Current opinions on the asbestos cancer problem

Our plain-English summary of Current opinions on the asbestos cancer problem, by J.C. Wagner (The Annals of Occupational Hygiene, 1972).

The study

• Author: J.C. Wagner
• Journal: The Annals of Occupational Hygiene
• Published: 1972;15(1):61-5
• Cited by: 5 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. 001353).

Summary of the article

This article was a synopsis of a recent review of epidemiological studies and a general summary by the same author, drawing on opinions expressed at the 1969 Pneumoconiosis Conference in Johannesburg. The author described international studies sponsored by the International Union Against Cancer and the International Agency for Research on Cancer. A large survey of Quebec chrysotile miners showed a slight excess of lung cancer in the most heavily exposed group and no recorded mesotheliomas. Similar findings were reported for the Urals, Rhodesia, Italy and Finnish anthophyllite miners, and no mesotheliomas were observed in the Transvaal amosite areas. This contrasted with the North West Cape crocidolite fields. Lung cancer death rates among New York insulation workers were seven times those expected. Mesotheliomas were reported from shipbuilding ports where crocidolite had been used. In animal experiments, intrapleural chrysotile induced tumours as readily as crocidolite. The author discussed physical studies of fibre deposition. In rats exposed by inhalation, amphibole retention was six times that of chrysotile. North West Cape and Australian crocidolite fibres were thinner and shorter than Transvaal fibres. The author concluded that excessive exposure to all fibre types could cause lung cancer and that present evidence tended to implicate crocidolite in mesothelioma. He advised that crocidolite use should be restricted except where essential and that amosite required a high standard of dust control. He considered that chrysotile may carry only a small risk under practical dust control.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This article was a short review, a synopsis of two earlier articles on asbestos and cancer. It reported no new study of its own but described other researchers' findings. A survey of Quebec asbestos miners showed a slight excess of lung cancer in the most heavily exposed group, and no mesotheliomas were recorded among the miners. Lung cancer death rates in New York insulation workers were seven times those expected. Rats exposed to asbestos dust by inhalation retained six times more amphibole fibres than chrysotile. The article explained this by curly chrysotile fibres being caught in the airways more readily than straight amphibole fibres. The author also wrote that mesotheliomas could occur after relatively brief, though not necessarily light, exposures, and that there did not seem to be any clear dose-response pattern. The author concluded that present evidence tended to implicate crocidolite in mesothelioma and that its use should be restricted except where essential. In the author's view amosite's position was not yet clear, chrysotile may carry only a small risk with practical dust control, and further studies were urgently needed.

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 (synopsis of two earlier articles summarizing epidemiological and experimental studies by others)
• Who was studied: No study population of its own. The article summarized studies of asbestos miners (Quebec, the Urals near Sverdlovsk, Rhodesia, Italy, Finland, the Transvaal, the North West Cape), New York insulation workers, shipbuilding workers, and animal experiments.
• Exposure: Chrysotile, crocidolite, amosite and anthophyllite, from mining, milling, insulation work and shipbuilding
• Main results:
  • Reported from another study (McDonald et al., 1971): Quebec asbestos miners showed a slight excess of lung cancer in the most heavily exposed group.
  • Reported from another study (McDonald et al., 1971): no mesotheliomas were recorded among the Quebec mining population.
  • Reported from another study (Selikoff et al., 1970): lung cancer death rates in New York insulation workers were seven times those expected. This was particularly prevalent among heavy cigarette smokers. There was no correlation between smoking and mesothelioma.
  • Reported from other studies (Timbrell et al., 1970; Timbrell, 1970b): in rats exposed by inhalation to dust from the UICC reference samples, retention of amphiboles was six times greater than for chrysotile.
  • Reported from another study (Wagner and Berry, 1969): in animal experiments, intrapleurally inoculated chrysotile induced tumours as readily as crocidolite.
  • Reported from another study (Timbrell et al., 1971): crocidolite from the N.W. Cape and Australia was much thinner and shorter than Transvaal crocidolite and amosite. This could account for the high rate of pleural mesotheliomas in the N.W. Cape compared with only one possible case in the Transvaal.
  • The author's statement: mesotheliomas can occur after relatively brief, though not necessarily light, exposures, and there does not seem to be any clear dose-response pattern.
• The authors' conclusion: The author concluded that present evidence tended to implicate crocidolite in mesothelioma and that its use should be restricted except where essential. Amosite's position was not yet clear and needed a high standard of dust control. Chrysotile may carry only a small risk with practical dust control. Further studies were urgently needed.
• Limitations the authors state:
  • Pure exposures to a single type of fibre are extremely unusual in manufacturing countries.
  • Information about the type of asbestos used in the past by the New York insulation workers is incomplete.
  • There is no evidence yet implicating a particular asbestos type in lung cancer, and no way of measuring the relative risks of different fibre types.
  • Quantitative studies of how different fibre types are distributed in the lungs after inhalation need further development.

Topics

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

Medical terms in this study, explained in our Lexicon: Pneumoconiosis, Quebec Chrysotile, Lung Cancer, Mesothelioma, Anthophyllite, Transvaal, Amosite, Crocidolite.

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