The overall goal of this project is to evaluate the ability of biomimetic chromatography and tissue fractionation measurements to provide a mechanistic understanding of per- and polyfluoroalkyl substances (PFAS) bioaccumulation. In turn, these values could be applied to PFAS risk assessment, especially for the dozens to hundreds of PFAS for which empirical PFAS bioaccumulation metrics are currently unavailable. If successful, these research techniques have the capability to save money and time conducting research; reduce uncertainty with current site investigations and new firefighting foams; and advance a new paradigm for understanding the biological behavior of PFAS. Below are the five project objectives:

1. To experimentally measure physiologically relevant partition coefficients of target, suspect, and nontarget PFAS and other AFFF-related components.
2. To model species and tissue differences in protein-water and membrane-water interactions.
3. To develop machine learning tools that guide selection and prioritization of PFAS.
4. To fractionate fish tissues to identify biological phase(s) responsible for PFAS uptake.
5. To correlate partition coefficients with field-observed bioaccumulation metrics.
6. To communicate results of this research to stakeholders inside and outside the DoD.

The ultimate goal of the biomimetic and tissue fractionation chromatography approaches is to improve the understanding of PFAS bioaccumulation in aquatic food webs. Specifically, the project team envisions they can derive a quantitative algorithm or model that would use biomimetic chromatography measurements and tissue fractionation of PFAS to predict bioaccumulation metrics that can directly be used in PFAS food web models (i.e., water-to-fish bioconcentration factors (BCF), food-to-fish biomagnification factors, water-to-pelagic invertebrate BCF, etc.). These algorithms/models will be developed from a subset of PFAS for which bioaccumulation metrics are widely available. Robust algorithms/models can then be used to predict bioaccumulation metrics for PFAS for which there are no empirical measurements of bioaccumulation in organisms. Together biomimetic chromatography and tissue fractionation (and subsequent bioaccumulation metric predictions) can also be used to further develop a mechanistic understanding of PFAS bioaccumulation that is analogous to mechanistic paradigms for hydrophobic organic compounds, which rely on a compound's octanol-water partition coefficient and organismal lipid contents to predict bioaccumulation.

The expected benefits of this project are to help enable a mechanistic understanding of PFAS bioaccumulation in aquatic food webs. If the approaches are successful, bioaccumulation for less-studied PFAS could be predicted rather than determined empirically via bioaccumulation tests. Bioaccumulation values can be used in site-specific human and ecological assessments, directly addressing uncertainty in PFAS management. This project will also allow prioritization of PFAS that need additional empirical study. Such research will directly improve management of PFAS-impacted sites, thereby ensuring installations remain mission-capable while safeguarding critical defense infrastructure and the workforce. (Anticipated Completion Date - 2027)