Lung cancer risk associated with occupational exposure to nickel, chromium VI, and cadmium in two population-based case-control studies in Montreal.

BACKGROUND Nickel, chromium VI, and cadmium have been identified as lung carcinogens in highly exposed cohorts. The purpose of this study was to examine the etiological link between lung cancer and these metals in occupations, that usually entail lower levels of exposure than those seen in historical cohorts. METHODS Two population-based case-control studies were conducted in Montreal, from 1979 to 1986 and from 1996 to 2001, comprising 1,598 cases and 1,965 controls. A detailed job history was obtained to evaluate lifetime occupational exposure to many agents, including nickel, chromium VI, and cadmium compounds. RESULTS Lung cancer odds ratios were increased only among former or non-smokers: 2.5 (95% CI: 1.3-4.7) for nickel exposure, 2.4 (95% CI: 1.2-4.8) for chromium VI, and 4.7 (95% CI: 1.5-14.3) for cadmium. The metals did not increase risk among smokers. CONCLUSIONS While excess risks due to these metal compounds were barely discernable among smokers, carcinogenic effects were seen among non-smokers.