Citation:

Yang, D., J. Han, D. Ross Hall, J. Sun, J. Fu, S. Kutarna, K. Houck, C. LaLone, J. Doering, C. Ng, AND H. Peng. Nontarget Screening of Per- and Polyfluoroalkyl Substances Binding to Human Liver Fatty Acid Binding Protein. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 54(9):5676-5686, (2020). https://doi.org/10.1021/acs.est.0c00049

Impact/Purpose:

Per- and polyfluoroalkyl substances (PFASs) are widespread environmental contaminants and recent nontargeted analysis had identified over 1000 such chemicals. Prioritization of these PFASs for health concerns requires novel approaches capable of rapidly assessing these large numbers. A prioritization method was developed that provides a means to rapidly screen complex environmental mixtures to identify perfluorinated chemicals that can bind human liver FABP. Binding to hlFABP is an indicator of the ability of the ligands to interact with human physiological systems, affects PFASs toxicokinetics and can deliver lipophilic ligands to important targets of PFAS activity, i.e. the peroxisome proliferator-activated receptors. Thus the approach can be used to prioritize PFASs for more detailed assessment based on environmental prevalence and bioactivity. In addition, the method identified nonfluorinated ionic surfactants, proposed as environmentally safe PFAS replacement chemicals, as hlFABP ligands in fire-fighting foam.

Description:

More than one thousand per- and polyfluoroalkyl substances (PFASs) have been discovered by nontarget analysis (NTA), but their prioritization for health concerns is challenging. We developed a method by incorporating size exclusion column co-elution (SECC) and NTA, to screen PFASs binding to human liver fatty acid binding protein (hL-FABP). Of 74 PFASs assessed, 20 were identified as hL-FABP ligands. Increased PFASs binding affinities correlate with stronger responses in ESI- and longer retention times on C18 column. This is well explained by a mechanistic model incorporating polar and hydrophobic interactions. Encouraged by this, we then developed a SECC method to identify hL-FABP ligands, and all 8 high-affinity ligands were selectively captured from 74 PFASs. The method was further applied to an aqueous film-forming foam (AFFF) product in which 31 new hL-FABP ligands were identified. Suspect screening revealed these ligands as analogues of perfluorosulfonic acids, and homologues of alkyl ether sulfates (C8- and C10/EOn). The SECC method was then applied to AFFF-contaminated surface waters. In addition to PFOS and PFHxS, eight other AFFF chemicals were discovered as novel ligands, including four C14- and C15/EOn. This study implemented a high-throughput method to prioritize PFASs and revealed the existence of many previously unknown hL-FABP ligands.

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