An epidemiological study of workers exposed to vinyl chloride in the plants of Ferrara, Rosignano and Ravenna

The aim of the present study is to investigate cause-specific mortality among male workers employed in vinyl chloride manufacture and polymerization in three Italian plants located in Ferrara, Rosignano and Ravenna. The cohorts include all workers hired between start of operation and, respectively 1985, 1978 and 1985, amounting to 418, 206 and 635 subjects followed up for mortality until 1996 (Ferrara and Rosignano) and 1997 (Ravenna). Cause specific SMRs (Standardized mortality ratios) were computed. Expected figures were obtained from mortality rates for the population resident in the region where the plant was located, for each SMR value a 90% confidence interval (CI) was calculated on the assumption of a Poisson distribution. The study detected an increased mortality for primary liver cancer in all three plants; SMR values were 444 in Ferrara (4 Obs. 90% CI 160-1069), 200 in Rosignano (1 Obs. 90% CI 10-869) and 375 in Ravenna (3 Obs. 90% CI 110-1038). In the pooled cohort liver cancer SMR was equal to 364 (8 Obs. 90% CI 108-390). In one plant, Ferrara, observed mortality was above the expected for lung cancer, SMR = 146 (14 Obs. 90% CI 89-229) and for larynx cancer, SMR = 500 (4 Obs. 90% CI 174-1167). One death from pleural cancer was observed in Rosignano (SMR = 1000 90% CI 47-4331). A non significant increase was detected for liver cirrhosis, in Ferrara (SMR 108, 6 Obs. 90% CI 73-332) and Rosignano (SMR 129, 3 Obs. 90% CI 35-332). The study results are confirming the carcinogenic action of vinyl chloride on the liver, they are pointing to its possible role in lung cancer development, as already shown for workers employed in Porto Marghera; an increased risk for larynx cancer is also shown.