Occupational Benzene Exposure and Cancer Risk among Chinese Men: A Report from the Shanghai Men's Health Study

Background: Benzene exposure has been associated with increased risk of leukemia and other cancers; however, epidemiologic evidence is inconsistent for the latter, and confounding from smoking and alcohol was rarely adjusted. Methods: We investigated associations between occupational benzene exposure and risk of leukemia, lymphoma, myeloma, and lung, stomach, liver, and kidney cancers in a population-based cohort of 61,377 men, ages 40 to 74 years. A job-exposure matrix, constructed by industrial hygienists specifically for the study population, was used to derive cumulative benzene exposure from all jobs held. Cox regressions were performed to estimate adjusted HRs (aHR) and 95% confidence intervals (CI) for benzene-cancer risk associations with adjustment for potential confounders. Results: Over 15 years of follow-up, 1,145 lung cancer, 656 stomach cancer, 445 liver cancer, 243 kidney cancer, 100 leukemia, 124 lymphoma, and 46 myeloma cases were identified. Benzene exposure >550 mg/m(3) was associated with an increased risk of leukemia (aHR = 2.3; 95% CI, 1.1-4.5), lung cancer (aHR = 1.2; 95% CI, 1.0-1.6), and stomach cancer (aHR = 1.4; 95% CI, 1.0-1.9); benzene exposure was associated with early cancer diagnosis age. The benzene-leukemia and benzene-stomach cancer associations followed a linear dose-response pattern (P-linear = 0.016 and 0.023), whereas the benzene-lung cancer association was evident at higher exposure levels (P-nonlinear = 0.027). Alcohol consumption modified the benzene-leukemia association (aHR = 3.0; 95% CI, 1.1-8.3 for drinkers and aHR = 0.9; 95% CI, 0.4-2.0 for nondrinkers, P-interaction = 0.047). Conclusions: Benzene exposure was associated with an increased risk of leukemia, stomach cancer, and lung cancer. Alcohol consumption may modify the benzene-leukemia association, although estimates are imprecise. Impact: Our study provides additional evidence that benzene exposure increases cancer risk beyond leukemia, information important for policymakers to develop programs to mitigate cancer risk among benzene-exposed workers.