Patterns of mortality in asbestos factory workers in London

Our plain-English summary of Patterns of mortality in asbestos factory workers in London, by M.L. Newhouse, G. Berry (Annals of the New York Academy of Sciences, 1979).

The study

• Authors: M.L. Newhouse, G. Berry
• Journal: Annals of the New York Academy of Sciences
• Published: 1979;330:53-60
• Cited by: 54 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. 001040).

Summary of the article

The authors reported mortality among workers at an East London asbestos factory, open from 1913 to 1968, which made asbestos textiles and later insulation and other products using crocidolite (until the late 1950s), chrysotile and amosite. The cohorts were 4600 men who began work between 1933 and 1964 and 922 women first employed between 1936 and 1942. Vital status was traced through national registers, and follow-up ran to 31 December 1975. Jobs were graded as low-moderate or severe exposure, and laggers were analysed separately. Among men there were 775 deaths, including 46 from mesothelial tumours (19 pleural, 27 peritoneal) and 103 from lung carcinoma. Laggers had 25 deaths from cancers of the lung and pleura against 5.6 expected. Lung and pleural cancer SMRs generally rose with length of follow-up and with exposure. Among women, 77% were traced; 225 had died, including 13 pleural and 8 peritoneal mesothelial tumours. Severely exposed women with long employment had excess breast (6 observed, 2.1 expected) and ovarian (3 observed, 0.74 expected) cancer, which the authors interpreted cautiously. Mesothelioma death rates related clearly to the length and severity of exposure. A 1971 smoking survey suggested that smoking explained only a small part of the lung cancer excess. The results were consistent with asbestos and smoking combining multiplicatively. The authors concluded that, under past conditions, workers starting in their early twenties would have markedly diminished life expectancies.

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In plain English

This study followed deaths among workers at an East London asbestos factory. It used crocidolite until the late 1950s, plus chrysotile and amosite. It covered 4600 men starting work in 1933 to 1964 and 922 women first employed in 1936 to 1942, followed to the end of 1975. There were 775 male deaths. The authors analysed 545 of these, among non-laggers followed at least 10 years. That group included 46 mesothelial tumor deaths (19 pleural, 27 peritoneal) and, apart from pleural mesothelioma, 103 lung cancer deaths. Of the women, 225 had died, including 13 pleural and 8 peritoneal mesothelial tumors. In both sexes, mesothelioma death rates were related to length and severity of exposure. Severely exposed, long-employed women had statistically significant excesses of breast and ovarian cancer, but the authors cautioned against much reliance on these figures. A 1971 survey of selected male and all surviving female workers found that a greater proportion smoked or had smoked than in the general population. The authors judged this a small bias in the lung cancer excess. They concluded that, under past conditions, workers starting in their early twenties would have markedly diminished life expectancies.

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: Mortality (cohort) study of workers at one asbestos factory, continuing earlier reports, with an added survey of smoking habits
• Who was studied: 4600 men who began work between April 1, 1933 and March 31, 1964, and 922 women first employed between January 1, 1936 and December 31, 1942, at an East London asbestos factory; followed to December 31, 1975
• Exposure: Work at a factory making asbestos textiles, insulation materials (particularly asbestos pipe sections) and other products, using crocidolite until the late 1950s and also chrysotile and amosite. Jobs were grouped as low-moderate or severe exposure, with laggers analysed separately. Before 1945, most production jobs were estimated to average 20 fibers/ml or higher, and low-moderate jobs probably 5-10 fibers/ml.
• Main results:
  • There were 775 deaths among the male workers.
  • The main male analysis covered 545 deaths among workers other than laggers who had been followed for 10 years or longer.
  • In that analysed group of male non-laggers, there were 46 deaths from mesothelial tumors: 19 pleural and 27 peritoneal.
  • In the same group, apart from pleural mesothelioma, there were 103 deaths from lung cancer. The authors describe lung cancer as the most common tumor of asbestos workers.
  • Among the men, asbestosis was given as the cause of death in 13 instances.
  • The laggers (1368 males) were analysed separately. Their mortality so far was not dissimilar from that of other severely exposed male workers.
  • Among the men, the standardized mortality ratio (SMR) for cancers of the lung and pleura generally rose with longer follow-up and with increasing exposure.
  • In job categories 1 and 2 (ground workers, canteen workers, and production workers with very little and short dust exposure), the SMR for cancers of the lung and pleura was 176, and there were three deaths from mesothelial tumors.
  • Mesothelioma death rates showed a very definite relationship to length and severity of exposure.
  • By December 31, 1975, 225 of the women had died.
  • Among the women there were 13 pleural and 8 peritoneal mesothelial tumors, about 10% of all deaths, a similar proportion to the men.
  • Severely exposed women with long exposures had a greater excess of lung cancer than men with similar exposure.
  • In severely exposed women with long employment, there were statistically significant excesses of breast cancer (6 observed vs 2.1 expected, p less than 0.05) and ovarian cancer (3 observed vs 0.74 expected, p less than 0.05).
  • A smoking survey of a selected group of male factory workers and all surviving female workers was made between April and August 1971.
  • In that survey, a greater proportion of both men and women smoked or had smoked than in the general population of England and Wales. Among men, 74% smoked compared with 66% expected.
  • The authors estimated that smoking accounted for only a small part of the lung cancer excess, a bias represented by factors of 1.1 for men and 1.2 for women.
  • In the prospective smoking survey, the authors found the results consistent with their earlier finding that asbestos and smoking appear to combine multiplicatively in producing lung cancer.
  • At 35 years after first exposure, observed survival was about 7% below expected for men and about 10% below expected for women.
• The authors' conclusion: The authors concluded that, under conditions that prevailed in the past, men and women who started work in their early twenties would have markedly diminished life expectancies.
• Limitations the authors state:
  • Laggers may have had previous exposure with other employers, so their durations of exposure are not certain.
  • Women were harder to trace because of name changes at marriage; the vital status of only 77% was ascertained in 1971.
  • The breast and ovarian cancer findings come from one comparatively small cohort of women, and factors related to marital status and parity may be important.
  • There were insufficient data for a more detailed analysis of smoking, and firm conclusions must await more data.
  • Only 20% of the workers had been followed for 30 years or longer, and the authors expect deaths from mesothelial tumors to continue to rise for some time.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Textiles, Crocidolite, Chrysotile, Amosite, Insulator, Carcinoma, Pleura, Mesothelioma.

Related studies

• Mortality of factory workers in east London 1933-80 — M.L. Newhouse, G. Berry, et al. (1985)
• Mortality from all cancers of asbestos factory workers in east London 1933-80 — G. Berry, M.L. Newhouse, et al. (2000)
• Correlation between fibre content of the lung and disease in east London asbestos factory workers — J.C. Wagner, M.L. Newhouse, et al. (1988)
• Combined effect of asbestos and smoking on mortality from lung cancer and mesothelioma in factory workers — G. Berry, M.L. Newhouse, et al. (1985)
• Correlation between fibre content of lung and disease in east London asbestos factory workers — R.M. Rudd (1989)
• Combined effect of asbestos exposure and smoking on mortality from lung cancer in factory workers — G. Berry, M.L. Newhouse, et al. (1972)

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