P25-15 Contextualizing the Environmental Quality Standard of the Most Abundant PFAS: Trifluoroacetic acid (TFA)

Per- and polyfluoroalkyl substances (PFAS) currently number over 10,000 unique structures, with varying toxicity, bioaccumulation, and exposure profiles. While they are ubiquitous in the environment globally, their structural and toxicological diversity make them difficult to consider as a single chemical class. The most abundant PFAS found in the environment, by mass, is trifluoroacetic acid (TFA). This is a commonly formed degradation product from almost 2000 precursors, including plant protection products, gaseous refrigerants and propel-lants, and pharmaceuticals, which means it has multiple entry pathways into the environment. Its widespread use accounts for the prevalence of TFA and its increasing concentrations in surface water, drinking water sources, crops, and human blood. Like all PFAS, the omnipresence of TFA and the risk it poses for both human health and the environment, necessitates its consideration from a ‘One Health’ perspective. Additionally, it has been suggested to meet the criteria of a planetary boundary threat. From a regulatory perspective, several guideline values have already been established, including 60 µg/L for drinking water in Germany, 9 µg/L for drinking water in Denmarkand 2.2 µg/L for drinking water in the Netherlands [2] . In the EQS draft dossier on total PFAS it has been proposed for inclusion in the water framework directive (WFD) as the 25 th listed PFAS with Relative Potency Factor (RPF) of 0.002 (corresponding to the Dutch guideline value of 2.2 µg/L). The RPF is based on relative rat liver toxicity. Health effects in animal studies have included mild liver hypertrophy and embryo-fetal developmental toxicity in rabbits, and it is intended to be classified as a Category 1B: Presumed human reproductive toxicant under EU Regulation 1272/2008. It has also been identified as harmful to aquatic life, although it does not bioaccumulate. A finalized assessment of the aquatic ecotoxicity is still missing but UBA reports a draft environmental quality standard (EQS) of 21 µg/L, indicating that guideline values for human and environmental protection are in the same range. Recent measurements in Germany have found median TFA concentrations in precipitation of 0.21 µg/L 3 and in drinking water of 1.5 µg/L with maximum surface water concentrations exceeding 30 µg/L 4 . TFA's identified human health and environmental risks, prevalence in the environment, and exceedance of threshold values support the need for its consideration under the banner of ‘One Health’. With this motivation, we have reviewed the available aquatic ecotoxicity data to propose chronic and acute environmental quality criteria for TFA in surface waters in support of understanding its environmental relevance.