A cohort study on vinyl chloride manufacturers in Italy: study design and preliminary results.

A cohort mortality study of 5000 vinyl chloride manufacturers is ongoing in 9 Italian plants. They represent the entire workforce of those ever employed in the production of the monomer and its polymerization. The objectives of the study are to investigate the mortality of the exposed population and to clear up the carcinogenic spectrum of vinyl chloride. This article gives the results for 3 out of 9 plants, Rosignano, Ferrara and Ravenna, which represent about 25% of the total cohort. The expected deaths have been calculated using the mortality rates of the Italian population. For the deceased persons information from the death certificates were used in the analysis of mortality; additional clinical and pathological data were collected (best pathological evidence, b.p.e.). In Ferrara a statistically significant excess for all malignant tumors and lung cancer was detected. In Rosignano and Ravenna the number of observed deaths were small and therefore no comments can be made on cancer mortality. The cohort study is ongoing in the 6 remaining cohorts and the future analysis will consider duration and level of exposure and latency.