RT Journal Article SR Electronic T1 Ongoing risk of bladder cancer among former workers at the last benzidine manufacturing facility in the USA JF Occupational and Environmental Medicine JO Occup Environ Med FD BMJ Publishing Group Ltd SP 625 OP 631 DO 10.1136/oemed-2020-106431 VO 78 IS 9 A1 Melissa L Millerick-May A1 Ling Wang A1 Carol Rice A1 Kenneth D Rosenman YR 2021 UL http://oem.bmj.com/content/78/9/625.abstract AB Objective To determine whether there is an ongoing risk of developing bladder cancer in a previously studied cohort of workers exposed to both benzidine and dichlorobenzidine or dichlorobenzidine only in the last benzidine manufacturing plant in the USA.Methods Workers (n=488) were identified from the quarterly 941 forms the employer was required to submit to the Social Security Administration from 1960 to 1977. Exposures were assigned based on dates worked and known benzidine/dichlorobenzidine production schedules. Incidence, vital status and cause of death were determined through 2014. Analyses were restricted to white men.Results Bladder cancer incidence and mortality were significantly increased (25 incident cases, standardised incidence ratio (SIR) 2.19, 95% CI 1.42 to 3.23, and 5 deaths, standardised mortality ratio (SMR) 3.79, 95% CI 1.23 to 8.84). There were significant increases in incidence and mortality in those exposed to both benzidine and dichlorobenzidine (SIR 3.11, 95% CI 1.97 to 4.67, SMR 4.10, 95% CI 1.12 to 10.50), but not among workers exposed to dichlorobenzidine only (two incident cases, SIR 0.89, 95% CI 0.11 to 3.23 and one death, SMR 2.90, 95% CI 0.07 to 16.15). Bladder cancer incidence and mortality were increased in individuals with >20 years since last exposure with >5 years worked (six observed, SIR 5.94, 95% CI 2.18 to 12.92 and two deaths, SMR 7.93, 95% CI 0.96 to 28.65).Conclusions Incidence and mortality due to bladder cancer increased among workers exposed to benzidine but not among workers exposed only to dichlorobenzidine. The risk of incidence and death from bladder cancer remain elevated more than 20 years after last exposure to benzidine in those who worked >5 years.No data are available. This is an ongoing study.