis. These studies led to the conclusion that a safe dust level in the granite industrv would be 9 to 20 mppcf. 4oo After the institution of the present threshold limit value of 10 mppcf In 1937, there was a considerable decrease in the prevalence of silicosis, from a high of 43% before 1937, to a low of 16% as monitored by chest radiograms (Hosey et al., 1957). Further evaluations of workers employed in the industry for periods of as long as 26 years since 1937 showed no silicosis by chest roentgenograms (Ashe and Bergstrom, 1964). However, recent studies on the pulmonary function of granite workers have shown a decrease of 2 ml/dust year after corrections were made for ancillary contributing factors (Theriault et al., 1974b,e). Nevertheless, an average of 32.5 dust years was found necessary to affect the ventilatory function of 50% of workers and an average of 46 years of dust exposure was associated with abnormalities in 50% of the x-rays (Theriault et al., 1974b,c). It is evident from these studies that the effects of dust on pulmonary function seem to appear before radiological changes. Clearly, the clinical expression of disease as reflected either in pulmonary ventilatory function or radiological abnormalities is delayed due to the extended latency period of the disease. Histopathological study of the lungs of our cases, with exposure histories ranging from 5 to 30 years, documented the presence of subclinical disease. Analyses by XES suggest a rough correlation between the severity of fibrosis and the concentration of silicon. However, it was of interest to note that the amounts of silicon in individual lesions often approximated the quantities demonstrated in the lesions of lungs exhibiting classical silicosis. This observation supports the view that silicosis is a progressive process resulting in the deposition of increasing amounts of fibrous tissue with the passage of time. Thus, a reduction in dust exposure may only reduce the number and distribution of discrete lesions which 4o1 ultimately develop in the lung. Although histopathological studies showed extensive pulmonary fibrosis, polarized light microscopical studies usually failed to detect dust particles in fibrotic lesions. However, when the same lesions were studied by scanning and backscattered electron microscopy with x-ray microanalysis and x-ray mapping techniques, it was possible to document the presence of crystalline silica. These modern approaches make possible cause and effect associations that otherwise would not be possible. ACKNOWLEDGMENTS This work was supported by U.S. Public Health Service grant #PHS 17292-04/3 to the Vermont Lung Center. The contributions of Drs. Jane Brisbane, Leonard Bristol, Arnold Brody, Roy Buttles, Robert Christie, Peter Dietrich, Larry Fine and John Froines are gratefully acknowledged. Ms. Phyllis Alexander, Ms. Lena Bizzozero, Ms. Judy Kessler, Ms. Marilyn White and Mr. Loren Hahn provided excellent technical assistance. 4o2 REFERENCES Ashe, H.B. and Bergstrom, D.E.: Twenty-six years' experience with dust control in the Vermont granite industry. Industr. Med. Surg. 33:73-78, 1964. Brody, A.R., Vallyathan, N.V. and Craighead, J.E.: Use of scanning electron microscopy and x-ray energy spectrometry to determine the elemental content of inclusions in human tissue lesions. In : Scanning Electron Microscopy, Vol. II, SEM, Inc. (Johari, 0, ed.), Chicago, 1978, pp. 615-622. Hosey, A.D., Trasko, V.M. and Ashe, H.B.: Control of silicosis in Vermont granite industry. U.S. DHEW Pub. No. 557, 1957. Russell, A.E.: The health of workers in dusty trades. VII. Restudy of a group of granite workers. U.S. Govt. Printing Office, Public Health Bulletin #269, Washington, 1941, p. 71. Russell, A.E., Britten, R.H., Thompson, L.R. and Bloomfield, J.J.: The health of workers in dusty trades. II. Exposures to siliceous dust (Granite Industry). U.S. Govt. Printing Off., Public Health Bulletin 187, Washington, 1929. Theriault, G.P., Burgess, W.A., DiBerardinis, L.J. and Peters, J.M.: Dust exposure in the Vermont granite sheds. Arch. Environ. Health 28:12-17, 1974a. Theriault, G.P., Peters, J.M. and Fine, L.J.: Pulmonary function in granite shed workers of Vermont. Arch. Environ. Health 28:18-22, 1974b. Theriault, G.P., Peters, J.M. and Johnson, W.M. : Pulmonary function and roentgenographic changes in granite dust exposure. Arch. Environ. Health 28:23-27, 1974c. Urban, E.C.J.: Ventilation in the granite industry. J. Ind. Hyg. Toxicol. 21:57-65, 1939. 4o3 i «s CD £ a bev •H 0 G ci 3-H a <H CD O fc. a><H O-H i o a a 3 as •-I u s^ n« i * oo m t» t» ««tie m to i i i m CO m CM n t» o c» *•« i H a « h 0) tù > n co t» nei to ss a-a a a Ü» co en i v r-i +> u OJ it s« ne 00 i-I in to i tí O a 4 O •o I IV i i FVC FEV,. a i i >w 00 m (O o to CM 10 Ci CM CM I ti « f- I m H CO S ' 1-1 h x¡ a •o e O ed Cd r H OTO. i* f-* <D (D 0) £*£§ e4 9 > CO J O I CM U I O • co O TÍ O cd o. co co m CD • < o uss 4o4 'S" CM I CM I §«§• ss I us < W a o w co P CO 01 -H S P O -H in -a 3 u O al M U co -H A h 3 « al a a» < co E- • < CO «S E-a CM Of co • co E-OS co < — . co CM O) O P W ta >. ss I E M p E-iCO 3 W O O M R hfl J M 3 CM CO CD CO CO w CM CO CM CO I o co to iH CM CM I t~ t - CO COO) O) rH iH I 1 1 CO 0> t» CO CO 0) 0) iH iH I -P 1 « M 0, 0> CO h O O 04 a a, CO CTI CO § M CO E H BS << gp o o •p » 3 eS oco O < CO co I o I (BO Il 0) V •P 3 O CM I I b B » -H CD M O W -P ta 0 P. » i co •tì «i UH Cil A co o CO W CO • < O O ¡S 4o5 ABSTRACT In Vermont's granite industry, the widespread occurrence of silicosis and increased susceptibility to tuberculosis was the scourge of workers prior to 1937. Subsequent to the institution of dust controls in 1937, a significant decrease in the incidence of silicosis was documented by annual chest radiograms• Since clinical expression of the disease occurs only after prolonged exposures to dust, it is not known whether subtle degrees of pulmonary fibrosis are occurring in workers lacking radiological abnormalities and clinical symptoms. This investigation was under- taken to determine the extent and severity of fibrosis and concentrations of dust in the lungs of workers employed after 1937 and to ascertain whether current radiological, physiological and histopathological techniques are adequate to diagnose and monitor the development of cryptic disease. Fifteen workers employed since 1937 and four who had worked in the granite industry before 1937 were studied using light and polarized light microscopy, scanning and backscattered electron microscopy, x-ray energy and x-ray fluorescent spectrometry and xray crystallography. Chest radiograms and pulmonary function tests conducted on these subjects over a period of years prior to their deaths were evaluated and dust exposure data was assessed.. These correlative studies indicate that subtle dust-related fibrotlc lesions are present in the lungs of granite workers who exhibited no specific radiologic abnormalities and limited pulmonary function disability premortem. These findings suggest that the dust ex- posure limits currently employed in the industry must be questioned. 4o6 Pruebas hlstopatolÓRlcas de la prevalencta de silicosis asintomática entre los trabajadores del granito. N. V. Vallyathan y J. E. Craighead (Estados Unidos) En la industria del granito del Estado de Vermont, hasta 1937 amenazaba a los trabajadores una silicosis generalizada y una gran susceptibilidad a la tuberculosis. Gracias a la creación de controles de polvo en ese año, las radiografías toráxlcas anuales revelaron un importante descenso en la incidencia de la silicosis. Como la expresión clínica de la enfermedad sólo surge al cabo de una prolongada exposición al polvo, no se sabe si entre los trabajadores que no presentan anormalidades radiológicas o síntomas clínicos no se está produciendo en grado sutil una fibrosis pulmonar. Esta investigación fue emprendida para determinar la extensión y la gravedad de la fibrosis y las concentraciones despolvo en los pulmones de los trabajadores empleados después de 1937, para verificar si las técnicas tradicionales radiológicas, fisiológicas e hlstopatológlcas son adecuadas para diagnosticar y controlar el desarrollo de una enfermedad críptica. Se examinaron 15 trabajadores que habían trabajado desde 1937 y cuatro que habían trabajado en la Industria del granito antes de esa fecha, utilizando la microscopía óptica con luz polarizada, la microscopía electrónica por centelleo y retroreflejo, la energía con rayos X, la espectrometría fluorescente con rayos X y la cristalografía con rayos X. Se compararon las radiografías toráxlcas, la función pulmonar y la exposición al polvo con la gravedad de la fibrosis y las concentraciones de polvo. Se obtuvieron pruebas hlstopatológlcas y cuantitativas de la presencia de silicosis asintomática. 4o7 THE ROLE OF PULMONARY TUBERCULOSIS IN THE CAUSATION OF PROGRESSIVE MASSIVE FIBROSIS IN COAL WORKERS IN GREAT BRITAIN J. A. Dick, United Kingdom The National Coal Board of Great Britain set up Its Periodic X-ray Service In 1958 with two principal objectives. These were firstly to offer the Individual miner a chest xray at his working place and by achieving a high response rate to establish the real national prevalence of Coal Workers' Pneumoconiosis, the most Important occupational hazard In the Industry, and secondly to use serial x-rays as a monitor of the effectiveness of dust suppression. Mobile x-ray units taking full-size films visited every colliery In all coal fields and employing suitable propaganda endeavoured to x-ray as many men as possible. Five years were required to complete the first round of surveys. The scheme was entirely voluntary, but over 85 percent of men attended (current response Is 92 percent). The films were classified for Coal Workers' Pneumoconiosis using the ILO (1958) Classification of Radiographs of Pneumoconioses, and it was thus possible to obtain the national and regional prevalences of this condition In the British Coal Mining Industry. It soon became clear, as Table 1 shows, that there was a wide range In the prevalence of pneumoconiosis In the various coal fields, and Table 2 Indicates that since 1959-63, although there has been a significant decline in overall prevalence, regional variations remain virtually unaltered. 4o9 TABLE li Prevalence of Pneumoconiosis in the Coalfialds of Great Britain 1959 - 1963 AREA HEN X-RAYED CAI 1 CAT 2 CAT 3 •iCTAL SIMPLE PNEUMOCONIOSIS PMP TOTAL Soottisb 53,849 3.0 w 0.3 .5.4 0.3 5-7 North East 94,624 9*1. 2.5 O.4 11.9 0.8 I2.7 North Yorkshire 23,214 7.5 4.2 O.4 12.1 0.6 I2.7 Donoaster 23,092 8.0 3.9 0.5 I2.4 0.8 13.2 Barnsley 27,776 6.2 3.8 0.4 IO.4 1.0 II.4 South Yorkshire 26,91S 7.4 4.2 0.3 12.0 0.7 I2.7 North Derbyshire 23,143 3.4 2.1 0.4 3.9 0.3 6.2 North Nottinghamshire 24,075 3.4 2.2 0.4 6.0 0.5 6.5 South Nottinghamshire 21,760 3.1 1.9 0.2 5.1 0.2 5.3 South Midlands 18,421 2.7 1.3 0.1 4.0 0.2 4-2 Western 61,966 5.6 4.0 1.2 10.8 1.2 12.0 South Wales 60,286 14.O 5-9 I.7 2I.7 3.6 25.3 3,875 7.6 4-3 1.4 13.4 2.1 15.5 462,999 7.0 3.3 1 0.7 11.0 1.1 Kent GREAT BRITAIN 12.1 1 4-1 o TABLE 2: Pra/tilcnce of Pneumoconiosis in tho Coalfields of Great Britain 1974/75 AREA Scottish . 1 TOTAL ¡ PMP SIMPLE PNEUMOCONIOSIS ; CAT 1 CAT 2 2.1 0.2 0.0 1 2.4 i 0.1 2-5 i 1 7.9 ¡ 0.3 8.2 CAT 3 TOTAL PREVALENCE North East 6.5 1.3 0.1 Forth Yorkshire 5.4 2.2. 0.1 7, | 0.5 8.2 Donoaster 5.1 2.2 0.0 7.3 ¡ O.4 7.8 Barnsley 4.7 1.6 0.2 6.4 0.6 7.0 South Yorkshire 4.4 1.5 0.1 6.0 0.3 6.3 North Derbyshire 4.8 1.1 0.0 5.9 0.2 6.1 North Not t inghamshire 4.1 1.2 0.1 5-4 0.6 6.0 South Not tineham3hire 4.0 0.7 0.0 4.7 0.2 4.9 South Midlands 2.6 0.3 0.1 3.0 0.2 3.2 Western 5.1 2.0 0.3 7.4 0.6 8.0 13.9 3.9 0.3 ! 18.0 3.2 21.2 Kent 5.2 1.4 0.1 6.8 0.5 7.3 GREAT BRITAIN 5.9 1.7 0.1 7.7 0.7 8.4 South Wales . 411 In planning the Perlodix X-ray Scheme It was recognised that adequate records of surveys and of individual miners must be maintained! and from the outset as much detail as possible has been stored in computer tape at Centre. the National Coal Board Computer Information for each miner who had a chest x-ray included agef place of work, pneumoconiosis (recorded in category of the ILO Classification) and the presence of other pathology. As the individual miner had successive chest x-rays so the national computer file was updated to include the latest information. It was thus possible to publish a yearly national prevalence (i.e. for one fifth of the total population) and a quinquennial prevalence for the entire industry. As the programme developed it became evident that the Periodic x-ray Service was accumulating a mass of data unlikely to be available to other organisations involved in the problem of Coal Workers' Pneumoconiosis, and for this reason it appeared to be highly desirable to make use of periodic x-ray data in an effort to make some contribution to the understanding of Coal Workers' Pneumoconiosis. It is generally agreed that, inter alia, there are two principal problems in the field of pneumoconiosis for which, as yet, no satisfactory explanation has been given. The first is What determines individual susceptibility to dust? The second - What causes the change from simple to complicated pneumoconiosis in the individual miner? It seems probable that from the data available some contribution could be made to the problem of complicated pneumoconiosis. So far as is known a long-term follow-up of Progressive Massive Fibrosis has not been made. 412 It was therefore, decided that an attempt should be made to Identify all new attacks of Progressive Massive Fibrosis developing in the second survey period. An attack of Progressive Massive Fibrosis would be defined as the occurrence of categorisable complicated pneumoconiosis in an individual attending for x-ray in the second round of surveys (1964-68) who had also attended during the first round of surveys (1959-63) and whose film then did not show complicated pneumoconiosis. Having identified such individuals! an effort would be made to establish, as far as possible, the natural history of each man up to the date of the investigations (1975-76), approximately ten years later. Method In order to ensure as accurate a diagnosis as possible it was decided to use data from epidemiological readings as this ensured that two opinions were available for each pair of films. Since the inception of the Periodic X-ray Scheme the coalmining population has changed drastically and, in theory, changes in prevalence could be explained by the selective departure (or retention if prevalence was static or increasing) of men with pneumoconiosis. To overcome these difficulties of changing populations a special study is made of men who have remained at their own colliery throughout the interval between surveys. At each colliery a sub-population is selected for special study. These are men who were x-rayed on both the current and previous surveys, and who were employed on the coalface at the time of the earlier survey. Each man's pair of films is assembled in 413 ten batches i corresponding to twice the number of doctors engaged In film reading. Two batches are sent to each doctor who, after recording his assessments of pneumoconiosis on each pair of films passes each batch to a different check reader, who does the same. From these readings an Index summarising the changes In the x-ray films of the colliery sub-population Is obtained« This Index Is to be Interpreted only as a means of ranking the collieries In terms of x-ray changes which are considered to reflect Increased dust retention« All attacks of Progressive Massive Fibrosis agreed by two readers were automatically Included In the population to be studied« Although agreement between readers on the diagnosis of Progressive Massive Fibrosis Is generally very close, there Is Inevitable some difference of opinion at the level of the lower limit of Category A. Those cases showing some disagreement were reviewed by all the Board's readers and a majority consensus reading obtained« If the consensus was In favour of Progressive Massive Fibrosis the Individual concerned was Included In the study, If not he was excluded« The use of epidemiological data automatically reduced the numbeis of men available for study« However, of the sub-population of 112,000 who had chest x-rays between 1959 and 1963 and again five years later, 237 were selected on the basis noted above. 3 gives their distribution over the various coalfields In the United Kingdom together with the prevalence In each coalfield at that time. 414 Table TABLE 3i Distribution, by coalfield and age group, of men selected to be followed up, and prevalence at the time of the PMF attack. AGE CROUP (ACE AT DECEMBER 1976) COALFIELD UNDER 35 to 35 44 - - - 1 - 2 3.2 North East 1 7 18 32 62 13.0 Yorkshire - 1 23 i 36 65 10.9 Scottish 45 to 54 65 to 74 55 to 64 75 and above TOTAL TOTAL PREVALENCE 1964-1963 i Western - 1 2 Î 18 24 9-7 East Midlands - 2 5 i 11 19 5-3 South Wal«s - 13 20 25 59 23.5 - - 3 3 - 6 U.9 1 24 72 15 237 10.7 - Kent CHEAT BRITAIN 1 125 The precise stimulus for the change from simple to complicates pneumoconiosis is not understood and It may be that there Is no single stimulus common to all cases. Nevertheless, It Is general- ly accepted that the principal factor probably lies in one of the following - pulmonary tuberculosis, silica, total dust exposure, immunological reaction and finally other respiratory trauma such as lung infection. This paper reports the findings on the place of pulmonary tuberculosis in the population studied. The first step in the investigation was to establish whether or not an Individual was still alive and if so his current address. It will be seen that of the 237 subjects in the sample 184 were 415 still alive, but many had moved to parts of the country Inaccessible to the Medical Service. Of the remainder still living without coalfield areas it was possible to personally interview 97 and to contact by postal questionnaire a further 43. Twenty-four men were traced but could not be personally contacted and 20 could not be traced. Fifty-three men had died and details of death certificates were available for 51. Thus of the total sample there were 21 men for whom no information of any kind, other than their initial radiological appearance, was available. Analysis of these men did not indicate any significant bias and they were therefore excluded from the investigation, thus leaving a total of 216. In addition to the clinical details available from completed questionnaires, further information was obtained by scrutiny of hospital and Pneumoconiosis Medical Panel records, which were readily made available. For this reason all results are expressed as a percentage of the total sample (216). Initial scrutiny of the data available indicated as Table 4 shows that there were 11 cases of positive sputum from 172 examined. In addition there were 3 individuals who appeared to have some suggestion of pulmonary tuberculosis although sputum was negative. Therefore, there appeared to be 14 cases to be followed up clinically. Despite considerable efforts it was not possible to obtain any more information in one cases. Detailed examination of the clinical records showed that of the 13 remaining 8 were sputum positive, a further 2 were diagnosed firmly as tuberculosis on clinical and radiological grounds and were treated by chemotherapy. There were, therefore, 10 cases in all which could be regarded as definitely 416 tuberculosis giving 4.2 percent of the total numbers followed up. All 10 cases were treated with anti-tubérculous drugs. In no case did this have any beneficial effect on the extent of the PMF lesions i on the contrary, in at least one case tuberculous cavitation took place while the patient was on therapy. The average age of those who were known to be still alive was 63.5 years. Two men with positive tuberculosis who were known to have died had an average age of 64 years. TABLE 4i Sputum « Examined directly and culture COALFIELD POSITIVE CULTURE DIRECT NEGATIVE NOT EXAMINE]) TOTAL Scottish - - - 2 2 North East - 1 12 13 25 Yorkshire 1 2 24 39 64 - 7 3 Western • - 15* East Midlands 1 1 14 1 16 South Wales - 3 24 21 45 Kent 1 •H 4 - 5 85 79 172* _ GREAT BRITAIN * Including 5 examinations without results 417 TABLE 5i Distribution of the cases of active tuberculosis and distribution of categories of pneumoconiosis. — — — — — ' COALFIELD NO. CATEGORY C? PKEOKOCOMZJSIS Scottish - - North East i-i IB q Yorkshire 2 2B q 2B q Testern 2 OA 3Í. q East Midlands 1 IC q South Wales 3 IC q Kent 1 2A q 1C x 1A q It is interesting to note that, with one exception, the small opacities were all "q" type and that there were no "p" type opacities present in any of the casest Numbers involved were so small as to make it unlikely that the absence of "p" type opacities is of any significance. In only one case had the Rheumatoid Arthritis Screening Test (RAST.) been carried out and was negative. In only one case were the radiographic appearances considered to resemble Caplan type change. In summary, of 237 attacks of complicated pneumoconiosis, 10 were proved to have preceding or concommitant pulmonary tuberculosis. If clinical improvement resulted from anti- mi 8 tuberculous therapy could be accepted as adequate evidence that the lung lesion was In fact due to tuberculosis then this figure could be Increased to 12 giving a percentage of 5.06. Deaths It is routine practice in the United Kingdom when a miner dies and has, or is thought to have, pneumoconiosis that his death is reported to the District Coroner. Invariably a post-mortem is carried out and on /'the basis of the pathologist's report the coroner decides the cause of death. lungs In addition it is customary for the of any deceased miner to be forwarded to the nearest Pneumo- coniosis Medical Panel office where they are examined by Panel pathologists. It is the responsibility of the Panel to decide what part, if any, pneumoconiosis played in the cause of death, and this decision influences the payment of compensation to dependants. From these two sources of information it is possible to obtain accurate information on the causes of death and to decide what contribution, if any, pneumoconiosis made to death. Table 6 gives the primary cause of death for 54 men on whom post mortems have been carried out, and it will be seen that in no case was tuberculosis considered to be a primary cause of death as stated in the death certificate. As it is possible that the real cause of death may not be the primary cause of death, the death certificates were re-examined and the results of the re-examinâtion (see Table 7) once again shows that in no single case was tuberculosis considered to be a factor either primary or principal. 419 TABLE 61 Deaths - Various pathologies CWP CARDIO VENTRICULAR CIÎ2ST ' VASCULAR HÏPERTROFHÏ INFECTION COALFIELD Scottiah 1 " _ North East .- ' 1 ÇA : PTB OTHERS ' NO LUHG 1 RECORD 1 - - - - - 3 5 4 2 - 2 . 1 Yorkshire - 4 1 2 1 - 5 j? Eestern 1 3 1 2 - - 2 - East Midlands 2 - - - 2 - - - louth Wales 2 - - 1 - 3 - Kent 1 . 2 - - - - - - CREAT BRITAIN . 15 7 8 6 - 12 :1 ! TABLE 7,: Deaths - Pathology on Re-Examination COALFIELD cup ! CARDIO 1VASCULAR | VENTRICULAR HYPERTROPHY cnnsT CA INFECTION LUNG PTB 1 - - - - North East 8 3 W 1 2 - Yorkshire f-i 5 - 1 1 Testern 3 3 - 1 - East Midlands 2 - - - South Vales 1 2 - - Kent 1 - r-l - ! 16 I " 2 " 1 5 f. - 2 - 2 - - - 1 - 3 - " 12 14 42o NO RECORD Soottish GREAT BRITAIN OTHERS It would apprear from this Investigation that pulmonary tuberculosis Is not a principal factor In the causation of progressive massive fibrosis In British miners. It may well be, how- ever, that a ten-year follow-up Is not adequate. To Increase the period of follow-up would present formidable epidemiological problems because of the difficulty of tracing men and because of the significant number likely to have died. 421 Función de la tuberculosis pulmonar como causa de la fibrosis masiva progresiva en los mineros del carbon. J. A. Dick (Reino Unido) No cabe duda de que la etiología de la evolución de la fibrosis masiva progresiva sigue siendo uno de los interrogantes, importantes en la historia natural de la neumoconiosis. En diversas épocas se han intentado explicaciones diferentes y tal vez la más difundida ha sido que la tuberculosis pulmonar desempeña una importante función en la patogénesis de la fibrosis masiva. En el presente trabajo se exponen las constataciones del estudio a largo plazo de pacientes que han sufrido nuevos ataques de fibrosis masiva durante el período 19591963 a 1964-1968. Se describe el método utilizado para seleccionar los casos al mismo tiempo que los problemas que se presentaron para encontrar esas personas y obtener información de ellas. Se exponen las constataciones clínicas con especial referencia a la tuberculosis pulmonar. Se llega a la conclusión de que la tuberculosis pulmonar no desempeña una función preponderante como causa de la fibrosis masiva progresiva entre los mineros británicos. 422 THE HIGHER OXIDES OF NITROGENI A ROLE IN ALTERING PULMONARY RESPONSE TO INJURY? Tee L. Guldottl, Department of Environmental Health Science, The Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland, USA In considering the pathophysiology of occupational lung diseases, we customarily treat each exposure as a separate clinical entity. Yet we know that this Is an oversimplification! combined exposure Is probably the rule rather than the exception In occupational settings» With our rapidly developing state of knowledge, we now have sophisticated concepts and techniques which allow us to examine our previous simplifying assumptions. Among these assumptions has been the concept that an occupational lung disease, such a pneumoconiosis, consists of the specific tissue response to a particular Inhaled agent. We are now In a position to admit the possibility that the tissue reactions to Inhaled dusts In the pneumoconioses may be altered by simultaneous exposure to non-partlculate inhalants. If It Is true that non-partlculate Inhaled agents may modify the tissue response to particles, then an appropriate model for this phenomenon would be nitrogen dioxide. Nitrogen dioxide (N02) and the other higher oxides of nitrogen may coexist with airborne particulates In a number of occupational settings. In arc welding, N0 ? may accumulate to high concentrations In enclosed 2 3 spaces. In underground mining operations, N0 2 may be present as a consequence of explosive detonation ' or in much lower quantities from diesel exhausts. In agriculture occasional exposure 423 to NO? results in the well-recognized condition called silo fillers' disease, and may coexist in the same worker with inhalation of organic dusts. Most studies of particulate inhalation and toxic gas inhalation examine the effects of exposure to individual agents. This is the first necessary step in understanding the process of tissue injury and repair, but studies of individual exposure cannot adequately describe the common situation of sequential or simultaneous inhalation of more than one potentially toxic inhalant. The oxides of nitrogen, particularly NO,, are now among the best understood toxic gases, and a large body of work is available describing their effects on the lung. It seems appropriate to select NO, as a model to explore the question of whether the pulmonary response to injury, especially in the pneumoconioses, may be modified by a toxic gas. Few studies have examined the effects of mixed exposures to particulates and to NO,. Some of these have investigated the role of particles as vehicles for the deeper penetration of NO, into the lung. In the studies of Boren, respirable carbon particles saturated with adsorbed NO, were inhaled by mice. Compared to animals inhaling either NOj or carbon particles alone, combined exposure resulted in focal alveolar simplification associated with carbon deposits and a reduction in infiltration by macrophages. On the other hand, in the work of Furiosi, Crane and Freeman simultaneous exposure to only 2 ppm of NO,, and to aerosolized sodium chloride did not appear to produce a pattern different from NO, alone in mice.8 J 2 Another line of investigation has considered the possibility of interactive or additive effects of combined exposure to NO, 424 and particles which are fibrogenic. Studies by Daniel-Moussard and Lewis and their colleagues bear on this question.9' 10 Rats exposed to both NOy and either anthracite or quartz dust had a higher frequency of anthracotic and silicotic plaques after 5 q to 8 weeks compared to animals inhaling the dusts alone. After 3 months, the dry weight and the collagen content in lungs of rats exposed to both NCK and quartz dust were higher than in lungs exposed to either alone, but the combined effect appeared roughly q additive. Beagles chronically exposed to NO, and to ferric 3 11 oxide particles, a dust which is usually well tolerated, developed increased airway resistance compared to animals chronically exposed to NCK alonei this suggest an interaction. Gross et al, exposed guinea pigs intermittently to high doses of NC>2 at variable concentrations, about 44 ppm for most of the experiment. They followed this with intratracheal injection of quartz, coal, or blast furnace stack dust, the latter containing Fe2no, Situ, AljO-j, and carbon. They found a partially protective effect, with the highest mortality in the group exposed to quartz dust alonet there was no association between emphysematous changes attributed to NO^, and the distribution of pneumoconlotie plaques. 12 It is difficult to interpret the results of this study because of the unusual exposure pattern, the low incidence of emphysematous changes compared to other studies, the use of both guinea pigs and hamsters (the latter known to be relatively resistant to the effects of NO2 ), and the use of water rather than normal saline as the vehicle for intratracheal instillation of the dusts (hypotonicity 13 is known to disrupt macrophage activity ) . Nonetheless, this one study offers tentative evidence for inhibitory interactions be- 425 tween N0 2 and flbrogenic dusts. Lacking more definitive data on combined exposure, it may be useful to examine the basic pathophysiology of NO2 In order to identify processes by which the handling of dusts may be disturbed. In a set of experiments performed on dogs, we adapted a technique of unilateral bronchial intubation which had originally been developed in 1930 by Van Allen for studies on collateral ventilation. The technique involved intubating the anesthetized ani- mal with a stainless steel cannula and then passing the cannula into the left main bronchus (Figure 1). This bronchial cannula had an expandable head which sealed the bronchial lumen (Figure 2). The left lung could then be ventilated through the bronchial cannula and the right lung could be ventilated through the intratracheal cannula. This system has a number of practical advantages in studies of acute toxic inhalation. The clearance mechanisms of the upper airway are bypassed, permitting delivery of a constant, known concentration of gas to the lower respiratory tract. The contralateral lung may be ventilated with room air or oxygen, and serves both as a control and to support the animal through the experiment. Using this system, we exposed 5 anesthetized beagles to 37.2 ppm NC>2 delivered to the left lung for 4 hours. The opposite lung was ventilated with room air, containing no detectable N0 2 . We measured oxygen uptake by each lung at intervals and at the con- clusion of the exposure sacrificed the animals with an intravenous bolus of barbiturates and fixed the lungs by bronchial and intraarterial infusion of glutaraldehyde under physiological pressures. We then examined the parenchymal tissue of both lungs by transmission electron microscopy and compared them using the morphometric techniques developed by Weibel and colleagues.16 426 We found an early, reversible decline in oxygen uptake in the exposed (left) lung compared to the unexposed (right) lung, a difference best explained by induction of a ventilation-perfusion inequality. Morphologically and morphometrically, we found swell- ing and increased numbers of pinocytotic vesicles in the capillary endothelium of the exposed lung, associated with early interstitial edema, with little visible epithelial damage (Figures 3 and 4 ) . Morphometrically, the entire alveolar-capillary barrier was increased in volume and there was evidence for deformation of the shape of the interstitium (Figure 5 ) . Combining this new data with the results obtained by other workers, in particular Freeman, Evans, von Nieding, Kosmider, Ehrlich, and Sherwin and their colleagues, we proposed a schema for the pathophysiology of NCU toxic inhalation. rendering of this schema is giving in Figure 6. A simplified If this formulation is acceptably close to the truth, we may identify certain points at which NOj at concentrations in the range of tolerable acute occupational exposures may plausibly interfere with particle distribution and disposition, based on our present knowledge of the handl1 7-1 Q ing of inhaled dusts i 1) N 0 ? is a potent bronchospasm-inducing agent, so that inhalation leads to an acute increase in airway resistance and a reduction in i 20 airflow. ' This results in more turbulence and increasing nonuniformity of particle deposition, with a tendency for particles to sediment more centrally and less in peripheral airways. 2) N0 2 paralyzes ciliary activity in this concentration range and thus would interfere with mucociliary clearance. Some cilia may be destroyed by chronic exposure so that this interference might persist long after exposure ceased. 427 One would then expect reduced clearance of dust by this mechanism. 3) Alveolar macrophages appear to be particularly susceptible to the toxic effects of N02« experimental NCU exposure! Phagocytosis is markedly inhibited after Cell migration may also be impaired be- cause NO, could deprive the cell of energy for motility by interfering with electron transport mechanisms. 4) Alveolar macrophages injured by NOj may release locally pro- teolytic enzymes resulting in focal alveolar destruction. This effect, which is known to occur in other conditions of macrophage 21-23 and neutrophil toxicity and inflammation. might enhance the "spillage" or secretion of lysosomal enzymes that normally 22 occurs with phagocytosis of indigestable particles. The resulting local degradation of collagen may then stimulate fibro24 a s blast activity, or there may be a specific fibroblast-stimulating factor released by the macrophage.25 5) Acute, high-dose exposure to NO, produces an interstitial edema and later interstitial fibrosis. Both of these processes are likely to affect lymphatic drainage and the interstitial migration of particle-bearing macrophages. , These changes would most probably impede clearance and favor local accumulation of particles in plaques. 6) Experimental exposure to NO, appears to reduce resistance to pulmonary infection by both bacterial and viral pathogens. This probably occurs as a result of impaired mucociliary clearance and reduced phagocytic function. NOj also appears to inhibit intracellular killing by the halogen peroxidase system and the secretion of interferon by macrophages. Thus, the NO?-exposed lung 428 may be more vulnerable to secondary Infection. This In turn may alter the response to inhaled particles by its own effects. This approach to the problem of altered pulmonary responses is not well documented at present. The mechanisms discussed above may reasonably be expected to result in increased retention of particles in the lung and increased damage and fibrosis, but these sequelae have not been proven in studies to date. In unusual circumstances, a phenomenon of competing toxicity may act to reduce lung damage by a fibrogenic dust. Aluminum metal powder is thought to inhibit pulmonary fibrosis due to silicosis by competing with silicic acid in toxicity to the alveolar macrophage or fibroblast. Although both agents poison the electron transport chain in oxidative phosphorylation at cytochrome c, the aluminum ion is less toxic and appears to be a competitive inhibitor, resulting in a protect27 ive effect. The same phenomenon might exist when exposure to low concentrations of NCU accompanies inhalation of fibrogenic dusts; this could explain the unexpected protective effect ob12 served by Gross et al. and the lack of an increased tissue reaction to anthracite dust reported by Daniel-Moussard and colleagues. q This is speculation; the pertinent experiments remain to be done. These speculations on the possible role of N 0 2 in altering the pulmonary response to inhaled particles derive from the small number of directly applicable studies and inferences from the known pathophysiology of toxic inhalation. The question is ripe 3 18 for exploration using more sophisticated morphologic, ' 429 morphometrio, ' and functional techniques that have be- come available in the last few years. A systematic approach using various concentrations of gas and particles, comparing the effects of different gases and different dusts, and using different species with variations in lymphatic and vascular anatomy would add greatly to our understanding of the pathophysiology in actual occupational exposures. In the meantime, reporting the results of environmental monitoring for toxic gases as well as for particulates in the workplace may give us a more realistic picture of occupational lung disease. 43o References 1. Gu1dott1 TL. 1978. The higher oxides of nitrogen: Environ Res 15:443-472 2. Jones GR, Prou dfoot AT, Hall J I . 1973. Pulmonary effects of acute exposure to nitrous fumes. Thorax 28:61-65 Gu1dott1 TL, Abraham JL, DeNee PB, Smith JR. 1978. Arc welders' pneumoconiosis: \Appl1cation of advanced scanning electron microscopy. Arch Environ x Hea th 33:117-124 3. Inhalation toxicology. 4. Kennedy MCS. 1972. Nitrous fumes and coal miners with emphysema. Hyg 15:285-300 5. Guldotti TL. 1978. Coal workers' pneumoconiosis and medical aspects of coal mining. South Med J , 1n press 6. Jorgensen H. 1970. Studies on pulmonary function and respiratory tract symptoms of workers In an Iron ore mine where diesel trucks are used underground. J Occup Med 12:348-354 7. Boren HG. 1964. Carbon as a carrier mechanism for I r r i t a n t gases. Arch Environ Health 8:119-124 Furiosi NJ, Crane SC, Freeman G. 1973. Mixed sodium chloride aerosol and nitrogen dioxide in a i r . Arch Environ Health 27:405-408 8. Ann Occup 9. Daniel-Moussard H, Martin JC, Le Bouffant L. 1970. Etude expérimentale de l'action des vapeurs nltreuses sur le poumon empoussléré. Poumon Coeur 26:905-915 10. Lewis TR, Campbell K l , Vaughan TR Jr. 1969. Effects on canine pulmonary function via Induced N0? impairment, particulate Interaction, and subsequent SO . Arch Environ Health 18:596-601 Gardner LU, McCrum DS. 1942. Effects of dally exposure to arc welding fumes and gases upon normal and tuberculous animals. J Industr Hyg Toxicol 24:173-182 Gross G, et a l . 1968. Experimental emphysema: Effect of chronic nitrogen dioxide exposure and of papain on normal and pneumoconlotic lungs. Arch Environ Health 16:51-58 Sachs DPL, et a l . 1978. Macrophage resistance to hypotonic. Intracellular edema (Abstract). Am Rev Resp D1s 117Suppl.:389 (Presented to the American Thoracic Society Annual Meeting, Boston, 16 May 1978.) 11. 12. 13. 14. 15. van Allen CM, et a l . 1930. Gaseous interchange between adjacent lung lobules. Yale J Biol Med 2:297-300 Gu1dotti TL, Llebow AA. 1977. Toxic inhalation of nitrogen dioxide In canines. In Proceedings of the International Conference on Photochemical Oxidant Pollution and Its Control, Raleigh, North Carolina, 12-17 September 1976. US Environmental Protection Agency, Washington DC. 16. Welbel ER, Kistler GS, Scherle WF. 1966. Practical stereologlcal methods for morphometric cytology. J Cell B1ol 30:23-38 17. Morgan WKC. 1975. The disposition and clearance of dust from the lungs. In Occupational Lung Diseases, Ed. Morgan WKC, Seaton A. Philadelphia, W.B. Saunders Co., pp. 20-28 431 18. Sorokin SP, Brain JD. 1975. Pathways of clearance in mouse lungs exposed to Iron oxide aerosols. Anat Record 181:581-626 19. Guidotti TL. 1978. Breaching host defenses in the normal respiratory tract. Bull Soc Pharmacol Environ Pathol, In press 20. von Nieding G, et a l . 1970. Akute Wirkung von 5 ppm NO» auf die Lungenund Kreislauffunktion des gesunden Menschen. Int Arch Arbeitsmed 27:234-243 21. Rynbrandt D, Kleinerman J . 1977. Nitrogen dioxide and pulmonary proteolytic \enzymes. Arch Environ Health 32:165-172 22. Unanue ER. 1976. 83:396-417 Secretory function of mononuclear phagocytes. Am J Pathol White RU, Lin HS, Kuhn C I I I . 1977. Elastase secretion by peritoneal exudation and alveolar macrophages. J Exper Med 146:802-808 Postiethwalthe AE, Seyer JM, Kang AH. 1978. Chemotactic attraction of human fibroblasts to type I , I I , and I I I collagens and collagen-derived peptides. Proc Nat Acad Sci USA 75:871-875 25. Leibovich SJ. 1978. Production of macrophage-dependent fibroblast-stlmulating activity (M-FSA) by murine macrophages. Exper Cell Res 113:47-56 26. Bergström R, Rylander R. 1977. Pulmonary injury and clearance of MnO, particles. In Pulmonary Macrophages and Epithelial Cells (Proceeaings of the 16th Annual Hanford Biology Symposium, Richland, Washington, 1976), Ed. Sanders CL et a l . Springfield, Virginia, National Technical Information Service, No. 760927, pp. 523-532 27. Guidotti TL. 1975. Pulmonary alumlnosls—A review. Bull Soc Pharmacol Environ Pathol 3:16-18 Goldstein E, et a l . 1976. Methods for evaluating the toxicological effects of gaseous and particulate contaminants on pulmonary microbial defense mechanisms. Annual Rev Pharmacol Toxicol 16:447-463 28. 432 ¿Desempeñan los óxidos elevados de nitrógeno un papel en la alteración pulmonar como consecuencia de la agresión? T. L. Guidotti (Estados Unidos) Las reacciones tisulares a los polvos Inhalados, que constituyen la neumoconiosis. pueden modificarse considerablemente mediante una exposición simultánea a otros agentes inhalados no particulados. En las operaciones de soldadura, actividades agrícolas y el uso de explosivos en las minas, se ha comprobado la exposición a los óxidos de nitrógeno y probablemente coexistan con la Inhalación de partículas. Los anteriores estudios de la exposición combinada en los animales hacen pensar que se produce un efecto adicional con las partículas fibrógenas que acarrean la fibrosis pulmonar. En nuestros estudios, mediante una técnica experimental de intubación bronquial, se obtuvo la oxigenación unilateral con 37 ppm N02 en 5 perros. Comparando el pulmón expuesto con el pulmón contralateral no expuesto del mismo animal mediante técnicas fisiológicas y morfométrtcas se comprobó un ingreso reducido de oxigeno jy cambios intersticiales y endotellales precoces en el pulmón expuesto. Estos cambios son de tal magnitud que pueden alterar la disposición y la reacción del pulmón a las partículas inhaladas. Se recomienda proseguir los estudios para descubrir la modificación de las reacciones pulmonares a las partículas inhaladas de otros inhalantes exógenos. 433 The effect of the combined application of cadmium and lead sulfide and coal dust on the development of lung fibrosis In rats. J. Rosmanlth, R. Leonardi, D. Prajsnar, H. Brelning and W. Ehm Abteilung Hygiene und Arbeltmedizin der Rheinisch-Westfälischen Technischen Hochschule Aachen and Institut für Pathologie I der Bundesknappschaft am Knappschaftskrankenhaus In Essen-Steel, Federal Republic of Germany Introduction In experiments In which the rats were exposed to quartz with coal dust, a decrease of the flbrogenlc effect of quartz was observed (ref. 1,2). With the decrease of quartz content In the coal, the duration of the protective effect of coal Increased (ref. 3). This effect of coal is first of all due to argllaceous earth minerals (for Instance llllte) (ref. 3). It Is known that coal Includes also pyrites, I.e. disulfides of some metals. The experimental results we have hitherto, obtained Indicate the flbrogenlc effect of cadmium sulfide as well as of lead sulfide In the animals (ref.4,5). A synergistic reaction between cadmium and lead has been demonstrated (ref.6-10). We will therefore test In experiments whether the slmulta' neous application of cadmium and lead sulfide with or without coal dust Involves an increasing flbrogenlc effect. Methods In the first series of experiments, 240 female Wlstar rats with an average body weight of 200 g were administered 435 Single Intratracheal injections of cadmium sulfide and lead sulfide as suspensions in 0.5 ml saline solution separately or in combination (see Fig. and Tables). The various groups of ani- mals were killed after 4, 8, 12 and 16 weeks. The typical parameters of the fibrogenie effect in the lungs and regional lymph nodes i and the concentrations of cadmium and lead in these organs were determined. ly examined. The lungs and lymph nodes were also histological- The methods used are described in detail in other papers (ref. 4.5). Results An increase in lead dose with an equal dose of' cadmium results in a decrease of the cadmium concentration in the animals' lungs, with increasing cadmium doses at equal doses of lead a decrease in lead concentration was observed (Table 1 ) . After separate application of 50 mg CdS, the cadmium content in the lungs was found to be higher than after combined administration of CdS and PbS. The cadmium concentration in the regional lymph nodes was found to be higher.after combined administration of CdS and PbS, than after separate administration of cadmium sulfide (Table 2). The additional lead dose seems to accelerate the elimination of cadmium from the lungs into the lymph nodes. Lead increases the lymphotropism of cadmium. A similar influence was found for the lead concentration in the lungs and lymph nodes of the animals; the additional cadmium dose accelerated the elimination of lead from the lungs into the lymph nodes (Table 2 ) . 436 The biological parameters of effect, such as wet weight of lungs, dry weight of lymph nodes, content of oxiprolin and lipids were influenced rather by the cadmium dose, however the differences after 12 weeks have not always been significant (Table 3). The histological examination clearly showed an increased fibrogenic effect of the administered dust mixture. After the administration of 30 mg CdS and 15 mg PbS the lung fibrosis was more distinctly and earlier detectable than after the single dose of 50 mg CdS. After a relatively short time a considerable fibrogenic effect with the confluence of fibrous foci was observed (Fig'. 1). The lung fibrosis occurs rather in a focus-like than diffuse way and is also quite early detectable in the regional lymph nodes (Fig. 2 and 3 ) . In the second series of the experiment, the fibrogenic effect of the two metal compounds was examined in the presence of coal dustt 90 Wistar rats with an average body weight of 200 g were administered, by injection, single or repeated doses of 15 mg or 30 mg coal dust (anthracite coali 6,7% ash, 10,8% volatile Ingredients, 0,65% quartz) without or In combination with cadmium sulfide and/or lead sulfide. killed. After 6 months all the animals were The following examination was performed in a similar way as in the first series. The dry weight of regional lymph nodes increased, especially after simultaneous administration of cadmium sulfide and coal dust (Table 4 ) . The cadmium content in the lungs and lymph nodes depended on 437 the type of administration! when the various ingredients of the mixture were applied successively in single doses (independent of the order)i an increased elimination of cadmium from lungs into regional lymph nodes was observed (Table 4). The repeated application of smaller doses increased the lymphotropism of the mixture» It was shown again that lead, even in the presence of the coal dust, influences the lymphotropism of cadmium. After combined application of coal dust and lead sulfide, the lead content in the lungs was lower, when the two ingredients were applied simultaneously (Table 4 ) . The presence of coal seems to disturb the influence of cadmium on the increasing elimination of lead from the lungs. The behaviour of lead sulfide in the presence of coal is in any case quite different from that of cadmium sulfide. Neither the application of pure coal dust nor the simultaneous application of coal dust and lead sulfide led to fibrogenic changes in the lungs or in the lymph nodes. Even after threefold repeated injection of 5 mg lead sulfide and subsequent application of 30 mg coal dust in 10 animals, a slight fibrosis in lung parenchyma was recognisable only in one case. Otherwise after simultaneous application of 30 mg coal dust and 15 mg cadmium sulfide, in all animals a slight focus-like fibrosis in both lungs and lymph nodes was observed (Fig. 3 ) . After intratracheal injections of 15 mg lead sulfide, 15 mg cadmium sulfide and 15 mg coal dust, successively applied at three days' intervals, a distinctly to heavily focus-like or diffuse fibrosis in lung parenchyma was identified (Fig. 4 ) . 438 ( 1) Dolgner.R., rjchlipköter, H.V.". und Leiteritz,H. : Tierversuche zur Bedeutung des Inkohlungsgrpdes und Tonminerale für die Uewetsreaktion auf Quarz. Silikose-Bericht Iiordrhfin-Westfalen, Bd 7,Bösmann-Verlag Detmold,1969, S.45-49. ( 2) Martin, J.C., Daniel-Moussard,H., LeBouffant.L. and Policard,A.: The role of quartz in the development of coal workers pneumoconiosis. Ann.N.Y, Acad.Sci. 200, 127-141 (1972). ( 3) LeBouffant,L., Daniel, H. und Martin,J.C.: Die Rolle des Quarzes bei der Bildung pneumokoniotischer Läsionen beim Steinkohlenbergarbeiter. • Kommission der EO, Schriftenreihe Arbeitshygiene und Arbeltsmedizin Nr 19, Luxembourg 1977. ( 4) Breining,H|,-.J.Rosmanith und Prajsnar,D.: Lung fibrosis in rats after cadmium sulfide application. Proceed. of the Vth Internat. Conference on pneumoconioses, Oct. 29-Nov.,3, Caracas, 1978. . ( 5) Prajsnar,D.,Breitling,H. and Rosmanithjil*: Lung fibrosis after lead sulfide application^. Proceed. of The Vth Internat.Conference on Pneumoconioses, Oct.,29 - Nov.,3, Caracas, 1978. ( 6) Ferm, V.H.: The synteratogenic *i'feet- Vf lead and cadmium. Experlentia 25 i 5 6 * 5 7 (1969). ( 7) Chailop, R.S.: Role of cadmium in léatí poisoning. New Engl.J.Med. 285, 970-971 (1971)¡i, ( 8) Chisoìm, J.J.t Heavy metal exposurei toxicity from metal-metal Interactions, and behavioral effects. Pediatrics 53, 841-843 (1974). ( 9) Rosmsnith, J., Elnbrodt, H.J. und Ehm, W.: Zu Interaktionen zwischen Blei, Cadmium und Zink bei Kindern aus einem Industriegebiet. StaubReinh.Luft 36, 55-62 (1976). (10) RosmanlthjJ., Pistorlus, D., PraJsnar,D. und Ehm,W.: Darstellung von Interaktionen zwischen Blei, Cadmium und Zink (Tierversuche). 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U I-l « O ho S O + 1x (10mg coal en g coal) O • X X ï ~ »- C (. Efecto de la aplicación combinada de sulfuro de cadmio v de plomo v polvo de carbon en el desarrollo de una fibrosis pulmonar en las ratas. J. Rosmanith, R. Leonardi y D. Prajsnar, H. Breining y W. Ehm (República Federal de Alemania) Se aplicaron simultáneamente por vía intratraqueal en hembras de rata Wistar diferentes dosis de sulfuro de cadmio y de plomo en suspensiones. Este procedimiento provocó una fibrosis tanto en el parénquiraa pulmonar corao^en los nodulos linfáticos de la region. El efecto fibrógeno no dependía de la dosis total de sulfuro de cadmio y de plomo. Una dosis inferior de una aplicación combinada de CdS + PbS llevó a un efecto más fibrógeno que la dosis más elevada de CdS o de PbS aplicadas separadamente. También se descubrió la fibrogeneidad de ambos compuestos metálicos en presencia de polvo de carbón, pero se observaba un efecto aumentado al aplicarse sucesivamente estos tres materiales. 445 LUNG FIBROSIS IN RATS AFTER LEAD SULFIDE APPLICATION D. Prajsnar, H. Brelning, and J. Rosmanith Abteilung Hygiene und Arbeitsmedizin der Rheinisch-Westfälischen Technischen Hochschule Aachen, Federal Republic of Germany Introduction Lead sulfide Is a constituent of some lead ores, copper ores and of various types of coal (ref. 1-3). An Increased content of lead was also found In the silicotic lungs of coalmlners as well as of dead lead ore miners with the Increase of the S10 2 content (ref. 4-8). To clarify the possibility of the fibrogenlc effect caused by the compounds of lead (ref. 9-14), the effect of the lead sulfide on the rats was examined. Methods 60 Female Wlstar rats were divided into 3 groups i rats of the first group were administered intratracheally a single injection of 15 mg PbS as suspension in 0,5 ml saline. Rats of the second and third groups, were similarly treated with 30 mg PbS and 50 mg PbS, respectively. After 12 weeks all the animals were killed. The lungs including the regional lymph nodes were removed. The right upper lobe of the lung was examined histologically after embedding in paraffin and stained with HE and EvG. 447 The remaining lung tissue was chemically processed, and the following components were quantitatively determinedi total content of oxiprolin (ref. 15), all lipids both total and fractured to this lead (ref. 16), contents of phospholipids, into lecithine (ref. 17-18). In addition was also quantitatively determined (ref. 19). Results It was found that the wet lung weight, the content of lead and oxiproline in the lungs and the content of lecithine, total lipids and total phospholipids (Table 1) increased with the PbS dose. The relative concentration of lead in the lungs remains the same independent of the dose. The content of oxiproline, total lecithine and total phospholipids found after12 weeks in the rats treated with 50 mg PbS remains slightly lower compared to that after the application of CdS (ref. 20)i on the other hand, the wet lung weight, the weight of the lymph nodes and the content of total lipids were remarkable lower than those found after application of CdS. The results of the histological examination agree with the biochemical parameters! 12 weeks after the application of 15 mg or 30 mg PbS deposits of the black-brown pigment (with a light foam reaction of the cells) was recognised in the lungs, but no fibrosis was found. 12 Weeks after the application of 50 mg PbS, brown-black pig- ment was nodularly deposited showing partially tuberculoid reaction and containing single giant cellst in addition the cells showed a distinct fibrogenic effect with collagene fibres. The fibrosis of the lungs is either nodular (Fig. 1) or diffuse (Fig. 2). Small amounts of brown pigment without any cellular reaction were found in the regional lymph nodes. 448 References (1) Baum, Ch.: Quantitative und qualitative Untersuchungen zur Staubretentior. in den Lungen schwedischer ¡irzbergleute. Diss.-Arbeit, Medizin.Fak. RWTH Aachen, 1973. (2) Crable, J.V., Keenan, R.G..Wolowicz, F.R.,Knott,M.J., Holtz,J.H. & Gorski, C.H.: Metal and mineral concentrations in lungs of bituminous coal miners. Amer.Ind. Kyg.Assoc.J. 29, 106-110 (1968) (3) Sorenson, J.R., Kober,T.H. & Petering,H.G.: The concentration of Cd, Cu, Fe, Ni, Pb and Zn in bituminous coals from miners, with differing incidences of coal workers pneumoconiosis. Amer. Ind.Hyg.Assoc.J. 35, 93-98(1974) (4) Thomas, R.W. & Cummins,S.L.; Acute silicosis in leadminers. Lancet 233, 1481-1484 (1937) (5) otbfen, D.: Die Rolle des Bleis in der Pathogenese der Silikose. Arch. Hyg. 153, 478-482 (1969) 45o ( 6) Knagge-Ruhe,B., Stecher, W. & Einbrodt,H.J.: Lungenveränderungen bei Arbeitern nach Bleierz- und Bleiexposition. Beitr. Silikose-Forsch.(Pneumokon.) 23, 156-171 (1971) ( 7) Einbrodt,H.J., Kinny.H. & Kortemme.H.: Quantitative Untersuchungen über den Lymphtransport von Blei aus der menschlichen Lunge. Arch.Hyg. 153, 105-108 (1969) ( 8) Kinny, H. & Einbrodt.H.J.: Quantitative Untersuchung in den Lungen von Bergarbeitern mit Silikose. Arch. Gewerhepath.^ewerbehyg. 25, 1-14 (1968) , ( 9) Eingham,E., Pfitzer.E.A., Barkley,V.". & Radford,2.P.: Alveolar macrophages: reduced number in r ts £u"ter prolonged inhalation oí lead sesquioxide. Science 162, 1297 (1968) (10) Glitz,E., Kinny,H. & Einbrodt.n.J.: Zur Erythrozytenschädigunc durch Jleistäuben. Int.Arch.Arbeitsirod. 26, 321-329 (1971) (11) Sanders,Ch..L.', ¿dee,«.it. U Jackson,T.A. : Fine structure of alveolar areas in the lung following inhalation of 239FU0, particles.Arch.Environm.Health 22, 525-533 (1971r (12) Bruch,J., Brockhaus,A. & Dehnen,Y/.: Elektronenmikroskopische Beobachtungen an Rattenlungen nach Exposition mit partikelförmigem Blei. In: Environmental Health Aspects of Lead. Proceedings of a symposium held in Amsterdam ,0ct. 2-5 (1972), pp.221-229 (13) Beck,E.G.,. Mano;)lovic,N. & Fischer,A.B. : Die Zytotoxizität von Blei. In: Environmental Aspects of Lead. Proceedings of a symposium held in Amsterdam, Oct. 2-5 (1972),pp. ¿451. (14) Kyono,H.,Homma, K., r¡agatani,T., Watanabe,T. & Kawai, K.: Localization of inhaled lead particles in the rat lung. Ind.Health (Jap.)12, 49-72 (1974) (15) Stegemann,H.: Mikrobestimmung von Hydroxyprolin mit Chloramin-T und p-Dimethylamlnobenzaldehyd. HoppeSeyler's Z.physiol.Chem. 311, 41-45 (1958) (16) Folch,J., Lees,M.. & Sloane,S.: A simple method for the isolation and purification of total lipids from animal tissues. J.Biol.Chem. 226, 497-509 (1957) (17) Brockmann,U. & Gercker,E.: Quantitative eindimensionale Dünnschichtchromatographie der Erythrozytenphospholipide. Clin.Chim.Acta 23, 4S9-494 (1969) (18) Fiske,C.H. & Subbarov/,Y.: The colorimetrie determination of phosphorus. J.3iol.Chc:n. Co, 375-^0 0925) 451 (19) Hachata,G. & Binder,R.: Bestimmung von Blei-, Thalium-, Zink- und Cadmiumspuren in biologischem Material mittels flamraenloser Atomabsorption. Ztschr.Rechtsmedizin 73, 29-34 (1973) (20) Brelning,H., Rosmanith,J. & Prajsnar.D.: Lung fibrosis in rats after cadmium sulphide application. 452 ^ ^ « » ^ »— t^- 10 t co bo bo-o i: TT- ß -H P 3 CXrH •J - H ^ iH M • ^ E IO CO <f o » r^ •J- vO a» IX -Ï ' ^ Ol bO •Ö C • H P OA m bO c 3 ^t vo <T> CT> CM IM - í ^t * •* •» r 4 VD o) Vi O .p O"-* ß 0) bO-H S . Oft. ->\C Pif-i w o •* IX IO IO .fi 3 VO p. - -• — ITO- ss hO-HrH C Ä~-^ 3-POu j » ( O H <u o T- CM T- O CM -í <t <t en a\ ~ o t— T- CM o O « ß •H CT\ a\ -*- Ix CO fcO T IO I• O " • O CO • " VO « O X) ß -O H p, I— O - *— Tj - ro ho C O o CM CM Ii O o O I O I— — 26, OS io io CM o p. V) 1 *— a» o ~ « v- 4) S?^ S ' ß O 3 3 t r H •4 f V v . • H bO x B o T- VO 0\ CT> co co m « . . . Ix w IO IO cu CD H fi (0 EH +> .fi r bO •H'-> > <0 io C^ « O io T« O 00 IO « CO • Í IO. O IO IO T- f i -H £ +> -H o co ufi H CU » 0) ß -H H O <H O fi >» n a 3X1 3 •JdirH bo IX . . . . r- x- in '"*> «0 § M O a) o »H rH a • o a) oo t>- CM i» O N O K\ . O CO ~ CO CO r- VO ¿3 -O U to o M O S p li t - . CM (M CU CO CO fi fi fi +• « fi ^ .a. a. hfl . - . . -bfl. E E IO E 0) r-l VO r - , CM (M hO E - ; - . - • . +• CU .fi +> r- " " ß »H X O PbS E +J .C bt) t bo-ri - cu •i * *-l CU ï AI 1 O OE OE IO in x x x <H O +J fi bO -p e Fibrosis pulmonar en las ratas previa aplicación de sulfuro de plomo. D. Prajsnar, H. Breining y J. Rosmanith (República Federal de Alemania) Se aplicaron por vía intracraqueal en hembras de rata Wistar suspensiones de 15, 30 y 50 mg PbS. Este procedimiento llevó en 12 semanas a una fibrosis pulmonar dependiente de la dosis PbS. Se descubrió una estrecha relación entre la dosis y el aumento del peso húmedo del pulmón o del contenido del pulmón en oxiprolina. La lecitina, los fosfolípidos totales y lípidos totales del pulmón de las ratas aumentaron también con la dosis. 454 Lung fibrosis In rats after cadmium sulfide application H. Breining, J. Rosmanith and D. Prajsnar Institut für Pathologie I der Bundesknappschaft am Knappschaftskrankenhaus in EssenSteele and Abteilung Hygiene und Arbeitsmedizin der Rheinlsch^WestfälIschen Technischen Hochschule Aachen. Federal Republic of Germany Material and Methods 72 Wistar rats with an average body weight of 200 g were divided into 3 groups« A dose of 15 mg cadmium sulfide sus- pended in 0,5 ml saline solution was administered once by intratracheal injection to the first group of animals« By the same method, the animals of the second group received a single dose of 30 mg, and the animals- of the third group a single dose of 50 mg of cadmium sulfide. ether. All animals had been anaesthetized with The 24 animals of each group were killed 4 weeks, 8 weeks and 12 weeks after administration of cadmium sulfide« The lungs including the regional lymph nodes were removed. The right upper lobe of the lung was examined histologically after embedding in paraffin and stained with HE and EvG. The remaining lung tissue was chemically processed, and the following components were quantitatively determinedi total content of hydroxyprolin, all lipids, contents of phospholipids, both total and fractured into lecithin. In addition to this, cadmium was also quantitati- vely determined. Results The results of this analysis are represented in Tables l-4i 455 Groups two and three, having received a dose of 30 mg and 50 mg respectively, show a significant increase in the wet and dry weights of their lungs dependent on dose and duration of experiment. An analogous trend is shown by the dry weight of the regional lymph nodes. The total content of hydroxyprolin correlated more to the duration of the experiment that to the dose. Not until after a period of 12 weeks a close correlation could also be noticed to the dose of the administered cadmium sulfide. The same was true with the total content of phospholipids and the other lipid components of the lungs i 12 weeks after the beginning of the experiment a close correlation started to establish itself to the received cadmium dose. length of the experiment, close Independent of the correlations existed between the cadmium concentration of the lungs and the lymph nodes and the weight of the lungs, as well as positive correlations between the cadmium concentration and the lecithin concentration in the lungs of the animals. The lungs of the animals showed abundants deposits of finegrained brown or black pigments. In addition, an inflammatory infiltration of varying degree, consisting mainly of leucocytes, could be seen, especially in the deposits. neighborhood of the pigment In some cases, the inflammation had caused distinct confluence reducing the still functioning lung parenchyma to a minimum. Four weeks after the beginning of the experiment an increase of collagen fibers could be microscope. noticed under the light 8 Weeks after administration of cadmium sulfide, an increasing fibrosis of the lung parenchyma could be proven 456 Independent of the dose given. The fibrosis was distinctly noticeable four weeks after administration of 30 mg of cadmium sulfide. 8 Weeks after administration of 50 mg of cadmium sulfide, the fibrosis of the lungs was quite Intensive showing sections of diffuse fibrous tissue. The collagen fibers showed as broad bright red bands after staining with EvG without nucleus, partly forming a network and in the net structures still showing the described deposits of pigments (Fig. 1 ) . In some cases the lung fibrosis was, even after a dose of 50 mg of cadmium sulfide, more local or clrcumscript. Some lungs presented groups of foam cells, especially In the neighborhood of the pigment deposits. No fibrogenic reaction was seen in any of the lymph nodes. Our investigation has proved a distinct fibrogenic reaction of the rat lung to the administration of cadmium sulfide dependent on the length of time of having been In the organism as well as on the dose given. 457 Reforonces (1) Piske, C.H. and Subbarow,Y.: The colorimetrie determination of phosphorus. J. Biol. Chem. 66,375-400 (1925). (2) Folch,J., Less,M. and Sloane.S.: A simple method for the isolation and purification of total lipids from animal tissues. J.Biol.Chem. 226, 497-509 (1957)- (3) Grünspan,M., SchlLpköter,H.W. und Antweiler,H.:Ein neues Kriterium für die biologische Wirkung von quarzhaltigen Stäuben. Silikose-Bericht NRW,Bd 9, 137-140 (1973). (4) Kaw,J.L.,Gupta,G.S.D and Zaidi.S.H.: Lung lipids and pulmonary silicosis in rats. Int.Arch.Gewerbepath. Gewerbehyg. 27, 324-330{1971). Kyselá,B., Jirakov4,D., Holusa,R. and Skoda,V.: The influence of .the size of quartz dust particles on the reaction of lung tissue. Ann.Occup.Hyg. 16,103109 (1973). (5) (6) Löblich,H.J.: Quantitative Untersuchungen über die Entwicklung der experimentellen Silikose. Beitr. Silikose-Forsch., H.78, 1-18 (1963). (7) Hachata,G. und Binder,R.: Bestimmung von Blei?Thalium-, Zink- und Cgdmiumspuren in biologischem Katerial mittels flammenloser Atomabsorption.Zschr.ßechfcsmed. 73, 29-34 (1973). (8) Marks,G.S. and Karasas.L.W.: Change in the lung lipids of rabbits and guinea-pigs exposed to the inhalation of silica dust. Brit.J.industr.''ed. 17, 31-35 (1960). (9) Paterson.J.C: Studies on the to^icifcy of inhaled cadmium. J. Ind.Hyg.Toxicol. 29, 294-301 (1947). (10) RosmanithjJ. und Breining,H.: Beschleunigung der Entstehung von experimentellen Lungenfibrosen nach intratrachealer Applikation von Cacimiumsulfid und Kohlenstaub. Beitr. Silikose-Forsch.(Pneumokon.) 27, 11-16 (1975). (11) Stegemann,H.: Hikrobestimmung von Hydroxyprolin mit Chloramin-T und p-Dimethylaminobenzaldehyd. HoppeSeyler's Zschr.Physiol.Chem.311,41-45 (1958). 458 Table 1. Wetweight of the lungs and dry weight of the regional lymph nodes according exposure and dose I i Lung mg wet weiqht Mean Lymph nodes mq dry weiqht Mean SD 1x15 mg CdS 1911.43 521.78 26.07 Application 9,57 1x30 mg' Cds 1698.75 342.03 22.69 7.79 1x50 mg CdS 2184.57 473.63 38.18 15.09 1x15 mg cas 2056.25 529.39 30.21 20.60 1x30 mg cas 2283.56 392.32 43.28 18.87 33.75 1x50 mg CdS 2277.50 376.93 54.99 1x15 mg CdS 2341.67 ,474.65 22.49 1x30 mg CdS 2904.75 461.78 46.87 19.35 1x50 mg CdS 413.80 479.27 65.92 26.44 459 6.95. Table 2. Concentration of cadmium in the lungs and in the lymph nodes according exposure and dose I Application Lung (mg Cd/g dry weight) Mean SO Lymph nodes (mg Cd/g dry weiqht) Mean SD 1x15 mg CdS 16,02 5,37 9,72 3,49 1x30 mg CdS 45.29 27.24 15.96 11.14 1x50 mg CdS 31.62 16.17 4.03 2.03 1x15 mg CdS 14.46 10.15 10.80 12.76 1x30 mg CdS 25.74 12.93 25.47 17.36 1x50 mg CdS 36.40 24.41 39.88 20.28 1x15 mg CdS 13.48 5.38 10.03 3.36 1x30 mg CdS 29.72 5.43 41.87 15.12 1x50 mg CdS 43.21 6.89 51.18 14.57 Table 3. Hydroxiprolin and lecithin content in the lung of rats according exposure and dose Application Hydroxiprolin (mg/lung) Lecithine (uMol P/lung) Mean SD Mean 1x15 mg CdS 3,84 0.14 19.37 4.94 1x30 mg CdS 3.46 0.68 19.70 6.61 1x50 mg CdS 4.79 1.61 26.88 11.61 1x15 mg CdS 4.82 1.37 15.11 4.95 1x30 mg CdS 4.97 1.27 17.49 5.83 1x50 mg CdS 4.71 1.39 18.38 3.86 1x15 mg CdS 6.18 2.24 13.37 4.44 1x30 mg CdS 8.05 1.20 18.84 4.05 1x50 ng CdS 9.10 1.77 27.09 6.74 46o SD Table 4. Total phospholipids and total lipids in the lung of rats according sxposure and dose H c Application Phospholipids fyuMol P/lung) Total lipids (jUMol P/lung) 1x15 mg CdS 35.77 73.46 16.16 1x30 mg CdS 35.73 12.31 57.38 14.25 1x50 mg CdS 45.80 13.80 75.70 21.27 7.50. 1x15 mg CdS 30.23 8.55 50.62 13.58 1x30 mg CdS 33.56 9.37 81.47 26.06 1x50 mg CdS 33.10 6.32 65.87 13.37 1x15 mg CdS 29.76 13.85 57.74 18.59 1x30 mg CdS 37.64 5.86 67.98 9.30 1x50 mg CdS 62.27 9.75 80.11 14.12 461 Fibrosis pulmonar en las ratas previa aplicación de sulfuro de cadmio. H. Breining, J. Rosmanith y D. Prajsnar (República Federal de Alemania) Se aplicaron por vía intratraqueal en hembras de rata Wistar suspensiones de 15, 30 y 50 mg CdS. Este procedimiento provoco en el curso de 4 a 12 semanas la evolución de una fibrosis pulmonar dependiente de la dosis de CdS y de la duración del experimento« Se descubrió una estrecha relación entre la ^dosis y todos ^los parámetros del efecto fibrógeno (peso húmedo del pulmón, peso seco de los nodulos linfáticos, contenido en oxiprolina, fosfolípidos y lípidos en el pulmón). 462 I N D I C E VI. I S E S S I O N VI . Y.Hosoda., N.Salto., T.Kono., H.Ohteke and V.Chiba Epidemiology of asbestos-induced pleural thickening VI. II m.L .Nenihouse Asbestos-related diseases in relation to type of ocouoatIon. VI. III Ruth Lilis., and J.Selikoff. Asbestos disease In maintenance workers of the chemical Industry. VI. IV S.r.mcCullagh Biological effects of Asbestos - The unresolved matters VI. V VI. VJ UJ.Weiler Biological effects of Asbestos-Quartz dust-mixtures L.m.Lacquet., L.van dar. Linden., J.Lepoutre Prevalence of lung changes, and mortality In a belglan Asbestos-Cement VI. VII factory. A.Hirsch., L.Ol manza., HI.mangold., J.Blgnon Ridldlte dlaphragmatlque et exposition a l'amiante: Correlation radlologique et chirurgicale dans 47 thoracotomies. VI. Vili J.m.G.Davis., S.T.Beckett., R.E.Bolton.., Paula Collings. The Pathological effects of asbestos clouds of different fibre dimensions on the lungs of rats. 463 EPIDEMIOLOGY OF ASBESTOS-INDUCED PLEURAL THICKENING Y. Hosoda, N. Salto, T. Kono, H. Ohtake and Y. Chiba JNR Central Health Institute Yoyogl 2-1, Shibuya, Tokyo, Japan Introduction With the environmental Improvement of asbestos dust, the cases with severe pulmonary flbrotic lesions will decrease in number in the future. When people are exposed to low concentration of asbestos dust, pleural thickening is known as an important sign. With regard to the X-ray reading of pleural changes, however, no agreement is reached as to what is a lower limit change in the pleura for an ILO U/C standard film. Purpose The purpose of this study, composed of 2 parts, is to investigate a lower limit of pleural thickening caused by asbestos exposure. Part 1• Reading Results bv Readers' Impression Subject and method of study As an epidemiological approach to these problems, a control study was made of pleural thickening occurring in asbestosexposed and non-exposed workers. The former comprised 130 railway factory workers exposed to a low concentration of asbestos dust during their jobs of cutting and grinding asbestos slate or friction materials at present and repairing steam locomotives in the past. As a sex and age matched control, the same number of railway maintenance workers in a rural area was 465 used. We made a separate study on Tokyo clerks, but the prevalence of their pleural changes was higher that in the abovementioned control workers. The pleural changes were observed according to age and the duration of employment. It is said that obese people tend to present pleural thickening like shadows more often than slim people. As for the physical constitution of the subjects of the study, the workers generally had non-fatty muscular structure. The body weight of asbestos workers was much lower than that of the railway workers' average, while that of the controls was in the workers' average. X-ray films were taken in a PA direction and, when necessary, in oblique positions at lOOkV using 12il movable grid. As for the X-ray film reading, the PA films to be read were serially numbered according to random numbers, and the identity of the examinees was concealed for a blind reading. The films with the closure of the cost-phrenic angles were separately grouped in view of the possible tuberculous etiology and the recording was made according to localisations! in the lateral chest wall, along the ribs, on the diaphragma and over the lung field. The rib companion shadows produced by ribs themselves were excluded from the recording. The reading was based on the readers' comprehensive impression in combination with shape, width, density and localisations of the pleural changes, referring to the ILO U/C standard films. Results 1. No apparent pulmonary parenchymal lesions due to asbes- 466 tosis were found in the two groups« No pleural changes were seen on the diaphragma. 