Cigarette smoking does not produce or enhance the radiologic appearance of pulmonary fibrosis

Our plain-English summary of Cigarette smoking does not produce or enhance the radiologic appearance of pulmonary fibrosis, by K.H. Kilburn (American Journal of Industrial Medicine, 1981).

The study

• Author: K.H. Kilburn
• Journal: American Journal of Industrial Medicine
• Published: 1981;2(3):305-8
• Cited by: 15 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. 000752).

Summary of the article

This commentary asked whether long-term cigarette smoking produced chest X-ray changes that resembled, or could be confused with, pneumoconiosis, including asbestosis. The author critically reviewed published studies. In two studies by Weiss using 70 mm photofluorograms, more smokers than nonsmokers were reported to have prominent bronchovascular markings: 4.2% of current smokers and 14.3% of 98 heavy smokers versus 1.5% of 393 nonsmokers, and, among 2,825 adults, 1.9% of smokers versus 0.6% of nonsmokers. The author argued that these markings did not define interstitial fibrosis, that ILO criteria were not used, and that small films reduced resolution. Only half of the 70 mm films read as fibrosis were confirmed on full-size films. In a chrysotile textile mill study, 57% of smokers (16 of 28) versus 43% of nonsmokers had fibrosis, which the author said was not a statistical difference. A study of 88 workers in two asbestos plants had very small numbers. A larger study of 383 subjects by Samet et al found the same exposure-response relationship regardless of smoking. A study in 20 British collieries found similar pneumoconiosis prevalence in smokers (30.2%) and nonsmokers (29.8%). The smoking beagle studies showed emphysema and small airways disease, not fibrosis. The author concluded that cigarette smoking neither produced radiographic pulmonary fibrosis nor contributed to fibrosis from asbestos or coal dust.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This article was a commentary, not a new study. The author reviewed earlier studies, mainly by Weiss, suggesting that cigarette smoking causes X-ray changes resembling pulmonary fibrosis or adds to asbestosis. The author argued that Weiss's two earliest studies used miniature 70 mm photofluorograms read without standard ILO criteria, and that the later chrysotile textile mill study used full-size films but still not the ILO definition. The author said the definitions relied on prominent bronchovascular markings, which do not define diffuse interstitial fibrosis. Only about half of a sample of 70 mm films read as fibrosis were judged fibrosis on full-size films. For mill workers said to have 20 or more years of asbestos exposure (durations were estimated roughly from ages, as no exposure start dates were given), 16 of 28 smokers (57%) had fibrosis, against 6 of 14 nonsmokers (43%), not a statistical difference. The author cited a larger study (383 subjects, Samet and colleagues) with opposite conclusions. The author concluded that smoking neither produces X-ray-visible fibrosis nor adds to fibrosis from asbestos or coal dust.

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: Commentary (critical review of previously published studies); no new data
• Who was studied: No population of its own. The author reviewed published studies: Weiss 1967 (1,000 photofluorograms) and 1969 (2,825 adults), Weiss 1971 (workers in a chrysotile textile mill), Weiss and Theodos 1978 (88 workers in two asbestos products plants), Samet et al 1979 (383 subjects), a study in 20 British collieries, and a study of 92 women at a New Jersey hospital
• Exposure: Cigarette smoking, alone and combined with asbestos exposure (including chrysotile in a textile mill) or coal dust
• Main results:
  • In the Weiss 1969 study, 5 of 839 nonsmokers and 35 of 1,860 smokers had the X-ray findings (0.6% vs 1.9%). The author argued that applying the known reading errors would cut the frequencies by about two-thirds and the difference between groups would disappear.
  • In the author's account, only half of a sample of 70 mm films read as fibrosis were thought to show fibrosis when full-size 14 by 17 inch films of the same subjects were examined.
  • The author stated that the Weiss 1971 textile mill study, although it used full-size 14 by 17 inch films, again did not use the ILO definition of fibrosis.
  • The author noted that the Weiss 1971 mill study gave no data on the date of first asbestos exposure, so workers could be grouped only roughly, by age, into under 20 years, 20 to 30 years, and over 30 years from first exposure.
  • In the comparison the author discussed from the Weiss 1971 chrysotile textile mill study, which concerned workers described as having 20 years or more of asbestos exposure, 16 of 28 asbestos-exposed smokers (57%), regardless of pack-years, had fibrosis, compared with 6 of 14 nonsmokers (43%). The author described this as not a statistical difference.
  • A larger study of 383 subjects by Samet et al found the same regression of X-ray score on asbestos exposure in 58 nonsmokers, 11 past smokers and 207 present smokers. That study concluded smoking had no effect on X-ray signs of asbestosis.
  • In a cited study of 20 British collieries, the prevalence of coal workers' simple pneumoconiosis was 30.2% in 2,675 smokers and 29.8% in 704 nonsmokers.
  • The author stated that the smoking-beagle experiments by Auerbach et al showed emphysema and small airways disease, not fibrosis.
• The authors' conclusion: The author concluded that the answer is no both to whether cigarette smoking produces pulmonary fibrosis as judged by chest X-ray, and to whether it contributes to fibrosis due to asbestos or coal workers' pneumoconiosis.

Topics

Medical terms in this study, explained in our Lexicon: Pulmonary Fibrosis, Chest X-Ray, Pneumoconiosis, Interstitial Fibrosis, Fibrosis, Chrysotile, Emphysema.

Related studies

• 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)
• Asbestosis: interstitial pulmonary fibrosis and pleural fibrosis in a cohort of asbestos insulation workers: influence of cigarette smoking — R. Lilis, I.J. Selikoff, et al. (1986)
• Smoking-associated fibrosis and pulmonary asbestosis — J.R. Bledsoe, D.C. Christiani, et al. (2015)
• Radiographic abnormalities in asbestos insulators: effects of duration from onset of exposure and smoking. Relationships of dyspnea with parenchymal and pleural fibrosis — R. Lilis, A. Miller, et al. (1991)
• Pulmonary function and pleural fibrosis: quantitative relationships with an integrative index of pleural abnormalities — R. Lilis, A. Miller, et al. (1991)

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