PFOA, PFOS, PFBA, PFBS, ADONA and GenX: Toxicological Profile for Freshwater Ecosystems

Per- and polyfluoroalkyl substances (PFAS) represent a diverse group of chemicals widely used in industrial and consumer products due to their unique physicochemical properties. This review critically examines the ecotoxicological profiles of six key PFAS—PFOA, PFOS, PFBA, PFBS, GenX, and ADONA—focusing on their effects on standard aquatic model organisms (Daphnia magna, Raphidocelis subcapitata, and Aliivibrio fischeri). The data highlight that legacy compounds such as PFOA and PFOS generally show greater toxicity, particularly with reproductive and growth endpoints in D. magna and growth inhibition in R. subcapitata, at lower concentrations compared to their short-chain analogues (PFBA, PFBS). GenX and ADONA, introduced as replacements for long-chain PFAS, have been the subject of far fewer studies. Available data, mainly from regulatory sources, suggest lower acute and chronic toxicity for these alternatives under standard test conditions. However, the lack of comprehensive data—especially regarding sub-lethal, chronic, and mixture effects—precludes firm conclusions about their environmental safety. The findings underscore the need for further ecotoxicological research on emerging PFAS and call for integrating bioassays with chemical analyses to better assess risks associated with PFAS mixtures in aquatic ecosystems.