2. The closure of the cost-phrenic angles was found in 7 of 130 in the asbestos group (5.4%) and in 5 in the control group (3.8%). 3. The prevalence of pleural thickening increased with the advance in age and the length of employment. 4. The total number of cases presenting abnormal and suspected abnormal changes in the lateral chest walls and along the ribs was 19 in the asbestos group (14.6%) and 9 in the control group (6.9%), the difference being 5. significant (p¿0.05). The number of cases with abnormal changes was 11 in the asbestos group (8.3%) and 2 in the controls (1.5%), while the number of those with suspected abnormal changes was 8 in the asbestos group (6.2%) and 7 in the controls (5.4%). 6. Bilateral pleural changes were found in 11 of 19 asbestos workers and in 4 of 9 controls. The shadows along the ribs tended to appear more often on one side, while the costphrenic angle changes appeared on both sides in 11 of 12 cases. 7. The pleural changes along the ribs were located In the 7th and 8th ribs in almost all cases. 8. After reading all films, the width of pleural changes was measured by sliding callipers. The width of pleural changes in an ILO U/C standard film was 4mm. In the films regarded as abnormal, 15 to 19 had a width of 3mm or more, while in the films regarded as suspected abnormal, 3 of 11 had a width of 3mm or more. 467 The Impression well corresponded to the measurement. If one should venture to set a safe cutting point between normal and abnormal pleural changes only from the width viewpoint, it would be necessary to minimise false positive and false negative. In this respect, 3mm or more in width would be a tentatively acceptable lower limit. Discussion It should be remembered from the clinical point of view that any asbestos-induced pleural thickening starts at nil, reaching 3mm or more. The subjective reading of pleural changes along the lateral chest walls and along, the ribs usually gives discrepant results due to inter-observers' error. However, when the reading is repeated separately or jointly, there was a tendency of reaching a point of agreement. As for the cause of these pleural changes, further studies should be made not only on asbestos but also on other materials. Conclusion As for the pleural changes, 3mm in width along the lateral chest walls or along the ribs may be a'tentative criterion to minimise false positive and false negative. Part II. Reading Results Based on the Width Measurement Subject and method of study In the foregoing part I, a 3mm width was proposed as a lower limit for abnormal pleural changes based on the X-ray reading by readers' impression. The part II aimed to investi- 468 gate if the width measurement was useful in diagnosing pleural thickenings The subjects of the study were the same as in part I, and the X-ray reading was made by measuring the width of pleural changes by sliding callipers. In this study, any shadows along the lateral chest walls or ribs were recorded regardless of the origin of the shadows, including normal soft tissues« The changes were grouped into 2 according to the localisation. When the changes were situated along the lateral chest walls, they were categorised as type I and when they were along the ribs, they were placed in type II. The distinction of the two types was not essential, because a type II shadow in a PA film sometimes showed a type I shadow in an oblique radiograph. In this study, the distinction between the diffuse and localised (plaque) pleural changes was not made, as the width was only the parameter. In this railway company, recruits were limited to new graduates from schools, and the employees usually remained in the same jobs until retirement. For this reason, the duration of employment roughly corresponded to the age of the workers. In consideration of a possible age factor relating to the pleural changes, the observations were made according to age. Those over 40 years old numbered 62, and those aged 39 or less numbered 68. The prevalence rate was shown in the number of sides. Accordingly, the former group had 124 sides and the latter 136 sides. 469 Results 1. The prevalence of pleural changes was higher in the asbestos group that in the control group in both types; 54/260 (20.8%) in the asbestos group and 38/260 (14.6%) in the controls as regards type I, and 9/260 (3.5%) in the asbestos group and 4/260 (1.5%) in the controls as regards type II. If the changes with 3mm or more were consideredi the prevalence was 12/260 (4.6%) in the asbestos group and 4/260 (1.5%) in the controls as regards type I and 8/260 (3.0%) in the asbestos group and nil in the controls as regards type .II. This nil figure should not be generalised as the Tokyo clerks in our separate study had the changes over 3mm in type II. 2. When observations were made according to the two age groups, 40 years or more and 39 years or less, the older group had a higher prevalence rate than the younger group. As regards type I, the prevalence was 34/124 (27.4%) in the asbestos group and 22/124 (17.7%) in the controls in the older age group, while it was 20/136 (14.7%) in the asbestos group and 16/136 (11.8%) in the controls in the younger age group., With regard to type II, the prevalence was 9/124 (7.3%) in the asbestos group and 1/124 (0.8%) in the controls in the older age group, while it was nil in the asbestos group and 3/136 (2.2%) in the controls in the younger age group. The last group showed an exceptional result probably because the number observed was too small. When the distribution of the width was investigated between the asbestos and control groups, the difference in prevalence between the two groups became larger when the width exceeded 47o 3 or 4mm. However, in the 95% confidence limit in digit analysis, the difference was not significant. 3. As for the side of changes in type I( the ratio of right« left i both sides was 13t 9i16 in the asbestos group, while it was 8t6il3 in the controls. In short, about a half of the changes was found in both sides. 4. As for type II, the shadows appeared along the inferior edge of the posterior rib shadow with a rare exception and were most frequently found in the 8th rib followed by the 7th and 9th. Discussion If the asbestos group had been a little more heavily exposed, or if the asbestos group had had more number of cases with pleural changes, the difference might have been significant. At the same time, it should be considered that the control group had no evidence of freedom from asbestos dust exposure during their lives. At present, it would be no longer possible to find a group completely free from asbestos exposure. It should also be remembered that this method of study included the shadows produced by the physiological elements in the asbestos and control groups» Conclusion The asbestos-exposed group showed a higher prevalence of pleural changes than the control group in terms of the width of pleural changes. When the width exceeded 3mm or more, the 471 prevalence showed a large difference between the two groups. In the authors' opinion It may be safe to set a tentative screening line for pleural changes In PA films at 3mm or more, referring to the study in part I as well. 472 EPIDEMIOLOGIA DEL ESPESAMIENTO DE LA PLEURA PROVOCADO POR EL AMIANTO Informe Introductorio por Y. Hosoda, N. Salto, H. Ohtake y Y. Chiba (Japón) El objeto del estudio es Investigar cual es el límite inferior de espesamiento de la pleura en las radiografías. Para hacer más claras las características de espesamiento se excluyeron los casos con fibrosis pulmonar debida al amianto. Así, los trabajadores que habían estado expuestos al amianto en baja concentración fueron observados junto con trabajadores casi exentos de amianto, emparejados por sexo y edad. La incidencia de espesamiento de la pleura aumentó con la edad y con la duración del servicio en el grupo expuesto, y mostró una tendencia análoga en el grupo de control. Sin embargo, la incidencia fue más elevada en el primer grupo. Si se estiman en principio 3 mm como límite inferior de espesamiento de la pleura, la diferencia en la incidencia se acentuó en ambos grupos. Se intentó agrupar los tipos de espesamiento de la pleura en ores« el de pared lateral, el de costilla y el difuso. Es digna de mención la contracción de la caja torácica en el lugar del espesamiento pleural. 473 ASBESTOS-RELATED DISEASES IN RELATION * TO TYPE OF OCCUPATION (Summary) M. L. Newhouse United Kingdom The health risks of heavy and prolonged exposure to asbestos are now well recognised. There Is less knowledge of the degree of risk In different sections of the asbestos Industry. The literature In relation to asbestos-related diseases In mining, the manufacture of different products and the usage of asbestos-containing materials has been reviewed. There are mark- ed differences which will be demonstratedi but difficulties are experienced In evaluating these differences due to lack of uniformity In methods of investigation and Insufficient Information In many reports on method of dust control and levels of exposure. It Is, however, clear that processes Involving the use of crocldollté and amoslte asbestos carry a higher risk, particularly of mesotnellai tumours than that where only chrysotlle asbestos Is used. Crocldollte miners, textile workers amd Insulators or laggers are at the greatest risk. Asbestos cement workers, pro- bably the largest section of workers In the asbestos Industry, are believed to be at lower risk than Insulation or textile workers, but marked differences In mortality In different sections of this Industry have been demonstrated, probably dependent on the type of fibre Incorporated In the product as well as the degree of exposure. A study of the mortality of workers who have been engaged In production of friction materials Is now being undertaken, which Is 475 of particular interest as, apart from two short periods where crocidolite was used, the only exposure has been to chrysotile asbestos. Epidemiological studies in the asbestos cement industry and other sections of the industry such as those producing floor tiles and asbestos/plastic products, are needed. * The paper "in extenso" to be asked to the author. 476 Enfermedades derivadas del amianto en relación con el tipo de ocupación. M. L. Newhouse (Reino Unido) Actualmente se reconocen los riesgos que para la salud presenta una exposición importante y prolongada al amianto. En cambio, todavía se sabe muy poco sobre el grado de riesgos en los diferentes sectores de esa industria. La literatura sobre las enfermedades producidas por el amianto en las minas, la fabricación de diferentes productos y el uso de materiales que lo contienen ha sido puesta al dfa. Existen notables diferencias, que serán demostradas, pero también se tropieza con dificultades para evaluarlas, debido a la falta de uniformidad en los métodos de investigación y a la insuficiente información sobre métodos de control de polvos y niveles de exposición. No obstante, es evidente que los procesos que involucran la utilización de crocldolita y amosita presentan un mayor riesgo, en particular de tumores del mesotelio, que cuando se utiliza solamente el crisotilo. Los mineros de la crocidolita, los trabajadores textiles, los instaladores de material aislante o calorífigo son quienes corren los mayores riesgos. Se piensa que los trabajadores del cemento de amianto, probablemente los más numerosos en esta industria, corren menos riesgos que los trabajadores textiles o instaladores de material aislante, pero se ha demostrado que existen diferencias notables en la mortalidad en los diferentes sectores de esta industria, probablemente según el tipo de fibras incorporadas en el producto y según el grado de exposición. Se está haciendo ahora un estudio sobre la mortalidad de los trabajadores de producción de materiales de fricción, de particular interés ya que, aparte de dos breves períodos en que se utilizó la crocidolita, la única exposición es al crisotilo asbestiforme. Es necesario emprender estudios epidemiológicos en la industria del cemento de amianto y otros sectores, tales como los de fabricación de baldosas y productos de amianto y plástico. 477 ASBESTOS DISEASE IN MAINTENANCE WORKERS OF THE CHEMICAL INDUSTRY Ruth Lilis, and J. Sellkoff Environmental Sciences Laboratory, Department of Community Medicine, Mount Sinai School of Medicine of the City University of New York, USA Introduction Clinical field examinations of several large groups of workers in various plants of the chemical industry, undertaken by the Environmental Sciences Laboratory in the last years, have called our attention to the frequency of chest x-ray abnormalities (small irregular opacities and/or pleural changes) of the type known to be induced by dust exposure« Chest x-rays of workers of three vinyl chloride polymerization plants (1,2), a styrene polymerization plant (3), a titanium dioxide manufacturing (4) and a dye manufacturing plant were read without knowledge of age, past medical history, occupational history or findings on physical examination. Yet when parenchymal changes (irregular or rounded opacities) and/or pleural changes (thickening or calcification) were found, possible exposure to asbestos, silica or coal dust had usually occurred« It had been our practice when examining workers from chemical plants to make special efforts to include maintenance personnel, since it is well known that such work may often include significant overexposure to toxic substances, especially when repair becomes urgently necessary. In 1971 a report by Bittersohl and Ose had called attention to asbestos hazards in the chemical industry (5,6). 479 26 cases of mesothelioma had been observed over a period of 4 years (19671971)i this was in sharp contrast with the extreme rarity of this type of malignancy in the preceding periodi 22 patients had worked in a large chemical industry (Leuna), two in another chemical plant (Buna), one in a foundry. The only female patient, while not having had any occupational exposure to asbestos, was the wife of a worker at the Leuna plant. Only 16 patients had had direct occupational exposure to asbestos, while 9 had had indirect exposure (working in areas where asbestos was occasionally handled by other workers); in one case there only was a history of household exposure. Chest x-ray films preceding the development of mesothelioma were available in 23 cases i in 17 pleural thickening and pleural plaques were present. It was known that extensive insulation work had taken place in several departments of the Leuna chemical plant in the early 1950's. Large amounts of asbestos had been used and evidence for high concentrations of airborne fibers in the past was available. In these production areas and in adjacent shops asbestos exposure was subsequently a consideration for all workers, not only for those installing new insulation or removing old material. Maintenance work was thought to carry a special risk. Other sources of asbestos exposure, identified in the second chemical plant, were fire resistant protective equipment used by welders, and the manipulation of insulation with repair work on pipes. Population and Methods To obtain information concerning the potential dimensions 48o of asbestos hazards among workers of the chemical Industry, a eross-sectional Investigation of maintenance workers of a large chemical plant In New Jersey was undertaken. All were volunteers, and represented about half the men In maintenance categories In the plant (welders, carpenters, electricians, pipefitters, etc.). as many of those with terms We deliberately sought to Include of employment of more than 10 years as possible, and to examine only a sample of employees with shorter durations of exposure. Age distribution and duration since onset of exposure of the group are presented In Tables 1 and 2. 26% of those examined had less than 10 years and 59% had more than 20 years from onset of exposure. The examination protocol Included a lifetime occupational history, past medical history, smoking history, MRC respiratory questionnaire, complete physical examination, standard 14 by 17 Inch PA chest x-ray films and pulmonary function tests (spirometry and maximal expiratory flow volume curves). Chest x-ray films were read in consensus readings by four physicians experienced In occupational lung disease, without any knowledge of the past medical history, occupational history, respiratory symptoms or finding on physical examination, and categorized according to the ILO U/C Classification of Radiographs of Pneumoconioses. Results of pulmonary function tests - measure- ments of forced vital capacity (FVC), forced expiratory volume pen 1 second (FEV.) and forced expiratory flow over the mid FVC (FEF25-75^ were compared to the predicted values of Morris et al.(7), without knowledge of the occupational history, radiologic findings, 481 symptoms or findings on physical examination. Results Radiologic Findings Small irregular opacities, mostly in the lower lung fields, sometimes extending to the middle lung fields, of the type seen with parenchymal interstitial fibrosis, were present in 24% of those examined) in 11% this was the only abnormality (Table 3 ) . Pleural thickening and calcification (with or without thicken' ing) in 10% and 4% of cases respectively were found in the absence of definite radiologically evident parenchymal abnormalities) a total of 14% of those examined had pleural abnormalities only. In another 14% both parenchymal and pleural changes were seen. The overall prevalence of parenchymal and/or pleural abnormalities consistent with asbestos-induced changes was 33%. As expectedf the prevalence of all chest x-ray abnormalities was higher in workers with more than 20 years' exposure since onset of work (Table 4)) pleural changes were a more frequent abnormality in the group than were parenchymal. Careful analyses of life-long occupational histories recorded for all the 185 maintenance workers revealed that in 140 there had been no previous specific, defined occupational or nonoccupational dust exposure. In 45 workers, asbestos exposure ranging from minimal to significant, had occurred in the past, preceding employment in the chemical plant. Among those considered to have had significant previous exposure were workers who had been employed in an asbestos manu- 482 facturing plant, had been active as pipefitters or plpecoverers, had worked In brake maintenance and repair, or had participated in boiler repair work. These considered to have had minor previous exposure Included workers Involved In spackllng, shingle trimming, brake repair (minimal, Intermittent), and In one case, residence in the neighborhood (2 blocks) of an asbestos products manufacturing plant. A separate analysis was made of workers without any (even minimal) known preexisting asbestos exposure. When comparing the results with those obtained for the entire group of 185 workers, It was found that the prevalence of radiologic abnormalities, both parenchymal and pleural, was almost Identical (Table 5). The relationship between radiologic abnormalities and duration since onset of exposure (Table 6) was very similar In the group of 140 maintenance workers without any previous known asbestos exposure to that found In the total group of 185 examined workers (Tables 4 and 6)j there was no statistically significant differences in prevalence of parenchymal or pleural changes. Clinical Findings - Symptoms and Signs The only symptom reported with a higher frequency In workers with radiologic abnormalities was dyspnea on exertion (In those with both parenchymal and pleural changes) (Table 7). Cough and sputum production consistent with a diagnosis of chronic bronchitis (Table 8) were found In 20% of those examined. The differences In prevalence between current smokers and Individuals who had never smoked regularly was not significant (22% versus 14%). 483 (Exposure to dust and irritant fumes and gases in an industrial environment is often an underestimated etiologtc factor in chronic bronchitis) (Table 8 ) . Abnormalities on physical examination were infrequent) rales were present mostly in persons with pleural changes. Clubbing and rales were detected in several cases with negative chest x-rays, raising the question of parenchymal fibrosis not yet radiologically detectable. Results of Pulmonary Function Tests Pulmonary function tests (Table 9) indicated a relative low prevalence of restrictive disfunction (5% of cases), probably related to the small number of cases with advanced parenchymal fibrosis. An obstructive pattern was more often found, and was, as expected, more prevalent in current and ex-smokers. The finding of a lower than normal FEV./FVC ratio in 17% of maintenance workers with a negative smoking history again suggests that dust, irritant fumes and gases in an industrial environment may have an adverse effect on respiratory function.' Discussion While in this group of maintenance workers chest x-ray abnormalities were relatively frequent, pleural changes being more prevalent than parenchymal fibrosis, subjective symptoms and pulmonary function abnormalities were much less prominent. This constellation has been found to be rather characteristic 484 for relatively less Intense asbestos exposure. While progression to severe disabling parenchymal asbestosls Is less probable under such circumstancesf the risk for lung cancer and mesothelioma remains• The chemical plant maintenance workers examined had had various degrees of asbestos exposurei while some of them had experienced direct and continuous asbestos exposure for periods of time of more than 5 years, others had had direct, but intermittent, exposure for shorter periods of time. More than half of those examined had never been directly engaged In work with asbestosj nevertheless they had been present In areas where such work was performed by others (Table 11). A list of some of the job designations Included In this last category Is given In Table 12. The prevalence of radiologic changes was higher In workers with direct asbestos exposure. Nevertheless, It was considerable (25%) even In those with Indirect asbestos exposure. Comparative analysis of the entire group of 185 chemical plant maintenance workers and of the 140 subject without any previous asbestos exposure yielded interesting resultst prevalences of radiologic abnormalities (both parenchymal and pleural) were almost Identical. The relationship between prevalence of radiologic abnormalities and duration since onset of exposure was also very similar. These findings strongly suggest that asbes- tos exposure characteristic for maintenance work In chemical plants, Including Indirect ("bystander") exposure results In risks comparable to those documented for other types of as- bestos exposure, In other Industries and occupations. 485 The higher prevalences of radiologic pleural abnormalities (pleural fibrosis and/or calcification) than of parenchymal small irregular opacities (interstitial pulmonary fibrosis), the relatively low prevalence of restrictive ventilatory functional impairment and the paucity of clinical abnormalities all indicate that the risk for disabling asbestosis is less with this type of asbestos exposure. Nevertheless, the risk of lung cancer and mesothelioma is of concern, since accumulated experience indicates that low level asbestos exposure (indirect occupational, neighborhood or household exposure) is sufficient to result in a significant risk of developing mesothelioma (8,9,10). In the last several years, we have had occasion to observe a number of cases of mesothelioma in workers employed in chemical, oil refining, and petrochemical industries. It is possible that an increasing number of such cases may occur, since spectacular growth of these industries has taken place over the last 25 - 35 years, on the average, the critical latency period (11). 486 References 1. L i l i s , R., Anderson, H., e t a l . Prevalence of disease among v i n y l chloride and polyvinyl chloride workers. Ann. N.Y. Acad. S c i . 246 (1975). 2. L i l i s , R., Anderson, H., e t a l . Pulmonary changes among v i n y l c h l o ride polymerization workers. Chest 69(2):299-303 (1976). 3. lorimer, W.V., L i l i s , R., e t a l . C l i n i c a l s t u d i e s of styrene workers: i n i t i a l findings. Environ. Hlth. Perspectives 17:171-181 (1976). 4. Daum, S . , Anderson, H., e t a l . ' Pulmonary changes among titanium work e r s . Royal Society of Medicine, Sec. on Occup. Medicine 7 0 ( 1 ) : 31-32 (1977, Abstract). 5. B i t t e r s o h l , Von G. Epidemiologische Untersuchungen über Krebserkrankungen in der chemischen Industrie. Arch. Geschwulstforsch. 3 8 ( 3 - 4 ) ; 198-209 (1971). 6. B i t t e r s o h l , Von G., Ose, H. Zur Epidemiologie des Pleuramesothe liorna. Z. Gesamte Hyg. 17:861-864 (1971). 7. Morris, J . F . , Kolski, A., e t a l . Spirometrie Standards for healthy nonsmoking a d u l t s . Am. Rev. Respirât. D i s . 103:57-67 (1971). 8. Wagner, J . C . , Sleggs, C , e t a l . Diffuse pleural mesothelioma and a s b e s t o s exposure in the North Western Cape Province. B r i t . J. Indus. Med. 17:260-271 (1960). 9. Newhouse, M.L., and Thompson, H. Mesothelioma of pleura and peritoneum following exposure t o asbestos in the London area. B r i t . J . Indus. Med. 22:261-269 (1965). 10. Harries, P.G., Mackenzie, F . , e t a l . Radiological survey of men exposed t o asbestos i n naval dockyards. B r i t . J . Indus. Med. 29: 274-279 (1972). 11. S e l l k o f f , I . J . Cancer r i s k of asbestos exposure. In: Origins of Human Cancer. Ed. H.H. Hlatt, J . D . Watson, and J.A. Wlnsten, Cold Spring Harbor, N.Y., pp. 1765-1784, 1977. 487 Table 1 AGE DISTRIBUTION OF 185 MAINTENANCE WORKERS Age 20-29.9 30-39.9 40-49.9 50-59.9 No. * No^ No^ No^ 27 15% IS % 10% 34 % lfl% 488 85 % 47% 60+ No^ 21 % 11% Table 2 DURATION SINCE ONSET OF FIRST ASBESTOS EXPOSURE (YEARS) < 10 y r s . 10-19.9 years , 20-29.9 years 30+ y r s . Ho. % No. % No. % No. % 49 26% 27 15% 41 22% 68 37% 489 Table 3 Chest x-ray abnormalities consistent with asbestos-induced changes (parenchymal and pleural) i n maintenance workers - chemical plant (N=18S) Radiologic change (IIO UVC) None 0/0-0/1 . Parenchymal changes, t o t a l 1/0-1/2 2/1-2/3 3/2-3/4 Parenchymal changes only Pleural changes Pleural thickening only Pleural c a l c i f i c a t i o n (with or without thickening) A l l pleural changes 490 Number Percent 115 62% 45 42 3 0 22.4% 1.6% 20 11% 18 10% 7 51 4% 28% 24% - Table 4 Duration since onset of asbestos exposure and chest x-ray changes in maintenance workers (N=185) Radiologic changes Less than 20 years More than 20 years N = 77 N = 108 % Mo. % 66 86% 49 45% Parenchymal changes (total) 9 12% 36 33% 1/0 - 1/2 2/1 - 2/3 3/2 - 3/4 8 1 0 10% 1% 34 2 0 31% 2% Parenchymal changes only 8* 10% 11 10% Pleural thickening only 1 1% 17 16% 1% 6 6% 4% 48 .44% Ho. Normal (0/0-0/1) Pleural calcification 1 (with or without thickening, without parenchymal changes) All pleural changes 3 •See Table 6 . 491 Table 5 Chest x - r a y a b n o r m a l i t i e s c o n s i s t e n t with asbestos-induced changes (parenchymal and p l e u r a l ) i n maintenance workers - chemical plant - with no previous a s b e s t o s exposure (N=140) Radiologic change (ILO U/C) Number None 0/0-0/1 Parenchymal changes, t o t a l 1/0-1/2 2/1-2/3 3/2-3/4 Parenchymal changes only P l e u r a l changes P l e u r a l t h i c k e n i n g only P l e u r a l c a l c i f i c a t i o n (with or without thickening) A l l pleural changes 492 Percent 90 64% 34 31 3 0 24% 22% 2% 12 9% 14 10% 2 38 1% 27% - Table 6 Duration since onset of asbestos exposure and chest x-ray changes In maintenance workers with no previous asbestos exposure (N=140) Radiologic changes Less than 20 years More than 20 years N = 61 N = 79 Wo. Normal (0/0-0/1) 54 % Ho. % 89% 36 46% i Parenchymal changes (total) 6 10% 28 39% 1/0 - 1/2 2/1 - 2/3 3/2 - 3/4 9 1 0 8% 2% 26 2 0 33% 3% Parenchymal changes only 4* 7% 8 10% Pleural thickening only 1 2% 13 16% - 2 3% 5% 39 44% Pleural calcification 0 (with or without thickening, without parenchymal changes) All pleural changea 3 •Parenchymal changes (only) was the only radiologic abnormality with significantly higher prevalence In workers with previous asbestos exposure (X =4.63; p<0.03). *93 Table 7 Symptoms . Prevalence of respiratory symptoms In maintenance workers (N=185) Abnormal chest x-ray Parenchymal Normal Parenchymal Pleural and chest x-ray only only pleural («=118) » (N=20) (N=22) (M=25) ÏÏ2i * — ïï£l Ï — Ü2¿ % — No. % — 4 18% 11 44% 6 27% 7 28% 32% 6 24% Shortness of breath 19 16% 2 10% Wheezing 27 23% S 25% Chronic bronchitis 20 17% 3 15% 7 494 Table 8 Prevalence of chronic bronchitis In maintenance workers - chemical plant Sknoklng habits Total number examined Chronic bronchitis (MRC) Ho. % 67 IS 22% Ex-smoker 75 15 20% Never . smoked 42 Total 184 Present smoker 14% 36 495 20% Table 9 Objective changes on physical examination In 185 maintenance workers Chest x-ray Abnormalities on physical examination Normal chest x-ray (N=118) No. X Clubbing 7 6% findings Abnormal che St X -ray Both parenchymal Parenchymal Pleural changes changes and pleural only changes only (N=20) (N=22) (N=25) No. 0 X - No. No. X 1 X SX 1 4X 3 14X 3 12% 1 5X 1 4% Rales 8 7X 0 Cyanosis 1 1% 0 - Increased AP diameter 4 3% 0 _ 1 SX 5 20% Decreased breath sounds 6 SX 1 5X 0 - 4 16% Decreased heart sounds 3 3% 2 10X 2 9X 1 4% Wheezing and/or rhonchl 7 6% 1 5% 2 9X 1 4% 5X 3 14% P II > A II 5% 4% 8X «R •o »«I ol o ¡El •"• ««i S ál N os in A S2 ; il Ü I h a d a M o •H •H a > a 3 00 O « rt CD bS ISTI «* o s*l I S I a N •H O •» +* Q ° M Q) « &4 •» a "»^ o o vt ME •» O) O f- ». V I n U S I a u is O H H +> >> e o e o > «in II •» s o a V «H t« » Svi VI 3 S .o à. i o T Il B s a h O +» -H n +» J> u O Q 3 •H VI a n S' 497 4» ( S U i-l fi •» O (9 • * •S • * o n a ST. <H •o 3 c I & ^ a g o o > a £1 <s a Ì a SS 1 ? Îï •» u s* *«l S m a a a o a a I! o 9 *t o Table 11 CHEST X-RAY ABNORMALITIES IN CHEMICAL PLANT MAINTENANCE WORKERS Abnormal c h e a t x-ray Number Number % 41 20 49% Intermittent, l e s s than S years) 36 17 47% Never direct asbestos exposure ("bystander") 108 27 25% Direct asbestos . e x p o s u r e (more t h a n 5 years) Direct asbestos exposure ("minor" - 498 Table 12 MAINTENANCE WORKERS - OCCUPATIONS WITHOUT DIRECT HANDLING OF ASBESTOS Laborer Stock man Area mechanic Sheet metal mechanic Mechanic helper Maintenance helper Millwright Repair man Pipefitter Production worker 499" BIOLOGICAL EFFECTS OF ASBESTOS - THE UNRESOLVED MATTERS S. F. McCULLAGH James Hardie & Coy. Pty. Limited, Granville, N.S.W., Australia We all recognise the serpentine asbestos chrysotlle and the amphiboles crocldollte, amoslte, anthophylllte, tremollte and actlnollte. However, the US National Institute for Occupational Safety and Health (NIOSH) In 1972 defined asbestos as any substance which under phase contrast microscopy at about 500 x, has a length greater than 3 times Its diameter, a length >5jm and a width <3yum. This definition, now given the force of law In the US by the Occupational Safety and Health Administration (OSHA) includes fibres which are not minerals and also minerals which are not fibres» Great semantic confusion will result If we refer to these other substances as asbestos or even as "asbestos" or as "asbestlform fibres"« These other substances may be most precisely referred to collectively as OSHAsbestos. I am not trying to be funny. I commend this term to youi for some such term we must have If confusion Is to be avoided. Hard rock gold miners in Lead, South Dakota, have been exposed to an amphibole OSHAsbestos and have been reported to show an excess of lung cancer by Gillam et al. (1976), but McDonald et al. (1978). In a much more extensive study and In one much better designed to detect an excess If It Is there, found none. This OSHAsbestos Is harmless. 5o1 Barts (1978),. on the other hand, has described two small foci of endemic mesothelioma in Turkey believed to be due to the fibrous aluminium silicate erionite - this OSHAsbestos is dangerous. Much work needs to be done to determine the biological effects of the substances in the OSHAsbestos categoryi these studies will have to be of immaculate design. The confusion, misunderstanding and, sometimes, bitterness which has characterised the debate over the S substances that are asbestos has been much contributed to by poor experimental design and unjustified inference! the consequences of permitting the same thing to happen vis à vis the innumerable substances that are OSHAsbestos are frankly too horrible to contemplate. What Constitutes an Asbestos Exposure? What constitutes an asbestos exposure? It has long been held that, generally, some 10 to 15% of mesotheltomata are not attributable to asbestos exposure (Wagner et al., 1971), but the most recent, and probably the most soundly based, estimate puts the figure at 33% (McDonald & McDonald, 1977). The figure varies astonishingly widely from 5% in Scotland (McEwan et al., 1970) to 80% in Italy (Rubino et al., 1972). A comparison of the case-control studies of McEwan et al., (1970) in Scotland and of McDonald et al., (1971) in Canada shows that a history of asbestos exposure is likely to be elicited twice as commonly in Scotland as in Canada, and this applies equally to cases and controls. It may be as McDonald (1977) argues that such differences are reali "areas with high exposure rates in controls are characterised both by the presence of dockyards and a high 5o2 high Incidence of mesothelioma! whereas areas with'low rates .... have neither". However, we will not know whether such differences are real or whether they are due to differences In the definition of what constitutes an asbestos exposure unless we reach agreement on what, In fact, constitutes an asbestos exposure. This will not be easy but is needs to be done. Morphology and Mesothelioma. The relative potency of different types of asbestos as causes of mesothelioma has been the subject of much debate, but the data have recently been summarised by McDonald (1977) and can leave us in little doubt that the great majority of cases are due to the fine-fibred crocidolites, some to amosite, a few to chrysotile and none to anthophyllite. Studies of the morpho- logy of these fibres have led to the conclusion that they are most potent when they are durable in vivo, rod-like in shape (not curly like chrysotile) and of diameter ¿-1.0pm and length >10.^ura (Timbrell, 1973t Wagner et al., 1973| Stanton et al., 1977). It Is hypothesised that the curly fibres of chrysotile are deposited proximally while amphibole deposition is preferentially peripheral as fibre diameter decreases, and thus it is that the fine crocidolites predominantly reach the pleura and cause mesothelioma - though how then are we to explain the benign pleural lesions so commonly associated with anthophyllite? The hypothesis Is further challenged by reports from France that electron microscopy has revealed that it is amphibole asbestos 5o3 that is predominantly found in pulmonary tissue itself while in the pleura it is chrysotile that one most commonly sees (Le Bouffant, 1974| Desbordes et al., 1974| Le Bouffant et al., 1976)i though one must observe that the number of cases that have been studied and reported is small and, as Desbordes and his colleagues have observed, the matter "mérite d'être confirmée par de plus nombreauses observations." Selikoff et al., (1973) reported 7 cases of mesothelioma occurring between 1941 and 1971 among 877 men first employed in the manufacture of insulation material containing only amosite asbestos between 1941 and 1945; seven is not a large number of cases, but the incidence about 0.26/1000/year is higher than the South African described by Webster (1973) would have led one to observation is the main stumbling block to the logical carcinogenesis, so largely based on of experience expect. This theory of morpho- the work of Timbrell, which I have already outlined. Selikoffs 877 men worked in a factory in Paterson, New Jersey, and there seems little doubt that their work there exposed them only to amosite asbestos. I Hovfever, a patient search of the monthly trade journal Asbestos shows that crocidolite, most of it South African, though also some Australian and some Bolivian, was for some years commonly milled in the New Jersey. State of Milling of crocidolite, and other types of asbestos, appears to have commenced in 1921 at Bound Brook, in NJ, to have transferred to larger premises in Millington, NJ, in 1928 and to have continued there until the end of 1946 when another Company began similar operations in Jersey City, NJ. 5o4 How many of the men employed in this Paterson Plant between 1941 and 1945, who are subjects of Selikoff's study, had previously been exposed to crocidolite at Bound Brook or at Millington, we simply do not know and whether the 7 mesothelioma were due to amosite or crocidolite we cannot say. The Company that operated the Paterson Plant conducted similar operations at Cicero, 111., and at Blue Island, 111. In retrospect it seems likely that these two Illinois workforces would have provided more satisfactory data. Asbestosls and Lung Cancer The International Labour Office, in 1972, stated that lung cancer in asbestos workers "occur, so far as is known, only in workers whose lungs show signs of pneumoconiosis"! the ILO, as usual, felt sufficient in its own authority and gave no indication of the basis on which its statement was foundedt presumably it rests upon the work of Doll (1955). Martischnig et al., (1977) reported that of 201 men with bronchogenic carcinoma, who were not regarded as "asbestos workers", a history of asbestos exposure could be significantly more frequently elicited than from 201 controls. They stated that none of their cases had asbestosis but unfortunately do not set forth the evidence on which this opinion was based) we have, therefore, no more than their obiter dictum. Were Martischnig and his colleagues correct one would expect ferruginous bodies to be found more commonly in the lungs of people with bronchogenic carcinoma than in controls i it has been re- 5o5 ported that this is so by Warnock and Chrug (1975), but more commonly reported that tt is not so by Elmes & Wade (1965), by Doniach et al. (1975) and by Whitwell et al. (1977). The limited evidence of Fletcher (1972) remains the best we have - 16 of 408 shipyard workers died of bronchogenic carcinoma (cf. 6.74 expected)« none had radiological evidence of pulmonary who came to necropsy, only one had slight asbestosis and, of 5 histological evidence of this disease. A study of this same group of workers suggests that pleural plaques are associated with an increased risk of bronchogenic carcinoma but the findings are, as yet, inconclusive as Edge reported in New York earlier this year (Edge, 1978). On the other hand, Kaski et al (1968), in Finland, in a case-control study of 279 pairs reported no excess of attributable to the presence of pleural bronchogenic carcinoma plaques, whether calci- fied or not. The Arc of Endemic Pleural Pathology There is accumulating evidence of a great arc of pleural pathology swinging through Central Europe' from Finland In the north (Kiviluoto, 1965 and 1978), through the USSR (Ginzberg et al., 1970), the GDR (Anspach, 1962), Czechoslovakia (Rous and Studeny, 1970» Navratil, 1970), Bulgaria (Burilkov and Michailova, 1970), down to Turkey in the South (Yazicioglu, 19761 Yazicioglu, et al., 1978, Baris et al., 1978» Baris, 1978). These are a most interesting series of endemics. We need further radiolo- 5o6 gical surveys to discover others i we need to determine the airborne fibre thought responsible and Its morphology and concentration! and we need to determine whether or not there Is associated morbidity or mortality. In the case of Turkey It Is believed that the OSHAsbestos erlonlte Is responsible for two small foci of endemic mesothelioma south of Ankara (Baris, 19781 Baris et al., 1978)j endemic pleural calcification occurs at and about Dlyarblklr, south east of Ankara, perhaps due to Chrysotile, the evidence of associated disease Is somewhat confused (Yazlcloglu, 19761 Yazlcloglu et al., 1978)i In another endemic to the north of Ankara pleural plaques occur but mesothelioma has not been found (Baris, 1978). On the other hand, at the north of this great arc, In Finland, repeated studies have failed to find any excess of bronchogenic carcinoma associated with the endemic pleural disease (Ktvlluoto, 1965| Kaskl et al., 1968» Klvlluoto, 1978) despite the fact that excessive exposure to the asbestos concerned, anthophylllte, has been shown to be associated with an Increased risk of bronchogenic carcinoma (Meurman et al., 1974). This Is a most Important observation since It strongly suggests that there Is a level of exposure to this which does not elicit the expected known human carcinogen carcinogenic response. In other words, there is a safe dose - we just need to know what It Is. 5o7 References. Anspach M. (1962), Int. Arch. Gewerbepath, 1£), 108. Baris Y.I. (1978), Ann. NY Acad Sci, (in press). Baris Y.I. et al., (1978), Thorax, 3¿, 181-192. Burilkov, T. & Michailova L. (1970), Environm Res, ¿Î, 443-451. Desbordes J. et al., (1974), Lyon Méditerranée Médical, X, 157-162. Doll R. (1955), Brit. J. industr. Med, 1¿, 81-86. Doniach I. et al., (1975), Brit. J. industr. Med, 3£, 16-30. Edge J.R. (1978), Ann. NY Acad. Sci, (in press). Elmes P.C. & Wade O.L. (1965), Ann NY Acad Sci, 13J2, 549-557. Fletcher D.E. (1972), Brit. J. industr. Med, 29, 142-145. Gillam J.D. et al., (1976), Ann. NY'Acad. Sci,, 271, 336-344. Ginzberg E.A. et al., (1970), Kliniceskaya Med, lj2, 55-56. International Labour Office (Report on the Meeting of Experts on Control and Prevention of Occupational Cancar, Geneva, 10-17 Jan. 72, p. 6, para. 24. Kaski P. et al., (1968), Proc. Internat. Konf. biolog. Wirkungen des Asbestes, Dresden, pp. 274-275 (pubi. 1973). Kiviluoto R. (1965), Ann. NY Acad. Sei, 132, 235-239. Kiviluoto R. (1978), Ann. NY Acad. Sci, (in press). Le Bouffant L. (1974), Environm. Hlth. Perspectives, 9, 149-153. Le Bouffant L. et al., (1976), Revue Française des Maladies Respiratoires, 4, (suppl. 2 ) , 121-140. Martischnig K.M. et al., (1977), Brit. Med. J, i., 746-749. McDonald J.C. (1977), Proc. Symp. Asbestos, Johannesburg, 67-78. McDonald J.C. Û McDonald A.D. (1977), Prev. Med, 6, 426-446. McDonald J.C. et al., (1971), Arch. Environm. Hlth, 22, 677-686. McDonald J.C. et al., (1978), Amer. Rev. resp. Dis. (in press). McEwan J. et al., (1970), Brit. Med. J, iv, 575-578. Meurman L. et al., (1974), Brit. J. industr. Med, 31, 104-112. Navratil M. (1970), Proc. Internat. Symp. Brit. Occup. Hyg. S o c , London, Vol. 2, 695-703. Rous V. & Studeny J. (1970), Thorax, 25, 270-284. Rubino C F . et al., (1972), Brit. J. industr. Med, 29, 436-442. Selkoff I.J. et al., (1973), Revue Française des Maladies Respiratoires, 4, (suppl. 2 ) , 121-140. Stanton M.F. et al., (1977), J. Nat. Cancer Inst., 58, 587-603. Timbrell V. (1973), Biologie Effects of Asbestos, IARC Scientific, Publication No. 8, p.p. 295-303. U.S. Occupational Safety and Health Administration, 1972, Fed. Reg., T7> (11a), 11318-113322. Wagner J.C. et al., (1971), 3ric . M.îd. lull. 27, 71-76. Wagner J. C. et al., (1973), Brit. J. Cancer, 28, 173-185. Warnock M.L. and Churg A.M. (1975), Cancer, 35, 1236-1242. Webster I. (1973), Sth.Afr. Med. J., 47. 165-171. Whitwell F. et al., (1977), Thorax, 3_2, 377-386. Yazicioglu S. (1976), Chest, 70, 43-47. Yazicioglu S. et al., (1978), Chest 73, 52-56. 5o9 Efectos biologicos del amianto: problemas pendientes. S. F. McCullagh (Australia) ¿Qué es el amianto? Es necesario definirlo, porque la definición efectuada por la O.S.H.A., que tiene fuerza de ley en Estados Unidos, incluye muchas substancias que no son amianto en el sentido en que se entiende comúnmente la palabrai los efectos biológicos de estos otros materiales han sido poco estudiados, pese a que uno ha demostrado su nocividad y otro es mortal. ¿Que es la exposición al amianto? La proporción de mesotelioma que puede ser atribuible a la exposición al amianto va de 20 por ciento en Italia a 95 por ciento en Escocia. Estas diferencias pueden ser reales, pero habría que definir lo que se considera como exposición al amianto para resolver la cuestión. ¿Qué tipos de amianto y de qué morfología son los más peligrosos? ¿Es posible escoger entre las opiniones de Timbrell y sus colaboradores en el Reino Unido y las de Bouffant y los suyos en Francia y las de Selikoff y los suyos en Estados Unidos? ¿El carcinoma broncógeno atribuible a la exposición al amianto se produce únicamente en presencia de asbestosis pulmonar o pleural o también puede presentarse en ausencia de estas dolencias? La incidencia de mesotelioma en trabajadores antes ocupados en Patterson, Nueba Jersey, en la fabricación de materiales aislantes que sólo contenían amosita ha sido mayor de lo que se podía esperar en base a la experiencia sudafricana. ¿Pero hasta qué punto han estado expuestos anteriormente en Nueva Jersey a la crocidolita? Parece existir un amplio arco de patología pleural que a través de Europa Central pasa por Finlandia, República Democrática Alemana, URSS, Checoslovaquia, Bulgaria y Turquía, y que afecta a personas que no se encuentran expuestas por razones profesionales, ni para-profesionales, ni de vecindad, al amianto. Tenemos que determinar qué fibras son responsables, cuáles son las concentraciones en el aire y si existe morbilidad o mortalidad asociada a las mismas. 51o BIOLOGICAL EFFECTS OF ASBESTOS-QUARTZ DUST-MIXTURES W. Weiler Pneumoconiosis Research Institute, Bochum, Federal Republic of Germany Introduction This experiment was carried out to study the combined effect of chrysotile-quartz and crocidolite-quartz mixtures. The investigation of combined effects is also of great practical importance'. For instance, asbestos cement as well as talc con- tain asbestos and quartz. The intraperitoneal test applied is a well examined method, not only for quartz dust injections, but also for asbestos dust administration (Pott et al., 1976; Weller, 1977). On the whole this was a relative long-term experiment lasting 6 months. This period is certainly sufficient for the recognition of fibrogenic properties, but generally insufficient for the discovery of careinogenity. On the other hand the method applied in our tests permits the early recognition of modifications. While evaluating the tests special attention was paid to the determination of quantitative parameters. Methodology Tests were performed with a total of 197 female SPFSprague-Dawley rats. Table 1 shows detailed data on test groups, kind and quantity of the injected dust and also the number of animals in each group. At the beginning of the tests animals were 12 months old. 511 Name of the qroup Group Treatment Asbestos Quartz (mq) (mq) - - 5 5 6 - 5 5 5 6 7 7 - 5 5 S 7 7 6 5 10 15 •* 5 5 5 7 5 7 15 10 5 15 10 5 - 5 5 5 7 7 7 5 5 5 7 7 6 Con crol 1 Chrysotile ï a b c 3 a b c 5 10 15 - 5 10 15 - Quartz 4 a b c - Chrysotile + Quartz S a b c 5 10 15 Crocidolite + Quartz 6 a b c 5 10 15 Crocidolite Number of examined anijials o months 3 months 6 months - Table 1: Test scheine. The applied asbestos dust was UICC standard dust crocidolite and chrysotile B, the quartz dust was Dörentrup quartz No. 120. The dust was suspended in physiological NaCl solution without adjuvant. 1 ml. Each animal received an intraperitoneal injection of After test periods of 3 and 6 months a part of the animals was etherised and sacrificed. After body-weight determination the following organs were removed and weighed! liver, lien, omentum, lung lymph nodes, cranial and caudal mesenteric lymph nodes. According to the findings modifications outside the omentum, ovaries and peritoneal liquid were removed. From the removed material histological sections and smears were taken. Results a) Animal and organ weights The animal weights did not show any dependence on dust type and dose. exposure were The organs that might show reactions on dust omentum, liver and lien. Because of the small dust quantities and very high organ weights only slight modifications had been expected. Only quartz groups showed a corre- lation between organ weights and dust dose. We did not find 512 a direct dependence on dust type and dust dose tn the other groups. Table 2 summarises the weights of different lymph node groups. According to the manifold experience with quartz dust and coalquartz mixtures in intraperitoneal tests the lung lymph node and cranial mesenteric lymph node' weights were added up to obtain the total lymph node weight. Injection Asbestos Quartz Group (ITO) Control 1 Chrysotile 2a 2b 2c 5 10 15 Crocidolite 3a 3b 3c 5 10 15 Quartz 4a 4b 4c Chrysotil« • Quartz Sa 5b 5c 6a 6b 6c Crocidolite + Quartz (TO) Lung Lynch notfes 3 Hon. 6 Hon. 21 i e 27 î 4 24 Ï 6 29 Î 11 26 * 6 5 10 15 5 10 15 15 10 5 5 10 15 15 10 5 28 | 7 n 19 Crani! iresentfi] lynph nrie 3 Man. jdes 6 Mon. 33 î 4 35 î 9 a 42 î 7 42 î 6 39-7 31-8 34-; 8 35 î 7 5 5 Î 1 7 S3 I 11 50 I 13 53 i e 53 - 22 54 - 11 6 2 - 8 78 - 15 1 0 8 - 2 6 63 - 13 129 î 24 134 ; 29 104 ï 20 164 - 24 186 - 42 131 - 30 66 52 48 164 144 101 ; Í î Ï - 16 7 10 32 38 22 96 î 2S 68 J 11 69 ; 28 55 i 10 52 - 10 38-6 Total lynph nodes 3 Mon. 6 Mon. 54 î 7 62 - 13 Cauda] mesenteric lynph nodes 3 Mon. 6 Mon. 28-8 34 t , 26 î 5 27 î 5 34 î 8 32 i B 37 í 9 80 j 17 141 j 20 188 j 31 27 1 4 110. j 29 233 î 43 244 ; 57 48 I 15 155 - 45 295 - 52 341 - 81 37 í 5 97 Í 22 134 j 26 193 | 43 32 2 12 74 ï 13 107 î 14 143 j 35 3 0 Î 7 62 - 11 100 - 6 100 - 13 29 - 3 36 j 10 66 j 11 71 I 16 39 î 7 65 - 12 38 î 8 89 j 23 56 j 8 49 î 15 106 I 10 63 - 19 115 - 24 64 68 69 91 99 117 j j ; I - 12 13 10 9 25 25 33 î 9 23 î 4 26 I U 26-6 35 2 16 32 í 8 30 î 7 36 37 33 42 40 36 î j i î 2 î 9 12 6 10 14 7 166 Í 33 132 j 41 142 î 47 296 ; 48 308 j 43 43 j 13 41 I 11 126 j 31 113 - 21 121 J 37 257 I 57 247 j 53 46 2 9 53 j 12 108 - 38 93 - 25 110 - 17 194 - 34 218 - 48 32 î 7 47 î 10 Table 2: Organ weights of lymph nodes correlated to test period (total lymph nodes = lung lymph nodes and cranial mesenteric lymph nodes). Mean values with single standard deviation. Rats, intraperitoneal test. With the exception of the caudal mesenteric lymph nodes the other lymph node weights show direct, dose-dependent relations. The following graph, including a better survey on lymph node. weights than the table, is based on results obtained after a three months' test period (fig. 1). 513 Total lymph nodes ( mg ) -Quartz • Crocidolite -Quartz 300 -, 200 o—Quartz« Chrysotile —Crocidolite 100- -Chrysotile -Control Dust types : 5 Dust mixtures: »15 Fig. 1: 10 >10 15 • 5 mg Quartz and Asbestos r e s p . mg Asbestos Total lymph node weight after a 3 months' test period dependent on dust dose (total lymph node weight = weight of lung lymph nodes and cranial mesenteric lymph nodes). Quartz shows the typical dose-dependent increase of the total lymph node weight. It is obvious that crocidolite has an essen- tially greater quantitative effect than chrysotile. Asbestosquartz mixtures yielded surprising results. The quantitative quartz effect is decreased, dependent on the dose, by addition of chrysotile. However, an addition of crocidolite causes, also dependent on the dose, an increase of the quantitative quartz effect. 514 This interesting reaction is investigated in more detail in table 3 by organ weight increases (= net weights, i.e. actual organ weight minus organ weight of control group). Increase of organ weights (üi mg) Total lymph nodes (lung lymph nodes + cranial mesenteric lymph nodes) Dust Chrysotile 3 Ntin. 6 Mon. Crotitiolite 3 Mon. ó ton. 5 mg Asbestos 15 trq Quartz 12 241 2 279 35 241 29 279 Set v a l u e : Total of dust types Actual v a l u e : Dust mixture {5 mq a s b e s t o s + 15 mq quartz) 253 80 281 131 276 242 308 246 % Actual value of s e t value 32% 474 88% 80% 10 mg a s b e s t o s 10 mq quartz 17 179 6 182 52 179 37 182 Set v a l u e : Total of dust types Actual v a l u e : Dust mixture (10 mq a s b e s t o s + 10 mq quartz) 196 53 188 81 231 203 219 185 % Actual value of s e t value 27% 43% 15 mg a s b e s t o s 5 mq quartz 11 87 7 126 61 87 55 126 S e t v a l u e : Total of dust types Actual v a l u e : Dust mixture (15 mq a s b e s t o s + 5 mq quartz) 98 46 133 38 147 140 181 156 % Actual value o f s e t value 47% 29» 88% 95% 84% 86% Table 3: Presentation of organ weight modifications caused by the particular dust types and dust mixtures. The net weight determined after injection of the particular dust type serves as reference value. The actual value is the deter- mined net weight of the identical dust mixture. When using chrysotile all examined mixture ratios show a substantial de- crease of the quartz reaction both after 3 months and after a 6 months' test period. After a 3 months' test period the determined value of a dust mixture has on the average only 357. of the expected effect provided that the particular dust types have an additional effect. After a 6 months' test period the value 515 months to 43% due to a progressive development after a pure quartz Injection. When using crocidolite, however, on an average 90% of the expected quantitative tained after a 3 months' test period. reaction were ob- Particularly mixtures containing a high proportion of asbestos show an almost addi- tional reaction effect of both dust types. Regarding the quantitative progression of modifications the following observations could be made; corresponding to the known typical reaction the organ net weights increase after quartz injections from the 3r to the 6 test month. Thus, the maximum quantitative re- actions might be obtained for the applied doses (Weiler, 1977). The quantitative progression of asbestos is shown in figure 2. Total lymph nodes Increase of organ weights rng 80 i 60- o* ,.<r 40- 3 Mon. 6 Mon'— Crocidolite -•or"' 20 0 i££ - 3 Mon. •6 Mon."—I Chrysotile -1— 10 15 mg Asbestos Fig. 2: Presentation of the net weight increase of the total lymph node weight due to asbestos dust dependent on test period and dust dose. 516 These values indicate that in each dosage both chrysotile and crocidolite do not react progressively, but regressively. Besides, the different quantitative effect of the two asbestos dust types is obvious again, showing in addition a relation depending on the dose. In summing up it can be said that the weight of the lung lymph nodes and cranial mesenteric lymph nodes and especially the total lymph node weight obtained by adding the two values show unequivocal interpretable relations. a substantially Crocidolite provokes greater reaction than chrysotile. Mixed with quartz, chrysotile has an inhibitory effect, whereas crocidolite almost causes a synergism of the effect of the components quartz and asbestos. b) Macroscopic pathology The macroscopically visible modifications on opening the peritoneal cavity after a 3 months' test period, will be presented first. After an injection of 5 mg chrysotile the omentum only shows bright spots. With greater dosages there are, in addition to the omentum small deposits on the peritoneum and on the liver. Similar grey-green deposits can be found in the cro- cidolite group. These deposits are flat and streaky rather than defined granulomes. With lower dosages conglutinations of omentum, liver and diaphragm also occur. Higher dosages result in additional conglutinations of the lien. The lymph nodes of both groups do not present consistency modifications. 517 In the quartz group the typical solid white nodules can be found on the omentum as well as outside the omentum. the The higher quartz quantity the bigger and the more solid are the lymph nodes• The typical quartz effect is completely converted in the chrysotile-quartz mixture group. A mixture of 15 mg quartz and 5 mg chrysotile causes soft granulomas compared to the solid ones obtained after an injection containing 15 mg pure quartz. The appearance of the of the typical lymph nodes is almost normal; a great reduction quartz effect can be observed. There is a distinct quartz effect in the crocidolite-quartz group. The granulomas due to the crocidolite proportion show a slight grey-green colorationi besides, there are conglutinations of omentum, liver, lien and diaphragm. The lymph nodes are solid, and their colour is white-grey. After a test period of 6 months the macroscopic changes are about the same. Compared to the findings after 3 months, the granulomas and lymph nodes in the chrysotile-quartz mixture group are of a more solid consistency, i.e. the quartz effect is a little more distinct. • c) Special pathological modifications After a test period of 3 months as well as after 6 months the appearance of ascites, ovarian cysts and tumors was macroscopi- cally observed. Table 4 includes a summary of these findings. 518 Ndme of the qroup Control Chrysotile Crocidolite Quarts Chrysotils + quarts crocldoUt» + quarts Group 1 2 a b c 3a b c 4 a b c Sa b c 6 a b c N 5 5 5 5 5 5 5 5 5 5 5 S 5 5 5 5 3 months' test period Ascites O/arian- Tutor N cvst 6 1 6 1 5 - 2 3 5 6 months' test period Ascites Ovarian- Tumor cvst 1 1 1 3 4 4 2 6 5 1 - 1 - 5 5 1 J 4 4 - 4 1 2 5 1 1 1 1 6 1 1 1 1 Table 4: Frequency of special pathological findings in the individual test groups. Ascites only occur in the crocidolite group, the frequency of which increases with the test duration. There seems to be a certain dependence on the dose. Smears were taken and coloured according to Papanicolau, and partly a HE-coloration was made. Cytologic findings did not indicate tumor growth; crocidolite fibres could not be found either. The animals of each group showed ovarian cysts. However, compared to other test groups their frequency is much higher in the crocidolite groups. d.) Histology The presentation of the results obtained by a histological study mainly comprises data after a test period of 6 months. The chrysotile group, the group with the lowest dose, shows a slight cellular infiltration of single omentum ansea with a fibrosis degree of I/II up to I1/II1 (King). The group with the highest dosage shows, in addition, to these infiltrations, single and rather small granulomas with numerous cells and a fibrosis degree of II/III. are found. Outside the omentum granuloma-shaped deposits Liver, lien and the 519 different lymph nodes did not show any particularities compared to the control group. Even the smallest dosage in the crocidolite group causes granu= lomas in and outside the omentum with fibrosis degree III. Especially the granulomas outside the omentum present outstanding polynuclear giant cells (Langhans-type). Granulomas in the group with the highest dosage are partly hyaline in the centre. For the first time this group presents numerous asbestos fibres at irregular distances, coated by oval deposits of different sizes. They are likely to be the so-called asbestos bodies or "ferruginous bodies". Liver and lien do not show modifications. Regarding the lymph nodes, the most distinct modifications could be seen in the lung lymph nodes. They are similar to typical quartz-caused lymph nodes (foci with a diameter of almost lOÇum containing a large number of fibres). There is no evidence of fucos-related fibrosis. The group with pure quartz injections shows the usual, frequently discussed modifications (Weiler, 1977). The test groups treated with chrysotile-quartz mixtures present quartz-typical modifications in and outside the omentum. Only in the group treated with a mixture of 15mg chrysotile the cellular infiltrations of omentum ansae typical for this asbestos type are present. However, the quartz-typical modifications in liver and lien are scarcely found even in case of a high quartz proportion. The lymph nodes, too, show fewer quartz-typical foci,, and frequently the absence of a confluence tendency can be observed. In the group treated by crocidolite-quartz injections the 52o modifications in and outside the omentum were due to the quartz proportion. Large numbers of crocidolite fibres can be found. The polynuclear giant cells typical for crocidolite asbestos can be found only in the modifications of the group with the highest asbestos proportion. quartz-typical in the group The number and extention of the foci in liver and lien are more similar to those with pure quartz injections. In the lymph nodes the reaction seems to be more distinct than in the corresponding quartz groups. Even if the quartz proportion is small, confluent quartz-typical foci are present. The crocidolite fibres are numerous! they exclusively occur in quartz-typical areas. e) Discussion The different reaction of chrysotile as compared to that of crocidolite may have the following causes: influence of fibre length, higher natural quartz content in crocidolite and application of a new evaluation method. According to Robock (1974) there are no differences between the asbestos dust types used regarding fibre length distribution ranging from 0,2pjm up to 20Qum. Therefore, it is more likely that a potentially present natural quartz proportion and mainly, the evaluation method based on the total lymph node weight, so far not used in asbestos studies, are important factors. Besides, there was a close relation between quantitative evaluations and pathological findings in our tests. The carcinogenic properties, not examined in this study, are much more important that the fibrogenic effect of different asbestos types. With great probability, the observed subcutaneous tumors do not correlate to asbestos injections. 521 Histologically, they are fibro-adenomas. Hemorrhagic ascites of experimental animals after asbestos injections were described only by Pott et al., (1976). It has not yet been defined whether they are due to a mechanical effect only or whether they should be seen in connection with carcinogenic characteristics. The same can be said about the numerous appearances of ovarian cysts that have not yet been described. It is interesting that both modifications can be ob- served mainly after crocidolite gated in future injections. It should be investi- studies to which extent conclusions can be drawn from the described different effects of chrysotile and crocidolite, both isolated and in combination with quartz, regarding the different carcinogenic effects of the two asbestos types. 522 References King, li..J . , <J. Nage) uchmi ÜL Die pathologische Wirkung verschiedener Minoici I üLüube im Tierversuch In: Die Staublungenerkrankungen '¿, 84-95, Darmstadt, 1954 l'ott, b". , K.ll. Friedrichs, F. Iluth lirgebnisso aus Tierversuchen zur kanzerogenen Wirkung faserförmiger Stäube und ihre Deutung im Hinblick auf die Tumorentstehuni) beim Menschen Zbl. Bakt. Hyg. I., Abt. Orig. 13. lj>2, 467-505 (1976) Koboek, K. Die Wirkung mechanischer, thermischer und chemischer Behandlungen von Siliciumdioxyd- und AsbestStäuben auf Zytotoxizität und Elektronenstruktur Beiti-, SiLikose-Forschung 26, , 1112f>> (1974) Wullor, W. Anthrakosilikose Bergbau-Uerufsgenossenschaft, Bochum, 1977 Address: Priv.-Doz. Dr. W. Weller Silicosis Research Institute Hunscheidtstrasse 12 D-4630 Boahum Fed. Rep. Germany 523 Efectos biológicos de las mezclas de polvo de amianto v cuarzo. W. Weiler (República Federal de Alemania) ha investigación de los efectos combinados de la exposición al amianto y al cuarzo es de gran Interés práctico, por lo cual se estudiaron los efectos del crisolito B y de la crocidolita, así como de las mezclas de polvo de cuarzo y amianto, en pruebas intraperitoneales con ratas, de hasta seis meses de duración. Además, en este experimento de corta duración, se examinaron la eficacia de un nuevo parámetro cuantitativo y los métodos de diagnostico de las alteraciones tumorígenas precoces en la evaluación de los efectos del polvo. Se obtuvieron los siguientes resultados i el peso de los nodulos linfáticos del pulmón, de los nodulos linfáticos del mesenterio craneano y el peso de la mayoría de todos los nodulos linfáticos obtenido por adición de ambos valores muestran una relación inequívoca con la inhalación de polvo. La crocidolita provoca una reacción cuantitativa considerablemente mayor que el crisotilo. Mezclado con cuarzo, el crisotilo tiene un efecto inhibitorio, mientras que puede observarse con la crocidolita casi una adición de los efectos de los componentes cuarzo y amianto. Después de una inyección de crisolito y crocidolita las modificaciones del epiplón son más bien escasas i no se producen en otros órganos. En cambio la crocidolita causa adhesiones extensas del epiplón, el hígado, el espíenlo y el diafragma. Los polvos de asbestos deben ser clasificados como fibrógenosi no se produce un progreso en las modificaciones. Los cuerpos ferruginosos se encontraron solamente después de un período de pruebas de seis meses en el grupo sometido a las dosis más elevadas de crocidolita. Como modificaciones patológicas particulares en todos los^ grupos con crocidolita se observaron ascitis y quistes ovárlcos. No se poseen Indicaciones sobre la patogénesis de estas modificaciones. 