Associations between agricultural use of pyrethroid insecticides and asthma: AGRICAN cohort results

Following the withdrawal of organochlorines and organophosphates, pyrethroids have become the most used insecticides in both agricultural and domestic settings.

We analyzed data from the French AGRICAN agricultural cohort to assess associations of occupational pyrethroid exposures and allergic/non-allergic asthma.

At enrollment, asthma diagnosed by a doctor was reported by 11 815 participants (7028 classified as non-allergic and 4458 as allergic based on the presence of eczema and/or hay fever). Individual exposures to 17 pyrethroids were defined in 124 992 participants, based on a combination of the history of pesticide treatment of 11 crops (grassland, vineyard, wheat/barley, corn, field peas, potatoes, tobacco, beets, sunflower, rape, fruits) and a crop-exposure matrix.

In men, no association was observed for any of the pyrethroids regardless of asthma phenotype. In contrast, in ever-exposed women, asthma risk was increased with use of any pyrethroid, both for allergic (+80 %) and non-allergic asthma (+40 %). Highest increases were observed for allergic asthma with fenpropathrin (OR = 2.00; 95 %CI:1.38-2.90), tralomethrin (OR = 1.81; 95 %CI:1.28-2.56), fenvalerate (OR = 1.81; 95 %CI:1.38-2.38), permethrin (OR = 1.78; 95 %CI:1.26-2.50) and deltamethrin (OR = 1.76; 95 %CI:1.35-2.29). Stratified analyses on women who reported living on a farm in early life showed stronger associations for non-allergic asthma. For women who reported early life living on vineyards associations with pyrethroids were stronger for both allergic and non-allergic asthma. Associations for women who lived on cattle farms were reduced for some pyrethroids.

Occupational pyrethroid exposure was positively associated with both allergic and non-allergic asthma in women but not in men.