Global trifluoroacetic acid hotspots in aquatic environments: Drinking-water risk and supply-chain responsibility.

Trifluoroacetic acid (TFA) is the most abundant per- and polyfluoroalkyl substance (PFAS) in aquatic environments, posing increasing threats to water quality and potential human exposure. However, its global risk profile and underlying drivers remain poorly understood. Herein, we integrate a CatBoost-based geospatial classifier achieving cross-validated F1 score of 0.70 and test-set sensitivity of 0.77 with an extended environmental multi-regional input-output (EE-MRIO) model to map global TFA exceedance risk in aquatic environments and trace its supply-chain drivers. We identify prominent TFA hotspots in the Yangtze River Delta, the Beijing-Tianjin-Hebei region, Western Europe, and previously unrecognized areas including the Arabian Gulf coast, with a screening-level estimate of ∼64.4 million people potentially affected by elevated source-water risk. EE-MRIO analysis further uncovers a marked mismatch between production and consumption responsibilities, indicating that part of the TFA-related water risk associated with textiles and chemicals is displaced through trade to satisfy final demand in North America and Europe, and parts of Asia. This redistribution was strongly sector-dependent, with chemical- and industrial gas-related transfers concentrated in a limited number of industrial hubs and major corridors, whereas textile-related transfers were dispersed across fragmented, multi-stage global production chains. Overall, this study provides a comprehensive supply-chain-informed perspective for mitigating TFA pollution at its source, demonstrating an approach to understanding the global drivers of environmental risks for other emerging contaminants.