524 PREVALENCE OF LUNG CHANGES, AND MORTALITY IN A BELGIAN ASBESTOS-CEMENT FACTORY L.M. Lacquet, L.van der Linden, J. Lepoutre Department of Pathophysiology; University of Leuven, Academisch Ziekenhuis Pellenberg, Belgium¡ Eternit N.V., Kapelle o/d Bos, Belgium The Eternit factory at Kapelle o/d Bos employs about 2000 workers and 400 clerks, and processes yearly about 35,000 tons of chrysotile, 3,000 tons of crocidolite, and 1,000 tons of amosite to manufacture a variety of asbestos-cement building materials and pipes. In the present study findings of yearly roentgenographic examinations of the lung and the mortality of workers are related to the age of the workers and to the duration and level of dust exposure. We looked for possible effects of exposure to asbestos in the way of pneumoconiosis, pleural changes, and malignancies. The risks incurred by people engaged in mining, milling, carding, and other manipulations of asbestos fibres are reasonable well documented, but little epidemiological data have been published about the asbestos-cement industry. In the factory studied, asbestos fibres are manipulated only while unloading the river boats, while carrying asbestos in paper bags (jute bags until 1975), and while preparing the mixture consisting of sand, cement, asbestos, and water. Some asbestos may be set free during these preparative stages and pollute other areas of the plant. In addition, dust of the asbestos-cement mixture, when dry, may become airborne. : 525: METHODS DUST CONCENTRATION. In 1969 the filter-membrane method for the counting of fibres In the air was Introduced in the factory. This technique was described by Holmes (1965) and by the British Occupational Hygiene Society (1968). The concentration of fibres was measured twice a year at many different sites, distributed throughout the factory. The sampling was done at mouth level, over a period of 8 minutes, and during working hours. We have considered the following five typical working areas, in decreasing order of business i area 4. which involves the handling of asbestos fibres, such as carrying asbestos bags, milling asbestos, preparing the asbestos-cement mixture; area 3, where asbestos-cement products are finished by the action of sawing, drilling, chafing, and the likei area 2. which Is situated between the previous two and where the asbestos-cement sheets and pipes are moulded, pressed, dried, and lifted off the mould) area 1. where very little dust exposure is expected, like the offices, area 0. which represents work outside the asbestos industry, with negligible dust level. Actual fibre counts obtained with the filter-membrane method are available for 1970 through 1976 Table It dust concentrations have been much higher In previous periods, but the actual values can be estimated approximately. We reasoned as follows i Since a roughly tenfold Increase in fibre concentration can be measured during a break-down of exhaust ventilators, or 526 as a consequence of negligence, a dust level of that magnitude probably reflects the conditions which prevailed before 1940, when little attention was being paid to dust control; no asbestos was available from 1940 through 1944, so we- assigned a zero concentration to these years; in 1945 some of the equipment was renewed, and between 1955 and 1965 the factory was given a major overhaul; minor improvements have been added since. In summary, we believe that the dust concentrations have followed a more or less logistic decay law, with an inflection point in 1960, which can be expressed by the formula c = co/(l + 1.16 ^ ), where c is concentration in fibres/ml, y is a number (year) between 1928-1977, and c Q is 0.4, 16, 24, and 100 fibres/ml for areas 1, 2, 3, and 4 respectively (i.e. roughly 10 times present day levels). Although it is somewhat arbitrary to choose this parti- cular function, it yields figures in compliance with the reasoning outlined above, and with the dust levels measured in recent years (Fig. 1 ) . FIBRE-YEARS. The degree of individual exposure to asbestos was expressed in fibres per ml multiplied by the duration in years, or "fibre-years" in short. Since employees may work consecutive- ly in different areas, fibre-years for any individual were calculated as "Z. (fibres/ml). , where i refers to the type of area and y to the year. The workers, and consenting clerks, were interviewed during the year 1975 by a social nurse, who filled in a questionnaire 527 on past and present work with emphasis on any kind of dust exposure (also noted were any kind of lung disease and the smoking habit). From these data we calculated individual fibre-years according to the above formula, and hence the fibre-years distribution of all intervieweesj extrapolating from this, the analogous distribution was obtained for all workers in 1963 through 1977 (29,366 man-years), bringing into account the annual changes in number enlisted and in dust concentration. DIAGNOSIS OF ASBESTOSES. The name asbestosis is used in this paper to designate a pneumoconiosis due to the inhalation of asbestos, and consisting in fibrosis of the lung interstitium and/or if the visceral pleura, according with the definition given by Becklake (1876)i the name does not cover other effects of asbestos exposure, for instance the thickening of the parietal pleura. All cases of asbestosis reported herein, were dis- covered with the help of radiographs, and any employee with small opacities on his chest roentgenograph was subjected to further investigation. The requirements for making the diagnosis of asbestosis were threefold« (a) the presence of irregular small lung opacities with profusion of at least l/.Ot and (b) the presence of at least two of the following abnormalities! ill defined outline of heart and/or diaphragm, clubbing of the fingertips, crackling rales audible over the lung bases, carbon monoxide transfer or vital capacity less than 76% of the predicted values. A decrease of vital capacity was disregarded it if could be attributed to some obvious restrictive lesions other than as- 528 bestosis, or to obstructive lung disease. The mere presence oí pleural plaques was not used as a criterion for asbestosis. ASBESTOSIS AND MORTALITY STUDY. The population studied consist of all male workers who, within the 15 years period of 1963 through 1977, worked in the factory for at least 12 months. Only for that group adequate medical and administrative records were available. The number of male workers for each of these years was obtained from the factory records; which yielded a total of 29,366 man-years. The age distributions could be obtained from factory records for the years 1975 (Table 1), 1976, and 1977; these were nearly identical, and the 1975 distributio was assumed to be representative for the whole period of 1963 tftmugh 1977. The female workers are not included in the mortal study, as they suffered only 3 deaths during the given period, which is not surprising as most female workers leave the factor before reaching the age of 50. ROENTGENOGRAPHIC STUDY. In 1975, 2,650 employees were enlisted of which 1,973 (74.5%) had both a history taken and a chest roentgenograph made in that same year; they are distributed as followst 1,963 male workers (85.5% of the enlisted), 214 female workers (81.4%), 78 male clerks (25.1%), and 2 female clerks (1.8%). The distribution with respect to age and exposure is given in Table 11. The yearly chest roentgenograph is compulsory for all workers, while clerks submit to this examination on a voluntary basis. 529 The ro ent Reno graphs consist of an antero-posterior view of the chest, on a full-size film (0.36 x 0.36m), taken at 60 to 80kV. The films were read jointly by two of us, as part of a routine industrial medicine program, and were always compared with the one taken the year previously! all previous films were at hand to be consulted in case of doubt. The roentgenographic findings were coded according to the extended system elaborated by the International Union Against Cancer. The irregular small opacities, were graded according to the full 12 point scale of the UICC /Cincinnati Classification (1970)i we considered the three normal subcategories! 0/-, 0/0, 0/11 and the three abnormal categories i 1, 2, and 3 (the subcategories were pooled because of the small numbers observed). The pleural changes were interpreted ast (a) pleural adhesion« (b) blurred contour of heart and/or diaphragm! (c) pleural plaquei and (d) calcified pleural plaoue. Three grades (1= minimal, 2= moderate, 3= marked) were noted and pooled for analysis because of the small number observed. Pleural adhesions are exudative sequelae, e.g. obliteration of the costo-phrenic angle. The pleural plaques comprise "hyaline" plaques and probably a few cases of post-exudative diffuse thickening, as it is not always possible to distinguish these two on a routine chest roentgenogram. Also noted were changes suggestive for cancer, tuberculosis, sarcoidosis, heart disease, active or inactive tuberculosis, and trauma (e.g. rib fractures, thoracotomy). 53o All causes of death were checked through the family doctor and/or a social nurse who visited the relatives (Belgian authorities never release individual information from death certificates). The one case of pleural mesothelioma was diagnosed by one of the authors with the help of J. Lauweryns, head of the department of pathology at the university of Leuven. Expected mortalities by age group and by cause of death were calculated from the yearly mortality rates for Belgium, available in the tables of the World Health Organisation for 1965 through 1975¡ data for other years were extrapolated. RESULTS Table III gives the number of chest roentgenograms with small lung opacities and pleural changes, by group of exposure. We saw no small opacities with profusion greater than 2. We pooled all grades of pleural changes because the numbers are small; grade 3 was scored only by the calcified plaques. We found 29 cases of asbestosis during the 15 years' period of 1963 through 1977 (Table VII). The total mortality, by age and by cause of death, is given in Table VIII, and details concerning the malignant neoplasm are given in Table IX. Among the cases of respiratory cancer there were three cancers of the upper airways, 17 cancers of the lung, and one mesothelioma of the pleura. 531 DISCUSSION FIBRE-YEARS We realize our estimates of dust concentrations prevailing in the past are good guesses as best. Nevertheless! it is unlikely that they would be off reality by more than an order of magnitude andi more important, the figures proposed have at least relative accuracy» the dust levels in areas where dry asbestos fibres are being handled is certainly higher than in other areas, and the dust level certainly was higher during the first 30 years than during the last 15 years of the factory's existence. The concept of fibre-years is useful if indeed harmful effects of asbestos are proportional both to the concentration of fibres in the air breathed, and to the duration of exposure. This appears to be a good approximation for the development of asbestosis (Murphy et al, 1971), of benign pleural changes (Rossiter et al., 1972), of lung cancer (McDonald et al., 1971), and even of mesothelioma (McDonald, 1978), for which there also is indirect evidence for a dose-response relationship from autopsy studies (Whitwell et al., 1977). Since workers may be employed In different areas for different periods and even end up as clerks, it was difficult to ignore the concept of fibre-years. A limitation of the fibre-years concept is that It takes no account of the level of first exposure. This should not invalidate our analysis very much, as in most cases the relatively heavier exposure also came first for two reasons i initial employment at the plant usually happened to be the dustier one, and for any kind of employment the dust level has decreased with time (Fig.l). 532 ROENTGENOGRAPHIC CHANGES We excluded 15 cases from the study, either because of a history of sarcoidosis or of exposure to silica dust, the roentgenographs changes of which would otherwise be interpreted due solely to asbestos exposure. The profusion of small lung opacities and of benign pleural changes correlate strongly with fibre-years and with age. We therefore examined, by age group, the linear trend in proportions (i.e. number with changes per number roentgenographed by fibre-years groups). The trends are significant for small lung opacities grades 1 and 2 (Table IV), and grade 0/1 (not shown, P = 0.001); the trend is also significant for pleural adhesion (Table V ) , and for pleural plaque (Table VI)¡ the trend is not significant for calcified plaque (not shown). To rule out the effect on our analysis for post-inflammatory pleural changes, unrelated to asbestos exposure, we reexamined the given trends in proportion after eliminating 175 cases with evidence of old or recent chest trauma (e.g. rib facture), tuberculosis (e.g. hilar calcification), or empyema. This did not alter the conclusions given above (for pleural adhesion then P = 0.008; for pleural plaque then P = 0.005). We confirm the study on asbestos-cement workers by Weill et al. (1977), who found dose-response relationship for small lung opacities. We now also find such a relationship for benign pleural changes, which had already been described in the case of asbestos miners (Weill et al., 1973, 75; Rossiter et al., 1972) and of shipyard workers (Sheers and Templeton, 1968; Harries et al., 1972). The prevalence of calcified plaques in our study is not 533 related to fibre-years, although the number of cases in which this lesion was seen may be too small to uncover the relationship. ASBESTOSIS The number of cases with diagnosed asbestosis increases significantly with the degree of exposure expressed in fibre-years (Table VII). We observed no case of asbestosis for an exposure below 100, and only one case in the range 100-200 fibre-years. Only two workers who never had handled free asbestos fibres (area 4) developed asbestosis, but their degree of exposure (starting around 1930) had nevertheless been high) 435 and 350 fibre-years, respectively (on account of work in area 3). • The present study thus indicates that the handling of asbestos-cement is less dangerous than the handling of the free asbestos fibres. However, less dust is generated in the former and therefore, from the present data, we cannot know whether asbestos-cement dust is less fibrogenic in se than free asbestos. MORTALITY The total mortality is not significantly different from what would be expected in a Belgian population of matched age and sex (Table VIII). There is, however, a significant excess mortality due to external causes, probably because factory workers are at higher risk of accident than the general population* indeed there were 10 occupational accidents, of which two were actually traffic accidents on the way to work. There is also an excess mortality, 53* not quite significant, due to non-malignant respiratory disease, which probably must be attributed to the seven deaths due to asbestosis (Table VIII). The mortality due to all malignant neoplasm does not exceed expectation (Table VIII), but there is a significant excess of deaths due to , and only to, digestive cancer (Table IX). A similar excess for digestive cancer, and not for respiratory cancer, was found by Van de Voorde et al. (1967), for workers employed in this same factory. Either this excess is due to asbestos ex- posure, or the workers studied differ from the general Belgian population. An argument against the effect of asbestos expo- sure is that we found no significant relationship between excess of digestive cancer and fibre-years (Table X ) . Since one might question the validity of comparing the mor- tality in a population of enlisted workers with the figures of national statistics, we have also made comparisons with internal case-controls. The principles of the method were explained by Liddell et al. (1977). In the present analysis, for each male worker who died of respiratory or digestive cancer, we selected four controls, at random, out of the group of all male workers alive at least one year after the date of expiration, and matched for age ± 1 year and date of enlistment + 1 year. We have compared the distribution of the cases and the controls with respect to dust exposure in fibre-years, which could differ only in the fibres/ml and not in the years« there is no significant difference (Table XI). This means that the dust exposure did not affect the mortality due to respiratory cancer and digestive cancer in a 535 significant way (eventhough the one case of mesothelioma is almost certainly related to the heavy exposure, and is included in the analysis). Table XII shows that the incidence of asbestosis has markedly decreased during the 15 years period of observation, which confirms the assumption of strongly decreasing dust concentrations 10 to 20 years earlier. On the other hand, the incidence of respiratory cancer, but not of digestive cancer, is increasing; since the dust concentrations have been decreasing and, moreover, we could not find a dose-response relationship, we believe this finding merely reflects the evolution in the Belgian population, where the incidence of lung cancer has been increasing, and that of digestive cancer is slightly decreasing. CONCLUSIONS The following is important with regard to the workers enlisted in the asbestos-cement factory we have investigated! (1) there is a strong dose-response relationship for asbestosis, and no case was observed for exposures less than 100 fibreyears ; (2) there is a dose-response relationship for roentgenographic small lung opacities, pleural adhesions, and pleural plaques; (3) the general mortality is not in excess of the national expected figures, but there is an excess of accidental deaths i (4) the mortality due to malignant tumor is not in excess of 536 the national expected figures¡ (5) there is no excess mortality due to respiratory cancer¡ (6) there is an excess mortality due to digestive cancer, which shows no dose-response relationship when compared with the national expected figures or with internal case-controls• 537 fibres/ml 100 - - ^ ^ area U 90 80 70 60 - 50 1930 Fig. 1 . 1940 1950 year 1960 1970 1380 Evolution with time of dust concentrations in four types of area in the plant as estimated according a logistic decay law ; points are mean values actually measured in area 4 ( o ) , area 3 ( • ) , 538 and area 2 ( + ) . REFERENCES Becklake , M . R . ( 1976 ) . Asbestos-related diseases of the lung and other organs : their epidemiology and implications for clinical practice . Amer.Rev. resp. Dis. , 114 , 187 - 2 2 7 . British Occupational Hygiene Society ( 1 9 6 8 ) . Hygiene standards for chrysoMIe dust . A n n . occup. Hyg. , 11 , 47 - 69 . Harries , P . G . , Mackenzie , F . A . F . , Sheers , G . , Kemp , J . H . , Oliver , T . P . and Wright , D . S . ( 1972 ) . Radiological survey of men exposed to asbestos in naval dockyards . Brit.J.industr.Med. , 29 , 274 - Holmes , S. ( 1965 ) . Developments in dust sampling and counting techniques in the asbestos industry . A n n . N . Y . A c a d . S c i . , 132 , 288 - 297 . Liddell, F . D . K . , McDonald , J . C . , and Tholas , D . C . ( 1 9 7 7 ) . Methods of cohort analysis : appraisal by application to asbestos mining . J.roy.statist. Soc.A. , 1 4 0 , Port 4 , 4 6 9 - 4 9 1 . McDonald , J . C . , McDonald , A . D . , Gibbs , G . W . , Siemiatycki , J . , and Rossiter , C . E . ( 1971 ) . Mortality in the chrysotile asbestos mines and mills of Quebec . A r c h , environm. H l t h . , 99 , 677 - McDonald , J . C . ( 1978 ) . Exposure relationships and malignant mesothelioma . Proceedings of Asbestos Symposium , 1977 , e d . H . W . G l e n , National Institute for Metallurgy , Randburg 1978 , pp. 49 - 64 . Murphy , R . L . H . , Ferris , B . G . , Burgess , W . A . , Worcester , P . H . J . , ond Gaensler , E . A . ( 1971 ) . Effects of low concentrations of asbestos : C l i n i c a l , environmental , radiologic and epidemiologic observations in shipyard pipe coverers and controls . New Engl . J . M e d . , 2 8 5 - 539 Rossiter , C E . , Bristol , L . J . , Carter , P . H . , Gilson , J ; C . , G r o i n g e r , T . R . , Sluis-Cremer , G . K . , and McDonald , J . C . ( 1972 ) . Radiographic changes in chrysotile asbestos mine and mill workers of Ouebec . Arch.environm, H l t h . , 24 , 388 - Sheers , G . , and Temple.on , A . R . ( 1968 ) . Effects of asbestos in dockyard workers . B r i t . med. J . , 3 , 574 - UlCC/Cincinnati Classification of the Radiographic Appearances of Pneumoconioses ( 1 9 7 0 ) . Chest , 58 , 57 - 67 . Van de Voorde , H . , Meulepas , E. , G / s e l e n , A . , en Koppen O . ( 1967 ) . Doodsoorzaken b i j de bevolking woonachtig rond en b i j de arbeiders werkzaam in een asbestverwerkende nijverheid in het noorden van Brabant . Acta rubere. pneumol.beIg. , 58 , 924 - 942 . W e i l l , H . , Zisktnd , M . M . , Waggenspack , C . , and Rossiter , C . E . ( 1975 ) . Lung function consequences of dust exposure in asbestos cement manufacturing plants . A r c h . environm.Hlth. , 3 0 , 88 - Whitwell , F. , Scott , J . , and Grimshaw , M . ( 1977 ) . occupations and asbestos- fibre Relationship between content of the lungs in patients with pleural mesothelioma , lung cancer , and other diseases . 54o Thorax , 32 , 377 - 386 . Table I DUST CONCENTRATIONS IN FIBRES/ml MEASURED IN FOUR TYPES OF WORK AREA AREA 1 YEAR mean 1973 - 1974 0.03 1970 1971 1972 1975 - 1976 0.05 x SD ( n ) x AREA 3 AREA 2 mean SD (n) mean SD (n) 2.3 0.7(4) - 2.1 0.4(4) 3.6 3.0 ( 8) 0.02(6) 0.02(6) SD = Standard deviation ; AREA 4 mean SD (n) 18.0 36.1 (33) 9.2 13.6 (39) 1.6 1.7(37) 2.4 2.3 (20) 10.8 22.-1 (115) 2.0 2.2(14) 2.2 1.7(15) 9.8 16.1 (85) 1.5 1.8(31) 2.6 5.8(23) 13.9 23.0 (47) 1.1 0.9 (31 ) 2.1 3.3(52) 11.2 22.2 (152) 1.3 1.4(27) 1.8 1.5(19) 10.7 25.0 (85) n = number of measurements . 541 Table II DISTRIBUTION BY AGE AND BY EXPOSURE OF WORKERS AND CLERKS EXAMINED anno 1975 FIBRE-YEARS AGE-GROUP TOTAL 15-34 35-44 45-54 186 180 94 1062 259 0- 49 602 50- 55-65 99 34 96 94 35 1 0 0 - 199 1 121 162 67 351 2 0 0 - 399 0 22 137 82 241 4 0 0 - 799 0 1 17 13 31 800-1599 1 1 3 9 14 638 427 593 300 1958 total analyzed : total roentgenographs 1973 cases of silicosis and sarco idosis eliminated : 5^2 15 Table III NUMBER OF ROENTGENOGRAPHS LUNG CHANGES FOUND IN 1 958 EMFLOY'ES EXAMINED anno 1975 SMALL OPACITIES PLEURAL CHANGES FIBRE-YEARS 0/- 0/0 0/1 1 2 ., . adhesion 1,2 0-49 50- 128 886 46 2 0 36 contour plasue celo': - '': piar,-.;'.? 0 15 4 blurred- 1,2 1,2 1 , 2. : 99 3 225 29 2 0 15 0 7 7 1 0 0 - 199 5 302 35 9 0 34 3 23 6 200 - 399 5 184 40 11 1 30 2 16 6 4 0 0 - 799 0 22 6 5 8 0 0 - 1599 1 11 142 1630 total changes 2 1 157 1 27 1 7 1 0 3 0 2 125 6 5*3 0 1 67 0 23 Table IV PREVALENCE IN % OF FIBRE-YEARS s - t - u LUNG OPACITIES GRADES 1 AND 2 anno 1975 x AGE - G R O U P 15-34 35-44 45-54 TOTAL 55-65 0- 49 0 1.1 0 0 0.2 50- 99 0 0 1.1 2.9 0.8 1 0 0 - 199 0 0 2.5 7.5 2.6 2 0 0 - 399 0 4.5 2.2 9.8 5.0 4 0 0 - 799 0 0 5.9 15.4 9.7 800-1599 0 0 33.3 0 7.1 total % 0 0.7 1.7 5.3 1.5 linear trend with pooledregressioncoefficients : P = 0.001 x median taken as the score 544 Table V PREVALENCE IN % OF PLEURAL ADHESIONS , anno 1975 FIBRE -YEARS" 0 - 4 9 TOTAL AGE-GROUP 15-34 35-44 1.2 3.2 45-54 55-65 6.7 11.7 3.4 5.8 99 0 4.2 6.4 14.3 100- 199 0 3.3 12.3 14.9 9.7 2 0 0 - 399 0 4.5 11.7 15.9 12.4 4 0 0 - 799 0 0 17.6 30.8 22.6 800 - 1599 0 0 33.3 22.2 21.4 1.1 3.5 9.8 15.0 6.4 50- total % linear trend with pooled regression coefficients : P = 0.002 x median taken as the score 545 Table VI PREVALENCE IN % OF PLEURAL THICKENING , onno 1975 FIBRE-YEARS x AGE - GROUP 15-34 35-44 45-54 TOTAL 55-65 0- 49 0 0.5 3.3 8.5 1.4 50- 99 0 0 6.4 2.9 2.7 1 0 0 - 199 0 2.5 8.0 10.4 6.6 2 0 0 - 399 0 0 9.5 3.7 6.6 4 0 0 - 799 0 0 17.6 15.4 16,1 8 0 0 - 1599 0 0 33.3 11.1 7.1 total % 0 0.9 7.1 7.3 3.4 linear trend with pooled regression coefficient»: P =0.01 x median token as the score 546 Table VII INCIDENCE OF ASBESTOSIS anno 1963 THROUGH 1977 FIBRE-YEARS X 0-49 50- number % 11 340 0 0 99 4 094 0 0 100- 199 5 791 1 0.02 2 0 0 - 399 6 629 7 0.11 4 0 0 - 799 1 179 8 0.68 8 0 0 - 1599 307 10 3.26 1600-3200 26 3 11.54 total 29 29 366 Inear trend in proportions x NEW CASES MAN-YEARS : P < 10 median taken as the score 547 < I— o o oo co CM OS S 2 5 M h- Q M ¿ z>S O v> U 3 CM O-' 3 < (- O <o 8, Z «o < z o C- 0* MJ — z o z O — -<>•<* Ji-S H-E a o«t5 m oo 4 « N v o o vi S fc* Z li z < z ,— O tu co — </> — = S « 2 -JI3 < iiü 20 co r<» oo o CM « S 5 ^ CO •O CM •* -* — CO <0 — M} CM M) O ^ O MJ 53 co — CK >0 co o> CN CN o. .5 S S 5 S 53 0°= <o io <o >o vt <o IM n ^ «i UJO 1! "8 ir 5^P O 8 I e e ç Table IX DEATHS DUE TO MALIGNANT NEOPLASM OBSERVED IN MALE WORKERS BY AGE AND SYSTEM AFFECTED ( 2 9 366 man-years) AGEGROUPS respiratory digestive nervous lymphoid & hematopoietic other not specified TOTAL 15-24 1 25-34 35-44 2 45-54 6 3 14(1) 55-65 1 2 1 14 4 2 17 4 2 2 total : 22 expected! 22.3 11.8 2.1 3.9 2.4 P (2) N.S. 0.04 0.10 N.S. N.S. (1) (2) . 1 includes one case of pleural mesothelioma in a Poisson-distribution with the expected number as the mean . 5^9 11 34 1 12.9 48 55.4 Table X DEATHS OF MALE WORKERS DUE TO RESPIRATORY AND DIGESTIVE CANCER BY EXPOSURE GROUP FIBRE - YEARS ' MAN-YEARS 1963-77 . RESPIRATORY CA. 2 expected observed DIGESTIVE CA. observed expected 2.76 0-49 11340 6 5.16 4 50-99 4 094 3 2.43 1 1.32 1 0 0 - 199 5 791 5 4.60 1 2.46 2 0 0 - 399 6 629 4 7.47 7 3.93 400-799 1 179 1 1.95 2 1.00 800-1599 307 2 0.57 2 0.29 1600 - 3200 26 l3 0.17 0 0.04 22.35 17 total 29 366 linear trend In proportions : 1 22 P =0.22 median taken as the score 2 adjusted for age distribution within fibre-years groups 3 pleural mesothelioma 55o 11.80 P=0.16 2 Toble XI DISTRIBUTION BY EXPOSURE GROUP OF CANCER CASES AND OF MATCHED INTERNAL CONTROLS ( 4 per cose ) FIBRE-YEARS" 0-49 RESPIRATORY CANCER cases controls 6 3 DIGESTIVE CANCER cases/total cases controls cases/total 20 a23 4 16 0.20 17 0.15 1 5 0.17 a42 1 14 0.07 50- 99 100- 199 5 7 200- 399 4 32 ail 7 20 0.26 400- 799 i 8 an 2 8 0.20 800 - 1599 2 4 0.33 2 5 0.29 l*x 0 1.00 17 68 1600-3200 total : 22 88 linear trend in proportions : x xx p = aii median taken as the score pleural mesothelioma 551 P = 0.23 Table XII NEW CASES OF PERIOD ASBESTOSIS,AND DEATHS BY CANCER MAN-YEAR S ASBESTOSIS MALIGNANT NEOPLASM respiratory digestive % % other % % 1963-1967 9 805 13 0.13 5 a05 6 0.06 2 0.02 1968-1972 10 423 ii an 8X a08 6 a06 4 0.04 1973-1977 9 138 5 0.05 9 aiO 5 0.05 3 0.03 29 366 29 0.10 22 0.07 17 a06 9 0.03 to fai x includes one case of pleural mesothelioma 552 Cambios rontp.enop.rá fieos del rjnlmón relacionados con la exposición al polvo de los empleados de una fabrica de fibrocemento. L. M. Lacquet y J.Lepoutre, M.D. (Bélgica) En una fábrica de fibrocemento que funciona desde 1905 y emplea 2.400 obreros y 400 empleados se ha examinado a codo el personal a partir del I o . de mayo de 1963. til estudio muestra que para el período 1963 a 1976 se produjeron 23 casos de asbestosis, 1 caso de mesotelioma pleural, 7 casos de cáncer de pulmón, 2 casos de cáncer gastrointestinal y 12 casos de tuberculosis evolutiva. El diagnóstico de la asbestosis se basó no sólo en el rontgenograma de pulmón sino también en la espirometría, en la prueba de difusión del óxido de carbono y en exámenes clínicos y de laboratorio relacionados con la cantidad de oolvo en la fábrica. El promedio de tiempo de exposición de los 23 obreros con asbestosis era de 24 años, y la intensidad de la exposición era de 1.077 fibras-año. Es interesante señalar que no se encontró ningún caso de asbestosis con menos de 100 fibras-año. La asbestosis se encontró únicamente en los obreros que trabajaban con amianto puro. La prevalencia de asbestosis en ìa fábrica no se ha modificado en los últimos 13 años. En los últimos tiempos han ido disminuyendo claramente los nuevos casos. Se han encontrado menos casos de lo previsto de tumores malignos de pulmón, durante este período de trece años y medio, esto es, se detectaron sólo ocho casos de los 14,6 esperados. También el número de cánceres gastrointestinales es ligeramente inferior al esperado. 553 vi/7 RIGIDITE OTAPHRAnniTinilF CPRRFLATTPM R A n i P I . P n i ^ M F A. HIRSCH, L.ni FT FXPPTTTTPM A L'O^TA^TF FT rHTRHrinT , "AI F HAMS 47 HEflZA, CI. HANnnLO, 3. : T'lPRAPnTPHIFS RTGMCM. S e r v i c e de Pnaumolooie, H o o i t a l Intercommunal, Créteil France. L'atteinte pleurale radioloqiciue (énaiRsissement pleural, nlanue pleurale hyaline, calcification pleurale) est classiquement considérée comme un bon indice d'exposition a l'amiante (1,2,3). Au cours des examens radiolooiques effectués chez des sujets exposés ou ayant été exposés a l'amiante, nous avions constaté un sinne fréquent et non encore décrit : une ou plusieurs rectitudes seqmentaires d'une coupole, inter- rompant ou remplaçant la courbure normale du diaphranme, et non associées a un épaississement ou a une hyperdensification (fiqure. 1 ) . L'objet du présent travail est de vérifier que ce signe rediologique correspond a une modification anatomique du diaphragme, d'établir sa relation avec une exposition professionnelle a l'amiante, et d'étudier sa sensibilité, en précisant l'intensité et la durée de l'exposition profession- nelle, la longueur de la période de latence, et sa fréquence par rapport aux autres anomalies pleurales et/ou parenchymateuses observées lors de l'exposition a l'amiante. Matériel et méthodes: Ce travail porte sur 47 observations (43 hommes et 4 femmes, âgés de 20 a 75 ans, age moyen : 57,6 - 4) de thoracotomies consécutives. Les patients opérés pour mesothelioma ont été exclus, la majorité des malades ayant été opérés pour cancer bronchique (37 cancers bronchiques et 10 autres causes). 555 Avant 1'intervention, l'un de nous (FI.PI.) a procédé a une enquêta a l'aide d'un questionnaire standardisé, constitua de questions a réponses fermées, portant sur le curriculum laboris ot l'existence d'une exoosition professionnelle a l'amiante (résultats tableau 1). Il a ainsi été possible de déterminer la durée de l'exposition et celle de la période de latervte s'écoulant entre le début de l'exposition et la date de la thoracotomie. L'existence d'une exposition professionnelle était indépendante du motif de la thoracotomie. D'autre part, il a été impossible, lors de l'étude des relations entre exposition et manifestations pleurales radiolooinues et chirurnicales, de distinnuer entrB expositions définies et suspectes, du fait de la faiblesse des effectifs et du caractère subjectif de cette distinction qui ne reposait que sur la connaissance par le sujet d'une exposition professionnelle a l'amiante. Des radiooraphies thoraciques frontale et latérale de routine ont été effectuées dans tou3 les cas. Elles ont été analysée par deux lecteurs (A.H et L«.n.) selon la Classification internationale BIT U/C 1971 avec arbitrane anres discussion. Les lecteurs précisaient en cutre l'aspect radiolonique des diaphrapmes, en mentionnant l'existence d'une rioidité, son siane, sa taille, snn aspect calcifié nu non. Lors rie la thoracotomie, le chirurpien inspectait soinneusement la olevre pariétale, dans la rénion costale et diaphraomati que, et notait sur un shéma les anomalies observées. Smiles les rinidités diaphraomatiques observées du enté ooéré et sur les deux incidences frontale et latérale ont été retenues nnur l'étude des corrélations anatnmn radiolorini.ier!, F?n nutre, una biopsie pulmonaire et une étude minéralooinun sur la nlevr'o et le narenchyme ont été effectuées, dont les résultats seront publiés ultérieurement. 556 Résultats : Nous av/ons noté dans 30 ?•> des cas (14 cas) des rioidités diaphragmatiques visibles sur les deux indidences radioloqiques, des ôpaississements pleuraux uni ou bilatéraux dans 13 % des cas (6 cas), des calcifications pleurales, de sieoe diaphraqmatique ou costal, uni ou bilatérales dans 14 % des cas (7 cas, dont 4 siépeant du coté de 1'intervention), et 3 aspects de fibrose parenchymateuse. Sur le cliché frontal, les rigidités diaphraqmatigues étaient de siBqe moyen 19 fois, externe 7 fois, interne 4 foi9, enfin sur toute la coupole dans 1 cas. Sur le cliché latéral, le siane était moyen 20 fois, postérieur 11 fois, antérieur 2 fois, sur toute la coupole dans 2 cas. Les dimensions de la zone raide dépassaient 5 cm dans 18 cas sur l'incidence latérale, dans 16 cas sur l'incidenca frontale. Lors de la thoracotomie, dans 38 % des cas (18 cas) il existait des plaquea de la plèvre pariétale, de localisation diaphraqmatique at costale dans 9 cas, diaphraqmatique dans I cas, costale dans 8 cas. Le tableau 2 montre 80 % de concordance entre rigidité . diaphraqmatique sur les incidences frontale et latérale et plaque diaphraqmatique a la thoracotomie (6 cas) et absence riqidité radioloqique et de plaque a l'intervention (32 cas). II existait 5 faux positifs (rigidité radioloqique aans plaque a l'intervention) et 4 faux négatifs (plaque chirurgicale sans rigidité radiologique). Les tableaux 3 et 4 indiquent 1 B 9 relations de9 rigidités diaphragmatiques radiologiquea et des plaques diaphraomatiques chirurgicales avec l'exposition • l'amiante. Le tableau 3 montre la fréquence des anomalies radiolooiques dans les deux groupes, normalité du cliché et riqidité diaphraqmatique 557 étant si"nifinativement différentes dans les deux oroupes. Le tableau 4 montre la fréquence relative des plaques chiruroicales dans 1 B 3 deux nroupes, 46 % des sujets exposés ayant des plaques visibles a l'intervention, de siene diaohranmatique et costal dans 9 cas sur 17. La durée d'exposition chez les sujets porteurs de plaques chiruroicales était en moyenne de 19,6 ans - 12,6, contre 16,9 ans - 7,56 chez les sujets exposés indemnes de plaquen chiruroicales, cette différence n'étant pas siqnificative. La période de latente chez les sujets exposés a l'amiante indemnes de plaque pleurale a la thoracotomie était de 25,9 ans - 13,9, contre 39,3 ans - 5,9 chez les sujets exoosês porteurs de plaque pleurale chiruroicale, la différence étant sinnificative a 0.001. La période de latente était sensiblement identique pour les sujets Bxposés présentant une ridioité diaphraomatique radioloqique (37,6 an3 5,2), une calcification pleurale radioloqique (37,2 - 6,3), ou un énaissement pleural radioloqique (35 ans - 5,5). Par contre, elle était nettement moindre chez les sujets a radionraphie normale (27,6 ans - 10,1) sans qu'il soit possible d'effectuer un test statistique. Discussion: Les calcifications pleurales sont observées dans 0,15 a 0,20 r'> des radiooraphies thoraciques de routine dans la population étudiée (l). Elle sont actuellement considérées comme le témoin d'une exposition pasaée a l'amiante ou au talc, rsi l'on a éliminé un antécédent pleural infectieux ou traumatique (2,3). Elles sont plus fréquentes que les anoma- lies onrenchymateuses, représentant le seul sinne radiolonique dans la moitié des cas (4,5 , 6, 7 ) . Des plaques pleurales ont 558 pu etra observées a l'état endémique dans une rénion bulnare dont le sol était riche en matériaux fibreux (8). Leur va- leur morbide repose sur la olus orande fréquence chez les ouvriers exposés a l'amiante et porteurs de plaques pleurales, de l'asbestose (1), du cancer bronchique (9), et du mésothéliome (1,9). On a rapporté un cas de mesothelioma développé au contact d'une plaque (10). La fréquence des plaques pleurales au cours des thoracotomies consécutives effectuées dans un service rie chirurnie thoracique a antérieurement été ««tintée a 10 % (11).Dans des Séries autopsiques consécutives de sujets adultes, les plaques ont été constatées avec ries fréquences variables, allant de 2,7 & dans une série de 1B29 autopsies faites chez des vétérans (12) a 32 % chez les ruraux et 52 % chez les citadins dans une série de 438 autopsies effectuées dans 3 hôpitaux (13). La fréquence constatée dans la présente étude se rapproche de cas derniers pourcentages. Il était indispensable de vérifier les relations entre rigidité diaphragmatique et aspect anatomique du diaphragme. En effet, l'intérêt de cette confrontation eat illustrée par un travail récent dans lequel 10 % des asbestoses histoloçiquement démontrées s'accompagnaient ment normal (14), d'un cliché thoracique riqoureuse- L'étude comparative de la riqiditô diaphra- matique Bt de l'aspect macroscopique du diaphragme lors des thoracotomies consécutives a montré une concordance satifal*» sante. Cependant, 4 plaques chirurnicales sur 10 n'ont pas été vues sur les films, et 5 rigidités diaphraqmatiques sur 11 ne correspondaient pes a des plaques chirurnicales. Ces discordances font discuter les limites das môthories radiolonique et chirurgicale. De même que les épaissements pleuraux sont dif- ficiles a distinguer du tissu oraisseux snus pleural (15,16), B5 % ries plaques pleurales'hyalInes sont invisibles sur les films (2). Dans une série d'asbestoses autopsiées, l'examen 55? histnlnnj.nua rlu diaphraonte a permis rie constater des microcalcifinations chez 86 '.•' des sujets, la frequence des calcifiontinns radiolnninues ne déoassant pas 9 75 (13). L'utilisation d'incidence nbliaue (17) ou des ultrasons (18) a été prnpnséee nour améliorer la détection des plaques. L'asnect macroscopique normal d'une coupleriiaphranmatiquene présume pas non plus de son intéorité histolonique. Los nlaquos pleurales pariétales sont habituellement de siepe costal et diaphranmatique (19). Pour ces dernières, elles sont localisées au niveau du centre tendineux du diaphranme, ce qui est a rapprocher du siepe habituellement moyen des rinidités diaphranmatiques rapportées dans cette étude. Le mécanisme de production des plaque9 reste obscur et doit tenir compte de leur situation sous-pleurale, de l'intégrité* fréquente du mesothélium qui les recouvre, de l'abscence de symphyse pleurale ainsi que de leur sieqe, au nivBau du centre tendineux ppur les plaques diaphranmatiques, A en renard des cotes pour les plaques de la paroi (20). Les fibres d'amiante pourraient soit minrer au travers du poumon (21), soit miprer a contre-courant par les lymphatiques thoraciques et intercostaux (22). Nous nous sommes heurtés aux difficultés habituellement siqnalées Dar les utilisateurs de questionnaire pour préciser la ou les professions exppsées a l'amiante, l'intensité de l'exposition, sa durée exacte ainsi que celle de la période de latence (23). En définitif, nous n'avons ou distinquer que 2 nroupes, exposés et non-exposés, l'exposition étant toujours de niveau faible au moyen. Entre ces 2 nroupes, les différences sont sionificatives pour la normalité du cliché 56o et l'existence, chez les sujets exposés d'uno rinidité diaphraomatique nues sur les incidences frontale et latérale. Par contre, elles sont peu sionificativ/es pour 1ns planues costale et/oudiaphragmatiqueconstatées par le chirurnien. Des réserves s'imposent toutefois, compte tenu notamment de l'abscenca d'une population témoin, les sujets non eapssés étant dans l'ensemble plus jeunes (aqe moyen : 51 an3 - 13) que les sujets exposés (ane moyen : 59 ans - 12,5). Il est d'autre part nécessaire, pour étudier la spécificité de ce sinne, de préciser sa fréquence d'une part chez des témoins appariés pour l'aae, le sexe, la consommation de tabac,l'état respiratoire, et d'autre part dans diverses conditions dans lesquelles l'exposition aux fibres n'intervient pas. fl l'exposition de la période de latence chez les sujnts exnnsés porteurs de plaques chirurgicales, nous n'avons pas mis. en évidence de différence entre durée d'exposition et période de latence pour lea anomalies pleurales radioloniques et chirurgicales. On sait que la durée d'exnosition neut être tres breve, quelques mois (2à) ou même quelques semaines pour les calcifications pleurales. La période minimale de latence pour les plaques calcifiées, observées en renie générale chez les sujets de plus de 50 ans (24), serait de 18 a 20 ans (4), peut être beaucoup plus courte, inférieure a 8 ans (7). Le fait qu'il n'a pas été possible de mettre en evidence une différence entre nos deux groupes de sujets peut s'expliquer par notre recrutement, la majorité des maladen étant onérép pour un cancer bronchique, et présentant donc une période de latence tras supérieure a la période de latence minimale des calcifications pleurales. La lecture de clichés séquentiels permettra de préciser la durée s'ôcoulant entre exposition et anomalies radiologique pleurales. Il est vraisemblable que l'aspect de rigidité précède la calcification dianhraqmatique (24). 561 La si^nif icat.i on rip la ri ni dite dianhranmatique comme indice nréc.ncn at/ou sensible ri'exoosition a 1 * amiante nécessite d'uno part uno annrnchn technique permettant, sa recnnnaiasancfi simplp, d'autre part dos études complémentaires précisant la snéfificité, la sensibili tí et la fidélité de ce sirne. On nourra alors eovisaper de l'inclurn dans la classi- fication radiolooique internationale des pneumnnonioses, dont on a soni inni In caractère inadapté Pour les mapifnstatinps pleuralnn liées a .1 'exnnsiti on a 1'amiante (75). Remerciements: Les conseils du flncteur PERDRIZET (Groupe Maladies Respiratoires - Institutut natinnal de la santa et de la Recherche médicale) nnus ont Até tres utiles lnrs de la rédaction du manuscrit. flous remercions les Docteurs RTSSC1N, CHAPANEIX, GUILLE et LflfinE nui ont opéré les malades, et ont décrit soigneusement les modifications de la plèvre. 562 nTRLinnaAPmc KLETNFELu, PI. (1966) Pleural ralniflcat.ion a.i sinn nf silicatosis. Ann. 3. Fl. S c , ?51 : 215-224. HOMRIHANF:, D. n»R; I.ESSOF, L.; RICHARDSON, P.C. (.1966) Hyaline and calcified pleural plagues as an index of exnosure to asbestos. A study nf rartinloniral and pathnlonical features nf 100 cases uith a consideration of epidemiolony. Rrit. med. 3., 1 : 1069-1074. MiWRATIL, Fl., TRIPPE, F. (1972) Prev/alence nf nleural clacificatinn in persons exposed to asbestos dust, and in the aeneral population in the same district. Environ. Res. 5 : 210-216. SELIKOFF, 1.3. (1965) Occurrence of pleural calcification amonn asbestos insulation workers. Ann. Neu York Acad. Sc. 132 : 351-367. FREUNDLICH, I.n., GREENING,. R.R. (1967) Asbestosis and associated medical problems. Radiology, 89 : 224-229. KIVILU0T0, R. (1970) Asbestosis : aspects of its radiological features. Pneumoconiosis Proceedings of the International Conference, 3ohannesbouro 1969, 1 vol., Cape Toun Oxford University Press 253-255. FLETCHER, D.E. (1911) Asbestos-related chest disease in Joiner9. Proc. Roy. Soc. ned., 64 : 837-838. RURILKOV, T., FIICHAILOVA, L. (197Ö) Asbestos content of the soil and endemic pleural asbestosis. Environ. Res. 3 : 443-451. FLETCHER, O.E. (1972) A mortality study of shipyard worker uith pleural plaques. Brit. 3. Industr. fled. 29: 142-145. LEWINSOHN, H.C. (1974) Early malionant changes in pleural plaques due to asbestos exposure : a case report. Brit. 3. Ois. Chest 68 : 121-127, HERTZOG, P., TOTY, L., PERSONNE, Cl (1972) Plaques pleurales .pariétales fibrohyalines. 3. Franc, ned. Chir. Thorac. XXVI : 59-70. ROBINSON, 3.3. (1972) Pleural plaques and splenic capsular sclerosis in adult male autopsies. Arch. Pathol. 93 : 118-122. 563 HFiiRpiAtl, L. (1966) Asbestos bodies and oleural plaques in a finnish series of autonsy casus. Acta Path. Microbiol . Scand. Suppl. 101 : 1-107. E P L m , G.R.; rie LOUD, T.C.; GAENSLER, E.A. (1978) Normal chest roentnenonrams in chronic diffusa infiltrative luno disease. N. Enn. 3. («led. 298 : 934-939. CLOCK, M.C., TUTGC, H a . , BALL, M.F. et coll (1972) SHB00US borderinn the luno on radiooraphs of normal and obese persons. Thorax 27 : 232-238. «IX, U.A. (1974) Extrapleural costal fat. Radiology 112: 563-565. riAKENZIE, F.A.F., HARRIES, P.G. (1970) Chanoino attitude to the diannosis of asbestos disease. 3. Roy. flav. Fled. Serv. 56 : 116-123. Symposium nn the radio.l.oov of onaumoconiosis, Pneumoconiosis Prnceedinnr. of the International Conference, 3ohanne5bourn .196°, 1 un].. , Gape Toun Oxford University Press, 197Ô. 279. RORERTS, U.C., FERRANS, V.3. (1972) Pure collaoen plaques nn the dinohranm and pleural Ghost 61 : 357-360. THQflSONv 3. G. (197P) The pathogenesis of pleural plaques. Proceedings of the International Conference, Johannesbourn 1969, lvol., Caoe Toun Oxford University Press, 138-1¿1. KIVILUOT0, R. (1960) Pleural calcification as a roentnenolonic sion of nonoccupational endemic anthoohyllite asbestosis. Acta Radio, Suppl. 194. TA SKI NEH, E., AHLFIAN, K., UIIKERI, PI. (1973) A current hypothesis of the lymphatic transport of inspired dust to the parietal pleura. Chest 64 : 193-196. SAMFT, 3.n.: SPETZER, F.F.: GAENSLER, E.A. (1978) Questionnaire reliability and validity in asbestos exposed uorkers. Oull. Euron. Phvsiopath. Resp. 14: 177-1B8. SARGENT, U.E.; 3RC0RS0N, G.: WILKINSON, E.É. (1974) Oianhranmatic pleural calcification fnlloui.nn short occupational nxnosuro to asbestos. The Am. 3.of Rnentnenol., 115: A73-47". npHLIG, I'. (1970) The problem of ashestosls in relation to thn International Classif icnt.i nn nf Radinnraohs in 564 pn«?umncnni nsirs, Pnnnniornni.ORÌs PrncRnd.innr> o f International thn H n n f e r n n r n , Hnhsnnprïhmirn 19fi9, 1 v n l . , Caon Tnun P x f n r r i U n i v e r s i t y 565 Prrr.s, ?Af)-?ri?. TABLEAU 1 - PROFESSIONS RETENUES EN RELATION AVEC L'EXPOSITION A L'AMIANTE CHEZ 47 PATIENTS THORACOTOMISÉS EXPOSITION A L'AMIANTE PROFESSIONS RETENUES DÉFINIE + SUSPECTE* N = J0 N = 27 MAGASINIER PLOMBIER MANOEUVRE CHAUDRONNIER CARRELEUR INDUSTRIEL DU BOIS FRAISEUR/ TOURNEUR CHANTIER NAVAL SERRURIER REPASSEUSE GARAGISTE BONNETIER PCMPIER SOUDEUR CHARPENTIER PROTHÉSISTE DENTAIRE INGÉNIEUR EN FONDERIE N-JCT 3 3 3 1 1 0 0 0 H 2 CALORIFUGEUR-CHAUFFAGISTE MAÇON ELECTRICIEN NON EXPOSÉS* 0 0 0 0 0 0 0 0 0 0 0 0 10 + DÉFINIE : EXPOSITION A L'AMIANTE CONNUE PAR LE MALADE + SUSPECTE : EXPOSITION A L'AMIANTE POSSIBLE, IGNORÉE PAR LE MALADE + NON EXPOSÉS : AUCUNE EXPOSITION PROFESSIONNELLE A L'AMIANTE i-|+ : 9 CAS :;nr." EXPOSES : DOCUMENTES ET I CAS OU L» INTERROGATC1IRC « ETE IMPASSIBLE 566 TABLEALL2 - ELfiQUE.DLAPHRAfflfiriQUL CHlRURGlCALLi E I B J G l ü l t í .DlâPHFWïWIQlJE RAMOLOGIQUE. HCMPLATERALE VUE SUI LES INCIDENCES FRONTALE .ET LATERALE CHEZ 4 7 PATIENTS JTORACOTQMJSES \ RIGIDITÉ \ + DIAPHRAGMATIQUE - + P- \RADIOLOGIQUE PLAQUE \ DIAPHRAGMATIQUEX CHIRURGICALE \ + 6 H 0,01 - 5 + 2 567 32 TABLEAU 3 - ANOBLIES RADIDLOGJQUES UNI OU.BILATEBALES E I EXPQSJTJON PROFESSJONNELLE CHEZ 1 7 PATIENTS THORACDTQMISÉS ^ s . EXPOSITION À NON-EXPOSÉS EXPOSÉS N-37 + p= N-10 ^NJ/AMIANTE N (Z) N CD 16 W3) 9 (90) 0,05 M (38) 0 (0) 0.06 7 a® 0 (0) 4+ EPAISSISSEMHNT PLEURAL 5 (13) 1 (10) t++ FIBROSE PARENOWE 3 (8) 0 (0) 4+ RADIOLOGIE ^ X . I.T.N. RIGIDITÉ DIAPHRAGMATIQUE HOMO ET/OU CONTROLATÉRALE À LA THORACOTCMIE CALCIFICATION PLEURALE + -H- ^2C EFFECTIF CALCULE INSUFISANT POUR EFFECTUER LES TESTS STATISTinUES 568 TABLEAU 4 - PLAQUE PLEURALE CHIRURGICALE ET EXPOSITION PROFESSIONNELLE CHEZ 17 PATIENTS THORACOTCMISES . + \ EXPOSITION A ^SL'AMIANTE THORACOTDMIE ABSENCE DE PLAQUE ^ V EXPOSES N = 37 N 20 NON-EXPOSES p = N = JD ÖD N (X) (90 9 GO) 0.09 PLAQUES PLEURALES + 17 ^.2c 569 <«) l (10) Uigidez del diafrapjna entre las personas expuestas al asbesto i correlación entre los exámenes radiológicos v el aspecto real en 47 toracotomias. A. Hirsch, L. di Menza, M. Mangold, P. Sebastian y J. Bignon (Francia) Se ha observado rigidez del diafragma entre personas sujetas a una exposición baja o media al asbesto. A fin de estudiar la relación entre la rigidez del diafragma y la exposición al asbesto, hemos comparado la incidencia de esta manifestación radiológica con el aspecto real del diafragma en las intervenciones quirúrgicas (35 carcinomas pulmonares y en diez casos otras causas, con exclusión de la mesotelioma). Se observó una rigidez del diafragma en 23 por ciento de los exámenes por rayos X y se hallaron placas pleurales del diafragma en 21 por ciento de las toracotomías. Los resultados de los exámenes por rayos X concordaron con la realidad en 80 por ciento de los casos (6 casos positivos y 32 negativos). Se estudia la relación entre la manifestación radiológica y la existencia de esta anormalidad habida cuenta de la exposición al asbesto, procediéndose a la correspondiente evaluación sobre la base de los antecedentes profesionales y el número de cuerpos ferruginosos presentes en los pulmones o en los esputos. 57o THE PATHOLOGICAL EFFECTS OF ASBESTOS CLOUDS OF DIFFERENT FIBRE DIMENSIONS ON THE LUNGS OF RATS J. M. G. Davts, S. T. Beckett, R. E. Bolton, Paula Collings United Kingdom For some years now it has been suggested that the levels of pulmonary fibrosis and neoplasia resulting from asbestos inhalaion depend on a number of different dust parameters. Fibre length and the number of fibres per unit mass of dust have been both suggested as important and so has the duration of inhalation. It is also thought possible that short periods of exposure to very high levels of dust may be more dangerous than continuous exposure to low levelSf although the same dust mass is inhaled in both instances. The first studies indicating the importance of fibre length were reported by King et al., in 1946. These workers administered chrysotile fibres, cut on a special microtome at lengths of 15^ and 2.5^ to rabbits by intratracheal Injection. They reported a greater tissue reaction from those animals that had received the long-fibre sample. Similarly in 1951 Vorwald et al reported that animals which had inhaled chrysotile fibres in the 20 - 50/J range had more pulmonary fibrosis than those breathing only fibres below 3ju in length. studies using both the In 1968 Klosterkötter extended these intraperitoneal and intratracheal in- jection of crocidolite and chrysotile. Some dust samples had a very high average fibre length while other had been grounded to an average length of less than 5/J. The short-fibre samples produced little fibrosis in either site while the long-fibre 571 specimens resulted in considerable fibrosis in both regions. The importance of long fibres was further emphasised by Timbrell and Skidmore in 1968 and Webster in 1969 using inhalation techniques. In 1972 Davis reported a series of experiments in which several type of mineral fibre were administered to mice by intrapleural injection. This series of dusts included standard UICC chrysotile and chrysotile fragmented by ultrasonic treatment until all fibres were below 1/J in length. While long-fibre samples produced massive fibrosis, the short-fibre specimens produced almost no reaction. Very similar results were obtained by Wright and Kuschner in 1975. These authors injected a number of types of mineral fibre intratracheally into guinea pigs. Each of the minerals was prepared in both long and short-fibre forms and crocidolite asbestos was included. In all cases the long- fibre samples resulted in marked fibrosis while the short-fibre specimens produced only a macrophage reaction. There is considerable evidence that the neoplastic as well as the fibrogenic potential of asbestos and other mineral fibres is also dependent on fibre length with long-fibre dust samples producing more tumours than short. reported that the In 1972 Stanton and Wrench partial pulverisation of crocidolite to reduce the average fibre length resulted in a reduced carcinogenic potential following intrapleural implantation. Also in 1972 Smith et al. obtained similar results using chrysotile. In 1977 Stanton et al. published some new results which confirmed the importance of fibre length, and this report suggested that only 572 fibres over IQ/u in length and less than ^u in diameter were carcinogenic. Recently we have undertaken a series of inhalation studies using rats in order to gain further information on the importance of the various dust parameters. In the first study the importance of fibre mass and fibre number was examined using the UICC standard reference samples of asbestos. Five groups of rats were treated with dust for one year following which small groups were killed at intervals to establish the levels of pulmonary fibrosis and the remainder were allowed to survive for their full lifespan, to study the development of pulmonary neoplasia. were treated with clouds of equal mass (10 mg/m crocidolite, or amosite) and since the Three groups of chrysotile, amosite fibres were found to be the largest, the chrysotile and crocidolite experiments 3 3 were duplicated at lower levels (2 mg/m and 5 mg/m respectively), at which concentrations it was estimated that the number of fibres greater than 5/i in length would be equal to that in the 3 10 mg/m amosite cloud. The lung dust content and the levels of pulmonary interstitial fibrosis and neoplasia found in these groups are shown in Table 1. Both chrysotile clouds have caused the development of more fibrosis than any of the amphibole clouds, and all the malignant pulmonary neoplasms occurred in chrysotile-treated animals. It is evident that the dust important parameter. mass is not the most These findings could be taken to indicate that chrysotile per se is the most dangerous form of asbestos, but the most likely reason for these results was found when the fibre length distribution of the dust clouds was examined in the 573 scanning electron microscope. It was found that the dust gene- ration methods used had produced clouds in which about 7% of the chrysotile fibres were over 2Qu in length but only about 0.5% of the crocidolite and amosite fibres. These results, therefore, give strong support to the suggestion that it is the long asbestos fibres that are the dangerous ones. In studies aimed at examining the importance of exposure to high levels of asbestos for short periods, the effects of this "peak" dosing were compared to those obtained for amosite and chrysotile in the previous studies, in which the dust had been administered for. 7 hours a day and 5 days each week. "peak" studies clouds of amosite at 50 mg/m 10 mg/m In and chrysotile at were administered for one day each week for comparison with the results obtained from even dosing with amosite at 10 mg/m" and chrysotile at 2 mg/m respectively. The use of the 2 mg cloud as a chrysotile base-line was necessary since it proved physically impossible to produce a chrysotile cloud of 50 mg/m of respirable dust owing to flocculation of the fibres. The levels of dust deposition and retention in the lungs following the different inhalation techniques are shown in Table 2 along with the levels of fibrosis and the number of pulmonary tumours found in the different groups of animals. It had been suggested that short periods of high intensity dust exposure might swamp the pulmonary clearance mechanism dust retention in the lung. and lead to greatly increased These figures show, however, that dust deposition during the 12 months' inhalation period and dust retention after a further six months are remarkably close. There is a slight indication of greater deposition and retention with 574 the "peak" doses but since the estimations are made on small groups of rats the differences are within the limits of experimental error. When the levels of lung pathology were examinedi however, it was found that the "peak" dusting groups showed more interstitial fibrosis in the later stages of the study than the evenly dusted animals (Fig. 1). The number of pulmonary tumours found in the two groups were close with the peak amosite animals having slightly more pulmonary adenomas than the evenly dusted amosite group and the peak chrysotile animals having slightly less than their evenly dusted counterparts. Of possibly greater importance was the fact that two malignant lung tumours were found in the peak amosite group when none had developed in the evenly dosed amosite group. No mesotheliomas were found in any animals from the "peak" dosing experiment. From these results it would appear that while"peak" dosing did not produce large changes in the resulting levels of lung pathology compared to the same dose administered over a five-day period, there were some indications of increased lung damage which were more marked with amosite than with chrysotile. The reasons for this are difficult to explain since the amount of dust found in the rat lungs at the end of the dusting period were very similar in both experiments. It is possible, however, that more of the dust from the "peak" doses had penetrated to the alveolar regions rather than being retained near to the bronchial tubes. This would be likely to result in increased levels of interstitial fibrosis. 575 In another experiment, the effects of Inhalation of heated chrysotile were examined because of worries concerning the possible hazards of the inhalation of automobile brake-lining dust. In what will probably be the first of a series of studies the chrysotile was heated to 850°C for 24 hours. Following this treatment rats were exposed for one year to a dust cloud containing 10 mg/m of this material. The length distribution of the fibres in the dust cloud was similar to that for UICC chrysotile. However, the heated chrysotile was a fragile material and the dust generation process had produced many non-fibrojs particles, so the actual fibre numbers were low (150/cm ). This study is now complete and histological examination has shown that levels of pulmonary fibrosis were too low to estimate even in the oldest animals and no pulmonary neoplasms developed in any of the group. The only indication of dust inhalation in the lungs of animals treated with heated chrysotile was clusters of dust-containing macrophages which filled a few alveoli (Fig. 2 ) . Another inhalation study on the pathological effects of different asbestos types that is in progress at the present time, involves the use of samples of chrysotile and amosite collected from the atmosphere of asbestos factories. These have been administered to groups of rats at a dose level of 10 mg/m since both samples contain ral were somewhat below this for one year although, impurities, the levels of asbestos minefigure. tion of the factory chrysotile dust The fibre length distribu- was similar to the UICC samples but the factory fibres tended to be thicker so that fibre numbers 3 per cm were lower. The factory amosite dust, however, contained more long fibres than its UICC counterpart and fibre numbers were 576 also rather higher. Only preliminary results are available from this study but while the mass of dust found in the lungs of animals at the end of the dusting period was very similar to the figures for experiments using UICC asbestos, the levels of pulmonary fibrosis were different. The factory chrysotile samples produce less early fibrosis that UICC chrysotile, but the factory amosite produced more than UICC amosite. This is further evidence that the mass of inhaled asbestos is relatively unimportant in determining levels of lung damage and the most important factors are fibre numbers and especially fibre length. 577 REFERENCES DAVIS, J.M.G. (1972) The fibrogenic effects of mineral dusts injected into the pleural cavity of mice. Brit. J. Exp. Path. ¿3, 190 - 201*. KING, E.J., CLEGG, J.W., RAE, V.M. (^6) Effect of asbestos, and of asbestos and aluminium, on the lungs of rabbits. Thorax 1, I88 - 197. KLOSTERKÖTTER, W. (1968) Experimentelle Untersuchungen über die Bedeutung der Faserlänge für die Asbest-Fibrose sowie Untersuchungen über die Beeinflussung der Fibrose durch Polyvinylpyridin-n-oxid. In:Biologische Wirkungen des Asbestos. Internationale Konferenz, Dresden. Deutsches Zentralinstitut für Arbeitsmedizin, Berlin, ¿»7 - 52. SMTTH, V.r.., mmKRT, n,n,, RAnoLLET, M , S . (1972) Biological differences in resDonse to long and short asbestos fibres. Ann. Ind. Hyg. Assoc. J. j£, A162. STANTON, H.F., LAZARD, M. < TEGjERIS, A., MILLER, E., HAY, H. and KENT, E. (1977) Carcinogenicity of fibrous glass. J. Nat. Can. Inst. ¿8, 587 - 603. STANTON, M.F., WRENCH, C. (1972) Asbestos and Fibrous Glass. Mechanisms of Mesothelioma Induction with J. Nat. Can. Inst. Jt8_, 797 - 822. TIMBRELL, V., SKIDMORE, J.W. (I968) Significance of fibre length in experimental asbestosis. Iw Biologische Wirkungen des Asbestos Internationale Konferenz, Dresden. Deutsches Zentralinstitut für Arbeitsmedizin« 52 - 56. VORWALD, A.J., DURKAN, T.M., PRATT, P.C. (1951) Experimental studies of asbestosis. A.M.A. Arch. Ind. Hyg. Occ. Med. ¿, 1 - '»J. WEBSTER, I. (1970) The pathogenesis of asbestosis. lie Pneumoconiosis, Proceedings of the International Conference, Johannesburg, 1969. Ed. H. Shapiro, Pubi. Oxford University Press, 117 - 119. WRIGHT, G.W. and KUSCHNER, M. (1975) The influence of varying fibre lengths of glass and asbestos fibres on tissue response in guinea pigs. In: Inhaled Particles IV (ed. W.H. Walton), Pergamon Press, London, Vol. Zy 455-472. 578 <\1 o VO (VI IT» E 579 VO r- o> 00 • 0» irv -» 00 •a- No. of rats in sample S 5 mg/o* VO t IM SP • Crocidolite a. s • Crocidolite 10 mg/m* • Amosite 10 mg/m* ON Chrysotile 2 mg/m* Chrysotile 10 mg/o" S Levels of interstitial fibrosis 29 mths after the start of dusting 0< Lung dust content 6 mths after the end of dusting CS Lung dust content at the end of dusting B Asbestos cloud Ol Pulmonary adenomas Bronchial carcinomas Mesotheliomas O r- o o t- S CO IM o o o s tv. VO <M T<\i s cö +> O O O vO B O VO Jj- (vT I e s. co I -*• t» ronc arci í *2 gi Al <\i o «M S I SO .23 •3 0 Ï•HSO S.H VO j - (M .» 3 +• e ^ K\• a ary as m e E rH o0 3 A» *> w o o h * 3 O *> -O •H Ov O . «M *O O o o * s O *• $ • $ OJ VO lf\ B l. •H Q O *> «> E » JO O ,505 O« a o » vo• •H O S a .e -o +• c E « vvfi « n x 3 *> +> •oc » .b0*> e e 3 O -l u l. O +> «i « tí c1 -H *• m 3 -o S S ^ S £ O c>rvi CS! O o TTK\ S IN C^ i Jf *» S SJ *> *«> 15-5 3 *• ä VU 0! S S r- ft •O C <w « 0 60*» C C « 3 o e t-l O V S ON VO VO ON T" a ^ *.-% a $ a m 11 » rH «* O -» . « . 2« " B S« gib Si** **** +»a « ti •feS rH E?ruE £ u Ko« .C «- P. o ^ C ^ *• M tu o o 4' *> M Ti E i 0) 0 O O O E UNO. |<¡ ~ 58o rH o i a o Z • -He FIGURE CAPTIONS FIG. 1 An area of interstitial fibrosis from the lungs of a rat in the "peak" amosite experiment. The animal was killed 29 months after the start of dusting. The alveolar septa are greatly thickened and within most alveolar spaces are large numbers of macrophages containing asbestos fibres. Hagr.ificatien X 250 FIO. 2 An area of lung tissue from the lungs of a rat which had Inhaled heated Chrysotil« dust for twelve months. The animal was killed 29 months after the start of dusting. The alveolar septa are normal and the only indication of dust inhalation is a cluster of macrophages containing dust which fills an alveolus which is connected to a respiratory bronchiole. Magnification X 500 581 Efectos patológicos de las nubes de amianto con fibras de distinta dimension sobre los pulmones de las ratas« J. M. G. Davis y R. E. Bolton (Reino Unido) Se trataron a grupos de ratas por inhalación de nubes de polvos procedentes de diferentes muestras de asbestos, inclusive muestras de crisotilo y de amosita de la UICC. Fueron administradas a distintas dosis, cinco días por semana durante un año y también con dosis de "punta" a muy alto nivel un día pori semana. Otros tipos de asbestos estudiados eran muestras de crisotilo y amosita recogidas directamente en las fábricas de amianto y una muestra de crisotilo recalentado durante 24 horas a las temperaturas a que están sometidas las zapatas de los frenos de automóvil. Se dispone de datos no sólo sobre los niveles de fibrosis pulmonar producida por las diferentes nubes de polvo, sino también sobre las cantidades de asbestos presentes en los pulmones de las ratas al término del perfodo de inhalación. Se dispone también de la gama completa de longitudes de las fibras para todas las nubes de polvos, calculadas tanto al microscopio óptico como al electrónico. En estudios con muestras de asbestos de la UICC se encontró que el crisotilo produce mucho más daño en los pulmones que la crocidolita o la amosita. No obstante, las cifras de longitud de las fibras muestran que las nubes de crisotilo tienen fibras mucho más largas que las de los anfiboles. Se descubrió que las dosis de "punta" causan un aumento del nivel de fibrosis intersticial en los animales más viejos, comparativamente a los otros grupos que habían recibido la misma dosis de inhalación administrada a un nivel uniforme durante toda la semana. No obstante, los niveles de polvo encontrados en los pulmones después de la aplicación de ambos métodos de aplicación de polvo eran casi idénticos. La inhalación de crisotilo recalentada producía muy 582 poca fibrosis en Codos los animales. Cuando se comprobó en las ratas una muestra de crisotilo recogida del medio ambiente de una fábrica, se descubrió que en una primera fase habCa menos fibrosis pulmonar que con el crisotilo de la UICC. Pero una muestra similar de amosita de fábrica produjo más fibrosis que la muestra correspondiente de la UICC. Estas diferencias podrían explicarse por la distribución de la longitud de las fibras en las diferentes muestras de polvo. 583 ¡3N_g_i_ç.|._5=£-§,5»I.C-|v.,\/II VII. I P.Sadoul., D.Teculescu Epreuves Fonctlonnelles dens le diagnostic orecnce et la réadaptation des Pneumoconioses VII. II L.baldonado., W.Martha Méndez., J.A.Leqapsl. , A.ronzai e«. The value of studying pulmonary function with a view to the early diagnosis of silicosis. VII. Ill K.Wilson., R.Richie., P.Stevens., Cfect of chronic amorphous silica exposure on sequential pulmonary function. VII. IV P.Garcia Herreros., G.Scano., L.Stendardi., S.Degré., R.Sergysels * A.De Coster. L'Adaptation eardiopulmanalra a L'effort chez les mineurs de charbon VII. V J.t.Diem., R.N.Jones., J.C.Gilson., H.nilndmeyer. , H.Weill The Influence of asbestos exposure on radiographic progression and functional decline a preliminary report 585 ni/i FPRFUVFS FONCTIONNELLES HAMS LE DIAHNnsTir PRECOCE ET LA READAPTATION OES PNEUMOCONIOSES P. SADOUL, D. TECIILESCU Université de Mnncv, France. A l'heure actuelle, le diannostic des pneumoconioses renose sur deux bases essentielles: les modifications radiolonioues pulmonaires et la nature des risques courus. Quelle que soit la v/aleur de la radiolonie, celle-ci ne peut être considérée comme suffisante. En effet, certai- nes pneumoconioses donnent des opacités radioloniques tres discretes, alors que l'incapacité fonctionnelle est évidente et qu'a l'examen anatomo-patholopique les lésions apparaissent non nôqliqeablBs. Il en est ainsi de l'asbestosa ou de la sidérose. Chez les mineurs de charbon les lésions ne sont pas en corrélation étroite avec les modifications radioloniques. Enfin, durant ces dernières années, il est apparu que certaines lésions parenchymateuses d'orioine professionnelle ne s'accompaqnaient pas d'anomalies radioloniques mais donnaient des troubles fonctionnels. Il en est ainsi des pneumopathies des i90cyanates (5,15). Il apparaît donc loqique de chercher des éléments de diannostic autres que radioloqiquas. Les tentatives faites pour trouver des moyens surs d'identification biologiques n'ont jusqu'ici donné aucun résultat concluant. Pour évaluer la nlace des éoreuves fonctionnelles dans le diannostic précoce dB9 pneumoconioses, il apparaît 587 utils de rapneler tout d'abord les nrandes lianes des ex-' plpratinns fonctionnelles les plus courantes puis de rechercher s'il existe un profil fonctionnel des stades infra-radioloniques dans quelques-unes des pneumoconioses les mieux étudiées jusqu'ici, nien entendu, il faudra discuter les cau- ses d'erreurs qui pourraient conduire a un diaqnostic précoce erroné. La conclusion du rappel de ces travaux sera d'évaluer ce qu'il est possible de réaliser en 1978 et de discuter les les recherches a entreprendre. 0an3 une dernière partie nous envisanerons la place des épreuves fonctionnelles dans la réadaption des pnleumdconioses. La multiplicité des examens fonctionnels proposés par les physiolooistes pousse parfois le non-spécialiste a se cantonner dans des' examens classiques qui ne sont pas hélas les plus riches d'information. On peut distinguer parmi les examens fonctionnels la mesure des volumes pulmonaires, celle des résistances et des débits, l'étude de la distribution intra-pulmonaire et enfin celle des échanges respiratoires. Ceci laisse de coté les études hômodynamiques par cathétérisme cardiaque droit ou les tests d'exercice dont la valeur pour l'évaluation de l'invalidité ou pour la réadaption n'est plus a démontrer. La frénuence des amputations de la Capacité Vitale dans les nneumoconioses débutantes est tres diversement appréciée. Pour la majorité des auteurs, la diminution n'est pas sionificative (13,16,18,19) tandis pue pour d'autres (1,8,9) un svndrnme restrictif est souvent observé. Ces discordances sont secondaires a la diversité des valeurs théoriques retenues et souvent a la mauvaise coopération des sujets examinés. La dispersion tres importante des valeurs normales comme les discordances relevées dans la littérature empêchent de retenir la seule capacité vitale comme test de depistane. 588 In ni ansi nun VE l'i S (Wnlumn rfr.ni ratoi rn max imn1/innondp) a éti lamamant nti lisi. pnrsés ( 1-"O • Tei nncort! les résultats snnt din- Cependant Rnnan ct. m i l . (17), dan? uns des pre- miaras enquêtes britanniques, notaient qua la VTFIS s'abaissait ninnifinativemBnt chnz las mineurs soumis a un important entooussiérane mais exempt de nanumoconinsa radioloniquRment décelable. Tenant compte des valeurs mnvennes observées chez plusieurs centaines de sujets comparées a celles d'un oroupe témoins, SNIDT et coll. (19) concluent qu'il existe une diminution du l/EFIS chez les mineurs exempts d'anomalies radioloniques et exposés depuis 8 ans, et plus ancore, chez les pneumoconiotiques. DECHOIIX et PIVOTEAU (5) suivant durant plusieu années un petit nroupe de mineurs avant toute modification radiolooique jusqu'à l'apparition d'imanes micronodulaires 1 observent une chute du VEI"1S de 44ml/an, valeur nettement supérie a celle tirée des normes CECA qui est dB 21 ml. Flalnré l'intérêt de ces résultats, il ne parait pas possible de retenir comme test diaqnostique le VENS car il n'est ni assez sensible ni assez spécifique. Le dispersion autour des valeurs prédi- tes n'est pas nénliqeable. La fréquence des diminutions du VENS chez les tabagiques et les bronchitiques est tres élevée. Enfin, 11 a été largement souligné que le VEMS était peu sensible a l'obstruction périphérique. Dans les pneumoconioses, la conséquence la plus précoce de l'inhalation et de la rétention des poussières est leur dépôt au niveau de la bronchiole terminale. Cet empoussiérane entraîne des lésions élémentaire bien connues : infiltration cellulaire, prolifération fibreuse et modification de calibra. Ces anomalies anatomiques peuvent retenir sur les fonctions respiratoires. La mesure des débits maximaux a différents niveaux de la capacité vitale permettrait de mieux connaître l'état des petites voies aériennes (2). LAPP et SEATON ont trouvé une diminution du débit maximal a 50% de la capacité vitale chez des mineurs sans perturbation spironraphique (11). 589 I.'aiinmentati.on Hu Volume Résiduel, observée par MORGAN p.t cnll. 'l?) cho7 lp.n mineurs avec ou sans nneumnconiose simple, n'avant ni abaissement du VEfS/CW, ni antécédent tabaniA nun, p-.h nnut. PA.TR imputable a cos lisions distales. Cette hvnothfîpR est confirmée par 1 R S mesures de compliance dynami— nue effectuées en ventilation spontanée ou a différentes fréquences, ou encore oar des mesures plus complexes (il). Les examens mettent en évidence les altérations da la distensibilité pulmonaire et 1'inhnmonénéité du poumon empoussiéré secondaire a l'obstruction des petites unies aérienne. Toutefois les mesures de compliances ne sont pas aisément praticables en mutina pt les aunmentations du volume résiduel sinnificatives, pour un oroune do sujets, ne sont pas asse7 marquées au stade radinlonique de détectinn précoce. pour être retenues comme test L'élévation du volume résiduel n'est d'ailleurs pas retrouvée avec les techniques de dilution(l9). L'étude des troubles de distribution aérienne ou mixique peut être faite au cours d'une ventilation calme ou sur un seul cycle ventilatoire. Les techniques en ranime stable montrent fréquemment de3 anomalies alors qu'il n'existe pas ennorB de pneumnconiosB radioloqiquement décelable (19 ,2P). Cependant, la variabilité de3 résultats avec le réqime ventilatoire comme la multiplicité des indices choisis les ont fait abandonner pour les tests d'inspiration unique qui, propqsés il y a 3D ans par CDPIROE et FOULLER, ont joui d'une grande faveur durant ces dernières années. La mesure du volume de fermeture a été larnement utilisée pour détecter précocement l'obstruction des bronches distales. Le transfert du CO étudié en réoime stable décelé souvent les anomalies. PH/OTEAII et OECHOUX le trouvent perturbé dans plus d' un cas sur deux chez des mineurs porteurs d'opacités 59o micronodulaires, alors nue le test en aonée ne l'est que rarement (14*). Les résultats do la mesure en ranime sta- ble dépendent larnement des troubler, de distribution aérienne (16). Le transfert du Hfl en apnée neut être perturbé précocement dans l'asbestose mais cette anomalie, souvent retrouvée dans les formes avancées (l) t ne peut constituer un sinne prénoce (8). TRANS et coll. montrent (7) nu'entre oenumnconiotiques débutants et témoins, seul le volume sannuin capillaire pulmonaire est sionificativement différent, Uns des perturbations 1 B 9 plus fréquentes, révélées par 1 R S investioations détaillées, est l'auomentation du nradient alvôolo-artériel d'oxypène (19) et 2 2 ) . Malheu- reusement, sa mesure exioe un prélèvement de sano et mesures rinoureuses;de plus, la reproductibilité de ce oradient n'est pas excellente. EXAHENT UTILISABLES DANS LE DEPISTAGE PRECOCE Au total, parmi les tres nombreuses techniques d'études des fonctions respiratoires pulmonaires,il convient de sélectionner celles qui sont utilisées pour le diaqnostic précoce des pneumoconioses. Les conditions que doivent rem- plir les tests retenus pour les enauetes épiriémiolooiques, ont été précisées par de nombreuses réunions, en particulier celles organisée en 1973 par le National Heart and Luno Institute (21) : IB) Validité î le test ôvalue-t-il les perturbations susceptibles d'apparaître dans la maladie considérée? 