Asbestos: The Need For And Feasibility Of Air Pollution Controls

Our plain-English summary of Asbestos: The Need For And Feasibility Of Air Pollution Controls, by W.C. Cooper, L.J. Cralley, B.G. Ferris, et al (1971).

The study

• Authors: W.C. Cooper, L.J. Cralley, B.G. Ferris, Jr, P. Gross, D.A. Holaday, I.J. Selikoff, G.W. Wright, S.P. Hicks, T.D. Boaz, Jr
• Published: Washington, Dc: National Academy Of Sciences, Pp. 1-40 (1971)
• Type of article: Report
• Our copy: from Johns-Manville's own medical library, J-M no. 002787. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1971 National Research Council panel report was a review of published evidence, not a new study. It was requested by the National Air Pollution Control Administration. It covered how asbestos causes disease, nonoccupational exposure, sources of airborne asbestos, and controls. The authors concluded that any commercially used asbestos mineral, inhaled in sufficient numbers as in uncontrolled workplace exposure, can cause disabling lung fibrosis. They judged the association between occupational exposure and bronchogenic carcinoma established, and evidence of a causal link between some but not all exposures and diffuse malignant mesothelioma of the pleura and peritoneum substantial. They regarded no asbestos type as free of hazard. Among people not working directly with asbestos, they placed the major potential risk in those with indirect occupational contacts, household contacts, or residence in the immediate neighborhood of an asbestos source, though the risk was poorly defined. They found no evidence that the small fiber numbers in most people affect health. They judged further contamination of public air highly imprudent and emission controls needed and apparently feasible, but methods and data inadequate for an ambient air standard.

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: Expert committee review report (National Academy of Sciences, National Research Council, Panel on Asbestos) summarizing published evidence on asbestos as an air pollutant: health effects, sources, measurement and feasibility of control
• Who was studied: No new study population. The report reviewed published studies, mostly of occupational groups (asbestos mining and milling, manufacture of asbestos products, insulation work). It also reviewed studies of household and neighborhood contacts, autopsy series from the general population, and experimental animals.
• Exposure: Asbestos in general and the six commercially important types: chrysotile (a serpentine, 95% of world production) and the amphiboles amosite, crocidolite, anthophyllite, tremolite and actinolite. Exposures ranged from occupational to household, neighborhood and general ambient air.
• Main results:
  • The authors concluded that any commercially used asbestos mineral, inhaled in sufficient numbers as in uncontrolled occupational exposures, can cause disabling fibrosis of the lungs.
  • An association between occupational exposure to asbestos and bronchogenic carcinoma was judged established. The dose-response relation and the role of cofactors had not been defined.
  • Evidence of a causal association between some but not all asbestos exposures and diffuse malignant mesotheliomas of the pleura and peritoneum was judged substantial. Evidence for other tumors was judged inconclusive.
  • Although the asbestos types differ in some biologic effects, no type was regarded as free of hazard.
  • Ferruginous bodies resembling those in asbestos workers, found in a large proportion of randomly selected lung specimens, were taken as presumptive evidence that people with no occupational contact may have inhaled asbestos. Chrysotile was positively identified in some areas.
  • Industrial experience was taken to indicate no likelihood of significant asbestosis from nonoccupational exposures.
  • In the report's discussion of nonoccupational exposures, the major potential for risk appeared to lie in people with indirect occupational contacts, household contacts, or residence in the immediate neighborhood of an asbestos source. Even there, the actual risk was poorly defined.
  • There was no evidence that the small numbers of fibers found in most members of the general population affect health or longevity.
• The authors' conclusion: The authors concluded that it would be highly imprudent to permit additional contamination of the public environment with asbestos. They concluded that major man-made emission sources should be defined and controlled, and that emission controls are needed and appear feasible, although an ambient air standard could not yet be developed.
• Limitations the authors state:
  • The report states that it is not a state-of-the-art document and does not attempt to cover fully all that is known about asbestos.
  • Direct epidemiologic studies of nonoccupationally exposed groups were few and inadequate to answer the questions at issue.
  • Methods for sampling, identifying and measuring airborne asbestos were not entirely satisfactory, especially at low concentrations and with unidentified or mixed sources.
  • Analytic methods and epidemiologic data were not yet adequate for developing an ambient air standard.

Topics

Medical terms in this study, explained in our Lexicon: Fibrosis, Occupational Exposure, Bronchogenic Carcinoma, Malignant Mesothelioma, Pleura, Peritoneum.

Browse return to medical research.