Occupational
Occupational exposure and risk of bladder cancer: findings from the Agricultural Health Study Shuai Xie* Shuai Xie Xie Xie Xie Xie Xie Xie Xie Xie National Cancer Institute
Background: Occupational exposures are a leading cause of bladder cancer, with numerous agents (e.g., engine exhausts, solvents, and metal-working fluids) suspected as carcinogens. Farmers are frequently exposed to some of these agents during farm tasks (e.g., repairing engines, painting, and welding metal).
Methods: We evaluated the association between farming tasks and bladder cancer risk in the Agricultural Health Study, a large prospective cohort study which includes farmers in Iowa and North Carolina. Farmers (n=22,234) reported the frequency of farm tasks at enrollment (1993–1997). We used Cox proportional hazards models with age as the time scale to estimate HR and 95% CI for a 28-year follow-up period (1993-2021), adjusting for cigarettes smoking, sex, race, body mass index, and pipe smoking.
Results: Overall, 312 farmers were diagnosed with bladder cancer and provided information about farm tasks. Driving diesel tractors (90%), driving gasoline tractors (68%), and driving trucks (67%) were the most frequently reported farming tasks. The frequency of grinding metal was strongly correlated with welding (r=0.66) and moderately correlated with engine repair (r=0.43). We observed elevated risk with weekly/daily grinding metal (HR=1.26, 95% CI: 0.92-1.71), monthly welding (HR=1.31, 95% CI: 1.01-1.73), and monthly engine repair (HR=1.42, 95% CI: 1.08-1.86). Additionally, the frequency of painting was moderately correlated with solvent use (r=0.42). Monthly solvent use was associated with a higher risk of bladder cancer (HR=1.59, 95% CI: 1.08-2.36).
Conclusions: Farming tasks are important sources of exposure to potential bladder carcinogens among farmers. Increased risks observed from welding, engine repair, and solvents add to emerging literature supporting a link between these occupational exposures and bladder cancer etiology. As some farmers are also employed off the farm, additional exploration of these exposures in occupations off-farm are warranted.