LAUSR

Objective To estimate the attributable fraction (AF) and number of annual incident cancers among women due to occupational exposures, as part of the Canadian Burden of Occupational Cancer study. Methods Attributable fractions, calculated with Levin’s equation, used estimates of proportions of workers ever exposed (PrE) 10–50 years before diagnosis, and point/range estimates of the exposure-cancer association from the epidemiologic literature. Numbers of attributable cancers were calculated by applying AFs to 2011 Canadian Cancer Registry data. Historical exposure was derived from CAREX Canada estimates of prevalence and level of exposure. PrE was estimated from the Canadian census, labour force survey and survival probabilities. Analyses focused on 12 carcinogens with ≥5000 exposed women. Results The highest AF among women was for mesothelioma (AF=40%); 1.6% of lung and 2.6% of ovarian cancers were also attributed to asbestos. The largest number of attributable cancers was due to shift work, a probable cause of breast cancer (AF=2.0%–5.2%, 460–1180 cases), followed by solar radiation, with 415 skin cancers (AF=1.3%). Workplace exposure to environmental tobacco smoke (ETS) was associated with 5.8% (~60 cases) of lung cancers among never-smoking women, and radon exposure in buildings resulted in almost 80 lung cancers (AF=0.7%). AFs were overall higher for men, but similar between men and women for radon and ETS among never smokers. Conclusion In burden studies, assessing the impact of uncertainty in exposure and risk estimates is a challenge. The impact is, however, amplified among women because estimates are derived from studies primarily on male workers.