Determination of Perfluorooctanoic Acid and Perfluorooctane Sulfonate Water Quality Criteria for Ecosystem Protection of Laguna Lake, Philippines

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are organic chemicals which pose concerns in the environment due to their persistence and bioaccumulative properties. This study used Assessment Factors and Species Sensitivities Distributions to derive specific thresholds to protect the ecosystem in the Laguna Lake, Philippines from risks posed by the toxicity of PFOS and PFOA using available ecotoxicity data for local species. For Assessment Factor method, the U.S. Environmental Protection Agency guideline for the narrative Tier II criteria was suitable based on the available toxicity data with calculated maximum concentration threshold for PFOS and PFOA of 0.51 and 0.75 mg L-1, respectively, and continuous maximum concentration values of 0.06 and 0.08 mg L-1, respectively. For the methods using Species Sensitivity Distribution (SSD), PFOS and PFOA thresholds extrapolated using factors for small datasets were 0.046 and 0.088 mg L-1, respectively. Lastly, PFOS and PFOA Hazardous Concentration (HC5) extrapolated from the weighted average SSD model estimates were 0.061 and 0.078 mg L-1, respectively. The results can serve as the first regulatory and risk assessment basis for aquatic ecosystem protection against risks posed by emerging contaminants in the lake.