Lung Cancer in Chloromethyl Ether Workers

Our plain-English summary of Lung Cancer in Chloromethyl Ether Workers, by W. Weiss, R.L. Moser, O. Auerbach (1979).

The study

• Authors: W. Weiss, R.L. Moser, O. Auerbach
• Published: American Review of Reparatory Disease, Volume 120. July 30th 1979
• Type of article: Journal article
• 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 article is about chloromethyl ethers, not asbestos. The authors studied lung cancer in male production workers at a chemical plant that made chloromethyl methyl ether, contaminated with bis(chloromethyl)ether, from 1948. They followed 1,446 men (981 unexposed, 465 exposed) from 1960 through 1975. Exposure was rated from supervisors' job rankings, and lung cancer deaths were compared with rates for white men of Philadelphia. In the whole cohort, the relative risk of lung cancer was 2.15, and risk rose with cumulative exposure. The increase was statistically significant only in men with moderate and heavy exposure. The moderate group's standardized mortality ratio was 6.92. In lightly exposed men the relative risk was less than 2.0 (6 cases observed, 3.2 expected) and not significant. Of 20 cancers in moderately and heavily exposed men, 85% were small-cell carcinoma, against 19% of 90 general-population cases. All 8 lightly exposed men with lung cancer were smokers, as were all 16 unexposed lung cancer cases with smoking information. The authors concluded that small-cell carcinoma appeared to be a specific response to these chemicals and that smoking may explain many cases among lightly exposed and unexposed workers.

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 (retrospective) cohort study of a chemical plant workforce, with review of lung cancer tissue sections and comparison with a general-population lung cancer series
• Who was studied: 1,446 male production workers aged 30 or more who worked at a Philadelphia-area chemical plant at any time between 1948 and 1960, followed from 1960 through 1975: 981 unexposed and 465 exposed
• Exposure: chloromethyl ethers (CME): chloromethyl methyl ether (CMME) contaminated with bis(chloromethyl)ether (BCME), used as an alkylating agent. Exposure was rated by supervisors on a 0 to 6 job scale and combined with exposure time into a cumulative exposure index (0 to 50.0), grouped as 0, 0.1 to 9.9, 10.0 to 24.9 and 25.0 or more. No asbestos exposure was studied.
• Main results:
  • In the entire cohort, the relative risk of lung cancer was significantly increased to 2.15, with a dose-response relationship.
  • The significant increase was limited to men with moderate and heavy CME exposure. The SMR in the moderate group was 6.92. The heavy group's value is garbled in the scan.
  • In lightly exposed men, 6 lung cancer cases were observed against 3.2 expected.
  • In the light-exposure group the relative risk was less than 2.0, and the increase was not statistically significant.
  • In moderately and heavily exposed men, 85% of 20 lung cancers were small-cell carcinoma, compared with 19% of 90 cases in the Philadelphia Pulmonary Neoplasm Research Project (p less than 0.0005).
  • In lightly exposed men, 4 of 6 lung cancer cases were adenocarcinoma against 0.74 expected, a reported significant increase.
  • Among men with lung cancer, all 8 lightly exposed cases were smokers, and all 16 of the 17 unexposed cases with smoking information were cigarette smokers. Cases in moderately and heavily exposed men occurred in increasing proportions of men who had never smoked.
• The authors' conclusion: The authors concluded that the near-exclusive occurrence of small-cell carcinoma in moderately and heavily exposed men suggests this cell type is a specific response to chloromethyl ethers. They hypothesized that cigarette smoking caused many of the cases among lightly exposed and unexposed workers.
• Limitations the authors state:
  • Deaths among employees who had left the company may have been incompletely identified through the Social Security Administration.
  • The chemical exposure estimate was a retrospective, semiquantitative and arbitrary rating.
  • Classification of lung cancer cell type is subject to variation.
  • The comparison cases were limited to men aged 45 or more, whereas 8 of the 28 exposed cases occurred in younger men.

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer, Relative Risk, Cumulative Exposure, standardized mortality ratio (SMR), Carcinoma.

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