Epidemiology of asbestos cancers

Our plain-English summary of Epidemiology of asbestos cancers, by J.C. Wagner, J.C. Gilson, G. Berry, et al (British Medical Bulletin, 1971).

The study

• Authors: J.C. Wagner, J.C. Gilson, G. Berry, V. Timbrell
• Journal: British Medical Bulletin
• Published: 1971;27(1):71-6
• Type of article: Review
• Cited by: 71 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. 001379).

Summary of the article

This review from the Medical Research Council's Pneumoconiosis Unit summarized the history, types and uses of asbestos and the epidemiological evidence on asbestos-related cancers from Southern Africa, Britain, the USA, Canada, Finland, Sweden, Holland and other countries. Early evidence included Doll's 1955 study, in which men employed before 1930 in an asbestos textile factory had a lung cancer death-rate ten times the expected rate. It also included more than 100 mesothelioma cases reported in north-west Cape Province, mainly in people working or living near the crocidolite mines. The British mesothelioma register held 622 cases by 1969, with about 60 new cases detected each year. New York insulation workers had lung cancer death-rates about seven times those expected, and the risk was exceptionally high in those also exposed to cigarette smoke. Among about 12000 Quebec chrysotile miners and millers, the lung cancer death-rate in the most exposed group was about five times that in the least exposed. The authors concluded that bronchial cancer risk was related to the intensity of past exposure and to the risk of asbestosis. Mesothelioma was less certainly dose related and varied more with fibre type: anthophyllite very rarely, if ever, caused it, chrysotile alone was probably a rare cause, and crocidolite was rated higher in risk than amosite. They discussed prevention through substitution, safer fibre types, dust control, personal protection and threshold-limit values.

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 1971 article from the Medical Research Council's Pneumoconiosis Unit was a review, not a new study. It reviewed epidemiological studies of asbestos-related cancers from Southern Africa, Britain, the USA, Canada, Finland, Sweden, Holland and elsewhere. It reported that the unit's British mesothelioma register held a cumulative 622 cases by 1969, with about 60 new cases detected each year, concentrated in ports and asbestos-factory cities. Cited reports described more than 100 mesotheliomas near crocidolite mines in north-west Cape Province, very few in the Transvaal amosite area, and none linked to anthophyllite in Finland. The authors concluded that the link between past asbestos exposure and bronchial (lung) cancer and mesothelioma of the pleura and peritoneum was well established. They judged lung cancer risk to be related to exposure intensity and exceptionally high with cigarette smoking. They judged that mesothelioma risk appeared to vary by fibre type, with crocidolite rated above amosite and chrysotile alone "probably a rare cause". They noted that past dust levels were poorly known and that industrial workers were usually exposed to more than one fibre type.

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 of epidemiological studies of asbestos-related cancers, with a brief history and description of asbestos types and uses
• Who was studied: Published and ongoing studies of asbestos miners, factory workers, insulation workers, dockyard and shipyard workers, and mesothelioma case series from Southern Africa (Cape Province, Transvaal, Rhodesia, Swaziland), Britain, the USA, Canada (Quebec), Finland, Sweden, Holland, Australia and other countries. The review also covered the Pneumoconiosis Unit's British mesothelioma register, kept since 1962.
• Exposure: Chrysotile and the amphiboles crocidolite, amosite and anthophyllite, through mining and milling, textile manufacture, insulation, shipbuilding and dockyard work, and exposure outside the workplace
• Main results:
  • British mesothelioma register (Pneumoconiosis Unit): cumulative cases numbered 4 up to 1962, 160 to 1965 and 622 to 1969, with about 60 new cases now detected each year
  • Register cases in Britain were concentrated in ports and in cities with factories that had handled large amounts of asbestos
  • North-west Cape Province, a crocidolite mining area (cited study by Gilson, 1966): more than 100 cases of pleural and peritoneal mesothelioma had been reported, mainly in people working or living near the mines
  • Transvaal, where amosite and small amounts of crocidolite were mined (cited study): mesotheliomas were very rare
  • Finland, anthophyllite: no mesotheliomas associated with anthophyllite exposure had been detected
  • Quebec chrysotile miners and millers (cited study by McDonald et al., about 12000 workers): the 10% of employees with the highest past dust exposure had an excess death rate from all causes of about 12%
  • Same Quebec study: the lung cancer death rate in the highest-exposed group was about five times that of the least-exposed employees
  • Canada as a whole: only 165 mesothelioma cases were recorded by over 400 pathologists between 1960 and 1968
  • New York insulation workers (cited study by Selikoff, Hammond & Churg): lung cancer death rates among those on the union books in 1942 were about seven times those expected
  • British factory making textiles and insulation with chrysotile, amosite and crocidolite (cited study by Newhouse, 1969): the excess bronchial cancer risk was almost as large after short (under two years) intensive exposure as after longer intensive exposure
  • British mesothelioma studies: in about 10-15% of cases with apparently complete information, no history of asbestos exposure had been recorded
  • The authors' assessment: the risk of bronchial cancer was more clearly related to the intensity of past exposure and to the risk of asbestosis
  • The authors' assessment: the risk of bronchial cancer was exceptionally high after exposure to both asbestos and cigarette smoke
  • The authors' assessment of mesothelioma by fibre type: anthophyllite very rarely, if ever, causes it, and chrysotile alone is probably a rare cause
  • The authors' assessment: present opinion rated the mesothelioma risk from crocidolite higher than that from amosite
• The authors' conclusion: The authors concluded that the association between past asbestos exposure and both bronchial cancer and mesothelioma of the pleura and peritoneum was well established from observations in many countries. They added that the two tumour types differ in their epidemiology.
• Limitations the authors state:
  • Information on past dust concentrations was scanty or largely guesswork, and populations at risk often could not be well defined
  • In industrialized countries, exposures had usually been to more than one fibre type
  • The long interval between first exposure and mesothelioma had so far prevented an estimate of what proportion of an exposed group develops the tumour
  • The evidence was not precise enough to express the relative cancer risk of different fibre types in numbers
  • It was not known whether the type of asbestos affects bronchial cancer risk in humans

Topics

Medical terms in this study, explained in our Lexicon: Epidemiology, Pneumoconiosis, Lung Cancer, Mesothelioma, Cape Province, Crocidolite, Insulator, Quebec Chrysotile.

Related studies

• Epidemiology of primary malignant mesothelial tumors in Canada — A.D. McDonald, A. Harper, et al. (1970)
• Environmental epidemiology. 3. Community effects of nonoccupational environmental asbestos exposure — I.J. Selikoff, E.C. Hammond (1968)
• Epidemiology of malignant mesothelioma--an outline — J.C. McDonald (2010)
• Epidemiology of diffuse mesothelial tumors: evidence of an association from studies in South Africa and the United Kingdom — J.C. Wagner (1965)
• Epidemiology of ovarian cancer: a review — B.M. Reid, J.B. Permuth, et al. (2017)
• Epidemiology of lung cancer — K.C. Thandra, A. Barsouk, et al. (2021)

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