591 2 9 ' Sensibili t_é: Huells est la prooortion de sujets attnints riécelée nar le test? 39) qpijcifité: n uelle est la proportion rie sujets sains identifiers oar l'examen?' 4S ) Precision : Le test donne-t-il le mame résultat quand il e3t appliqué de façon répétée dans des conditions nnrnparah.1es, 59) Acceptabilité : L'absence de caractère traumatisant le rend acceptable oar la population a examinar. 65) Faisabilité : Est-il applicable sans difficulté majeure a un nombre élevé de sujets (technique simple et rapide)?. 70) Coût; Fst-il proportionné au bénéfice obtenu? Quoique la mesure dB la capacité vitale et du VEPIS soit considérée par beaucoup d'auteurs comme répondant a toutes ces conditions, les recherches faites sous l'éoide de la Communauté européenne du Charbon et de l'Acier, les résultats publiés dans la littérature montrent que la préoisinn des mesures diffère larnement suivant l'habileté du technicien et la coopération du sujet. L'examen attentif du soirooramme est indispensable pour vérifier la validité des mesures. Les mêmes remarques peuvent être formulées pour tnutes les épreuves utilisant une mesure des volumes et des débits maximaux en particulier les boucles débitvolume. L'intérêt des débits maximaux a 5055 et à 2à% de la caoacité vitale est indiscutable, toutefois pour la dernière mesure il existe une disoersion non néqlineable des résultats. 592 l.es risili tats' rt' autres mesures sont ranina dépendantes H B la coopération du sujet; il en est ainsi ries techniques étudiant la mixinue. La pente d'azote nu partie 3 do la cnurbe est maintenant préférée, a juste titre, a la détermination précise du volume de fermeture. Le test do transfert du CD en ranime stable a l'avantaoe de constituer un index global puisqu'il reflète non seulement la qualité des échanqes respiratoires, mais aussi la mixioue. Si 1'nn nrend la précaution ri'enrenistrer le spirorramme pendant la mesure et d'étalonner l'appareil sur l'air expiré par le sujet, on obtient facilement des mesures reproductibles. Puisque de discrets troubles des échannes snnt l'une des premieres manifestations des penumoconioses, cet examen devrait être plus snuvent utilisé. Compte tenu du fait que les valeurs prédites restent toujours quelque peu imprécises, la détection précoce sera plus fiable si des mesures fonctionnelles respiratoires ont été pratiquées avant l'exposition aux risques pneumoconiotiques. Il est souhaitable que le sujet soit en quoique sorte son propre témoin. En l'abscence de ces mesures d'em- bauché, les premieres anomalies risquent de passer inaperpues. RECHERCHES A ENTREPRENDRE Pour préciser les anomalies les plus précoces, secondaires aux pneumoconioses, il apparait indispensable de multiplier les enquêtes épidémiolooiques longitudinales. Certes plusieurs équipes en ont pratiqué, mais mis a part les mineurs de charbon, le nombre de sujets soumis a ces enquêtes reste modeste et le recul ne dépasse pas quelques années. Il serait souhaitable que certaines de ces enquêtes lnnoitudinalB3 soient effectuées an utilisant des tests multiples 593 explorant différentes fonctions élémentaires pulmonaires. Oe telles recherches permettraient de préciser quels sont les examens les plus sensibles. De telles enquêtes prospectives sont indispensables dans les industries utilisant de nouveaux procédés de fabrication. Files devraient être entreprises des qu'une aug- mentation de la fréquence des infections pulmonaires ou de phénomènesdyspnôiquea a été notée par le médecin du travail. Si des procédés de fabrication nocifs ou des substances toxiques sont utilisés, de tallas anquetas épidémiolooiques devraient être systématiques afin d'identifier des bronchopneumonathies professionnelles encore inconnues. Une enquê- te faite dans une usine utilisant les isocyanates, ou les ouvriers n'avaient aucune doléance, montre bien la nécessité de telles investiaations (15). EXPLORATION FONCTIONNELLES RESPIRATOIRES ET READAPTATION DES JJNE. U.^£0_NJ£TJU]JJEJ3 Si la place exacte des épreuves fonctionnelles dans le diapnostic précoce des pneumoconioses dépend encore du résultat des recherches a entreprendre, il n'en est pas de même en ce qui concerne la réadaptation. Qu'il s'aqisse de réentrainement a l'exercice ou d'affection dVinpneumoconiotique handicapé a un nouveau poste, le bilan préalable fait nécessairement appBl aux éoreuves fonctionnelles. S'il n r en est nas ainsi, de nraves mécomptes seront rencontrés en metieres de réadaptation. Pour évaluer l'aptitude d'un ouvrier a un nouveau noste de travail, il est indispensable d'évaluer son déficit fonctionnel respiratoire. Los éprmivss de repos ne nnnt pas alors suffinant.es, il faut recourir A dna tests d'exercice. I.'énreuve triannulairn nronosée par la Communauté européenne 59* du Charbon et de l'Acier il « a tifi ja 1? ans, avec nunmentatinn rie la charno rie 30-U nhanue 3 minutes, est narticul i T 9 nnnt satisfaisante (23). Elle rinnne dos résultats nratinue- mont aussi fidèles que les énrauves rraotannulaires répétées qui permettent le calcul rie la Puissance Maximale Supportée (fi). Par contre, les déterminations baseras uniquement sur la fréquence cardiaque donnent rie nraves mécomptes che? les pneumnconiotiques et ne sauraient être retenues. De memn les exercices sous maximaux risquent de conduire a des conclusions trop optimistes. Le recours au cathétërisme cardiaque droit ne nnut nuere être envisaqé comme épreuves de routine. Il donne des informations extrêmement satisfaisantes si les nrnssions mesurées dans la petite circulation sont confrontées avec le débit cardiaque et les naz riu sang, au repos comme au coui9 d'un exercice. La rééducation respiratoire et le réentrainement au travail donneront dBS résultats d'autant plus satisfaisants qu'il existe un élément réversible, c'est-a-dire des manifestations bronchitiques. En effet, on ne peut espérer améliorer l'état du parenchyme ou réduire les lésions vasculaires par une physiothérapie aussi bien conduite soit-elle. Cependant, a un stade avancé de la maladie, la rééducation et le réentrainement au travail donnent un confort aux pneumoooniotiques qui leur permet d'utiliser leurs réserves respiratoires diminuées. Les résultats obtenus par la rééducation respiratoire ne sont certes pas nénlineables, mais ils ne doivent pas faire oublier que les x premieres mesures à prendre dans les pneumoconioses sont une prévention efficace et celle-ci ne peut être 595 e n t r e n r i rçn nun >Îi n<">us s a i n i s s n n s de façon t r e n nrilcnce n r n n i i n r n s m a n i f e s t a t i o n s des nneumnoonioses. C'est pourquoi 1R9 i n r n t i v e s f n n r t i n n n G l l e s comme moyen de d i a g n o s t i c coco de eos m a l a d i e s d o i v e n t f a i r e ri'investioatinns s " s t i m a t i ni l e s . 596 les oré- l ' o b j e t de r e c h e r c h e s et Pruebas funcionales en el dlagnótlco precoz v la readaptacíón de las neumocontosis Informe Introductorio por P. Sadoul, D. Teculescu (Francia) El diagnóstico de las neumoconlosls se basa actualmente en la radiografía y la naturaleza de los riesgos sufridos i las pruebas funcionales respiratorias se utilizan normalmente para la evaluación de la Invalidez. La utilización de pruebas funcionales para el diagnóstico precoz de las neumoconiosls no ha sido objeto de Investigaciones sistemáticas ni de confrontaciones análogas a las que han tenido lugar para la radiografía. Numerosos factores entorpecen las tentativas en esta esferai la frecuencia de las afecciones broncopulmonares extraprofeslonales, particularmente las vinculadas al tabaquismo, la escasez de estudios longitudinales en obreros sometidos a riesgos neumoconlótlcos, la falta de especificidad de las perturbaciones funcionales, las lncertldumbres Inherentes a los valores de referencia, etc. Las encuestas epidemiológicas efectuadas con trabajadores expuestos han demostrado que los Individuos sin anomalía radiológica presaltaban perturbaciones de que carecían los pacientes de muestra. De todos modos, estas anomalías no quedan siempre puestas en evidencia por las pruebas esplrográflcas clásicas, sino que son reveladas a menudo por la exploración de los Intercambios. Las diversas neumoconlosls no crean perturbaciones funcionales de Igual tipo. En la neumoconlosls de los mineros del carbón es bastante frecuente un síndrome obstructivo, Imposible de disociar del de la bronquitis banal. En las silicosis puras la hipertensión arterial pulmonar puede ser relativamente precoz. En la asbestosls, las perturbaciones de los Intercambios pueden 597 preceder a cualquier otra anomalía. Además» un mismo riesgo puede acarrear modificaciones funcionales muy diferentes de un individuo a otro. En la medicina del trabajo no es posible recurrir a pruebas traumatizantes o caras. Es preciso respetar los criterios de selección adoptados por los epidemiólogos. Las pruebas funcionales sólo constituyen actualmente un elemento de apoyo para la obtención de un diagnóstico. Sólo investigaciones sistemáticas de tipo prospectivo permitirán concluir si aquéllas desempeñarán en el futuro un papel tan importante como el de la radiología. La readaptación de los neumoconióticos es una tarea dificil. Las pruebas funcionales respiratorias desempeñan un papel esencial en la selección de los obreros enfermos. La gravedad de ciertas perturbaciones vinculadas a lesiones anatómicas irreversibles impide un reentrenamiento físico. La evolutividad, siempre difiel de prever, puede hacer inútiles los esfuerzos realizados. Por el contrario, la readaptación está muy indicada en determinados obreros que padecen bronquitis de acompañamiento o bien una neuraoconiosis no evolutiva. 598 EL VALOR DE LAS PRUEBAS DE FUNCIONAMIENTO PULMONAR EN EL DIAGNOSTICO OPORTUNO DE LA SILICOSIS. ... It 1s argued that... disabling silicosis can only exist where "nodulation" is present 1n the x-ray picture, then 1t 1s possible, and even likely, that workers may unjustly be denied compensation 1 . Greenburg.L. ,1972 * * * ** Dr. L. Maldonado T., Dra. M. M. Méndez V. , Dr. J. A. Legaspl V. y Dra. A. González Z. I N T R O D U C C I Ó N En México, los padecimientos broncopulmonares ocupan el primer lugar dentro de las enfermedades consideradas como de 2 4 trabajo, puesto que constituyen casi el 80% ' . Dentro de es^ tos padecimientos broncopulmonares, los más frecuentes son las neumocon1os1s, ocupan el 90S 3 * 4 y de estas neumocon1os1s alre_ dedor del 60 al 65%, *•* son producidas por mezclas de sílice y silicatos, a excepción del asbesto. Cuando en 1973, propusimos * en el Instituto Mexicano del Seguro S o d a i , que: "para establecer el diagnostico de neu^ moconiosls es Indispensable que coexistan el antecedente de ex. posición a ambiente polvoso (o con humos y algunas nieblas) y las alteraciones radiográficas compatibles con el p a d e c i m i e n to, pudlendo o nó encontrar datos clínicos"; consideramos como * Jefatura de Medicina del Trabajo. ** Hospital de Cardiología y Neumologfa. Centro Médico Nacional, Instituto Mexicano del Seguro Social México, D. F., MEXICO. 599 compatibles únicamente las opacidades redondeadas característl cas y se recomendó clasificarlas siguiendo las pautas de la -Clasificación Internacional de Radiografías de Neumoconlosls (Revisada, 1968), Corta, de la O.I.T., con un criterio conservador estricto; aunque algunos de los Integrantes del Grupo de Estudio de Enfermedades Broncopulmonares de Trabajo, que establecimos los requisitos, en la Institución mencionada, o p i n a mos, desde entonces, que se deberían considerar también las -opacidades irregulares, usando la Ampliada, con un criterio -más abierto; solo que predominó el anterior. S1n embargo, para aprovechar que nos eran enviados desde esa época, trabajado, res expuestos sobre todo a la Inhalación de partículas de mezclas de polvos de sílice y silicatos, en quienes se tenía la sospecha o se hacía la reclamación, por el mismo trabajador, el sindicato o el patrón, de que padecían silicosis y solicita. ban la compensación y de que muchos de ellos presentaban única, mente opacidades Irregulares, en su radiografía de tórax, é s tos se estudiaron de la misma manera que los que tenían opacidades redondeadas. Es decir, todo trabajador expuesto a m e z clas de polvos de sílice y silicatos, con opacidades redondeadas o Irregulares, en su radiografía del tórax, se estudió de manera similar y se clasificaron las opacidades de acuerdo a la Clasificación Internacional de Radiografías de Neumoconlo— sis U/C, 1971, Corta, de la O.I.T.; en la que se anota que ad£ más de en la asbestosls, se observan radiografías con opacidades Irregulares pequeñas también en la silicosis, la neumoconlosls por polvos mixtos, etc.. En cada uno de ellos, se hizo Interrogatorio y exploración física, se midieron la estatura y el peso, la hemoglobina, el hematocrito, los leucocitos y la fórmula diferencial; se hiele, ron reacción de Mantoux, baclloscopías y cultivos, en serle de tres días, si el trabajador presentaba expectoración así como telerradiografías de tórax en póstero anterior, en Inspiración y espiración forzadas, oblicuas anteriores, derecha a Izquier- 600 da, estudio electrocardiografía y pruebas de funcionamiento pulmonar. Aparte, para completar el estudio, en algunos ca- sos, otros exámenes de laboratorio, según se requiriera. MATERIAL Y METODO Para este estudio, se seleccionaron los expedientes en -los cuales las radiografías de tórax mostraran opacidades 1rre_ guiares pequeñas, en el orden en que estaban archivados y se desecharon los demás, hasta reunir 500 expedientes. De estos se obtuvieron datos tales como número secuenclal, datos para identificar al trabajador, sexo, edad, lugar de nacimiento, empresa, puesto, antigüedad, tabaquismo, patolo_ gfa pulmonar previa, síntomas, estatura, peso, frecuencias re£ plratorla y cardiaca, signos, síndromes, cifras de: hemoglobina, h e m a t o c H t o , leucocitos y formula diferencial, resultados de la prueba de Mantoux, de las baclloscopías y de los c u l t i vos, las radiografías se clasificaron de acuerdo con el código de la Clasificación Internacional de Radiografías de Neumoco-niosls, 1971, UIC/UC, Corta, de la O.I.T., las alteraciones -electrocardiografías y los resultados en cifras de la capacidad vital, de la velocidad de flujo máximo espiratorio, de la velocidad de flujo medio espiratorio, de la presión alveolar de oxígeno, de la presión alveolar de dióxido de carbono, del pH, de la relación e s p a d o muerto/aire corriente y de la existencia de cortos circuitos, correspondientes a las pruebas de funcionamiento pulmonar y su correlación con respecto al estado de la mecánica respiratoria, ventilación e Intercambio g a seoso. R E S U L T A D O S La mayoría de los trabajadores seleccionados fueron bres, 470 (94«) y 30,(6Ï) mujeres. hom- La edad varió entre 16 y 80 años; la gran mayoría se en-- 6o1 contro entre 26 y 60 años (463; 92.6%); entre 16 y 25 (11; 2.2«) y entre 61 y 80 (26; 5.2%). El lugar de nacimiento permitió verificar que ninguno fue_ ra originarlo de una zona minera. Las empresas y los puestos en que trabajaron, correspon-den en la casi totalidad (388; 77.6%) a fábricas en que se eia, bora porcelana, semlporcelana y loza; (93; 18.6%) a una fábrica de tabiques refractarlos y el resto (19; 3.8%), a diferen-tes empresas generadoras de polvo de mezclas de sílice y silicatos. La antigüedad de la exposición fue en la mayoría de 10 a 30 años (439; 87.5%), pard algunos de 31 a 45 años (44; 8.8%) y para la minoría de 3 a 5 años (16; 3.2%). El tabaquismo se encontró negativo en 159 (31.8%); de 1 a 5 cigarrillos, en 227 (45.4%), de 6 a 10 cigarrillos, en 73 -(14.6%) y de 11 a 20 cigarrillos, en 27 (5.4%) y de más de 20 cigarrillos en 14 (2.8%), en 24 horas. La duración fue de 1 a 55 años. Sólo en 3 casos se encontró patología pulmonar previa - (0.6%), provocada por tuberculosis pulmonar. En 182 (36.4%), no se encontró sintomatologia del aparato respiratorio, 41 (8.2%) presentaron disnea de esfuerzo y 277 (55.4%) síntomas de bronquitis. De estos 85 nunca habían fuiM do (17%) y 192 (38.4%) SÍ. En (377; 75.4%) se encontraron dentro del peso normal y (133; 24.6Ï) fueron obesos. Grado 1-103 (20.6%). Grado II- 28 (5.6%) y Grado III-2 (0.4%). La exploración de tórax fue en casi todos negativa, pero en 5 (1%) se encontró síndrome de condensación. La hemoglobina y el hematocrito fueron normales en 450 -(90%), se encontraron disminuidos en 3 (0.6%) y hemoconcentra- 6o2 clon en 42 (8.4%). Tanto los leucocitos como la fórmula diferencial se encoja traron normales en 200 (40%), hubo Hnfoc1tos1s en 237 (47.4%), eosinofilia en 26 (5.2%) y Hnfoc1tos1s y eosinofilia en 15 -(3%). El Mantoux fue positivo en 285 (57%) y negativo en 153 -(30.6%). Las badloscopfas para BAAR fueron negativas en 200 (40%). Las opacidades Irregulares en las radiografías de tórax fueron finas 1, en 4 (0.2%); finas 2, en 11 (2.2%); finas 3 en 210 (42%); en total finas en 225 (45%); medianas 1, en 9 (1.8%); medianas 2, en 22 (4.4%); medianas 3, en 196 (39.2%); en total medianas en 227 (45.4%); gruesas 1, en 0 (0%); g r u e sas 2, en 3 (0.6%) y gruesas 3, en 45 (9%); en total gruesas en 48 (9.6%). No se tomo electrocardiograma en 397 (79.4%). En 49 - (9.8%) se encontró dentro de limites normales y en 29 (5.8%) se observó crecimiento de cavidades Izquierdas en 16 (3.2%), de cavidades derechas en 16 (3.2%) y crecimiento de cavidades derechas e Izquierdas en 9 (1.8%). Los resultados de las pruebas de funcionamiento pulmonar se encontraron normales en 109 (21.8%) y, en el resto, se e n contró: restricción en 28 (5.6%), obstrucción bronquial cen- trai en 4 (0.8%), obstrucción bronquial periférica en 78 (15.6%); hlpoxemla en 56 (11.2%) y combinaciones de las a n t e riores en 225 (45%). Cuadro I . C O M E N T A R I O Trabajan más hombres que mujeres en la Industria, por lo que los datos encontrados de mayor nomerò de hombres, nó son de extrañar. 6o3 La edad concuerda con la de la época productiva (25 a 60 años); algunos segufan trabajando despues de la edad de jubila^ ción, aparentemente en buenas condiciones. No encontramos en ninguno el antecedente de haber sido mj_ nero. Esto es Importante puesto que generalmente lo niegan en el Interrogatorio, debido a que atribuyen su patología a la -contaminación del medio ambiente de la ocupación actual y buscan nueva compensación. El que la mayoría hayan trabajado en fábricas de cerámica se debe a que estudiamos principalmente trabajadores de las 1r^ dustrlas de transformación y muy pocos de la de extracción, -ya que el aseguramiento de mineros se Inició a partir de 1972. La gran mayoría de los casos estudiados, estuvieron ex- puestos por tiempo suficiente a las partículas del polvo dañino. En general, no se observó patología pulmonar previa que hubiera dejado secuelas que se reflejaran en el estudio func1o_ nal, excepto en un caso de toracotomía. Es de esperarse que en algunos no exista cuadro clínico, que otros presenten disnea y que algunos refieran síntomas de bronquitis, Incluyendo los nó fumadores, con el antecedente de hasta 20 años de exposición al polvo. En los obesos las alteraciones en los resultados de las pruebas de función respiratoria son atribulóles parcialmente al sobrepeso. En los que se encontró patología pulmonar previa y ésta obviamente contribuye a la alteración funcional. En los casos de hemoconcentraclón, esta es significativa, en ausencia de opacidades redondeadas. La llnfodtosls y la eosinofilia, solas o combinadas, no es f S d l su explicación, sin embargo, son un hallazgo frecuente en las neumoconlosls. 6o4 El Mantoux positivo, como Indicio de la pr1mo1nfecc1ön tu_ berculosa, es significante, porque sus secuelas, aún las nó vi slbles radiográficamente pueden dar lugar a alteración funcional . No encontramos correlación entre opacidades Irregulares de tipos finas, medias y gruesas, n1 de profusión 1, 2 y 3 con el grado de alteración funcional. C O N C L U S I O N E S En la práctica vemos que por lo menos en algunos casos -las opacidades Irregulares pequeñas coinciden con opacidades redondeadas o evolucionan a ellas. Es por tanto importante que se estudien de la misma manera los trabajadores que presenten radiografías con opacidades Irregulares pequeñas que los que presenten opacidades redondea, das pequeñas. Se considera que por lo menos en los nó fumadores, las ai t e r a d o n e s funcionales deben atribuirse a las opacidades irregulares pequeñas. Además, es muy probable que estas o p a c i d a des representen el estadio Inicial de este tipo de neumoconlos1s. R E F E R E N C I A S 1.- Greenburg, L.: The classification of dusts which cause pulmonary disability. Journal of Occupational Medicine 14: 146-148, 1972. 2.- González, Z., A., Maldonado T., L., Sepûlveda L., D. y Rodriguez R., D.: Neumopatfa laborales no traumáticas. Valoración del grado de Incapacidad. Criterios clínico, 6o5 radiologico y funcional. Patología Laboral, Fascículo -13, Volumen V, Anuario de Actualización en Medicina. I.M.S.S., 1973, Págs. 37-43. 3.- Maldonado T., L.: Las enfermedades de trabajo mas frecuen. tes en México. Condiciones de Trabajo. Vol. 2. No. 2. -Mayo-Agosto, 1977. Págs. 103-104. 4.- Maldonado T., L.: Estadística sobre enfermedades de traba, jo en México, en 1977; aún no publicada. 5.- González Z., A., García P., E., González Q., E., Landini C , R., Maldonado T. , L. y Montoya C , M. A.: Normas para el diagnostico, tratamiento y profilaxis del trabajador expuesto a Inhalación de polvos Inorgánicos. Edición en fotocopia. Departamento de Riesgos de Trabajo y Hospital de Enfermedades del Tórax, en el Centro Médico Nacional, de la Subdlrecdön General Médica, del Instituto Mexicano del Seguro Social, Noviembre de 1973. 6.- González Z., A., García P., E., González Q., E., Landini C , R., Maldonado T., L. y Montoya C , M. A.: Diagnóstico, tratamiento y profilaxis de las enfermedades provocadas por la Inhalación de polvos Inorgánicos. Boletín Médico, I.M.S.S. Vol. 16. Nûm. 7. Julio, 1974. Págs. 258-267. 7.- ILO U/C International Classification of radiographs of -pneumoconioses 1971. Occupational Safety and Health Series 22 (rev.), International Labour Office, Geneva, Switzerland, 1972, Pág. 22. 606 Ol os n o r— io o CM CM CM se 00 LU o m o a p< •a k •M C ai u s z i _l 3 a. < l- o _i i z <s> U l U l •—1 ce => V) o _i Ul o 5 z o »H o z = u. z o V) ai ^•a 1— 1 - 3 er c o i. J3 3 er c o k XI 3 cr c o k XI C <o C IO c >» «O O ai o « Ü 3 k 4-> VI XI O Ol X •a •r- S ai X o a. •»- « ai «O «O •^ o x: a. ai Ol C ai o ^- t. «ai Mk ai CL OL >> ^10 C ai u k XI c «J *> •*o» •^ u u 3 V. cr c o 1— o u 3 k +> VI <VI-» O XI O XI o «O c >o •»•> >> Q O O O O O u u o o u o k k k k k k 4J VI 4J VI +J VI 4-> V> •»-> VI +•» VI IO o •e k <ai 14•rk ai a. E 0) X o o. •rx: k •!-> c' IO VI XI r- •a u i— t. <0) •*i— k ai CL ' C u 3 k r-* o 1 " er c o k XI IO LO ^- u er e o u u 3 k CM • ^ »IO~ ^•0 *— •3 •^ •^ 3 3 1 - « oo CM r- r— IO o XI f >l ai X o a. x: ai u • ^ +» «X rUl k ai a. ^10 VI XI O u 1 - •^ U e ^IO »— k 10 k *> c 4-> ^— 10 U o 3 k •V— >» •^ k «u <»t— <o • ^ E U o c ce. CL ce IO •^ IO u o» r*. P-* k 101 «fik ai a. o o «t _1 CM CO VI i- ik «I >) 0) i- p- 10 E Ol u X k o CL <ai >^> i— <*x: ai O 1L io •*- io io %ai i. +J C i4-1 C t*> C tk 01 k ai CL tik ai a. ai ai ai o10 1— 10 o 10 o 10 o. IO i- 3 1 - 1 - 1 - 1 - 3 CT 3 3 3 3 k XI XI k XI k XI k XI c c c c c o o «) * o c « cr c er er cr cr e o e e e e o k o o o o k X) O i— IO i— i— *^ i— "^ i— 10 O i - U O O O O O i o O E O C J O O O O E k 1 - 0 1 3 3 3 3 3 3 0 1 k X k k k k k k X +J 4J04J4->4->4-»4->4-> O VI V I C L V I V I V I V I V I V I Q . oí O l i - XI X) XI XI XI XI i - ai oí ai ai ai ai ce oc oc ce oc oc et ocx: o 6o7 o o o o o a: 10 4-> o The value of studying pulmonary function with a view to the early dla^noslB of alíjeosle li. Maldonado T.. M. Martha Mènde a 7., J.A. Legaspi V,. A. González Z. (Mexico) As a general rule, sllioosis develop« asymptomatically, at least in ite initial stages, so that in studying it one cannot expeot X-rays to show the oharaoteristio epeokled pattern formed by small round opacities in X-ray photographs taken of workers who have been exposed for a sufficiently long time to particles of silica and silicate dust, but the examination has to he undertaken when small irregular opacities are already to be observed, in the same manner as in the previous oase. by means of olinloal study, laboratory tests, radiographic and eleotro-oardiographlo examination and pulmonary funotioni teats. This manner of prooeeding has «any advantages in day-today praotioe as it enables a high percentage of early alterations to be deteoted. In the majority of cassa there are signs of pulmonary restriction, medical or peripheral bronchial obstruction, hypoxemia or hyperoapnia, alón« or in combination. Only in a small percentage of oases are the results of the pulmonary function tests nonni, despite initial radiographic evidenoe of lung disease* Although unfortunately the majority of workers in our oountry oontlnue to work in the saae unsatisfactory condition«, this s'mdy may serve as a basis for their protection. And, in the oase of the luokier ones, it may save them from exposure. 608 EFFECT OF CHRONIC AMORPHOUS SILICA EXPOSURE ON SEQUENTIAL PULMONARY FUNCTION K. Wilson, R. Richie, P. Stevens Braes Valley, Houston, Texas, United States Although the flbrogenlc effect of crystalline silica on the lungs is well known, amorphous silica is reported to be relatively harmless in both animal and human studies. However, previous workers have reported pulmonary fibrosis in workers exposed to calcined diatomite known to contain crystalline silica, and Vitums has re- cently reported pulmonary fibrosis in 11 of 40 workers exposed to fumed amorphous silica. Because there are several different pro- duction methods of amorphous silica, the potential toxic effects may vary. We have studied retrospectively the chest radiographs, serial spirograms, and screening respiratory questionnaires of a group of workers exposed to precipitated amorphous silica. Precipitated amorphous silica Is produced by subjecting a sand and alkali solution to heat to form sodium silicate in solutioni Amorphous silica is then precipitated from solution by adding CO2 or CaCl2< The resulting product has no crystalline silica detectable by x-ray crystallography. Particle size varies depending on the production method from submicron to micron size, all within the respirable range. The study population consisted of 165 male workers with a mean age of 42 years. The only requirement for inclusion in the 6o9 study was that the workers have at least one year of precipitated amorphous silica (PAS) exposure so that serial radiographs and spirograms would be available. Chest radiographs and spirograms using variably a Collins Water seal. Donti electronic, or Vitalor spirometer have been obtained on all PAS workers on beginning employment and yearly thereafter for the last 10 years. Respiratory screening questionnaires modified from the British Medical Research Council format were completed by all workers during the last year. Chest radiographe wetre reviewed independently by two experienced chest physicians and a radiologist, and classified for pneumoconiosis using the UlCC/Cincinnati criteria. Spirographic data obtained from each tracing included forced vital capacity, forced expired volume in one second, and maximum mid-flow or FEF25-75. Each tracing was reduced by an experienced pulmonary function technician. Change in pulmonary function variable per year was obtained by subtracting final from initial value and dividing by years between the tests. The extent of each worker's exposure to PAS was expressed so as to reflect both the quantity and duration of exposure. The cumulative exposure index, reflecting total PAS exposure, was calculated for each worker by multiplying months of exposure times relative concentration of atmospheric dust in his work area. Dust concentration was measured by personal airspace gravimetric monitoring and graded on a scale of 1 (minimal) to 4 (extensive). 61o The mean exposure Index Indicates average monthly exposure for workers with variable exposure, and was calculated by dividing the cumulative exposure index by total months of exposure. The relationship between yearly change In forced vital capacity and cumulative exposure index was evaluated by linear regression analysis. As seen here, with an R value of 0.1, there was no correlation between these variables. Using similar analysis, no correlation was found between yearly change In FEV1 and cumulative exposure or yearly change of FEF25-75 and cumulative exposure. To avoid possible masking of an effect of increasing exposure, the overall group was divided into four subgroups with Increasing exposure. There was no statistical difference between yearly change in any pulmonary function variable and Increasing exposure. To evaluate possible latency of PAS effect, the relationship between yearly change of FVC and total years of exposure was examined with linear regression analysis. With an R value of 0.13, there was no correlation between total years of exposure and decrement In FVC. Similarly, there was no correlation between yearly change in FEV1, and total years of exposure or between yearly change of FEF25-75 and total years of exposure. 611 Further to evaluate the effects of total time of exposure on pulmonary function, a group of 44 workers exposed for 11-35 years with a mean exposure time of 18 years was compared to workers with less than 10 years exposuret Again, there was no difference in yearly change of FVC or FEV1 between the two groups« There was no relationship between mean exposure index and clinical symtoms of coughi sputum production, wheezing or dyspnea. However, there was an interesting inverse relationship between cumulative exposure index and both sputum production and dyspnea. Workers with these symptoms had statistically less exposure than those without symptoms, raising the interesting but unproven hypothesis that symptomatic workers may drop out of this type work. Symptoms of cough,and dyspnea, but not sputum production, were statistically more common in heavier smokers. Additionally, and not surprisingly, all symptoms but dyspnea were more common among smokers than among non-smokers. Of the 143 workers with chest radiographs prior to PAS exposure and during the past year for comparison, 11 (7.5%) had radiographic change consistent with 1/1 or 1/0 small rounded p or small irregular t-type opacities. All 11 workers had a previous history of working in a local limestone mine or in a soda ash plant using crushed limestone. No workers with up to 35 years exposure and a work history of exposure only to PAS had any evidence of pneumoconiosis. CONCLUSIONI No relationship was found between yearly change in 612 pulmonary function parameters and either quantity of or duration of exposure to PAS. There was no radiographic evidence of pneumoconiosis In workers exposed only to PAS. Symptoms had no relationship to or correlated Inversely with PAS exposure, but symptoms were directly related to cigarette smoking. 613 VII/4 L'ADAPTATION CARDIOPIILdOMATRe CHEZ I F S A L'EFFORT NTNFJ.mS OF CHARRON P. GARCIA-HERREROS, C. SCANO, L. STENDARDI, S. DEGRE, R. SERGYSELS 4 A. DE COSTER. Hospital Universitaire Saint-Pierre, Bruxelles, Bitloique. L'évaluation fonctionnelle au repos et pendant l'exercice ds3 patients atteints d'anthracosilicose (AS) est souvent difficile car cette patholooie est souvent associée a une bronchopneumopathie chronique obstructive ispeo) qui ne permet pas de faire clairement la distinction entre lea altérations dues a la pneumoconiose pure et les maladies surajoutées. Pour ce travail, nous avons' étudié la fonction i pulmonaire et l'adaptation cardio-pulmonaire a l'effort chez 26 mineurs sans siqnes évidents cliniques et/ou fonctionnels de BPCO associée. 615 PATIEMTS ET METHODES l e r e diapositive Les 26 mineurs ont été répartis en 3 groupes d'après les critères radioloqiques du B.I.T. (classification, 1971). Le premier qroupe (c) ou groupé controle se compose de 8 mineurs sans signes radioloqiques de pneumoconiose. Le deuxième aroupe (Si) comporte 10 patients dont l'image radiolooique varie entre P3 et q(m)3. Le troisième groupe (S2) se compose de 8 mineurs au stade pseudotumors! : A, 8 et C. Il n'y a paa de différence nette d'âge moyen pour les trois groupes. Tous les patients ont subi un bilan fonctionnel respiratoire au repos comportant la mesure dea volumes pulmonaires et la capacità de diffusion au CO en apnée inspiratole. Ils ont également effectua une épreuve d'effort par paliers en position assise 9ur cycloergometre. Les paliers maintenus environ 6 minutes ont été réalisés aux charqes de 250 et 400 Kqm.min* '. les paramètres suivants ont été mesurés: la ventilation (VE), la consommation d'02 (V02), les gaz du sann artériel (Pa02, PaC02, pP, acide lactique), la pression artérielle pulmonaire (PAP, par microcathéter de SuanGanz), le débit cardiaque (0, technique de dilution du colorant-cardionreen), La FC, la TA, l'ECG et le volume svstolique ( n s). L'ERP? a été calculé en divisant 1/E/V02; et les RPT en divisant Pp/fl. RESULTATS Les résultats de la fonction pulmonaire 9ont exprimés en "íringvaleurs normales (CECA); dans l'nnsemble des trois nrnunnn la fonction est PRU altérée, montrant toutefois une tßndance a 1'aunmentation du VR notamment dans les groupes 61f SI et 52. On note aussi une réduction pronrfissive de la CV dans les t.rnis oroupes mais s.tnnif inative seulement dans le proline S2. Malore 1'aunmentatlon du VR le rapport VEFIS/CU reste dans les limites physioloniques. Les résultats observas au repos et a la chame de 400 Knm.pour ce. nroupe C (le nroupe de sujets a Rx normale et fonction normale) ont été" pris comme référence pour les autres nroupes (SI et S2). L'évolution de la VE et de la U02 n'est pas différente pour trois groupes. Pour les trois oroupes la Pa02 de repos est normale. A l'effort C et SI améliorent nettement la Pa02; par contre dans le groupe S2, 3 sujets sur 8 abaissent leur Pa02. La PaC02 est normale au repos dans les trois groupes. La chute de celle-ci par hyperventilation relative a l'effort est moins marquée dans le proupe S2 pour une même ventilation d'effort. La chute du p'H est quasi identique dans les trois groupes et est a correlar avec l'augmentation de l'acide lactique. La PAP au repos est normale pour les trois qroupes; toutefois a l'effort,.le niveau atteint de PAP est le plus élevé dans le groupe S2; 4 sujets ayant une PAP 30 mm Ho. L'évolution du 0 et du Os est normale pour les trois groupes. Les RPT au repos sont anormalement élevées dans les groupes SI et S2; a l'effort les RPT s'abaissent dans les trois groupes mais la chute est moins nette pour le groupe S2. 617 * * \ I. ' ¿voluti on tins naramotres analyses par rapport a la VD? peuvent être résumé brièvement ainsi: par rapoort au oroupn de référence (c), la PAP ainsi que les RPT se montrent dss le dénart plus élevées dans les nroupes SI et S2; toutefois l'évolution a l'effort reste assez parallèle dans les trois rroupes. Par contre D et Qs ont un compor- tement similaire dans les trois nroupes. En résuma les anomalies hémodvnamiques et des naz du sano observées dans les nroupes SI et S2 sont caractérisées par une aqumentation de PAP et de RPT. au repos et a l'effort par rappprt ,au nroupe controle. Nous avons essayé d'établir des corrélations entre les paramètres hémodvnamiques et la fonction pulmonaire de repos et la Pa02 a l'exercice. Pour l'ensemble des sujets étudiés les RPT d'effort ont été córreles sinnificativement avec la CV exprimée en % de la' valeur prédite et la Pa02 a 400 Kqm.min"" ; La PflP est éqalement sinnificativement corrélée avec la C\l% mais pas avec la Pa02. Ni les RPT ni la PAP ne sont córreles avec la DLCO. (Cn conclusion rie l'évaluation fonctionnelle des patients atteints d'AS a divers stades et indemmes de BPCO évidente on peut déoaqer les points suivants: au repos, une élévation de VR plus marquée pour SI et S2 mais un rapoort l/EHS/CV conservé. Un déficit restrictif sionifi- catif n'apparaît nue nour le oroune S2. Les naz du sano sont normaux. Les PAP ßt RPT auomentent pnur les nroupes SI et S2, 1 'f-xercicf!, las paramètres ventilatnires, la V02, les débits carriianuf! et systolique restent dans les limites physioloniques. 618 Une chute do la PnD? et unn hypertensinn pulmonaire a été notée che7 Ì SP ^ ries sujets du nroune S?. Les PPT élevées au renos s'abaissent neu a l'effort. t'auomentation de RPT semble bien rorrélée avec la réduction du parenchyme nulmonaire et la chute de la PaCO? qui semble secondaire aux altérations V/0. D I U S au'a un trouble de diffusion. En effet la 0LCC1 est tres faiblement abaissée me- mo dans le nroupe S?, de nlus aucune corrélation n'a oa nu être établie entre DLCO et RPT ou PAP ou Pa02. 619 C O R R E L A T I O N S TPR Ex PpEx THP Ex VC % r = 0.48 p < 0 ..01 V C JÉ r = 0.43 p <o..05 Pa02 r = 0.45 Ï<. r » 0.17 NS r = US Ex PP TPR Pp E Pa0o Ex T1C0 * TICO JÉ °* 2 8 r = 0.30 62o RS o..01 CONCLUSION AT REST AS without BPCO ^ RV 71 with quasi normal FEV.,/VC VC \¿ significantly for S2 blood gases in normal range Pp /» PVH DURING EXERCISE * VE Q (S1 - S2) V0 2 Qs Pa02 Vg in +, 50 # of S2 Pp v 30 RP1 mm Hg in 50 5É of S2 elevated at rest remain high HEMODYNAMIC IMPAIRMENT ARE WELL CORRELATED WITH RESTRICTIVE LUNG IMPAIRMENT AND PaOg DURING EXERCISE. 621 Adántacion cardiopulmonar en el curso del ejercicio de mineros del carbon. P. García-Herreros, G. Scano, L. Stendardi, S. Degré, R. Sergysels y A. De Coster (Belgica) La evaluación funcional en reposo y durante el ejercicio de pacientes de antrasilicosis (AS) suele ser difícil porque los sujetos asocian con frecuencia una neumopatía obstructiva crónica (COLD). Por lo tanto, hemos estudiado la función pulmonar en reposo y la adaptación cardiopulmonar en el curso del ejercicio en 26 mineros del carbón, con exclusión de los sujetos con una COLD asociada evidente, clínica y/o funcional. Se clasificaron los sujetos en tres grupos según los resultados radiográficos i un grupo testigo (C)i 8 sujetos que. habían estado expuestos al polvo pero cuya radiografía era normal; un gruño SI : 10 sujetos con AS micronodular en la fase PI M3; un grupo S2i 8 sujetos con AS pseudotumoral en la fase AC. La función pulmonar en reposo muestra una insuficiencia pulmonar significativa pero ligera únicamente en el grupo S2 (VC 75 por ciento). Todos los sujetos cumplieron un ejercicio progresivo en posición sentada, en una bicicleta, con los siguientes parámetros controlados en reposo, 250 y 400 kgi ventilación (VE), consumo de oxígeno (V02), gases y lactatos en la sangre arterial (Pa02, PaC02, pH), presión pulmonar (Pp, catéter de Swan-Ganz), rendimiento cardíaco (Q, técnica de dilución cardíaca del verde brillante) y volumen de expulsión (Qs). Los valores en descanso a 400 kg no mostraron ninguna diferencia significativa entre los tres grupos en cuanto al $E, Í02« 622 ER02, pH, laccato, PaC02, Q y Qs. El Ta02 en reposo se encontró en valor normal, y en aumento durante el ejercicio en los grupos C y SI, pero sólo ligeramente en cuatro de los ocho sujetos del grupo S2. Se halló que el Pp era normal en reposo en tres grupos, pero ligeramente superior en los grupos SI y S2Í durante el ejercicio, el Pp era superior en el grupo S2, seguido por los grupos SI y C. Se observó hipertensión pulmonar durante el ejercicio (Pp ^ 30 nun Hg) en dos de diez pacientes (grupo SI) y en cuatro de ocho pacientes del grupo S2. La resistencia vascular pulmonar total (T.P.R. = Q/Pp) en reposo y a 400 kg iba en aumento del grupo C al grupo S2. En todo lo que antecede, llegamos a la conclusión de que en ausencia de una COLD asociada evidente, en una fase micronodular, pese a cierto aumento del T.P.R.. la AS es relativamente bien tolerada en cuanto a los parámetros funcionales estudiados. En una fase pseudoturooral, si bien la insuficiencia pulmonar en reposo es típicamente restrictiva, la mayoría de los pacientes desarrollaron hipertensión pulmonar y anormalidades tf/Q que afectaban al Pa02 durante el ejercicio. El aumento de T.P.R. parece vinculado a la reducción del parénqulma pulmonar y al nivel del Pa02 durante el ejercicio. En realidad podría establecer una relación linear negativa entre T.P.R. y VC por ciento (r = -0.48) y el Pa02 en ejercicio (r = -0.46). 625 THE INFLUENCE OF ASBESTOS EXPOSURE ON RADIOGRAPHIC PROGRESSION AND FUNCTIONAL DECLINE A PRELIMINARY REPORT J. E. Diem, R. N. Jones, J. C. Gilson, M. Glindmeyer, II. Weill Tulane Medical Center, New Orleans, Louisiana, USA In a three-phase study of the health effects of asbestos exposure in the asbestos-cement manufacturing industry, workers in two New Orleans area plants have been studied. The first phase, a cross-sectional study of approximately 900 workers employed at the two plants on November 3, 1969, related radiographic and physiologic evidence of asbestosis to level of exposure (1,2,3). A mortality study of 6500 current and ex-employees formed the second phase and demonstrated a dose-response relationship between excess lung cancer mortality and level of exposure (4,5). Final- ly, a cohort of the 244 male workers, aged 45 to 59 at the beginning of the cross-sectional study, is being followed longitudinally with regard to both radiographic and physiologic change. The cohort was selected with this age range in order to obtain participants who had both sufficient time to exhibit effects of exposure and high probability of continued participation in the study. The subject of this report is a preliminary analysis of the longitudinal data. Intensity of exposure between 1952 and 1969 was assessed from midget itnpinger sampling data collected by job title. Pre1952 estimates of dust levels were made by interviewing employees of long service in an effort to compare more recent dust levels with earlier conditions. This information, when combined with individual job histories, produced a profile over time of the dust concentration expressed as million particles per cubic 625 feet (mppcf) to which an individual was exposed. This profile was integrated over time to produce cumulative dust exposure (mppcf-years) which, when devided by years of exposure, yields average exposure. PA chest radiographs of each subject, taken in 1969-1970 and 1976-77, were read (side-by-side with order known) for progression of rounded small opacities, irregular small opacities, pleural thickening and pleural calcification by two readers (JCG and RNJ) using the ILO U/C 1971 Classification for definition of these features. scale« Each reader assessed progression on a 6-point real regression, apparent regression, no change, possi- ble progression, probable progression, and definite progression. Progression was then assumed to have occurred in those indi-. viduals for whom at least one reader read probable progression or higher. Otherwise no change was assumed. If one reader thought the films to be unreadable, progression was not determined. This occurred in 9 of the 204 individuals in the origi- nal cohort with two films. Of the 195 individuals with 2 readable films, 3 showed progression of small rounded opacities, 17 pro- " gression of irregular small opacities, 40 progression of pleural thickening, and 12 progression of pleural calcification. Table I presents descriptive statistics on the 204 individuals with 2 radiographs. These statistics are calculated as of the time of the 1969-1970 cross-sectional study. With the exception of chronic bronchitis there were no statistically significant differences between this group and the 40 without the two necessary films. 12.8% of those lost to 626 follow-up had chronic bronchitis at the time of the cross-sectional study. Eleven of the 40 had died. Thus there are indicators that there is a selection bias in favor of healthy individuals (the survivor effect noted in longitudinal cohort studies). In the 195 individuals on whom it was possible to assess progression, associations between progression and cigarette smoking (ever versus never), average exposure, length of exposure (years), cumulative exposure, and age at the time of cross-sectional study were sought. Time since initial exposure and length of exposure v*ere too highly correlated (r = .98) in this cohort to permit separation of their effects. First-order relationships, as determined by logistic regression, between possible influencing variables and progression of irregular small opacities, pleural thickening, and pleural calcification are summarized in Table II. Progression of irregular small opacities shows a significant dependence on average and cumulative exposure. This is in contrast to progression of pleural thickening and calcification which both depend only on length of exposure. Conclusions based on associations with length of exposure should be viewed with caution since length of exposure and time since initial exposure are synonymous in this group (r = .98) and length of exposure is heavily concentrated in the narrow range 20 to 25 years (63% of the 195 individuals lie in this range even though length of exposure varies from 3 months to 38 years). Additionally, with regard to progression of irregular 627 small opacities, the percentage progressing in the categories ^ 20 years, >20 to < 25 years, and >25 years was 0, 12.3, and 6.5 respectively, indicating a non-linear relationship between probability of progression and length of exposure. If linear relationships are sought in situations where the relationship has no linear components, then a conclusion of no association results. Because of the observed non-linear relationship between probability of progression of irregular small opacities and length of exposure, it is not surprising that the analysis performed here (where the logit was linearly regressed on length of exposure) did not produce statistical significance. Subsequent analyses will search for good fitting non-linear models incorporating lag time. In order to determine if the dependences observed in Table II were effects beyond other influencing variables, logistic regression was performed on the progression of each radiographic abnormality using age, the dichotomized smoking variable, length of exposure, and average exposure as independent variables. Table III displays for each four-variable logistic regression equation the four coefficients, standardized coefficients (coefficient/standard error), and the likelihood ratio statistics (distributed as chi-square with 1 degree of freedom) for inclusion of each influencing variable after the other three are in the equation. The results of this calculation confirm the "each variable separately" analysis given above, with the added 628 Information that smoking and progression of pleural thickening almost obtains a statistical^ significant (p = .08) relationship. The difference in the way exposure seems to relate to progression of parenchymal and pleural disease adds validity to the separate recording of these two kinds of abnormality in the ILO U/C 1971 Classification. The findings of this study also add to the evidence for differences in the natural history of the effects of asbestos on the parenchyma and pleura. In pleural thickening, progression was first detected at about 12.5 years, after which the proportions of subjects with progression increased with time up to the longest observed period of 38 years. For pleural calcification, progression started rather later, at about 20 years, then increased with time. Progression of parenchymal disease (irregular small opacities) showed a different patterni first cases of progression occurred at about 20 years, but nearly all instances of progression fell within the period 20 to 27 years, with very few beyond this period. Thus a lag period was follow- ed by progression of asbestosis» but the probability of progression increased with Increasing average and cumulative dust exposure, rather than with increasing time. These data accord with epidemiologic and clinical observations that asbestosis correlates better than does pleural disease with dust dosage. In a population with a wide range of average dust exposure and a long follow-up time, the time-dependence of pleural progression and dose-dependence of parenchymal progression should operate to produce a number of persons with 629 extensive pleural disease but no parenchymal disease. This also accords with clinical and epidemiologic experience. Ventilatory function, lung volumes, and diffusing capacity measurements are available from each of two occasions for subsets (n = 151 for ventilatory function and n = 178 for lung volume and diffusing capacity) of the original cohort. The first measurements were taken during late 1973 and early 1974, and the second approximately three years later. Mean time between visits for the 198 not lost to follow-up was 3.15 years (standard deviation = .18). Non-participation or inability of the participant to produce Acceptable spirometrie tracings or, in the case of diffusing capacity, to produce repeatable results, account for the reduction of the cohort. Multiple regression of annual change on the dichotomized smoking and cumulative exposure variables showed a significant association with cumulative exposure beyond the smoking effect only for FVC and FEVi. Table IV presents the results of these regressions together with the marginally significant exposure association for total lung capacity. Of the 155 participants with complete ventilatory function measurements and the two necessary x-rays, twelve showed progression of irregular small opacities. Table V summarizes the relationship between ventilatory function change and progression of irregular small opacities and shows that AFVC, 4FEVj, and â FEF2c TIT declined significantly more in the progressors. The association between total lung capacity and progression of irregular small opacities was of marginal statistical significance (p = .07). No significant association was found for pul- monary diffusing capacity. 63o TABLE I DESCRIPTIVE STATISTICS FOR THE 204 WITH 2 PA RADIOGRAPHS L. X Current or ex-cigarette smokers 75.5 2. X White 37.3 3. X Chronic bronchitis (MRC Questionnaire definition) Mean 2.5 Standard Deviation 4. Age' 50.9 years 4.2 5. Time since first exposure 21.9 years 6.7 6. Length of exposure 21.4 years 6.4 7. Average exposure 12.64 mmpcf 8.6 8. Cumulative exposure 288.75 nmpcf-years 631 215.75 TABLE II p-VALUES FOR RELATIONSHIPS BETWEEN RADIOGRAPHIC PROGRESSION AND POSSIBLE INFLUENCING VARIABLES* Progression of: Influencing Variables Small Irregular Opacities Pleural Thickening Calcification Age .14 .39 .41 Smoking .57 .16 .57 Length of Exposure .13 .02 .03 Average Exposure .0001 .22 .34 Cumulative Exposure .0002 .11 .19 * Based on the likelihood ratio test using a logistic regression model. Each variable treated separately. 632 o e X w I ¡s u H) M EH O O Cd H V) 1-3-> fe O H 55 1 I I o II 14 ¿¡ o 3 zs o M w en 1 o o 5e •O Ol N •ri t) Vi ïfl -H C <M S 3 o 3 s mg >-l -H h 633 4J B Ol f-l ü -HO O -H M 0) •HS i-l i-l ^ O a TÍ e •Ö <M (3 >M C T4 iH I I I II H M-I »M 0) O u U *o <w Cî **-» O C TÍ »-i (0 tt) M U O M O en c_> i IM TABLE IV PHYSIOLOGIC ANNUAL CHANGE REGRESSIONS FVC Intercept Sraokinx .052 -.034 Cumulative* Exposure (n - 151) Coefficient p-value for partial t-test FEVj^ -.00061 .014 .030 .027 .000044 .010 .030 .016 .00086 .500 .064 (n - 151) Coefficient .032 p-value for partial t-test (n - 178) TLC Coefficient .080 p-value for partial t-test * Cumulative exposure means for those participants available for use in the three regression equations are 284.6, 284.6 and 284.8 mppcf - years respectively. 634 TABLE V RELATIONSHIP BETWEEN PROGRESSION OF IRREGULAR SMALL OPACITIES AND CHANGE IN VENTILATORY FUNCTION Irregular Small Opacities Non-progressors (n=133) Progressors (n=12) Function Test X p-value S X S A FVC (ml) -.060 .069 .005 .050 .0002 A FEV (ml) -.061 .107 .017 .064. .0001 A FEF25_75 (ml/sec) -.149 .111 -.068 .129 .038 A FEF 2 5 (ml/sec) -.101 .169 -.083 .104 .59 A FEF50 (ml/sec) -.175 .136 -.224 .228 .45 Other Variables Years since initial exposure 23.3 3.17 21.5 7.24 .38 Age 52.8 4.22 50.7 4.33 .11 Average Exposure mppcf 22.0 12.4 11.6 7.67 .001 Length of Exposure (years) 23.1 3.3 21.0 6.9 .31 495.3 246.8 263.0 199.4 Cumulative Exposure mppcf-years Z Smokers 83.3 635 75.2 .0002 .53 REFERENCES 1. Weill, H., Waggenspack, C , Bailey, W., Zlsklnd, M., and Rossiter, C. : Radiographic and Physiologic Patterns Among Workers Engaged in Manufacture of Asbestos Cement. Products, 1973, Journal of Occupational Medicine, L5, pp. 248-252. 2. Weill, H., Ziskind, M., Waggenspack, C , and Rossiter, C : Lung Function Consequences of Dust Exposure in Asbestos Cement Manufacturing Plants, 1975, Archives of Environmental Health, 30, pp. 88-97. 3. Weill, H., Rossiter, C , Waggenspack, C , Jones, R., and Ziskind, M. : Differences in Lung Effects Resulting from Chrysotile and Crocidollte Exposure, Inhaled Particles IV, W. H. Walton, ed., 1977, Pergamon Press, New York. 4. Hughes, J., Waggenspack, C , Weill, H. : Mortality Study of Workers Engaged in Manufacture of Asbestos Cement Products, 1978, American Review of Respiratory Diseases, 117, p.292. 5. Weill, H., Hughes, J., and Waggenspack, C : Influence of Dose and Fiber Type on Respiratory Malignancy Risk in Asbestos-Cement Manufacturing, 1978, Submitted for publication. 636 Influencia de la exposición al amianto en la progresión radiográfica y el empeoramiento funcional J. E. Diem, R. N. Jones, J. C. Gilson, H. Glindmeyer y H. Weill Estados Unidos Estudios anteriores efectuados en esta unidad han demostrado que la presencia radiográfica y fisiológica de asbestosis y el exceso de mortalidad del cáncer del pulmón tienen una relación de.dosis en los trabajadores de las fábricas de fibrocemento. En una muestra de esta población seguida longitudi- nalmente (6 años), la duración media de exposición fue de 22 años y la dosis de exposición individual se reconstruyó utilizando la duración y el nivel medio de exposición al polvo. La exposición media en el momento de la anotación coincidía significativamente con la progresión de pequeñas opacidades irregulares (p<0,001), pero no con el fumar. El decaimiento anual de la capacidad vital forzada y del volumen de expiración forzado por segundo concordaba significativamente con la exposición pasada ( p<^0,04) más allá de un efecto de fumar significativo (p = 0,01). La progresión radiográfica estaba firmemente asociada al mayor decaimiento anual de la función pulmonar ( p<.0,001). La progresión de pequeñas opacidades irregulares parece estar más específicamente relacionada con el efecto del polvo del amianto que no el decaimiento de la función pulmonar. 637 I- l\! D_! C_Ç__S_E: 5_| VITI. I I P •' VIII . 'il.T.Ulmer •HologlcBl and Functional t*>9ts In early diagnosis oF Pneumoconiosis and rehabilitation VIII. II CI.Adrianz8. , C.Frnould., v.Sanchez Pulmonary Function oF Smoking workers exoosed to Inorganic Duat. Villi. Ill Richard R.martin., Jean-Jacque9 Gauthier et Charles Bernai Exploration Fonctionnelle dans le diagnostique pmcooe de l'Asbeatose. VIII. IV K.Nobutomo Air pollution and cytological changes in sputum VIII. V VIII. VI m.L.H.Fllndt. IdentiFicetion oF illness From allergenic dusts by T.raattaaon. , P.L.KalliomSki. , O.Korhonen., and V.Vaaranen magnetic measurements and radiographic Findings VIII. VII T.lflattsson., N.S.Huuskomen., and A.ZIttlng Correlation Between Radiographic and Physiological Findinc In asbestosis VIII.VIII T.L.Guidotti Arc Weldera'Pneumoconiosis: Studies nith advanced techniques oF scanning electron microscopy and microprobe ana- lysis, VIII. IX H.SIlbg., K.Chlyotani., V.Saito. Application oF the Four-Fold maqnlFled selective 8lveolohronchography to Pneumonloses. 659 BIOLOGICAL AND FUNCTIONAL TESTS IN EARLY DIAGNOSIS OF PNEUMOCONIOSIS AND REHABILITATION by W. T. Ulmer Pneumoconiosis Research Institute, Bochum, Federal Republic of Germany Introduction There are no real biological tests available for early diagnosis of pneumoconiosis. There are two types of functional impairment in patients with pneumoconiosis. The one is the as- bestos type = restrictive pulmonary function impairment. The best way to measure this is to measure the lung compliance. The other is the coal workers* pneumoconiosis type = obstructive pulmonary function impairment. The best way to measure this is to measure the airway resistance. Inhalation of broncho- constrictive substances can show the onset of an airway obstruction at a relatively early stage. The measurement of the airway resistance breaking volume or airway resistance breaking capacity is not appropriate for detecting early signs of airway obstruction. The recognition of the early signs of obstructive airway disease is very important for the prognosis of these workerst because there are excellent possibilities for treatment with good long-term results. There is a general agreement between our experience gained with man and our animal experiments showing that some Individuals develop, following the same quality and quantity of dust exposure, a serious pneumoconiosis (according to the X-ray or the anatomopathological findings ) and others do not. 641 In the field of pneumoconiosis due to inorganic dust, it has been suggested for many years that there might be an individual factor responsible for the fast progression and the development of pneumoconiosis. Various research teams discussed these possibilities, and at this time there are some comprehensive research projects in progress in Great Britain and in the Federal Republic of Germany to understand more about this individual factor (or factors). But till now there is to my knowledge, no biological test available for the early diagnosis of inorganic-dust pneumoconiosis. However, in the field of organic dusts which cause allergic disease by antigen-antibody reactions following dust inhalation, there are some tests available, which are either purely biological or combined biological and functional tests. The biological tests, such as the skin test or the radioallergosorbent test, are of some help and interest, but only one test can be decisive for the existence of a disease of the bronchopulmonary system due to dust inhalation, i.e. the inhalation test, which is again a combined biological and functional test. But these allergic diseases of the broncho-pulmonary system I have in mind, such as bakers' asthma or wood-dust asthma, also recognised as occupational diseases and caused by dust, are not pneumoconioses by definition. So the border line between these two types of dust-induced diseases are not always distinct (Ulmer and Berges, 1976). Among the pneumoconioses caused by inorganic.dust, coal workers• pneumoconiosis and asbestosis play the most important role. So far, however, there is no biological test available 642 for their diagnosis« Even the pulmonary function tests, which can serve as diagnostic tools, are more or less non-specific. Other non-occupational diseases also produce similar or identical changes in pulmonary function. As regards the radiographs and pulmonary function in man, however, special types of functional impairment are known, which can be very different according to the types of pneumoconiosis• For this reason it is useful to discuss coal workers' pneumoconiosis and asbestosis, because each of them is a typical example of a very particular picture of functional impairment of the lung. A large number of pulmonary function tests are available for clinicians. The better we understand the disease the less tests are necessary to become sure about the typical picture and the amount of functional disturbances. Many tests are relatively un- specific. They only show us that something is wrong, like vital capacity or the arterial blood gases. Others need a certain amount of co-operation of the persons tested, which cannot always be assumed as on forced expiratory volume manoeuvres. The best solution seems to be a small number of tests which are well-defined for special areas of the lung function and therefore are relatively specific for a particular disease. Also, the test results should be as far as possible Independent of the co-operation of the persons tested and of the motivation of the technicians. The typical functional Impairment In asbestosis Is of the restrictive pattern (Becklake et al., 1972i Becklake, 1976¡ Woltowitz and Valentín, 1977| Woitowltz et al., 1978). 643 Figure 1 shows test results of a typical case. The vital capacity Is decreased but this Is unspeclflc. The decreased com- pliance of the lung is very specific, so is the decrease In arterial oxygen pressure. Fig. 11 Typical lung function tests in a case of asbestosis with severe X-ray opacities. The airway resistance in the early stage of asbestosis is always normal, and so is the forced expiratory volume/second in percent of vital capacity (FEV). The decrease in vital capacity and the decrease In compliance are relatively early signs of the disease, and they sometimes show deviations earlier than the X-ray. But are these tests positive early enough? Coal workers' pneumoconiosis, i.e. pneumoconiosis in which silica plays an important role, gives a completely different pic- ture of the lung function disturbances. Apart from silica mostly present in the dust mixtures, which these workers inhale, there are also other components in high concentrations than silica. These other components too, influence more or less the picture of the disease (Weiler, 1977» Relchel, 1976). As we were able to show, the typical disturbances of the lung function In this kind of pneumoconiosis is the obstructive airway disease. There are for a long time no typical changes of lung. function; though there may be very severe X-ray changes, the arterial blood gases and the ventilation behaviour of the lungs are almost normal. As regards the mechanical properties of the lung, some of the cases present small restrictive functional abnormalities. the whole, however, these changes are without any important in- 644 On fluence on the well-being and working capacity of these persons (Ulmer, 1976i Ulmer and Reichel, 1972). On the other hand, some of the miners develop a serious dyspnoea. This dyspnoea is always caused by obstructive airway disease. Obstructive airway disease is a very common disease in the non-dust-exposed (general) population. Comparative studies have shown that this kind of obstructive airway disease is more often encountered in coal miners with coal workers* pneumoconiosis than in the general non-dust-exposed population showing type B and C opacities (according to the ILO classification of radiographs of 1971-72) (fig. 2 ) . Fig.21 Percentage of persons which show increased airway resistance (Rt> 3,5 cm HjO against ï sTï non-dust-exposed men. Coal workers with CWP category PQR and A and CWP category B, C of different age groups. Increased values of airway resistance were seen about twice as often in categories B and C than in the other groups. In the categories with earlier X-ray changes, however, there is no sign of a higher percentage of chronic obstructive airway disease in these miners as compared to non-dust-exposed men. Increased airway resistance is a relatively late sign of airway obstruction, especially, when the obstruction starts in the peripheral airways. Sometimes, one of the earliest signs is the hyper- sensitivity of the bronchial system to bronchoconstrictive substances (De Vries, et al., 1964| Ulmer et al., 1976). 645 An increase in airway resistance greater than R = 6 cm H^O/l's" following acetylcholine exposure under our experimental conditions is indicative of a hypersensitive bronchial system (fig. 3 ) . In a comparative study we were unable to show a more frequent hypersensitivity of the bronchial system in coal miners than in non-dustexposed men. Fig.3: Airway resistance (Rt) following acetylcholine inhalation in persons with normal reactivity and in persons with a hypersensitive bronchial system. There was some hope to find earlier signs of obstructive airway disease by measuring the closing volume or the closing capacity of the lung (Macklem, 1972). We developed a method for direct measurement of airway closure (Islam and Ulmer, 1976, 1977) by plotting airway resistance against lung volume. However, in coal miners with and without X-ray changes, the age dependency of the airway resistance breaking point, measured as closing volume or closing capacity, is comparable with the closing volume and the closing capacity of non-dust-exposed men (fig. 4 ) . Fig.41 Airway resistance breaking volume in percent of vital capacity (StaV % VC) and airway resistance breaking capacity in % of total lung capacity (StaC % TLC) in non-dust-exposed men (left) and in coal workers with and without X-ray changes in different age groups. A few words about rehabilitation. There are some excellent possibilities to control the most dangerous complication of this pneumoconiosis, i.e. the control of airway obstruction. 646 Many of the patients start too late with the important long-term treatment. In most cases we can maintain the situation of the patients at this stage by applying our treatment. In the other paper which I will present on this meeting, I will go into more detail on this point. But the results obtained during many years of sur- veillance of these coal miners show the importance of controlling any dangerous exacerbation of chronic obstructive airway disease and also the importance of a continuous adequate long-term treatment. 647 Ci., Fr. born 6. 8. 1920 • '<88 H29) IGV 3090 ml ( Ts "' ' ( 2990 ml Soil ) Compliance VC = Asbestosis 14. 3. 73 0,055 ( ¿j^pj-5) - 65 V. ( 0,3 - 0,12 = Norm ) F E V Ì / °/o VC = 75 P02a 54 mmHg ( rest ) 47mmHg (60 Watt ) PCO 2 a 38 mm Hg ( rest ) 39 mm H g (60 Watt ) Fig. 1j Typical ldng function t e s t s in a case of asbestosis with severe X-ray opacities. Frequency R t > 3.5 V. 70 -1 60 504030 - coal miner» without CWP 20 10 - -I «0 1 I 1 I 45 50 55 60 1 65 age years Fig.21 Percentage of persons which show increased airway resistance (R > 3,5 cm H^O against Í s^l non-dust-exposed men. Coal workers with CWP category PQR and A and CWP category B, C of different age groups. 648 Inhalation 3°/o Acetylcholine 1min Fig.31 Airway resistance (R ) following acetylcholine inhalation in persons with normal reactivity and in persons with a hypersensitive bronchial system. to - 'It non dust exposed men 80 70 70 «0 - Coal workers with and without changes on the X-ray 5UC |„."| y ,LC •"• St»C V. TLC Í0 S SO 40 JO 20 - a<ie (years) age (years) Fir.4: Airway resistance breaking volume in percent C of vital capacity (Stav 7. VC) and airway resistance breaking capacity in /< of total íung capacity (StaC 7. TLC) in non-dust-exposed men (left) and in coal workers with and without X-ray changes in different age groups. 649 R e f e r e n c e s Becklake, M.R. State of the art - asbestos-related diseases of the lung and other organs: Their epidemiology and implications for clinical practice Amer. Rev. Resp. Dis. 114, 187 (1976) Becklake, M.R., G.G. Fournier-Massey, C R . Rossiter, J.C. McDonald: Lung function in chrysotile asbestos mine and mill workers of Quebec Arch. Environm. Hlth 2±, 401 (1972) Islam, M.S., W.T. Ulmer: Die Strömungswiderstands-Volumenbeziehung als Maß des Closing Volumen Pneumonologie 153, 289 (1976) Islam, M.S., W.T. Ulmer: Der Strömungswiderstand in den Atemwegen und das Lungenvolumen Dtsch. med. Wschr. 102, 1187 (1977) Macklem, P.T.: Obstruction in small airways, a challenge to medicine Amer. J. med. 52, 721 (1972) Die Silikose (Anthrakosilikose) In: Pneumokoniosen. Handbuch der inneren Medizin, 5. Auflage, Bd. 4, Atmungsorgane 1. Teil, p. 159 Hrsg.: W.T. Ulmer u. G. Reichel Springer, Berlin Heidelberg New York, 1976 Ulmer, W.T.: Pneumokoniosen und Lungenfunktion In: Pneumokoniosen. Handbuch der inneren Medizin, 5. Auflage, Bd. 4, Atmungsorgane 1. Teil, p. 599 Hrsg: W.T. Ulmer u. G. Reichel Springer, Berlin Heidelberg New York, 1976 Ulmer, W.T., G. Reichel: Functional Impairment in Coal Workers' Pneumoconiosis In :.Coal Workers' Pneumoconiosis N.Y. Acad. Sci., p. 405, 1972 Reichel, G.: Ulmer, W.T., G. Berges: Untersuchungen zur Reaktionsbereitschaft des Bronchialsystems bei Gefährdung durch Inhalation von Allergenen und chemisch irritativen Stoffen Verh. dtsch. Ges. Arbeitsmed. 16, 329 (1976) Ulmer, W.T., G. Reichel, D. Nolte: Die Lungenfunktion. Physiologie und Pathophysiologie, Methodik. 2. Überarbeitete und erweiterte Auflage. Stuttgart, Thieme, 1976 65o De Vries, K., H. Booij-Noord, J.T. Goei, H.J. Grobler, H.J. Sluiter, G.J. Tammeling, N.G.M. Orie: Hyperreactivity of the bronchial tree to drugs, chemical and physiological agents In: Bronchitis II Assen, Royal Vangorcum, 1964, p. 167 Weiler, W.: Anthrakosilikose. Tierexperimentelle Forschung Bergbau-Berufsgenossenschaft,Bochum, 1977 Woitowitz, H.-J., H. Valentin: Zur arbeits- und sozialmedizinischen Begutachtung von Asbestinhalationsfolgen Prax. Pneumol. 31, 153 (1977) Woitowitz, H.-J., G. Krieger, R.H. Woitowitz: Berufliche Asbeststaubexposition und obstruktive bronchopulmonale Erkrankungen Arbeitsmedizin, Sozialmedizin, Präventivmedizin (1978 i. Druck). 