This project aims to develop an improved understanding of the marine ecotoxicity of per- and polyfluoroalkyl substances (PFAS) associated with aqueous film forming foam (AFFF) use. This will be done through a series of laboratory toxicity and bioaccumulation experiments with 10 target PFAS, aiming to provide the following critical data to decision-makers and ecological risk assessors evaluating the risks of PFAS exposure at marine sites:

• Reliable and robust toxicity benchmarks for marine aquatic life (pelagic fish, pelagic and benthic invertebrates);
• A quantitative approach for evaluating the adverse effects of PFAS mixtures to aquatic life;
• A quantitative approach for predicting multi-generational aquatic life effects; and
• Uptake factors for evaluating food web (dietary) exposures to aquatic-dependent wildlife (e.g., birds, mammals, and herptiles).

The data gaps filled by the project will enable AFFF-impacted marine sites to move forward with ecological risk assessments (ERAs) within the site investigation process using sound, scientifically supported information.

This project features a comprehensive five-task design based on 163 spiked-PFAS toxicity and bioaccumulation bioassays in water and sediment and more than 1,800 PFAS analyses. The project aims to fill current critical data gaps that impede effective ERAs at marine sites impacted with AFFF by producing the following quantitative data deliverables:

• Single-PFAS Water and Sediment Benchmarks: Risk-based values to enable the evaluation of direct effects on marine pelagic and benthic aquatic life using measurements of PFAS in water and/or sediment. Synchronous tissue analysis will also enable a linkage between tissue PFAS concentrations and toxic effects (i.e., critical body residues);
• PFAS Mixture Approach: A quantitative approach that allows a characterization of PFAS mixture toxicity using measurements in water and/or sediment in a manner similar to other multi-toxicant approaches (e.g., Toxic Unit Approach for polycyclic aromatic hydrocarbons);
• Multi-generation Benchmark Approach: Quantitative values that can be used to predict benchmarks that are protective of multi-generation exposures to aquatic life, using benchmarks developed using traditional toxicity testing (similar to Acute-to-Chronic Ratios used for water quality criteria derivation); and
• PFAS Uptake Factors: Bioconcentration factors and biota-sediment accumulation factors that can be used to predict concentrations in key aquatic-dependent wildlife prey items (pelagic invertebrates, benthic invertebrates, and fish), completing the parameterization of bioaccumulation models critical for ERA of PFAS to marine aquatic-dependent wildlife.

The primary expected benefit of this project is to provide risk assessment experts with quantitative information to enable more accurate PFAS ERAs for aquatic life and aquatic-dependent wildlife at AFFF-impacted marine sites. Currently, these critical data gaps are likely to result in excessive and costly remediation approaches based on unnecessarily conservative assumptions of PFAS risks at AFFF-impacted marine sites. The expected data produced by this project – benchmarks for PFAS in sediment and water, a quantitative algorithm for evaluating mixture risks to aquatic life, and uptake factors for predicting concentrations in wildlife diet items – will be directly applicable for site-specific ERAs and associated decision-making. Additionally, this work will address key concerns regarding the need for multigenerational aquatic toxicity evaluation, a key uncertainty related to the stakeholder acceptance of toxicity benchmarks for aquatic life. (Anticipated Project Completion – 2026)