Health effects of asbestos and nonasbestos fibers

Our plain-English summary of Health effects of asbestos and nonasbestos fibers, by O.Y. Osinubi, M. Gochfeld, H.M. Kipen (Environmental Health Perspectives, 2000).

The study

• Authors: O.Y. Osinubi, M. Gochfeld, H.M. Kipen
• Journal: Environmental Health Perspectives
• Published: 2000;108 Suppl 4(Suppl 4):665-74
• Type of article: Review
• Cited by: 24 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Exposures to asbestos and synthetic fibers remain areas of great concern in the field of occupational lung disease. Despite extensive study, the health effects associated with fibers remains an area of substantial controversy. In particular, effects of fibers at relatively low doses, particularly for mesothelioma, remain a matter of evolving opinion, especially when integrated with the divergence of opinion on relative pathogenicity of different fiber types. Mechanistic studies continue to provide a window into pathogenesis and some hope for understanding dose-response relationships at the lower levels seen in contemporary Western workplaces and the general environment. Changes in clinical assessment based on use of new chest imaging techniques beyond the traditional plain film are also an area of evolution and begin to challenge B-reading as the definitive tool for noninvasive assessment of disease. Public health concerns have to a great extent been transported to the developing world where there is a strong trend toward increased use of asbestos, although it has been virtually eliminated from commerce in most developed countries. For nonasbestos fibers, the major unsettled issues are their relative potencies as carcinogens for the human lung and mesothelium and the need to sort out the relation between physical and chemical properties of these fibers and their pathogenicity. The recent discovery of "flock worker's lung" due to synthetic fibers once again alerts us to emerging diseases associated with new technologies.

In plain English

This article was a review, not new research. The authors examined published research, mainly from the 1990s, on lung and pleural disease linked to asbestos, zeolites, man-made vitreous fibers (MMVFs, including refractory ceramic fibers, or RCFs) and nylon flock. On asbestos, they agreed with earlier reviewers that lung burden studies gave insufficient basis for discounting chrysotile as a cause of fibrosis or mesothelioma. They judged the evidence insufficient to conclude that asbestosis must precede asbestos-related lung cancer. They described a case-control study of pleural mesothelioma and asbestos exposure by Iwatsubo and colleagues, which reported an odds ratio of 1.2 (0.8-1.8) in its low-exposure category and 8.7 (4.1-18.5) in its high-exposure category. On MMVFs, they wrote that one cohort gave substantial evidence that RCFs caused pleural plaques. They also wrote that significant human cancer risk from any inhaled MMVF was neither clearly established nor refuted. They described "flock worker's lung", interstitial lung disease reported among workers at a Rhode Island nylon flocking plant. The authors concluded that exposure levels below which there is no appreciable risk had yet to be defined.

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: narrative review of published literature
• Who was studied: Published studies (human, animal and laboratory), with a focus on work published in the last decade of the 20th century
• Exposure: Asbestos fibers (including chrysotile and amphiboles such as crocidolite, amosite and tremolite), zeolites, man-made vitreous (mineral) fibers, and nylon flock
• Main results:
  • The authors agreed with Stayner et al. that lung burden studies of different fiber types do not clearly support a strong gradient in ability to cause fibrosis and mesothelioma. In their view these studies give insufficient basis for discounting chrysotile as a cause of either condition.
  • The authors judged the evidence insufficient to conclude that pulmonary fibrosis (asbestosis) is a necessary antecedent of carcinogenic risk from asbestos.
  • The review described the case-control study of pleural mesothelioma and asbestos exposure by Iwatsubo et al. That study reported an odds ratio of 1.2 (0.8-1.8) for its low-exposure category and 8.7 (4.1-18.5) for its high-exposure category.
  • The authors wrote that there is substantial evidence in at least one cohort that refractory ceramic fibers (RCFs) caused pleural plaques.
  • The authors wrote that significant human carcinogenic risk from any inhaled MMVF is neither clearly established nor refuted.
  • The review described a 1998 report of interstitial lung disease among workers at a Rhode Island nylon flocking plant.
• The authors' conclusion: The authors concluded that fiber type, size, intensity and duration of exposure contribute to disease. They also concluded that practical exposure levels below which there is no appreciable risk had yet to be defined.
• Limitations the authors state:
  • The authors stated that a detailed account of fiber disease mechanisms was beyond the scope of the article.
  • The authors did not consider animal bioassays of asbestos.

Topics

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

Medical terms in this study, explained in our Lexicon: Occupational Lung Disease, Mesothelioma, Dose-response relationship, Mesothelium, Discovery.

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• Factors that impact susceptibility to fiber-induced health effects — J.E. Below, N.J. Cox, et al. (2011)
• An evaluation of the risks of lung cancer and mesothelioma from exposure to amphibole cleavage fragments — J.F. Gamble, G.W. Gibbs (2008)
• Mesothelioma and asbestos — G.W. Gibbs, G. Berry (2008)
• Industrial-grade talc exposure and the risk of mesothelioma — B. Price (2010)

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