Asbestos--can it be used safely?

Our plain-English summary of Asbestos--can it be used safely?, by D. Gloag (British Medical Journal, 1981).

The study

• Author: D. Gloag
• Journal: British Medical Journal
• Published: 1981;282(6263):551-3
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004668).

Summary of the article

This article, part of a British Medical Journal series on pollution, asked whether asbestos could be used safely and whether there were health hazards at low levels of exposure. The author reviewed published epidemiological and case studies and official reports. She described the main asbestos types (crocidolite, amosite, anthophyllite and chrysotile), their uses, and the associated cancers. These were mainly lung cancer and pleural and peritoneal mesothelioma, with increases in gastrointestinal and laryngeal cancers reported in some studies. She outlined limitations of the evidence: latent periods of commonly 20-50 years, incomplete exposure histories, inappropriate control groups, and dust concentrations that were often impossible to estimate. Evidence on household and neighbourhood exposure was summarised. A cited study estimated the annual mesothelioma rate in Canada in 1972 at 2.8 per million in men and 0.7 in women. The review reported a generally accepted gradient of risk from chrysotile through amosite to crocidolite. For Quebec chrysotile miners and millers, the mesothelioma risk was perhaps three to six times that of the general population, compared with 100-200 times in insulation workers exposed to mixed fibres. Some data suggested that risk was proportional to cumulative dose. Citing an EEC report, the author noted suggestive but inadequate evidence for a threshold. She concluded that for chrysotile at low levels the epidemiological data were reassuring, because even without a threshold the risks must be exceedingly small.

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, by a staff editor of the British Medical Journal, reviewed published evidence. It did not report a new study. It asked whether asbestos can be used safely and whether there is a cancer threshold at low exposure. The author described a generally accepted gradient of risk for lung cancer and mesothelioma, from chrysotile through amosite to crocidolite. Among the studies summarised, over 11 000 chrysotile miners and millers in Quebec Province showed increased deaths from lung cancer and asbestosis only among those exposed to dust levels unacceptable by present standards, and only 11 pleural mesotheliomas occurred in 50 years. At a friction-materials factory that mainly used chrysotile, all but two of 10 pleural mesothelioma deaths had definite crocidolite exposure. The author noted several problems with the evidence. Mesotheliomas can take 20-50 years to appear, lifetime exposure histories and dust levels are hard to establish, and control groups are not always appropriate. The author concluded that for chrysotile at low levels the epidemiological data were reassuring, and that even without a threshold the risks must be exceedingly small.

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/commentary by a journal staff editor, part of a 'Pollution and People' series; no original data
• Who was studied: No participants studied directly; the article summarised published epidemiological and case studies of asbestos miners, millers, factory, textile, friction-materials and insulation workers, their relatives, and people living near mines and factories
• Exposure: Asbestos in general and by fibre type: crocidolite, amosite, anthophyllite (amphiboles) and chrysotile (serpentine); occupational, household and neighbourhood exposure
• Main results:
  • The author described a generally accepted gradient of risk for lung cancer and mesothelioma, from chrysotile through amosite to crocidolite
  • In a cited series of over 11 000 chrysotile miners and millers in Quebec Province, increased mortality, particularly from lung cancer and asbestosis, occurred only in those exposed to dust concentrations unacceptable by present standards; only 11 pleural mesotheliomas occurred in 50 years
  • A cited review by the same workers concluded that mesothelioma risk for those in chrysotile production was perhaps three to six times the general population, compared with 100-200 times for insulation workers exposed to chrysotile but also crocidolite or amosite
  • A cited American study of a factory processing almost exclusively chrysotile found a lung cancer standardised mortality ratio of 223 at the lowest cumulative doses; only one of 191 deaths was due to mesothelioma
  • At a cited friction-materials factory using mainly chrysotile, there were 10 deaths from pleural mesothelioma, and all but two of these cases had definitely been exposed to crocidolite
  • A cited London study found an excessive proportion of patients had lived within half a mile of a factory processing amphibole asbestos
  • For lung cancer in chrysotile miners and millers, cited Canadian results showed a linear dose-response relationship; mesotheliomas were too few for dose-response inferences
• The authors' conclusion: The author concluded that for chrysotile at low levels the epidemiological data are reassuring, and that even if there is no threshold, the diminishing probability of cancer induction must result in exceedingly small risks
• Limitations the authors state:
  • Mesotheliomas may have latent periods of 20-50 years, so some may be missed in follow-up studies
  • Full lifetime exposure histories are hard to obtain or to exclude, so associations may be missed or tumours wrongly attributed
  • Control groups in studies are not always appropriate
  • Dust concentrations to which patients were exposed are often difficult or impossible to estimate
  • Use of a single fibre type is rare in industry, which complicates comparisons between fibre types

Topics

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

Medical terms in this study, explained in our Lexicon: Crocidolite, Amosite, Anthophyllite, Chrysotile, Lung Cancer, Peritoneal Mesothelioma, Laryngeal Cancer, Mesothelioma.

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