Document 8RpQzJxQ4DNLQ8mwxZ1yJn7KK

FILE NAME: Asbestos in India (IND) DATE: 1996 DOC#: IND024 DOCUMENT DESCRIPTION: Journal Article - The Correlation of Chest Radiograph and Pulmonary Function Tests in Asbestos Miners & Millers -1 Jt i'l .1 I.r a Lahoralory haler Hence ipV 'on write to. ay 400 008 The Correlation of Chest Radiograph and Pulmonary Function Tests in Asbestos Miners and Millers S.K. Dave, L J . Bhagia, P.K. Mazumdar, G.C. Patel, P.K. Kulkarni and S.K. Kashyap National Institute of Occupational Health, Me, hani Nagar, Ahmedabad An environmental-cum-medical survey was carried out in asbestos mines and milling units at Pullivendalla, Cuddaph (A.P.) India. This was done in two mines and six milling units with,95% qf the total work force being surveyed. Out of a total ol 633 registered workers, 329 (52%, all males) were employed in mines while 135 (21.4%) workers of whoml 14 (84%, all females) were employed in the milling u.niis All subjects unciowent limited medical examination, spirometry and chest radiographs. The levels oi asbestos fiber concentration was much below threshold limit value (TLV) in underground mines but several times higher than TLV in milling units. The percentage of workers with abnormal pulmonary function tests (PIT) and chest radiographs increased with duration o f exposurein smokers as well as non-smokers. Restrictive pattern of lung functions (159 workers-16.27%) was more common than obstructive (33 workers-5.21 %) and combined type (22 workeis-3.4%). Si milarly, the parenchymal changes (156 workers-24.6%) were more common than pleural (27 workers-4.3%). As most of the males were employed in mines, where the fiber levels were much below TLV, the number of male workers with normal PFT and chest radiographs were ten times (61.3%; more than male workers with bolh die parameters abnormal (6.3%). As most of the females (114 our of 120 95%) were employed in milling units, where the levels of fibers were several times higher than TLV, the number of females having both the parameters normal 29 i <4 i%) ()r abnormal 35 (29.2%) were similar. Key words : Asbestos mines, asbestos nulls, chest radiograph, pitbnon u v fum non tests. [Indian J Chest Dis Allied .Sc. 1996; JH : Hl-M] The results o f extensive epidem iological and toxicological studies have confirmed that respiratory m orbidity due to'asb estos exp osu re is related to the d ose and durauon ot exposure, the processes o f work and type o f fiber1'3. . ' W hile studying respiratory morbidity due to asbestos exposure attempts were being made to find out the relationship o f ch est radiographs and pulm onary function tests in work environment. Attempts were also made to observe the interdependency of these two objective parameters with each other. W hile such efforts do not throw direct light on, tor Correspondence : Dr S.K. Dave, Deputy Director and Head, Occupational Medicine and Epidemiology Division, National Institute of Occupational Health Meghani Nagar, Ahmedabad-380 016. S. K. Dave et al instance, the prevalence of health effects of hazards, they have lead to some interesting speculation regarding the sensitivity of such tests in detecting the early charges in health status4. . In India, more than 30 mines are located in Andhra Pradesh and Rajasthan. The serpentine (Chrysotile-17,000 metric ton) variety is available in Andhra Pradesh and amphibole (Tremolite-25,000 metric ton) in Rajasthan. The latter variety is .technically of very poor grade. As per the directives of the Indian Council of Medical Research (ICMR), New Delhi, the National Institute of Occupational Health (NIOH), Ahmedabad initiated "Intervention study in asbestos mines and milling units in India" at the national level. The findings presented here are the part bf overall observations made from the entire study whose objectives were (i) to measure the asbestos fiber levels in mines and milling units, (i'i) to assess the health status of workers in asbestos mining and milling units, (Hi) to correlate the effects of work environment on respiratory