Occupational exposure to vinyl chloride and cancer risk: a review of the epidemiologic literature

Occupational exposure to vinyl chloride (VC) is causally related to liver angiosarcoma, whereas there is inconsistent epidemiologic evidence for other neoplasms. Two pooled analyses of worker cohorts from 56 plants in North America and Europe provide the most comprehensive and updated data on cancer risk among workers exposed to VC. These included over 22,000 workers, with a total of 640,000 person-years of observation, followed-up for up to 50 years. Overall, a total of 1,778 cancer deaths were observed versus 1,829.46 expected, corresponding to a standardized mortality ratio (SMR) of 0.97 (95% confidence interval (CI)=0.93-1.02). Excluding 71 confirmed angiosarcomas, there were 60 deaths from liver cancers versus 44.35 expected (SMR=1.35, 95% CI=1.03-1.74). Lung and laryngeal cancer mortality were significantly lower than expected (SMR=0.88 and 0.59, respectively). The SMRs for soft tissue sarcoma, brain, lymphoid and haematopoietic system cancers were not materially different from unity. Thus, the aggregate data from over 20,000 VC workers in North America and Europe exclude any excess mortality from lung, laryngeal, soft tissue sarcoma, brain, lymphoid and haematopoietic neoplasms. There appears to be a slight excess of liver cancer other than angiosarcoma, which is difficult to interpret and is likely due to residual misclassification of angiosarcomas.