Exposure to currently used pesticides in Belgian children: Urinary biomonitoring and risk assessment of frequently detected chlorpyrifos and pyrethroid metabolites.

Human exposure to currently used pesticides (CUPs) is widespread, with children being especially vulnerable to possible adverse health effects. Assessing exposure and related risks in children is therefore essential. In this study, 6 parent compounds and 9 metabolites of a subset of CUPs were analyzed in 327 urine samples from children (4-12 years) in the ENVIRONAGE cohort, as part of the characterization of their chemical exposome. Among the targeted compounds, 3,5,6-trichloro-2-pyridinol (TCPY), 3-phenoxybenzoic acid (3-PBA) and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (trans-DCCA) were detected in > 50 % of samples, with 3-PBA showing the highest median level (0.33 ng/mL, interquartile range (IQR): 0.18-0.61 ng/mL). These metabolites reflect exposure to chlorpyrifos and pyrethroids, while other biomarkers showed low detection frequencies. The low detection frequencies might partly reflect a limited suitability of included biomarkers rather than absence of exposure. TCPY concentrations (median: 0.16 ng/mL, IQR: 0.07-0.27 ng/mL) were lower than previously reported studies, possibly reflecting the ban on chlorpyrifos in the European Union. Questionnaires on demographics, lifestyle, and dietary habits were used to identify possible exposure determinants. Risk assessment was performed by calculating estimated daily intakes (EDIs), risk characterization ratios (RCRs), and hazard indices (HI) applying a worst-case scenario; assuming metabolites were formed due to exposure to the most toxic parent compound. Time spent cycling was positively associated with levels of 3-PBA and trans-DCCA, while sampling season was identified as a significant variable for trans-DCCA, with the highest concentrations in autumn. Juice consumption was positively associated with TCPY concentrations. All risk characterization ratios for single compounds were below 1, while for two children, the HI for combined exposure to pyrethroids exceeded 1. The current study demonstrates that Belgian children are exposed to chlorpyrifos and pyrethroid pesticides, with most exposures falling within ranges considered safe under the assumed conditions.