Occupational exposure to vinyl chloride and mortality : findings from a follow-up of a historical cohort

Abstract

Vinyl chloride (VC), a chemical primarily used in polyvinyl chloride production, is a recognized human carcinogen (IARC Group 1). Several epidemiological studies showed increased risks among workers for different cancer entities. VC causes angiosarcoma and hepatocellular cancer. However, for cancers of the brain, the haematolymphopoietic system (leukaemia and lymphoma), and the lungs epidemiological evidence is not strong. This manuscript presents results from a recent mortality long follow-up (1970–2024) of a cohort study initiated in the 1990s within criminal proceedings. Internal analyses employed Cox proportional hazards regression to assess dose-response relationships, adjusting for age and calendar period. External comparisons utilized Italian National Institute of Statistics mortality rates for the Apulia region as the reference population. Standardized mortality ratios were calculated for specific causes of death. For outcomes with established causal links to vinyl chloride exposure, causal mortality ratios were additionally applied to strengthen causal inference. Our findings confirm the well-documented association between vinyl chloride exposure and liver cancer (hazard ratio: 4.35; 95 %CI: 1.18–16.01; standardised mortality ratio=2.21; 95 %CI:1.29–3.60), with dose-dependent risk elevation. Although characterised by high statistical uncertainty, elevated mortality for malignant neoplasms of the brain was observed, suggesting that the brain may represent another potential target organ for vinyl chloride carcinogenicity.