Occupation and lung cancer in nonsmokers

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.