system in reference to two objective parameters, i.e. chest radiograph and pulmonary function tests and (iv) to find out the interdependency of two objective parameters, i.e. chest radiography and pulmonary function tests on each other. . Material and Methods Environmental Evaluation. The environment was evaluated in two mines and six milling units at Pullivendalla, Cuddaph in Andhra Pradesh, India. (a) Collection of samples. As recommended by the Bureau of Indian Standards (BIS)5, the millipore membrane filter method (MMFM) was used. The minimum number of samples taken were four. A total of 157 samples were collected from the breathing zone of workers by personal samplers at various locations. The dust was collected on cellulose membrane filter with 25 mm diameter and 0.8 pm pore size at the flow rate of 1.5 L/min. (b) Counting. A phase contrast microscope (x 400) with Walton-Becklet graticule specially designed for asbestos fiber counting was used. One hundred fibers or 100 fields were counted with minimum count of 20 fields. All fibers with length > 5 pm and diameter (width) < 3 pm and length to diameter ratio 3 : 1 or more were counted. Fiber concentration was calculated by using the following equation: (.A/a) x (1/r) x (M) where A is for effective area, i.e. 325.88 mm2, a for graticule area, i.e. 0.006936 mm2, r for ilow rate, i.e. 1.5/min, t for sample duration (min), N = total number of fibers counted, and n for number of graticule area counted (< 100). Health Status Study. This study comprised of 633 (513 males and 120 females) workers (95% of the work force) of the asbestos mines and milling units at Pullivendalla, Cuddaph, A.P., (India). - (a) Questionnaire A included a medical scctic bias non-smokers wcie ( were considered as smoke {b) Limited physical e presence of infra-axillan period of breath holding i (c) Spirometry. Spin performed a minimum of reading of the forced ex| (FVC) were used for an Kamat et aP. {d) Chest roentgenog roentgenogram as per the three chest physicians ani Results In mines, the levels ol for chrysotile fiber \i e , < Rule 123-A undei Sectioi applicable to chrysotile n Table 1. Semi-Mechanic. to some interesting ly changes in health ind Rajasthan. The ndhra Pradesh and ety is.technically of 1Research (ICMR), hmedabad initiated national level. The >m the entire study id milling units, (if) its, (Hi) to correlate e to two objective [iv) to find out the pulmonary function ies and six milling i Standards (BIS)5, limum number of breathing zone of cted on cellulose ite of 1.5 L/min. Becklet graticule ibers or 100 fields (tm and diameter iber concentration 106936 mm7, r for bers counted, and females) workers endalla, Cuddaph, Correlation o f chest radiographs and PFT in asbestos workers S3 (a) Q u estio n n a ire. A standard questionnaire administered by trained interviewers included a medical section, a section on occupational history and smoking habit'1. To avoid bias non-smokers were defined as those who had no exposure to tobacco and remaining were considered as smokers. (b) L im ited p h ysica l exam ination. Auscultation Was performed on site to determine the presence of infra-axillary crepitations heard at the full inspiration especially after a short period of breath holding at the low lung volumes. , , (c) S p iro m etry. Spirometry was performed by Vitalograph (7.1 L). Each subject performed a minimumi of three technically satisfactory forced expiratory manoeuvers. The reading of the forced expiratory volume in one second (FEV,) and forced vital capacity (FVC) were used for analysis. Predicted normal values were obtained from the data of Kamat e t aP. ' ` (d) C h e st ro entgenogram s. All workers-underwent a full size postero-anterior chest roentgenogram as per the recommendations made by ILO (1980). The films were read by three chest physicians and common agreement was taken for analysis8''. Results In mines, the levels of asbestos fibers were much below the threshold limit value (Tl.V) fo( (ffiyysqqEi IBl!