Cancer mortality among Moscow shoe workers exposed to chloroprene (Russia)

Objectives: To assess the risk of cancer among workers of a Moscow (Russia) shoe factory exposed to chloroprene (2-chloro-1,3-butadiene) (CP). Methods: This is a retrospective cohort mortality study among 5185 shoe manufacturing workers employed between 1940 and 1976, and followed from 1979 through 1993. Exposure to CP was assessed by linking the job history with industrial hygiene data. We calculated standardized mortality ratios (SMR) using the Moscow population as reference, and conducted an internal comparison analysis based on Poisson regression modeling. Results: For the entire cohort, all-cause mortality was close to expectation and all-cancer mortality was increased. There was an increase in the mortality from liver cancer (SMR = 2.4, 95 percent confidence interval [CI] = 1.1-4.3), kidney cancer (SMR = 1.8, CI = 0.9-3.4), and leukemia (SMR = 1.9, CI = 1.0-3.3). Mortality from liver cancer and leukemia was associated with various indicators of CP exposure. A similar, although less consistent, pattern was found for kidney cancer mortality; while for the remaining neoplasms, no association was suggested with CP exposure. Conclusions: The association between CP exposure and risk of leukemia may be due to concomitant exposure to benzene. The results for liver cancer point towards a carcinogenic effect of CP.