Mortality of two groups of women who manufactured gas masks from chrysotile and crocidolite asbestos: a 40-year follow-up

Our plain-English summary of Mortality of two groups of women who manufactured gas masks from chrysotile and crocidolite asbestos: a 40-year follow-up, by E.D. Acheson, M.J. Gardner, E.C. Pippard, et al (British Journal of Industrial Medicine, 1982).

The study

• Authors: E.D. Acheson, M.J. Gardner, E.C. Pippard, L.P. Grime
• Journal: British Journal of Industrial Medicine
• Published: 1982;39(4):344-8
• Cited by: 120 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. 000653).

Abstract

ABSTRACT Two groups of women were exposed to asbestos while manufacturing gas masks in Lancashire before and during the second world war. One group (in Blackburn) is believed to have been concerned almost exclusively with the manufacture of civilian respirators (containing chrysotile) while the other (in Leyland) made respirators for the armed Forces (containing crocidolite) and a much smaller number of civilian respirators. Excess mortality ascribed to lung cancer and ovarian cancer were found at the second factory (statistically significant at the 1% level) but not at the first. Mesothelioma was mentioned on the death certificates of five women who had worked in Leyland and one woman in Blackburn.

In plain English

This study tracked deaths among women who were making gas masks in Lancashire in September 1939. One group, 570 women in Blackburn, made civilian masks containing chrysotile. The other, 757 women from Leyland and Preston, mainly made armed Forces masks and had been exposed to crocidolite as well as some chrysotile. Deaths from 1951 to 30 June 1980 were compared with the numbers expected from rates for England and Wales. In the Leyland group there were 15 deaths from lung and pleura cancer (two of them pleural mesothelioma) against 6.2 expected, and 12 ovarian cancer deaths against 4.4 expected. Both excesses were statistically significant. The Blackburn group showed no significant excess of these cancers but had extra deaths from acute myocardial infarction (heart attack). Mesothelioma appeared on the death certificates of five Leyland women and one Blackburn woman. The authors concluded that the pattern was consistent with mesothelioma, and possibly ovarian cancer, being particularly associated with crocidolite. They noted possible unknown differences in dose and duration of exposure, and that some ovarian cancer deaths might have been peritoneal mesothelioma.

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: Historical cohort mortality study comparing observed deaths with numbers expected from England and Wales rates, with an adjustment for local area mortality
• Who was studied: Women identified through the National Health Service Central Register as working in gas mask manufacture in September 1939: 570 women resident in Blackburn and 757 women resident in Leyland (435) and Preston (322), followed from 1 January 1951 to 30 June 1980. Men (95 at Leyland, 58 at Blackburn) were excluded from the main analysis.
• Exposure: Blackburn women made civilian gas masks containing chrysotile (with charcoal and merino wool, no crocidolite). Leyland women mainly made armed Forces (Service) gas masks containing crocidolite and also had some exposure to chrysotile.
• Main results:
  • Both groups had a statistically significant excess of deaths from all causes compared with England and Wales rates. Leyland had 219 deaths observed against 185 expected (SMR 118, 95% limits 103 to 135, p less than 0.05). Blackburn had 177 observed against 128 expected (SMR 138, 95% limits 119 to 160, p less than 0.01).
  • In Blackburn, the excess of deaths from causes other than cancer was due to deaths from acute myocardial infarction.
  • Leyland women had 15 deaths from cancer of the lung and pleura, 2 of them pleural mesothelioma, against 6.2 expected (SMR 241, 95% limits 135 to 397, p less than 0.01). The ratio to the local area SMR was 2.25 (p less than 0.01). Blackburn women had 7 such deaths, 1 of them pleural mesothelioma, against 4.8 expected (SMR 145, 95% limits 58 to 298), which was not statistically significant.
  • With the two Leyland deaths from pleural mesothelioma excluded, an excess of lung cancer deaths remained in Leyland that was statistically significant at the 5% level.
  • Leyland women had 12 deaths from cancer of the ovary against 4.4 expected (SMR 275, 95% limits 142 to 481, p less than 0.01). The ratio to the local area SMR was 2.96 (p less than 0.01). The Blackburn ovarian cancer result (SMR 148, 95% limits 48 to 344) was not statistically significant.
  • Mesothelioma was mentioned on the death certificates of five Leyland women (three pleural, two peritoneal) and one Blackburn woman (pleural). Four were certified as the underlying cause of death, against 0.2 expected at England and Wales rates. Two Leyland women's deaths were certified as due to asbestosis, and one man at Leyland died of pleural mesothelioma.
  • In Leyland women, observed deaths from lung and ovarian cancer rose faster over time than expected, so the excess kept growing up to 40 years after gas mask work. This was particularly pronounced for ovarian cancer.
• The authors' conclusion: The authors concluded that the differences between Leyland and Blackburn probably lay in the different exposures in the two factories. They judged the pattern of deaths consistent with the view that mesothelioma (and possibly ovarian cancer) is particularly associated with exposure to crocidolite.
• Limitations the authors state:
  • Besides the different fiber types, there may have been unknown differences in dose and duration of exposure between the two factories.
  • Nothing was known of the women's industrial history before and after 1939.
  • Deaths attributed to ovarian cancer may have been misclassified and may actually have been peritoneal mesothelioma, which is hard to tell apart from ovarian cancer.
  • Local area mortality rates were available only for 1968-78, not the whole 1951-80 study period.
  • The authors believed the Blackburn woman with pleural mesothelioma had transferred to a second Blackburn factory that made Service respirators containing crocidolite.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Chrysotile, Crocidolite, Lung cancer, Ovarian cancer.

Medical terms in this study, explained in our Lexicon: Chrysotile, Crocidolite, Respirator, Lung Cancer, Ovarian Cancer, Mesothelioma, Death Certificate.

Related studies

• Sixty years on: the price of assembling military gas masks in 1940 — J.C. McDonald, J.M. Harris, et al. (2006)
• Mesothelioma after crocidolite exposure during gas mask manufacture — A.D. McDonald, J.C. McDonald (1978)
• Malignant mesotheliomas in former miners and millers of crocidolite at Wittenoom (Western Australia) after more than 50 years follow-up — G. Berry, A. Reid, et al. (2012)
• Follow-up study of chrysotile asbestos textile workers: cohort mortality and case-control analyses — J.M. Dement, D.P. Brown, et al. (1994)
• Lung fiber burden in the Nottingham gas mask cohort — G. Berry, F. Pooley, et al. (2009)
• 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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