Cancer and asbestos

Our plain-English summary of Cancer and asbestos (British Medical Journal, 1968).

The study

• Journal: British Medical Journal
• Published: 1968;3(5616):448-9
• Read it: PubMed · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001439).

In plain English

This unsigned British Medical Journal editorial was not a new study. It reviewed reports from the 1965 New York and 1968 Dresden asbestos conferences and other work. It said asbestos workers were known by 1965 to be at special risk of bronchial carcinoma and mesothelioma, possibly linked particularly to crocidolite. Citing W. D. Buchanan, it said the percentage of men with asbestosis also developing lung cancer or mesothelioma rose from 19.7 to 54.5. It said a gastrointestinal cancer risk had no real corroboration yet. It described hamster experiments where chrysotile plus benzpyrene produced lung carcinomas but chrysotile alone did not. It cited Selikoff and colleagues' conclusion that asbestos-exposed smokers had eight times the bronchial carcinoma death risk of smokers in other jobs. It reported S. A. Roach's calculation that chrysotile exposure up to 100 fibre-years carried under 1% risk of clinical signs of asbestosis. It said it was unknown whether this applied to amosite and crocidolite, or whether the standard was acceptable given mesothelioma and lung cancer risk. The editorial concluded that people must learn to live safely with asbestos.

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: Unsigned editorial (leading article) reviewing findings presented at international conferences and in published studies; not an original study
• Who was studied: No study population of its own. The editorial discussed reports on asbestos workers, men with asbestosis, cigarette smokers exposed to asbestos at work, naval dockyard workers at Devonport, and laboratory hamsters. These reports came from the 1965 New York and 1968 Dresden conferences and other publications.
• Exposure: Occupational asbestos dust, including crocidolite, amosite and chrysotile (UK workers were often exposed to all three); in animal work, chrysotile asbestos with 3,4-benzpyrene; cigarette smoking combined with occupational asbestos exposure; chrysotile exposure measured in fibre-years
• Main results:
  • By the 1965 conference, asbestos workers were known to be at special risk of at least two cancers: bronchial carcinoma and mesothelioma
  • The epidemiological data available in 1965 suggested the risk may be associated particularly with crocidolite. It was uncertain whether amosite and chrysotile were similarly hazardous.
  • According to W. D. Buchanan, in males the average age at death from asbestosis rose from 49.3 years in an earlier period to 60.4 years during 1961-3 (the earlier dates are garbled in the scanned text)
  • According to Buchanan, over the same period the percentage of men with asbestosis who also developed lung cancer or mesothelioma rose from 19.7 to 54.5
  • There had so far been no real corroboration that asbestos exposure increases the risk of gastrointestinal cancer
  • Asbestos bodies had been detected in the sputum of about 50% of males in certain industrial cities. The editorial said this means mere detection of asbestos in the lungs is not necessarily a prelude to lung cancer or mesothelioma.
  • W. E. Smith and colleagues reported pulmonary carcinomas in hamsters given a mixture of chrysotile asbestos and 3,4-benzpyrene into the trachea. Asbestos alone had no neoplastic effect, and benzpyrene alone induced only tracheal and bronchial papillomas.
  • Selikoff and colleagues concluded that cigarette smokers occupationally exposed to asbestos had eight times the risk of dying of bronchial carcinoma as cigarette smokers in other occupations. The editorial said this suggests asbestos dust and cigarette smoke act synergically.
  • P. G. Harries described measures at the Devonport naval dockyards to reduce unnecessary asbestos exposure, including alternative materials and protective clothing
  • According to calculations by S. A. Roach, the risk of clinical signs of asbestosis is less than 1% if chrysotile fibres per c.cm. multiplied by years of exposure does not exceed 100 fibre-years
• The authors' conclusion: The editorial concluded that people must learn to live safely with asbestos, although the mechanism of asbestos carcinogenesis remained an enigma. It hoped that shipyards would follow the Devonport measures, and that hygiene standards based on working-lifetime exposure would be seriously considered.
• Limitations the authors state:
  • Fibrous materials other than asbestos may form structures very similar to asbestos bodies, a possible problem for all studies
  • It was unknown whether the 100 fibre-year calculation for asbestosis from chrysotile applies to amosite and crocidolite
  • It was also unknown whether this exposure standard is an acceptable compromise in relation to the risk of mesothelioma and lung cancer

Topics

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

Related studies

• Tests for effect of asbestos on benzo[a]pyrene carcinogenesis in the respiratory tract — L. Miller, W.E. Smith, et al. (1965)
• Asbestos levels in human lungs — C. Gold (1969)
• Mortality in the chrysotile asbestos mines and mills of Quebec — J.C. McDonald, A.D. McDonald, et al. (1971)
• Unsuspected exposure to asbestos and bronchogenic carcinoma — K.M. Martischnig, D.J. Newell, et al. (1977)
• The relationship between asbestosis and bronchial cancer — G.K. Sluis-Cremer (1980)
• Cohort analysis of changes in incidence of bronchial carcinoma in a textile asbestos factory — J.F. Knox, R.S. Doll, et al. (1965)

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