Mortality Experience of the Retired Population of the Johns-Manville Corporation

Our plain-English summary of Mortality Experience of the Retired Population of the Johns-Manville Corporation, by P.E. Enterline, P. Decoufle, V. Smith, et al.

The study

• Authors: P.E. Enterline, P. Decoufle, V. Smith, C. Hollingsworth
• Published: Johns-Manville Corporation
• Type of article: Report
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This report looked at deaths among retired employees of the Johns-Manville Corporation. The company supplied data on 3075 retirees who retired between July 1, 1941 and December 31, 1966, and deaths were followed through December 31, 1967. The analysis covered the 2313 men who reached age 65; women were left out because their numbers were small. The men's death rates were compared with those of all U.S. men. Retirees were grouped by operation: asbestos products plants, the Quebec operations (where exposure was thought to be limited to chrysotile), non-asbestos products plants, the Sales Division and headquarters. Retirees from asbestos operations had excess deaths, mainly from cancer and respiratory disease, with the largest excess in respiratory cancer. Respiratory cancer was also high among retirees from non-asbestos production plants. A dust exposure score was related to excess deaths from all causes, but less clearly to cancer and respiratory disease taken separately. The authors concluded that their results were similar to an earlier study of working asbestos products employees. They noted that the U.S. comparison was probably slightly biased and that dust estimates for early periods were rough.

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 mortality study of a cohort of company retirees, comparing observed deaths with those expected from U.S. male death rates (standardized mortality ratios)
• Who was studied: 3075 Johns-Manville retirees who retired from July 1, 1941 through December 31, 1966. The analysis covered the 2313 male retirees who reached age 65, with deaths followed through December 31, 1967. Females were not analyzed because of small numbers. Groupings: asbestos products plants (11 locations outside Quebec), mining, milling and asbestos products at Asbestos, Quebec, 14 U.S. non-asbestos products plants, the Sales Division, and New York headquarters.
• Exposure: Asbestos dust in mining, milling and asbestos products manufacturing. Exposure at Asbestos, Quebec was probably limited to chrysotile; other production facilities may have had exposure to amosite and crocidolite. Exposure was summarized as a dust exposure score combining intensity (as a multiple of the threshold limit value) and years worked, which the authors described as 'working level years'.
• Main results:
  • Among retirees from asbestos production and processing, the excess in deaths was mainly due to cancer and respiratory disease.
  • Respiratory cancer was also high among retirees from non-asbestos production facilities.
  • Other retirees (those not from asbestos operations) had low overall mortality relative to the U.S. male population.
  • For deaths from all causes, the authors reported a good relationship between dust exposure and mortality for asbestos products retirees. The relationship was less clear for retirees from the Quebec operations.
  • At the two lower dust exposure levels examined there did not appear to be a strong relationship with mortality.
  • Looking across follow-up periods for asbestos products retirees, the authors suggested that neither respiratory cancer nor respiratory disease was much of a problem among retirees until the mid-1950s.
  • Respiratory cancer results for asbestos products workers in this study were similar to those of an earlier study of U.S. asbestos products workers aged 15 to 64.
• The authors' conclusion: The authors concluded that the similarity to the earlier study of working asbestos products employees supports the assumption that the effects of the working environment can be measured by studying retired populations. They also stated that the high respiratory cancer mortality among maintenance-service workers needs further study.
• Limitations the authors state:
  • Comparisons with U.S. male mortality are probably slightly biased, because a larger share of these men were healthy enough to work until 65, so somewhat better mortality might be expected.
  • Death certificates could not all be located, especially for Quebec retirees, many of whom apparently died outside Quebec.
  • Dust exposure levels for early periods were very rough approximations.
  • The retiree population aged over the study period, which could partly account for the rise in lung cancer seen across follow-up periods.

Topics

Medical terms in this study, explained in our Lexicon: Johns-Manville, Chrysotile.

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