Cancer in a factory using amosite asbestos

Our plain-English summary of Cancer in a factory using amosite asbestos, by E.D. Acheson, M.J. Gardner, P.D. Winter, et al (International Journal of Epidemiology, 1984).

The study

• Authors: E.D. Acheson, M.J. Gardner, P.D. Winter, C. Bennett
• Journal: International Journal of Epidemiology
• Published: 1984;13(1):3-10
• Cited by: 66 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. 000521).

Abstract

The paper describes the mortality experience of 5969 men employed in a factory where insulation board was manufactured using amosite asbestos from 1947 to 1979. 422 (7%) of the men were known to have died by the end of 1980. Among the 4820 men engaged in the manufacture of insulation board a doubling of the risk of lung cancer has occurred (57 deaths observed; 29 deaths expected). An excess is present both in men who entered the factory before and after 1960. Among the 2461 for whom smoking information is available a detectable excess risk is limited to current smokers exposed to higher levels of asbestos. Apart from five deaths from mesothelioma no statistically large or significant excesses of mortality from cancers of other sites have occurred, but further follow-up of the cohort is in progress. Nine deaths from asbestosis have been recorded. The results are discussed in the light of other studies of the effects of exposure to amosite asbestos.

In plain English

The authors followed 5969 men from an insulation board factory in Uxbridge, London, to the end of 1980, comparing deaths with national rates for England and Wales. The factory used amosite from 1947, with small amounts of chrysotile until 1973. By the end of 1980, 422 men (7%) had died. Among the 4820 asbestos product workers, 61 died of cancer of the lung and pleura (57 certified as lung cancer) against 29.1 expected (SMR 210; 95% confidence limits 160 to 269), in men starting both before and after 1960. Lung cancer deaths rose significantly with job dustiness, without a convincing trend by length of employment or time since first exposure. Five men died of mesothelioma (four pleural, one peritoneal), nine of asbestosis. No other cancer site showed a significant excess. Among 2461 men with smoking records, an excess was detected only in asbestos workers who were current or ex-smokers, with a substantial excess in the medium/heavy exposure group; power to detect a relative risk under sixfold in the few non-smokers was low. The authors called exposure ratings largely subjective, as no dust measurements existed before 1969.

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: Retrospective cohort (mortality) study comparing observed deaths with expected deaths calculated from national death rates for England and Wales (standardized mortality ratios, SMRs)
• Who was studied: 5969 men employed at the Cape Boards factory in Uxbridge, London, between 1945 and the end of 1978, followed for deaths to the end of 1980. 4820 made asbestos products; the other 1149 were brickworkers, office workers, canteen workers, cleaners and similar ('other workers').
• Exposure: Manufacture of insulation board using commercial amosite mixed with chrysotile (from nil to about 3% by weight) from 1947 to 1973, and amosite alone from 1973 until asbestos use ended by 1979. Crocidolite was used only in five short experimental trials in 1962 and 1964. An industrial hygienist rated jobs as heavy, medium, low, casual or background exposure.
• Main results:
  • Of all 5969 men, 422 (7%) had died by the end of 1980.
  • Asbestos workers had significant excesses of deaths from neoplasms (SMR 144; 95% CLs 119, 174) and from injury and poisoning (SMR 141; 95% CLs 104, 186). Of the 30 injury deaths in this group, 12 were suicides. The authors judged it unlikely that these deaths were related to overt asbestos-induced disease.
  • Among asbestos workers, the excess was virtually limited to cancer of the lung and pleura: 61 deaths against 29.1 expected, SMR 210 (95% CLs 160, 269). Of these deaths, 57 were certified as lung cancer and 4 as pleural mesothelioma.
  • Lung cancer mortality among asbestos workers was significantly raised both for those who entered in 1947 to 1959 (SMR 268; 95% CLs 178, 388) and for those who entered in 1960 to 1978 (SMR 177; 95% CLs 122, 249).
  • Lung cancer mortality showed statistically significant trends with increasing dustiness of the most dusty job held, for both entry periods.
  • The highest lung cancer SMR in any larger subgroup was in men who entered before 1960 and worked in the two dustiest job categories: 20 observed, 6.13 expected, SMR 326 (95% CLs 199, 504).
  • The authors found no convincing trends of increasing lung cancer mortality with duration of exposure or with time since first exposure, and they could not explain this. An analysis limited to lung cancer deaths after leaving the factory showed a slight rise in the SMR with increasing duration of exposure.
  • Five deaths were certified as mesothelioma (four pleural, one peritoneal), all among asbestos workers. These had been reported earlier.
  • Nine deaths were certified as asbestosis, for which the expected number is virtually zero. The excess of respiratory disease deaths overall was not statistically significant.
  • Among asbestos workers there was no large or significant excess of cancers of all other sites combined: 48 deaths observed against 45.3 expected.
  • No significant excesses of cancer were seen among the other workers.
  • Smoking information was available for 2461 men (41%). Among them, the excess lung cancer risk was limited to asbestos workers who were current or ex-smokers. No increased risk was demonstrable among the small number of non-smokers, but the study's power to detect a relative risk less than sixfold in that group was low.
  • Among smokers, the expected numbers would rise by about 30% if based on rates in smokers. The authors said this would still indicate a substantial excess of lung cancer among the medium/heavy exposure group.
  • The data were consistent with a greater than additive, but less than multiplicative, interaction between smoking and asbestos.
• The authors' conclusion: The authors concluded that, apart from the five mesothelioma deaths, the principal finding was a substantial excess of lung cancer deaths among men exposed principally to commercial amosite with a small quantity of chrysotile. The excess was present in men who entered both before and after 1960 and was related to the dustiness of their work.
• Limitations the authors state:
  • The exposure classification was largely subjective, because no dust measurements were available before 1969.
  • The comparison group of 'other workers' worked within the same factory perimeter and may also have been exposed to asbestos.
  • The cohort was relatively young, with over 40% of the men born after 1940.
  • For men who entered after the 1965 improvements in working conditions, the numbers were too small to support any reliable conclusion.
  • Smoking was recorded only from 1971 onward. The study had low power to detect a relative risk less than sixfold in non-smokers.
  • Expected lung cancer deaths were based on general population rates and were not corrected for smoking.
  • The authors cautioned against using their highest-subgroup SMR to compare working conditions with other factories, because worker selection differs widely between studies.

Topics

Medical terms in this study, explained in our Lexicon: Amosite, Lung Cancer, Mesothelioma.

Related studies

• Mortality from all cancers of asbestos factory workers in east London 1933-80 — G. Berry, M.L. Newhouse, et al. (2000)
• Mortality experience of residents in the neighborhood of an asbestos factory — E.C. Hammond, L. Garfinkel, et al. (1979)
• Fiber levels and disease in workers from a factory predominantly using amosite — A.R. Gibbs, M.J. Gardner, et al. (1994)
• Long term radiological effects of short term exposure to amosite asbestos among factory workers — R. Ehrlich, R. Lilis, et al. (1992)
• Mortality experience of amosite asbestos factory workers: dose-response relationships 5 to 40 years after onset of short-term work exposure — H. Seidman, I.J. Selikoff, et al. (1986)
• Dust exposure and mortality in an American factory using chrysotile, amosite, and crocidolite in mainly textile manufacture — A.D. McDonald, J.S. Fry, et al. (1983)

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