Membrane-Water Partition Coefficients of Per- and Polyfluoroalkyl Substances (PFAS): A Promising Descriptor of their Bioaccumulation and Toxicity

“Per- and polyfluoroalkyl substances (PFAS) are chemicals of high environmental concern due to their widespread presence and high persistency in aquatic and terrestrial ecosystems. Yet, current PFAS exposure and risk assessment are inadequate, as they focus on only a limited subset of compounds, overlooking the large variation in chemical structures and properties of the more than 6000 CAS registered PFAS. Since it is not feasible to test the plethora of FPAS for their environmental fate and effects, a descriptor that is indicative of PFAS exposure, bioaccumulation and ecotoxicity is urgently needed. Classical descriptors like the octanol-water partition coefficient, have proven of limited value in evaluating the environmental behavior of PFAS, due to their unique characteristics and their affinity for phospholipids. Alternatively, the phospholipid membrane-water partition coefficient (Kmw), which determines the membrane permeability of a compound, could be used to assess the environmental fate,
bioaccumulation and ecotoxicity of PFAS. Since data on the membrane-water partitioning of PFAS are scarce, the aim of this study was to measure the Kmw for a set of 17 PFAS with different structures, varying chain length and functional groups. To this end, two different methods were employed for the determination of Kmw. The first method was based on the evaluation of the retention capacity of the compounds on a chromatographic column coated with immobilized artificial membrane phospholipids
(IAM-HPLC). The second method was based on the sorption of the compounds on solid supported lipid membranes (SSLM). Preliminary results of the first method (for 5 PFAS) aligned with Kmw values previously reported in literature. Both chain length and polar head played a role in the membrane affinity of the tested PFAS. The SSLM experiments are still ongoing and results were not available by the time of abstract submission. Overall, Kmw could be considered a useful descriptor of the bioaccumulation potential and toxicity of PFAS and consequently contribute to a more reliable environmental risk assessment of these forever chemicals.”

(Citation: Xie, G., Spyridoula Gkika, I., Chen, J., et.al. – Membrane-Water Partition Coefficients of Per- and Polyfluoroalkyl Substances (PFAS): A Promising Descriptor of their Bioaccumulation and Toxicity – SETAC Europe 35th Annual Meeting, Vienna, Austria, 11-15 May 2025, p.183)