651 INFLUENCIA DEL HABITO DE FUMAR EN LA MORBILIDAD RESPIRATORIA DE LA POBLACIÓN LABORAL VENEZOLANA EXPUESTA A LOS RIESGOS DE INHALACIONES PULVIGENAC. HUMOS, GASES Y VAPORES DEL MICRO CLIMA INDUSTRIAL MANUFACTURADO, ,-v? INTRODUCCIÓN: Hoy día la relación del pulmón y la vida, no solamente está medida por la función respiratoria, sino que debido a los a. POBLACIÓN LABORAL EXPUESTA A RIESGO PULVIGENO DE ORIGEN INORGANICO h f l u t a d i étel hAbko dt fkuev Matta fai *4ba1 Grupo Boad Parador P 21 22 N 1) 24 15 • J4 Total 50 /110 <0 P n 41 N 51 10 P «6 42 24 » /1«1 53 • P . 51 22 TI N 1» 20 P If 9 n • /40 12 2Sa34 15*44 45 a 54 55rnáa 4 N TOTAL Na Fumador 2M /3« 131 P = PATOLOGICO. 120 /2II 91 . » 010101 033» IM /1I2 J9 ÌMO 4J4I4 tma 14] nei 614 Slaat 1192 124 N = NORMALES. Manuel Adrlanza H. ministerio da Sanidad y Asistencia Social («ISAS) Amllker Torrsalba, ministerio dal Trabajo (HIT) Erich Semldt. Ministerio da Sanidad y Asistencia Social (PISAS) Catherine Crnould. Conlclt Francisco Fuenmayor.Instituto Venezolano da los Seguros Soclales(IVSSj Maximiliano Acosta, ministerio del Trabajo (WT) 653 ces de la Inmunología y las técnicas de ultraestructura celular le confieren una función de defensa frente a los agentes irritantes, tóxicos vivientes o inertes respirables. El macròfago alveolar, célula ésta que puede medir hasta 12 mieras en su diámetro mayor, llamada libre porque no está fi ja a la pared y se le puede encontrar tanto en los alvéolos y lavji do bronquial, hace una defensa primaria tanto frente a los microorganismos como a las partículas inertes. Igualmente el aparato mu cociliar traqueobronqulal originado en las células celíadas las cuales dan origen a más de 270 cilios por célula con propiedades pulsátiles de 20 veces por segundo sincronizadas con las células vecinas. Se estima que alrededor del 90% del material extraño dep¿ sitado en las mucosas bronquial es limpiado en una hora. El Dióxido de Silicon, el Asbesto, el Dióxido de Nitrógeno, Ozono y buen número de componentes del cigarrillo no absorb¿ dos por la membrana tráqueo bronquial dañan el macròfago y en consecuencia la función de esta célula. El humo del cigarrillo ha sido reportado por afectar el macrofago alveolar inhibiendo la actividad metabòlica y la fagocitosis. (Kennedy,J.R. and Elliot S.M. Science 168: 1097-1970 y Green,G.M. and Carolin, D: N.Engl. J. Med. 276: 421-1967) y se ha de¿ crito a la inhibición de la dehidrogenasa glyceraldeica y a la glv_ colisis anaeróbica (Green G. M. Med, Clin. North. Am. 57: 547-1973). El numero de macrófagos desciende con la exposición aguda y eumene ta con la exposición prolongada al humo del cigarrillo. (Am. Rev. Resp. Diseasm 107: 596-1973) macrófagos obtenidos del lavado bronquial mostró diferencias entre fumadores y no fumadores: 30 al 95Í de los macrófagos de los fumadores presentan material autoflorecen te de inclusiones citoplasmátlcas, refráctiles y cristaloides y mje nos del 5% en los macrófagos de los no fumadores. También las célu las polinucleares gigantes se encontraron en los lavados de 3 de once fumadores y ninguno de 13 fumadores. El daño del humo del cigarrillo al aparato mucociliar está desde hace tiempo establecido en relación con la duración a - 65* C— 2 POBLACIÓN LABORAL EXPUESTA A RIESGO PULVIGENO DE ORIGEN ORGANICO Influencia del hábito de f amar según la edad Grupo Edad Fumador No Fumador Total Xa 17 /27 10 0.0032 P 10 7 N 6 4 P 22 26 48 N 11 11 /77 29 52 13 • 24 23 • 34 P 27 25 N 4 9 33 • 44 P 23 21 N 3 7 P «2 79 N 31 31 113 ito 45 • 54 /65 13 1.9154 1.1655 44 /M 10 1.6106 55 y mí» TOTAL P = PATOLOGICO. N = NORMALES. 655 223 JC5.39 NoSígnif. P > 0.05 la exposición tabáquica, Así pues, jugando el humo del cigarrillo un papel perjudicial tan importante, la hipótesis de buscar mayores enfermedades respiratorias en los fumadores de acuerdo con los años de exposición a contaminantes del humo y ambientes profesionales es materia que justifica esta observación que hoy presentamos como nuestra población, igual que muchos otros comienzan a fju mar antes de los 20 años la agrupación por grupos de 9 años nos pa rece muy apropiada para el estudio de los efectos del factor ciga rillo. MATERIAL Y METODO; La población laboral venezolana para el año de 1978 fue de 3.890.312 y de esta clflra la población expuesta a riesgos respi ratorios fue de 309.382, (7,95?): 84.738 correspondientes a las áreas de polvos orgánicos y 154.293 al ¿rea inorgánica. Estas últimas cifras hacen un total de 239.738 trabajadores mayormente expues_ tos a riesgos de exposición específicos. La actividad de muestreo de la Encuesta Nacional de Neu_ moconiosis durante el primer semestre del año de 1978, tocó a H actividades económicas con 73.296 trabajadores,(30,5$ del universo) Se estudiaron además dos muestras de la población general en calidad de grupos testigos en las ciudades de Coro y Caucagua; centros poblados sin contaminación ambiental extra o intramural. Los trabajadores encuestados fueron inquiridos en relación con el Hábito de Fumar para calificarlos en grados de acuerdo a la intensidad, siguiendo las pautas del Departamento de Emplea-dos y Productividad de Londres. Sin embargo las comparaciones de = este trabajo solamente toma en cuenta la condición de ser o no ser fumador. Se establecieron los años de exposición profesional a los riesgos respiratorios y en general se cuantificó la intensidad de la contaminación pulvígena la cual se encontró muy alta en to-das las industrias y en todos los puestos de trabajo. 656 C —J TRABAJADORES NO FUMADORES CON EXPOSICIÓN AL rOLVO ORGANICO COMPARADO AL GRUPO TESTIGO ENFERMO NORMAL TOTAL EXPUESTOS 79 31 110 TESTIGO 20 38 58 TOTAL 99 69 168 X« = 2I,«7 P < 0,03 C — 6 TRABAJADORES NO FUMADORES CON EXPOSICIÓN A POLVO INORGANICO COMPARADO AL GRUPO TESTIGO EXPUESTOS TESTIGO TOTAL X« =6,91 ENFERMO NORMAL TOTAL 143 124 267 20 38 58 162 325 163 P < 0.03 657 Con los datos anteriores se hicieron las tablas que a continuación copiamos con los resultados expresados en porcentajes con el objeto de conocer: a) b) c) Los daños atribuíales al cigarrillo; Los daños atribuibles a la exposición profesional y; Los daños atribuibles a la combinación de ambos efectos: humo de cigarrillo más exposición profesional. Estas variables se estudiaron en el área de polvos àngánicos y en área de polvos inorgánicos dividiendo a los trabajadores entre fumadores y no fumadores y comparándola con la población testigo. Debido a los efectos conocidos del cigarrillo de mayor o menor importancia sobre la patología respiratoria específica e inespecífica investigada en la encuesta, se consideró unir todos los casos patológicos para conocer su porcentaje en cada grupo de edad en relación con los normales. El diagnóstico integrado final se hizo bien estable ciendo el hallazgo de Silicosis en los obreros expuestos a polvos de Sílice, bien a la Bisinosis o Bagazosis en aquellos sometidos a las exposiciones orgánicas específicas o bien se establecieron los diagnósticos de Bronquitis Crónica y Asma y, finalmente, a un grupo de síndromes respiratorios no completos pero con evidentes alteraciones funcionales, clínicas o radiológicas, se agruparon como OTROS diagnósticos. CONCLUSIONES: 1) (CUADRO 1.-): El aumento del tiempo de exposición al cigarri lio asimilado a través del aumento de la edad del grupo de trabajadores (N===634) expuestos a inhalaciones pulvígenas inorgánicas mostró una relación directa de efectos significantes a nivel de P 0.05. 658 C — 3 GRUPO D E FUMADORES EXPUESTOS A POLVOS ORGÁNICOS Y FUMADORES TESTIGO EXPUESTOS ENFERMO NORMAL TOTAL 236 131 367 29 48 77 265 179 444 TESTIGO TOTAL X» = 1Í.7B P < OJ» C —4 TRABAJADORES FUMADORES CON EXPOSICIÓN A L POLVO ORGANICO COMPARADO AL GRUPO TESTIGO EXPUESTOS TESTIGO TOTAL X« = ÎJ.96 P < 0.05 659 ENFERMO NORMAL TOTAL 82 31 113 29 38 77 111 79 190 2) (CUADRO 2.-): El Cuadro C-2 agrupa a 223 trabajadores expues tos a polvos orgánicos (Textileros, Tabacaleros, Azucareros, etc.), este cuadro no muestra diferencias estadísticas significativas entre Normales y Enfermos en relación a los grupos de edades. Ya habiendo hecho la observación al comprobar en la Tabla 3s-3 la inexi_s tencia de diferencias significativas entre los subgrupos de fumad¿ res y no fumadores de la exposición orgánica manufacturera. Igualmente en relación con el tiempo de exposición estudiado én la T a bla 3-4- habíamos comentado la ausencia de diferencias significativas entre los grupos menores y mayores de 10 años de exposición, lo cual parece demostrar oue en el caso de la respuesta orgánica el tiempo de exposición no juega un papel tan importante como en la exposición a polvos inorgánicos. 3) (CUADRO 3.-)i La exposición combinada del humo del cigarrillo más inhalaciones pulvígenas inorgánicas tienen efectos de significación estadística en el trabajador. i) (CUADRO ¿.-): El mismo efecto le produce la combinación humo de cigarrillo + exposición pulvígena orgánica. 5) (CUADRO 5.-): En el grupo de no fumadores los efectos de la exposición orgánica aumentan con el tiempo de exposición. 6) (CUADRO 6.-): El mismo efecto se observó en el grupo de no fu madores expuestos a polvos inorgánicos. Para terminar debemos decir que el Hábito de Fumar incre menta la patología respiratoria de manera evidente con la exposición pulvígena profesional y los factores inherentes al micro-clima laboral. Las campañas preventivas contra él "Hábito de Fumar" deben hacer énfasis en los sectores laborales en general y más especialmente allí donde los riesgos respiratorios están incrementados por la naturaleza de los procesos industriales. 66o vin/3 EXPLORATION FOHCTIONNEUF DAMS LF OT.nnNOSTiniiF PRECOCE OF L'ASBESTOSE Richard R. Nartin, Dean-Jacnues Gauthier et Charlea Bernard. Université de Montréal - Canada. "Récemment, un comité canadien charoé d'étudier les critères d'évaluation de la fonction pulmonaire dans les maladies industrielle,concluait que 1'«obeat03e risulte en une Pneumopathie restrictive classique, dont les siones fonctionnels précèdent souvent les anomalies radioloaiques". Ceci rejoint les données de Jodoin et Becklake, qui démontrèrent en 1971, chez 23 travailleurs de l'amiante avec imaqe radioloqique normale, une diminution de la compliance statique et une tendance a l'augmentation de la pression de recul élastique maximal. Par ailleurs, vu le tabaqisme important que l'on retrouve dans ce oroupe de travailleurs entre autres, (85% des sujets de cette étude) on reconnaît que la symptomatolonie aussi bien que les épreuves de fonction respiratoire conventionnelles, (capacité vitale, capacité pulmonaire totale, diffusion du monoxyde de carbone ou aradient alvéolo-artériel capillaire pour l'oxyqene) reflètent mal l'exposition antérieur. En effet, parfois nous nous trouvons dans une situation paradoxale, ou une composante tabaaisme peut conduire a un syndrome obstructif qui, comme on peut le voir au niveau des volumes pulmonaires, se manifeste par une augmentation du volume résiduel et de la capacité résiduelle fonctionnelle, alors que 661 la capacité vitale est normale ou léqerement diminuas. D'un autre coté, le syndrome interstitiel se caractérise par une diminution de tous ces paramètres. En ce qui a trait aux débits expiratoires forcés« ceux-ci sont diminiés dan9 le syndrome obstructif et normalement augmentés dans un syndrome interstitiel. Enfin, si nous étudions la diffusion du monoxyde de carbone, que ce soit au repos ou encore suite a un effort, on voit que les deux patholoqies résultent en une diminution de celle-ci. Le qradient alvéolo-artériel pour l'oxyqene sera aussi aunmenté, aussi bien dans'le isyndrome obstructif que dans le syndrome interstitiel. Ainsi, une exploration fonctionnelle respitatoire aura-t-elle deux zones d'achoppement dans l'investigation de l'abestose. D'abord, a cause des effets contraires des deux syndromes sur les volumes pulmonaires et les débits expiratoires forcés, des valeurs dans les limites de la normale en seront souvent les résultantes. En ce sens, nous pouvons dire que ces épreuves manquent de sensibilité dans la détection de la maladie. Par ailleurs, l'étude de la diffusion du monoxyde de carbone, aussi bien que celle des échanqes nazsux, sera perturbée par l'un ou l'autre des syndromes, et bien que noua puissions alors reconneître un état anormal, l'ôtioloqie est impossible a définir. Dans ce sens on doit les considérer comme peu spécifique. Les trois exemples suivants représentent bien le dilemme posé par les épreuves conventionnelles. 662 Nous avons examiné le cas d'un travailleur de 53 ans, avec une exposition totale de 18 ans dans l'industriB secondaire, dont 14 furent, de façon intensive, qui présentait un tabagisme de 35 paquets/année. Il se plainnait d'une dyspnée de orade I/IV, et a l'examen nous notions des raies secs, mais l'abscence d'hippocratisme dipital. La radioaraphie pulmonaire montrait une catégorie Sl/l - Tl/l. Le3 études de fonction respiratoire montrèrent un bilan classique d'osbestose pulmonaire: on a noté une restriction importante des volumes oulmonaires, un rapport UEHS/CU auqmenté, une capacité de diffusion du monoxyde de carbone abaissée au repos aussi bien qu'a l'effort, et le oradient alvéolo-artériel B3t élevé au repos, et augmente encore plus a l'effort. En examinant l'enregistrement d'une courbe pressionvolume, c'est-à-dire la représentation qraphique de l'élasticité parenchymateuse., I'image est clsssique. La courbe est déviée vers le bas et vers la droite, avec augmentation tres importante de la pression de recul élastique au niveau de la capacité pulmonaire totale, c'est-a-dire la pression élastique maximale. On peut citer un autre cas représentatif d'un sujet porteur d'association d'un syndrome obstructif-abestose. Agé de 65 ans, il a travaillé 37 ans dans l'industrie primaire avec une exposition intense durant 13 ans. Il avait un tabagisme de 40 paguets/année, et l'anamnese dévoile une dyspnée 1/lV alors qu'il n'y a ni raie sec ni hippocratisme dioital a l'examen. Sur le plan radioloaique, il est classifié Sl/l. Le bilan respiratoire est celui d'une bronchite tabagique, avec capacité vitale normale et volume résiduel augnante»Les débit: 663 exniratoires sont lénsrement diminués, la diffusion du monoxvde de carbone est normale au repos et léoèrement abaissée a l'effort. Le nradient alvôolo-artériel pour l'oxygène est auomenté au repos et ne change pas de fapon siqnificative a l'effort. Par ailleurs, l'étude des propriétés élastiques du ppumpn donne une toute autre perspective. La courbe est dé- viée vers le haut et vers la qauche, comme dans toute hyperinflamation, cependant sa pente est aplatie et il y a une forte aunmentation de la force de recul au niveau de la capacité pulmonaire totale, sinnes pathoonnmnniques d'une composante interstitielle significative. Le dernier exemple se rapporte plus spécifiquement au theme d'aujourd'hui c'est-à-dire au dépistaqe précoce d'un syndrome interstitiel. Un sujet de 51 ans, avec 14 ans d'exposition intense dans l'industrie primaire, présente un tabaqisme léger pour l'âqe à 10 paquets/année. Nous retenons une dyspnée l/lV,la présence de raies secs et l'abscence d'hippocratisme diqital. La radioqraphie pulmonaire est interprétée comme normale, alors que l'exploration fonctionnelle respiratoire est essentiellement normale dans toutes ses composantes. Cependant, l'étude de l'élasticité parenchymatous. et met en évidence un syndrome interstitiel frane, avec aug- mentation importante du recul élastique et déviation vers la droite de l'ensemble de le courbe. En se basant sur le fait qu'une auamentation de la rigidité parenchymateuse doit signer une atteinte interstitielle, ce qui est diamétralement opposé a ce que l'on retrouve dans le syndrome obstructif, il est looinue et raisonnable de croire que le sujet avant eu une exoo<sition suffisante a l'amiante, et chez qui on retrouve de la 664 rinidité parenchvmateuse, est porteur d'une asbestose.que sa radiographie pulmonaire soit nórmala ou non. Par ailleurs, une épreuve ou un groupe d'âoreuv/es simples qui offriraient une bonne corrélation avec la pression de recul élastique maximale pourraient être employées dans le dépistaqe précoce de l'asbestose. Un petit nombre de faux positifs et de faux néaatifs témoignerait de la sensibilité et de la spécificité de cette épreuve. C'e9t ce que nous avons voulu évaluer chez 105 travailleurs de l'amiante qui se sont présentés a notre comité de compensation dans les derniers 12 mois. Aucun critère de sélection autre que la visite a notre comité n'est entré en ligne de compte. Chez tous ces sujets, nous avons procédé a une étuda complete de la fonction respiratoire selon lea critères déjà établis c'est-à-dire capacité pulmonaire totale et set subdivisions, débits expiratoires forcés avant et après bronchodilatateurs, diffusion du monoxyde de carbone par la méthode en état stable au repos, aussi bien que lors d* un effort de 40U, de même que l'étude des échanges gazeux au repos et lors d'un effort de 40U. Par la suite, après installation d'un ballonnet au tiers inférieur de l'oesophage, le sujet étant assis dans un Plethysmographe volumétrique, nous avons mesuré les résistances pulmonaires totales de même que la relation volume-pression transpulmonaire par blocaqe itératif de l'expiration de la capacité pulmonaire totale à la capacité résiduelle fonctionnelle. Ainsi, nous avons pu reproduire la courbe prassion-volume pour chacun de ces sujets. 665 Une étude complémentaire a été effectués sur notre population. Sur 105 sujets préalablement sélectionnés, 83 présentent un dossier complet et techniquement faible. Le manque de coopération, la claustrophobie, les contractions oesophaqiennes intempestives, le manque de compréhension des épreuves, ou encore des tracés techniquement inacceptables, nous ont obline de renoncer a un nombre de 22 cas. L'objectif de cette étude était d'évaluer la prévalence d'hyper-ripiditô parenchymateuse dans une population de travailleurs exposés a l'amiante, et d'isoler des épreuves simples offrant Uns 'bonne corrélation avec celle-ci. Ainsi, un certain dente d'erreur dans le calcul de l'exposition ne devrait pas nous affecter de faoon importante. Nous avons donc évalué l'exposition de chacun en faible, moyenne et qrande, la faible ayant la valeur 1 et la qrande la valeur 3, et multiplié ce facteur par le nombre d'années d'exposition. Nous obtenons ainsi une distribution relativement symétrique et il n'apparait pas de groupe tranchant de facon évidente sur la masse. Enfin, l'examen des résultats témoiqne de l'atteinte radioloqique de notre population; 30 sujets ont une imane 0/0, c'est-a-dire essentiellement normale, alors que celle-ci est franchement positive S l/l ou plus orande chez 39 autres. 13 sujets se retrouvent dans le proupe douteux O/l et pour cette raison, ils seront éliminés de toutes comparaisons ultérieures. Ici, nous avons évalué donc deux populations bien isolées quant aux critères radioloniques, une normale et l'autre avec sinnes classiques d'asbestose. 666 Nous avons estimé qu'il serait important d'attirer l'attention sur la différence qui existe quant au nombre de sujets dans chacune des populations. Il est a noter que la population a radiographies pulmonaires positives représente 38 sujets, alors que celle avec radioqraphies pulmonaires normales ne représente que 28 sujets. Comme on a pu constater, la dyspnée demeure un sione extrêmement suqqestif, et la majorité des sujets avec imaoes pulmonaires normales ou pathologiques, se plaint d'un certein denré de dyspnée. Il n'en est pas de même cependant pour l'hippocratisme diqital et les raies secs. En effet, un seul sujet a radiographie normale présentait de l'hippocratisme digital, alors que nous n'entendions des raies secs que chez 4 sujets avec une radiographie pulmonaire normale. Cependant, ces deux signes étaient beaucoup plus fréquents chez les sujets présentant une radiographie pulmonaire positive. Les sujets a radioqraphies normales sont olus jeunes de 6 ans, et cette différence est d'ailleurs sionificativa. Par ailleurs, leur tabagisme est a toute fin pratigue identique. Tout au plus, vu la différence d'aoe, pourrions- nous croire que la population a images normales eut un tabanisme un peu plus important. En ce qui concerne la durée et l'intensité de l'exposition de nos deux populations. Nous avons trouvé une différence significative entre nos deux oroupes. Cependant, alors gu'll est probable que la différence d'âge par elle seule peut l'expliquer, pour ce qui a trait aux années d'exposition, il semble bien que, vu l'écart entre les deux moyennes (60 contre 4 3 ) , l'intensité d'exposition soit plus importante chez les sujets radioloniquement anormaux. 667 Les résultats de l'exploration fonctionnelle montrent que bien qu'il n'existe pas de différence sionificative entre les nroupes pour la capacité vitale et le volume résiduel, il est intéressant de noter une tendance a de plus petits volumes chez les sujets avec asbestose reconnue. En fait, 13 sujets avec des imanes radioloqiques d'asbestose ont une capacité vitale inférieure a 80$ de la valeur prédite, alors que nous n'en retrouvons que 5 dans l'autre oroupe. Une étude de la' diffusion au repos aussi bien qu'a l'effort d'un exercice de 40U, a été éoalement effectuée. Comme nous l'avons dit précédemmment, un syndrome obstructif tout autant qu'une atteinte interstitielle se manifeste par une réduction de ce facteur: aussi, nous nous attendrons a trouver un plus fort pourcantane d'anomalies dans ces épreuves sans pouvoir toutefois isoler l'agent causal. De fait, % i en ce qui a trait a la diffusion au repos, environ 40% des sujets dans chaque oroupe présentent des valeurs Inférieures a 80$ de la valeur prédite. Certains sujets offrant des suspicions de pathologie coronarienne, seule une partie de la population a pu bénéficié des épreuves a l'effort. Les résultats ne s'avèrent pas tres satisfaisants en ce qui a trait a la detection d'un individu, cependant la population a radiographies pulmonaires anormales montra en moyenne des valeurs plus basses. Compte tenu du tabagisme moyen avoué, une incidence de 2St des sujets présentant un VEPIS/CV inférieur a 70% est tres certainement sionificatlve, nema en acceptant une erreur de ÎOCK dans l'estimé da la dose, cette incidence est nettement plus importante que celle que l'on pourrait prédire pour une population du même age et du même tabaaisme, mais non exposée 668 a l'amiante. Malheureusement, notre type d'étude ne nous permet pas de nréciser davantane un phénomène d'addition ou de synernisme. Notons enfin qu'il n'y avait pas de dif- férence entre nos deux populations. Toute infiltration interstitielle entraînant une aunmentation de la riniditô parenchymateuse, on ne doit pas s'étonner que 75% de la populatipn avec imaaes radioloqiques présente un recul élastique parenchymateux supérieur a 1201?, de la valeur prédite a capacité pulmonaire totale. De même, ne doit-on pas s'étonner de ce qu'il v ait une différence sionificative entre les deux croupes de sujets. Cependant, une pression élastique maximale moyenne de 123% ppur les sujets a radionraphies pulmonaires normales est beaucoup plus sionificative. Déjà en 1971, Dodoin et collaborateurs avaient noté une telle tendance a l'élévation de la pression élastique maximale dans leur étude. 14 des 28 sujets présentant une radionraphie pulmonaire normale, offrent aussi des valeurs individuelles supérieures a 120%, certains allant Jusqu'à 2003. . L'abscence d'adénopathie hilaire ou d'autres sinnes de sarcoidose, de même que la faible incidence de fibrose interstitielle diffuse idiopathique dans notre milieu, nous laissent en droit de suspecter fortement la présence d'une asbestose a son début chez ces sujets. Enfin une hyper-riqidité parenchymateuse, témoionant tres certainement d'une asbestose e un stade précoce, peut être mise en évidence avant l'apparition da siqne radinloqique. En effet, lorsque nous évaluons la pression élastique maximale en fonction de notre index d'exppsition, nous obtenons une corrélation sionificative. La même corrélation se retrouve Bntre 669 la compliance statique, et notre index d'exposition, et ceci avait d'ailleurs deja été noté par Jodoin et collaborateurs, employant un index d'exposition beaucoup plus fiable. Cependant, si l'étude des propriétés élastiques parenchymatöses neut devenir une étude quasi routiniere dans un centre spécialisé, il serait irréaliste de croire pouvoir appliouer ceci a des études de dépistape en masse. * Parmi les paramètres conventionnels, d'exécution simple, nous avons évalué ceux qui seuls ou en association pouvaient offrir a la fois une corrélation significative avec la pression élastique maximale, tout en conservant un degré de spécificité satisfaisant. D'autre part dans un syndrome obstructif pur, nous pouvons prédire une chute du l/EPIS associée a une augmentation du volume résiduel liée au trapping gazeux. Ainai, le rapport de ces deux paramètres, avec le volume résiduel exprimé en pourcentage de la valeur prédite sera diminué. Compte tenu de l'aoe moyen de notre population, la rapport VEMS/CV prédit est d'environ 70$ chez une population normale de non-fumeurs. Pour le volume résiduel, comme il est exprimé en pourcentage de la valeur prédite, il serait de 100$ ou 1 dans une population normale, Ainsi, la valeur moyenne prédite pour ce rapport serait. de 70$; toute valeur inférieure a ce niveau signera donc soit une chute du rapport UEfIS/CU ou encore une augmentation du volume résiduel, ou encore l'association de ces deux signes, c'est-a-dire un syndrome obstructif typique. 670 a l'amiante. Malheureusement, notre tvpe d'étude ne nous permet pas de préciser dauantane un phénomène d'addition ou de synernisme. Notons enfin qu'il n'y avait pas de dif- férence entre nos deux populations. Toute infiltration interstitielle entraînant une aunmentation de la riniditô parenchymateuse, on ne doit pas s'étonner que 75% de la population avec imaaes radioloqiques présente un recul élastique parenchymateux supérieur a 120% de la valeur prédite a capacité pulmonaire totale. De même, ne doit-on pas s'étonner de ce qu'il v ait une différence sionificative entre les deux oroupes de sujets. Cependant, une pression élastique maximale moyenne de 123% pour le9 sujets a radiooraphies pulmonaires normales est beaucoup Dlus sionificative. Oé.ja en 1971, Jodoin et collaborateurs avaient noté une telle tendance a l'élévation de la Dression élastique maximale dans leur étude. 14 de3 28 sujets présentant une radionraphie pulmonaire normale, offrent aussi des valeurs individuelles supérieures a 120%, certains allant jusqu'à 200%. L'abscence d'adénopathie hilaire ou d'autres sinnes de sarcoidose, de même que la faible incidence de fibrose interstitielle diffuse idiopathique dans notre milieu, nous laissent en droit de suspecter fortement la présence d'une asbestose a son début chez ces sujets. Enfin une hyper-riqiditô parenchymateuse, tômoionant tres certainement d'une asbestose a un stade précoce, peut être mise en évidence avant l'apparition de siqne radinloqique. En effet, lorsque nous évaluons la pression élastique maximale en fonction de notre index d'exposition, nous obtenons une corrélation sionificative. La même corrélation se retrouve entre 669 la compliance statique, et notre index d'exposition, et ceci avait d'ailleurs dsja été nota par Oodoin et collaborateurs, employant un index d'exposition beaucoup plus fiable. Cependant, si l'étude des propriétés élastiques parenchymateuses peut devenir une étude quasi routiniere dans un centre spécialisé, il serait irréaliste de croire pouvoir appliquer ceci a des études de dépistaqe en masse. Parmi les paramètres conventionnels, d'exécution simple, nous avons évalué ceux qui seuls ou en association pouvaient offrir a la fola (JOB corrélation significative avec la pression élastique maximale, tout an conservant un degré de spécificité satisfaisant. D'autre part dans un syndrome obstructif pur, nous pouvons prédire une chute du VERS associée a une augmentation du volume résiduel liée au trapping gazeux. Ainsi, 1 B rapport de ces deux paramètres, avec le volume résiduel exprimé en pourcentage de la valeur prédite sera diminué. Compte tenu de l'aoe moyen de notre population, le rapport VEPIS/CV prédit est d'environ 70$ chez une population normale de non-fumeura. Pour le volume résiduel, comme il est exprimé en pourcentage de la valeur prédite, il serait de 100% ou 1 dans une population normale. Ainsi, la valeur moyenne prédite pour ce rBPPort serait. de 705?; toute valeur inférieure a ce niveau signera donc soit une chute du rapport V£flS/CV ou encore une augmentation du volume résiduel, ou encore l'association de ces deux signes, c'est-a-dire un syndrome ob9tructif typique. 670 Fnfi.n, comme la presninn f*lnstinut; maximalR 15t aus'îi nxorim^r. en nourcentane rie la valeur nrflrtjf-.R, la linne dn normal i té sarà aussi de IPO1"'. Toute valeur inférieure a lnn^ siqne done une norte rie recul élastique, celle supérieure a lPPr'. sinne une aunmentation de la rinldité du parenchyme. Par ailleurs, dans l'éventualité d'une atteinte interstitielle, le contraire peut se présenter: les débits cxniratoires tendent a être supernormaux, et le volume résiduel demeure inchangé ou chute lénerement. Le rapport débits expiratoires/volume résiduel sera donc supérieur a 0,70 et la pression élastique maximale doit auomenter, et ainsi se situer a la droite de la aone de normalité. En Baissant ainsi, nous pouvons donc définir 4 catégories di répartition possible d'une population. La premiere caténorie, ou le recul élastique est diminué et ou le rapport débits expirés/volume résiduel est bas, est la définition même du syndrome obstructif pur. Le deorê d'emphysème sera fonction de la chute de la pression élastique maximale. La deuxième catégorie représente exactement l'opposé; forte pression de recul élastique et rapport débits expirés/volume résiduel augmenté: c'est la définition d'un état d'hyperrinidité parenchymateuse et c'est la zone ou une amiantose pure devrait être trouvée. Enfin il demeure deux cadrans: La troisième représente une caténorie intermédiaire ou le syndrome obstructif contre-balancerait l'effet recul élastique auomenté, et résulterait en un rapport débits/volume résiduel diminué malgré une pression de recul élastique augmentée. Un trop nrand 671 nombre de sujets existant dans cette catégorie diminuerait la specificità du rapport comme moyen de dépistage. La dernière catégorie est une impossibilité physiolooique: on ne peut avoir des débits supernormaux avec une perte du recul élastique parenchymateux. Nous avons examiné individuellement les sujets avec radioqraphies pulmonaires normales. (Rapport l/EPIS/Ct/ volume résiduel en pourcentage de la valeur prédite, pression élastique maximale en pourcentage de la valeur prédite). Les catégories décrites 'sonf représentées, on a ainsi constaté que, de tous les sujets présentant un rapport débits/volume résiduel inférieur a 60%, un seul a une pression de recul élastique augmentée. Ainsi, nous pouvons dire et affirmer de fapon quasi certaine que ceux-ci sont des obstructifs purs. Par ailleurs, pour les sujets présentant une pression élastique maximale supérieure a 120% de la valeur prédite, 9 sur 14 présentaient un rapport définitivement supérieur a T0%, les 4 autres se situant entre 60 et 70%. Ainsi, si nous gardons la limite a 0,70 comme limite patholooique, 9 sujets pourraient par un test simple être détectés précocement. Par ailleurs, tous les sujets moins 1, ayant un rapport inférieur a 0,60 présentaient une pression élastique maximale normale ou franchement abaissée, signant un syndrome obstructif franc sans évidence d'altération interstitielle. Reste la région intermédiaire, 8 des 9 sujets se situaient entre 60 et 70%, et de ceux-ci 5 présentaient une pression élastique maximale franchement auamentôe. 672 Cnmntr! tenu de lRur tahanisme, eh den rinnníes récentes He Fletcher et collaborateurs et Raten et collaborateurs, qui ont 3ionalé_u/n taux de diminution annuelle du rapport VFCIS/CU deux fois plus oranri chez les fumeurs nue chez les nnn-fumeurs, (6Dml oar an Dlutot nue 30ml) il est probable que le tabaqisma devrait être pria en considération dans l'établissement de cette limite et ainsi, tnut travailleur rie l'amiante avec tabaqisma supérieur a 20 oanuets/année, avant uno valeur entre 60 et 70, riBvrait être consideró comme tres susoect de présenter une hyper-rinidité parenchymateuse. En conclusion, nous avons démontfe que dans une population de travailleurs de l'amiante, l'association fréquente d'un sydrome obstructif lié au tabaoisme rend tres difficile vnir impossible le dépistaqe précoce d'individus avec hyperriqidité parenchymateuse en utilisant le3 critères fonctionnels usuels. Chez ceux avec radioqraphies pulmonaires normales, l'étude directe des propriétés élastiques parenchymateuses a révélé que 50$ de la Dolulation présentait une hyperrioiditô. L'association de deux tests simples, le rapport VEPIS/CV et le volume résiduel, nou9 a Dermis d'obtenir une tres bonne corrélation avec le deqré d'élasticité, et de déceler précocement 9 des 14 sujets avec hyper-rigidité définitive. La zone intermédiaire déterminée avec ce test est faible, ce qui est du probablement a un choix trop ripide de la limite inférieure. 675 R X Pulm (+) Observé CU UR VENS/CV Deo R Normal 2.08 1.42 8B< 3,.52 1,.95 9.82 14..7 15.16 22 22,.01 \ E (A-a)0,_iR N 29 67* R X Pulm Observa (+) Normal CV 3.69 3.27 VR 3.42 2.1 VEMS/CV 62'S Deo— R 9.94 E 14.66 (fl-a) 0 2 — R 27 N E 24 675 12.0 R X Pultn (N) ™ »R VEHS/CU Observa Normal . 3.64 4,.05 1.83 2..01 80% Dco_R. E (A-a)02-R E: 13.3 16.,5 23 19. 1 7 13 676 1 IO in O 111 n= 28 RADIOGRAPHIE PIJLMONAIRE NORMALE 1 o IO ro O to X E (M -i Q. O CM . m . o - i O O CM O O o CD UJ z 8 1s l-sí • z> o-J 3 Eps > 677 i \ . O ^*"*-0 • o io s. co co ce 3.-=*- S aiiapud un3TVA\n 3 Q % | N 3 "SBälVNOIMIhd saiflfTTOA ! 678 o co £2 CD ce allanad LDäfS unaiVÁ VI i a % N3 3UIVNÜWTñdSÍMVT0A SIUÏN 679 to >. co co o. Œ UJ CD CE aiiaaud »naivA v i 30 % N3 sauíVÑüwnnd sai/vmoA " 680 X E o -I û- UJ S lili > 3S0. P 5 o ¿ o^ "II? o. 681 e OD — 01 f\> -t» Ol m H o O z m Oí o e m P 3J 3) x x Z + 3 II ro oí œ oo 682 Rx + : 59-7 Rx N : 53-3 AGE IO I 8 6 i 4 2 O 4 40 I 5 45 t = 3-98 • 6 50 7 55 ;UJETS 8 60 • 9 10 65 70 AGE -ANNEES TABAGISME ^ I2h Rx + : 25 Rx N : 28 t = 0-88 I 10 8 6 4 2 0 I I I 10 I 2 20 f£ 3 30 ! 4 40 5 50 683 M 6 60 70 PAQUETS-ANNEE ANNEES I6r D'EXPOSITION 14- 1 12 - Rx + : 31 Rx N •- 27 t = 2-22 108 6- "S5Î 4 2- _££ 0 I 13 2 17 3 22 iï 4 26 SUJETS INDEX i u • I É 5 31 6 35 7 40 9 10 ANNEES 8 45 D'EXPOSITION Ü Rx + : 60 Rx N : 43 IO t = 4-65 8 6 4 2 O I 13 I 2 26 1 i 3 39 4 52 6 78 5 65 68" I 7 9! ¿J 8 104 _!_ 9 IC 117 INDE) DIFFUSION REPOS lOh Rx + : 85 Rx N : 9 I Li 8 6 t= 1 0 6 1 4 2 1 54 • 2 69 ii ì 1 3 84 4 99 5 114 • 6 129 JO. 7 144 8 9 159 174 % VALEUR PREDITE SUJETS Rx + : 96 t = 2-5 Rx N : 112 DIFFUSION EXERCICE «Or 8 eh •I I 69 2 79 M 3 89. •• j i • 4 99 5 6 109 685 7 119 129 8 9 10 139 149 159 % VALEUR PREDITE Rx + : 75 t = 1-25 Rx N : 72 VEMS/CV IO 8 s i 6 4 - 1 2 O I 44 2 49 M3 54 4 59 I 5 64 I 6 69 I ^ ^ 1 7 74 i ss « 8 79 9 84 P ^ 10 89 SUJETS Pel max Rx + : 163 t= 3 34 Rx N : 123 lOr 8 lí-s? 6 1 4 2 « 1 84 1 Ï i È i 2 3 4 5 109 134 159 184 i 6 209 686 1 7 234 8 9 10 259 284 309 % VALEUR PREDITE O (0 evi O CM o CM CM X ço JJ < o > oc o ° i5 X O «a- co z co CL o >< oc aiipajd L_ O (O o _E jnajDA o o O o co oc > co UJ > > o 687 X < OC o < z o >< oc 688 1.20 -- 1.10 -Rinidité oarenchynateu l.nn -VEWS/CV .90 -- .80 -- Vol. Res.? Préd. .70 .60 -- ,5n -- .40 -- .30 -- .20 -- Intermédiaire Obstruction I 40 I I I 1 50 60 70 BO 190 100 Pel max % valeur prédite Syndroms Obstructif! VCflS/CV : 4r UR<ÍP : >f Pel max .'.Rapport V ^ Valeur prédite Atteinte I n te r 3 tit i el le : VENS/CV "RAP Pel max : f /.Rapport : noul ^ V a l e u r prédite 689 Contaminación atmosférica v cambios citologicos en los esputos. K. Nobutomo (Japón) Se comparó el aumento de la celularidad en los esputos (con células epiteliales inflamatorias y bronquiales) en dos grupos de 308 y 399 sujetos provenientes de poblaciones expuestas a niveles de contaminación atmosférica corrientes en los pafses industrializados. Se examinaron muestras únicas de esputos matutinos, y se evaluó la diferencia de aumento en la celularidad de los esputos entre los dos grupos, clasificados por edad, sexo y consumo de tabaco, aplicando el test sumario x de Mantel-Haenszel. En el grupo expuesto a una mayor contaminación atmosférica eran más numerosos los casos de aumento de los fagocitos alveolares, neutrófilos y linfocitos, pero no de los eosinófilos ni de las células epiteliales bronquiales. También se pidió a los sujetos estudiados que llenaran un cuestionario sobre los síntomas de la bronquitis crónica i el estudio mostró que la reacción inflamatoria precedía la aparición de los síntomas. Por consiguiente, los cambios citológicos en los esputos probablemente sean el indicador más sensible de los efectos de la exposición a una atmósfera contaminada. 691 IDENTIFICATION OF ILLNESS FROM ALLERGENIC DUSTS by M. L. H. Flindt, United Kingdom I have found that it is common for users of material which may give rise to allergenic dust to be, either unaware of the health danger, or to be aware of the danger but to have taken inadequate preventive precautions. Consequently, the first warning of a hazardous situation will come from identification of illness, or subclinical effects, in those exposed to the material. Unfortunately, it cannot be assumed that this identifi- cation will be made, and, if it is made, it will not always be made promptly, so I thought it would be helpful to discuss this problem. There are two main ways in which illness caused by allergenic dusts differs from those relating to the longer-established pneumoconioses. The first relates to the dusts themselves and, the second to the diagnostic criteria. In respect of the dusts themselves, the difference is a quantitative one relating to the amount of dust required to cause illness. One has only to compare the suggested threshold limit value for quartz, which in 1976 was set by the ACGIH at 3 0.1 mg/m , with that for an allergenic material, subtilisins, the enzymes derived from Bacillus subtilis, for which the suggested TLV was 0.00006 mg/m , more than a thousand times less. Theoretically, the ideal airborne level of a sensitising 693 dust Is nil, so even such a low TLV figure represents a compromise. It can be difficult enough, when, say, handling silica flour, to achieve the TLV levels for quartz, so it is clear that allergenic dusts present tal control. a major challenge in respect of environmen- This underlines the importance of identification of illness due to such dusts because, with threshold limit value bordering on the limit of detectability, the occurrence of illness may be a major factor in demonstrating a need for improved measures of prevention, apart from its role in drawing attention to the existence of a hazard ir. che first place. There are two main categories of substance which, if inhaled, may be capable of sensitising and causing allergic disease. They are substances of large molecular weight, such as proteins and certain polysaccharides, and a few substances of smaller molecular weight, which are usually highly reactive chemically. These simpler chemicals do not in themselves act as antigens. They have to be combined with a larger molecule, such as a body protein, to become a "complete antigen". The substances them- selves, the incomplete antigens, are known as haptens, but they need to be handled with the same care as other allergens. How- ever, the fact that they are haptens is not entirely academic, as their allergenicity may not be so easily anticipated or confirmed. Another consideration is that many sensitising materials are also primary irritants, capable of causing can complicate diagnosis. "direct" effects, and this However, in general, it is likely that 69A sensitlsatton effects from a given material will still occur with airborne levels well below the lowest level at which primary irritant effects occur, and, thus, measures to prevent sensitisation effects should also suffice to prevent direct effects. The other main difference between illness caused by allergenic dusts and the older established pneumoconioses relates to identification. Most of the other pneumoconioses are iden- tified and assessed by radiological changes, but, with the exception that I will describe later, a feature of the commoner occupational illnesses due to allergenic dusts is that they may cause severe functional disturbances, and even death, with no radiological changes. Hence the whole emphasis of diagnosis and assessment is different» and the role of radiology is secondary, perhaps mainly to exclude other conditions. In respect of diagnosis, it is unlikely that a relationship between the use of an allergenic material at work and allergic illness in a patient will be considered if the doctor has failed to realize that the presenting illness is indeed due to allergy. So the necessary factors are, first, that a diagnosis of allergic illness is made and, secondly, that it is deduced that the illness is, or could be, derived from a dust inhaled at work. Concerning both these factors, I think that the most important diagnostic component is the taking of an adequate history, and it will be necessary to take the history of the 695 presenting illness and the occupational history in some detail, It may be even necessary to approach the employer for further details, as not all workers are aware of the nature of the materials handled by them, or by adjacent workers. Also, as the history often includes episodes of illness that may have occurred over quite a long period, the employer's records may be more reliable than the patient's memory in respect of substances handled on given dates. In most cases where there is a type I reagin-mediated response the presenting symptoms are similar to those of hay fever or pollen asthma i Typically, a person will give a history of developing mild symptoms after he has started work on a Monday, following a week-end away from work, and he may then develop worse symptoms on the following day, perhaps persisting into the night or awakening him at night, the symptoms recurring each day with increased severity and duration until, often before the end of the week, he may be unable to continue at work. With each day away from work symptoms are likely to improve steadily. As an adjunct to the history, it is always worth enquiring whether the patient's fellow-employees have experienced similar illness. •Naturally, a degree of acumen is required not to be misled by the answer, because a pattern of respiratory illness might develop in a given group of workers which was due to transmitted infection. In respect of the history, both patient and doctor may be misled for several reasons. The first is that the patient may have been exposed to a large amount of the dust on earlier occasions without developing symptoms and then, once sensitised, 696 develop marked symptoms following a much lesser exposure. He is thus inclined to exclude a possible association between the material in question and his symptoms. This period of latency, before allergic symptoms develop, is in contrast to direct "irritant" effects which usually develop immediately after exposure, or when delayed, tend to bear a direct relationship to the amount of exposure. Additionally, direct effects tend to be most marked on first exposure, and to be less marked on subsequent exposures, with the development of tolerance or "hardening". Another cause for failure to identify the occupa- tional allergic source is that quite often the respiratory symptoms in a sensitised individual do not develop until several hours after the exposure responsible for them. A further source of difficulty is that allergic chest disease may mimic infections and other non-occupational conditions. The following symptoms and signs in various combinations may occur in patients' with type III precipitin-mediated allergic chest diseasei malaise, cough with or without sputum, tachycardia, fever, loss of weight, physical signs on chest auscultation, radiographic opacities, and leucocytosis. In consequence, a diagnosis of an infection, such as bronchopneumonia, is an understandable error, and, even in the case of more straightforward allergic asthmatic illness, I have commonly seen patients who have first been treated with antibiotics". In cases of precipitin-mediated disease, crepitations may be heard during an attack of acute alveolitis and its late 697 fibrostng stages, but these manifestations are relatively un- common. However, the commoner manifestation of asthma may be confirmed by auscultation during an attack, and in making a diagnosis of .asthma it is then important for the doctor to consider possible extrinic causes, which will include occupational ones« Even in the case of atopic asthmatics of long standing he should always bear in mind the possibility that a new extrinsic allergen has started to cause trouble. The first case of allergic asthma due to the detergent enzymes that I was able to confirm by prick-tests was an atopic who regularly suffered from pollen asthma in the summer. The attacks of asthma due to the detergent enzyme occurred in the winter, and the link between his work and his asthma was not identified by his doctor. But, even if his doctor had asked him about his occupation, he might have been misled, for the patient was an office worker who had never handled enzymes. However, his office was within a larger factory room and, a few metres away from his office door, was the tipping-in point for high-potency enzyme powder. This serves to underline the importance of probing deep- ly into the occupational history and, if necessary, visiting the workplace. As regards further investigations, if a doctor can make a diagnosis of, say, asthma and rhinitis, and the patient has been working with a recognised allergen and has given a consistent 698 history concerning Incidence of symptoms In relation to his work, there may be no useful purpose to be served by elaborate diagnostic measures, because removal of the patient to an uncontaminated workplace will normally prevent further attacks of occupational illness. As by far the commonest reaction to airborne industrial allergens, other than skin ones, is rhinitis or an asthmatic response, chest X-rays play a relatively small part in their identification. An X-ray will exclude other chest abnormalities and will serve as a base-line for future comparison, but, except in the acute, or the late fibrosing, phases of a type III precipitin mediated disease, such as farmer's lung, radiological abnormalities are not likely to be found. If the material is one for which a skin prick-testing solution is suitable and available, confirmation of a state of sensitisation may usually be obtained. However, prick tests are not always applicable and may be misleading. A negative prick- test does not conclusively exclude the suspect material as having caused the symptoms, as it is possible to cause symptoms and signs by bronchial challenge test in patients who have given negative skin prick-tests. Some substances are not suitable for prick-tests. This can be because they are highly irritant, or are such potent allergens that the normally negligible risk of sensitising the patient by doing the tests is present. Alternatively, it may not be easy to get the material into solution, or, in the case of haptens, the material will not elicit a 699 response unless coupled to the material which makes it a complete antigen. Care is needed over prick-tests. It is important that the solution is weak enough not to cause irritant or other reactions in non-exposed control patients. It is also essential to do a control prick-test on the patient with the solvent alone, to exclude dermographism, or to reveal its extent if the dermographic reaction is to serve as a control to be compared with reactions to suspect materials. The findings of sputum or blood cosinophilis is a pointer in support of allergy, but is not specific. It may be of little help in the case of an atopic patient who may also be sensitised to non-occupational allergens". The same applies to non-specific IgE. Eosinophilia, and a raised serum IgE, would be of more signi- ficance in a non-atopic worker, as I have found that both these manifestations will cease after the patient has been removed from exposure to the suspect allergen. Neither eosinophilia, nor a raised level of non-specific IgE, will contribute more in terms of practical management than an appropriate history and skin prick-tests to the suspect material. Indeed, a specific IgE test, as by RAST, will seldom provide any moire helpful information than can be obtained by a skin pricktest i They both indicate a reagin-mediated reaction, involving IgE. Simple spirometrie lung function 7oo tests will confirm obstructive changes during an acute attack of asthma, and are particularly useful in that they will also detect such changes when they are insufficiently marked to be noticed by the patient. Under ideal circumstances, a pre-exposure lung function test on the same individual will provide a more precise interpretation of changes than by comparing them with a table of "normal" values« It is also helpful, when a obstructive pattern is observed or expected , to test for reversibility - by use of a bronchodilator. This will show the degree to which the patient's airways obstruction is derived from muscle constriction, and therefore potentially of asthmatic origin. More sophisticated tests may be required if alveolar or small airway changes are to be detected. A further use of lung function tests is at the workplace to compare pre- and postworkshift values. The finding of signi- ficant changes between these tests may obviate the need for formal challenge tests. A formal provocation challenge test under hospital conditions is seldom necessary, as a good history and clearance of symptoms after removal to another workplace usually fulfills the practical needs of the situation, particularly when á known sensitiser is involved. Bronchial challenge tests should be reserved for cases of genuine doubt, perhaps when the consequences of removal to other work would be particularly disadvantageous to a patient. From the clinical aspect, I have dealt mostly with the diagnosis in individual cases, which is the way first come to light. these problems In concluding, I should like to stress again 7o1 that an epidemiological approach can also be invaluable, either in drawing attention to a problem or when following up a suspicion . One reason why the occurrence of occupational respiratory illness is not always apparent is that not all people who leave their jobs on account of chest symptoms notify their em- ployers accordingly. Indeed, the chest symptoms may be a second- ary reason for leaving. Sometimes, when I have been told by a firm that they have not had any problems with a given powder, I find that they have failed to take account of those who have left the firm on their own accord, and those who have been transferred to other departments. Consequently, although there are a few firms who deliberately try to conceal their problems, in most cases the ignorance is genuine. There is little doubt that problems of this sort can readily be missed unless they are specifically looked for. 7o2 Identificación de enfermedades producidas por polvos alergenicos. M. L. II. Flindt (Reino Unido) En dos circunstancias principales es menester identificar una enfermedad causada por polvo alergénico. En primer lugar, cuando podrían producirse efectos patológicos de índole conocida a causa de un alérgeno profesional conocidoi en segundo lugar, cuando el estado patológico se ha presentado ya y es causado por un alérgeno hasta ahora desconocido, o un alérgeno conocido que afecta a alguien de quien no se pensaba que podía ser afectado. Para distinguir una enfermedad profesional de una no profesional, es de fundamental importancia conocer la historia médica y profesional del paciente, así como para distinguir una enfermedad debida a efectos directos de la substancia sospechosa. La investigación no específica incluye el examen físico, los tests de función pulmonar, la radiografía torácica, la numeración sanguínea, la serologia y los tests de esputos. Cuando se conoce el alérgeno potencial, pueden completarse las mencionadas pruebas con pruebas específicas como la puntura cutánea, los tests serológicos de la precipltina y de la inmunoglobulina específica. En algunos de los exámenes mencionados es más útil conocer los valores individuales previos a la exposición que la gama de valores "normales". 7o3 CORRELATION BETWEEN RADIOGRAPHIC AND PHYSIOLOGICAL FINDINGS IN ASBESTOSIS Tor Mattsson, Matti S. Huuskonen, and Anders Zlttlng Department of Occupational Medicine, Institute of Occupational Health, Helsinki, Finland The correlations between radiographic findings and tests of the lung function of asbestos workers have varied (2,11,13). According to Bader et al. (1) the most sensitive Index of the progression of the disease Is the change In vital capacity, which correlates well with the radiographic changes. Different opinions have been presented concerning the value of the transfer factor In the diagnosis of asbestosls (11, 13). Asbestosls Is regarded as a disease difficult to diagnose. The problem Is to Identify early changes, which are barely outside the normal limits, and to distinguish cases, even when ad- vanced, from the many other conditions that can cause similar radiographic changes (5, 8, 12). The aim of the present study was to analyse the radiographic and physiological findings of 133 subject with asbestosls, to compare the results i and to determine the radiographic progression of asbestosls. SUBJECTS AND METHODS In 1976 the 140 living asbestosls patients of the 202 diagnosed at the Institute of Occupational Health In Helsinki between 1964 and 1976 were asked to attend a reexamination. 7o5 Of these, 133 (95%) participated. In accordance with the usual practice in Finland, we used the following diagnostic criteria for asbestosis« (a) a confirmed history of occupational exposure to asbestos dust, and (b) a positive radiographic finding of lung fibrosis. Additional supporting features includedi dyspnea on physi- cal effort, persistent basal crepitations, clubbing of fingers, reduction in vital capacity, reduction in forced expiratory volume in one second, and the single-breath carbon-monoxide transfer factor. These were not, however, used as essential diagnostic criteria. Detailed information concerning work conditions in regard to asbestos exposure and other data were available (Table I ) . The reexamination consisted of a radiographic examination, physiological respiratory measurements and a clinical examination. The radiographic examination included two full-size posteroanterior chest films and one lateral film. One of the postero- anterior films was taken with a kilovoltage of 125 and the other with 70-80 kV. 125. The kilovoltage used for the lateral film was The mAs value was adjusted to obtain films of a suitable shade. All the chest films (i.e. those taken at the time of diagnosis and those taken at the reexamination) were analysed according to the ILO U/C International Classification of Radio- 7o6 graphs of Pneumoconioses 1971 (9). They were all examined by the same three persons, two of them radiologists in the Section of Radiology at the Institute of Occupational Health and the third a specialist In occupational medicine. Vital capacity (VC) and forced expiratory volume in one second (FEV. 0 ) were analysed from flow-volume curves registered with a pneumotachograph. FEV% was calculated as (FEV. Q/VC) X 100. The single-breath carbon-monoxide transfer factor (TT L measured according to the usual procedure. ) was co Three subjects re- fused to participate in lung function tests. All the clinical examinations were performed by the same physician (M.H.). Each patient was placed In one of the follow- ing three categories i (a) smokers, who habitually carried cigarettes or cigarette tobacco for their own use, (b) ex-smokers, who had stopped smoking one year earlier or more, (c) nonsmokers, who did not and had never smoked cigarettes regularly (Table II). The statistical analyses were primarily made with the chisquare test, but in some comparisons of low frequencies Fisher's exact probability test was used. Students t-test was also used. RESULTS Radiographic findings Radiographs taken at the time of diagnosis were available for 116 of the Í33 asbestosis patients. Sixty-six of these 7o7 patients had been exposed to asbestos after the date of diagnosis. Table III shows the profusion of small opacities In the different occupational groups at the time of diagnosis and at the reexamination. The types of small opacities seen at the re- examination were as follows i s 98 (74%), t 11 (8%), u 1 (1%), p 11 (8%), q 3 (2%), r 1 (1%), and combined 8 (6%). opacities were found. No large The opacities (small Irregular or small rounded) were generally of the same type in both sets of radiographs. In the radiographs taken at the reexamination, the small opacities were more pròfuste than at the time of diagnosis. At the time of diagnosis opacities were found in the lower zones in all subjects, in the middle zones In 78%, and in the upper zones in 16%. At the reexamination the respective figures were 100%, 94% and 34% for the lower, middle and upper zones. The profusion of fibrosis and the length of exposure to asbestos varied greatly among the patients (Table IV). There was no significant difference in the type, profusion or extent of the opacities between workers in different occupations. Poor delineation of the diaphragm and/or cardiac outline was as frequent at the time of diagnosis as at the reexamination. Pleural thickening was present in 66 of the 116 radiographs available from the time of diagnosis (57%) and in 88 of the 133 taken at the reexamination (66%). In regard to the site , width and extent of the pleural thickenings, no significant differences were found between the two sets of radiographs or between workers in different occupations. 7o8 Pleural calcifications were seen in 41% of the radiographs taken at the time of diagnosis and in 59% of those taken at the reexamination. Insulators had relatively fewer calcifications than workers in other occupations ( X = 7.43ip <0.01). There was no significant difference in the occurrence of other diseases (additional symbols of the ILO U/C classification) at the time of diagnosis and at the reexamination nor between the different occupations. Of the 133 patients who were reexamined, 19 (14%) showed radiographic signs of emphysema and 22 (17%) of honeycombing. Pulmonary function Among the 130 patients reexamined, VC was normal (= 80%) in 47 (36%) and decreased (<80%) in 83 (64%). F E V 1 0 was normal in 44 subjects (34%) and decreased (<80%) in 86 (66%). T. was L co decreased (<80%) In 46 subject (35%). The patients were grouped according to smoking habits, profusion of radiographic small opacities, VC, FEV. Q and FEV%. In addition to opacities the presence of pleural thickening was evaluated, and the various groups were compared with respect to pleural changes and respiratory function. The more severe the fibrosis, the greater, as a rule, the decrease in VC and FEV, Q. T L , on the contrary, was generally co impaired only in advanced cases (fibrosis 2/3 or more). Obstruction was rarely observed among the patients (10%). 7o9 Smoking habits showed no correlation with VC, while FEV, Q correlated with smoking habits among the patients with the mildest lung fibrosis (less than 1/2)i ex-smokers had somewhat higher values than smokers (t= 1.86, p<0.07). The transfer factor, as the other lung function tests, did not differ significantly according to the smoking habits of the patients with severe fibrosis. In the groups with moderate and mild fibrosis, there was a correlation between T. habits. and smoking co In the group with moderate fibrosis, smokers showed signs of impaired diffusion when compared with ex-smokers (t= 2.42, pi.0.05) and non-smokers (t= 1.91, p<.0.07). In the group with mild fibrosis the Tt values were lower for smokers co than for non-smokers (t= 2.26, p<.0.05)f and lower for ex-smokers L than for non-smokers (t= 2.11, p<0.05). In the group with mild fibrosis, VC and FEV. n were signifi- cantly lower in the patients with pleural thickening than in those without (p<0.01i t for VC = 3.02, for FEV, Q = 2.72). No association could be shown between pleural calcifications and functional impairment. DISCUSSION The diagnostic criteria for asbestosis have been much debated (11). Some authors (7) have advocated more rigorous criteria. In the present study widely accepted diagnostic criteria were 71 o used (4). However, a person with an occupational history of ex- posure to asbestos dust and interstitial lung fibrosis does not necessarily have asbestosis. Doubt can particularly be cast on cases with a relatively slight exposure and fibrosis classified as 0/1. Furthermore, additional diagnostic criteria do not afford an absolutely certain diagnosis but only increase its probability. Of the 54 patients in whom lung fibrosis was classed as grade 0/1 at the time of diagnosis. 37 had moved to a higher grade in the follow-up. The clear progression of the condition supports the diagnosis. For the remaining 17 patients, the appa- rent quiescence of fibrosis could in many cases have been due to the short interval between the time of diagnosis and the followup. If a person has been exposed to asbestos dust and has interstitial lung fibrosis (and other signs of disease), there is no test that will rule out asbestosis, even if there is evidence for some other disease that produces similar signs. Fibrosing alveolitis, although a rare condition, should be borne in mind, since it produces similar picture (12). In the radiographic analyses the sole criterion for such qualities as "irregular" or "rounded", as well as for profusion, was the similarity to the reference films of the ILO U/C classification (9,10). Vital capacity has generally been considered to be a good 711 measure of asbestosis. Evidence has been published suggesting that it may even be affected before the disease appears radiographically. (3)t Different opinions have been presented concerning the value of the gas transfer factor in the diagnosis of asbestosis (6,13). In the present study it was generally impaired only in advanced cases. Pulmonary fibrosis is thought to be accompanied by a greater degree of functional abnormality than any of the pleural changes. The hypothesis was supported by the present study. 712 niJKKNKNCES Bader,M.E., Bader,R.A. and Sclikoff,I. (3.961) : Pulmonary function in nube?, tos i s of tho lung, an alveolar capillary block syndrome. Am.J.Med. 3J), 235-242. Badcr,M.E., Bader,R.A., Tierstc.in,A.S., Miller,A. and Selikof f,I.. (1970): Pulmonary function and radiographic changes in 598 worker; with varying duration of exposure to asbestos. Mt Sinai J.Med. N.Y. 3_7, 492-500. Becklakc,M. (1973): Lung function. Biological effects of asbestos IARC, Lyon. pp.31-39. Becklake,M. (1976): Asbestos-related diseases of the lung and oth> organs: Their epidemiology and implications for clinical practice Am.Rev.Resp.Dis. 114, 187-227. Bohlig,H. and Gilson.J.C. (1973): Radiology. Biological effects o. asbestos. IARC, Lyon, pp. 25-30. Britton, M.G., Hughes,D.T.D. and Weaver,A.M.J. (1977): Serial pulmonary function tests in patients with asbestosis. Thorax 32:1, 45-52. Evans,C.C., Lewinsohn,H.C. and Evans,June M. (1977): Frequency of HLA antigens in asbestos workers with and without pulmonary fibrosis. Br.Med.J. 1, 603-605. Fletcher,D.E. and Edge,J.R. (1970): The early radiological change in pulmonary and pleural asbestosis. Clin.Radiol. 2_1, 355-365. International Labour Office (1972): ILO U/C international classification of pneumoconioses. Occupational Safety and Health series ¿2 (rev.), Geneva, pp. 1-32. Liddel,F.D.K. (1977): Radiological assessment of small pneumoconiotic opacities. Br .J. Ind.Med. 3_4:2, 85-94. Parkes,W.R. (1973): Asbestos-related disorders. Br.J.Dis.Chest, 67, 261-300. Turner-Warwick,M. (1974): A perspective view on v/idespread pulmón fibrosis. Br.Med.J. 2, 371-376. Woitowitz,H.-J. (1976): Pulmonary function in workers exposed to asbestos. Results of epidemiological studies in Federal Republic Germany. Hefte zur Unfallheilkunde, Heft _12j6, 598-603. 713 Table I Occupation and number Insulators Occupation, number, age and length of exposure at the time of reexamination Age at the reexamination,yrs. Exposure, years < 40 40-49 50-59 ^60 ¿10 10-19 20-29 1 N= 55 15 19 20 3 mean 55.6 Asbestos sprayers N= 8 5 Asbestos cement factory workers N= 32 0 Asbestos quarry workers N= 29 1 Others N= 9 0 Total N= 133 7 1 2 7 0 1 13 23 6 29 43 6 1 0 4 15 7 mean 22.3 6 3 8 12 6 mean 21.8 mean 52.9 2 2 mean 57.3 16 mean 12.8 mean 64.0 9 22 mean 24.6 mean 41.0 2 14 ^30 5 4 54 17 714 3 1 mean 14.8 35 51 1 30 Table II Smoking habits Occupation and number Smoking habits Nonemokcrs N Exsmokors N Smokers N Insulators N= 55 8 (15%) 26 (47%) 21 (38%) Asbestos sprayers N= 8 2 (25%) 3 (38%) 3 (38%) Asbestos cement factory workers N= 32 15 (47%) 10 (31%) 7 (22%) Asbestos quarry workers N= 29 8 Others N=-- 9 1 (11%) 6 (67%) 34 (25%) 53 (40%) Total (28%) N- 133 715 8 (28%) 13 (45%) 2 (22%) 46 (35%) 1 .-( en r- r~l n c o <D <N \(N 1 (N m H i-l r-l ts rH •>* r-l \ 00 \• H »r u ^^ •P < r-) 0/1- r-( •<!• li rH »i VO rH n rH 1 1 r-l 2/3-3 fr/ 01 •H m O c u> 10 •H •a dP VO rH <N \<N | (N \rH •H in 1 rH rH oo rH o ^^ <«» O ai c oi 0 •H u 0 V a u n) 0. D Ü O O H 3 01 G H 1» •H m r- rayers u & M ^-* r- VO rH 01 M 41 42 4J rH 10 •p 93/1 1 00 o\ m arry workers < \rH ment factory ü rH 0/1 .p *-* vo rH •H N. •H IM .a m (%fr) r» M 65/13 (49% X ci « «p vo n ^ m-» n rH 5/116 arr. •H •P 13 C •H ri 20/13 2/3- 3/4 IO 0. 01 .p «i 01 43 01 0) 0 •P 01 01 43 01 01 43 10 <( < < 01 0 01 o m •p 716 O o H fc» en o n * • " /Il z Ol CN *^ ^^ n m CN oí rf5 o *r M m w ~^ z m •H n l M CN .-t V 00 o (¿> c° r- CN -H — o> 1/1 (S t~ fH m U >i a\ *-* •-< tim <a o .H ^ ^ 0P —' ^ m rH CN. n ss *~* <K> n m 1 0) ^ <*^ > m ~-* M fH CN pos 3 CO 1 X M O M . ^ m «• O w m <ff> in CM ~~ m gories v/ ss *> 00 a 4J o fi " Profus 0 •H H CN T \ ^ \ CM 1 1 l «H CN n \O \r-t \CN 717 LUNG CONTAMINATION AMONG WORKERS EXPOSED TO DUST WITH AN IRON COMPONENT Magnetic measurements and radiographic findings T. Mattsson, P. L. Kalllomäkl, O. Korhonen, and V. Vaaranen Department of Occupational Medicine, Institute of Occupational Health, Helsinki, Finland The diagnosis of slderosls has so far been based on radiographic findings and a careful penetration of the history of exposure. Iron Is an Inert dust which does not Induce flbrotlc changes In the lungs« benign pneumoconioses« Slderosls Is thus Included among the However, other more active dusts and gaseous pollutants are often Inhaled simultaneously and may give rise to flbrotlc lung lesions« Since the classical report by Dolg and McLaughlin In 1936 (5) several extensive reports have dealt with probiens related to Inhaled dusts with an Iron component (1,2.6,7,9,16,18,19,20). The radiographic changes that occur In slderosls have been described In different ways (8,13,15). The fact that siderotic changes have generally not been considered to cause disability accounts, at least In part, for the fact that less attention has been paid to slderosls than to, for Instance, asbestosls and silicosis. With a recently developed method, It Is possible to determine several lung contaminants quantitatively In vivo In persons exposed to dust with a magnetic component (3,4,11,12,17). 719 The aim of this study was (a) to evaluate the clinical suitability of applying the magnetic measuring method to mildsteel and stainless-steel welders and foundry workers» (b) to determine the amount of dust retained in the lungs of these workers, and (c) to evaluate the radiographic findings of the different groups. SUBJECTS A. Mild-steel welders Fifty-one mild-steel arc welders from two shipyards and 10 referents were examined. They had homogeneous exposure but different lengths of exposure time. Details of the exposure are presented in Table I. B. Stainless-steel welders Stainless-steel welders from eight workplaces were studied. They had used both manual metal-arc (MMA) and tungsten inert gas (TIG) welding techniques. C. Foundry workers Ten workers from an iron foundry were examined. Their occupations represented typical foundry jobs, e.g. molding, coremaking, fettling, melting and casting. Most of the workers had had a mixed exposure to sand dust and metal fumes, which, for three, included metal dust from grinding operations. The age and exposure time of the subjects in the different groups are presented in Table II. About 45% of the subjects In each group were smokers. 72o METHODS A clinical examination, including a detailed occupational history, was performed by the same physician in all cases- Res- piratory symptoms were evaluated according to the MRC standardized questionnaire (14). Lung function tests includedi spirometry, flow volume curves, transfer factor (carbon-monoxide single-breath method), closing volume (helium method), and the histamine provocation test (for stainless-steel welders only). The radiographic examinations Included two full-size posteroanterior chest films and one lateral film. One of the postero- anterior films was taken with a kilovoltage of 125 and the with 70-80 kV. The lateral film was taken with 125 kV. value was adjusted to obtain films of a suitable shade. other The mAs The radiographs were all examined and graded by two radiologists as follows i 0= normal, 1= small discrete opacities, 2= more distinct opacities, 3= numerous opacities involving both the central and lateral parts of both lungs. The method used for measuring ferromagnetic pulmonary contamination has been described in detail by Kalliomakl (10). It is based on the permanent field of magnetized particles. First the thoracic area of the subject is magnetized in a low external magnetic field. Thereafter the permanent field caused by conta- minants is measured with a sensitive magnetometer on five transsectional planes of the thoracic region, both on the anterior and posterior sides, because the spatial resolution of the magnetometer is only about 100 mm (Figure 1). 