Next Generation Risk Assessment of Emerging PFOA Alternatives Using Integrated New Approach Methodologies

The global restriction of legacy per- and polyfluoroalkyl substances (PFASs), such as perfluorooctanoic acid (PFOA), has led to increased production and environmental occurrence of emerging alternatives. This study applied a next generation risk assessment (NGRA) framework to evaluate and compare the local environmental risks of eight PFOA alternatives using multiple lines of evidence from new approach methodologies (NAMs). Targeted chemical analysis was conducted to quantify environmental concentrations in wastewater and surface waters near an industrial source. Hazard characterization integrated in silico modeling, in vitro assays using zebrafish liver cells, in vivo zebrafish embryo toxicity tests, and transcriptomic profiling. Multiple points of departure (PODs), including conventional effect concentrations, benchmark concentrations (BMC), transcriptomic POD (tPOD), and species sensitivity distributions (SSD), were derived. The results showed that HFPO-TA and HFPO-TeA were cytotoxic, while HFPO-DA, HFPO-TA, and HFPO-TeA caused significant embryo toxicity. HFPO-TeA emerged as the most potent alternative, with transcriptomic signatures implicating disruption of metabolic and cardiovascular functions. Risk quotients (RQ) for HFPO-DA exceeded concern thresholds across end points, while those for HFPO-TA and HFPO-TeA declined with appropriate assessment factor adjustments. These findings highlight potential local environmental risks from PFOA alternatives and demonstrate the utility of NAM-based NGRA frameworks.