Occupational exposures, environmental tobacco smoke, and lung cancer

There is uncertainty regarding the association of occupational exposures with lung cancer. We have studied the association between 52 high-risk job titles and lung cancer incidence in a large prospective study, with more than 200,000 participants followed for more than 6 years and 809 incident cases of lung cancer.

Hazard ratios and 95% confidence intervals were computed by the Cox proportional-hazard regression model, adjusting for country, age, sex, social class, diet, physical activity, and smoking habits. We used a CAREX-based job-exposure matrix to infer exposure to lung carcinogens. False-positive report probability was calculated as a measure of potentially false-positive results.

Eighteen occupations, mainly related with agriculture, constructions, and metal processing, were associated with increased risk. In addition, incidence tended to increase with the number of hazardous jobs reported. When the occupations were classified according to the presumed exposure to specific carcinogenic agents, the hazard ratios were 1.5 (95% confidence interval = 1.2-1.9) for asbestos, 1.4 (1.1-1.8) for heavy metals, 1.4 (1.1-1.8) for polycyclic aromatic hydrocarbons, and 1.6 (1.2-2.1) for work-related environmental tobacco smoke. The estimated population attributable risk for employment in at least 1 at-risk job was 16% in men and 12% in women.

This large prospective study suggests that exposure to occupational lung carcinogens is still a problem, with such exposures producing moderate to large increases in risk.