^|Tg.TSTl7mTr^Htc<i^accepted by the Government of India in Model Rule 123-A under SectionTiTof the Factories Act 1948 as ammended in 1987 which is also applicable to chrysotile mine and m illing environment10. , Table 1, Mean asbestos fiber concentration in two types o f mill', Semi-Mechanic Semi-AutomaiiiC Operation (f/ml) Operation (f/ml) Jaw crusher Decoiticntor Loader Fiber room Vibrator Hand screening 244.14 " (6.69-40.79) 52.27 (12.49-141.9) 45.92 (30.0-63.9) 148.96 (9 i.05-220.79) 224.33 (96.77-488.05) 101.30 (51.54-214.71) Fiberision Primary screening Fiber collection Tailing plant ` (Feeding) Tailing plant (collection) -- 21 43 (3.32-41.92) 33.27 (8.4-60.97) 75.28 (19.07-54.77) 144.42 (2 05-26.76) 3.98 (1.3(1-6.60) Figures in parenthesis indicate K4 S.K. Dave et al The mean asbestos fiber concentration in two types of mills have been shown in table-1 Mean asbestos fiber concentration at various locations of the semi-mechanic mill was higher as compared to the location of the semi-automatic mills. However in both the type of mills, the fiber levels^were several times higher tha i TLV (< 2 f/ml) Tail location's:fl"rAean fiber level was highest near the vibrator ( m 2 3 f/ml) in semi-mechanized mill, ^ s e m i automatic mill, the hi^snSveTwasTobservedlneaftfemlingplant (Feeding-144.42 f/ml). The distribution of workers according to the nature and duration of exposure and smoking habit in both the sexes is shown in table-2. The directly exposed group included workers working either in mining and/or milling, while those working as supervisor, mechanic, electricians, helpers, drivers etc have been included in indirect exposure group! Out of a total of 633 workers, 341 (53.8%) had less than 10 years exposure, 186 (29 3%) with 11 to-15 years and 106 (16.7%) with more than 15 years. Out of th total work force, 329 workers (52%, all males) were employed in mining, 199 (31.4%) in milling, 23 (3.6%) in mining and milling and 82 (12.9%) in indirect exposure processes. Out of a total of 513 male workers, 282 (54.9%) were smokers while 22 (18.3%) of the 120 females smoked. Table 2. Distribution o f workers ccording to nature and duration o f exposure and smoking habits in both sexes . Duration of exposure Sex (yrs) Direct exposure group Mining Milling NS NS Indirect exposure group Mining + Milling NS NS Total < 1() M 341 (53.8'/( ) F 11-15 M 186 1,29.4%) F > 16 M 106 (16.51%) F 115 95 (22.41) (18,51) - 34 (6.62) 40 (7.79) - 15 (2.92) - 30 (5.84) - 20 (3.89) 32 (26.6) 7 (1.36) 41 (34.16) 3 (0.58) 19 (15.83) 26 (5.06) 8 (6.06) 17 (3.31) 8 (6.66) 12 (2.33) 6 (5,00) 4 (0.78) _ 3 (0.58) - 2 (0.38) _ 5 (0.97) -- 6 0.16) - 3 (0.58) _ 17 (3.31) 2 (1.6) 7 (1.36) 3 (2.5) 4 (0.77) 1 (0 83) Total 164 165 122 77 (25.9) (26.06) (19.27) (12.16) 9 (1.42) 14 (2.21) 34 (5.37) NS ^ Non smoker. S -- Smoker: Figures in parenthesis indicate percentages Male smokers = 282 (54.9%), Female smokers = 22 (18.3%) 17 (3.31) _ ,20 (3.89) _ 11 (2.14) 299 (47.1) 42 (6.6) 134 (21.2) 52 (8.1) 80 (12.6) 26 (4.1) j , p ;? " > ! * 48 633- I (7.58) n Table 3. Pub Operation group Si Direct exposure \ Mining I Milling |N t Mining and milling 5 Indirect exposure i\ 1 Total Figures in parenthesis irid Impairment of lung iui of both the sexes is show common (103 workers-16. mixed pattern was observ 18.5%), the p revalence o workers-36.2%) and in wo workers of the indirect e impairment w as nearly counterparts. The radiological chan workers-54.8%) than min changes in direct as well common (166 workers-26. was detected in 6 workers In milling units and n changes were more comm T T ;a1 w ap11! T* m w Correlation of chest radiographs and PFT in asbestos workers 8S Table 3. Pulmonary function impairment in different operation groups Operation group Direct exposure Mining -r i Milling Mining and milling Indirect exposure ` Sex M F M F M M F Pulmonary function impairment No. of workers Restrictive Obstructive Combined Total 329 . 