Agricultural exposure and risk of bladder cancer in the AGRIculture and CANcer cohort.

PURPOSE
Literature on agricultural activities and bladder cancer risk is scarce. However, farmers can be subjected to carcinogenic exposure (e.g. arsenic, previously used as a pesticide in France). This study aimed at assessing the role of a large range of agricultural activities and tasks on bladder cancer risk.

METHODS
The study population was the AGRIculture and CANcer cohort, a large prospective cohort of individuals affiliated to the agricultural health insurance scheme (MSA) in France. Incident bladder cancers were identified by cancer registries from enrolment (2005-2007) to 2009. Data on agricultural exposure during professional lifetime (5 animals, 13 crops, specific tasks) were obtained from the enrolment questionnaire. Associations between bladder cancer and agricultural exposure were analysed using a Cox model, adjusted for gender and smoking history.

RESULTS
Among the 148,051 farm owners and workers included in this analysis, 179 incident bladder cancers were identified. We observed an elevated risk among field-grown vegetable workers [HR 1.89, 95% CI (1.20-2.99)], with an exposure-response relationship with duration of work [≥30 years: HR 2.54, 95% CI (1.11-5.83), p-trend = 0.02], and higher risk among women [HR 3.82, 95% CI (1.58-9.25), p-interaction = 0.05]. Non-significantly increased risks were also observed in greenhouse farmers (HR = 1.95), pea sowing (HR = 1.84), rape sowing (HR = 1.64); several tasks involving pesticide use, especially seed treatment (HR = 1.24); and in activities and tasks potentially exposing to arsenic compounds via pesticide use (HR = 1.49) or re-entry tasks (HR = 1.63).

CONCLUSIONS
Our analyses raise the question of a possible link between agricultural activity, especially field-grown vegetables, and greenhouse cultivation and bladder cancer.