Environmental Pulmonary Carcinogens

Our plain-English summary of Environmental Pulmonary Carcinogens, by R.L.H. Murphy (1977).

The study

• Author: R.L.H. Murphy
• Published: Proposed Report of Committee on Environmental Health, American College of Chest Physicians (1977)
• Type of article: Report
• 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 was a proposed report dated October 22, 1977, prepared by Raymond L.H. Murphy, Jr. for the Committee on Environmental Health, American College of Chest Physicians. It was a review compiling substances that recognized authorities reported as human lung carcinogens, largely on epidemiologic evidence. The report stated that most authorities agreed asbestos, chromium, nickel, arsenic and ionizing radiation were carcinogenic to humans, although its table placed arsenic among other implicated substances. It noted open questions about the relative carcinogenicity of different asbestos fiber types.

It quoted conclusions of the International Agency for Research on Cancer. That agency found lung carcinoma and mesothelioma risk small in chrysotile mines and mills, possibly also for amosite, while some crocidolite mining areas had higher mesothelioma risk. In manufacturing and application industries, mesotheliomas had been caused by crocidolite, less often by amosite and chrysotile. Tumors usually developed more than 30 years after first exposure, and smoking raised lung carcinoma risk in asbestos workers far more than in others. The report concluded that a complete list of lung carcinogens was then impossible.

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: Review: a proposed committee report compiling substances that recognized authorities had listed as human lung carcinogens, largely on epidemiologic grounds
• Who was studied: No study population. The report reviewed published lists and reports by recognized authorities, including the International Agency for Research on Cancer monographs, on occupational and environmental causes of lung cancer in humans.
• Exposure: Occupational and environmental substances implicated in lung cancer: asbestos, chromium, nickel, arsenic, ionizing radiation, tar, soot and smoke (including polycyclic aromatic hydrocarbons), hematite and iron oxide, bis(chloromethyl) ether, and others. Asbestos fiber types named: chrysotile, amosite and crocidolite.
• Main results:
  • Asbestos was listed in the report's table among the substances widely accepted as human pulmonary carcinogens.
  • The report noted that questions had arisen about the relative carcinogenicity of the different asbestos fiber types, and about the role of other factors such as cigarette smoking, trace metals and impurities in the fibers.
  • Quoting the International Agency for Research on Cancer: the risk of lung carcinoma and mesothelioma was small in workers in chrysotile mines and mills, and possibly the same for amosite.
  • Quoting the International Agency for Research on Cancer: some crocidolite mining areas and mills had been associated with a higher risk of mesothelioma.
  • Quoting the International Agency for Research on Cancer: in manufacturing and application industries, mesotheliomas had been caused by exposure to crocidolite, and less frequently to amosite and chrysotile.
  • Quoting the International Agency for Research on Cancer: the period between first exposure and development of tumors was long, usually more than 30 years.
  • Quoting the International Agency for Research on Cancer: mesotheliomas had occasionally been diagnosed among families of asbestos workers.
  • Quoting the International Agency for Research on Cancer: there was at that time no evidence that exposure of the general population to past levels of asbestos dust in air, beverages, drinking water, food or pharmaceutical preparations increased cancer risk.
  • Quoting the International Agency for Research on Cancer: cigarette smoking enhanced the risk of lung carcinoma in asbestos workers to a much greater degree than in the rest of the population.
• The authors' conclusion: The report concluded that it was impossible at that time to formulate a complete and authoritative list of all substances that can cause lung cancer. It stated that attention to the approach of the environmental epidemiologist was essential because prevention appeared to be the most promising approach (the final word is garbled in the scan).
• Limitations the authors state:
  • The report was based largely on epidemiologic evidence rather than experimental animal work.
  • Discrepancies among the authorities' lists were attributed partly to differing report dates and to differences in how complete each listing tried to be.
  • Some substances implicated as carcinogenic in humans had not yet been evaluated by the committee.

Topics

Medical terms in this study, explained in our Lexicon: Carcinogenic, Carcinoma, Mesothelioma, Chrysotile, Amosite, Crocidolite.

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