Pesticide exposure profiles through tap water consumption in the NutriNet-Santé cohort in 2022

Abstract Background Pesticide residues in tap water from past and current agriculture are widespread, but health effects of exposure to individual pesticides and mixtures are understudied. This study identifies pesticide exposure profiles from tap water to support future research. Methods Individual pesticide exposure through tap water was estimated in a subsample (n = 17,833; mean age 62y (±11.9y); 66% females) of the French NutriNet-Santé cohort by linking 2022 semi-quantitative food frequency questionnaire data to French tap water monitoring data (SISE-Eaux) by region of residence. Exposure profiles were derived using Non-Negative Matrix Factorization on lower-bound exposure estimates followed by two-step clustering. Results Overall, 9.3% of plant protection product samples contained quantified residues and 2.0% exceeded regulatory limits (about a third of the French population experienced at least one exceedance) with northern France most affected. 27 of these substances (active substances and metabolites) were retained for exploratory analyses (those with >1% of values quantified and <50% of municipalities missing). Six clusters were identified. Exposure levels were defined in relation to the overall sample. Cluster 1 (6.7%) had the lowest exposure, cluster 2 (71.4%) had low exposure, and cluster 3 (16.8%) had moderate exposure to the substances studied. Cluster 4 (3.5%) was heavily exposed to triazines and flufenacet. Cluster 5 (1.4%) showed high exposure to chloroacetamides and their metabolites. Cluster 6 (0.1%) had the highest exposure, particularly to the metabolites of metolachlor and alachlor. The clusters with the highest exposure were mainly located in rural areas in the northern France. No acceptable daily intake of any substance with a defined limit was exceeded. Conclusions A large part of the sample showed low overall exposure, although some regions were at higher risk. Further studies are needed to assess links between pesticide exposure in tap water and health. Key messages • Most individuals had relatively low pesticide exposure in tap water, but some high-exposure clusters were found, requiring targeted health risk investigation. • Even though acceptable daily intake thresholds were not exceeded from tap water alone, these preliminary findings underline the importance of including other exposure pathways.