Preliminary Assessment of Per-and Polyfluoroalkyl Substances (PFAS) Contamination in Tap Water from Selected Areas in Laguna, Philippines

Abstract

Safe drinking water remains a critical challenge in the Philippines, where rural households rely primarily on deep wells and chlorination as their sole treatment method. Despite growing international concern, Philippine water supplies have not been monitored and regulated for contamination by per- and polyfluoroalkyl substances (PFAS). This study provides a baseline assessment of two priority PFAS: perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), in household tap water samples collected from Laguna, Philippines. A validated solid-phase extraction (SPE) protocol coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed across nine sampling points to quantify PFAS occurrence. This study identified two major contamination hotspots, wherein the highest PFOS concentrations were detected in a dormitory inside the firefighting training facility, with a mean value of 29.84 ng/L and a peak concentration of 41.71 ng/L, while elevated PFOA levels were observed in a household tap water near industrial parks, with a mean concentration of 39.58 ng/L. As regional data, these results contribute to the global PFAS monitoring literature and highlight the importance of integrating science with policy to safeguard national water security.