Objective Occupational exposure to agents in plastics and rubber manufacturing has been associated with elevated risk of certain cancers. We sought to evaluate cancer risk among workers employed in occupations and industries with these exposures as part of an ongoing surveillance programme in Ontario, Canada.

Methods The Occupational Disease Surveillance System (ODSS) cohort was established using workers’ compensation claims data and includes 2.18 million workers employed from 1983 to 2014. Workers were followed for site-specific cancer diagnoses in the Ontario Cancer Registry through 2016. Cox proportional hazard models were used to estimate adjusted HR and 95% CI.

Results We identified 81 127 workers employed in plastics and rubber manufacturing industries or materials processing and product fabricating occupations. Compared with all other women in the ODSS, those in materials processing occupations had an elevated rate of lung cancer (HR 1.38, 95% CI 1.20 to 1.58) that was not observed among men. An elevated rate of breast cancer was observed among female labourers (HR 1.36, 95% CI 1.01 to 1.82) and moulders (HR 1.47, 95% CI 0.91 to 2.37) in plastics and rubber product fabricating occupations. Overall, elevated rates were observed for oesophageal, liver, stomach, prostate and kidney cancer in job-specific subgroups, including mixing and blending, bonding and cementing, and labouring. There was little evidence of association for lymphatic or haematopoietic cancers.

Conclusions Findings for lung and breast cancer in women are consistent with other studies and warrant further attention in Ontario. Given the relatively young age at end of follow-up, surveillance in these workers should continue as the cohort ages.