Cancer incidence and mortality among workers exposed to benzidine

Background: A historical cohort study was conducted among 997 individuals employed at a chemical production facility to investigate whether occupational exposures to benzidine and other arylamines were associated with the increased risk of cancer. Methods: Cancers were identified from cancer registries, death certificates, and medical records. Exposures were evaluated using a job-exposure matrix. Workers were categorized into exposure groups to calculate cancer-specific standardized incidence ratios (SIRs) and perform survival analyses. Results: SIRs for cancer of the bladder (SIR=3.5; CI 1.7, 6.4), small intestine (SIR 18.4; CI 2.2, 66.4), and soft tissue including heart (SIR=11.9; CI 1.4, 42.8) were elevated among workers with the highest exposures and risk increased with increasing exposures. SIRs for several additional cancers were also elevated. Conclusion: Our results support previous findings of increased risk of bladder cancer among individuals exposed to benzidine and other arylamines. Workers may also have been at increased risk for cancers other than cancer of the bladder.