Fiber burden and asbestos-related lung disease: determinants of dose-response relationships

Our plain-English summary of Fiber burden and asbestos-related lung disease: determinants of dose-response relationships, by M.R. Becklake, B.W. Case (American Journal of Respiratory and Critical Care Medicine, 1994).

The study

• Authors: M.R. Becklake, B.W. Case
• Journal: American Journal of Respiratory and Critical Care Medicine
• Published: 1994;150(6 Pt 1):1488-92
• Type of article: Editorial, Review
• Cited by: 42 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

This editorial discussed what measurements of asbestos fibers retained in the lung (lung burden) show about dose-response relationships for asbestos-related lung disease. It centred on two autopsy studies by Churg and colleagues from one laboratory. The first examined 94 of 300 autopsy lungs from Quebec chrysotile miners and millers, with only six controls without asbestos-related disease. The second examined 144 of 160 lungs from Pacific Northwest shipyard workers, insulators and related tradesmen with mixed amosite and chrysotile exposure, referred mainly for medico-legal purposes, with eight controls. In the miners and millers, chrysotile and tremolite burdens were higher in cases than controls for all conditions except chrysotile with pleural plaques and with lung cancer. In the shipyard series, amosite but not chrysotile burdens were associated with asbestosis and airway fibrosis. Amosite burdens in mesothelioma were much lower than in asbestosis (0.9 versus 10.0 million fibers per g). Among chrysotile workers, mesothelioma burdens were similar to or higher than asbestosis burdens. Fiber size was related only to pleural plaques. The editorialists questioned the omission of exposure data from the analyses, the small number of controls, counting methods that favored short fibers, and the conclusion about where tremolite came from. They agreed that disease potential differs by fiber type. They concluded that lung burden can confirm past exposure, but its absence or low levels cannot rule out past occupational exposure.

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 an editorial, not a new study. It discussed two autopsy lung-fiber studies by Churg and colleagues. One covered 94 of 300 autopsy lungs from Quebec chrysotile miners and millers. The other covered 144 of 160 autopsy lungs from Pacific Northwest shipyard workers, insulators and related trades with mixed amosite and chrysotile exposure. The editorial reported that the Quebec cases had higher chrysotile and tremolite burdens than controls for all conditions except two: chrysotile with pleural plaques and chrysotile with lung cancer. In the Pacific series, amosite burdens, but not chrysotile burdens, were associated with asbestosis and airway fibrosis. Mesothelioma cases there carried much less amosite than asbestosis cases (0.9 versus 10.0 million fibers per gram of lung tissue). The editorial authors criticised the very small control groups (six and eight subjects), the omission of exposure data from the analysis, and counting methods that favored short fibers. They concluded the studies added weight to evidence that fiber types differ in disease-producing potential. They also noted that lung fiber burden can confirm past exposure, but a low or absent burden cannot rule out past occupational 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: editorial commenting on two autopsy case series (lung fiber burden studies) by Churg and colleagues; no new data
• Who was studied: As described in the editorial: 94 of 300 autopsy lungs from Quebec chrysotile miners and millers, and 144 of 160 autopsy lungs from shipyard workers, insulators and related tradesmen in the Pacific Northwest
• Exposure: Chrysotile (with tremolite contaminant) in the Quebec miners and millers; mixed amosite and chrysotile in the Pacific Northwest shipyard trades
• Main results:
  • Quebec chrysotile miners and millers: cases had higher chrysotile and tremolite burdens than controls for all conditions. The exceptions were chrysotile with pleural plaques and chrysotile with lung cancer.
  • Pacific shipyard trades: amosite burdens, but not chrysotile burdens, were associated with asbestosis and airway fibrosis. Mesothelioma cases had a much lower amosite burden than asbestosis cases (0.9 versus 10.0 million fibers per g lung tissue).
  • Quebec chrysotile workers: mesothelioma cases had burdens similar to or higher than asbestosis cases, both for tremolite (180 versus 140 million fibers per g lung tissue) and for chrysotile (34 versus 30 million fibers per g lung tissue).
  • In the Quebec study, fiber size relationships were not apparent, except that tremolite length and aspect ratio were related to pleural plaques. In the Pacific study, aspect ratio was the only size variable associated with disease, and only for pleural plaques.
  • The editorial authors stated that in an individual case, lung fiber burden can confirm past exposure, but its absence or a low level cannot rule out past occupational exposure.
• The authors' conclusion: The editorial authors concluded that the main contribution of the two studies was adding weight to existing evidence that different asbestos fiber types have different disease-generating potential.
• Limitations the authors state:
  • Only six unmatched controls in the Quebec series
  • The no-disease comparison group in the Pacific series was only eight men
  • Exposure information was not included in the analyses of either study
  • Because of autopsy selection, the 94 Quebec cases were not representative of all workers
  • The Pacific cases were referred mainly for medico-legal purposes
  • The fiber size selection used in the studies favored counting short fibers
  • Crocidolite was excluded, so the studies cannot address amosite versus crocidolite potency

Topics

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

Medical terms in this study, explained in our Lexicon: Fiber Burden, Dose-response relationship, Autopsy, Quebec Chrysotile, Insulator, Amosite, Chrysotile, Tremolite.

Related studies

• Dose-response relationships for asbestos-related disease: implications for hygiene standards. Part II. Mortality — J. Peto (1979)
• Dose-response relationship of fibrous dusts in intraperitoneal studies — M. Roller, F. Pott, et al. (1997)
• A study of dose-response relationships for asbestos associated disease — M.M. Finkelstein (1985)
• Asbestos and other fiber-related diseases of the lungs and pleura. Distribution and determinants in exposed populations — M.R. Becklake (1991)
• Evaluation of the exposure, dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos in a 90-day quantitative inhalation toxicology study - Interim results Part 1: Experimental design, aerosol exposure, lung burdens and BAL — D.M. Bernstein, B. Toth, et al. (2020)
• Asbestos exposure and benign asbestos diseases in 772 formerly exposed workers: dose-response relationships — G. Mastrangelo, M.N. Ballarin, et al. (2009)

Browse more research in American Journal of Respiratory and Critical Care Medicine, or return to medical research.