Emerging PFAS alternatives: Unveiling environmental fates and ecological risks

PFAS pose significant threats to global ecosystems. In response to the phase-out of traditional PFAS, emerging alternatives are being deployed. Among these, four representative alternatives, hexafluoropropylene oxide-dimer acid (HFPO-DA), dodecafluoro-3H-4,8-dioxanonanoate (ADONA), 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFAES) and 6:2 fluorotelomer sulfonamide alkylbetaine (6:2 FTAB), have seen a dramatic surge in global usage, raising urgent concerns about ecological impacts. This review systematically views the distribution, migration characteristics and toxicity effect assessment of these four alternatives. Research shows that due to the different types of alternatives used in different countries, their distribution exhibits regional differences, but they can migrate over long distances, thus appearing all over the world. In terms of toxic ecological assessment, the alternatives cause multi-dimensional damage to biological cells and organ functions, leading to abnormal functions of individual organisms, changes in population structure, and even threatening the stability of the ecosystem. In general, the research on the combined exposure toxicity mechanism and global monitoring of the alternatives remains the challenge currently. In the future, it is necessary to strengthen the collaborative research on multi-medium environments, improve the toxicity assessment system and combine artificial intelligence to provide a scientific basis for their risk management and environmental governance.