Occurrence and Risk Assessment of Per-and Polyfluoroalkyl Substances (PFAS) in Wastewater and Drinking Water in Colombia

Per- and polyfluoroalkyl substances (PFAS) are persistent, mobile contaminants of global concern. However, data from tropical developing regions remains limited. This study characterized PFAS in Colombian wastewater treatment plants (WWTPs; influents/effluents) and drinking-water distribution systems and screened ecological and human-health risks. Ecological risk used the hazard quotient (HQ); human risk considered drinking-water exposure in 7 year-old children. Samples were analyzed by liquid chromatography–tandem mass spectrometry. The mean total PFAS was 6.00 ng·L–1 in influents and 5.51 ng·L–1 in effluents, indicating minimal removal and predominantly domestic sources. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were most prevalent. In drinking water, PFAS were consistently low and below the U.S. Environmental Protection Agency maximum contaminant levels of 4 ng·L–1 for PFOS and PFOA and 10 ng·L–1 for perfluorononanoic acid (PFNA) and perfluorohexanesulfonic acid (PFHxS), likely reflecting pristine Andean headwaters and limited fluorochemical industry. Ecological screening indicated potential concern (mean HQ for PFOS = 3.62; for PFOA = 1.72), whereas noncarcinogenic risk from drinking-water exposure was negligible. Findings confirm widespread PFAS presence with low intercity variability, underscore ecological risks despite low human exposure via drinking water, and support expanded monitoring (including precursors and nontarget PFAS) and targeted risk-management strategies for tropical regions.