Asbestosis: interstitial pulmonary fibrosis and pleural fibrosis in a cohort of asbestos insulation workers: influence of cigarette smoking

Our plain-English summary of Asbestosis: interstitial pulmonary fibrosis and pleural fibrosis in a cohort of asbestos insulation workers: influence of cigarette smoking, by R. Lilis, I.J. Selikoff, Y. Lerman, et al (American Journal of Industrial Medicine, 1986).

The study

• Authors: R. Lilis, I.J. Selikoff, Y. Lerman, H. Seidman, S.K. Gelb
• Journal: American Journal of Industrial Medicine
• Published: 1986;10(5-6):459-70
• Cited by: 51 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 no. 000413).

Abstract

A cohort of 1,117 asbestos insulation workers was established in 1963 and has been prospectively followed since then. Chest X-ray abnormalities detected at the initial medical examination, and interpreted according to the International Labour Office Classification of Radiographs of Pneumoconioses are reported in this paper. The prevalence of all radiographic abnormalities (pleural and pulmonary) increased with duration from onset of asbestos exposure. A positive smoking history was associated with a significantly higher prevalence of small irregular opacities indicating interstitial pulmonary fibrosis. Such an association was not found for pleural fibrosis. The possible mechanisms which underlie the effect of smoking on asbestos-induced interstitial fibrosis seem to be of much less importance in the development of pleural fibrosis. Progression of radiographic changes over the 20-year interval 1963-1983 will be separately reported as will the predictive significance of these changes.

In plain English

This study examined chest X-rays taken in 1963 at the first medical examination of 1,117 New York-New Jersey asbestos insulation workers, who were 89.4% of the 1,249 eligible union members. The films were reread using the 1971 International Labour Office classification without knowledge of each man's age, time since first exposure or smoking habits. The article does not name the asbestos fiber types involved. No definite small irregular opacities, a sign of interstitial lung fibrosis, were seen in 695 men (62.2%). All pleural and lung abnormalities became more common with longer time since first exposure. Men who had ever smoked cigarettes showed these opacities more often than men who had never smoked cigarettes regularly: 17.8% versus 3.0% among those under 10 years from first exposure, and 36.6% versus 15.1% at 10 to 19 years. The difference shrank with time and was not statistically significant at 40 or more years. No statistically significant or consistent smoking effect was found for pleural fibrosis, diaphragmatic plaques or pleural calcification. The authors concluded that whatever drives smoking's effect on lung fibrosis seems much less important for pleural fibrosis.

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 analysis of chest X-rays from the initial (1963) examination of a prospectively followed cohort. The films were reclassified by the 1971 ILO system without knowledge of age, exposure duration or smoking.
• Who was studied: 1,117 men examined in 1963, out of 1,249 eligible. Eligible men were everyone who had been a member of the New York-New Jersey Metropolitan locals of the asbestos insulation workers' union between January 1, 1943 and December 31, 1962. There were 894 men with a positive cigarette smoking history (current and ex-smokers) and 223 who never smoked cigarettes regularly; some in the never-smoked group may have smoked a pipe or cigars.
• Exposure: Asbestos insulation work, measured as years from onset of asbestos exposure. No fiber type is specified. 31.6% of the men had less than 10 years from onset, 33.9% had 10 to 19 years and 34.5% had over 20 years.
• Main results:
  • Among all 1,117 workers, 695 (62.2%) had no definite small irregular opacities (interstitial pulmonary fibrosis). 385 (34.5%) were in profusion category 1, and 37 (3.3%) had higher profusion.
  • Under 10 years from onset of exposure, small parenchymal opacities were found in 17.8% of men with a history of cigarette smoking (51 of 286) versus 3.0% of men who never smoked cigarettes regularly (2 of 67). At 10 to 19 years, the figures were 36.6% of cigarette smokers (112 of 306) versus 15.1% of those who never smoked cigarettes regularly (11 of 73) (Table VI).
  • The difference in small opacities between cigarette smokers and never-smokers decreased as time from onset of exposure increased. It was not statistically significant in workers with 40 or more years from first exposure.
  • Pleural fibrosis became more common with longer time from onset of asbestos exposure.
  • Pleural fibrosis was slightly more common in smokers in most subgroups, but none of the differences were statistically significant.
  • Among all workers, diaphragmatic pleural plaques were seen in 342 (30.6%). Smoking status had no consistent influence on their prevalence.
  • Pleural calcifications were found in 170 workers (15.2%), 152 of whom had over 30 years from onset of exposure. No effect of smoking on calcification was found.
  • Across all 1,117 workers, pleural fibrosis (488, 43.7%) was slightly more common than parenchymal interstitial fibrosis (422, 37.8%).
  • Parenchymal (lung tissue) abnormalities were significantly more frequent in workers with a history of cigarette smoking than in those who never smoked. No such association was found for pleural changes.
• The authors' conclusion: The authors contrasted the effect of smoking on asbestos-related lung (parenchymal) fibrosis with the absence of a demonstrable significant effect on pleural fibrosis. They suggested that the mechanisms behind smoking's effect on interstitial fibrosis seem much less important for pleural fibrosis. They also suggested that with longer time from exposure, the effect of smoking is overshadowed by the effect of asbestos.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Interstitial, Pulmonary Fibrosis, Fibrosis, Insulator, Chest X-Ray, Asbestos Exposure, Interstitial Fibrosis.

Related studies

• Clinical findings among asbestos workers in U.S.: influence of cigarette smoking — Y. Lerman, I.J. Selikoff, et al. (1986)
• Interaction of asbestos, age, and cigarette smoking in producing radiographic evidence of diffuse pulmonary fibrosis — K.H. Kilburn, R. Lilis, et al. (1986)
• Cigarette smoking, asbestos, and pulmonary fibrosis — W. Weiss (1971)
• Cigarette smoking does not produce or enhance the radiologic appearance of pulmonary fibrosis — K.H. Kilburn (1981)
• Serum type III procollagen peptide: indicator for pulmonary fibrosis: II. Application in 80 asbestos insulation workers — I. Okazaki, K. Maruyama, et al. (1987)
• Diffusing capacity and forced vital capacity in 5,003 asbestos-exposed workers: relationships to interstitial fibrosis (ILO profusion score) and pleural thickening — A. Miller, R. Warshaw, et al. (2013)

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