110 Investigating a cancer cluster in Ontario, Canada using historical occupational hygiene data to evaluate risk of occupational cancers

Abstract In 2022, the province of Ontario in Canada had 95,000 cancer cases diagnosed in a population of 15.11 million. The 16 most common occupational carcinogens cause 3,000 cancer diagnoses per year in Ontario. However, there is a lack of awareness of occupational cancers, with just 400 claims submitted on average per year to Ontario’s workers’ compensation insurance agency, of which 170 claims are accepted. A labour union approached the Occupational Health Clinics for Ontario Workers, Inc. (OHCOW) with a request to investigate a potential cancer cluster among a cohort of workers/retirees with exposures to blacksmithing, welding fumes, and diesel exhaust. OHCOW is a not-for-profit labour governed, worker-based network with a team of dedicated health professionals including 18 occupational hygienists. Occupational hygienists at OHCOW are trained to do retrospective exposure assessments using a combination of published data, databases of exposures, and when available, employer occupational hygiene data. Using occupational hygiene reports from the 1970s to 2010s, an occupational hygienist analyzed the workers’ exposures to IARC Group 1 carcinogens to investigate the cluster. This presentation will summarize the challenges of using historical data, the application of current evidence-based occupational exposure limits, the importance of referring to peer-reviewed published literature, and finally the outcomes of the workers’ compensation submissions.