26 25' (7.9). (7.6) - - - 85 14 2 (16.5) (2.3) 114 48 2 (42.1) (1.8) 23 1 1 (4.3) (4.3) 76 12 3 (15.8) (3.9) 6 2 -- (33.3) 10 (3) -2 (2.3) 4 (3.5) 6 (7.9) 61 (18.5) 18 (21.2) 54 (47.3) 2 (8.7) 21 (26.7) 2 (33.3) Total 633 , 103 33 (16.27) (5.2) 22 158 (3.4) (25) Figures in parenthesis indicate percentages Impairment of lung functions in workers in both directly and indirectly exposed groups of both the sexes is shown in table 3. It was observed fta^restric^j^attern^was^m ore Mimmon(103iyjiy|ceys.-.I6.27%) as whye a mixed pattern was observed in. 22,workers &A%), As c o mpared to miners (61 workers- 18*5%), the prevalence of lung function impairment was more common in millers (72 workers-36.2%)Tahd in'workersln the indirect exposure group (23 workers-28%). In fgoale workers of the indirect of res.tiictlvs. impairhfffHr^aiTTiiiafly two to twp-and-half times more common than their male counterparts.' The radiological changes were more common in workers in the milling units (109 workrs-^k8%) Thaa tnining u)iit (64 workers-19.5%) (Table 4). AmaQgst radiqtogieal changes in direct as well as indirect exposure group, parenchymal changes were c<ftn^on-(i66!Worirere26.'2%Hhan`p te a fS T o h F t2 T w d ik m ^ 5 % )r R iT ^ n a i^ tuberculosis was detected in 6 workers (1% ),all.Qtthem were maiesmokers. In milling units and in the indirect exposure group the prevalence of parenchymal changes were more common in females (milling units-28 males,, i.e. 33% out of 85 and 62 86 S.K. Dave et al fem ales, i.e. 54.38% out of 114; indirect exposure group 13 males, i.e. 17.1% out of7j6and one female, i.e. 16.6% out of 6). Thus, the radiological changes also had a similar pattern as the pulmonary function tests. . Correlation of chest radiographs and pulmonary function tests in asbestos miners atid m illers of both the sexes is summarized in table 5. Out of the total of 513 male worker^. 317 (61.3% ) were having both the parameters normal w h ile 3 ltil3 %) ftad both,the parameters abnorm arO f the T20lemTe*woM en^ the parameters nonmarwhile 35 (29.2%) had both parameters abnormal. In case of male workers, 71 (13.8%) were with abnormal PFT and normal chest x-ray and 94 (18.4) had normal PFT and abnormal chest x- ray. In fem ale workers the corresponding figures Were 21 (17.5%) and 35 (29.2%), respectively. Here, it is worthwhile to note that males were employed mainly in mines (underground) due to prohibition of employment of females on such locations. Thus, the fem ales were largely employed in milling units (95% out of 120 females) and indirect Table 4. Radiological changes in different operation groups Operation group Sex No. of workers Radiological changes Parenchymal changes Pleural. changes Total Pulmonary tuberculosis IO RO CO PI' PCa Direct exposure Mining M 329 31 1 (9.4) (0.3) P Milling Mining and milling M 85 28 _ (32.9) I- 114 42 - (36.8) M 23 3 (13.1) F - - - Indirect exposure M 76 8 1 (10.5) (1.3) F 6 - - 18 6 3 (5.5) (1.8) (0.9) 7 (8.2) 20 (17.5) 2 (8.7) - 4 (4.2) 4 (3.5) 1 (4.37) - - 3 (2.6) - - 4 6 - (5.3) (7.9) 1 - ~ (16,6) 5 64 (1.5) (19.4) 1 (1.2) _ - 40 (47.1) 69 (60.5) 6. > (26.1) - , 19 ,(25) - '- Total . ' 633 112 2 52 (17.7) (0.3) . (8-2) 21 (3.3) 6 .6 (1.0) (1.0) 1.0. = Irregular opacities, R.O. w Regular opacities, C.O. = Combined opacities, P.T. = Pleural thickening, P. Ca. = Pleural calcification . Figures in parenthesis indicate percentages ('tn Table 5. Correlation oj ch millers Pulmonary function tests Normal Abnormal Figures in parenthesis im exposure process. A s a re. fem ales to much higher le in M odel Rule 123-a und which is also applicable conclusion, that when the the levels arc compaiative Discussion The fiber levels were ri the fiber in parent rock (; reduction of the fiber leve Du Toit11also observed thi mining as compared to um In the m illing units, i locations the fiber levels \ Government o f India in M ammended in 1987 and is be mainly due to three reas* and safety act and (<) low and m illing units, total pre nulling units. Such a low ; the reason for their resist, prevailing lack o f awarent absence o f low cost indigei P ] Contribute to an extrem e Countries lik e Canada (Qu profitable asbestos mines w - .