Asbestosis in an asbestos composite mill at Mumbai: a prevalence study

Our plain-English summary of Asbestosis in an asbestos composite mill at Mumbai: a prevalence study, by V. Murlidhar, V. Kanhere (Environmental Health, 2005).

The study

• Authors: V. Murlidhar, V. Kanhere
• Journal: Environmental Health
• Published: 2005;4:24
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Of an estimated 100,000 workers exposed to asbestos in India, less than 30 have been compensated. The reasons for such a small number are: refusal by management sponsored studies to grant medical certifications to workers suffering from occupational diseases, lack of training for doctors in diagnosis of occupational lung diseases, deliberate misdiagnosis by doctors of asbestosis as either chronic bronchitis or tuberculosis and the inherent class bias of middle class doctors against workers. The aim of the study was to identify workers suffering from Asbestosis (parenchymal and pleural non-malignant disease) among the permanent workers of the Hindustan Composites Factory and assess their disability and medically certify them, whereupon they could avail of their basic rights to obtain compensation and proper treatment.

Methods: The study was conducted by the Occupational Health and Safety Centre and the Workers' Union. Asbestosis was diagnosed if they had an occupational history of asbestos exposure for at least 15 years and showed typical radiographic findings.

Results: Of 232 workers in the factory, 181 participated in the survey. 22% of them had asbestosis. All the asbestos affected workers had at least 20 years of exposure. 7% had rhonchi, 34% had late basal inspiratory rates, 82% had more than 80% of Forced Expiratory Volume in the first second (FEV1)/Forced Vital capacity (FVC) ratio and 66% had FVC less than 80% of the predicted value. On radiology 7% had only pleural disease, 10% had both pleural and parenchymal disease and 82% had only parenchymal disease. The association of pleural disease with chest pain was statistically significant.

Conclusion: We found the prevalence of asbestosis among exposed workers to be less than that anticipated for the number of years of exposure due to "Healthy Worker Effect". We suggest that all affected asbestos workers (including those who have been forced to leave) in India be medically certified and compensated. We also recommend better control of asbestos use in India. We also implore the management to provide all information about the work process and its hazards, conduct medical checkups as mandated by law and give the medical records to the workers.

In plain English

This was a prevalence survey of asbestosis, meaning non-malignant disease of the lung tissue or pleura, at the Hindustan Composites asbestos factory in Ghatkopar, Mumbai, India. The factory has asbestos textile, compressed asbestos fiber, and brake and clutch lining departments, and uses what the article calls white asbestos. In November 2004, outside the factory gates, 181 of the 232 permanent workers answered a questionnaire and had examinations, breathing tests and chest X-rays. Management did not cooperate, and contract workers did not attend. Asbestosis was diagnosed from at least 15 years of exposure plus typical X-ray findings. Of the 181 workers, 41 (23%) had asbestosis. Among those 41, 66% had forced vital capacity below 80% of predicted, and average disability was 32%. Two had lung or pleural tumors, and lung cancer was confirmed in one. Five of the 7 cases with pleural disease reported chest pain, compared with 1 case with parenchymal disease, which the authors reported as statistically significant (p = 0.05). The authors concluded that prevalence was lower than expected, mainly because of the "healthy worker effect".

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: cross-sectional prevalence survey (questionnaire, physical examination, lung function tests and chest X-rays) held over four days at the factory gates
• Who was studied: 181 of the 232 permanent workers of the Hindustan Composites asbestos factory, Mumbai, India, examined in November 2004. About 100 contract (temporary) workers did not attend.
• Exposure: Work with 'white asbestos' in the asbestos textile, compressed asbestos fiber and brake and clutch lining departments (the 'dusty sections'), and in maintenance and other departments. Information on the work process came from the workers themselves.
• Main results:
  • 41 of the 181 workers examined (23%) had asbestosis
  • 34 (82%) of the 41 cases came from the dusty sections and 7 (18%) from other departments. The authors state this difference was not statistically significant.
  • The article reports that all workers had at least 20 years of exposure and 51% had more than 30 years
  • Among the 41 workers with asbestosis: 66% had FVC below 80% of predicted, 37% had FEV1 below 80% of predicted, and 82% had an FEV1/FVC ratio above 80%
  • Among all 181 workers tested: 62% had FVC below 80% of predicted and 15% had FEV1 below 80% of predicted
  • On chest X-ray, among the 41 workers with asbestosis: parenchymal disease in 92% (82% parenchymal only), pleural disease only in 7%. Pleural disease overall was found in 17%.
  • 5 of the 7 cases with pleural disease reported chest pain, compared with 1 case with parenchymal disease. The authors reported this as statistically significant (p = 0.05).
  • Among the workers with asbestosis: none had clubbing, 7% had occasional rhonchi, and 34% had late inspiratory basal crackles
  • Two workers with asbestosis also had pleural or lung tumors. In one, lung cancer was confirmed by HRCT and lung biopsy; the other declined further investigation.
  • The average disability of the workers with asbestosis was 32%
• The authors' conclusion: The authors concluded that asbestosis prevalence was lower than expected for the years of exposure, mainly because of the 'healthy worker effect'. They recommended better control of asbestos use in India.
• Limitations the authors state:
  • Affected workers who had been forced to leave, took voluntary retirement, or died were not included (healthy worker effect)
  • Contract (casual) workers, in whom the authors think prevalence would probably be higher, did not take part
  • Only one worker had HRCT, because of financial constraints. The authors note HRCT might have found more cases.
  • The authors could not trace workers who had left or retired
  • Management refused access, so the description of the work process relies on workers' knowledge

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Occupational Disease, Occupational Lung Disease, Misdiagnosis, Occupational History, Asbestos Exposure, FEV1, Healthy Worker Effect.

Related studies

• Prevalence and features of advanced asbestosis (ILO profusion scores above 2/2). International Labour Office — K.H. Kilburn (2000)
• Asbestosis: Past voices from the Mumbai factory floor — A.V. Jadhav, N. Roy (2012)
• Compensation, radiographic changes, and survival in applicants for asbestosis compensation — W.O. Cookson, A.W. Musk, et al. (1985)
• Prevalence of radiographic asbestosis in crocidolite miners and millers at Wittenoom, Western Australia — W.O. Cookson, N.H. De Klerk, et al. (1986)
• Ventilatory function after exposure to various respirable hazards in a population of former coal miners — G.M. Calvert, M. Moore, et al. (1991)
• Mortality in the chrysotile asbestos mines and mills of Quebec — J.C. McDonald, A.D. McDonald, et al. (1971)

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