Cancer incidence and exposure to 4,4'-methylene-bis-ortho-chloroaniline (MbOCA).

To monitor the occurrence of cancer in a recently defined cohort of UK workers engaged in the manufacture of polyurethane elastomers using 4,4'-methylene-bis-ortho-chloroaniline. A cohort of 308 male production workers from seven factories have been enumerated. All employees had a minimum of 12 months employment and were first employed at one of the participating factories in the period 1973-2000. Mortality and cancer incidence data for the period 1979-2007 were compared with expected values based on national rates. Mortality from all cancers combined was below the expected value [observed (Obs) 5, standardized mortality ratio (SMR) 68]. There was a single death from bladder cancer (SMR 560). The incidence of all cancers combined was also below expectation [Obs 9, standardized registration ratio (SRR) 77]. Site-specific incidence was unexceptional except there was a non-significant excess of bladder cancer based on two cases (SRR 328). The findings for bladder cancer should be treated with caution as they relate to a relatively early period of follow-up and are based on very small numbers.