Asbestos as a Hazard to Health: Fact and Speculation

Our plain-English summary of Asbestos as a Hazard to Health: Fact and Speculation, by W. Clark Cooper (1967).

The study

• Author: W. Clark Cooper
• Published: Archives of Environmental Health, vol 15 (Sept 1967); read before the 19th annual meeting of the American Academy of Occupational Medicine, San Francisco, Feb 8, 1967
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1967 paper by W. Clark Cooper, published in Archives of Environmental Health, was a talk given to the American Academy of Occupational Medicine. It reviewed existing evidence and was not a new study. The author surveyed published reports on asbestosis, cancers, and "ferruginous" (asbestos-like) bodies in lungs. The author wrote that no one disputed that asbestos causes asbestosis. The author also argued that the dust limit then recommended, 5 million particles per cubic foot, did not appear adequate to prevent asbestosis over a working lifetime. The author called the increase in lung cancer in many groups of asbestos workers a fact. The role of different fiber types was unclear, with chrysotile less certainly implicated. For pleural and peritoneal mesothelioma, the author judged the evidence strongest for crocidolite. Routine autopsy series had found such bodies in a quarter to a half of lungs. The author stated that no study had shown whether they were asbestos, and that it was unwarranted to conclude they foretold an epidemic of tumors. The author called for better study of fiber type, fiber size and co-factors.

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 evidence, presented as a talk at a medical society meeting; not an original study
• Who was studied: No study population of its own; the author reviewed published epidemiologic studies of asbestos-exposed workers, autopsy series, and animal experiments
• Exposure: Asbestos minerals of commerce: chrysotile, crocidolite, amosite and anthophyllite, with tremolite and actinolite of less importance; dust limit of 5 million particles per cubic foot discussed
• Main results:
  • The author stated that a cause-and-effect relationship between asbestos and asbestosis is undisputed
  • The author judged that the threshold limit value of 5 million particles per cubic foot did not appear adequate to prevent asbestosis over a working lifetime
  • The author called an increased incidence of lung cancer in many groups of asbestos-exposed workers a fact
  • In the author's view, the evidence on the relative importance of fiber types for lung cancer was not convincing; chrysotile seemed less certainly implicated
  • For diffuse pleural and peritoneal mesothelioma, the author judged the evidence strongest for crocidolite, especially Cape blue crocidolite
  • Ferruginous bodies had been found in one-quarter to one-half of lungs in consecutive autopsy series in several cities; the author stated no published study had shown whether these bodies were asbestos
  • The author wrote that it was unwarranted to conclude that these bodies necessarily presage an epidemic of neoplasms
• The authors' conclusion: The author concluded that dust standards appeared inadequate, that associations with lung, pleural and peritoneal malignancies had become increasingly convincing, and that efforts should focus on fiber type, fiber size, co-factors, and identifying the fibers in ferruginous bodies
• Limitations the authors state:
  • The author noted that the impinger dust counts underlying the standard counted mainly grains and missed fibers too thin for the light microscope
  • The author noted that the autopsy series were small

Topics

Medical terms in this study, explained in our Lexicon: Million Particles per Cubic Foot (mppcf), Lung Cancer, Chrysotile, Peritoneal Mesothelioma, Crocidolite, Autopsy.

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