Asbestos disease in maintenance workers of the chemical industry

Our plain-English summary of Asbestos disease in maintenance workers of the chemical industry, by R. Lilis, S. Daum, H. Anderson, et al (Annals of the New York Academy of Sciences, 1979).

The study

• Authors: R. Lilis, S. Daum, H. Anderson, M. Sirota, G. Andrews, I.J. Selikoff
• Journal: Annals of the New York Academy of Sciences
• Published: 1979;330:127-35
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M nos. 000830, 001036).

Abstract

In several large groups of workers employed in chemical plants, chest x-ray abnormalities (small irregular opacities and/or pleural changes) of the type known to be induced by asbestos were found in a proportion of those examined. A cross-sectional study of maintenance workers in a large chemical plant was undertaken to evaluate the prevalence of asbestosis; 185 workers were examined. Radiologic evidence of parenchymal interstitial fibrosis was found in 24% of those examined; in 10% of workers, parenchymal fibrosis was the only abnormality. Pleural fibrosis and/or calcification was found in the absence of parenchymal fibrosis in 14% of cases; in another 14% of workers, both parenchymal and pleural abnormalities were detected. The prevalence was significantly higher in those employed 20 or more years. Pleural abnormalities were more prevalent than were parenchymal changes. The increased risk of lung cancer and mesothelioma remains to be studied.

In plain English

This cross-sectional study examined 185 maintenance workers, such as welders, electricians and pipefitters, at a large New Jersey chemical plant. They were volunteers, about half of the plant's maintenance men. Four physicians read chest x-rays without knowing the workers' histories. Small irregular opacities of the type seen with lung (parenchymal) fibrosis appeared in 24% of the men, and were the only abnormality in 10%. Pleural thickening or calcification without parenchymal changes appeared in 14%, and both kinds of change in another 14%. Overall, 38% had changes consistent with asbestos-induced disease. Changes were more common in men first exposed more than 20 years earlier. Among the 140 men with no known asbestos exposure before this job, prevalences were almost identical. Of 108 men who never handled asbestos directly but worked where others did, 33 (30%) had abnormal x-rays. The authors concluded that maintenance work in chemical plants, including this bystander exposure, carries risks comparable, though not identical, to other asbestos exposures. They added that the risk of lung cancer and mesothelioma remains to be studied.

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 study (clinical field examination, including chest x-rays read blind and classified by the ILO U/C system, questionnaires, physical examination and lung function tests)
• Who was studied: 185 male maintenance workers (welders, carpenters, electricians, pipefitters and others) at a large chemical plant in New Jersey. They were volunteers, about half of the men in maintenance jobs. The authors deliberately sought men employed more than 10 years and examined only a sample of those employed for shorter periods.
• Exposure: Asbestos exposure during chemical plant maintenance work, with no fiber type named. Some men had direct, continuous exposure for longer than 5 years. Others had direct but intermittent exposure for shorter periods. More than half never worked directly with asbestos but were present where others did (bystander exposure). 45 men had some asbestos exposure before joining the plant.
• Main results:
  • Among all 185 workers, small irregular opacities (parenchymal fibrosis) were found in 24%. In 10% they were the only abnormality.
  • Among all 185 workers, 14% had pleural abnormalities only (pleural thickening 10%, calcification 4%), and another 14% had both parenchymal and pleural changes.
  • The overall prevalence of parenchymal and/or pleural abnormalities consistent with asbestos-induced changes was 38% of the 185 workers.
  • Abnormalities were more common in workers whose exposure began more than 20 years earlier. In Table 4, 66 of 77 (86%) with less than 20 years had normal x-rays, compared with 49 of 108 (45%) with more than 20 years. Pleural changes were more frequent than parenchymal changes.
  • In the 140 workers with no known asbestos exposure before working at the plant, prevalences of parenchymal and pleural abnormalities were almost identical to those of the whole group: parenchymal changes 24%, pleural changes 27%.
  • Abnormal chest x-rays by type of exposure: 20 of 41 (49%) with direct exposure for longer than 5 years; 17 of 36 (47%) with shorter, intermittent direct exposure; 33 of 108 (30%) with no direct (bystander) exposure.
  • Shortness of breath on exertion was the only symptom more frequent in workers with x-ray abnormalities. It was reported by 42% of those with both parenchymal and pleural changes, compared with 17% of those with normal x-rays.
  • Restrictive lung function was found in 5% of workers. A lower than normal FEV1/FVC ratio (an obstructive pattern) was found in 17% of workers who had never smoked. The authors suggested that dust, irritant fumes and gases may affect breathing function.
  • Chronic bronchitis was found in 20% of workers. The difference between current smokers (22%) and never-smokers (14%) was not statistically significant.
• The authors' conclusion: The authors concluded that the findings strongly suggest that asbestos exposure typical of chemical plant maintenance work, including indirect (bystander) exposure, carries risks comparable, though not identical, to asbestos exposure in other industries. They judged that the risk of disabling asbestosis is less with this type of exposure. They stated that the risk of lung cancer and mesothelioma is of concern and remains to be studied.

Topics

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

Medical terms in this study, explained in our Lexicon: Chest X-Ray, Interstitial Fibrosis, Fibrosis, Lung Cancer, Mesothelioma.

Related studies

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• Dangerous and cancer-causing properties of products and chemicals in the oil refining and petrochemical industry: Part V--Asbestos-caused cancers and exposure of workers in the oil refining industry — M.A. Mehlman (1991)
• War on Carcinogens: industry disputes human relevance of chemicals causing cancer in laboratory animals based on unproven hypotheses, using kidney tumors as an example — R.L. Melnick, J.M. Ward, et al. (2013)
• Ban on asbestos diaphragms in the chlorine-related chemical industry and efforts toward a worldwide ban — F. Giannasi (2007)
• Cause-specific mortality among male chemical workers — G.G. Bond, E.A. McLaren, et al. (1987)
• Incidence of cancer and mortality among workers exposed to mercury vapour in the Norwegian chloralkali industry — D.G. Ellingsen, A. Andersen, et al. (1993)

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