Asbestos as a public health risk: disease and policy

Our plain-English summary of Asbestos as a public health risk: disease and policy, by H. Weill, J.M. Hughes (Annual Review of Public Health, 1986).

The study

• Authors: H. Weill, J.M. Hughes
• Journal: Annual Review of Public Health
• Published: 1986;7:171-92
• Type of article: Review
• Cited by: 19 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. 000447).

In plain English

This article was a review and policy commentary, not a new study of workers or patients. The authors summarized published asbestos research and discussed US risk reduction, workplace standards and compensation. Citing other studies, they reported that lung cancer dose-response slopes varied by industry: steepest in textile work, shallowest in mining and friction products. They cited a Canadian expert report: mesothelioma cases equaled 12% of excess lung cancers in chrysotile-only populations, 22% for amosite, 165% for crocidolite and 66% for mixed fibers. They compared published risk estimates for students in schools with friable asbestos, adjusted to 0.001 fibers per milliliter of mixed fibers for five school years from age 10. These were 1.9 to 21.9 asbestos-attributable cancer deaths per million students over a lifetime, averaging 0.03 to 0.37 per million yearly when spread over an assumed 60 remaining years. The authors wrote that this was below many other published risks and that testimony implying an overwhelming risk to schoolchildren was not supported by the evidence. They noted that such estimates carry considerable uncertainty because they are extrapolated from high past exposures.

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 and policy commentary on asbestos health risks and US policy. It includes the authors' comparison of published school-exposure risk estimates, adjusted to common assumptions. It reports no new data on workers or patients.
• Who was studied: No study population of its own. The authors drew on published epidemiologic studies of asbestos-exposed workers (textile, asbestos cement, manufacturing, friction products, mining, insulators). They also used published risk assessments for students in US schools with friable asbestos products, and the history of US standards and compensation.
• Exposure: Chrysotile, amosite, crocidolite and mixed-fiber exposures in industry. The school scenario assumed an average of 0.001 fibers per milliliter of mixed fibers, 35 hours per week, 36 weeks per year, for five years beginning at age 10.
• Main results:
  • From seven published worker cohorts: the slope of the lung cancer dose-response relationship varied by industrial process. Textile workers had the steepest slope, asbestos cement and other manufacturing workers intermediate slopes, and miners and friction product workers the shallowest.
  • Citing a summary by a Canadian committee of experts (ref. 8): mesothelioma cases equaled 12% of excess lung cancers in populations exposed only to chrysotile, 22% for amosite and 165% for crocidolite. Cohorts exposed to mixed fibers had an intermediate value of 66%.
  • The authors interpreted these figures as suggesting that chrysotile may pose about one fifth the mesothelioma risk of mixed-fiber exposure.
  • Published estimates adjusted to the school scenario (0.001 fibers per milliliter of mixed fibers, five school years) ranged from 1.9 to 21.9 per million students exposed. Table 1 defines these as estimated total deaths over a lifetime attributable to asbestos exposure.
  • The authors assumed an average life expectancy of 75 years, which leaves 60 years beyond school exposure. Dividing the lifetime death estimates by those 60 years gave an average annual rate of 0.03 to 0.37 deaths per million. This is an arithmetic average, not an estimated constant yearly risk.
  • The authors' own estimates (ref. 22a) for the school scenario, per one million students, were 0.5 to 1.6 lung cancer deaths, 1.8 to 5.4 mesothelioma deaths and 2.3 to 7.0 total.
  • EPA draft reports first estimated 100 to 8000 premature deaths from school asbestos exposure. The next draft reduced this to 40 to 400, and the draft after that gave no estimate, all on the same exposure assumptions.
  • Citing other work: asbestosis has been seen at recent industrial exposure levels, generally mild. The authors stated there is no evidence that asbestosis can result from environmental exposures.
  • In 1983 OSHA issued an emergency temporary standard lowering the permissible exposure level to 0.5 fibers. A court panel found it not justified. Hearings on a proposal of 0.2 or 0.5 fibers per milliliter were held in 1984, and no permanent rule had been issued at the time of writing.
  • The authors stated their view that claims based only on pleural plaques, or on chronic airways obstruction, do not represent occupationally induced disease. They described pleural plaques as having no documented effect on respiratory health.
• The authors' conclusion: The authors concluded that rational policy on asbestos risk reduction and worker compensation can be based on existing scientific knowledge. They held that the implication of an overwhelming risk to schoolchildren was not supported by the evidence. They proposed that compensation rest on uniform medical guidelines set by a national panel of experts.
• Limitations the authors state:
  • Cancer risks at today's lower exposures are extrapolated from past high exposures, which makes the estimates considerably uncertain, especially for environmental levels.
  • Few studies have quantitative dose information for mesothelioma, so there is only limited information on which to base a dose-response relationship.
  • The evidence for different mesothelioma risk by fiber type is not wholly conclusive without a fiber-for-fiber comparison controlling for total exposure, which past exposure data do not allow.

Topics

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

Related studies

• Rural public health policy models to address an evolving environmental asbestos disaster — S.W. Kuntz, C.A. Winters, et al. (2009)
• Asbestos-associated diseases. Science, public policy, and litigation — H. Weill (1983)
• Asbestos in the air of public buildings: a public health risk? — J. Whysner, V.T. Covello, et al. (1994)
• Asbestos: the turbulent interface between science and policy — J.B. Gee (1992)
• Asbestos: the turbulent interface between science and policy — K. Morgan (1992)
• Comments on the Health Effects Institute-Asbestos Research (HEI-AR) report: "Asbestos in public and commercial buildings," with emphasis on risk assessment methods used — T.D. Sterling, C.W. Collett, et al. (1993)

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