Objective Occupational exposure to agents used in plastics and rubber manufacturing have been associated with elevated risk of certain cancers. We sought to estimate cancer risk among workers with a history of employment in plastics and rubber manufacturing as part of an ongoing surveillance program 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 between 1983–2014. Workers were followed for site-specific cancer diagnoses in the Ontario Cancer Registry through 2016. Cox-proportional hazard models were used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI).

Results We identified 81,127 workers (69% male) ever-employed in plastics and rubber manufacturing industries or materials processing and product fabricating occupations. Compared to all other workers in the ODSS, workers in materials processing occupations had an elevated rate of lung cancer (HR 1.11, 95% CI: 1.02–1.20), which occurred almost exclusively among females (HR 1.38, 95% CI 1.20–1.58) in sex-stratified analyses. An elevated rate of breast cancer was observed among female labourers (HR 1.36, 95% CI: 1.01–1.82) and moulders (HR 1.47, 95% CI: 0.91–2.37) in plastics and rubber product fabricating occupations. Rates were elevated for esophageal, liver, stomach, prostate, and kidney cancer in job-specific subgroups including mixing and blending, bonding and cementing, and labouring. Workers in the plastics product fabricating industry had modestly elevated rates of pancreatic and brain and nervous system cancer.

Conclusions Elevated rates of lung and breast cancer among females are consistent with other studies of women in plastics and rubber manufacturing and warrant further attention in Ontario. Results for digestive and other cancers are broadly consistent with exposure to known or suspected carcinogens in these industries and suggest new sites of potential concern.