Twin Threats in the Deepest Ocean: Novel PFAS Drive Exposure While Legacy PFAS Drive Risk

dw) but contributed minimally to risk. In contrast, long-chain PFAS (PFTrDA and PFUnDA), though less abundant, exhibited substantially higher risk potential. The novel compound F-53B was detected exclusively in Mariana amphipods. Overall, the accumulation patterns across PFAS classes reflect the combined influence of external exposure and internal partitioning constraints. These findings demonstrate that structural modification does not inherently reduce PFAS hazards and highlight the necessity of including hadal organisms in global chemical risk evaluation.