Asbestos exposure, smoking, and neoplasia

Our plain-English summary of Asbestos exposure, smoking, and neoplasia, by I.J. Selikoff, E.C. Hammond, J. Churg (JAMA, 1968).

The study

• Authors: I.J. Selikoff, E.C. Hammond, J. Churg
• Journal: JAMA
• Published: 1968;204(2):106-12
• Cited by: 303 articles, as counted by NIH iCite
• Read it: PubMed
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001462).

In plain English

The authors followed 370 men from two asbestos insulation workers' union locals in New York and Newark, New Jersey, who were alive on January 1, 1963, through April 30, 1967. All had first been exposed to asbestos dust at least 20 years earlier. Deaths were compared with numbers expected from US white male death rates, and for lung cancer also with rates that took smoking habits into account. There were 94 deaths against 47.5 expected. These included 24 from bronchogenic carcinoma, 15 from asbestosis and 10 from mesothelioma (three pleural, seven peritoneal). Among 283 men with a history of regular cigarette smoking, 24 died of bronchogenic carcinoma where 2.98 were expected. Among 87 men who never smoked cigarettes regularly, none did (0.18 expected). The authors estimated that asbestos workers who smoked had about 92 times the risk of men who neither worked with asbestos nor smoked. They cautioned that the nonsmoker finding, based on only 87 men, does not prove asbestos has no influence on nonsmokers' lung cancer risk. They concluded that exposure should be minimized and that smokers should stop.

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: Cohort follow-up of surviving union members over 52 months, comparing observed deaths with expected deaths calculated from US mortality data and from smoking-specific lung cancer rates from an American Cancer Society prospective study
• Who was studied: 370 men, members of New York Local 12 and Newark, NJ, Local 32 of the International Association of Heat and Frost Insulators and Asbestos Workers. They were the survivors on Jan 1, 1963, of an earlier cohort of 632 members and were followed from Jan 1, 1963, to April 30, 1967. Of the 370, 283 had a history of regular cigarette smoking and 87 had never smoked cigarettes regularly (48 never smoked regularly, 39 smoked only pipes or cigars).
• Exposure: Occupational asbestos dust exposure as insulation workers, mainly in construction work, beginning 20 or more years before the study period. No fiber type is specified. The authors described this exposure as comparatively light for the asbestos trades. Cigarette smoking was also studied.
• Main results:
  • Among all 370 men there were 94 deaths from all causes, compared with 47.5 expected, an excess of 46.5 deaths
  • Among all 370 men, cancer of the lung, pleura, bronchus and trachea accounted for 27 observed deaths versus 2.3 expected, a ratio of nearly 12 to 1
  • Among all 370 men, bronchogenic carcinoma accounted for 24 deaths. With both age and smoking habits taken into account, 3.16 were expected, a ratio of about 7.6 to 1.
  • Mesothelioma accounted for 10 of the 94 deaths: three pleural and seven peritoneal
  • Asbestosis accounted for 15 of the 94 deaths
  • Among all 370 men, there were eight deaths from cancer of the stomach, colon and rectum versus 1.8 expected. The authors refrained from drawing any conclusion from this.
  • Among the 87 men who never smoked cigarettes regularly (including pipe or cigar smokers only), none died of bronchogenic carcinoma, compared with 0.18 expected
  • Among the 283 men with a history of regular cigarette smoking, 24 died of bronchogenic carcinoma, compared with 2.98 expected for cigarette smokers not exposed to asbestos, a ratio of 8.05 to 1
  • For the 283 cigarette-smoking asbestos workers, only 0.26 bronchogenic carcinoma deaths would have been expected if they had neither smoked nor been exposed to asbestos. The 24 observed deaths gave an observed-to-expected ratio of 92 to 1.
  • Among the 283 men with a history of regular cigarette smoking, 78 died within 52 months versus 32.4 expected, and 24 of the 78 deaths (31%) were from bronchogenic carcinoma
  • Among the 87 men who never smoked cigarettes regularly, three died of asbestosis and one of peritoneal mesothelioma during the 52 months
• The authors' conclusion: The authors concluded that exposure to asbestos dust greatly increases the risk of lung cancer among cigarette smokers. Given the small number of nonsmokers, they concluded only that it does not greatly increase the risk among men who never smoked cigarettes regularly. They stated that occupational exposure to asbestos dust should be reduced as far as possible, that asbestos workers who do not smoke should never begin, and that those who smoke should stop immediately.
• Limitations the authors state:
  • The finding for nonsmokers rests on only 87 men and does not prove that asbestos exposure has no influence on lung cancer risk among nonsmokers
  • The 92-to-1 estimate does not take into account how much the men currently smoked
  • The smoking-specific lung cancer rates used for expected deaths were statistically unstable in some very small subgroups, and the authors arbitrarily adjusted three rates

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure.

Related studies

• Asbestos exposure and neoplasia — I.J. Selikoff, J. Churg, et al. (1964)
• Combined effect of asbestos exposure and smoking on mortality from lung cancer in factory workers — G. Berry, M.L. Newhouse, et al. (1972)
• Investigations on the effects of chronic cigarette-smoke inhalation in Syrian golden hamsters — W. Dontenwill, H.J. Chevalier, et al. (1973)
• Pulmonary fibrosis, carcinoma, and ferruginous body counts in amosite asbestos workers. A study of six cases — V.L. Roggli, S.D. Greenberg, et al. (1980)
• Tobacco consumption and asbestos exposure in patients with lung cancer: a three year prospective study — G. Hillerdal, E. Karlén, et al. (1983)
• Relation between exposure to asbestos and mesothelioma — I.J. Selikoff, J. Churg, et al. (1965)

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