-5 HHjlW |l|lll!l Correlation o f chest radiographs and PFT in asbestos workers K7 Table 5. Correlation o f chest radiographs and pulm onary function tests in asbestos miners and millers Pulmonary function tests Normal Chest radiographs Males (513) Normal Abnormal . 317 (61.7) 94 (18.4) Females (120) Normal Abnormal 29 (24.1) 35 (29.2) Abnqjmal 71 (13.8) 31 21 35 (6.3) (17.5) (29.2) Figures in parenthesis indicate percentages exposure process. As a result males were exposed to very low levels (i.e., < 0.5 f/ml) while females to much higher levels than the TLV (< 2 f/ml) accepted by the Government of India in Model Rule 123-a under Section 112 of the Factories Act 1948 as ammended in 1987, which is also applicable to chrysotile mine and milling environment. However, the conclusion, that when the fiber levels are too high, chest radiographs are affected and when the levels are comparatively low, pulmonary function tests are affected can't be derived. Discussion ft` . , The fiber levels were much below TLV in mines due to wet drilling and low content of t i M t m i ^ g ' ^ ^ ' p i ^ ' l a significant role in the rediicfioh of the fiber levels to a significant extept. In the South African mines, Gibbs and also observed the levels of asbestos fiber were two to three times higher in surface mining as compared to underground one. In the milling units, in the general work environment, as well as at various other locations the fiber levels were much higher than TLV (< 2 f/ml) which is accepted by the Government of India in Model Rule 123-/. under Section 112 of the Factories Act 1948 as ammended in 1987 and is applicable to chrysotile mine and milling environment This can be mainly due to three reasons : (a) obsolete technology, (b) inadequate compliance to mines and safety act and (c) low content of asbestos fiber in parent rock. In Pullivendalla mines and milling units, total production of chrysotile is approximately 17,000 metric ton by six milling units. Such a low yield gives poor economic returns to mine/mill owners which is the reason for their resistance in investing in environmental engineering controls. The prevailing lack pf awareness about health risks due to asbestos in miner and millers and absence of low cost indigenous technology aggravate the problem further. All these factors contribute to an extremely dusty working condition in these asbestos milling units. Countries like Canada (Quebec)12, Cyprus'5, Italy14and South Africa" have economically profitable asbestos mines which contribute nearly 30% of the total world production. Studies 88 S.K. Dave et al carried out in these countries reported significantly high levels in general mill environment- However, records maintained since 1940 in South Africa, Canada and Italy documented significant decrease in the environmental concentration of asbestos fibers over the past 40 years 1, 12,14 W e observed that the percentage of male workers with both parameters normal (61.3%) was ten times more than the percentage of ~v^rKFs~wuth both the parameters abnormal cases of female workers there was not much difference in the percentage of workers having both the parameters normal (24%) and abnormal (29%). This could be due the lact that in underground mines only males are permitted legally to work and the fiber levels were much below TLV in these mines. This results in females being predominantly employed in milling units and other indirect processes where the fiber levels were several times higher than TLV. Thus, the highly significant difference in fiber levels between mining and milling units kept male work force healthier than their female counterpart. Similarly restrictive pattern of PFT and radiological parenchymal changes mainly in the form o f irregular linear opacities were more common in milling workers than in miners. ; A study carried out in British Coluipbia reported decreased levels of forced vital, capacity > in those working in the mill area knowh for its high levels of exposure to asbestos fjberft1^ | Similar magnitude of deficit of FVC (8.9%) has