Occupation and lung cancer in nonsmokers

Our plain-English summary of Occupation and lung cancer in nonsmokers, by J.S. Neuberger, R.W. Field (Reviews on Environmental Health, 2003).

The study

• Authors: J.S. Neuberger, R.W. Field
• Journal: Reviews on Environmental Health
• Published: 2003;18(4):251-67
• Type of article: Review
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Lung cancer remains a significant burden on society, with approximately 157,200 deaths from this disease in 2003 occurring in the United States alone. Smoking causes the vast majority of cases (and deaths) from lung cancer, occupation may account for as many as 16,700 of such deaths. To examine the influence of occupation independent of smoking, we reviewed the literature on occupational lung cancer in nonsmokers. We found that most individual studies and summaries of occupational lung cancer are based on data having a heavy preponderance of male smokers. Relatively little data are available concerning females and nonsmokers. Specific dose-response information is often lacking. Although many studies have been adjusted for smoking, there remains a significant potential for residual confounding because of the overwhelming importance of smoking in the etiology of this disease. Our review has found some evidence that asbestos, environmental tobacco smoke, and radon decay products (progeny) are occupational carcinogens in nonsmokers. Increased risk for lung cancer might also occur in nonsmokers from occupational exposure to arsenic. Nevertheless, for many agents and occupations occupations or industries listed in the database of the International Agency for Research on Cancer (IARC), we could not locate any study that found them to be occupational risk factors for lung cancer in nonsmokers. Thus, considerable uncertainty exists about their ability to cause lung cancer in the nonsmoking working population. We discuss problems with the original occupational studies and the IARC list of carcinogens. Besides the absence of information on nonsmokers, these problems include lack of sufficient detail on exposure to the primary agent of concern and to other occupational lung carcinogens. Further research on occupational causes of lung cancer in nonsmokers should be given high priority.

In plain English

This article was a review of published research on whether jobs and workplace exposures cause lung cancer in people who do not smoke (never-smokers and ex-smokers). The authors examined summaries from the International Agency for Research on Cancer (IARC) and searched MEDLINE from 1977 through 2002. They kept studies that analyzed nonsmokers specifically. They reported that IARC publications gave no data on nonsmokers for any of the listed workplace lung carcinogens. Among the studies reviewed, a Missouri study of nonsmoking women reported an odds ratio of 3.5 (95% CI 1.2 to 10.0) for asbestos exposure. A multicenter US study reported 2.0 (95% CI 0.9 to 4.3) for nonsmokers who reported asbestos exposure. The authors classed asbestos, environmental tobacco smoke and radon decay products as probable occupational lung carcinogens in nonsmokers, and arsenic as possible. For the remaining 12 IARC agents they found limited or no information. The authors concluded there was at least some evidence that lung cancer may occur from these exposures without active smoking. They noted likely residual confounding by smoking, limited exposure measurement and few data on women.

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: Literature review of IARC summary publications and published studies that evaluated nonsmokers specifically
• Who was studied: Published studies found through a MEDLINE search from 1977 through 2002 that specifically evaluated nonsmokers (never-smokers and ex-smokers). Studies that did not consider smoking, or that only adjusted for it, were excluded.
• Exposure: Workplace lung carcinogens and occupations listed by IARC in Group 1, including asbestos, arsenic, radon decay products (progeny) and environmental tobacco smoke, plus occupation in general
• Main results:
  • The IARC publications presented no data on whether any of the listed agents cause cancer in nonsmokers.
  • Based on their criteria (statistically significant results in two or more studies for probable, one study for possible), the authors listed asbestos, environmental tobacco smoke and radon decay products (progeny) as probable occupational lung carcinogens in nonsmokers, and arsenic as possible.
  • In a reviewed Missouri study of white nonsmoking women (429 cases and 1,021 controls), asbestos exposure was associated with an odds ratio of 3.5 (95% CI 1.2 to 10.0). For asbestos exposure of more than 9 years the risk was 4.6 (95% CI 1.1 to 19.2).
  • In a reviewed US multicenter hospital-based study (Muscat et al.), the odds ratio for nonsmoking subjects who reported asbestos exposure was 2.0 (95% CI 0.9 to 4.3). Specific occupations that might be considered asbestos-related did not show an increased risk.
  • In a reviewed study by Morabia et al., never-smokers exposed to asbestos had increased risks of 3.8 (less than 10 years of exposure) and 4.9 (more than 10 years). No case or control numbers or significance tests were given for these categories.
  • In a reviewed study of women in Shenyang and Harbin, China, the increase in risk for asbestos dust exposure among nonsmokers (OR 3.0) was not statistically significant.
  • For the remaining 12 IARC Group 1 agents, the authors found limited or no information implicating them as lung cancer risk factors in nonsmokers.
• The authors' conclusion: The authors concluded that for asbestos, environmental tobacco smoke and radon decay products in the workplace there was at least some evidence that lung cancer may occur without active smoking, with arsenic also a possibility. They concluded that the listed carcinogens should in most cases be understood as co-carcinogens along with smoking, and that future research should focus on nonsmokers.
• Limitations the authors state:
  • Even where studies adjusted for smoking, residual confounding by smoking is likely.
  • Exposure assessment in the studies was often very limited, for example relying on years on the job or job type.
  • The information is mainly about males; exposures unique to women have been studied much less.
  • Some studies defined a never-smoker as someone who had smoked up to 400 cigarettes, which the authors considered high.
  • Genetic susceptibility was virtually ignored in the studies.
  • The list of probable and possible carcinogens in nonsmokers may change as new studies appear.

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Dose-response relationship, Confounding, Etiology, Occupational Exposure, IARC.

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• Human cancer from environmental pollutants: the epidemiological evidence — P. Boffetta (2006)
• Asbestos is still with us: Repeat call for a universal ban — C. Ramazzini (2011)
• A ban on asbestos must be based on a comparative risk assessment — M. Camus (2001)

Browse more research in Reviews on Environmental Health, or return to medical research.