Asbestos-associated diseases in a cohort of cigarette-filter workers

Our plain-English summary of Asbestos-associated diseases in a cohort of cigarette-filter workers, by J.A. Talcott, W.A. Thurber, A.F. Kantor, et al (The New England Journal of Medicine, 1989).

The study

• Authors: J.A. Talcott, W.A. Thurber, A.F. Kantor, E.A. Gaensler, J.F. Danahy, K.H. Antman, F.P. Li
• Journal: The New England Journal of Medicine
• Published: 1989;321(18):1220-3
• Cited by: 51 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. 000169).

Abstract

To estimate the effects on health of occupational exposure to crocidolite, a highly toxic form of asbestos, we studied a cohort of 33 men who worked in 1953 in a Massachusetts factory that manufactured cigarette filters containing crocidolite fibers from 1951 to 1957. Twenty-eight of the men have died, as compared with 8.3 deaths expected. This increased mortality was attributable to asbestos-associated diseases. Fifteen deaths were caused by cancer, as compared with 1.8 expected (relative risk, 8.2; 95 percent confidence interval, 4.6 to 13.4), including eight from lung cancer, five from malignant mesothelioma, and two from other types of cancer. There were seven deaths from nonmalignant respiratory disease, as compared with 0.5 expected (relative risk, 14.7; 95 percent confidence interval, 5.9 to 30.3), of which five were due primarily to asbestosis. In contrast, the mortality rates from cardiovascular diseases and all other causes were not increased. Four of the five living workers have pulmonary asbestosis; three of them have recently diagnosed cancers, including two additional lung cancers. We conclude that the extremely high morbidity and mortality in these workers were caused by intense exposure to crocidolite asbestos fibers.

In plain English

This study followed 33 white men making cigarette filters on September 22, 1953, at a Massachusetts factory that used crocidolite asbestos in a dry process (1951 to 1957), until death or December 31, 1988. Twenty-eight died, against 8.3 expected from U.S. white male rates (relative risk 3.4; 95 percent confidence interval 2.2 to 4.9). Cancer caused 15 deaths against 1.8 expected (relative risk 8.2; interval 4.6 to 13.4), including eight lung cancers and five malignant mesotheliomas. Nonmalignant respiratory disease caused seven deaths against 0.5 expected (relative risk 14.7; interval 5.9 to 30.3), five due primarily to asbestosis. Circulatory deaths numbered five against 4.1 expected (relative risk 1.2; interval 0.4 to 2.8), which the authors called not increased. Cancer was diagnosed in 19 men, against 3.5 expected, and asbestosis in 19. The authors could not find an association between asbestos-related deaths and either time making filters or total company employment. They noted work duration was unknown for some men and dust was measured on one day. The authors concluded that intense crocidolite exposure caused the high illness and death rates.

