CANCER MORTALITY AMONG WORKERS WITH BENZENE EXPOSURE

We updated a cohort mortality study of 4,172 workers at a chemical pla nt to examine cancer mortality among workers exposed to low levels of benzene. Overall mortality [standardized mortality ratio (SMR) = 1.0; 95% confidence interval (CI) = 0.9-1.1] and cancer mortality (SMR = 1. 0; 95% CI = 0.8-1.3) rates were at expected levels for production work ers with benzene exposure We observed elevated, albeit imprecise, rate s of leukemia (SMR = 2.3; 95% CI = 0.7-5.3) and multiple myeloma (SMR = 2.3; 95% CI = 0.7-9.4) in this group of workers. The leukemias and m ultiple myelomas occurred predominantly among workers 20 or more years after first exposure. The leukemias were not restricted to acute myel ogenous subtypes, and they occurred predominantly among workers hired before 1950 at exposure levels lower than previously reported. Leukemi a (SMR = 1.3; 95% CI = 0.62-2.4) and multiple myeloma (MR = 1.2; 95% C I = 0.3-2.9) rates were at expected levels among maintenance workers w ith intermittent high exposure to benzene. These findings provide evid ence on both sides of the debate about whether low benzene exposure in creases the risk of multiple myeloma and all types of leukemia.