721 Thus the distribution of contaminants could be evaluated from the measured permanent magnetic field (PMF) curves. As a first approximation the half widths of the PMF curves, both in the transverse and longitudinal directions, represent the distribution. The half width is the distance between the two lateral points of the PMF curve where its height has reached half of the maximum value. The results have been expressed as the average magnetic field (AMF), and converted to the estimated amount of contaminants in the lungs. RESULTS A. Mild-steel welders For studies investigating lung retention and clearance under continuous exposure, the shipyard welders served as suitable subjects because their exposure was homogeneous. According to these studies, retention and clearance seem to be balanced after five years of continuous exposure. The average of the measured magnetic fields (B), the geometric standard deviation (J ), and the approximate equivalent o amount of welding dust are shown in Table III. Figure 2 shows the estimated amount of lung contaminants in welders from the same shipyard. A good correlation between the radiographic findings and the magnetic measurements has been shown before (10). B. Stainless-steel welders The estimated amount of retained dust averaged about 20 mg for TIG welders and 600 mg for MMA welders. 722 The radiographic changes were In all cases discrete, but it was possible to grade them into the three categories. The interpretation of the radiographs was performed critically, and nonspecific changes such as old Inflammatory changes were taken Into consideration. Such changes were found In 377. of the subjects when even slight abnormalities were noted. Changes that could be attributed to Inhaled dust were encountered In 17 (25%) of the subject (grade 2-3 changes). In addition, 30 subjects (45%) showed very discrete changes (grade 1 changes). These results are preliminary and further evaluations will be made in connection with the planned follow-up studies. C. foundry wo»*?" The mean value of the measured average magnetic field was 0.8 nT (range 0.1 - 8 nT), and the typical amount of retained contaminants was 200 mg (range 30 - 600 mg). An attempt was made to differentiate the radiographic changes caused by quartz and metal particles. The changes encountered seemed to be primarily caused by metal dust. Thus "siderotic" lesions were noted In all of the subjects» whereas "silicotic" changes occurred In only half of the subjects. The radiographic findings correlated with the measured average magnetic field. In this study there was no blurring of the heart outline, nor any confluent opacities. The hilar shadows appeared prominent In some cases, but the hilar nodes were not enlarged. In these series possible regression of the lesions has not yet been eva- 723 luated. DISCUSSION In this study, three groups were examined which represented exposure to metal aerosols in different occupations. Shipyard welders were chosen because of their homogeneous exposure, which aided the study of lung retention and clearance rates under continuous exposure. Stainless-steel welders formed an heteroge- neous exposure group In that welders use several welding techniques. The last group,; thqt of foundry workers, was selected to represent all typical occupations, because the properties of foundry dust differ from one foundry occupation to another. In addition to determining the average amount of retained lung contaminants for each group, we gained a conception of lung contaminant distribution. The estimated amount of lung contami- nants in the groups differed by more than one decade. The content of lung dust was the highest In shipyard welders. This variation was due to the differences In exposure, and perhaps also to different deposition and clearance rates. Determining the cor- relation between retained lung content and the concentration of Inhaled pollutants will require systematic follow-up studies. A correlation between the radiographic findings and the amount of contaminants was found for the mild-steel arc welders and foundry workers. Conclusions regarding pathogenesis, the health hazards caused by Inhaled aerosols In each group and the doseeffect relationship would require more extensive data than were provided by this study, as well as follow-up studies. 12H REFERENCES Barhad,B., Teculescu,D. and Craciun,0.(1975): Respiratory symptoms, chronic bronchitis and ventilatory function in shipys welders. Int.Arch Occup.Environ.Hlth, 3j5, 137-150. Charr,R. (1953): Respiratory disorders among welders. J. Amer.Med.Ass. 152,1520-1522. Cohen, D. (1973): Ferromagnetic contamination in the lungs and other organs of the human body. Science 180,745-748. Cohen, D. (1975) : Measurements of the magnetic fields produced by the human heart, brain and lungs. IEEE Trans.Mag. 11,694-700 Doig, A.T. and McLaughlin, A.I.G. (1936) X-ray appearances of the lungs of electric arc welders. Lancet 1, 771-775. Einbrodt, H.J., Maass, W., Josten, H-G. and Stecher, W. (1971): Untersuchungen Über die Lungenveränderungen bei Elektroschweiss öffentliche Gesundheitswesen, 3_3, 286-299. Enzer, N. and Sander, O.A. (1938): Chronic lung changes in electric arc welders. J.Ind.Hygiene and Toxicology, 2Q_:S, 333-3 Haglind, 0. (1972): Occupational health in the shipbuilding industry. Safety and health in shipbuilding and ship repairing Occupational safety and health series 27. International Labour Office, Geneva, pp. 5-12. Harding, H.E., McLaughlin,A.I.G. and Doig, A.T. (1958): Clinical, radiographic and pathological studies of the lungs of electric-arc and oxyacetylene welders. Lancet, 2_, 394-398. Kalliomäki, P-L. (1977): Measurement of Magnetic Lung Contaminain Vivo: Evaluation of the Method and its Application to Arc Welders. Doctoral dissertation, Helsinki, 64 p. Kalliomäki, P-L., Alanko,K., Korhonen, 0., Mattsson, T., Vaaranen, V. and Koponen, M. (1978): Amount and distribution of welding fume lung contaminants among arc welders. Scand.J.Work Environ.» Health, £, 122-130. Kalliomäki, P-L., Korhonen, 0., Vaaranen, V., Kalliomäki, K. anc Koponen, M. (1978): Lung retention and clearance among shipyard arc welders. Int.Arch.Occup.Environ.Health, (in press). Kleinfeld, M., Messite, J., Kooyman, 0. and Shapiro, J. (1969): Welders' siderosis: A clinical, roentgenographic and physiologic study. Arch. Environ.Health, 19., 70-73. Medical Research Council's Committee on the Aetiology of Chronic Bronchitis: Standardized Questionnaire on Respiratory Symptoms. (1960). Brit.Med.J. 2_, 1665. Parkes, W.R. (1974): Occupational lung disorders. Butterworth s. Ltd. London. 725 2 16. Piscator, M. (1976): Health hazards from inhalation ®f metal fumes. Environmental Research. Ll:2f 268-270. 17. Robinson, S.E., Freedman, A.P. and Johnston, R.F., (1977): Non-invasive Magnetometric Determination of Lung Dust Loads in Active and Retired Coal Workers. The Hahnemann Medical College and Hospital Philadelphia, Pennsylvania 19102, 103 p. 18. Schüler, P., Maturana, V., Cruz, E., Guijon, C., Vasquez, A., Valenzuela, A. and Silva, R. (1962): Arc welders' pulmonary siderosis. J.occup. Med. £, 353-358. 19. Slepicka, J., Kadlec, K., Tesar, Z., Skoda, V.. and Mirejovsk?, P. (1970): Beitrag zur Problematik der Elektroschweisserpneumokoniose. Int. Arch.Arbeitsmed. 2J, 257-280. 20. Spac'ilova, M. and Koval, Z. (1975): Pulmonary X-ray and functional findings in electric-arc welders. Int. Arch.Arbeitsmed. 34:3, 231-236. 726 TABLE I GROUP MILD STEEL WELDERS N EXPOSURE . MEAN TIME/Y. LENGTH OF RETIREMENT,Y. MEAN SD SD o REFERENTS 10 0 SHIPYARD A - GROUP 1 - GROUP 2 - GROUP 3 - RETIRED 9 8 17 7 1.8 10 18 26 6 7 SHIPYARD B - GROUP 1 - RETIRED 5 5 18 • H 30 3 0.1 t\ 727 0 0 0 1.6 1.1 0 7 l\ TABLE II OCCUPATIONAL GROUP AGE AND EXPOSURE TIME N AGE MEAN SD EXPOSURE (YRS) MEAN SD A. MILD STEEL ARC WELDERS 51 39 10 14 7 B. STAINLESS STEEL WELDERS 68 36 10 13 .8 C. FOUNDRY WORKERS 10 58 6 33 7 728 TABLE III RESULTS OF MAGNETIC MEASUREMENTS IN MILD STEEL WELDERS GROUP B, NT ¿ G REFERENTS AMOUNT OF DUST, MG MEAN RANGE <1 0.003 SHIPYARD A - GROUP 3 0.2 1.1 1.5 •3.5 - RETIRED 0.83 1.7 27 190 200 110 1.9 1.5 3.0 2.3 700 200 - GROUP 1 - GROUP 2 2.0 3.6 13 25 30 10 - 53 - 1500 - 1500 - 250 SHIPYARD B - GROUP 1 - RETIRED 729 150 - 2000 60 - 500 LU • • M \ I 1 / < •H o •r| 4J 0) c Ol BUI \ 3 0 -0 r-l 01 OL 1 1 1 iH o\ •H 73o five tran e 0 sterio rly i CD 0 "0 "D (0 CO u u 0 0 (D a s S s „? sec tional s measure i Ol > manent n 1 01 ant eriorly a •0 ure o nte ost m to E 0) o c 3 O O) EE ^ (O (M (O 4J c c <£> +1 •H oo •o m >. a •H ta öi a> IM 0) X! •I o o c tí +1 00 O) 3 O U •O n n (V X) E, u|8 So 0) (D U Oufw =2w 0 a.^+1 x = 5 UII-3 H ce+i UJUÍS 0CQ.3 g. 8 u. 731 4J ARC WELDERS' PNEUMOCONIOSIS! STUDIES WITH ADVANCED TECHNIQUES OF SCANNING ELECTRON MICROSCOPY AND MICROPROBE ANALYSIS Tee L. Guidottl Dept. of Environmental Health Sciences, The Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland, U.S.A. Jerrold L. Abraham Dept. of Pathology, University of California at San Diego School of Medicine, La Jolla, California, U.S.A. Phillips B. DeNee Appalachian Center for Occupational Safety and Health, NIOSH, Morgantown, West Virginia, U.S.A. (Present address i Lovelace Foundation, Alburquerque, New Mexico Josef R. Smith Dept. of Pulmonary Medicine Youngstown Hospital Association, Youngstown, Ohio, U.S.A. Arc welders' pneumoconiosis is compatible with a long and vigorous life. Patients with the disease seldom come to necropsy during their working years so that the pathologic findings of the condition are not fully characterized. A recent case pro- vided the opportunity to study the condition using newly developed, sophisticated analytical techniques. A previous report summarized the case and salient features of histology and elemental analysis. This discussion will examine additional instructive findings and will use the case to demonstrate and to validate the recently developed techniques. 733 Case History The patient was a 58 year old white male who had been a welder for 39 years with no other occupation or knowidust exposure. He smoked two packs of cigarettes daily. For 15 years before his death, he had a gradually increasing, bilateral micronodular and interstitial pattern on serial chest films (Figure 1). rous, with Despite this, he was in excellent health and vigono respiratory complaints or limits to exertion. His hematocrit was 45% before his death. For two weeks prior to his death, he experienced a febrile, influenza-like illness that ran a fulminant course progressing to pneumonia, respiratory failure, congestive heart failure, and finally cardiopulmonary arrest. Sputum cultures, viral antibody titers, and cold agglutinins all failed to implicate an organism. He was treated with oxygen, antibiotics, assisted ventilation, and diuretics. At autopsy, the lungs were brick red and honeycombed with fibrosis. There were extensive subpleural and deep plaques of black pigment. Methods Lung tissue from the necropsy in Youngstown, Ohio, was fixed in buffered 10% formalin solution and blocks were embedded in paraffin. Sections were stained with hematoxylin and eosin, Van Gieson's stain for elastin, and Prussian blue stain for iron and were examined by light microscopy. 734 The tissue was prepared for scanning electron microscopy following standard methods used at the Appalachian Center for i .i- Occupational Safety and Health. Two paraffin sections were deparaffinized and critical point dried with liquid CC^. An evaporated carbon coating was applied to enhance electrical (R) conductivity. The sections were then scanned with an Etec1--^ scanning electron microscope (SEM) using both secondary electron (SE) and backscattered electron (BSE) imaging. The principles and differences in these techniques will be described below. The SEM system was interfaced with an Ortec^ solid-state detector with a Northen Scientific V* 880 multichannel analyzer. The accelerating voltage was 20 keV and the specimen tilt angle was 45°. The detector was a modified solid-state backscattered 2 electron detector available commercially. The principle of microprobe analysis is the detection by spectrophotometry of electromagnetic energy in the X-ray wavelength which is generated by bombardment of the target with electrons. When an atom in the target is excited by capture of an electron it becomes energetically unstable and ejects an electron to return to a stable energy state. The energies with which these so-called "secondary electrons" are ejected reflect the binding energies i photons of X-ray energy are also given off and balance the energy equation. These X-rays are of a set of wavelengths characteristic of the atomic number of the atoms in the target. identified. In this way, elemental composition can be The secondary electrons ejected from the excited atoms are the signal generating the secondary electron image. 735 Backscattered electrons are electrons which are reflected back from the target when the target Is bombarded by the cathode ray (electrons). The technical details of these phenomeona have been well summarized and the state of the art has progressed further since this study was performed. ' ' Results A typical high-power view is shown in Figure 3 with an alveolar macrophage in the center field. The BSE image in Figure 4 clearly identifiés a large particle of approximately 14 yüm diameter within the cell. The particle is not visible in the SE image in Figure 3 because it is obscured by the overlying plasma membrane and cytoplasm. The BSE signal derives from the reflection of electrons that have penetrated a fewyum into the cell and are then reflected from the surface of the particle. Microprobe analysis yields the spectrum seen in Figure 5. The two spectral lines, termed K«. and Kg, are unique to element 26 which is iron. Thus the system is capable of locating particles contained in the cells and of Identifying their elemental composition. A peribronchial alveolus is selected in Figure 6, arrow. The cathode-ray (primary electron) beam is very narrow (0.1 yum diameter), permitting exceedingly fine resolution of elemental distribution. Thus, iron was demonstrated in the macrophage in the alveolus (Figure 7, labelled a), but was present only in trace amounts in the lnterstitlum. 736 This fine resolution maps the elemental distribution over the morphological Image with great precision. An unexpected finding was a flbrotlc plaque with the characteristic whorled morphology of silicosis (Figure 8). Within the Interstices of the loose fibrous stroma of the plaque are a number of cells, Including the macrophage In the center of Figure 9. This macrophage bore a large extrusion, seen In the fore- ground of Figure 10. Examination by three-dimensional SE Imaging was performed by changing the specimen tilt angle slightly and then viewing both Images through a stereoscope. appears to be in continuity with certainly a pseudopod. The extrusion the cell body and Is almost BSE Imaging demonstrated a particle In the distal part of the pseudopod, which microprobe analysis revaled to contain Iron. and within the In other macrophages In this plaque, fibrous stroma In lesser amounts, traces of silicon were Identified. Discussion Scanning electron microscopy In this case the diagnosis of arc welders' pneumoconiosis had already been made. The SEM studies were primarily intended to demonstrate the utility of pneumoconioses. the techniques In studying the It thus came as a surprise when evidence for an unsuspected second process appeared. The case shows how versatile and precise these methods are when applied to heterogenous chemical systems such as a pneumoconlotlc lung. The various SEM methods used In this study are complementary! 737 (1) SE Imaging yields data on surface features and morphology. The image is psychologically familiar and relatively easy to interpret. It is easy to construct three-dimensional views. (2) BSE imaging penetrates several hundred A below the surface and identifies objects, such as intracellular particles, that cannot be seen by SE imaging. Thus BSE images are similar in some res- pects to transmission electron microscopy because they both reveal some degree of internal structure. The BSE signal is strongest with reflection from an object of high atomic number, so that some information can be gained regarding chemical composition. This is particularly useful in the case of metal pneumoconioses because the contrast is strong and makes location of the particles obvious. (3) A BSE imaging technique that was not used in this study is hlstochemical staining using metal ions. It is possible to stain tissue with metal stains such that surface features stand out in BSE as clearly as in the SE image with appropriate hlstochemical methods. Localization techniques can show the distribution of 2 7 enzyme activities or a variety of chemical characteristics. This feature is not very useful in metal pneumoconioses because the elemental composition of the dust is obscured by the content of the hlstochemical stain. (4) Microbeam analysis is a convenient and non-destructive method of elemental analysis, which allows the elemental distribution to be mapped over the visual image. With its narrow beam and high resolution, this mapping can be quite precise down to the cellular and sometimes even subcellular localization. 738 Microprobe analysis can detect elements with atomic numbers from sodium (11) through uranium (92). Although it is not particularly sensitive for low concentrations, requiring 0.1 to 1.0% content by weight before an element is detectable, it is capable of detecting 10 g of the heavier elements with sufficient concentration in the field of the beam. Unfortunately, it cannot be used to identify specifi compounds, nor can it detect light elements such as oxygen or hydrogen. Other techniques, such as secondary ion mass spectro- metry or Raman laser microprobe analysis, must be used for these purposes. 4' 7 o Since the earliest demonstrations, techniques of scann- ing electron microscopy have proven their utility In the study 1-3 6 of pneumoconioses. ' They have an Important role In o basic studies of particle handling and distribution in the lung. These methods may be useful diagnostlcally If the cause of the lung disease Is unknown, or If the exposure source is not obvious. ' In most cases, precise Identification of the metal would not have Important Implications for therapy. The role In diagnosis Is further limited by the expense of the SEM equipment and the need for highly trained technicians and pathologists. In a national research center such as the Appalachian Center for Occupational Safety and Health, cases can be studied on referral. Finally, a major Intrinsic limitation of the field of electron microscopy In general applies to these techniques. The amount of tissue sampled is exceedingly small compared to the total mass of the organ, and it Is seldom practical to correct the sampling 739 error merely by examining more sections at random. One must there- fore take great care in selecting representative tissue blocks and must be cautious in extrapolating findings beyond the limits of the data. Arc welders' pneumoconiosis Arc welders' pneumoconiosis has been recognized since 1936, when it was first described by Doig and McLaughlin. The pre- valence of the X-ray findings of this condition varies with age 12 and duration of employment as an arc welder. Pulmonary function abnormalities appear to be associated with a history of chronic bronchitis among welders , and probably also with smoking history The correlation between X-ray changes and pulmonary function abnormalities is much less clear. In one extensive study on several worker groups In a Polish shipyard, Dobrzynski, Kisielewicz, and Koclecka studied 50 arc welders with a mean age of 38 years and an average duration of employment of 12.4 years. They found an overall prevalence of chest film abnormalities of 92X in their unselected population. Arc welders who smoked (68%) had the same prevalence of X-ray abnormalities (67.ST. of all abnormalities, as reported in the paper) as non-smokers, but gave a history of chronic bronchitis more often (77.5% of total positive histories for chronic bronchitis), and were more likely to show obstructive patterns on pulmonary function testing (.807. of such abnormal tests). Thus, holding the X-ray categories constant, the prevalences of pulmonary symptoms and 74o functional abnormalities appear to vary with smokingi there does not seem to be much association between these findings and radiological abnormalities'. The lack of a sufficiently large subgroup of arc welders without X-ray changes makes this conclusion tentative. Further data on this high-risk population would be welcome. A similar group of Polish arc welders studied by Marek and his colleagues demonstrated surprisingly low exercise capacity and pulmonary function during exercise despite their relative youth. These were 30 young shipyard welders with micronodular patterns on chest film whose physiological performance with exercise compared unfavorably with 30 young coal miners matched for age (35 to 45), duration of employment (about 10 years), weight, height, and gradation of X-ray abnormality. Such comparisons between worker groups may prove very useful in assessing the differences in the pathophysiology of the pneumoconioses. These two studies suggest that there is more than meets the eye in reading the chest film when it comes to arc welders' pneumoconiosis. The simplistic concept of the condition as an accumulation of ferric oxide (Fe^Oo) in the lung is inadequate to explain the Striking differences In prevalence between populations and the lack of a close association between chest film abnormalities and Impairment of pulmonary function. ' The simplest explanation for these observations is that other Inhaled agents besides Fe 2 0 3 play a major role In modifying the response to the Inhaled dust and contribute their own pathological 741 features. Nitrogen dioxide is one such agent known to exist as a hazard in welding and may serve as a model for study. Silica is another and was an additional feature in the patient we have described. Arc welders' penumoconiosis is more complicated than we thought it was. 742 References 1. Guidottl TL, Abraham JL, DeNee PB, Smith JR. 1978. Arc welders' pneumoconiosis: Application of advanced scanning electron microscopy. Arch Environ Health 33:117-124 2. Abraham JL, DeNee PB. 1974. Biomedical applications of backscattered electron imaging-One year's experience with SEM histochemistry. Scanning Electron Microscopy 1974 (Proceedings of the 7th Annual Scanning Electron Microscope Symposium). Chicago, ITT Research Institute, pp. 251-258 3. DeNee PB, Abraham JL, Gelderman AH. 1973. Methods for a SEM study of coal workers' pneumoconiosis. Scanning Electron Microscopy 1973 (Proceedings of the 6th Annual Scanning Electron Microscope Symposium). Chicago, ITT Research Institute, pp. 411-418 4. Woldseth R. 1973. Kevex Corp. 5. Maugh TH II. 1977. Electron probe microanalysis: New uses in physiology. Science 197:356-358 6. Abraham JL. 1978. Diagnostic applications of microanalysis. Presentation to the Annual NIH Instrumentation Symposium, Bethesda, Maryland, 7-9 August 1978. 7. Abraham JL, DeNee PB. 1973. Scanning electron microscope histochemistry using backscattered electrons and metal stains (letter). Lancet 1:1125 8. HoIman B. 1969. Scanning electron microscopic observation of particles deposited In the lung. 18:330-339 9. Sorokln SP, Brain JD. 1975. Pathways of clearance in mouse lungs exposed to iron oxide aerosols. Anat Record 181:581-626 X-ray Energy Spectrophotometry. Burlingame, California, 10. Siegesmund KA, Funahashl A., Pintar K. 1974. Identification of metals from a patient with interstitial pneumonia. Arch Environ Health 28:345-346 11. Dolg AT, McLaughlin AIG. 1936. X-ray appearances of the lungs of electric welders. Lancet 1:771-775 12. Attfleld MD, Ross DS. 1978. Radiological abnormalities In electric arc welders. Brit J Indust Med 35:117-122 13. Spacilova M. Koval Z. 1975. Pulmonary x-ray and functional findings in electric-arc welders. Int Arch Arbeitsmed 34:231-236 14. Peters JM, et al. 1973. Pulmonary function in shipyard welders- An epidemiologic study. Arch Environ Health 26:28-31 15. Dobrzyfiski, Kisielevicz J, Kociecka I. 1970. (Clinical and statistical analysis of chronic bronchitis in port and shipyard workers.) Medycyna Pracy 21:294-306 (Polish, summaries in English and Russian) 743 16. Marek K, et al. 1970 (Effort capacity In patients with initial pneumoconiotic changes.) Polski Tygodnik Lekarski 25:1015-1018 (Polish, abstracts in English and Russian) 17. Guidotti TL. 1978. The higher oxides of nitrogen: A role in altering pulmonary response to injury? Presentation to the 5th International Conference on the Pneumoconiosis, Caracas, Venezuela, 30 October 1978. 744 Neumoçonlosis de los soldadores con arcoi estudios con técnicas avanzadas do microscopía electrónica de exploración y análisis por microsondeo. T. L. Guidotti (Estados Unidos) Rara vez se consigue material de necropsia de pacientes con neumoconiosis de soldador con arco, ya que esta enfermedad rara vez es mortal« El caso actual era un hombre de 58 años de edad que llevó hasta el fin de sus días el diagnóstico basado en la historia clínica y en la radiología torácica. Se encontró la pigmentación característica mediante un examen somero de los pulmones y con la microscopía luminosa con azul de Prusia. La microscopia electrónica de exploración demostró claramente una importante infiltración celular entre los espacios alveolares, en el tejido intersticial y en los intersticios de los nodulos fibróticos areolares verticilados. Las imágenes electrónicas retrorreflejadas, que aportan información sobre los rasgos por debajo de la superficie y sobre el número atómico elemental, demostraron numerosas partículas intracelulares con numero atómico elevado. El análisis por microsondeo identificó concretamente el hierro como elemento predominante en las partículas, pero también reveló una tnexperada presencia de silicon asociada con los nodulos. Las imágenes electrónicas retrorreflejadas resultaron muy útiles para identificar ciertas características para el análisis elemental por microsondeo. Estas técnicas adelantadas confirman lo ya descubierto por métodos tradicionales y contribuyen a obtener nueva Información. Son muy adecuadas para estudiar los sistemas químicos heterogéneos y los tejidos complejos como el del pulmón. 745 APPLICATION OF THE FOUR-FOLD MAGNIFIED SELECTIVE ALVEOLOBRONCHOGRAPHY TO PNEUMOCONIOSES Hlsao Shlda, Kelzo Chlyotanl, Yoshlakl Salto Department of Radiology and Internal Medicine, Rosal Hospital for Silicosis, 632 Takatoku, Fujlwara, Tochtgl Prefec, Japan. Plain chest films have been one of the primary aids In the diagnosis of pneumoconiosis and have been useful In the assessment of pulmonary Impairment. However, they may not always exactly show the features of respiratory disease, for example, pulmonary fibrosis, emphysema and focal emphysema or duct ectasia. The histological aspect of pulmonary Impairment has been dealt with by many authors, but there are several discrepancies between radlographlcal and histological findings of pulmonary function test results. The four-fold magnified selective alveolo-bronchography (S.A.B.) Is a useful procedure which can clearly represent the anatomy at the levels of the air-conducting systems. With the aid of slides the authors demonstrate that the manifestation of pathological air space is difficult to be detected by conventional bronchography, but that four-fold magnified S.A.B. enables typical centrllobular emphysema to be made visible, whereas the chest radiograph taken In a case of silicosis reveals no significant small opacities and no evidence of pulmonary emphysema. In another case of silicosis, the S.A.B. demonstrates typical panaclnar emphysema, features of which are marked 747 destruction of alveolar architecture. In a case of a foundry worker's lung, the chest radiograph shows disseminated mlcronodular opacities In the upper lung fields and a hyperlucent area In the lower lung fields. The S.A.B. demonstrates typical centrllobular emphysema In the upper lung, which area Is not hyperlucent In the plain film. In the lower lung the S.A.B. demonstrates panlobular emphysema, a progression from centrllobular emphysema. In a case of slderosls with Increased abnormal pulmonary markings and bullous emphysema, the S.A.B. demonstrates a typical centrllobular emphysema and focal emphysema, associated with bullous emphysema In the right middle posterior segment. The S.A.B. of the lower lung demonstrates bronchiectasis and bullous emphysema, associated with irregular emphysema. trees show severe chronic bronchitis. All bronchial In spite of the presence of dyspnea and cough, pulmonary function tests are within normal limits, except for a decreased percentage of DLCO. In a case of carbon pneumoconiosis, the chest radiograph reveals gland glass appearance. The S.A.B. demonstrates focal emphysema or ectasia of the small air ways, suggesting the process of centrllobular emphysema. Furthermore, poor definition of alveolar pattern may be Indicative of bronchiolitis obllterance. In a case of asbestosls, the chest radiograph shows characteristic pleural thickening with abnormal pulmonary markings. calcified plaque and Increased The S.A.B. demonstrates typical bronchiolitis obllterance with no filling of alveoli, and with the presence of ectasia of the small air waysi these findings 748 are Indicltlve of pulmonary fibrosis. In a case of glass wool pneumoconiosis, the chest radiograph Is quite similar to that of asbestosis. The patient had been engaged on glass wool cutting for only two years. The S.A.B. demonstrates typical bronchiolitis obliterance and ectasia of the small air ways, findings which are more advanced than in asbestosis. According to the A.C.C.P. Committee's report, there Is no evidence of pulmonary reaction to fibre glass. The authors experience Is limited to only two cases, but structural alterations of the air conducting system in glass wool pneumoconiosis is remarkable, and this can only be shown by S.A.B. and biopsy. It is concluded that there are several methods for morphological analysis, but that the S.A.B. procedure is suitable to demonstrate the anatomy and pathology of the air-conducting systems without lung biopsy and accompanied risk. 749 Aplicación de la alveolo-broncorradiografía selectiva con ampliación 4il a la neumoconlosis. H. Snida. K. Chiyotani e Y. Saito (Japón) La alveolo-broncorradiograffa selectiva (ABS) con ampliación 4il obtenida con un tubo de rayos X equipado con un reflector focal de 50>jm de diámetro y pantalla de lantánidos constituye un procedimiento útil para demostrar los cambios radiomorfológicos en la patología de las vfas respiratorias. Los autores ,ap(lic§ron este procedimiento a 218 casos de neumoconiosis, silicosis, neumoconlosis del carbón activado, neumoconiosis de los fundidores, neumoconiosis de los soldadores, siderosis, asbestosis y neumoconiosis producida por la de vidrio. La ABS se realizó previa Inyección de 1 a 3 mi de sustancia de contraste (de ácido 3 acetllaraino-2-4-6triiodo benzoico) administrada mediante un catéter de angiografía (KIFA núm. 7). El catéter se introdujo fácilmente en el decimocuarto bronquio. La ABS demostró i a) en sistemas centrilobular o panacinar, en los casos de silicosis y de neumoconiosis de los fundidores; b) enfisema focal o estasis de los conductos en la neumoconiosis del carbón activado y en la neumoconiosis de los soldadores i y c) también estasis de los conductos con obstrucción de los bronquiolos en la neumoconiosis provocada por la de vidrio. Las comprobaciones no contradijeron las clasificaciones histológicas (Gough, Heard, Heppeleston, Wyatt y Sano). La broncorradiograffa convencional era insuficiente para demostrar con exactitud los cambios morfológicos en 75o las vías respiratorias. El enfisema pulmonar o estasis que no se observa en la radiografía habitual de tórax se visualiza claramente con este sistema, que muestra el desorden estructural sin necesidad de efectuar una biopsia pulmonar y sin riesgo. 751 I f ~¡ I r r I K.Ronock and "i : ' r , I r- t, f [v U.Teichprt Tpchniques, Strategies and results of" dust «onsurompnts In the asbestos industries. II P.H.Conner., J.C.Day., C.A.Kennedy. , H.C.Lewinsohn Dust control in a conventional asbestos textile factory III Progress In the control oF asbestos dust in the u/ork place Alex A. Cross. IV Graham W.Gibbs Thp envioonmentel data basa Tor prevention studies in Quebec V A.SchOtz Protection against quartz and asbestos dust exposures at workplaces VI 9.Carton., E.Kauffer., J.C.Vigneron et m.Villi Efficacité des masques antipoussleres Vis-A-Vts de liAmiante comparaisons des différentes techniques de de comptage des fibres d'amiante. TT A.Dogoumols Cas d'application de le convention de 1 ' oit(NM39)sur le Cancer professionnel, 1.974, en relation avec le flocage a l'amiante dos structures métalliques et des tuyauteries d'un immeuble en construction a Geneve. 753 Vth INTERNATIONAL CONFERENCE ON PNEUMOCONIOSIS ILO Caracas / Venezuela 29.10 - 3.11.1978 Techniques. Strategies and Results of Dust Measurements In the Asbestos Industries K. Ronock and U. Telchert. Oust Measurement Advisory Panel, Asbestos International Association (AIA) Asbestos fibre concentrations In the working environment are generally determined by the membrane filter method, developed and Introduced by the Asbestosls Research Council (U.K.), but experience has shown that the technique does not always produce comparable results. Differences can arise due to va- riations in sampling, preparation of slides, optical counting, and the calculation of the results. International comparison and epidemiological studies are meaningful and feasible only If agreement can be reached concerning all details of the method. Furthermore, differences due to specific conditions and therefore different risk factors have to be associated with the various fields of the asbestos producing and asbestos processing Industries. These are not to be generalized for Instance for the spray Insulation Industry, textile Industry, asbestos mines and mills, the asbestos cement Industry and the users of asbestos containing products. Values of past dust situations without any dust control In these various branches, reported by different authors and measured by ourselves, are presented In Figure 1, using a logarithmic scale for the fibre concentrations per ml. The 2 fibres per ml value Is marked by a dotted line. 755 The maximum concentration In the general environment Is also included In this flguret The variation scope for average fibre concentrations Is marked by crossed lines, short-term peak concentrations are marked by darts. By controlled handling of asbestos and application of the most recent technical dust suppression methods we have now achieved dust concentrations equal to or below 2 fibres per ml. This means concentrations up to 3 orders of magnitude less than we had in the past or, in other words, from several hundreds up to more than thousand fibres per ml In the past down to 2 fibres per ml and below. The maximum concentration of the general environment, however, Is by 2 orders of magnitude (factor 100), below this 2 fibres per ml value with a maximum of 0.05 fibre per ml. The use of gravimetric units (nanogram per m ) with concentrations of 1 up to 1000 nanogram 3 per m sounds very high for the general environment, but Is regardless of the biologically important fibre dimensions. For a rough estimâtIoni 0.05 fibre per ml are equal to 2500 ng per 3 3 m or In the other way, 100 ng per m are equal to 0.002 fibre per ml. Additional physical and physico-chemical investigations (fibre dimensions, elastic properties, surface adsorption properties, foreign substances in the raw asbestos) are necessary to detect those properties representing a health risk on its own or in connection with other factors (smoking habits). Only when these results are available and found to be In accordance with extensive medical findings, will re-conslderation of the threshold limit value via dose-response or concentrâtIon- 756 response-relationship be possible and objectively and well founded. Till then asbestos dust exposure at workplaces has to be kept as low as feasible through effective technical measures. Dr. R. Murray (U.K.), a former officer to ILO, created last week a new definition! That we all are archaelogists in this field of industrial hygiene when we try to explain the medical findings to-day by past dust situations. On Initiative of the Executive Committee of the Asbestos International Association (AIA) It is intended to follow up the "Counting Trial" (on behalf of the International Agency for Research on Cancer of the WHO, Lyon 1972) which took place 4 years ago under H. Walton (Edinburgh) and G. Glbbs (Montreal) and with the participation of 9 countries. The aim at that time was to find out the differences which may occur at light-microscopic counting of membrane filter samples of asbestos dust. At a first Inter- national Colloquium on Dust Measuring Technique and Strategy in Warmensteinach (Germany), August 1977, with 39 participants from government, academies and industries of 15 countries, organized by the Wirtschaftsverband Asbestzement (Germany),on behalf of the AIA, we discussed for the first time the whole set of problems connected with the way of sampling and evaluation. Final aim of this and a following meeting should be to achieve International standardization of technique, strategy and evaluation of measurements at the workplaces and thus to come to an overall uniformity for determination of person-related dust exposure. At a second International Colloquium 3 weeks ago (October, 1978) In Washington, organized 757. by the Asbestos Information Association of North America on behalf of the AIA, the established "Dust Measurement Advisory Panel", of the AIA under the chairmanship of myself presented a "Reference Membrane Filter Method for the Determination of Fibre Concentration at Workplaces in the Asbestos Industry". This "reference method" set out in a detailed way in 45 pages is an attempt by the asbestos industry to reach an international accord. It is not Intended to affect national regulations but to permit international comparison of data. After presentation, introduction and discussion the 39 participants of 13 countries were asked to give their comments, suggested changes and additional remarks until 15 December this year. Additional im- provements may be included until middle of February 1979, the final Draft Proposal should be mailed end of February 1979 to all participants of the Washington Colloquium. The AIA will publish and distribute the agreed Reference Method within 4 weeks (end of March 1979) and will also hand it over to ILO and WHO as a responsible contribution of the industry In this matter. In the course of this year many measurements have been taken in the laboratories of the 7 members of the Dust Measurement Advisory Panel (from 6 countries) to approve the details of the Reference Method. a special paper. We will publish all the results in I would like to inform you about some Inter- esting facts i For the estimates of a workman's exposure, samples must be 758 taken In the operator's breathing zones, that means a hemisphere of 300 mm radius extending In front of the face, and measured from a line bisecting the ears. Exposure can be assessed by long-term sampling or by short-term sampling (describing fluctuations in the work process). Static sampling can be useful it it is shown that the dust is uniformly distributed over large areas. In view of individual working practices it Is not possible in gene ral to assume that data from one operator can be used to judge the exposure of another, even if the persons concerned are engaged in similar or even identical jobs. Any transfer of data must therefore be validated by appropriate relative measurements. The flow rate of the pump has to be determined with an Installed or external flowmeter and has to be checked at least before and after sampling (Figure 2). In case of long-term sampling the flow rate must also be checked during the sampling period. The average flow rate is used for evaluation. The sampling has to be repeated if the initial and final flow rates differ by more than + 10 %. During short-term sampling (10 - 30 minutes) the filter can be held by a technician in the breathing zone of the worker or worn by the worker (Figure 3). Static samples, i.e. samples at fixed locations, may be suitable for some control purposes but are not recommended for the measurement of workmen's exposure to asbestos dust (Figures 4 7). For continuously recording the dust concentration at a work- place at certain distances from the dust source, taking Into accou a special air flow direction the Tyndallometer (measuring scatter» 759 light, Leltz, Wetzlar) was used. Point sources cause considerable concentration gradients thus causing the results of static samples to vary considerably over short distances« However, static sampling can be useful It It is shown that the dust Is uniformly distributed over large areas. At a typical workplace of the asbestos cement Industry (punching of sheets) comparative measurements at various distances from the dust source have been made with the Tyndallometer of Leltz and the Personal Dust Sampler of Casella. With constant dust composition and distribution of fibre dimensions a good correlation was obtained (Figure 8) which is, however, not transferable to other workplaces. Here, diverging distribution of fibre diameter and fibre length may occur and thus lead to another correlation between both methods. Investigations have been conducted to test the permeability of membrane filters of 0.8 >um pore size for fibres perceptible under a light microscope (length 7-5 ;um, diameter<3yum). Three filters (SM 11304) of 140/jm thickness were placed one after the other and sampled at a flow rate of 24 1 per minute. The results (Figure 9) show that the share of fibres perceptible under the light microscope (down to a diameter of 0.3/an) penetrating the first filter Is too low to have any influence on the measuring result. Mounting the Samplet For mounting use the acetone-triacetine method only (Figure 10). All other mounting procedures will give a lower counting rate (20% and more). is the better background of the filter. 76o But the main reason for this Figure 11 shows a slide mounted with acetone vapour and trlacetlne which can be compared with Figure 12 which has been mounted with trlacetlne only. Regarding the Influence of the filter loading with fibres on the counting result, the following may be statedt Generally, during longer sampling times, loading on the filter Increases, This will Influence the measuring result. The higher the filter loading, the more difficult It Is to detect all fibres or to decide whether a fibre should be counted or not, specifically If additionally to the fibres non-fibrous particles are present. The results may be taken from Figure 13, With high filter loading (more than 5 fibres per field) the determined fibre concentration 3 per cm declines on behalf of visually lnterferring factors. This should be considered for long-term sampling. It Is Im- portant to assure always the same filter loading. There are problems arising from utilization of different graticules. pare It Is much harder and more tiring for the eye to com- the fibre with a reference size (British Standard 3625 / Figure 14) than to have an Immediate scale available (Figure 15). The latter Is a grid of 5 jum mesh length. Even so we aim to de- velop a better type of graticule for International acceptance. Last not least, graticules with mesh length of 5>um, but different total counting areas have been examined (Figure 16). For comparison we used 3 "5jum grids" with 250 jum, 175jum and 125/urn edge length and accordingly with counting areas of 0.08, 0.03 and 0.016 mm . 10 preparations with different filter 761 loading have been counted (0.1 fibre per field up to about 3 fibres per field). and triacetlne. Mounting was performed with acetone vapour On average evaluation of the grid with only 125 >um edge length was about 7OX higher than by application of the big grid of 250 um. However, the difference declines with decreasing filter loading. Apart from these examples there are additional factors (absorption of phase rings> etc.). You will have seen how essen- tial it is to standardize the membrane filter method in detail. In this respect, lacking accord may already lead to differences up to 300%. Moreover, there is the problem of how to perform sampling itself (location and sampling time) which nay lead to even greater differences up to 800Z in total« This means that the accuracy of measurements may be between 0.25 fibre per ml and 4 fibres per ml when a concentration of 1 fibre per ml is evaluated. This embraces the whole range of the present TLV of 2 fibres per ml and a proposed TLV of 0.5 fibres per ml. It also highlights the irrelevance of discussion about a TLV of 2, 1 or 0.5 fibres per ml by extrapolating from past dust situations with respect to our present technical knowledge. Of more significance is that there has been a reduction in the workplace from hundreds of fibres per ml down to few fibres per ml. Data on dust concentrations hitherto available which has been taken for epidemiological investigations may therefore only be considered as estimates. Only by close cooperation between physicians, epidemiologists and physicists and bringing together 762 of medical findings with the data of dust measurements may clarification of causal connections be achieved. Furthermore, close cooperation Is essential between all Institutions Involved In the asbestos question In order to protect workmen from health hazards. The Industry Is willing to contribute their experience on the situation at workplaces. For protection of the general environ- ment AIA Is also prepared to monitor the environmental asbestos concentration since In future the Dust Measurement Advisory Panel will be dealing with questions not only of emission from asbestos plants, but also the presence of asbestos dust In the ambient air Including electron microscopy anyway, exchange of samples and slides, training of measuring technicians, advise by establishment of measurement laboratories and organizing colloquia concerning this matter. Last not least, let me finalize by citing the Interpretation of an average or mean value, mainly used by statisticians and epidemiologists, published last week In a German Journal! When a man stands with one leg on a hot plate and with the other In ley-water than his average temperature Is very pleasant I We have to step Into a detailed description of the real personal exposure and not only to use average values. 763 Figure 11 Asbestos dust concentration (fibres/ml) In different branches of the asbestos Industry and of the general environment (dotted linei 2 fibres/ml) - logarithmic scale Fleure 2i Flow rate of 3 Personal Dust Samplers as a function of operating time Fleure 3i Fibre concentrations measured by Personal Dust Sampler worn by the worker in comparison to a Personal Dust Sampler carried by a technician Fleure 4i Disposition of 2 Tyndallometers on both sides of a dust source, taking into account the air flow direction. Fleure 5t Dust concentration recorded by Tyndallometers 1 and 2 disposition of which is depicted in Figure 4 Fleure 6> Tyndallometers 1 and 2 at different distances from a dust source, taking into account the air flow direction Figure 71 Dust concentration recorded by Tyndallometers 1 and 2 the disposition of which is depicted in Figure 6 Figure 8» Correlation between results of Tyndallometer and Personal Dust Sampler at a typical workplace of the asbestos cement Industry (punching of sheets) 7fia Figure 9i Permeability of membrane filter with 0.8 urn pore size for fibres Fleure lOi Counted fibres by application of different mounting substances Fleure 111 Slide mounted with acetone vapour and trlacetlne Fleure 121 Slide mounted with trlacetlne only Fleure 131 Influence of filter loading on the counting results Fleure 14i Gratlculei British Standard 3625 Fleure 15» Gratlculei Grid of 5 urn mesh length Fleure 161 Influence of the size of the graticule area on the counting result 765 Figure 1 Ubrmt/mi Insulation Industry i * • tulli» industry f 1 1 1 t 1 7 • • t • AC filants •k • 1 • ....j gmnmrml .„,,«**.* 7fifi Figure 2 Mourrai» [I/min] Figure 3 POS following Ihm p*rton [t/cm*] Y I.S IO r • 0.5 * • Ilttl0 motion • - • fot of motion PDS on r/w person H/cm*! 767 Figure 4 0,S - 1tQ mlsec. * • * * 73 cm «cm Et Figure 5 TM1 TM2 Figure 6 0 5- • 1.0 m/s oc. f ' f 1- 1 Wem 75cm J Figure 7 TM1 ' 769 7M2 Figure 8 Figure 9 1. filter 3.0 fibres /cm3 2. fitter 0.0 6 fibres /cm3 3. filter 0.0 7 fibres /cm3 Figure 10 counted librai M tar acel ine 100- £ Tri acalin I - Sft Tri 'cetin ft * •i h •l • a H i lohexa nom 1 • US- + o 1 r* u. h. lotta xai vous •Vap * « 5 III + 50- u Ü ï •: ÌÌ 2€ il I J 77o , F i g u r e 11 F i g u r e 12 «i 771 Figure 13 libimi / e m * manuring point 340 POS * 8 x10 min PDS 2 2x30 min 1 PDS 3 | I" 60 min ». 2 3 1.78 0.93 0.8« 27 1.04 0.90 OB 3.43 2.37 2.48 or I.OB 0.64 0.49 2e 0.21 0.17 O.fS 772 Figure 14 . * ir- Figure 15 Ï .... ^i__ _j_ 775 «— » . ............. Figure Orti ¡cul» Af « 250* 250um o 175*175 vm * 128*125 firn librm* /mm i i l l u s t 774 Îi r e » io 16 DUST CONTROL IN A CONVENTIONAL ASBESTOS TEXTILE FACTORY P. H. Cooper, J. E. Day, C. A. Kennedy, H. C. Lewinsohn Raybestos-Manhattan Industrial Products Company, North Charleston, South Carolina 29406, U.S.A. INTRODUCTION The first recommended threshold limit value (TLV) for asbestos exposure was that of Dreesen et al. of the U.S. Public Health Services. In 1938 following a survey of 5A1 employees of four North Carolina asbestos textile mills, they proposed a standard of 5 million partlcles/cublc feet (mppcf) for the prevention of asbestosls. This standard was Included In the American Conference of Governmental Industrial Hyglenlsts (ACGIH) list of maximum allowable concentration (MAC) values In 1946 and, In 1948 was placed on the ACGIH listing of TLVs. ACGIH TLVs became legally enforceable standards In 1968 for those Industries to which 2 the Walsh-Healy Act applied. The standard proposed by the British Occupational Hygiene Society In 1968 and adopted In Britain In 1970 was based upon the concept of a cumulative dose and the risk of less than 1% of exposed persons developing the earliest signs of asbestosls. This standard of 100 fiber years per cm was interpreted as mean- ing that a similar risk applied for an exposure of 2 fibers/cm3 for 50 years, 4 fibers/cm for 25 years, etc. In the United States, a federal standard of 12 fibers/cm3 775 greater than 5yu In length, 2 mppcf, was promulgated on May 20, 1969, under the provisions of the Walah-Healy Public Controls Act* This also was proposed as an Interim standard under the Occupational Safety & Health Act (1970) on May 29, 1971, but was soon replaced by an Emergency Temporary Standard of 5 f/cm on December 7, 1971. As required by the Occupational Safety & Health Act, a permanent standard for asbestos exposure was promulgated six months later in June 1972 . This standard permitted exposure to airborne concentrations of asbestos fibers, longer than 5 micrometers, provided that the 8-hour time-weighted average (TWA) concentrations to which any employee may be exposed "shall not exceed 5 fiber per cubic centimeter of air". The standard also stipulated that, effective July 1, 1976, "the 8-hour TWA airborne concentrations of asbestos fiber to which any employee may be exposed shall not exceed two fibers, longer than 5 micrometers, per cubic centimeter of air". Thus, industry knew that it had a target to obtain by July, 1976 and decisions had to be taken as to how the task of complying would be achieved. We decided that, Irrespective of the standard demanded, we would use the most effective and practicable means of reducing dust to the lowest possible level and would continue to manufacture asbestos textiles by conventional methods. In this paper we will describe the engineering methods which enabled us to achieve our target and still maintain the continuity 776 of the operation. The project was completed in July 1977. HISTORICAL DETAILS The plant, acquired by us in November 1969, was run down in the preparation-carding and weaving areas. Much work was needed to make it productive and a profitable venture. The employee union demanded certain commitments before signing over its negotiated contract to us and one of those, the development of a "safe workplace" for its membership, we readily agreed to. In 1969 approximately 87,000 cubic feet per minute (CFM) of exhaust air was collected in a baghouse and could be recycled to the workplace. Approximately 9,000 CFM of exhaust air was collect- ed in a cyclone collector exhausting to the atmosphere. The baghouse air was collected from preparation and carding. The cyclone air was collected from weaving and filling winding. There were no other areas in the plant with exhaust ventilation. Waste fiber was removed from the baghouse in open-top boxes and from the cyclone periodically by shovels. The Chrysotile asbestos fiber was brought into the plant in compressed bales. The asbestos and carrier fiber storage areas were orderly with little or no noticeable dust emission. Old-fashioned methods were used for fiber preparation, including blending, opening and mixing. The opened fiber was stored in stock-holding bins of about 3,000-4,000 pounds capacity. The pneumatic line that fed fiber to the bins did so by means of a 777 ceiling condenser mounted over a crossing conveyor belt that was located on top of the bins some 25 feet above floor level. The fiber had to be removed from the bins by hand, using a pitchfork to transfer it to a loose cart from whence it was taken to the front of the card-feed hopper and hand-fed to the carding machines. The cards were built in the late 1930's and early 1940*s. The roving from these cards• wound on wooden spools, was very weak and broke constantly. Breaks of this type contributed to the dust problem in the later spinning operation. The cards had enclosed and exhausted cylinders but were dusty due to poor design, poor upkeep and inadequacy of the extraction system. Under-card wastes were removed by a mechanical rake, delivered pneumatically to the baghouse and removed by shakedown. A portion of the waste was re-used and the rest bagged off and sold. Spinning was dusty mainly due to yarn breaks. As the end broke, it hit the adjacent ends and created dust. Twisting suffered from the same problem but to a lesser degree. Winding was done dry without exhaust ventilation and this created dust. Weaving was done dry with air extraction on some looms. Attempts at exhausting automatic looms had been unsuccessful and those fitted with wet pans were not effective because only a portion of the yarns in each type was wetted. The yarns for weaving were wound dry and the warp yarns were supplied from creels in a dry state. No dust controls had been attempted on these processes. 778 Inspection and shipping was probably the cleanest operation In the plant due to the nature of the job and there were no dust controls. The cloth and tape was wrapped In kraft paper and shipped« At the time of the plant's acquisition, dust counts were q barely below 12 f/cm (the maximum allowable concentration re- commended by the ACGIH), and the productive process was Inade- quate for a profitable venture. We recognized that the plant had potential and needed a textile facility for our friction materials plant In Pennsylvania. It was decided to convert the product line from typical asbestos textiles Into yarn and cloth for use In friction materials manufacture and to reduce dust generation where possible. The strategies to be used werei 1. Increase carding production by upgrading and reclothlng the cards, convert the tape condenser cards to ring condensers and produce a quality roving of a coarser count from all cards wound on cheeses Instead of jackspools. 2. Upgrade the raw material by using Casslar fiber In Grades A and AA and Bells 3-T, by using good long staple cotton combined with rayon and by the Introduction of a core yarn (for carrier) at the card to allow for good roving strength for spinning. 3. Change the method of spinning and twisting from ring spindles to flyer spindles. 779 4. Start a program to reduce dust generation In weaving by dampening the yarns at the loom and winding for weaving» The action plan'necessary to accomplish the above took nearly four years from 1969 - 1973. CORPORATE POLICY In 1974 we formulated a comprehensive corporate policy which included the elimination of asbestos from products where a viable substitute for it could be found» All other asbestos-containing products would be manufactured by a "clean system". Control measures were to be developed to cover the entire process from the introduction of the raw asbestos through the disposal of waste, scrap and rejected material. An intensive study was made of all asbestos and asbestoscontaining products. Products were Identified for elimination from manufacture and others were identified as candidates for manufacture under the "clean system" concept. Restructuring of the manufacturing system and capacities was then planned. In June 1975 a comprehensive "clean system" plan for asbestos textiles> requiring the expenditure of $12.3 million, was approved. It provided $2.6 million for the redesign and conversion of the conventional textile operation to a "clean system" process. The remaining $9.7 million was for a wet extrusion process plant and for the close out of yarn manufacturing at the Pennsylvania plant. STRATEGIES DEVELOPED FOR THE "CLEAN SYSTEM" PLAN In order to accomplish the objectives for the conventional 78o textile pianti the following strategies were developedi 1. Elimination of all man-handling of raw asbestos fiber by use of a closed system where possible« 2. Reduction of dust generation by effective exhausting or wetting where possible. 3. Utilization of as much of the existing equipment as possible from the Pennsylvania plant and the textile plant by relocating, rebuilding and modifying as required» 4. Upgrading an expansion of existing buildings and simplification of vacuum cleaning by having smooth walls and avoiding ledges and surfaces that catch and retain dust. 5. Provision of a maximum volume of fresh clean air to the workplace by use of heated or humidified make-up air units. 6. By design« provide for a safe, clean method of waste collection and reuse and/or removal. The action plan required nearly two years for completion, reducing fiber counts to less than 1 f/cm and increasing the plant capacity considerably, ACTION PROGRAM Plant Facility A new addition of 50,000 square feet of floor space was built 781 utilizing the "smooth surface" approach. This new floor space was designated for spinning, twisting equipment, an office and a maintenance shop/boiler room. Fresh make-up air with added heat and humidity was provided for by installing three 50,000 CFM, and one 65,000 CFM roofmounted units. These required that an additional 500 horsepower boiler be Installed giving a total boiler horsepower of 750. Additional exhaust air was provided by Installing a 110,000 CFM baghouse of the pull-through type having two 125 horsepower backward Incllded blade fans. There are ten bag-cell modules, five on each fan. Shakedown and waste removal Is accomplished by screw conveyors dumping through rotary air locks into plastic bags. air. This allows for a total of nearly 200,000 CFM of exhaust The building Is thus under a slight positive pressure. The starting and stopping of the make-up and exhaust air have to be tied together electronically to prevent damage to the building. Blending/Opening A "fiber control" blending line Is used to blend the asbestos, carrier and waste. Each feed hopper Is enclosed and under a negative pressure, opened at the feed end only so as to allow the bags of asbestos to be opened In an area draughted away from the operator and Into the hopper. The under-card waste Is returned pneumatically to Its respective feed hopper of the blend line, where the long fibers are separated from the shorts and sand, by passing through the screen of a celling condenser directly Into the hopper. 782 The hopper Is completely enclosed and exhausted. This eliminates the job of under-card fly removal once done manually. The blended stock is conveyed pneumatically to a "reserve hopper" kept under negative pressure where up to 5,000 pounds can be stored for work in process inventory, allowing blendline changes for versatility in mixes. The stock or mix is transferred pneumatically to card feeds. It has been found that air velocity of 2,000 fpm minimum will carry the mix through a ten inch diameter duct up to three hundred feet away to a card feed provided that there is no increase in duct elevation and a minimum number of turns. 4300 fpm is used to main- tain the efficiency of the system. These processes eliminated the job of "stock hauling". Carding An acceptable, high-quality roving can be produced from a single cylinder card provided the card is fed with a mix having an intimate blend, uniformly opened and made into a web having uniform density and weight. This conserves exhaust air in carding, allows for higher card loads per operator and reduces card maintenance. The feed decided upon is the CMC "EVETJFEED". cept of the feed is an air-laid web. The design con- Level control in the hopper is controlled by two photo-electric cells, a high level, and a lowlevel control. The ceiling condenser runs constantly. An air- operated damper valve is controlled by the indications of the photo cells. Low-level indication will open the damper located on the 783 clean-air side of the celling condenser, allowing fiber-laden air to pass through the condenser, and thus depositing fiber into the feed hopper of the "EVENFEED". High-level indication will close the damper, stopping the flow of fiber to that unit. It has been determined that no more than six "EVENFEEDS" can be serviced at a time due to the production capability of the fiber opening mechanisms (FOM) and amount of fiber that can be kept moving through an air duct. Thus, there are six cards to a line. Controlling the total system (six cards, six EVENFEEDS, one FOM, one reserve hopper) for one line of cards demands sophisticated electronic controls. An electronic scanning system that can scan the photo cell indications in any predetermined sequence is employed on each card line. Depending on roving count desired and production rate of the cards, the system Is scanned once every 15 to 45 seconds for hopper-level control. This allows a uniform feed to the cards. Controlling dust emission at the cards has been accomplished by double enclosing the cards and exhausting the enclosures into a baghouse, and at the same time forcing fresh make-up air from overhead ducts downward through the work alley, passing by the operator and into the enclosure opening. The function of the double enclosure is to minimize and contain dust generated by the card. The secondary enclosure surrounds the immediate card area, opening only at the front for roving removal. There are service panels that may be opened or removed for card maintenance. 784 Spinning and Twisting The spinning room has been designed to create a cross draft in the room. Fresh make-up air is brought Into the room through the celling on one side and distributed by means of a header and duct system accross the room. This allows approximately 5 air exchanges per hour with no air extraction from machinery. The spinning and twisting is done on flyer type frames, although they have had their speed reduced to minimize noise and dust (approximately 900 RPM spindle speed). and carrier core yams are used. Roving is wound on cheeses Work practices are the main contributing factor in reducing dust in this area. Winding for Sales We use mainly Foster 77 winders. The winders are enclosed and exhausted effectively, having the backs, sides and top covered, leaving a portion of the front open for operator access. Suspension of heavy, clear, plastic strips vertically in the face opening of the enclosure allows good operator access and visibility while maintaining a high-air-velocity low-volume system. Work practices In this area are also major contributing factors in achieving low dust counts. Weaving All weaving is now performed with wetted yarns. The wetting of the warp yarns is done by padding-rolls immersed in water troughs located behind the harness section of the looms. yarns are wetted in the same manner during winding. again immersed in water just prior to weaving. Filling They are A resin treat- ment is also applied at the loom in the same manner as wetting. 785 This serves to "lock In" the fibers in the woven fabric, minimizing dust generation from the fabric in later use. The weaving area has narrow fabric and heavy hand looms. Yarns manufactured by the wet dispersion process elsewhere are now being introduced in weaving in this plant and this will further insure low dust counts. Inspection and Shipping Due to the nature of the job and resin treatment applied to the cloth in weaving, dust has nearly been eliminated in inspection. The yarns are now packaged in stretch-wrapped plastic on pallets. The cloth is packaged in plastic bags and tapes are packaged in shrink-wrapped plastic. Dust has virtually been eli- minated in this area. OPERATING PRACTICES Before the implementation of engineering design and methods at the plant, it was recognized that engineering alone would not maintain a "clean system". During the construction phase, development of work practices and administrative procedures was given a high priority. When the construction phase was completed, these new practices and procedures were ready for implementation. Work Practices All employees, including supervisors and management, are expected to maintain constant attention to performance of stipulated work practices. Examples of work practices to assure the efficient operation 786 of the "clean system" arei a. Maintenance - All processes except spinning, twisting and weaving are enclosed and ventilated. Special pro- visions, such as lock-out procedures, protective clothing and equipment, and supervisory monitoring procedures have been instituted to protect personnel from excessive dust exposure during periodic and emergency maintenance situations in the enclosed operations. b. Waste Handling - These operations can easily get out of control without good work practices. Wetting methods and bagging procedures have been given priority consideration. Waste is handled by classification, such as baghouse waste, loom waste, roving waste, etc. with specific responsibility for proper handling being assigned to designated personnel. c. Baghouse Operations - These areas offer the greatest probability for spills or malfunctions to occur. At- tending personnel are required to wear protective cloth-ing and respirators when entering the hopper areas of the interior baghouses. These areas are posted, requiring authorized entry only with protective equipment. d. Clean-up Methods - Routine clean-up operations at Marshville require the use of industrial utility vacuum cleaners on a continuous basis. Special clean-ups of building overhead areas, pipes, etc. are performed by personnel wearing protective clothing and respirators. 