Airborne asbestos and public health

Our plain-English summary of Airborne asbestos and public health, by D.L. Davis, B. Mandula (Annual Review of Public Health, 1985).

The study

• Authors: D.L. Davis, B. Mandula
• Journal: Annual Review of Public Health
• Published: 1985;6:195-221
• Cited by: 3 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. 004422).

In plain English

This 1985 article was a review, not a new study. The authors addressed selected issues rather than attempting a comprehensive review. They traced the US history of discovering asbestos health risks, drawing largely on a book by Castleman. They covered fiber properties, animal and epidemiologic evidence, regulations, and whether chrysotile, crocidolite and amosite differ in hazard. Of 23 occupational cohort studies published from 1977 to 1983, virtually all detected excess lung cancer. Only five showed a statistically significant gastrointestinal cancer increase, though fewer than half of the rest had power above 0.8 to detect a relative risk of 1.5. Assuming continuous exposure from birth over a 73-year lifetime, National Research Council estimates put lifetime mesothelioma risk at nine per million at a median ambient level of 0.0004 fibers per cubic centimeter (estimate range 0 to 350 per million). This risk could be considerably higher, or as low as zero, the authors cautioned. They noted that reviews diverged on whether fiber types differ in toxicity and that risk assessments are extremely uncertain. They concluded that current information calls for neither panic nor complacency, but continued vigilance.

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 human, animal, exposure and regulatory literature on asbestos (not comprehensive)
• Who was studied: Published literature, including a summary table (Table 2) of 23 occupational cohort studies of asbestos-exposed workers published between 1977 and 1983, from the US, Britain, Canada, Finland, Italy, Denmark and Australia
• Exposure: Occupational and ambient (nonoccupational) airborne asbestos, including chrysotile, crocidolite, amosite, anthophyllite and actinolite-tremolite; occupations included mining and milling, manufacturing, insulation work and shipyards
• Main results:
  • Across the 23 occupational cohort studies in Table 2, the lung cancer relative risk was high enough that virtually all studies detected it
  • For gastrointestinal cancers in the same 23 studies, only five showed a statistically significant increase. The authors noted that fewer than half of the negative studies had a power greater than 0.8 to detect a relative risk of 1.5
  • Based on these studies, the authors stated that the risk of lung cancer and mesothelioma from inhaled asbestos is greater than the risk of gastrointestinal cancer
  • The National Research Council lifetime risk estimates in Table 3 assumed continuous exposure from birth over a 73-year lifetime
  • National Research Council estimate (reported in this review): male smokers exposed for a lifetime to 0.002 fibers/cm3 (a high exposure level) would have a lifetime lung cancer risk of 320 per million, about ten times that of a nonsmoker
  • National Research Council estimate (reported in this review): among nonsmokers with lifetime exposure, mesothelioma risk is greater than lung cancer risk
  • National Research Council estimate (reported in this review): lifetime mesothelioma risk was nine per million persons exposed to a median level of 0.0004 fibers/cm3 (range of estimates 0 to 350 per million). The authors said this could be considerably higher or as low as zero, and that it was estimated to mean about 30 extra cases per year in the United States
  • In animal or in vitro experiments, no one type of asbestos appeared clearly more pathogenic than the others
  • Stanton's rat implantation experiments (reviewed here) indicated the most carcinogenic fibers were longer than 8 micrometres with diameters of 0.25 micrometres or less
  • Reviews diverged on the relative toxicity of chrysotile and crocidolite: the Ontario Commission found crocidolite more associated with mesothelioma, while the NRC found the literature unclear
• The authors' conclusion: The authors concluded that current information about health problems from ambient levels of asbestos and other fibers calls for neither panic nor complacency, but continued vigilance
• Limitations the authors state:
  • The review does not attempt to be comprehensive
  • Risk assessments depend on many assumptions and their results are extremely uncertain
  • Investigators in the underlying literature have seldom adequately characterized fiber types and sizes
  • The extrapolation models assume a dose in childhood carries the same cancer potential as one later in life, although children are often more sensitive
  • Where the increase in relative risk is small, most conventional epidemiologic studies could not detect an effect

Topics

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

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Browse more research in Annual Review of Public Health, or return to medical research.