The Consequences Of Exposure To Asbestos Dust In A Wartime Gas-Mask Factory

Our plain-English summary of The Consequences Of Exposure To Asbestos Dust In A Wartime Gas-Mask Factory, by J.S.P. Jones, F.D. Pooley, G.W. Sawle, et al (1980).

The study

• Authors: J.S.P. Jones, F.D. Pooley, G.W. Sawle, R.J. Madeley, P.G. Smith, G. Berry, B.K. Wignall, A. Aggarwal
• Published: Biological Effects Of Mineral Fibres (J.C. Wagner, Editor), Lyon: Iarc Scientific Publications, Volume 30, Pp. 637-653 (1980)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library, J-M no. 000817. The article is still under copyright, so we describe it here rather than post it.

In plain English

The authors traced wartime workers at a Nottingham factory assembling gas-mask filters. 'Military' filters, assembled for four-and-a-half years from September 1940, contained crocidolite; 'civilian' filters, made briefly from December 1939, contained chrysotile. Using a surviving wages book and medical records, they traced 578 of 951 women gas-mask workers; by the end of 1978, 166 had died, 74 of malignant disease. The women had 17 mesotheliomas and 12 bronchial carcinomas; 6.3 bronchial carcinomas were expected for all 951 women from national death rates. Other cancers were not in excess. By the end of 1978, 29 mesothelioma deaths were recorded among all factory workers. All mesotheliomas in women exposed to crocidolite followed more than five months' exposure, and mesothelioma rose significantly with length of exposure. Lung tissue came from 22 autopsies, 18 of them gas-mask workers. Those workers' crocidolite counts were almost all above those of controls from a 1976 UK survey, with no constant link between fibre count and exposure length. The authors drew no conclusions about chrysotile, as exposure was brief; 373 women were not traced.

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 study of a factory workforce, traced from a wartime wages book and hospital and general practitioner records, combined with mineral fibre analysis of lung tissue from 22 autopsies
• Who was studied: Wartime workers at a Nottingham factory that assembled gas-mask filter units. The main contract workforce totalled 900 or more, mainly women. The wages book listed 1,088 gas-mask workers (57 male, 951 female, 80 sex unknown). Analysis was confined to the 951 women, of whom 578 were traced. Follow-up ran to the end of 1978.
• Exposure: Assembly of 'military' gas-mask filter units containing crocidolite (pads of merino wool and 20% crocidolite), from September 1940 for four-and-a-half years. A smaller group of about 200 workers assembled 'civilian' filter units containing chrysotile for a short period from December 1939. Fibre type was deduced from the dates of employment. Duration of exposure came from the wages book.
• Main results:
  • Up to the end of 1978, 29 deaths from mesothelioma were recorded among people who had worked in the factory, and four more occurred in 1979.
  • Of the 29 mesotheliomas, 22 were pleural and 7 peritoneal. Among women gas-mask workers in the wages book there were 13 pleural and 4 peritoneal mesotheliomas, and 1 peritoneal mesothelioma in a man. Five pleural cases were in non-gas-mask workers in the factory.
  • Of the 578 traced women, 166 had died by the end of 1978, 74 of them of malignant disease.
  • In women workers, 12 bronchial carcinomas were observed against 6.3 expected. The expected numbers were calculated for all 951 women from national death rates. Mesothelioma was 17 observed, with no expected figure given.
  • In women workers, gastrointestinal carcinoma was 10 observed against 20.3 expected, and all cancers 74 observed against 66.0 expected.
  • Of 727 women exposed to crocidolite only, 139 had died and 16 had mesothelioma.
  • Of 102 women exposed to chrysotile, 10 had died, with no mesothelioma and no bronchial carcinoma.
  • All mesotheliomas in women exposed to crocidolite occurred after more than five months' exposure.
  • In women exposed to crocidolite only, the dose-response relationship for mesothelioma was reported as significant and consistent with a linear relationship with length of exposure.
  • For bronchial carcinoma in women exposed to crocidolite only, the dose-response relationship was reported with P less than 0.06, judged against the 5% significance level.
  • In the longest-exposure group of crocidolite-only women (51 women), 5 had mesothelioma (9.8%) and 2 had bronchial carcinoma (3.9%).
  • Lung tissue came from 22 autopsies: 18 gas-mask filter workers and 4 people who worked elsewhere in the factory. The mesothelioma patient with the longest crocidolite exposure had the highest crocidolite count (1,120,000 fibres per mg). Overall there was no constant relationship between fibre count and length of exposure.
  • Among patients exposed to chrysotile, one with three months' exposure had the highest chrysotile count (996,000 fibres per mg).
  • Compared with the 1976 United Kingdom mesothelioma survey, the gas-mask workers' crocidolite counts were almost all above the levels of the control group. Their chrysotile levels were mostly within the range of the controls.
  • One patient exposed exclusively to chrysotile had an intra-abdominal tumour that could have been either a mesothelioma or a malignancy from an ovarian carcinoma. No histology was available for this case.
• The authors' conclusion: The authors concluded that among those who worked with crocidolite there was a considerable excess of mesothelioma, a more modest excess of bronchial carcinoma, and no excess of other malignant disease. They stated that a dose-response relationship was established. They concluded that no conclusions could be drawn for the small number exposed to chrysotile for at most five months. They also considered that duration of exposure was not the crucial factor in lung dust retention or mesothelioma liability, and that fibre properties and dust-cloud size were probably more relevant.
• Limitations the authors state:
  • Most records were destroyed by bombing in 1941 or later, and an unknown number of names are missing from the wages book.
  • 373 women were not traced, so lung cancers among them are unknown.
  • The tracing method made it more likely to identify women who had died, and especially those with malignant disease. The size of this bias is unknown, though the authors state it does not invalidate their conclusions.
  • Chrysotile exposure was too short to allow comparison between the two fibre types.
  • Some lung tissue was taken at autopsy before a standardized sampling method existed, a possible source of inconsistency in fibre counts.
  • There was not enough detailed information to distinguish individual workers' exposure patterns.
  • There were too few cancer cases to analyse men, so analysis was confined to women.

Topics

Medical terms in this study, explained in our Lexicon: Crocidolite, Chrysotile, Mesothelioma, Carcinoma.

Browse return to medical research.