Asbestos fiber content of the lungs in patients with and without asbestos airways disease

Our plain-English summary of Asbestos fiber content of the lungs in patients with and without asbestos airways disease, by A. Churg (The American Review of Respiratory Disease, 1983).

The study

• Author: A. Churg
• Journal: The American Review of Respiratory Disease
• Published: 1983;127(4):470-3
• Cited by: 48 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

I analyzed the total pulmonary asbestos burden in the lungs of 9 chrysotile miners who had asbestos airways disease (so-called "early asbestosis") but no evidence of classic asbestosis (interstitial fibrosis) on pathologic examination. The results were compared with values found for 9 miners matched for age, sex, smoking, and work length who had no histologic evidence of asbestosis or asbestos airways disease. The mean value for chrysotile fibers in the airway disease group was 47 X 10(6)/g dried lung, compared with 23 X 10(6) in the group without lesions (p less than 0.04). For contaminant amphiboles, probably derived from the chrysotile ore (tremolite, actinolite, anthophyllite), the corresponding values were 106 X 10(6) versus 58 X 10(6) (p less than 0.06), and for total asbestos fibers, 153 X 10(6) versus 81 X 10(6) (p less than 0.06). There was a strong correlation between amount of chrysotile and amphibole for each case, suggesting that the amphibole was probably a good measure of the original (but no longer present) chrysotile burden. No differences were seen between the 2 groups with regard to fiber size distribution, aspect ratios, or fiber widths. I conclude that the overall differences in fiber concentration between the 2 groups, although significant, are sufficiently small enough to suggest that other factors may be involved in the genesis of small airway lesions.

In plain English

This study examined autopsy lungs from Quebec chrysotile mine industry workers, all men. The author compared 9 workers who had asbestos airway lesions (scarring of the small airways, sometimes called "early asbestosis") but no interstitial fibrosis (classic asbestosis) with 9 workers who had neither. The two groups were matched for age, smoking and years of employment. Lung tissue was dissolved, and the fibers were counted and identified by electron microscopy. The airway lesion group averaged 47 million chrysotile fibers per gram of dry lung, against 23 million in the comparison group (p less than 0.04). For contaminant amphiboles from the ore (tremolite, actinolite, anthophyllite), the figures were 106 million versus 58 million (p less than 0.06). The author called these differences marginally significant. Fiber sizes, length-to-width ratios and widths did not differ between the groups. Pleural plaques were found in 6 of the 9 airway lesion cases and 3 of the 9 comparison cases. The author concluded that the differences, although significant, were small enough to suggest that other factors may be involved in causing the airway lesions. The author noted it could not be known how well the groups were matched for dust exposure.

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: Autopsy lung study comparing lung asbestos fiber content in workers with asbestos airway lesions against matched workers without such lesions
• Who was studied: 18 male Quebec chrysotile mine industry workers, selected from about 40 autopsy lungs. Nine test cases had asbestos airway lesions without interstitial fibrosis. Nine controls had neither, and were matched by sex, age within 7 years, smoking within 10 pack-years, and employment within 5 years. Most were described as miners. Dates are not given.
• Exposure: Work in chrysotile mining, with contaminant amphiboles (tremolite, actinolite, anthophyllite) from the chrysotile ore. Mean years of exposure were 34 for the airway lesion group and 32 for the control group.
• Main results:
  • Chrysotile fibers: 47 x 10^6 per gram of dried lung in the airway lesion group versus 23 x 10^6 in the group without lesions (p less than 0.04).
  • Contaminant amphiboles: 106 x 10^6 versus 58 x 10^6 per gram (p less than 0.06). Total asbestos fibers: 153 x 10^6 versus 81 x 10^6 per gram (p less than 0.06). The author described the values as marginally significant.
  • Mean asbestos bodies were 46,000 in the test group and 20,000 in the control group. This difference was not significant.
  • Chrysotile and contaminant amphibole counts were strongly correlated: rho = 0.88 in the test group and rho = 0.78 in the control group.
  • Fiber size distribution, aspect ratios and fiber widths did not differ between the test and control groups.
  • There were no significant differences in fiber concentration between peripheral and central lung samples in either group.
  • Lung cancer was present in 3 of the airway lesion group and 4 of the control group. Pleural plaques were present in 6 of the test group and 3 of the control group (9 per group).
• The authors' conclusion: The author concluded that the differences in fiber concentration between the groups, although significant, were small enough to suggest that other factors may be involved in causing small airway lesions.
• Limitations the authors state:
  • No detailed job or dust level histories were available, so how well the groups were matched for dust exposure is unknown.
  • Chrysotile disappears from the lung over time, so the measured counts markedly underestimate earlier chrysotile burden.
  • The numbers of cases with plaques and lung cancer are small.
  • The sampling used relatively large pieces of lung, so local fiber concentrations near the respiratory bronchioles may not have been captured.

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Interstitial Fibrosis, Amphibole Group, Tremolite, Actinolite, Anthophyllite, Aspect Ratio (Length-to-diameter ratio).

Related studies

• Mineral fiber content of lungs in patients with mesothelioma seeking compensation in Québec — A. Dufresne, R. Bégin, et al. (1996)
• A comparison of the ferruginous body and uncoated fiber content in the lungs of former asbestos workers — R.F. Dodson, M.G. Williams, et al. (1985)
• Discrepancies of asbestos body and fiber content between formalin-fixed and corresponding paraffin embedded lung tissue — B.K. Kuhn, F. Barresi, et al. (2021)
• Asbestos fiber burdens in lung tissues of Hong Kong Chinese with and without lung cancer — Y. Liu, P. Zhang, et al. (2001)
• Asbestos content of lung tissue in asbestos associated diseases: a study of 110 cases — V.L. Roggli, P.C. Pratt, et al. (1986)
• Correlation between fibre content of the lung and disease in east London asbestos factory workers — J.C. Wagner, M.L. Newhouse, et al. (1988)

Browse more research in The American Review of Respiratory Disease, or return to medical research.