787 e. Equipment Removal - From time to time It Is necessary to move machinery and equipment« The work practice used requires a thorough cleaning of the equipment to eliminate loose asbestos and then oiling to suppress any dust that may have escaped the cleaning process« f. Warehouse Surveillance - In the storage and moving of bagged raw asbestos fiber or packaged finished goods• tears and holes are sometimes created by handling equipment which allows the escape of airborne asbestos dust. The work practice requires the Immediate patching of all bags or containers at the time of rupture, or when discovered! and before further moving« Administrative Procedures Administrative procedures are used to supplement the engineering controls« methods and work practices and to further assure effective use of the "clean system". These procedures range from mandatory measures to optional additional personal protection for employees. The following are examples of the administrative pro- cedures used at Marshvllle. a. Protective Equipment - During any emergency situation, protective clothing Including a respirator must be worn. This Includes, for example, emergency maintenance of enclosed equipment or rupture of a pressurized fiber-carrying duct. Special clean-up crews must also use this equipment. These procedures are necessary as airborne levels of asbestos 788 dust during clean-up or emergency maintenance operations are unpredictableRespirators and dual lockers are made available to all employees regardless of how little asbestos dust exposure may occur« b. Disciplinary Enforcement - Employees are required to adhere to the work practices and procedures developed to operate the "clean system". To enforce the program graduated dis- ciplinary measures are used up to and including dismissal to emphasize and support the importance attached to carrying out the work practices. c. Clean-UP Personnel - Clean-up personnel , working continuously on each shift have been added to compliment the engineering achievements. These employees are in addition to those who performed this function prior to the engineering changes and represent more than a doubling of this effort. d. Employee Information - Achievement of a "clean system" procès stimulated a renewed effort in the employee educational program. Audiovisual instruction materials, pamphlet handouts and verbal instructions by first-line supervision are all used to re-emphasize the importance of limiting asbestos dust exposure to the lowest achievable level. e. Dust Monitoring - Monitoring of asbestos dust exposure to individuals and work area dust levels Is performed at a frequency considerably greater than Is now required 789 by che OSHA asbestos standard in view of the fact that dust levels in all areas are controlled to levels well below the permissible limits. Each month a selected number of dust samples are taken. Additionally a complete and extensive survey is accomplished annually to assure that the baseline exposure level is known. CONCLUSION The plant has approximately 150,000 square feet of floor space and employs slightly over 200 people. It has capacity for making in excess of 8,000,000 pounds of asbestos textile products and friction yarns annually. The clean-up and expansion program was completed under the forecasted budget monies and slightly over in time. Despite increased energy costs, the manufacturing cost has not increased per pound of product made. Increased produc- tivity has helped offset inflation and energy costs. The improvements in dust control can be quantified by studying the mean asbestos fiber counts in various manufacturing areas. All levels are maintained below 1 fiber/ml, 8 hour TWA. The dustiest operations have been totally enclosed or eliminated. The importance of work practices cannot be over-emphasized, Poor work practices, or carelessness in adherence to good work practices at any single operation within the plant, can result in widespread contamination and possible dust exposure. It is recognized and accepted that, although the engineering designs embarked unon have been completed, experience will determine what additional improvements can be made or need to be made. It is also roco/;,nized that operational procedures may have to be 79o modified from Cime co Cime, le is our incencion co reduce employee dusc exposure Co Che lowesc possible level achievable by reasonably oracCicable means wich che goal of providing a safe and healchy workplace. Ic is also our incencion Co concinue Co pro- duce convencional asbesCos cexciles in che knowledge chac che plane described is probably Che eleanese of ics kind. This paper also serves Co illuscrace Che difficulcies which mighc be encouncered when conduccing epidemiological studies in industry to determine dose-response relationships when Cechnical achievemencs in environmental sampling, raw material production and engineering controls undergo changes over a period of time while the process and final product remain essentially unaltered. 791 REFERENCES DREESEN, W. C , J. H. DALLAVALLE, T. I. EDWARDS, J. W. MILLER AND R. R. SAYERS. 1938, U.S. PUBLIC HEALTH BULLETIN NO. 241. 2 NICHOLSON, W. J., 1976, in Occupational Carcinogenesis. and Joseph X. Wagoner, Edsi Umberto Saffiotti Ann. N. Ï. Acad. Sci., 271, 152-169. BRITISH OCCUPATIONAL HYGIENE SOCIETY - SUBCOMMITTEE ON ASBESTOS HYGIENE STANDARDS FOR CHRYSOTILS ASBESTOS DUST. 1968. Ann. Occ. Hyg. 11: 47-69. 4 HYGIENE STANDARDS FOR AIRBORNE ASBESTOS DUST CONCENTRATIONS FOR USE WITH THE ASBESTOS REGULATIONS 1969. TECHNICAL DATA NOTE 13, DEPARTMENT OF EMPLOYMENT, H. M. FACTORY INSPECTORATE. 5 OCCUPATIONAL SAFETY AKD HEALTH ADMINISTRATION, DEPARTMENT OF LABOR, 1972. PART 1910 - OCCUPATIONAL SAFETY AND HEALTH STANDARDS. TO ASBESTOS DUST. Fed. Reg. 37: 11318. 792 STANDARD FOR EXPOSURE PROGRESS IN THE CONTROL OF ASBESTOS DUST IN THE WORK PLACE Alex A. Cross, United Kington Beginning of Control Although there had been Isolated reports of lung disease among asbestos workers In the early part of the century, there was little general awareness of an occupational hazard until the 1920s. This Is clear from the Merewether and Price report to the U.K. Factory Inspectorate In 1930 referring to the dis- covery In 1928 of "a case of non-tubercular fibrosis of the lungs in an asbestos worker of sufficient severity to necessitate treatment in hospital". Dr. Merewether's Investigations on the medical side (during the years 1928 and 1929) were considered to be of great scientific value and were said to establish that asbestosis "was the result of Inhalation of asbestos dust over a period of years and that the development of the disease varied in direct proportion to the length of the exposure". In this paper,' we are considering the development of controls for the protection of those who work with asbestos. Important though the conclusions of the medical expert are, I am referring to this report mainly to provide a starting point In our review of the extent to which progress has been made In the development of dust control for the protection of people from the risk of asbestosis. The conclusion of the report by the Chief Inspector of Factories is worth quoting in this connection. 793 "The remedy as in the case of so many industrial diseases, is in the suppression of dust". He goes on to add "In the non-textile section of the in- dustry no serious difficulties arise as regards the application of exhaust ventilation. For the textile section, it is evident that a good deal of experimental work will have to be carried out". Following this report, the U.K. Asbestos Industry Regulations were enacted in 1931, to be implemented by 1933. These were the first governmental regulations to be introduced specifically applied to work with asbestos. They reflected the primary concern with the textile side of the industry, and it was in this sector where the main efforts at the centrated. development of controls were con- A committee was set up consisting of technical experts from the leading asbestos textile manufacturers and from the govern2 ment. Their report, published in 1931 , Includes detailed designs for dust extraction equipment, and their application to all stages of asbestos manufacture, from the emptying of sacks of asbestos fibre to the weaving of asbestos cloth. on It also includes sections mattress making, recommends the preparation of a "precautionary leaflet for the guidance of workers" by the government department concerned, and even a brief reference to a method for the gravimetric determination of dust. Effectiveness of Control One has heard many stories of the obvious improvement in the atmosphere of the work place from old-timers from the industry who remembered the pre-control days. In 794 one factory it was said that for every kilowatt of power used for production machinery another kilowatt was used for dust extraction equipment. Certainly great efforts were made, but at that time and for many more years such efforts lacked any guidance as to the level of concentration of asbestos dust which could be regarded as a target. Neither at that time was there any Indication that certain specific size ranges of asbestos dust might be harmful. The U.K. Asbestos 3 Industry Regulations simply referred to "asbestos dust" and failed to define dust. In the absence of any proper definition, this was interpreted by factory inspectors, industry and employees as "no visible dust" ("visible" meaning visible to the human eye under normal working conditions). It was not until the early sixties that the experts began to suggest that health risks from asbestos arose from a certain size range of asbestos fibre Invisible to the human eye under normal lighting. Clearly the apparent elimination of visible dust was no guarantee that all harmful exposure had been avoided, though conversely observation of visible dust might be taken to indicate the presence of an invisible component. Nevertheless, the improvement in controlling the dust In the textile industry from 1933, in spite of some relaxation during the war years, was seen to be having its effect in reducing the Incidence of asbestosis to that sector by the early fifties. The progress achieved in a major asbestos textile plant can• be judged from the data included as Appendix (i) of the British Occupational Hygiene Society's publication "Hygiene Standard for Chrysotile Asbestos Dust". 4 This shows the progress achieved between 1952 and 1966 when routine dust sampling results became 795 available. There can be no doubt that dust levels tn earlier years were considerably higher, though no measurements are available. Control to a Standard The occurrence of asbestosis in the textile industry was beginning to show the benefit of improved control, but after fifteen or more years of new applications, such as sprayed insulation and the growing popularity of preformed thermal insulation, especially in war-time ship construction, it was observed that other areas of manufacture and use were in even greater need of control. As the ILO report of 1973 stated, control measures effectively applied in the factory situations were more difficult in the case of such work as lagging and insulation, in which sector, as a report by McVittie in 1965 showed , the greatest number of cases were being observed. As data accumulated and as sufficient time elapsed for evidence of a beneficial effect of sustained control to become available, as in the textile industry, it became apparent that risk was related to a combination of duration and level of exposure. Tentatively, levels of exposure were suggested which it was believed would lead to minimal risk. The passage of time provided increasing evidence of the long term effect of past measured exposure, on the basis of which threshold limit values were calculated that would provide a practical and effective standard of control. 796 Ac last management and its engineers could monitor the effect of their control measures and select the priority target for their efforts. Control engineering became a much less hit-or-miss affair and could be organised and checked in a scientific manner. Modern Aids to Effective Control Sophisticated techniques of sampling the atmosphere In the work place have been developed which helped Identify areas where concentrations of dust were greatest. A further development - the use of quartz-iodine lamps (the Tlndall Beam) - helped to pinpoint sources of dust emission responsible for or contributing to the concentrations. Thanks to the co-operation of the British Factory Inspectorate and the Asbestosls Research Council, we are able to see examples of such dust emission location using the Tlndall Beam technique. Photographs taken using the same technique also show the effect of dust control by comparing machines operating with and without dust exhaust. It must be pointed out that dust seen under the beam does not indicate the level of concentration of resplrable asbestos dusti this must be measured by one of the approved sampling techniques. The Approach to Control In seeking the most effective means of reducing risks to health by control all the available methods should be considered. These will be well known to most delegates, but recapitulation may be worthwhile. They arei 797 1. Modification of the product so that it is less likely to emit dust. 2. Elimination of the duet producing operation or process. 3 . Suppression of dust - for example, by damping. 4. Avoidance of personnel exposure by mechanisation. 5. Enclosure, usually in combination with exhaust ventilation. 6. Exhaust ventilation 7. Good factory hygiene. 8. Personal protection. (dust extraction). Personal protection is deliberately placed last. It should be regarded as the line of last resort where all other measures are impractical or insufficiently effective, such as during breakdown, emergency or maintenance operations. It must not be regard- ed as an alternative to other practical forms of control. Work Procedures Coupled with these approaches, and essential to them, is the establishment and careful observance of work practices which will contribute to the control of risk. There are many substances in common use which could be highly dangerous if not used properly, i.e. by the scrupulous observance of certain rules. In the prevention of occupational risk in the use of many asbestoscontaining products, correct work practices have been established which, conscientiously applied, prevent the possibility of harm- 798 ful dust emission. The essential requirements here are not only well thought-out methods and equipment, but sound training and effective supervision. This particularly applies to work away from static workshop conditions and facilities. Record of Progress Those who have conscientiously applied themselves to the prevention of asbestosis - and any other asbestos related disease have some reason to be proud of the extent to which their dedication has achieved such greatly improved control, especially during the last decade. It should be emphasized that until little more than ten years ago, plant engineers and managers had only the most general direction of their efforts from medical and scientific experts. With the introduction of the sampling and spotting technique referred to earlier, for the first time they were able to focus their efforts on the vital part of a machine or operation and check on the results obtained by measurement. Some idea of the progress made possible by systematic attentic to first-priority problems and by regular and consistent monitoring - "control accounting" - can be gained by the following comparisons Table anf figure 1 covers six factory locations in different parts of the U.K. and relates to three different types of product containing asbestos. The Improvement between 1971 and 1978 speaks for itself. Table 1 The second figure shows progress made in one factory in 799 Denmark between 1971 and 1975, indicated by the decrease in the number of persons whose occupation fell within the higher of the concentration groups. Conclusion Regrettably it has to be recognised that this standard of control is not universal. In most industrial countries there are now laws which require measures to be taken similar to those recommended by ILO in 1974. The responsible firms in the asbestos industry in those countries have already developed control techniques to an advanced stage and are giving a lead in many other Q states where statutory requirements have not yet been introduced. But, as with many other occupational hazards, the process of education of managers and workers to recognise and observe safe work practices is one requiring skill, experience and enormous patience and dedication. It will require the combined and co- operative efforts of government, workers and managements, and it is a prime objective of the international asbestos industry to take a responsible lead in ensuring a consistent and effective level of control for the prevention of health risks in the use of asbestos. The ILO Booklet "Asbestos Health Risks and Their Prevention" (No. 30 in ILO Occupational Safety and Health Series) first published in 1974, provides practical guidelines for the control of risk bases on a very thorough and unprejudiced review of the evidence available. Although this review is now four years old, the advice of the experts from government, trades unions and 8oo industry contained in the report is just as valid today. Indeed if all the member states of ILO had followed this advice, perhaps we should have heard less of the often emotional demands for unnecessarily extreme measures which have so confused the issue in recent years. 8o1 ^ü c\j c\j <-o c^ o ^o \Ä A CO VO VO V 0 M fe O 8o2 *$*. 8o5 i-íüUi^i '¿ '?.oo C /.'OUI IC 'S! A <0DÜ)2C0 AL EMPLOY S 0 900 ooo . 150 700 6C0 500 IOOÌ \ \ 90\ 4 CO BO\ 70\ 300 So} i / \ \ \ 1 \v / v 200 -sol 30\ 100 \ / / y-^ V \ \ \ \ \ 50\ yy > 2 F/rnl. \ A V \ s\ 20\ lo\ ñoM \ \ --"" v\ REFERENCES 1. Report on Effects of Asbestos Dust on the Lungs and Dust Suppression in the Asbestos Industry. Merewether and Price, HMSO, 1930. 2. Report on Conferences between Employers and Inspectors concerning Methods for Suppressing Dust in Asbestos Textile Factories, HMSO, 1931•• 3. Asbestos Industry Regulations 1931. 4. Hygiene Standards for Chrysotile Asbestos Dust. Hygiene Society, Pergamon Press, 1968. 5. Asbestosis in Great Britain. McVittie. Conference on Biological Effects of Asbestos.1964. 6. Control of Asbestos Dust - Technical Data Note 35. Inspectorate,1972. 7. Asbestos: Health Risks and Their Prevention. Occupational Safety and Health Series No. 30. International Labour Office, 1973. 8. The Control of Asbestos Dust - Recommended Control Procedures. Asbestos International Association, 1978. 8o5 HM Factory Inspectorate. British Occupational HM Factory THE ENVIRONMENTAL DATA BASE FOR PREVENTION STUDIES IN QUEBEC Graham W. Glbbs Occupational Health and Safety Unit, Department of Epidemiology and Health, McGlll University, Montreal, Quebec, Canada The setting of alr-quallty standards In the workplace to reduce the risks of asbestos-related diseases to levels which are acceptable to the worker and society requires a knowledge of the relationship between exposure and response. While In- dices of "health effect" are In need of refinement and standardisation to permit valid comparisons between the health experience of various occupational groups, I will restrict my discussion today to the problem of exposure assessment. The main factors Involved In the production of health effect are the quality and quantity of dust, the duration and pattern of exposure, and individual factors. By quality of dust I refer to fibre type, fibre dimensions, shape, surface characteristics, other minerals, trace, elements and organic contaminants. The quantitative aspects of exposure will be discussed later. Duration of exposure Is an Important Index of exposure, but of limited usefulness on Its own, unless the other parameters of exposure are static. The pattern of exposure (e.g. short period high v s long term low) may be Important, especially when lung clearance mechanisms might be overwhelmed. Time since first exposure Is Important, but alone does not 8o7 provide Information which can be used to prevent health effects. Individual factors and susceptibility include age, other diseases, particle clearance rates, and other host factors as well as variations in level of exposure related to work practices. The latter is of increasing importance in considerations of exposure assessment. Other agents or factors include smoking habits, general air pollution, etc. which might influence particle behaviour or effects. That all varieties of asbestos present the same level of health risks for the same level of exposure is logically unlikely. Fibre types differ chemically, mineralogically and in physical dimensions, and specific health effects do occur at different rates for persons exposed to different fibre types. In order to provide information on one variety of asbestos (chrysotile), an epidemiological investigation of the relationships between exposure and mortality, pulmonary function, symptoms and radiological changes in Quebec asbestos miners and millers was initiated by Dr. J. C. McDonald in 1966. The methods and results of these studies have been published elsewhere. However, the environmental data used in these epidemiological studies provide one example of how indices of exposure can be developed, their problems, limitations and validity. Considerations in the selection of an appropriate index of dust exposure are threefold! 1) To derive a numerical value for levels of exposure 808 which produces various risks of health effect, It is necessary to base the index on measurement of environmental conditions. Measurements of personal exposure would be ideal but are rarely available for the past. 2) The index of exposure should have a good chance of relating to the measured health effect. 3) As the health effects being measured probably result from exposures 20-30 years ago, it is necessary to be able to assess the levels of past exposure. Asbestos has been implicated in lung fibrosis, in producing increased risks of lung cancer, gastro-intestinal, and laryngeal cancers, and, except for anthophyllite, is associated with malignant mesothelioma. It is therefore quite possible for different health effects to be related to different parameters of the asbestos dusts to which workers are exposed. Indeed primary malignant meso- thelial tumours may be related to the presence of fibres of certain dimensions in the inhaled dust cloud. In the Quebec chrysotile asbestos mining industry, measurements of airborne dust were made by the same observer since the late 1940's using the midget impinger method. This method of dust measurement, which formed the basis for standards in the asbestos industry in North America for almost 30 years, is inefficient for the collection of fibres, the count being based main- ly on particles. As particles observed are essentially greater than 1.0 AM in diameter, it is likely that counts reflect the 8o9 airborne respirable mass concentration but this remains to be demonstrated. Although some counts of fibres using the midget impinger were made in the past, the low efficiency of the impinger for fibres at the time of the Initial studies forced us to rely on the particle counts in million particles per cubic feet. As measurements were made at some mills before dust controls were installed, they provided a useful bench mark for assessment of earlier levels of exposure in the industry. Based on the midget impinger measurements, discussions with older employees and management, dates of ventilation improvements and process changes, we constructed a table of dust levels for each area in which workers might be employed. From a description of the time spent in various locations, we derived for each job, for each year since the industry began in 1878 an index of dust exposure. Using the work history records for each employee (some 28,000) taking account of the Job and hours of work, we calculated for each worker a dust index expressed as the product of exposure time and dust concentration for all jobs on which men had worked. We also calculated dust indices weighted for physical effort, physical application and weighted by the time that the dust had been able to act on the lung. Some of the limitations in the data were as follows i Dust surveys were conducted at irregular intervals. Individual work practices may have permitted exposure above or below the ambient concentrations. While the conditions under which the surveys were conducted were reasonably well documented, the measurements were not made primarily for health studies, but for 81 o evaluation of environmental quality. The irapinger samples were collected over relatively short periods (10 minutes), and the lmpinger is known to be inefficient for the collection of fibres. It was necessary to assess levels in periods prior to measurements being made. Nevertheless, the patterns of dustiness as recorded by the midget lmpinger coincided with the known level of environmental control and provided a useful data base for the establishment of an index of exposure. The validity of an exposure index is checked by its ability to predict health effects. In the study of mortality of Quebec miners and millers, the relative risk of death from respiratory cancer showed an extremely good relationship to dust exposure level. In the case of radiological changes, the age-standardised prevalence of irregular small opacities (1/0 or more), in workers in one mining area (Thetford Mines) showed a gradient with dust exposure, but the highest correlation coefficient was only 0.27. In the other asbestos mining area there did not appear to be any meaningful relationship. The weighted indices produced only minor improvements in correlations with some abnormalities. In a longitudinal study Liddell et al., also found that associations between radiological responses and measures of asbestos exposure were weak. Whether this is due to an inappropriate index of exposure, individual differences in level of exposure or susceptibility factors is not known. Breathlessness related reasonably well to the dust index, and certain pulmonary function changes were also sensible related to exposure. 811 It therefore appears that the dust index based on midget impinger measurements reflects in some way the parameters related to increased risk of mortality from lung cancer among Quebec chrysotile mines« Environmental standards for asbestos are now almost universally based on fibre counts using the membrane filter method* is also so in the Quebec asbestos mines and mills. This It was there- fore important to examine the relationships between fibre exposure and indices of health in that industry to determine the validity of using fibre counts for the prevention of asbestos-related disease. A study is now underway to examine the relationships between mortality from mesothelioma, lung cancer, gastro-intestinal tumours, cancer of the larynx, penunoconiosis and fibre exposure as measured by the membrane filter method. We are also examining the relationships between radiological outcome and fibre exposure. This presents a special difficulty as the membrane filter method was not introduced until the 1970s and no single conversion factor was found between midger impinger and membrane-filter fibre counts for the Quebec mills. We have therefore compiled all fibre measu- rements and midget impinger measurements with a view to determining appropriate conversion factors for certain work areas and in conjunction with environmental control data and midget impinger counts to assess past fibre exposures. The case control approach permits us to work with a relatively small number of persons (1500) from whom we have checked occupational histories, and to examine exposures for each individual. 812 In some instances, past dust measurements do not exist. Another approach to the assessment of past exposures has been used in a study of employees in a textile manufacturing plant. In order to assess the past exposure of employees we asked five members of management and five employees with long services in the industry to rank on scale 0-9 the relative dustiness of the environment in the workplace at 5 year intervals since the plant began production. These rankings were performed independently. There was reasonably good agreement when conditions were dusty but poorer agreement for more recent conditions. In order to get an idea of what the various categories might mean in terms of fibre concentration we conducted environmental surveys at the plant. We then attempted to relate the categories of dust exposure with the measurements of fibre for the various locations and found that for the first 3 categories the actual measured airborne fibre concentrations were not too different from one another, but that measure ments of fibre concentration did increase in a meaningful way for the next two categories. As there were no present-day operations ranker as category 6 or greater, we do not know what these concentrations were. However, the main interest Is the health risks for persons exposed at the lower end of the scale as it is recognised that health risks are elevated In high exposure situations. Although the rating of exposures by workers is subjective, backed up by environmental survey to check actual airborne fibre concentrations, such an approach may be useful In some situations. In conclusion studies in the Quebec Mining and Milling Industry have shown that indices of dust exposure based on the midget im- 813 plnger can relate well to lung cancer mortality and demonstrate clearly exposure-response relationships. Whether membrane filter counts relate as well remains to be demonstrated. may improve the prediction (symptoms and function). Fibre counts of radiological and other changes For the studies of the Incidence of radiological changes, more detail concerning individual differences in exposure will be necessary before reaching conclusions that "individual susceptibility" Is the main rason for poor relationships with exposure. The relationships between exposure and res- ponse In the Quebec asbestos mining Industry may not be extrapolatable to other work environments where fibre type, associated dusts and fibre characteristics may be different. The Quebec study has Indicated that a single Index may not satisfactorily relate to all health effects. There Is a need for uniformity In the measurement and recording of environmental data and a critical evaluation of the Indices used In epidemiological studies. In- vestigators should be encouraged to examine other. Indices of dust exposure In parallel with those based on the membrane filter method. The validity of the dust or fibre Index should be evaluated on Its ability to predict health effects and to reduce health risks. This should not be overlooked In providing the environ- mental data base for future epidemiological surveillance or studies of asbestos-exposed workers. 814 PROTECTION AGAINST QUARTZ AND ASBESTOS DUST EXPOSURES AT WORKPLACES Regulations and Guidelines in the Federal Republic of Germany A. Schütz Dust Research Institute of the Central Association of Industrial Injuries Insurance Institutes, Bonn, Federal Republic of Germany Among occupational diseases, the lung conditions silicosis and asbestosis, caused by quartz and asbestos dusts, are still widespread. Asbestos dust is also capable of provoking carci- noma and mesothelioma. Table 1 shows the development of these diseases in the Federal Republic of Germany since 1950. The number of silicosis and silicotuberculosis cases has continuous ly decreased since theni at present their number is only about one sixth of the cases compensated in 1950. The total number of asbestosis cases is essentially lowerj since 1950, however, an increasing trend can be noted. Particularly, the number of cases of lung cancer and mesothelioma due to asbestos dust has increased. Table li Annually compensated cases of occupational diseases caused by quartz and asbestos dust Year 1950 1960 1965 1970 1972 1975 1976 1977 Quartz Fine Dust Silicosi s Silicotuberculosis 6616 3791 2416 1295 1272 1088 976 1052 924 454 393 227 256 221 184 155 Asbestos Fine Dust Asbestosis Lung Cancer+ Mesothelioma 5 23 47 63 77 75 87 62 815 . 3 2 7 15 20 26 In order to protect employees against quartz and asbestos dust, extensive regulations and guidelines have been established in the Federal Republic of Germany. They apply to every factory handling materials containing quartz or asbestos that may release fine dust. 1. The following regulations are the most importanti Enlisting of factories and exposed employees Every factory handling materials containing asbestos or more than 2% of quartz is obliged to inform the authority responsible for occupational health. This information is not required if the treatment of these materials does not induce dust production. For the purpose of enlisting factories and exposed employees handling asbestos a central office was established by the Industrial Injuries Insurance Institutes. According to the present survey about 50,000 persons from about 5,000 factories are exposed to asbestos dust in the Federal Republic of Germany. 2. Measurement and evaluation of dust exposure Table 2 shows the currently admissible limit values for quartz and asbestos fine dust. Concentrations of respirable dust are restricted to a total value of 4,0 mg/m at workplaces where the fine dust includes quartz or asbestos proportions. The 3 quartz fine dust concentration must not exceed 0,15 mg/m i for the asbestos modifications chrysotile and amosite the value must 3 be below 0,10 mg/m . Besides, the asbestos fibre concentration 3 must not be above 2 f/cm . 816 Table 2i Threshold limits for quartz and asbestos Material Threshold limit rag/m3 Quartz fine dust Asbestos fine dust (Chrysotlle, amoslte) Fine dust (In total) (f/cm 3 ) + ) 0,15 0,10 4,0 2,0 ' fibre length> 5jura and fibre diameter < 3 /jm Measurements of the fine-dust mass concentration of quartz and asbestos are carried out at workplaces by means of special dust sampling equipment and subsequent radiographic or lnfraredspectrographlc analysis In laboratories« Assessments are made by comparison between measuring results and the corresponding allowable threshold limits* In order to obtain uniform information regard- ing the question of exceeding or falling short of limit values, criteria for sampling and analysis, employee exposure monitoring programs, and statistical evaluation of the measuring results were established in a guideline by the Industrial Injuries Insurance Institutes. For example, this guideline includes instructions regarding sampler position, frequency and duration of the required measurements as well as confidence Intervals for random samples. 3. Medical surveillance The employer is obliged to provide medical surveillance for each employee exposed to quartz or asbestos dust. Exemptions from this obligation are only possible if it has been ascertained 817 by special measurement techniques or medical surveillance tests that there are no health risks» The extent of the medical sur- veillance was fixed in a guideline of the Industrial Injuries Insurance Institutes. - One has to distinguish betweeni Pre-employment medical examinations i They should be carried our before employment starts» The employer is allowed to en- gage an employee only If no objections against employment are raised by the physician. - Periodic medical examinations i They are to be performed at maximum intervals of 3 years. In particular cases these in- tervals may be shortened (or prolonged) if this appears necessary because of the employee's physical condition or exposure conditions. Follow-up medical examinations i They are carried out only in case of asbestos exposure after termination of exposure at five years' Intervals. 4. Substitutes for asbestos and quartz Within the framework of preventive measures the prime question is the replacement of quartz or asbestos-containing materials by less harmful substances, of course. According to the existing regulations and codes of practice it has to be checked always whether substitutes are available. In several cases this could be achieved by intensified efforts. - Some examples arei blasting agents, polishing and grinding materials, moulding sands which are free from quartz or have proportions. 818 only low quartz Insulating and filter materials free from asbestos. In the Federal Republic of Germany the use of quartz sand for blasting has been prohibited. At present, certain restrictions for the use of asbestos are discussed by experts in the European Community. 5. Technical and personal protective measures According to the existing regulations and guidelines the following order of priority for preventive measures has to be observed« change of process to prevent dust occurrence at workplaces or non-employment in critical areas (e.g. wet instead of dry processing, automatisation). installation of devices on dust producing machines and equipment to avoid dust spread at workplaces (e .g. complete enclosure of equipment and operation under negative pressure, complete dust exhaustion at the source) ventilation of the entire work room or workplace, use of dusttight cabins use of respirators (filter or closed-circuit breathing aparatus) As respirators always mean an additional strain for the wearer they can In general only be used for short periods of time and for special purposes like repair work. They must not replace technical prevention measures. There are special regulations for exhaust air contaminated by quartz or asbestos dust. This air has to be sufficiently cleanee and eliminated in a manner that excludes health hazards. Each re- circulation of cleaned air into the work rooms for processing or 819 energy-saving reasons requires a permission. Permission is grant- ed if It is proved that the fine dust concentration of the return q air is below 0,1 mg/m . 6. Checking of protective devices Devices which are used frequently and in large numbers for the protection against quartz and asbestos dust require type testing. This kind of testing is performed fort small dust collectors attached to machines as independent units which return the cleaned exhaust air directly to work rooms i - mobile vacuum cleaners and vacuum sweepers particularly used for floor cleaningi respirators. The requirements to be met for these devices are fixed in special guidelines. For instance, the filter material used in fine dust collectors must show a filtering efficiency of>99% for the use in factories handling quartz and>99,5% for factories handling asbestos« 2 hour by 1 m Besides, the air quantity to be cleaned per 3 filter surface is limited to 120 m . Certain insti- tutes, e.g. the Oust Research Institute, are authorized to perform these tests. The approved devices are provided with a test certificate and are particularly recommended for the use in factories. Conclusion The present regulations and guidelines applicable in the Federal Republic of Germany for the protection against quartz 82o and asbestos dust have primarily been elaborated by the Industri. Injuries Insurance Institutes! Their application in the field is controlled by the Technical Inspection Service of the Industrial Injuries Insurance Institutes. The Dust Research In- stitute has the task of developing dust measuring and evaluation methods, of carrying out measurements, of advising plants about protective measures and of checking protective equipment. 821 References (1) Verordnung zur Änderung der 7. BerufskrankheitenVerordnung. 8. Dez. 1976, Bundesgesetzblatt I, S. 3329/3337 (2) Geschäfts- und Rechnungsberichte der gewerblichen Berufsgenossenschaften für das Jahr 1977 (3) Unfallverhütungsvorschrift VBG 119 "Schutz gegen gesundheitsgefährlichen mineralischen Staub" vom 1.4.1973 (4) Verordnung über gefährliche Arbeitsstoffe vom 8.9.1975 (5) Regeln zur Messung und Beurteilung gesundheitsgefährlicher mineralischer Stäube (ZU 1/561). Herausgegeben vom Hauptverband der gewerblichen Berufsgenossenschaften (1977), Carl Heymanns Verlag, Köln (6) Berufsgenossenschaftliche Grundsätze für arbeitsmedizinische Vorsorgeuntersuchungen. Herausgeber: Hauptverband der gewerblichen Berufsgenossenschaften, Bonn; A.W. Gentner Verlag, Stuttgart (7) Atemschutzmerkblatt ZH 1/134. Carl Heymanns Verlag, Köln (8) Einrichtungen zum Abscheiden gesundheitsgefährlicher Stäube mit Rückführung der Reinluft in die Arbeitsräume. ZH 1/487, Herausgeber: Hauptverband der gewerblichen Berufsgenossenschaften (1973), Carl Heymanns Verlag, Köln P?2. IX/6 EFFICACITE DCS MASQUES ANTIP0IJ3SIERES VIS-A-VIS DE L'AflIANTE COMPARAISONS'DES DIFFERENTES TECHMIDIIES DE COMPTAGE DFS FIBRES D'AMIANTE B. CARTON. E. KAUFFER, 3.C. VIGNERON st fi. VILLA I.N.R.S. Vandoeuvre - lea - Nancy France. 1.- INTRODUCTION En France une norme AFNOR (NF S 76-101 et 201) décrit les caractéristiques minimales des demi-masques antipoussieres: efficacité* mesurée au bleu de méthylène meilleure que 85%, colmatage meilleur que 400 mg de silice a 1 mbar et pertes de charges inspiratoires et sxpiratolres inférieures (a quatre débits de mesure) a certeines limites. A intervalles réguliers, une campagne de mesure de la conformité des modeles commercialise'*en FRANCE est faite par l'INRS. Ainsi en 1976 sur 71 modeles testés, 27 étaient conformas a la norme. Il a paru intéressant, compte tenu du danger particulier des poussières d'amiante, de compléter ces mesures par une évaluation de la permeance aux fibres d'amiante. La mesure a été faite dans deux atmospheres industrielles. 2.- METHODE DE MESURE 2.1 Le montage Trois prélèvements sont faits simultanément a 1,50m du sol: 823 - un orélevement d'ambiance selon la méthode l/min classique associant le ROTHEROE MITCHELL régla a 2 l/min et la filtre MILLIPuRE 0,8 pm; - deux prélèvements sur chacune des deux tetes. On fixe de facon Stanche le demi-masque étudiéjl'air filtré par le masque est refiltrô par un filtre SART0- RIUS 0,8 pm, la débit ast continu. Chaque masure est répétée deux fois dans des conditions identiques. Les trois surfaces de filtration (deux mas- ques et la filtre d'ambiance) sont aussi proches l'une de l'autre qu'il est possible. 2.2 Ambiance La premiara série a été faite dans l'atelier des dalles d'une entreprise fabriquant du revêtement de sol. L'amiante utilisé est le Chrysotils, la moyenne des Concansa trations mesurées est de 1,25 fibre /cm avec un écart type de 0,5 fibre/cm . La deuxième série a été faite dans un atelier d'une autre société du même type que la précédente.La encore le chrysolite est utilisé; la moyenne des concentrations mesurées est de 1,25 fibre/cm avec un écart type de 0,5 fibre/cm . 2.3 Choix des débitas On a renroupé les modeles de facon que les vitesses frontales de nassane de l'air sur le médium filtrant soient aussi peu dispersées Q U O possible et comparables a celles de l'essai au bleu de methylene. L'essai dure 30 minutes (tableau 1 ) . Lo volume d'air passant a travers le masque est de plusieurs metres cubes. 824 3 • -p.ETEnniNATION PES^KRfíZMCZS, Elle passe par la mesure de la concentration C n initiale et de la concentration C. derrière le masque. La permeance est le rapport CQ/C., complément a 1 de l'efficacité. On peut évaluer CQ et C. soit par microscopie optique a contraste de phase après transparisation, soit par microscopie électronique (balayage ou transmission). On a donc mesura plusieurs permeances: - une permeance "optique" ou C„ et C, sont évaluées par comptage en microscopie optique (n„n) des fibres de longueur supérieure à 5 pm; une permeance "microscope électronique a balayaqe" (n___) ou C-, et C, sont évaluées au P1EB a un grossissement de 500 "fraticule" de même surface qu'en microscopie optique et en comptant les fibres de longueur supérieure a 5 pm; - une permeance "microscope électronique a transmission" par comptage sur photographie de toutes les fibres (n „p.- totale). Dans ce dernier cas on compte les fibriles élémentaires si elles ont une longueur suffi* sante da l'ordre du micrometre). (suite tableau No.l) 825 Tableau 1 - MODELES TESTES SURFACE (cm 2 ) 270 415 450 5D0 530 530 560 600 710 760 760 104 0 530 | VITESSE (cm/s) PERMEANCE AU BLEU DE METHYLENE ~~7T~ 7 2,4 0,5 0,3 0,3 2,1 0,4 0,9 1,5 6,6 3,7 0,5 5,0 7,6 7 6 6 5,5 5 5 4 4 4 3 5 44 33 20 14 16 11 11 4 4 4 2 2 27 30 50 77 64 <U 100 250 250 270 4500 50 -J. 4,6 2,3 0,7 4,7 2,0 1,9 1,5 14,9 2,0 2,4 0,3 0,3 . 826 MEDIUM FILTRANT i Ì 1 . , . papier épais épais papier papier épais papier plissé feutre papier épais papier épais papier plissé papier plissé papier plissé papier plissa papier piissé foutre matériau ouaté matériau ouaté matériau ouaté matériau ouaté matériau ouaté feutre J feutre ! panier épais j panier épais i papier épais ! papier épais i napier plissé _, i ; ', ¡ ! ; ! ; j 4.- MODELES TRAITES CG sont les modeles conformes en 1976 aux normes AFNOR n'ont J'efficacité mesurée au bleu de méthylène est dont meilleure que 855?. Au total, 22 media filtrants ont été testés dans deux entreprises. Chaque essai a été doublé. La liste des modeles av/ec le numéro de code correspondant finure dans le tableau 1. 5..- RESULTATS 5.1 Remarque préliminaire L'exploitation des essais n'a été maná« a bien qu'après passage au four a ozone. L'ensemble dea filtres SARTORIOS situés derrière les masquas afits'calciné at le comptage par microscopie optique s'est révélé comparable au comptage par microscopie a baleyaqe ce qui est normal pour la mame catégorie d'objetä comptés et le même protocole de comptage. 5.2 Permeance ; fibres de longueur supérieure a 5 pu Dans la grande majorité des cas, la permeance optique est tres proche de la permeance mesurée au microscope à balayage, les moyennes sur l'ensemble des mesures sont comparables. On peut donc calculer une permeance moyenne exprimée en pourcentage de fibres de lonnueur supérieure a 5 pm traversant le médium filtrant qui est faible, en général inférieure a 1 #. 82? 5.3 Permeance :_ toutes fibres Apres calcination, on a compta avant et apres la masque le nnmhre de fibres présentes, quels que soient leur longueur et leur diamètre. Une fibre est un objet de rapport lonnueur sur diamètre au moins égal a trois, on a compté sur photographia les fibrilles élémentaires de longueur supérieure a 1 pm (photonraphie prise a 660 et agrandie 4 fois). Les résultats figurent sur le tableau II, la permeance mesurée de cette facon est supérieure a la permeance mesurée en comptant les fibres de longueur supérieure a 5 pm de fa^on significative. 6.- DISCUSSION 6.1 La cohérence entre les deux séries de mesures est acceptable pour tous les types de comptage. U v a trois exceptions (numéros 20 - 12 et 64) ou les résultats d'une série a l'autre sont tres différents; il est possible que les chiffre élevés soient dus a une mauvaise étancheité du masque. Dans trois cas, la mesure a été faite sur petit et nrand support : les résultats obtenus sont en bon accord: De nlus len numéros 51 et 49 sont constitues du mame matériau filtrant; la encore les résultats sont en bon accord. 828 T^biocM te^ PprmCnncea on ! . o u r c n n t e r e F I _..... .„:.;.; , ¿ X . ' . . ^ Í L ; ; „ ¡(fOiEfri.. ;|C (li: t01li.C£. it.". 111'! (CnHi¡)t.¿'.';a-3 d¡:s f¡l)rea¿L > 'Spa ) _._ ......... Ho^-crmr Penili:..;: ¡.ptlq'w x 500 HEB x 500 0,3 s - O.í 0,25 - 0,5 0.2. - 0.5 0,3 - 1,64 M 0.85 1,0 -.1,2 1.7 -0,4 0,8 - 0,-1 1.6 - 2,85 - 0,1 1,65 • 0,3 - 0,9 0,35 - 0 . 3 0.5 ITOR IUS o 0.4 PL roi-ünnce 61 ce i.¡ on i iy.it; MF.T î.i - o,(.r. 1,1 - 0,1!. 0,75 1.9 - Ò,55 0,3 - Ì.0 0,6 -.0,5 0.6 0.9 -0.7 .t'0.6' * 1.3 - 0,< O.b 0.9 - 0,4 f» •- 0.5 4 0.25 - 1,1 0,85 - % V • 0.4 - 0 . 2 3,0 -1,1 5.9 - 0,î 2,6 10,2 - 0,35 • 0,55 - 0,1 0,6 - 0,î 0,4 . 0,7 - 0,3 Gran •o M - ».« 1,3 - 0,9 1,3 1.4 - 2,15 0,5 - 1.6 - 1,5 1,5 1.4 - 2,3 0,8 - 1.6 - 1.2 1.5 2,7 - 4.1 5.1 . «•° 8,9 -20,9 1,2 -0,9 0,8 - 1,0 1.0 1,8 - 7,4 0,3 - 0.4 0,3 - 4,1 1.4 0,5 - 7,2 2,1 - 7,2 0,6 - 0,6 2,6 1,6 - 0,6 6,8 5.8 - I,S V 7.6 - 2,3 4,? 3,9 - /;> 3,3 4.9 -0,7 3 •iX\-v.^'[ '':/'.'T.* rut ras Si m E o s •o VI ce o i,0 mr Pat Ita fil trai «1 • '3 .IA.... . . .':? 0,3 0,6 -0,3 2.1 0.9 0.2 -0*5 9,6 0,9 - 0',t 0,9 -0,6 0,C 1.4 - 0,7 »•*.:.',; 1,8 - 1,2 0,85 - î , 3 5 •-. ° « 4 ' • 0,7 2.0 1 -7 1 1,1 1.6 "' 1.15 2,¡"< i • i • 1.3 1.5,--/; .1 1,6 ' - f ^ 1 : * apraa c a l c i n â t Ion _-* 829 i •1 y ^ !•)' 6.2 Si on porte par exemple la moyenne n des permeances mesurée (fibres rie lonnueur supérieure a 5 pm) en fonction de la vitesse frontale da passaqe de l'air a travers le medium filtrant : on s'aperçoit que la permeance a tendancB a croître quand la vitesse de filtration, a debit égal, est la plus faible. 6.3 Les permeances mesurées sont nettement inférieures aux permeances mesurées au bleu de méthylène. Neuf modelas sur 10 ont une permeance inférieure a 2%, ce qui vaut dire qu'ils ne laissent passar que 2 fibres sur IDO de lonqueur supérieure a 5 pm au maximum. PTBS de un modele sur 2 a une permeance "toutes fibres" inférieure a 2 #. CONCLUSIONS On a mesuré la permeance des media filtrants conforme a la norme A FM PR. Le résultat est exprimé en % du nombre dn fibres. Aucune mesure de la perte de charge, n'a été" faite. L'essai est comparable à l'essai au bleu de méthylène prévu par la norme AFNOR pour ce qui est des vitesses de filtration. La permeance mesuran aux fibres d'amiante est plus fnible nue la permeance mesurée au bleu de methylene. On peut dire nue les masques conformes a la norme NFS 76-2P1 arrêtent au moins 95 fibres rie lonnueur supérieure a 5 nm sur 1PP. Il n'y a pas d'autre liaison entre l'efficacité a l'amiante et l'efficacité au bleu de methylene. La tres bnnne efficacité mesurée ne fait pas de ce moyen rie protection individuelle la nanacée. L'étanchRité au visant: midinern desriemi-masquRn(le projet rie norme du Comité européen de normalisation autorise 5'', de fuite) ne permet pas rie les recommander nnur le travail dans des 83o ambiances nolluécs par l'amianto mnme si l'efficacité du médium filtrant sembla tras bonne, flieux vaudrait dann ces conditions utiliser des masoues a adduction d'air ou a ventilation assistée. Las résultats obtenus sont valables oour le Chrysotils. Pour les fibres plus rinides (verre ou amosita), on peut s'attendre a des résultats comparables. 831 IX/7 CAS D ' A P P L I C A T I ™ D E LA C O N V E N T I O N OE L'CJIT ( M O . 139) LE C A N C E R P R O F E S S I O N N E L , 1 9 7 4 , EN R E L A T I O N A V E C SUR LE F L O C A G E A L ' A M I A N T E D E S S T R U C T U R E S NFTALLIOIIES E T D E S T U Y A U T E R I E S D'UN I N N E U B L E EN C O N S T R U C T I O N A G E N E V E Dirscteur de l'Office d'inspection du travail de la République et Canton de Geneue, Suisse. A. Degoumois 1ère étape - 1968 - Construction de l'immeuble de la télévision SuU_SB_ fran£ai_se à jGeneve. Projection d'amiante sur la charpente métalliaue et les tuyauteries de chauffane, ventilation et eaux (prévention contre les incendies). - Plainte des voisins de l'immeuble en construction qui constatent que des poussières d'amiante (duvets) se déposent sur les rebords dBS fenêtres et pénètrent a l'intérieur des locaux d'habitation et de travail. Intervention de l'inspection du travail qui s'adresse à: l'inspection de la construction pour que la projection d'amiante s'accompaqne d'une aspiration des poussières a la source. la caisse de sécurité sociale pour faire porter aux travailleurs exposés aux poussières des masques de protection. 2eme étape - jna_rs_ 1978 - Les occupants de 1 ' immeuble tel évision constatent la présence de duvets d'amiante derrière les radiateurs des locauj» de t r a v a il, en partie climatisés. Plainte déposée a l'inspection du travail et traitée oar un inspecteur du travail, docteur on physique et spécialiste 833 des problemas de toxiques et de poussières. - L'inspecteur prélevé des duvets d'amiante et les fait analyser par le laboratoire de toxicologie industrielle. - Résultat de l'analyse: crocidolite (amiante bleu). Quantitativement, la valeur maximale admise de 2 fibres/cm-' lors d'un prélèvement d'air n'est pas atteinte: Décision de l'inspecteur du travail : Exige de la direction de la télévision >uisse - Française (employeur), sur la base des articles 50 et SS de la Loi sur le travail et de la convention 139 de l'OIT, et cela, bien que la valeur limité ne soit pas atteinte: - Le nettoyage complet de tous les locaux de travail, étage par étage. - L'enlèvement du revêtement d'amiante sur les poutres métalliques et les tuyauteries qui peuvent entrer en contact avec l'air respiré par les travailleurs ou le recouvrement de l'amiante par une peinture de fixation, innifune, de longue durée de résistance. Copie de la décision est adressé aux syndicats des travailleurs. 3eme étape - juin 1978 - Réaction du directeur de l'inspection du travail et de l'entreprise. - Réaction du directeur de l'inspection qui s'assure, pour sauvegarder les dispositions du secret administratif (article 41LT) que les svndicets ne réunissent que des travailleurs de l'entreprise, ce qui est le cas. 834 - Réaction de l'entreprise qui convoaue une conférence a laquelle assistent: l'inspection du travail (directeur et médecin-inspecteur) des spécialistes de toxicoloaie industrielle des spécialistes de l'association Suisse des fabri- cants de produits a base d'amiante - la direction de l'entreprise Lors de cette séance, le directeur de l'inspection du travail soutient totalement la décision de l'inspecteur du travail, ajoutant qu'il n'a aucune crainte relative a un recours de droit public contre cette décision. £5J!Le- étape - Décision de 1*entreprise L'entreprise renonce a recourir et assume ses responsabilités face aux exiqences de l'inspection du travail. - Elle procede immédiatement au nettoyaoe complet des locaux. Elle étudie présentement la meilleure solution pour éliminer le risque de désaqrôqation du revêtement d'amiante. - L'inspection du travail se met au service de l'entreprise pour effectuer des mesures de quantité d'atniante sur les lieux de travail. coût de l'opération évalué a 1/2 million de francs suisses 5eme étape - Information des travailleurs Selon l'article 4 de la convention No.139, les travailleurs qui sont ou qui furent en contact avec une substance concériqene doivent recevoir une information sur les conséquences qui peuvent résulter de cette contamination. 835 Si l'on peut, sans difficulté, donner cette information aux travailleurs de l'immeuble de la télévision, le problème est plus difficile pour les travailleurs qui durant les années 1967 et 1966 se trouvaient sur le chantier en contact avec les poussières d'amiante. L'inspecteur du travail est actuellement occupé a obtenir la liste des entreprises qui ont construit l'immeuble pour connaître les noms de leurs travailleurs a l'époque de la construction et signaler a ces dernière qu'ils ont été en contect avec un produit cancérigène. La question que l'on peut cependant se poser est la suivante : Est-ce qu'il conviant, après que dix ans ont passé depuis cette exposition a l'amiante, de renseigner les travailleurs du chantier de construction de3 risques qu'ils courant? 836 I N D T C C X. I. S r e; s T n **' X D.Ascarrunz , Rappor t.Bur X. I I V.V.Tkatchev. Two-stage gravimetric method of dust concentration measurement and its application In ore mines. X. Ill C.flmoudru Problèmes méthodologiques actuales de la lutte contre les Pneumoconioses dans les charbonnages français X. IV N.'dlles., F.Falrclouçih Thu prevention and prevalence of Pneumoconiosis im nei» south wales coal mlnlnq X. V V.S.Nikitin Modern methods of dust control in oßen-pit mines in the Soviet Union. 837 CONTROL Y SUPRESIÓN DE POLVO EN MINAS Ing: Douglas Ascarrunz Eduardo. Dirección General de Higiene y Seguridad Ocupacional. Ministerio de Trabajo y Desarrollo Laboral. La Paz - Bolivia. ANTECEDENTES Desde luego que las altas incidencias de silicosis, que se presentan en la mineria boliviana no son justificables desde ningún punto de vista. Sin embargo, se impone una explicación, porque es inconcebible que no se tomen medidas más drásticas p¿ ra reducir el impacto de esta enfermedad. Como historia, diríamos que,es posible que la silicosis se manifestaba ya durante el Imperio de los Incas, sin. embargo no se tienen citas específicas a éste respecto, lo.que indica que no era un fenómeno muy aparente, máximo cuando se sabe que los incas tenían una actitud muy avanzada, en lo que hoy se denomina Salud Ocupacional. Se sabe, por ejemplo, que .al enterarse de que la explotación de las minas de sinabrio suponía un riesgo probado, se prohibió la explotación de éstas. También se sabe que los incas compensaban el servicio en minas con privilegios especiales, por ejemplo, se distribuía coca entre los mineros para ayudarles a sobrellevar el rudo trabajo en regiones de gran elevación y bajas'temperaturas. La coca, sabemos, estaba reservada a los nobles y altos funcionarios del gobierno imperi al. La conquista española trabajo un incremento descomunal en el laboreo de minas y el sistema de encomiendas que en principio no suponía un regimen de abuso; pues conformaba hábilmente con los sistemas incaicos de servicio gratuito al gobierno y sil ponía solo un servicio de 5 años de trabajo en minas; se convirtió en un sistema de explotación inhumano en manos de los aventureros que se instalaron en el Nuevo Mundo como propietarios de minas. 839 Posteriormente en las denuncias que hicieron de éste siste ma los propios españoles, no se menciona especificamente como un problema la enfermedad que deviene de respirar polvo. Es muy posible que los problemas de seguridad así como otnos abusos re legaban la silicosis a un plano secundario. Por ejemplo, I03 servicios de encomienda.debían durar solo 5 años, sin. embargo, se dilataban mañosamente hasta el doble o triple de éste período. En algunos casos los turnos de trabajo se extendían por semanas enteras en que los mineros vivián bajo tierra. Tal situación es explicable que relegue la silicosis a un plano secundario. .Además, la expectancia de vida de la época debió ser b a s tante baja de modo que la silicosis no-llegó.a. ser un impacto disernible en la población minera de la época. La República trajo la abolición de la encomienda y por ende los abusos a que ésta.daba lugar. Además, como la mano de obra dejó de ser gratuita, por primera vez se empezó a aplicar métodos más eficaces de explotación minera, empero, el problema de la silicosis tampoco se destacó, posiblemente porque las cori diciones generales cambiaban muy paulatinamente. En realidad, el problema en Bolivia no se hizo aparente hasta que la expectancia de vida hubo experimentado un inerea¡eii to y los métodos de minería sufrieran un notable cambio con la introducción de los métodosrieumáticos,de perforación, incre-mentando de éste modo el riesgo silicógeno. De ésta época datan las primeras menciones del "mal de mina." cuya presencia se va haciendo más importante con el paso del tiempo. En la época de la segunda guerra mundial las exigencias de producción llevaron a investigar las razones.del bajo rendimien. to del minero boliviano y se identifican las condiciones de higiene y seguridad como factores predominantes. Desde entonces se emprenden los trabajos que permitirían puntualizar el p r o blema. 840 Como la silicosis no es una enfermedad.deformante o particularmente dolorosa, es en realidad un estado con el que es relativamente fácil de vivir. Tampoco es la silicosis una enfermée dad mortal, sino que más bien acorta la vida natural, no se han extremado acciones preventivas como ha ocurrido con otras enfer medades. ESTABLECIMIENTO DE CONTROLES Las acciones de prevención se fijaron desde.un principio en el método más expedito, menos costoso y relativamente simple. La distribución de mascaras contra el polvo, en el caso, de Boli via. Estas eran particularmente inaprepiadas, pues a las defic¿ encias por demás conocidas, debe añadirse el hecho de que la re sistencia que causa en la respiración la hace inútil a gran ele vación. No obstante, ésta era la única acción preventiva estatuida en los primeros años de la nacionalización de la gran mi« neria boliviana. El principio de abatir polvo y ventilar minas es el objeti vo de la empresa minera estatal (COMIBOL), pues ésta es la única forma efectiva de reducir el polvo silicógeno. Este objetivo tiene limitaciones generalmente de orden económico. El estado al hacerse cargo de minas con gran desarrollo en las que no se contemplo la ventilación forzada, encontró que debía hacer grandes inversiones que no podían pagarse bajo las condiciones imperantes. Muchas de las minas de Comibol son marginales y se las mantiene en trabajo solo por razones sociales. La presión para ventilar las minas en escala integral es cada vez más fuerte y proviene del sector técnico, laboral, seguro social e incluso de las autoridades de gobierno. 841 Los logros alcanzados hasta ahora son muy dispares y van ligados a la economía de la empresa, así también como la del trabajador. Este último punto merece una explicación. Las minas que explotan minerales de alta ley manejan volúmenes menores de carga produciendo menos polvo, pero lo más importante es que pagan mejor a sus trabajadores y éstos es-tan dispuestos a usar como única medida de "protección., la mas cara, ya que un sistema de ventilación integral vendría de he cho a disminuir sus ganancias. Resulta entonces que cuando una mina mejora sus leyes los incentivos para mejorar la protección del ambiente disminuyen en la misma proporción. Por otro lado la explotación de filones de baja ley requieren ma^ yor movimiento de carga con el inconveniente de que las ganan cias son reducidas, en éste caso el trabajador insiste y pro^ mueve el sistema de ventilación integral, porque no tiene mucho que perder y por otra parte la ventilación integral la permite mover mayores volúmenes de carga para poder compensar sus bajas ganancias. Tal es el caso de la explotación en block caving en la mina Siglo XX, en la que a insistencia de las trabajadores se instaló el primer sistema de ventilación forzada en Comibol. Como se presentan las cosas en el momento actual, la veri tilación forzada tiene que imponerse aunque en forma paulatina y desigual, pues en algunas minas, la preparación de éstas ya incluía un sistema integral de ventilación como ocurre con mina Matilde que es una de las instalaciones mas modernas de Comibol. La mayor parte de las minas de Comibol dependen de la ventilación natural, es decir se aprovechan las depresiones naturales que existen entre sus comunicaciones al exterior. Este es un sistema limitado e inflexible. La tendencia actual es optimizar estos sistemas y tratar en lo posible de estable cer la ventilación forzada donde pueda ser financiada. Esto se manifiesta en una de las conclusiones del último seminario gerencial minero de Comibol. 842 En'el desarrollo de la minería en general se distinguen tres etapas en la lucha contra la neuraoconiosis. Primero, se trabaja sin conocer el efecto que tiene el polvo contra la salud. Segundo, se detecta la causa y se emprunue un reconocimien. to del problema y una evaluación de ambientes riesgosos. Tercj; ro, se procede a establecer controles sistemáticos. La segunda etapa suele ser la más larga y ésto se debe g¿ neralmente a que la supresión del polvo y la ventilación integral significan inversiones de importancia que debemos asegurarnos que la mina pueda pagar. En la empresa privada esto se reduce a una cuestión conta ble. En la empresa minera pública de Bolivia, las minas sin ejn bargo pueden trabajar a pérdida durante largos periodos ya que su cierre significaría un problema social mayor al de la silicosis. Se puede decir que Bolivia esta francamente en el camimo de intensificar controles de silicosis en todas sus formas de explotación minera, ya sea pública, privada o en cooperativas. Todos están concientes de ésta necesidad y esto se demuestra en las evaluaciones epidemiológicas más recientes que acusan niveles inferiores a los anteriores. MEDIDAS DE CONTROL DE POLVO Una de las primeras medidas, que se establecieron exitosa mente como control dé la producción de polvo fué la prohibición de perforar en seco. La práctica de perforar en seco se prohibió def initivameri te en el Reglamento Básico de Higiene y Seguridad Industrial promulgado en 1951, Pero anterior a ésta fecha, muchas de las minas grandes ya no perforaban en seco por propia iniciativa, sin embargo hasta 1965 se podían encontrar situaciones en las que se contravenía esa disposición. Hoy podemos decir que las 843 contravenciones a ésta disposición son muy raras y ocurren scio en minas muy chicas y por cortos períodos de tiempo. La práctica de la perforación en húmedo es la primera med¿ da de control de silicosis que se puede decir que se ha impuesto en la minería boliviana en forma exitosa y definitiva. Hasta el presente se sabe que el agua es el mejor medio de abatir el polvo en su lugar de origen. Pero, la mejor forma de usarla es una cuestión que depende de su disponibilidad, del efecto que pueda tener en los estratos de la mina, en el traspoi* te de carga y aún en el tratamiento metalúrgico del mineral; por tanto su uso en la supresión del polvo se convierte en un problema técnico de bastante sofisticación. La práctica actual en Bolivia, en aquellas minas que dispjj nen de abundante agua, se reduce a mojar la carga quebrada, esto impide la resuspensión del polvo acentado, pero no tiene mucho efecto en el polvo en suspensión que es el que verdaderameri te importa. En diferentes épocas se han descrito y propuesto muchas formas de usar el agua para abatir el polvo, estas propuestas van desde la dosificación de detergentes, el variado diseño de atomizadores de agua, el uso de vapor de agua, la disposición de grandes bolsas de polietileno llenas de agua cerca de los lu gares de disparo, de modo que la expansión subdita de los gases se encargue de atomizarla y dispersarla conjuntamente con la nu be de polvo. En Bolivia no se ha practicado estos sistemas, porque sus ventajas nunca se probaron a satisfacción o porque requerían planificación técnica que resultaba poco práctica su generaliza. ción. 844 El uso del agua, donde se puede usarla, no esta racionalizado y se reduce a instalar aspersores que no siempre son los apropiados, porque suprimen el polvo visible, es decir, el de gran tamaño de partícula y no. aatuan sobre el polvo de pequeño tamaño de partícula, creando así una falsa seguridad. Consecueri eia de éste factor es la recomendación enfática de no usar lava dores de airé, que en algunas épocas se veía en algunas minas de Bolivia y que hoy se han descartado. A través de la larga experiencia que se tiene evaluando ajn bientes polvorientos en minas, se ha podido descubrir que cuando las condiciones de humedad del ambiente están en el punto de rocío o muy cerca de éste, el polvo es suspensión es notablemeri te reducido, en ocasiones, hasta podría decirse inexistente. EJJ ta premisa se cumple independientemente de la temperatura ambieri te y la elevación de la mina. VENTILACIÓN La ventilación tiene la enorme ventaja sobre la supresión del polvo con agua de que su control puede ser más grosero, la ventilación arrastra con todos los tamaños de polvo y por tanto no se corre el riesgo de producir situaciones de falsa seguridad, con la facilidad con que se producen en el abatimiento con agua. En la ventilación de minas en Bolivia los primeros ventiladores se instalaron en mina Pulacayo desde la segunda década de este siglo. El uso se debía, sin embargo, a las altas temperaturas que existían en las zonas de trabajo más que al control de silicosis. La utilización de ventiladores de tamaño pequeño, nunca mayores a los 20.000 pies cúbicos por minuto se precticaba exclus^ vamente en minas con problemas de calor. 845 La mina Siglo XX fué la primera en usar ventiladores para reducir el polvo en el trabajo de block caving. En e-ste aspecto cabe mencionar también que la empresa pri vada fué pionera en la instalación de ventilación forzada. Por ejemplo, Mina Matilde fué la primera mina grande dotada de un sistema integral de ventilación forzada, antes de producirse su reversion al estado. En- Mina Chojlla se instalaron ventila« dores que contribuían al flujo natural de aire en forma muy efectiva, y ésta es una mina privada. La característica principal de la ventilación minera en Bolivia, al iniciarse esta práctica, es que no se dimensionaban técnicamente los ventiladores para los problemas existentes y a menudo se pecaba por exceso o defecto. En Siglo XX, por ejemplo, se usaron los ventiladores que sobraron cuando se cerro mina Pulacayo. Hoy se tiende a racionalizar la técnica de la ventilación poro por las razones anotadas al principio de esta síntesis su implantación es muy len ta. PROBLEMAS ESPECIALES DE LAS MEDIDAS DE CONTROL La experiencia acumulada hasta ahora permite vislumbrar, un efecto sinergético de la gran elevación sobre los factores silicógenos, ésto tal vez no se debe a la gran elevación como tal, sino al efecto de baja humedad relativa que reina en la generalidad de los ambientes de gran elevación. Las instituciones dedicadas a la investigación de estos problemas tienen gran interés en descubrir y puntualizar los factores responsables de la notable incidencia de silicosis en la minería boliviana. Desgraciadamente el accionar es siempre lento y limitado a la disponibilidad de fondos para este estudio. 846 A manera de ejemplo a continuación anotamos una serie de recomendaciones dadas a una empresa minera de tamaño grande, que son producto de un trabajo de evaluación de sus condiciones y ambiente de trabajo: a) Debe estudiarse los sistemas de preparación de cabos, de ataque de taladros y/o de voladura de minerales a fin de re ducir el actual consumo de explosivos a cantidades que fluctúen entre 0.5 - 1.0 libras/TMS. Con tal fin deberá llevarse un control estricto del consumo, para evitar peligros en las labo res vecinas la sustracción de este material por parte del personal, la generación innecesaria de gases, polvos producidos y la pontecialidad de accidentes. b) Debe racionalizarse la obligatoriedad del empleo de a.gua en la perforación para-cualquier actividad minera que gene re polvo, las máquinas perforadoras deberán contar en sus sistemas de agua, con presiones mayores de tres (3) kilogramos/ centímetro cuadrado de sección hueca del barreno y una cantl-dad minima de 0.5 litros por segundo. Debe educarseli personal en iniciar la perforación en húmedo. Esta recomendación está relacionada con el mayor riesgo y mayor número de perforistas y ayudantes encontrados enfermos. c) Debe racionalizarse la obligatoriedad de emplear agua en las operaciones de remoción, carguío, transporte y descarga de material a fin de precipitar in situ gases y polvo remanentes, atrapados. Esta recomendación está relacionada con el mayor riesgo y elevado número de otras actividades con población afectadas, (ver cuadro N°. 12). 847 Con tal fin, deben instalarse además, atomizadores hidroneumáticos en todos los puntos de generación de polvo. d) Las recomendaciones B y C tienen de por sí, alta prioridad de ejecución inmediata en razón del alto contenido de ai. lice libre encontrado en la roca madre (37»3Í)¡ la medida geométrica del diámetro de las partículas (1.35 micrones), todas ellas inhalables y generadoras de silicosis. e) Lo señalado en la recomendación D, aunadas a las condì ciones gaseosas del aire ambiente producidas por un déficit de ventilación de los lugares de trabajo, hace imperiosa la necesidad de instalar un ventilador principal del tipo axial de 100.000 pies cúbicos/minuto de capacidad, para reducir las cori diciones riesgosas imperantes. Debido a que volúmenes sustanciales de aire se pierden en parajes abondonados tales lugares deberán sellarse hermética— mente como medidas coadyuvantes a fin de hacer más efectivo lo propuesto líneas arriba. En la continuación de trabajos de desarrollo en frentes ciegos deberá instalar ventiladores auxiliares axiales de unos 3.000 pies cúbicos/minuto, que venzan una presión de ocho(8) pulgadas de agua, y con motores de ocho (8) caballos de fuerza. El aire fresco deberá ser conducido a todo frente de trabajo, por medio de mangas de ventilación. Las características de estos sistemas auxiliares están contempladas dentro del Informe. Se deberá capacitar adecuadamente una cuadrilla de ventilación, compuesta cuando menos, de cinco (5) personas. Para que el personal de interior mina no deteriore el equipo instalado, deberá cambiarse la denominación del "Bono de Riesgo" por el de "Bono de Mantenimiento de Equipo". 