Asbestosis Fact and Fancy

Our plain-English summary of Asbestosis Fact and Fancy, by W.C. Cooper (1967).

The study

• Author: W.C. Cooper
• Published: February 1, 1967
• Type of article: Conference paper
• 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 is the text of a talk, marked "Final Draft February 1, 1967," prepared for the American Academy of Occupational Medicine in San Francisco on February 8, 1967. It is a narrative review of the health effects of asbestos, not a new study, and mostly discusses other researchers' work. On asbestosis, the author drew on others' textile and shipyard observations to argue that the threshold limit value then in use, a dust count of 5 mppcf, was too high. The author added that the author's own studies of insulating workers agreed with shipyard counts that did not average above that level. The author called increased lung cancer in many groups of asbestos-exposed workers a fact. The author said it was not known whether the link was weaker for chrysotile than for crocidolite and amosite. For pleural and peritoneal mesothelioma, the author judged the evidence strongest for crocidolite, especially Cape blue crocidolite. Autopsy studies had found so-called asbestos bodies in people without known exposure, but no study had yet shown what these bodies were made of. The author found it unwarranted to conclude that they foretold an epidemic of tumors. The author concluded that dust standards did not appear adequate to prevent asbestosis over a working lifetime.

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 given as a lecture: a talk surveying published evidence on the health effects of asbestos, with no new study of its own
• Who was studied: No study population of its own. The talk discusses other researchers' studies of asbestos miners, millers, textile workers, shipyard insulating workers, and autopsy series from the general population. The author also mentions the author's own studies of insulating workers but gives no details.
• Exposure: Asbestos in general, with discussion of chrysotile, amosite, crocidolite (including Cape blue crocidolite) and anthophyllite. Dust levels are measured as mppcf and compared against the threshold limit value of 5 mppcf.
• Main results:
  • Based on others' observations in textiles and shipyards and on the author's own studies of insulating workers, the author judged that a time-weighted average of 5 mppcf was too high to control asbestosis.
  • The author described increased lung cancer in many groups of asbestos-exposed workers as a fact, resting on cumulative epidemiologic evidence from other studies.
  • The author stated that it was not known whether the association with lung cancer was truly weaker for chrysotile than for crocidolite and amosite.
  • For diffuse pleural and peritoneal mesothelioma, the author judged the evidence strongest for crocidolite, especially Cape blue crocidolite.
  • Citing a 1966 report by Raunio, the author stated that anthophyllite did not appear to be a problem in this respect. In that report, high rates of pleural calcification in Finnish anthophyllite mining areas were not associated with more lung cancer or malignant pleural or peritoneal tumors.
  • Other studies found so-called asbestos bodies (also called ferruginous bodies) in consecutive autopsies; for example, Thomson et al. reported them in 26.4% of 500 autopsies in Cape Town. The author noted that no published study had shown whether all, most or some of these bodies were asbestos. The author considered it unwarranted to conclude that they foretold an epidemic of tumors.
• The authors' conclusion: The author concluded that dust control standards then in use did not appear adequate to prevent asbestosis over a working lifetime. The author also concluded that the links between asbestos and malignancies of the lungs, pleura and peritoneum were becoming increasingly convincing. Finally, the author called for urgent positive identification of the mineral fibers found in autopsy lungs.
• Limitations the authors state:
  • The author noted that the midget impinger dust counts behind the 5 mppcf limit include all dusts and miss many asbestos fibers too thin to see with a light microscope.
  • The author noted that death certificate data on mesothelioma were misleading because of incorrect diagnoses.
  • The author noted that no published autopsy study had shown whether all, most or some of the bodies counted were actually asbestos.

Topics

Medical terms in this study, explained in our Lexicon: Threshold Limit Value (TLV), Million Particles per Cubic Foot (mppcf), Lung Cancer, Chrysotile, Crocidolite, Amosite, Peritoneal Mesothelioma, Cape Blue.

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