Aqueous film forming foams (AFFF) developed in the 1960s by the United States Navy and the 3M Company have been widely used. Exposure to poly- and perfluoroalkyl substances (PFASs) in AFFF products has been linked to elevated concentration in blood serum. Although multiple C8-PFASs (e.g., PFOS and PFOA) have been phased out of production due to toxicity, persistence in the environment, and bioaccumulative potential, PFASs with similar structures continue to serve industrial needs. Due to the large number of commercially available and environmentally detected PFASs, the bioaccumulative potential of PFASs used to replace legacy structures is difficult to assess. In this study, a comprehensive PFAS screening library was compiled, and an HPLC-Qtof-MS method was applied to identify and quantify PFASs in an AFFF product. Human serum albumin (HSA) was then exposed to a series of AFFF dilutions using equilibrium dialysis to screen for preferential associations of specific PFASs with the protein. A broad spectrum of PFASs, including C4-PFASs, exhibited strong associations with HSA. Application of non-linear binding models implied high affinity binding at specific sites. After precipitation of the protein and removal of free PFASs in solution, the hydrolyzed HSA pellet contained low levels of strongly bound PFASs. Further analysis using 19F NMR titrations provided insight into protein binding mechanisms. Different interactions with HSA were observed for PFASs in AFFF compared to individual PFAS compounds. The combination of experimental and modeling techniques applied provides value in rapidly assessing the bioaccumulate potential of emerging PFASs in commercial products.

Screening of PFAS in aqueous film forming foam for binding to human serum albumin and characterization of mechanisms

2019 Fall National Meeting

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