Prenatal Exposure to Emerging Pesticides and Childhood Allergy Risk: A First Mixture Assessment in an Urban Cohort

Pesticide gestational exposure may contribute to the development of allergies in childhood, yet evidence on its health impact on urban populations remains limited. This study investigates the association between prenatal exposure to individual and mixed pesticides and allergic outcomes, including asthma, wheezing, and eczema, at age 6 in 387 mother-child pairs from the LiNA cohort. Forty pesticides and metabolites were detected in urine during pregnancy through non-targeted screening, and 11 were selected (detection rate≥17%) for further analysis. Multivariable logistic regression models adjusted for covariates revealed statistically significant associations between dihydroxy-pyrimethanil and asthma (aOR=1.36, 95% CI: 1.04–1.80), and fluazifop-desbuthyl and wheezing (aOR=1.15, 95% CI: 1.01–1.31). No significant associations were observed for eczema. The mixture effect analysis with weighted quantile sum (WQS) regression showed that higher pesticide co-exposures significantly increased wheezing odds (aOR=2.08, 95% CI: 1.21–3.56). The main components of the WQS index were fluazifop-desbuthyl, flonicamid, hydroxy-metazachlor, and terbuthylazine, accounting for 67% of the overall dose-additive effect. These findings suggest that prenatal exposure to pesticides at dietary levels may increase the risk of childhood asthma and wheezing. Further epidemiological studies should replicate our findings by considering exposures to other pesticides of concern and their metabolites.