also been reported in a Quebec studyl6,W e ; noted parenchymal changes on radiology in 12.2% of the workers studied which was in , conformity with similar studies ip asbestos mines and milling units in Q uebec^,C yprus^ * Italy13and British.Columbia15where parenchymal changes observed were 8%, 29% and 11%, respectively. The figures for pleural changes varied from 2 to 7% in all these.studies except in an Italian study where it was.13%13. Studies of lung function and. radiography have been reported from Quebec4 and Italy13and in both the studies levels of lung function was noted to be related to the abnormalities observed radiologically. The analysis of these studies also revealed that inter-relationship of the two objective parameters, i.e. chest radiograph, spirometry and their dependence on environmental levels of asbestos fiber. It also depends to a major extent on pre-employment health status and individual host susceptibility41116. References 1. irwing RS, DuToit J, Sluis-Cremer GK, Solomon A, Thomas R. Risk of asbestosis in crocidolit e and amosite in South Africa. Ann N Y Acad Sci 1979; 330 : 35-52. 2. Rossister CE, Bristol LJ, Cartier PH, ct al. Radiographic changes in chrysotile asbestos mine , and mill workers of Quebec. Arch Environ Health 1972; 24 ; 388-400. 3. Felton, Jean Spencer. Radiographic search for asbestos related disease in a naval shipyard. Ann NY Acad Sci 1979; 330 : 341 -352. - 4. Becklake MR, Fourriier-Massey G, McDonald JC, Siemiatycki J, Rossister CE. Lung function in relation to radiographic changes in Quebec asbestos workers. Proceedings o f the Interna tional Confen nee on Pneumoconiosis, Johannesburg, SA. 1970; 233-239. ( Bureau o f Indian fiber concentratior American Lung A adults and childrci Kamat SR, Tyagi I : 11-21. International Lab Pneumoconiosis ( 1 fice, Geneva, Swit Rossister CE, Har Proceedings o f the Exposure limits in Labour Office, 198 Gibbs GW, DuToi Scientific Publicati McDonald JC, Be chrysotile asbestos McDonald JC. Asb Scientific Publicati. Vigalani EC. Asbe Conference on Pne. Enarson DA, Embi miners in British G Becklake MR, Fou. asbestos mine and r 11 ' "V! m !' M - i ' ' " ' rjL s.; Correlation o f chest radiographs and PFT in asbestos workers 89 Bureau o f Indian Standards IS 11450-1986. Method of determination of airborne asbestos fiber concentration in work environment by light microscopy. American Lung Association. Recommended respiratory disease questionnaire for use with adults and children in epidemiological! reasearch. S' V Kaniat SR, Tyagi NK, Rashid SSA. Lung function in Indian adult subjects. Lung India 1982; I ; 11-21. International Labour Office : ILO/UC International Classification of Radiographs for Pneumoconiosis (1979). Occupational Safety and Health Series XX; International Labour Of fice, Geneva, Switzerland. Rossister CE, Harris PG. Choice of radiography for assessing effects of asbestos exposure. Proceedings o f the International Conference on Occupational Health (Abstract); 1975 ; p. 128. Exposure limits in various countries (Appendix-A) ; Safety in use of asbestos. International Labour Office; 1984 ; 94-96. Gibbs GW, DuToit RSJ. Environmental data in mining : Biologic eflccts of asbestos. IARC Scientific Publication No. 8 lARC-Lyon. France; 1973 : 138-144. McDonald JC, Becklakc MR, Gibbs GW, McDonald AD Rossister CE. The health 1 chrysotile asbestos mine and mill workers of Quebec. Arch Environ Health 1974,2 8 . 6 1 -68. McDonald JC. Asbestosis in chrysotile mines and mills: Biological effects of asbestos. IARC . Scientific Publication No. 8. ARC-Lyon, France; 1973 : 189-194. . Vigalani EC. Asbestos exposure and its results in Italy. Proceedings o f the 2nd International ; Conference on Pneumoconosis, Johannesburg, SA. 1970; 192-196. . Enarson DA, Embree V, Maclean L, Grzybowski Respirator^ health in chrysotile asbestos miners in British Columbia: A longitudinal study. Br J Med 1988; 45 :459-463.i. i. Becklakc MR. P.urnicMaaaey O. Ria.Wer asbestos mine and mill workers of Quebec. Arch Environ Health 1972, 24.40,1-408.