Incidence of cancer among vinyl chloride and polyvinyl chloride workers: further evidence for an association with malignant melanoma.

Abstract

In a previous report1 we presented results of a mor tality study in a cohort of 454 male workers producing vinyl chloride and polyvinyl chloride which gave sup port to the observations from animal studies2 that vinyl chloride (VCM) may act as a multicarcinogen in man. We report here our finding of two new cases of malignant melanoma of the skin in the extended fol low up period 1980-4 versus 0-3 expected, giving six cases versus IT expected overall. Salmon discussed the importance of considering that less specific tumours might also be induced by exposure to VCM, and that high background incidences of such tumours make it difficult to show an increased incidence.3 He found it difficult to dismiss the excess of malignant melanoma in the study population as being the result of confounding factors, owing to the lower back ground incidences and the fact that the confounding variables (race, sunlight exposure) are more connected with geography than with personal habits, and there fore less likely to vary between control and exposed populations. Salmon also suggested that exposure to ethylene dichloride should be taken into consideration in our study population since it had been used in the process on site,3 and he suggested that our data should be reviewed with exposure to ethylene dichlo ride in mind. Since there was an increase in production and in the number of employees during the work period in which members were recruited to the cohort, the observation period was short for some of the members.1 Associations between occupational exposure fac tors and malignant melanoma of the skin have been suggested by some authors. In a study based on a proportionate mortality analysis Thomas and Decoufle found increased mortality of malignant melanoma among white male pharmaceutical production workers.4 Alderson and Rushton found