The mortality in a cohort of workers at a
vinyl chloride polymerization plant has been updated, extending the period of observation in the original study from 1974 to 1986. Workers at this plant may have been exposed to
vinyl chloride monomer and/or
polyvinyl chloride dust, or may have had no exposure to either substance. Seventy-six percent of the work force worked in jobs with potential exposure to
vinyl chloride monomer. Among the total cohort, statistically significant excess risks were observed for liver, lung, and
brain cancer. For the subcohort of workers exposed to
vinyl chloride monomer, the standardized mortality ratio (SMR) for
liver cancer was 333 (90% confidence interval (CI) 202 to 521). However, there were no significant excesses of either brain (SMR = 145, 90% CI 78 to 249) or
lung cancer (SMR = 115, 90% CI 96 to 141). To investigate dose response, nested case-control studies for liver, brain, and
lung cancer were conducted among the total cohort (including the nonexposed). For these studies there were two exposure variables, cumulative dose of
vinyl chloride monomer and cumulative dose of
polyvinyl chloride dust. Cumulative dose was defined as the product of level and duration of exposure. The only significant association between disease risk and cumulative dose was for
liver cancer and cumulative dose of
vinyl chloride monomer. Further division of the
liver cancers into
angiosarcoma (n = 12) and other
liver cancers (n = 7), based on review of death certificates and medical records, showed that the dose response existed only for
angiosarcomas.