A unified liquid chromatography-mass spectrometric approach combining targeted and untargeted analyses for community exposure profiling in wastewater

Wastewater-based epidemiology (WBE) has strong potential for community-level environmental exposure surveillance, but current applications remain limited in chemical scope and rarely integrate biomarker discovery with targeted quantification. Here, we developed an integrated wastewater exposomics framework combining untargeted Phase II metabolite profiling with targeted measurement of established volatile organic compound (VOC) biomarkers to characterize community-level chemical exposure. Across sixteen sewersheds in Louisville Metro, Jefferson County, Kentucky, including eleven neighborhood catchments and five centralized treatment facilities, we detected 194 Phase II metabolites derived from 145 parent xenobiotics, including mercapturic acids, glucuronides, and sulfates associated with aldehydes, aromatic hydrocarbons, epoxides, and related environmental chemicals. Several metabolites were consistently detected across sites, whereas many exhibited marked spatial heterogeneity, with greater variability at the neighborhood scale. Targeted liquid chromatography-mass spectrometry analysis of VOC biomarkers similarly revealed greater variability in neighborhood catchments than in treatment-center influent. Together, these findings demonstrate that integrating untargeted and targeted approaches extends WBE beyond limited target panels, enabling broader biomarker coverage and improved spatial resolution of community-level chemical exposures. Further refinement of normalization strategies, metabolite libraries, and data integration will enhance its utility for population-level exposure assessment.