Agricultural exposure and asthma risk in the AGRICAN French cohort

Epidemiological studies have reported an increased risk of respiratory diseases in agricultural population, but a protective “farm-effect” has also been reported for asthma. In the AGRICAN cohort, self-reported doctor-diagnosed asthma was analyzed according to allergy, in relation with history of life-time exposure to 13 crops and 5 livestock, pesticide exposure and early life on a farm, taking into account sex, age, education and body mass index. Among the 1246 asthmatics (8.0%), 505 were allergic (3.3%) and 719 non-allergic (4.6%). In multivariate analysis, a significant excess was observed, only for allergic asthma, in vine-growing (OR = 1.43, p = 0.002), fruit-growing (OR = 1.58, p = 0.001), greenhouses (OR = 1.66, p = 0.02), grasslands (OR = 1.35, p = 0.009), beets (OR = 1.52, p = 0.003) and horses (OR = 1.35, p = 0.04). Pesticide use and history of pesticide poisoning were significantly associated with allergic asthma in grassland, vineyards and fruit-growing and with non-allergic asthma in beets. Living on a farm in the first year of life tended to be protective for childhood allergic asthma in farms with livestock (OR = 0.72, p = 0.07) but deleterious in farms with vineyards, fruit or vegetables (OR = 1.44, p = 0.07). In AGRICAN, an increased risk of allergic asthma was observed with crop exposure, pesticide use and early life on a farm, especially in vine-growing, grassland, beets, fruit and vegetable-growing.