848 Con el fin de iniciar los estudios preliminares de venti lación el Departamento de Seguridad deberá desarrollar cuatro aforos de ventilación natural(Marzo-Junio-Septiembre-Diciem-«í bre), a fin de evaluar la influencia de las estaciones en la ventilación de interior mina. La información recolectada se vaciará en planos de ventilación. f) El Departamento de Seguridad no cuenta con personal suficiente para desarrollar acciones inherentes a la actividad, lo que le impide cumplir con sus funciones; efectuar acciones de Higiene Industrial Minera, desarrollar normas de S¿ guridad y Control; de Capacitación de Personal y Promoción de la Seguridad; de Protección de Planta; y de Prevención de Per didas; con tal fin es conveniente dotar a dicho Departamento con personal profesional dedicado a tiempo completo en el desarrollo de las acciones señaladas en este inciso para el logro de sus fines. Con el objeto de mejorar la inter-comunicación de los d.i ferentes niveles, dicho personal deberá dirigir sus programas educativos de expresión oral y escrita tanto en quechua como en español. CONCLUSIONES 1.- Todo el progreso que se hace en la implantación de controles, no satisface a ninguno de los involucrados, pero tampoco surgen claras pautas para incrementar y apurar ese progreso, especialmente en el campo de la financiación de la investigación, evaluación e instalación de controles. 2.- La supresión y control de polvos en las minas requie re desarrollo de proyectos integrales, los cuales por las especiales características de los yacimientos, demandan costos altos para su ejecución. En tal virtud los organismos estatales encargados de las tareas de prevención se hallan negocian do fuentes de financiamiento blando, destinados a la compra de equipos de ventilación mecánica y otros sistemas de control. 849 Tema 1 FACTOBES MEDIÛ-AMBIENÏALBS Y SILICOSIS SM BOLIVIA Resumen El estudio en sus aspectos ambientales e s t á basado en l o s parámetros a l t i t u d i n a l e s , de temperatura, humedad r e l a t i v a , concentración de polvo y tamaño de partículas de s í l i c e , referidos a nueve empresas de l a minería e s t a t a l , privada y cooperativas. Las a l t i t u d e s van entre 2.150 y 4.800 metros S.N.H., l a s temperaturas entre 2° y 34° centígrados, una humedad r e l a t i v a entre ¿0 y 100$ y que en 1.612 muestras de polvo eilicógeno e l promedio obtenido es de 11.30 m.ppp.c. para ocho horas/día de trabajo. Se otra parte se muestra que e l CH ( c o e f i c i e n t e de riesgo) es dos veces más a l t o que e l l í m i t e permisible, con un 62.36çé d e l t o t a l de muestras que corresponden a l de partículas de s i g n i f i c a c i ó n b i o l ó g i c a . Relacionado con e s t o s hallazgos en base a estudios clínico—radiol ó g i c o s de t i p o "inasivo-eelectivo" para e l decenio 1961-1970 en 24.955 mineros se encuentra una prevalencia de 22,13$ de s i l i c o s i s y 2.28$ de silicotuberculosis. El grupo e t a r i o más afectado es e l de 40-45 años y l a s ocupaciones más expuestas en orden decreciente son l a de barretero, p e r f o r i s t a , ayudante perforiBta y p a r r i l l e r o s , con un tiempo promedio de exposición de 9 años para adquirir l a enfermedad. Para e l decenio 1971-1975 en muestra s i g n i f i c a t i v a de 6.558 mineros l o más ILamativo e s un 12.1$ de S i l i c a t i c o s y un '¿.alfa de s i l i c o t u b e r c u l o s i s con un desplazamiento al grupo e t a r i o de 50-59 anos de edad y pequeño incremento de l a s i l i c o t u b e r c u l o s i s . Un estudio de incidencia en 6.174 trabajadores (28.36$ del t o t a l de trabajadores mineros) y aplicada una muestra de s i g n i f i c a c i ó n e s t a d í s t i c a se demuestra l a incidencia en 400 casos nuevos año de neumoconioais. Complementariamente y desde e l punto de v i s t a negativo, a travéB de l a s evaluaciones de incapacidad (año 1973-1974) se aprecia una mayor f r e cuencia debida a enfermedades p r o f e s i o n a l e s , caso de l a C.N.S.S. y que representan 274 casos frente a l a s evaluaciones por incapacidad por accidentes del trabajo que representan apenas 34 c a s o s . 85o TWO-STAGE GRAVIMETRIC METHOD OF DUST CONCENTRATION MEASUREMENT AND ITS APPLICATION IN ORE MINES V. V. Tkatchev, Institute of Industrial Hygiene and Occupational Diseases, USSR Academy of Medical Sciences, Moscow, USSR In the Soviet Union the first maximum allowable concentrations (MAC) of airborne dust were proposed In the form of gravimetric Indices In 1931. During the following years new MAC levels were proposed In the form of gravimetric Indices In the course of occupational morbidity studies and experimental studies of aerosol biological effects. Therefore, during several decades the gravimetric method has been used to measure the total airborne dust concentration without preliminary Isolation of any fraction during monitoring of airborne dust In the working evlronment. In this case dust particle-size distribution Is taken Into account (mostly by microscopy and measurement of particles), but during routine measurements this Is not always done. Is carried out In two steps. At first The measurement dust Is collected on the highly effective aerosol filter made from FPP-15 material and then the filter Is weighed. At the same time It was recognized that human respiratory diseases caused by industrial dust depend not only on the duration of exposure, amount and composition, but also to a considerable extent on the mass of particles of definite size (1). It was also recognized that, In the process of respiration, coarse 851 particles and a small amount of fine particles are retained in the air passages of the respiratory system, and that only fine particles, mainly less than 7yvn in size, reach the alveoli and can be contained in alveolar air. It is considered that the first induces the development of dust bronchitis and the latter the development of pneumoconiosis, keeping in mind the biological correlation of the two. In order to have an opportunity to differen- tiate these dust effects, the airborne dust concentration should be taken into consideration. Industrial dust particle-size distribu- tion is rather changeable and depends not only on the type of dust, but also on the dust formation process, climatic conditions and many other factors. The reduction of the airborne dust concentration by various dust control measures (water spraying, fog formation, inertial dust separation, etc.) has much less influence on concentrations of fine dust. On the basis of many studies curves were elaborated distinguishing the coarse dust fraction from the fine one or, as it is called abroad, from the "respirable" (2,3,4). These curves (the most well-known are the Johannesburg and the Los-Alamos curves) are used as characteristics to make coarse dust fall out in a preseparation chamber of a precipitator sampler. In this case only the "respirable" dust is usually measured. As the result of the joint USSR-GDR scientific studies on a unified method to measure the airborne dust concentration, the Institute of Industrial Hygiene and Occupational Diseases of the USSR Academy of Medical Sciences and the Institute of Occupational 852 Medicine of the GDR Ministry of Health have developed basic standard requirements for a two-stage gravimetric method of dust concentration measurement. In 1975 the USSR Ministry of Health adopted the new "Methodological instructions on measurement of airborne dust concentrations in industrial environment". The same requirements were adopted in the German Democratic Republic as TGL 32601/01 (group 963601)i Labour hygiene, mainly fibrogenous action aerosol MAC in industrial working environment. Measurement method"¡ "Air in the industrial working environment . General sanitary and hygienic requirements". In accordance with the new Instructions it has been recommended that for the measurement of airborne dust concentrations devices or apparatus should be used which measure the bulk of the total airborne dust (general concentration according to the USSR State Standard 12. 1005-76) and differentiate between fine and coarse fractions. The fine fraction Is that part of the airborne dust mass which passes through the preliminary separator of the twostage device. This part of the dust may be retained in the alveoli in the process of a healthy human being's respiration. The coarse fraction is that part of the airborne dust mass which is isolated from the air passing through the preliminary separator and may be retained in the air passage of the respiratory system while the aerosol passes to the alveoli. The Methodological instructions on two-stage measurement do not apply to dusts containing mainly asbestos and other fibrous particles. Measurement of these dusts is performed according to the previous instructions. 853 Sampling is to be performed in existing typical occupational conditions taking into account the principal technological processes, working equipment and sources of dust emission. Airborne dust monitoring is to be conducted at the workplace, preferably in the breathing zone. The duration of sampling depends on the objectives of monitoring. When the dust concentration is measured to check whether it conforms to the MAC level or to evaluate the effectiveness of dust control measures, mean short-time (maximum one-time) dust concentrations are determined (C k ). measured to determine the If the dust concentration is dust load, an average-shift dust con- centration is measured (C d ). The periodicity of the C^ and C. measurements is fixed in the departmental instructions. The C^ measurement should last 30 minutest during this time several successive measurements can be performed. action instruments are used, discrete sampling When rapid- (not less than 5 measurements) at equal time intervals is permitted, followed by averaging of indices and indication of minimum and maximum concentrations. The time interval is to be selected in such way that C^ covers the period of the highest dust concentration in a work shift. When C . is measured during a shift, continuous sampling may be performed, or such a number of successive samplings at intervals may be carried out, in spite of discrepancies between the concentrations actually measured, would permit to obtain a statistically significant mean dust concentration. 854 When the dust con- centration Is less than 0.5 MAC, it is permissible to prolong sampling beyond the limits of one work shift in order to cover several shifts. The differentiation of dust fractions is considered to be effective if the fine fraction contains not less than 85% particles of 2 >um in size, 40-60% particles of 5>ura, and not more than 5% particles of 10 /jm (Fig- 1). This effectiveness of separation has been achieved by the ZAM-10 ordinary cyclone developed and studied in the GDR (5, 6). Contrary to impingement separators designed to make particles of more than 7AM in size to fall out in the laminar air flow, the cyclone offers the opportunity to collect and analyse coarse dust. The Methodological instructions also contain basic requirements for the analysis of dust samples, including permissible relative errors in dust sample weighing, and for the order of fibrogenous dust component identification and recording. They include basic requirements for sampling pumps and balances and refer to recommended methods for identifying fibrogenous components of dusts. It is important to note that the new instructions do not abolish the present one-stage gravimetric measurement of the total mass of airborne dust without its separation into fractions. Their introduction Into the dust monitoring practice alms at obtaining additional Information about the partlcle-slze distribution of industrial dust. At present work is being done to design and produce the corresponding apparatus. A number of basic principles of the two«tage gravimetric 855 method were adopted at the first (German Democratic Republic, Berlin, 1973) and developed at the second (People's Republic of Bulgaria, Sofia, 1976) meetings of experts from Socialist countries' Institutes of industrial hygiene and occupational diseases (7). Unlike the gravimetric method used in the USA, United Kingdom, FRG and other countries since 1970 and permitting to measure only the "respirable" fraction, the two-stage method, as it was already mentioned above, provides for simultaneous determination of the total mass of airborne dust with its corresponding differentiation. The "respirable" fraction share in the total mass of airborne dust can differ within wide limits from industry to industry. For instance, in highly mechanized stopes of coal mines it is sometimes equal to 1% (8). It is not difficult to calculate that a dust concentration of 4.0 mg/m , e.g. in FRG (coal dust standard), will correspond, with this type of measurement to a concentration of 400 mg/m when the total mass of airborne dust is measured by the one-stage gravimetric method traditional in the USSR. After development and adoption of the new measuring method, studies aimed at its perfection and at the exploration of industrial aerosols were continued in the USSR and GDR. In the Soviet Union these studies were performed in modern ore mines with different dust concentrations. In these mines, as in all others with posi- tive air and rock temperatures, a modern and highly efficient complex of dust control measures, based on the use of water and ventilation, Is applied (1). Sampling was carried out with the SPG-10 two-stage gravimetric apparatus designed and constructed in GDR. 856 The apparatus Is so calibrated that its permanent working characteristic is 3 9.5 m of air per hour. To separate fine dust a ring-shaped fibrous filter is used to which high voltage is applied through electrodes. After sampling the apparatus is disassembled and the cyclone is cleared of the dust precipitated. The filter with fine dust is specially processed to separate the dust particles from it. Both dust fractions can be studied qualitatively and quanti- tatively. Simultaneously with the SPG-10 apparatus sample collection, sampling was carried out by the traditional method based on filtering mine air through aerosol filters. Filters were located at a distance of not more than 0.5 m from the SPG-10 apparatus inlet. Besides, conimetric sampling was carried out periodically with aerosol filters, and after filter clearing with dimethylbenzene vapours the particle number and size were determined by microscopy (9). 52 two-stage dust samples and more than 300 one-stage dust samples taken with aerosol filters were collected in the mine workings. The two-stage sampling time was within the limits from 85 to 465 min. During this time several samples were collect- ed with aerosol filters at small intervals necessary to change filters. All samples were collected at workplaces after the be- ginning of mining operations (drilling, loading, dumping). When workbreaks exceeded 15 minutes (equipment breakdown, absence of cars), sampling was stopped and continued after work had been resumed. 857 m o C •H w co co •J « «S H *-> co 3 -O IX 00 co fi CM 00 00 m IT) m O CM <M r-l CM 00 rî in in CM CM «3- st "ï O Z C O •H 4-1 Ü O fi M -r< CI) 00 co 2 O 03 O <U C i X SO IX co r-l en CM m <» O r-l r-l O • r-l •X co i 2 d) a o 00 e X è H CO O CM vO sì © CM en • • en en CM CM o d d d CM 00 • • r-< 00 O c 00 r-l U c 2 u tú oo 3 <0 o m • « r-l en O d u •a o a z eu eu M •o en o CM • r* • X 00 O o m «M en o CM r-l d d d ON •* 00 CM O r-l O d CO •o cd c OtV-v C 00 ÛO.rl C c a-H •H "O Has: C0 « o 3 O C0 r-l H w M d 00 E S _i u. o c Z ~* u o u CT T. M 4> 00 C •H •O CD O > 00 3 m OS O U <?Í3 O H Z « r-l CO a < o rJ 858 4) Particle Size ( 0 = 1.0 g/cm-3), microns Fig. 1. Selection Curves of Particlest 1 - Regulated with the two-stage method, shaded zone permissible deviations 2 - Pulmonary deposition 3 - AEC penetration 4 - BMRC penetration 859 The results of the two-stage measurements are shown in Table 1. As we can see from this Table, the particle-size distribution of ore mine dust differs according to the main operations. The highest gravimetric percentage of the fine fraction in the total airborne dust was observed during ore loading in stopes. scraping it was within the limits of 77.3 - 92.3%. During In this case the high fine fraction content was evidently due to good ore moisture, efficient ventilation of the scrapers' workplace, and its remoteness from the source of dust emission. It is interesting to note the good correlation of the overall concentrations of airborne dust measured with the SPG-10 apparatus and with the AFA aerosol filters. The obtained ore mine dust samples were quantitatively analysed for free silica content according to Prof. Polezhaev's chemical method and by x-ray diffractometry. shown in Table 2. The results are It can be seen that the free silica content in the fine fraction is usually less than in the coarse fraction and in the total airborne dust. The difference can be considerable. TABLE 2 FREE SILICA CONTENT IN ORE MINE DUST Total airborne dust X 42.8 S x 13.5 Fine fraction X S x 6.0 13.6 S x 7.0 S x 3.1 The analysis of the results has also shown that the information about the particle-size distribution of ore mine dust 86o obtained with che SPG-10 apparatus differs significantly from the results obtained by conimecric measurements. The microscopic dust examination did not permit to determine essential differences In particle-size distribution during various mining operations. In conclusion it is necessary to note that the introduction of two-stage measurements into the practice of dust monitoring will permit to compare measuring results and will contribute to a further reduction of pneumoconiosis cases among workers. From our point of view the best prospects of industrial environment dust monitoring are connected with the creation, in the near future, of apparatus for three-stage gravimetric measurements of the whole airborne dust. In this case it will be necessary to distinguish between the following dust fractions i fine, coarse and gross. The first two were already mentioned above. The gross fraction Is that part of the total airborne dust which falls out in nasopharynx of a healthy human being when breathing Industrial dust. 861 REFERENCES 1. Khukhrlna, E. V., Pnevmokoniozy 1 Ih profllaktlka. Tkatchev, V.V., Moskva, -Meditsina", 1968 Meeting of experts on the preven- 2. tion and suppression of dust in mining, tunnelling and quarrying, .Geneva, December 1952» Record of proceedings. International Labour Office, Geneva, 1954. 3. Walton, W. H. Überlegungen zur Frage von Schwebestaubmessungen In britischen Kohlengruben. 4. Breuer, H. Staub 29 (1969), S.113-118 Entwicklungen zum -gravlmetrlschen Staubmessverfahren. Glückauf, 109 (1973), No. 7, S.390-395 5. Thürmer, H. Ein Vorschlag zur Kallbrlenung von zweistufigen gravlmetrlschen Staubmebgeräten. Informationen ZAG. 14.S. 14-19 6. Beck, B., Zum Stand der arbeitshygienischen Ouwe, K., Messung und Bewertung nichttoxischer Irmscher, G., Staube In der DDR - Inform. No. 14, Thürmer, H. ZAG die Ges. Arbeitshygiene DDR. Berlin 1974 862 Vorontsova, E. I., Vtoroe soveschanie spetsiallstov Tkatchev, V.V. sotsialisticheskih stran pò unlfikatsii norm i metodov Izmerenlva fibrogennoy pyli (Bolgariya, Softya, May 1976). Published In "Gigiena truda 1 professlonalnye zabolevanlya", Moskva, USSR, No.12 1976, p. 57-58 Zaburdyaev, G. S. Opredelenle dlspersnogo sostava pyll v rudnlchnoi atmosfere. Published In "Borba s slllkozom", "Nauka", Moskva, 1977, Vol. e, X, p. 141-144 VronskL, A.I., Metodlka opredelenlya zapylennostl Latushklna, V.B. vozdukha s lspolzovaniem analitichesklh aerozolnyh flltrov. Published In Metody Izuchenlya proizvodstvennoy pyll 1 zabolevaemosti pnevmokonlozami. "Medlt8lna", Leningrad, 1965, p. 10-19 863 X/3 PROBLEMES METHODOLOGIQUES ACTUELS DE LA LUTTE CONTRE LES PNEUMOCONIOSES DANS LES CHARBONNAGES FRANCAIS C. AMOUDRU Médecin Chef, Charbonnages de France, Paris, France. Lors de l'initiation d'un programme de lutte contre les pneumoconioses dans une situation d'endémie sévère, il peut suffire, d'une part, de dépister les sujets atteints pour les soustraire aux risques majeurs,d'autre part, de développer par tous les moyens la lutte contre les poussières. Puis vient un moment où il apparaît indispensable de quantifier avec précision les différents paramètres,à la fois pour définir mieux les objectifs et pour contrôler les résultats. Les principaux types de problèmes méthodologiques sont alors: - la quantification de l'endémie, - la quantification des empoussiérages, - la définition des concentrations maximales admissibles. a) La quantification de l'endémie. Deux types de statistiques sont simultanément utilisés en France: - statistiques médico-légales, - statistiques radiologiques. Le dénombrement des images radiologiques est fait en fonction de la Classification internationale BIT des U/C 1971 radiographies de pneumoconioses. Cette approche est le meilleur outil de contrôle de l'efficacité de la prévention technique, puisqu'il y a une relation statistique démontrée entre le poids des poussières retenues dans les poumons et le score radiologique. 865 Mais ce classement des images radiographiques suppose une organisation particulière de leur lecture pour assurer la fiabilitô des interprétations : - constance de la technique radiographique - lecture collégiale pour chaque grande zone de dépistage - échange interrégional et international pour assurer l'homogénéité des interprétations et éviter les dérives. Par ailleurs, on sait qu'il n'y«pas de bonne corrélation entre score radiologique et insuffisance respiratoire. Donc les enquêtes radiologiques ne suffisent pas à elles seules à représenter le vécu de la maladie. Il est donc nécessaire d'établir parallèlement la statistique des patients indemnisés selon les taux d'incapacité permanente médico-légales ne permettent pas de comparaison à l'échelon international du fait des différences de légalisation entre les différents pays, alors que ces comparaisons peuvent être réalisées pour les enquêtes radiologiques basées sur la classification BIT U/C de 1971. b) Quantification des poussière«. Les Charbonnages français ont maintenant adopté la méthode gravimétrique; l'appareil standard de prélèvement est le CPM 3 du CERCHAR; les conditions de prélèvement ont été définies et rendues obligatoires par instruction ministérielle. Les valeurs constatées sont tributaires de cet appareillage et des règles observées pour le prélèvement; elles ne sont donc pas comparables à des valeurs trouvées dans d'autres pays qui utiliseraient un autre type d'appareil et/ou une autre tactique de prélèvement. Enfin, le dosage de la silice lui-môme doit être standardisé, quelle que soit la méthode analytique employée (dlffractrométrie aux rayons X ou dosage dans l'infrarouge) et l'on doit utiliser partout le même quartz-étalon. 866 c) Quantification dee valeurs admissibles. Différente pays ont proposé des limites exprimées en mg/nr de poussières respirables en fonction de la teneur en silice libre. Or - et c'est là le point essentiel de cette brève communication - dans les houillères françaises, il est observé, depuis de nombreuses années, des niveaux d'endémie très différents suivant les exploitations, alore même que les concentrations en poussières respirables et les teneurs en quartz sont très voisines. Il existe donc une nocivité spécifique des gisements et celle-ci semblerait d'autant moindre qu'il y existe des minéraux associés contenant par exemple soit du fer, soit de l'aluminium, mais les raisons exactes de ces différences de nocivité sont encore pleines d'inconnus. Force est cependant d'admettre au moins pour les houillères françaises qu'il n'y a pas de valeur admissible unique exprimée par le seul poids des poussières en suspension et leur teneur en quartz. En attendant le résultat des recherches en cours, cherchant à mettre en évidence par la voie épidémiologique ou par la voie expérimentale les facteurs supplémentaires de nocivité ou de non-nocivité des poussières de mines en suspension, il a été considéré que l'on pouvait procéder a une évaluation globale du danger de l'«mpoussiérage propre à chaque grande unité d'exploitation : unité géographique ou unité technique, une nouvelle réglementation (1975) a donc été formulée, qui oblige l'exploitant à définir par une méthode épidémlologique et, pour chaque secteur homogène de l'exploitation, la valeur de "l'empoussiérage-seuil E o" pour lequel le risque de-pneumoconioBe est sensiblement nul en fin de carrière. En pratique, on établit les courbes successives des prevalences radiologiques en fonction du temps d'exposition au risque et pour différentes teneurs en poussières; ces courbes ôpidémiologiques sont établies pour chaque unité d'exploitation. Par le calcul, 867 on peut alors définir la valeur E qui amènerait l'incidence au niveau minimal souhaité.. Cette valeur E 0 ainsi déterminée varie suivant les Bassins de 2 mg/nr à 10 mg/m-5 (ou même plus dans certaines exploitations à risque très faible). Cette méthode a le mérite de fixer des cibles individualisées en fonction du risque local effectif. Cependand, elle nécessite, de la part des médecins et des hygiénistes industriels, un important travail de collation des données et son renouvellement périodique pour contrôler et mettre a Jour les premières propositions. D'autre part, si cette méthode est bien adaptée à des Bassins importants et anciens à risque relativement homogène, pour des raisons de technique statistique, elle pose de difficiles problèmes pour les exploitations nouvelles ou/et petites et pour celles où les risques individuels sont très diversifiés. Enfin, pas plus qu'aucune autre méthode, elle ne tient compte des facteurs personnels ou prédispositions particulières de certains travailleurs. Or, plus la prévention progresse,plus le role de sensibilités personnelles prend une place appréciable dans l'endémie résiduelle. En outre, des études récentes ont montré que des sujets ayant quitté la mine, alors qu'ils n'avaient pas d'images pneumococoniotiques, voient apparaître parfois au bout d'un très long intervalle libre des images de pneumoconiose caractérisée et évolutive. Il s'ensuit que les valeurs seuil, calculées sur le seul personnel en activité, sont probablement surestimées et qu'il faudrait pouvoir étendre les statistiques au personnel retraité pour introduire le facteur correcteur nécessaire. Mais cette proposition pose des problèmes très difficiles de mise en forme; car si on peut saisir assez exactement le nombre des pneumoconiotiques hors de l'effectif actif, la population de référence (retraités exmineurs) est pratiquement impossible à connaître avec la précision convenable. 868 Force est donc do reconnaître que les concentrations maximales admissibles telles qu'elles sont actuellement définies par la rêglamentation, ne peuvent être considérées que comme "valeurs d'essai" et qu'elles devront être corrigées au fur et à mesure de l'évolution des courbes êpidêmioloqiques. Dans un tout autre domaine qui est celui du reclassement des sujets atteints, nous constatons que l'efficacité de l'éviction du risque comme moyen de prévention de l'aggravation est très loin d'être parfait. En effet, chez les agents reclassés à la surface dans des emplois non empoussiéres, alors qu'ils présentaient des images liminaires ou discrètes (forme 1 ou 2 ) , on constate, dans un nombre de cas non négligeable, des évolutions radiologiques parfois importantes, y compris vers les formes confluentes (forme A et -f- ). L'aggravation spontanée des pneumoconioses reste donc un problème d'une extrême gravité et pour lequel nous ne possédons actuellement aucune solution. En revanche, les complications tuberculeuses autrefois gravissimes sont maintenant moins fréquentes (incidence 0,5 % contre 1 % il y a dix ans) et leur pronostic a été transformé par les antibacillaires récents. Mortelles autrefois, elles sont guéries dans 78 % des cas dans les enquêtes récentes. En résumé, on peut considérer que la situation française est actuellement la suivante: des progrès importants ont été réalisés dans le domaine de la prévention des nouveaux cas. Par exemple, dans le plus grand Bassin français qui est le plus touché par l'endémie pneumoconiotique (NORD-PAS-devCALAIS), les empoussiérages ont été diminués de 10 fois depuis 20 ans et l'incidence de 3 fois dans le même laps de temps. Cette constatation tend à valider une loi statistique précédemment établie par nos services de recherches et qui peut grossièrement se résumer ainsi: 869 si on diminue de K fois l'empoussiérage, on diminue V K la prevalence. De plus, l'âge moyen d'apparition a été sensiblement décale puisqu'il est maintenant de 50,5 ans: les formes macronodulaires sont devenues très exceptionnelles. Mais à l'inverse, l'avenir demeure inquiétant pour les pneumoconioses déjà existantes alors qu'elles restent encore nombreuses; en particulier l'incidence de la fibrose massive progressive dans cet effectif varie suivant les classes d'âge de 1 % à 11 % par an, or, nous restons encore dans l'ignorance du déterminisme de ce type dévolution qui est la cause principale de l'invalidité respiratoire et du décès. La prévention de la fibrose massive progressive et de l'insuffisance respiratoire est donc la préoccupation médicale principale, tandis que la prévention des nouveaux cas de pneumoconiose simple reste l'apanage de la prévention technique. 87o THE PREVENTION AND PREVALENCE OF PNEUMOCONIOSIS IN NEW SOUTH WALES COAL MINING N. Wiles,Chief Medical Officer, Joint Coal Board, Sydney, New South Wales, Australia F. Fairclough, Deputy Chief Mining Engineer, Joint Coal Board, Sydney, New South Wales, Australia Introduction In the last thirty years the underground coal mining Industry in New South Wales has undergone a revolution in production methods A perspective of the changes which have occurred may be gained from the following statistics for underground operations in New South Wales i Underground Production (tonnes) Number of Employees Number of Mines O.M.S. (raw tonnes per man shift overall) Year 1948 Year 1977 10,466,800 37,014,000 17,283 15,038 138 71 2.97 10.2 Coal workers pneumoconiosis, which had a substantial prevalence in the New South Wales industry 25 years ago, is no longer a major problem. Since the Joint Coal Board medical scheme be- came fully operative in 1948 no man who has entered the industry since that date! without previous dust exposure and with a clear chest x-ray has developed a disabling degree of pneumoconiosis. Table 1 shows the method of coal winning in underground mines in New South Wales. The figures are average daily production for each of the main production areas in the State. The table shows the marked alteration in mining methods and highlights 871 the importance of continuous miners as coal producing machines. Historical Review The development of dust standards and dust sampling practice in New South Wales has been very fully described by J.J. Grierson and T. M. Clark, in papers given at the First Australian Pneumoconiosis Conference held in Sydney in 1968. The Royal Commission, under Mr. Justice Davidson, reported on the Safety and Health of Workers in Coal Mines to the New South Wales Legislative Assembly in 1939. The Report recognised that certain chest conditions occurred in mineworkers after their constant exposure to high concentrations of coal dust over long periods. Methods to reduce the incidence of dust diseases were suggested in the Report. Following the recommendations of the Commission, a committee was formed to consider dust prevention and to determine a suitable standardt the first meeting of the committee was held in 1941. The committee had the standard which had been recommended by the Davidson Commission, quantitative results from New South Wales collieries and reports and results of current overseas practice to assist it in its deliberations. The First Dust Standard and Later Revisions The first dust standard was proclaimed in 1943 and followed the committee's recommendation. The increasing use of roof bolting practice used in con- junction with continuous miners created the need to drill in the stone roof which contained considerably higher concentrations 872 Tabic 1 Himion or MINING COAL - UNUIJÌCHOUND MINIS NI;W SOUTH KALIS Average Daily rrotìuclioii (tonnes) South Maitland Singleton NorthWest Newcastle West Murragorang Valley South Coast i of N.S.W. total prodn. COAL WON IIV HAND OR CRUNCHED Year 1945 Year 1950 .. at June 1957 I960 1965 1970 1975 1977 1978 9,137 1,920 1,200 462 - . f\n c< * oz. 5* — - 66.7Í1,477 1,120 933 517 740 984 1,105 2,609 1,501 723 500 895 1,458 1,153 . 81.5Í 74.1* 1,118 ^ 6S0 186 947 106 0 0 0 - - • :><•'• Sfi> 3,442 2,537 1,497 400 23 21 - 17,783 7,75S 4,539 2,826 1,764 2,463 2,25S 63.1 60.0 27.2 10.9 4.6 1.8 1.1 1-5 1.3 CONTINUOUS HINHt As at June 1945 1950 1957 I960 1965 1970 1975 1977 1978 Nil Nil 4,394 9,286 9,830 7,496 6,491 6,166 4,713 10,630 13,953 14,896 16,560 1,669 5,641 21,882 53,065 46,991 45,125 47,490 340 550 2,904 6,768 13,876 16,427 19,585 11,619 21,912 22,253 23,603 23,053 7,536 17,372 26,326* 36,669 40,359 42,278 43,353 9,545 27,957 76,730« 138,874 144,925 145,825 152,968 14.6 39.2 77.7 87.O 93.0 90.8 90.O LONGWALL As at June 1945 I95O 1957 I960 1965 1970 1975 1977 1978 r< 7.4S9 3,902 8,767 7,160 ¿ 7.4S9 3,902 S, 767 7,160 Nil Nil Nil Nil Nil 4.7 2.5 5.3 4.21 COAL WON HÏ COAL CUTTERS Tear 1945 Year 1950 As at June 1957 I960 1965 1970 1975 1977 1978 6,103 7,183 627 5S4 457 ~ - 37.5*— . 33-3Í — 1,949 2,368 1,086 457 - 14,447 15,603 10,747 7,412 3,928 3,523 4,015 18.5% 25.9% 5,450 5,239 3,818 1,562 36O 337 - * Includes mechanised longwall. ^ Included with continuous miner. 873 49.756 - 6S.9S 10,141 5,181 1,250 - 384 509 - 35,090 35,574 17,52S 10,399 5,254 3,860 36.9 39.4 53.2 49.9 17.7 6.5 3.4 2.4 2.4 of silica than the normal coal seam. The dust from this required recognition that it created an additional hazard. At this time it was being realised that only particle size of less than 5 microns was significant with retentive dust. In 1957 a new standard was proclaimed which recognised both these criteria. The physical difficulties of counting the small particles and the appreciation of the importance of gravimetric results caused a further revision of the standard in 1967 when the particle size limits were established to be 1 to 5 microns. Correlation studies made at the time of introduction of each new standard showed the new standard to be a stricter requirement than the one it replaced. As required by the Coal Mines Regulation Act which controls coal mining in New South Wales, dust sampling is carried out as a regular procedure! a brief description of the procedure is given below. The coal mines are divided into four areas. The District Mining Engineer in each area programmes the Dust Sampling Officer to sample every working place on a regular basis. Practice has shown that maintenance of dust suppression standards is influenced by the regularity of sampling and care is taken to ensure that every machine producing dust is sampled on a routine basis. A copy of the result of each individual sample is made available to the colliery, to the Department of Mines Inspector and to the District Check Inspector. Any sample which exceeds the proclaimed standard is resampled. Mining Engineers regularly visit production units and any adverse trends disclosed by 874 sampling are Investigated during these inspections. The continuing use of the Owen's dust counter and the use of a particle count standard may be criticised as being outdated. It must, however, be remembered that these form only part of the dust prevention system which Is In operation In New South Wales, the effectiveness claimed for the system Is shown later In the paper. Trials are being undertaken to find an effective gravimetric instrument suitable for application with continuous miners working in pillars. Gravimetric Instruments which measure the dust make over a known time period have been used. Attempts to fix this type of instrument to the continuous miner have proven unsuccessful. More recently trials with personal samplers have been undertaken. These Instruments have disclosed problems In variations In air flow rates and It would appear that the pumps require calibration and adjustment at frequent intervals. Dampers have been fitted to the Instruments to equalise air flow rates. There have also been problems with the selection of suitable cyclones. Tests are proceeding to find the Instrument which Is most suitable to the needs of the New South Wales Industry. Correlation tests of particle count to gravimetric standards have not been completed and will only become effective when a selection of the gravimetric sampler to be used Is finally made. The shortcomings of the Owen's dust counter are well known. However, the Instrument Is light in weight, easy to operate and has the characteristic of being able to determine high dust make levels. By Its use conditions which create high dust levels are quickly discovered. 875 Efforts can then be made to reduce or avoid these high dust levels in the mining system» feature of the instrument. This has been found to be a useful The sampling procedure using the Owen's dust counter is given in Proclamation) N.S.W. Gobernment Gazette 12th May 1967, which is appended. Standing Committee on Dust Research and Control The Joint Coal Board, with the concurrence of the Minister for Mines, established the Standing Committee in 1954. By its creation a permanent body was established which would give an oversight to all dust problems in a constantly changing Industry. It would develop expertise in dust suppression to enable it tò advise the Minister, and it provides a forum for all interests in the mining community to meet and discuss problems affecting the incidence of pneumoconiosis. The Committee is comprised of representatives of the following organisations iDepartment of Mines Division of Industrial Hygiene of the Health Commission Miners' Federation Combined Colliery Proprietors' Association Australian Coal Industry Research Laboratories Ltd. Australasian Institute of Mining and Metallurgy Joint Coal Board These are all authorities and organisations actively interested 876 In Che coal industry and particularly in research into the control of coal dust. The Joint Coal Board provides the administrative and secretarial services and facilities to permit the Committee to function effectively. In view of the Board's responsibilities with regard to dust control this close tie has been found to be most desirable. The Committee makes recommendations to the Minister for any necessary variation of the Coal Mines Regulation Act dealing with dust suppression. The Standing Committee has three sub-committees which advise it on particular areas of expertise. The function of each of these sub-committees is explained below. Medical Sub-Committee The members of the committee are medically qualified with experience of working in the medical section of the Joint Coal Board. The Chairman of the committee is the Board's Chief Medical Officer. The committee's principal task is to consider trends in pneumoconiosis prevalence in New South Wales coal miners and advise the Standing Committee on actions to be taken. Sub-Committee on Atmospheric Dust and Ventilation Reports The function of this committee Is to supervise the statistical correlation of all dust counts taken in the mines. It reports to the Standing Committee of any engineering reason which may be the cause of any count not complying with the standard. The committee supervises the monitoring of any new 877 mining system to prevent excessive dust make. Sub-Committee on Dust Counting Instruments and Size Frequency Distribution of Airborne Dust The committee advises of any developments in dust sampling instruments and sampling methods. dust sampling instruments. It supervises the testing of It is presently Involved with the trials to determine a suitable gravimetric instrument and subsequently will become involved in the correlation work to determine a gravimetric standard. Table 2 shows the Average Dust Concentrations in N.S.W. Coal Mines and is compiled from statistics available from Joint Coal Board Annual Reports. The results are given for each of the Board's four areas» commencing in 1957. The revision of the standard in 1967 had the effect of slightly increasing the later counts. The Intake dust count and Total dust count are determined by sampling, from these the Make dust count is found by subtraction. The Intake dust count is taken in a predetermined position so that it will capture the dust make from all operations which create dust on the intake side of the machine being tested. The total dust count measures the actual dust concentration at the machine being tested, the measuring point being at the known most dusty point which is usually at the operator. This count is taken to be the measure of the most dusty condition at the working place being sampled. The Make dust count is taken to be representative of the dust created by the machine at the time when the sample is taken. The statistics include the results of all places which have required resampling because of readings in excess of the standard. 878 Table 2 AVERACE DUST CONCKNTRATIQN'S N.S.W. COAL MINES Number of Particles per cubic centimetre 1 to 5 microns in size (counts taken in coal only) South Haitiana & Singleton North West Newcastle West South Coast Rurragorang Valley 37 45 97 12 26 21 21 39 46 118 18 15 10 15 75 46 69 19 33 32 25 116 70 133 54 112 74 58 0-5 0-5 0-5 1-5 1-5 1-5 1-5 microns microns microns microns # microns microns microns IOS 84 111 20 51 43 44 114 91 93 29 26 23 38 116 71 124 42 69 58 47 228 150 276 65 75 78 64 0-5 0-5 0-5 1-5 1-5 1-5 1-5 microns microns microns microns * microns microns microns 145 126 196 41 65 5" 5i 15? 135 220 54 39 34 52 189 116 199 60 102 90 72 336 237 402 121 168 145 117 0-5 0-5 0-5 1-5 1-5 1-5 1-5 microns microns microns microns * microns microns microns Intake 1957 I960 1965 1970 1975 1977 I97S Hake 1957 i960 1965 1970 1975 1977 1978 Total 1957 I960 1965 1970 1975 1977 197S * Standard changed 12.5-1967 879 In this way operations known to be dusty are sampled more frequently so that the results In the table do not attempt to show average conditions In the mines. When a particular problem arises there Is a concentration of effort to solve the problem. This effort usual- ly requires the taking of additional samples and these are Inevitably higher than normal. Therefore In some short-period com- parisons the dust count at a mine can be adversely affected by one problem area and the long-term effect on the statistics Is to raise the average result. All production seams have been sampled to determine silica levels. At any production place which is cutting stone In associa- tion with coal mining at the time when a regular sample Is being taken, the Dust Sampling Officer will also take a sample to determine the silica content. Respirators are available to all miners at all times, and miners working In conditions where associated stone Is being .cut are expected to wear respirators. Experience has shown that there are many reasons for failure to maintain the standard. The principal causes, however, are cutting In stone and mining whilst ahead of auxiliary ventilation. Efforts have been made to Increase Industry awareness of the dangers of pneumoconiosis and prevention campaigns are directed towards ultimate eradication. Booklets In which are described the dangers of dust In mines are distributed to all new entrants. Films explaining the damaging effect of pneumoconiosis are shown at medical centres to all new entrants and to mlneworkers who are attending for routine medical examinations. 880 The decrease in the prevalence of coal miners pneumoconiosis can be related to improvement in the health of miners which has resulted from better working conditions apparent in the years since the second world war. The medical scheme run by the Joint Coal Board has been operating since 1948. It followed the results and recommendations of an inquiry, established by Commissioner Davidson, into the health of coal miners conducted by Drs. Cilento and Murray, and Mines Inspector Brewster. is given. The reference of the Inquiry's Report One of its main recommendations, adopted by the Board, was a scheme that included pre-employment and medical examination of all mine workers and similar periodic checks thereafter. One of the Board's main responsibilities is the investigation and diagnosis of coal workers pneumoconiosis by the Medical Division. Prevalence studies of pneumoconiosis amongst working miners have been carried out at regular intervals since 1948, the most recent study being for the period 1973/76. The results were based on the 1971 ILO U/C International Classification, as was the previous study. The 1968 classification had been used for all the preceding studies. Table 3 I.L.O. Scale l.L.O. U/C Scale Categoi•y 0 (Z 0/- o/o Category 1 Category 2 Category 3 0/1 1/0 1/1 1/2 2/1 2/2 2/3 3/2 | 3/3 3/4 881 Table 4 shows the prevalence for 1973-76 compared with previous studies« Table 4 1957-60 1960-63 1963-65 % f % % 16 3.6 3.5 3.0 4-5 2.9 Cat. 2 or more 4.5 1.0 0.6 0.4 0.13 0.08 P.M.F. 0.7 0.02 0.01 0 0 0 Percentage of workforce examined 10 85 85 60 96 100 1948 All pneumoconiotics * 1970-73 1973-76 % » % Commencent ent of 19 71 ILO V/ C International Classification The stage has now been reached where a new worker in the coal industry will be unlikely to sustain a severe degree of pneumoconiosis in his working life time. This achievement has been made possible by the success of dust suppression measures in the coal mining industry. In 1948 only 12 percent of the work force were in mines that had water reticulated to the coal face and many of these only used a hand held hose to suppress dust. Satisfactory suppression was only found in 6 percent of the coal faces. By 1955 dust suppression measures were effective in 99 percent of the work places. The present system can be claimed to be successful. It ha9 been shown that it can alter with changing circumstances of production and that standards have led to the eradication of pneumoconiosis. The maintenance of results within the standard when using the new methods and systems of mining, and the higher 882 productive capacity machines, has been made possible by better ventilation at the face, use of greater quantities of water, and improved control of sources of dust behind the actual mining machine. The longwall system is the only exception in which one installation does not achieve the standard on a regular basis. Trials have been in progress for some time to select the gravimetric sampler which will be used in New South Wales. This presumes the acceptance of a gravimetric standard which will come in the future. The particle based standard has served the industry well, it has wide acceptance and any change in standard will have to be shown to be an improvement. The prevalence of pneumoconiosis can be shown to have been dramatically reduced, but it can also be seen clearly that constant vigilance is required to ensure a continuation of this trend. 883 References (1) Dust Sampling and Control in Coal Mines in New South Wales Part I by J. J. Crierson. (2) Dust Sampling and Control in Coal Mines in New South Wales Part II by T. M. Clark, (3) Royal Commission N.S.W. 1939Appointed to inquire into and report upon the Safety and Health of Workers in Coal Mines. (4) Coal Mines Regulation Act No. 37. (5) Report of a National Survey of the Health of Coal Miners. Canberra, Australia, 1945. Sir R. Cilento, H.M.L. Murray and D. T. Brewster. 884 v. s . HIKITTT Vico Director dol Instituto Contrai ""do Invooticadonea Olenti fiera do Soeurlund dol Tmbajo Consejo Centrnl do l o s Soviéticos (URSS) MCToros H0nsrai03 CE Sin¿lentoa EMMISACIOH cAtiTCHi>3 DE LA mais PE POLVO Ht LAS /»VIATICA, Durante loa Ultimos nfloa ol dosnrollo de lo indùstria alncra en l a URSS so realizaba principalmente ncdlnnte ci crcclcnto uao dol bono f í - elo de recurooo naturales a d o l o abierto, e l cnal resulta nflo eficaz 7 procredvo. P"ra e l oflo 1930 a trovos de Sato DtHodo co producirá on 1« Unifia Sovietica alrededor dol 75 5» del volunen total de recureoo naturnloo. El crcclnlonto de la oscnln de utilización do túcaicpo no dorna a do alta iroductivided y el peso al benofíelo do profundas enana horlzontalea colocaron frente a l a clónela 7 ln practica un nuevo problema do eran dsiifleado auaonltarlo, social, economico 7 ecologico. 8a trata do lo eliminación dol polTO de la otmooforo en la explotación de contorne, 7a quo cl equi;» que se usa es una fuente productora de polvillo. El alto contenido do polvo en lao cantero« provoca pneuBoconlosla, Influye de nanom nociva en loa trabajedorco do plantas industriales sdtundao cerea de laa con terna 7 en loa habitan tee do ¿wblndos vecinos. SI polvo acolore ci doacooto do lea piezaa que ce encuentran en contacto ( en ¡particular, Irò do notorea y coapreoorco ) 7 puedo lndicir al cose do la extracción 7 doscubrlalento. Ln inpodbiUJlad de aprovechar en l e o canteras loa mloaoo aótodoo que oc uoan en loa alnas para la lucha contra e l polvo obligaba a tosar 885 decídenos, on principio, nueva» quo tonaura en consideración las particularidades del bene l i d o a d o l o attorto y ana graa variedad da equipos 7 esquena» tecaologleoe. Adsnfto deberían da tenerse ea enante la« propiedades da loa recursos an cuesto», condlolonea aetereolOgtcas, ella« local, ate, Las Investigaciones planifloadaa y aapllaa,ea «ata eaapo, o« lia» van a cabo m la Onto» soviética dead« el aio 1996 bajo la dirección genera! dal aeadsaloo A.A. awchlaaky, por varíe« colectivo« dentificos da la Aosdeata da Oseada» y do laatltatoa da Investigado» pertenedentea a las raaaa corraspoadleatas do la Industri». En ala do 20 anos Aste personal ha reali nado sn conjunto do estados varieos y asparla«»» talea« en al eaapo do la seguridad do trabajo o» lao canteras« qaa la* cloy« l a higiene pabilo», proaloaaa do Ingsaerta, aotereologta, ete. j Loa reaultedoe do éetae Inveetlgaeloses ostia resoaldoa a» ato do 1.500 publlcacloneo, «atro loo cualea al 30 * o s t i dedicado a l a lucha coate» el polvo a» l a s oxplotadoaeo a cielo abierto. La clónela sovietica y sus aplleaelonoo prácticas, en este nueva roa» de alaorta, ha aleaaaado grandes «altos y la prioridad ds resola don de Buenos probi nasa, ea cuanto a la ellalnadon da polvo en lao cantores, porteaoea o loo Investigadores soviéticos. Los estudios en el eaapo do la higiene publie» pusieron ea e video d a las principales fuontes de tornado» da polvo en las canteras, loo valorea de eu contenido ea datiate« bases do trabajo y loa factoreo «os influyas OB Astea coneontradenca. Eotoa estudios doaoetraroa que per falte de los oedloe pare luchar contra el polvo la eontealnsdoa de la stadere re, prácticamente ea todas las basée de trabajo, pueda superar loa al* volea poraldbles. Bata contrtUnn clon pueda extenderse s todo el 886 terrl- tarla :!c Ir centers 7 r Src-ns .-Miynesntos, cu casule .ORCO ^otor-colù Tiene 'ïeafrvoroblco 0 en Ion cooos en que c l • teori'cniii-iionto do r-olvo por /orto do l o tioquinArla ooo do u.-yor In tea d'i ed. "."lovoóoo contonl:Ioo de polvo co obocrvra on Inn contcr.no do eualqulcr profundidnd, I n clusemi* Ino poco -rofunc'ao, ddndo 30 extrocn l o o ^ao vrrladoa recar- l o alnerolos. t o cantidad de polvo r e s u l t a , pnrticularxicnto, m?s a l t o cn l a o contorna dìodo oc u t i l i z a c i transporto de canlones y trabo Jan 08 quinas perforadoras, cortadoras de piedra y excavadoras potentes, Kl beneficio de l o o 9 ri do o 00 accoppila por e l saxiso dosprendlnlonto de polvo, l o o cm terno ni tue io o en s l t l o o de e l i a n seco y cnlurooo, Fa ónde Ina v e - l o c i dodo e del viento alcanzan 3 - U motros "or corundo o l papel afte i a portnnta l o Juega e l -rocoso de lcvnntn-jlcnto de -otvo, cuyo f jmaclOB sc obnervo no '-8I0 en l a s operaciones tccnolS^icaa alno durante In d i s .jrecsciSn no turni de l a roca, bo Jo l o rcclSn de nütoblca difurencios de tenders turre. .Tara suchos conteras el'contenido de polvo en l a o.t- ndsforn durante o l Invierno reculto don o t r o s vecos aha nltn que durant e e l verano. Por l o tanto Ir lucha contro e l polvo debe de e f e c t u a r - se durante todo e l P Í O , en cualquier proceca Industrial que se aeon - peflo co cu desprendlalento. too entudion tcSrlcoo y oxforlnontaloa permitieron croar una adecuada clorjificociSn de esquenas cn cuento a l a contaManddn de d i s t i n tas brocs de trabajo, de (liferentco Areno de l a centers y de ou t e r r i torio cn ta t r i . ¿ìobro In bone de é s t o s estudian so hon obtenido cxnrealonoc - n o U t i c o o que pcnsltea, oân durante l o nroyocclSn y explota c l i n de contem, dor un prondstlco ea cuanto a In contonlnoclSn ao- b l c n t a l . Loo Jotos I n i c i ó l e o prra óectoa c á l c u l o s non l o e d,'¿uicnteoj discnoirjncs ¡jcoaétrlcae de l a cantera, particulariúadoo dol e l l o s l o c a l , 887 cantidad de máquinas y equipos en funcloanmiento, Intensidad de Xa for« nación de poltro. Se han propuesto» •denla, l a s formulas que sirven para evaluar la eficacia de técnicas y aedioa para ellaiaar ol polvo» calcular la cantidad nocooarla de loa equipo»» cuyo uao peralte aoraallsar la coaposlclon del aabiente en cuanto al faotor polvo. El estudio dol fen&aeao físico déla dlfusl&n de tapnrsasa en régl•en turbulento peraltlo la elaboración de las técnicas para deteralaar e l contenido do polvo en la atadafera de locales donde están instaladaa esquinarlas do distia tos tipos, s i igual qus Isa teealcaa para evaluar la intensidad del deepreadialsnto de polvo por parto del equipo situada en la cantera« Aprovechando ésta aetodologta as ka llegado a la eoncluatoa de q«e la latonsidad del despannrfiaelnto do polvo di rente e l funelonaaiento do Isa atqulnas do perforado*» sin hacsr nao do l o s aedioe para luchar ê contra ol polvo» alcanna en laa can tersa de carbón 1.200 ng/sag» aleatras on laa cantoras ainoraleo llega a 43.000 ag/seg. La utllisaclftn do l a s inotalaclonea abaorbeatea o aodloa huaidificadorea peralto rebajar estos valorosi on la peraoracloa do posoa llegan a 60 ag/sog , para los cantoras de carbon» y hasta 250 ag/oeg en laa canteras donde se ext r a « Dinerales. Las excavadoras de un cucharon y de rotaclta en las canteras de carbi* ain la humectoelön se caractnrlaaa por intenaidndea do fonación do polvo del orden ontre W30 y 12.000 ag/ceg| en las cantoras de •Inórales éstos valores oscilan entre 100 y 800 ag/oeg. La huaeetaclAa disminuye dichos Índices hasta 1?0 - 2.000 y 60 - 300 ag/ oeg ree pes- t i vonen te. • La lntcnaldcd do formación de ;x>lvo rjuc oo produce por el tráfico RRñ do Ion caniancc volquctao sobre los corlaos naturales dentro do los conteras v r t a entro 3.000 y 15.000 aß/ceß i el trataalonto de lo ouporflcio dol camino con oodioa adecuados baja cetas concentrecionca haota 80 - 2.000 oß/oeß. Los dedntocrodores cayo productividad oo fio o ta de 1.000 tonolados por bora sin humectación se caracterizan porua Intensidad de formación de polvo corea de 350 ng/oog, mientras que pr.ra laa maquinas cortadoras do piedra ó a too intensidades occllsn entra 1M> y 1.200 mg/oeg. /l baso de estudios teóricos canflrmadoo por datos experimentales sa han propuesto las expresiones que peralten proveer las Intoned, dp de o coperados para lo formación do polvo y de ou contonldo en los lócalos dónde, Gccûn cl proyecto, deben Instalarse naovas maquinas de olta pro« ductivldod y ol equipo para beneficiar los ¡dinerales a ciclo abierto. Los investigaciones llovndoo a cabo donoatrrron que loo nótodos de huaoctr.ciSn do distintos tipos rceultan convenientoo para loo algulentos caeos do lo oxplotoclfin do conterasi perforación do pozos, trabajos con excavadoras, bulldozers, cal como en las lábaros do oxplosloD. Bañándose en condderacionoo teóricas se ha elaborado una actodolocla que peralte évoluer la humectación necesaria de la roca o del ascino Dontaflooo volado. Co ¿sta aonora so calcula lo eficiencia de 6llmlnaclfia de polvo que al mismo tiempo resulto tccnolÔglCRacnte óptima y oconòmlennento Juotlftcda. T.oe cotuiilos clúntíficos que oo hen llevado a cabo por porte do orCnnicnoB do proyecto y construcciones dieron COBO rcsultndo la olnboracidn de tAcnlcas de buaectnclfin y el dlocflo de lnotnlsciones para absorber cl polvo seco producido en los procesos do perforación. En In perforación de distinto profundidrd, ollalnnado loo redd:ioo cedíante laa S89 mezcla« coapaeotaa por al«» y ogua, loa gastos as flete altln» constltnyon ds 10 a 60 da^/sla, lo qu» dépends de la productividad do la aaqulno y de laa proplededoa ds la« rosas porfoaadaa. Bi le teaporade lavaras! cuando la temperatura ansíente eas basta £0°C bajo cero, as aplican as» ludonsa salinas i cloruro ds magnesio, clorar» ds sodi» y clorar» ds calcio. Para la ollalnaclta de polvo producido por trabajo ds explosiones en crup» os asan, antes ds efectuar la operación» principalmente tres aétodosi 1. Irrigado» del bloque a «ola» y ds l a s ftrsaa adynoeatss i 2. Baaeetadoa femada del »acino a «»lar i 3 . Baasctocloa por liar» filtrado» dal agua quo proviene de nanjas a&taada» on la onperficls dal ascino a volar. O rosadla prelininar »o afectas aediants trenes aidrsnlieo» y aaqulnaa regadoras, sayo» gastos de agua ata do 10 da* por 1 a de arsa. ai s i eaa» dohmestaeioa del aaoino a volar e l regedlo se efectoa aediante conpreoioa « filtrada» libra, satos gastos oscilan entóneos entro 20 y 200 dar por I r * rosa, segna laa propiedades ds data. Loe gaoto» de agua para la Impregnación interna son Iguales a 50 70 da3 por cada pono engendrado por l a explosion. La humectado» tomada eoa agua o con soluciones calinas, al igual que m libre OÍ trocid», adema* de eliminar el polvo durante los traba« Joo de explosion, paraît» dieainuir el desprendimiento de polvo « l a s ulteriores operaciones tecnológicas, que son perte de la extracción ds recursos naturales por el metodo a cielo abierto. Cuando estos métodos roooltan Insuficientes pnre la huaectacl&n de la naos producida al vo- lar lao rocas, o cuando dotas técnicas no se usaron en absoluto, entonces, pore bajar el contenido de jolvo durante explosiones en grupo su»- R9o le copleorso c l regadío de dicha ans« usendo treaco hidráulicos, n i q u i - noa recodoroo o instalaciones de husiectociSc f i j o s . Ectoa nisnoa nôtodos co usrn nom oreveer o l deoprendl.-d.cnfco de polvo cuando l o o r f c i z o e se beneficimi en y "»" decacnuzorse previamente por ciedlo de explosiones, a3Î COBO Ina labore3 do carca 7 durnnts c l funcionnniento do dzcovadoros bulldozers. G-iotos e s p e c í f i c o s del agua por 1 O'5 do l e roe« per- de unoo 300 ai ni ton dlsoinuir o l contonido de polvo bosta 5 - 1 3 mg/o , Poro bonerielar l a a canteros Se han dloeftado huacetndoros e n n e c i ó l e s , cuyo alcance eo de 15 - 32 raôtroo y l a productividad de unoo 200 - 390 -Jravmin, con una presión del aijun do t» ntDOsfcras. Las Boquinas rsendorno y monitores hidráulicos instalados «so*ro camiones o trenes gprmtíztm toclfin un oleruce de busec- do 30 c e t r o s , con un casto do hasta ?50 nr de agua por hora. So han dlocflndo ooquenno y equinos pora 1« hiracctnclSn do l a s capas do cortón y de t i e r r a roturada en l o s canteros, a l Igual quo técnicas que reducen l a cmtldad do polvo levantado durmte o l funcionnniento de l a Bwqulnírlo. T'ora e l l minor e l polvo iroducldo por BÄq ¡Inas que cortan p i e dra ce han elaborado i n s t a l a c i o n e s do huaectr.clfin Cuyo uso ;-eralto bajar b concontrnclones correoponSientos hootn 3 - 5 ne/a*. Para reducir e l dooprendlnicnto de nolvo en l o s caninos dentro do l a conten», proteger su revootinlento y diooinuir l o o gastos do tratamientos oe opiles» c r i o s ( cloruros de e s l c i o o s o d i o ) , colaciones que contienen eotíin o c l e s , uolitciouco de Béselos nulfctonlcohQlicos, o oaulciones de l a s nlcRos, potrfilco crudo o naeût. Con c^ictoo de cloruro de c a l c i o entre 0 . 3 - 0.7 Its W I B do s u v e r t i d o dol canino, no nlccns?, con un nolo t r o - tnalento, In eliminación de polvo por un Intervalo do .? a h rilo o. El t r n toalonto con coluclonos quo contienen e l 30?! do cloruro do c a l c i o o aozcla 891 oulfatoalcohdlica .emite disminuir cl deoprondi.iiento de polve durent* 5 - 10 cHeo (potando 1.5 - 2 d«" d* arterial por l a de la superficie. r El copleo de petróleo o aaatt, gastando 0.8 - X. por 1 • de eael- no y recubriéndolo luego coa gravili*, cesa la foraacloa de polvo por ua intervalo de 20 - JO tiles. Con e l nao de emisiones, coa gastos comprendidos entre 3 • 5 da' por 1 a de oaaiao. so rednee el contenido de polvo ea el aire basta lea concentraciones teenologlcaaeate peralaLblea por 60 90 dlaa, l o q*e depende de la intensidad dal trftfloo de caadoaes volquetes y do las condiciones aeterealogleaa. Para prevea» la contaalaaclon de la cantera eoa e l ¡»Ivo que proviene de eseorlalea y bordes, lea euperfldea correspondiente* se fijan por aedlo de agontea antloroalvoa» La* partea horlaontalea dal eaeorial a* fijan Bedlant* lapregneeloa eoa soluclaa da pollecrlloaltrllo al 0.5 %, loa gaotoa de liquido son de 10 da* par 1 a . la« partas verücalea y bordo* de cantera ola bcae flelar ae iapregnaa coa enulaloa tattaalBoaa al 15 % ( betfia HB-SH - 50*, silicato de sodio * », kldrdxldo da sodio - o.15«, ngaa - «»7.85 * ) . Loa gaetoe de aateriel ooa da 10 da" por cada a y el trataaiento ae repita aaa vaa ea doa o tree aftoa* Para eupriair e l polvo eaependido ea el aira y pera la aeración de dlfcrentaa partea de la eantera ae nan diseñado y ae oxplotaa eoa éxito lnotalacloaea de aeración y huaoeaacioa alaulteneaa(de tipo OV 7. La l a oalACloa ceta acatada sobre el chasis de un cánida y puode producir ua chorro serohldrlulioo cuyo e n u Joe son de PJtO a'/eeg de air* y ? a'/aora de a g i s . Para le aeración conerai do canteras so ha dinanado una serie de inetnleclonoa ventilodorna que coplean notoros de turbina y de propulr.i&h a chorro, con une potencia do 15.000 cnb'Uoe do fucrea. Sus flujos de aire cn la oocciSa prS::ima ri chorro al cansa 1.300 a /oep 7 1" velocidad sedia 892 en do unoo f r . 5 a/noc. T,o lntro-1'jcclön del conjunto do nertlo/j cJeocrttoo, p.irn la rllnln* clîln do '>ol»o on loo contorno rdderÄrRicna y t»rtn\1\rrïcpB, hn -vraltldo roducir oun conecntrnclonee hont« loe lini toa :x>mlrdblco por IB higiene ~8bllCB. 893 I »! D ! C r S r <? S ! P N /Î fl. Pulmer. Developments In dust control end dust 9uppression In mininq, tunnelling and quarrying, engineering control, organisational asoects, medical prevention. 1 L . L R bouffant., J.C. martin., H.Oanlel rFfet dus aero9ol9 da S B I S D'alumlniun oour la prevention traitement de la Silicose. Ctude expérimentale. et le 1 ffl.L.fl. Flindt. Prévention of illnes9 dua to allergenic [l du9t9 <ll.T.Ulmer. Coal iuorkers'Pneumoconio9Í9 lonq-tima treatment and ita outcome D.Clse., Namcy W . C a r o . Problems associated »ith the U9e of helf-ma9k respirators dusty environments of developing 895 countrie9 in Developments In dust control and dust suppression In mi.ni.ng, tunnelling and quarrying, engineering control, organisational aspects, medical prevention A. Bulmer, Safety and Engineering Department, National Union of Mineworkers, Great Britain. 1. Introduction Research over many years in the coal mining industry shows that the mass concentration of "respirable dust" measured by selective sampling in accordance with the Medical Research Council/ Johannesburg selection curve provides a good correlation with the incidence of pneumoconiosis* The product of average respirable dust concentration and duration of exposure can, therefore, be used to measure the hazard. There is no evidence to show that high respirable dust concentrations for short periods increase that risk, but exposure to high concentrations over several years does increase the risk of the incidence of pneumoconiosis as a result of fine dust being deposited and remaining in the lung. The effects of exposure to dusts encountered In other mines, tunnelling, quarrying and some Industrial undertakings create very similar problems, and the steps to be taken to counter the hazard are also similar. The report does not, however, attempt to deal with fibrous dusts, such as asbestos, or indeed toxic dusts. Because of the hazard created by airborne dust, the workforce must be made aware of the possible consequence of failure to properly control the working environment. The following points must receive constant attention. 1. Production and dispersal of respirable dust must be kept to a minimum. 897 2. Steps must always be taken to capture that dust which is dispersed* 3. There must always be provisions to protect the workforce from any harmful dust which remains when the foregoing requirements have been complied with. Requirements 1 & 2 can only be achieved if an effective re- liable means of measuring is systematically carried out. 2. Engineering Control (a) Minimising production and dispersal of respirable dust Producing mineral by mechanical means or explosives, crush- ing and transporting the said minerals creates dust particles of all sizes from the very smallest respirable sizes to the large sizes which cause other problems. One of the earliest methods of reducing respirable dust at source is wetting by infusing water into the mineral in situ prior to getting. This method is very effective when the right conditions exist, but many coal seams cannot be effectively infused, e.g. in the United Kingdom where coal seams are generally too homogeneous to be injected uniforally. When dust problems arise from floor or roof of a coal seam, or mid seam dirt bands exist, infusion has little effect on airborne dust production. Machines for the mechanised production of mineral or for driving underground roadways normally achieve this by rotating cutting tools or cutting tools mounted on cutting chains. Cutting tools must always be maintained in good condition because blunt tools increase the force required to cut, reduce the depth of cut 898 and produce much more fine dust. The number of cutting tools should also be kept to a minimum necessary to produce a given volume of mineral. Excessive numbers of tools means excessive work is being done on the mineral and excessive fine dust is produced. Similarly tool speeds should be kept to the minimum which will effectively break down the mineral. A minimum number of well maintained cutting tools rotating at low speed increase depth of cut and considerably reduce the make of fine dust. Further gains can be achieved by the use of water. Water sprays have been used for many years on machinery producing mineral but experience has shown that external . sprays contribute little to the reduction of fine dust. Water is much more effective if introduced ahead of the cutting tools« and this method is now common practice in the United Kingdom. Success in the use of wetting agents in the suppression of dust has been reported in Germany and Poland, but experiments and trials in the United Kingdom have been disappointing, showing no advantage to date. Experiments with the use of foam in both the United States of America and the United Kingdom have shown it is only effective for suppressing dust when excessively large quantities are applied to cutting tool machines. Machines operating on longwall coal faces can also derive benefits from the use of cowls to partly screen the dust source from the ventilating current. Passing water and air through drill roads Is very effective during drilling operations. 899 Respiratile dust produced and dispersed from shotflrlng operations can be kept to a minimum only by ensuring that the holes are correctly placed and charged in relation to the pull or burden. Such operations can also often take place when workmen have been withdrawn, remaining in a clean environment until fumes and dust have cleared« Crushing operations or industrial processes again produce respirable dust, but dispersal can be prevented or minimised by complete enclosure and the application of finely atomised water droplets within the enclosure. Transfer of minerals from one transport system to another can cause degradation, producing fine dust and/or dispersing such dust previously settled out. Enclosures and properly engineered and constructed equipment, chutes, wetting of conveyor belts etc., can keep this source to a minimum. Air velocities of more than four metres per second can raise dust previously settled out and should be avoided wherever possible. b. Capture of airborne respirable dust Many types of filter units or dust collectors are currently available falling into two basic categories, i.e. dry filters and wet-type dust collectors. Dry filters are generally more efficient that the wet type, but are not suitable, with certain exceptions, for use in the mining situation because of their size, dust dispersal, etc. Consequently, the dry type of filter is normally used in conjunction with enclosed extractor installations. 9oo Wet-type dust collectors are used more effectively In the mining heading or cul-de-sac situation. Free standing filter units situated In. .mine roadways and passing a large proportion of the total quantity of air In the ventilating current can substantially reduce the total dust content, Including respiratale sizes. When mine roadways or tunnels are being formed by mechanised means» overlap ventilating systems which Incorporate dust collection can be Integrated Into the total system successfully. Such systems can operate with main forcing ventilation provisions. Research and development has also taken place In the Un