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 cohort study of deaths (compared with U.S. white male death rates) and of new cancer cases (compared with Connecticut Tumor Registry rates; national data used for mesothelioma)
• Who was studied: 33 white men directly involved in making cigarette filters at a Massachusetts factory on September 22, 1953. Their median age on that date was 34 (range 21 to 67). They were followed until death or December 31, 1988.
• Exposure: Crocidolite asbestos in a dry process in which asbestos, cotton and acetate fibers were mechanically mixed, carded and deposited on crepe paper. Measurements at six production locations on October 27, 1952, averaged 80 particles of asbestos dust per milliliter of air. This was within the then-current Massachusetts standard of 175 particles per milliliter but, according to the authors, far above the current federal (NIOSH) standard of 0.1 fibers per milliliter. For 23 workers, the median time spent making filters was 1.7 years (range 0.7 to 4).
• Main results:
  • All causes: 28 of the 33 men died, compared with 8.3 deaths expected (relative risk 3.4; 95 percent confidence interval 2.2 to 4.9).
  • Cancer: 15 cancer deaths were observed against 1.8 expected (relative risk 8.2; 95 percent confidence interval 4.6 to 13.4).
  • Lung cancer and other causes: eight deaths were from lung cancer (relative risk 13.1; 95 percent confidence interval 5.6 to 27.2), five from malignant mesothelioma and five from asbestosis.
  • Respiratory diseases: there were 7 deaths from nonmalignant respiratory disease against 0.5 expected (relative risk 14.7; 95 percent confidence interval 5.9 to 30.3). Five of these deaths were due primarily to asbestosis.
  • Circulatory diseases: 5 deaths were observed against 4.1 expected (relative risk 1.2; 95 percent confidence interval 0.4 to 2.8). The authors described death rates from cardiovascular diseases and all other causes as not increased.
  • New cancers: cancer developed in 19 of the 33 workers, compared with 3.5 cases expected (ratio 5.5; 95 percent confidence interval 3.3 to 8.6).
  • Lung cancer and mesothelioma cases: 11 lung cancers were observed against 0.7 expected (ratio 15.1; 95 percent confidence interval 7.5 to 27.0). Of the 5 malignant mesotheliomas, 3 were in the peritoneum and 2 in the pleura.
  • Asbestosis developed in at least 19 of the 33 workers (58 percent). This included 4 of the 5 men still alive.
  • The relative risk of death rose over the follow-up period: 2.1 in the first 10 years, 2.4 in the second decade, and 4.8 thereafter (17 deaths; 95 percent confidence interval 2.8 to 7.7).
  • The authors were unable to find an association between asbestos-related deaths and either the duration of filter making or the total time employed by the company. Asbestos-related deaths predominated in all exposure groups.
  • From first asbestos exposure to cancer diagnosis, the median time was 28 years for lung cancer (range 17 to 40) and 34 years for malignant mesothelioma (range 26 to 37).
  • Smoking: 25 workers (76 percent) were known to have smoked, and all 11 who developed lung cancer had been cigarette smokers. The authors wrote that smoking probably contributed to the high incidence of lung cancer.
  • One man made cigarette filters for less than nine months, had no other asbestos exposure, and died of asbestosis 27 years later.
• The authors' conclusion: The authors concluded that the extremely high illness and death rates in these workers were caused by intense exposure to crocidolite asbestos fibers. They also wrote that even a brief exposure to this dry process apparently resulted in a high risk.
• Limitations the authors state:
  • The dust measurements were taken on a single day and may not be representative.
  • The duration of exposure was not known for all workers.
  • Because asbestos-associated diseases developed in nearly all workers, it was difficult to identify other workplace factors that modify risk.
  • Mesothelioma and asbestosis are rare causes of death, and population rates for them are less reliable than those for lung cancer.
  • Comparisons with relative risks reported in other industries are only approximate.

Topics

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

Medical terms in this study, explained in our Lexicon: Occupational Exposure, Crocidolite, Relative Risk, confidence interval, Lung Cancer, Mesothelioma, Asbestosis.

Related studies

• Mesothelioma in manufacturers of asbestos-containing cigarette filters — J. Talcott, W. Thurber, et al. (1987)
• Asbestosis following brief exposure in cigarette filter manufacture — A.M. Goff, E.A. Gaensler (1972)
• Cigarette smoke makes airway and early parenchymal asbestos-induced lung disease worse in the guinea pig — V. Tron, J.L. Wright, et al. (1987)
• A study of the synergistic interaction of asbestos fibers with cigarette tar extracts for the generation of hydroxyl radicals in aqueous buffer solution — A. Valavanidis, H. Balomenou, et al. (1996)
• Asbestos burden in two cases of mesothelioma where the work history included manufacturing of cigarette filters — R.F. Dodson, M.G. Williams, et al. (2002)
• Asbestosis: interstitial pulmonary fibrosis and pleural fibrosis in a cohort of asbestos insulation workers: influence of cigarette smoking — R. Lilis, I.J. Selikoff, et al. (1986)

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