Pesticide exposure profiles through tap water consumption in the NutriNet-Santé cohort in 2022: a cross-sectional analysis using the French SISE-Eaux monitoring database

Tap water contamination by agricultural pesticide residues is widespread, but exposure characteristics and potential health effects remain understudied. This study aimed to identify tap water consumption-based pesticide exposure profiles. Pesticide exposure was estimated in a subsample (n = 17,833; median age 63.1y (IQR: 55.6-71.6); 66% women) of the French NutriNet-Santé cohort by linking food frequency questionnaire water consumption data in 2022 to French tap water monitoring data (SISE-Eaux) by municipality in 2022. Exposure profiles were derived using Non-negative Matrix Factorization on lower-bound exposure estimates followed by two-step clustering. Clusters were characterized by pesticide exposure, sociodemographic characteristics, place of residence, and water consumption. Pesticide residues were quantified in 1.1% of SISE-Eaux analyses, with 0.1% exceeding regulatory limits. Approximately one-fifth of the French population has been served by tap water exceeding at least once the regulatory limit. For exposure profile analysis, 27 substances were retained. Six clusters were identified. Cluster 1 (6.7%) showed no quantified exposure, cluster 2 (71.4%) had relatively low exposure, and cluster 3 (16.8%) had moderate exposure to the substances studied. Clusters 4 (3.5%) and 5 (1.4%) were relatively highly exposed to triazines and flufenacet and to choroacetamides and their metabolites, respectively. Finally, cluster 6 (0.1%) had the highest exposure across clusters, particularly to the metabolites of metolachlor and alachlor. Higher exposed clusters lived mainly in rural northern France areas. Most groups showed relatively low exposure relative to the overall sample average, while some regions exhibited higher contamination. Further studies should examine health effects of contaminated tap water alongside other sources.