The objective of this project is to develop a quantitative understanding of per- and polyfluoroalkyl substance (PFAS) mixture uptake and integrated organismal effects in fish, via simplified laboratory mixtures and an impacted hydrological gradient at Joint Base Cape Cod, Massachusetts. A holistic and transferable field-laboratory modeling approach will be used to address four specific research objectives:

1. PFAS Bioconcentration - determine mixture-specific or concentration-dependent interactions mediating PFAS bioconcentration.
2. Integrated Effects Assessment - characterize multi-omic, cellular, organismal, and population-level biomarker responses to complex environmental mixtures.
3. High-throughput Screening - identify and model effects of PFAS exposures, including those of mixtures.
4. Risk Assessment - develop a novel (eco)toxicity risk-ranking tool to prioritize chemicals and mixtures with the greatest contributions to adverse organismal effects in support of ecological and human health.

To assess PFAS bioconcentration, fish will be exposed to complex mixtures using flow-through, mobile exposure laboratories. Uptake of PFAS will be evaluated relative to physicochemical predictions to determine site-specific or concentration-dependent interactions. Biomarker responses to complex environmental mixtures will be evaluated through multi-omic molecular, cellular, organismal, and population (i.e. fecundity) levels (i.e., using a systems approach) to determine response thresholds, dose-dependency, and mode of action. The relationship between biomarker response and PFAS body burden will be evaluated by individual chemical. High-throughput exposure experiments using zebrafish and fathead minnows will determine the extent to which safety factors underlying advisory levels for priority PFAS (i.e., perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA)) adequately incorporate risk from site-specific, co-occurring chemicals. Finally, overall PFAS intel and risk-ranking outcomes from these field and laboratory PFAS mixture studies will be used to assess database-derived comparative ecotoxicity for environmental risk assessment of PFAS mixtures.

The DoD faces enormous challenges to address the long-term impacts and remediation of persistent PFAS plumes that often are mixed with other recalcitrant co-occurring chemicals. Data on the environmental risk of PFAS associated with aqueous film-forming foams (AFFFs) and other sources will assist in the development of appropriate site-specific risk assessments and other decisions related to mitigation of exposures and/or future environmental cleanup. This project will inform approaches and tools for environmental monitoring of PFAS-impacted sites by a) identifying PFAS environmental mixture concentration ranges linked to measured biomarker responses, b) determining the extent to which laboratory-derived PFAS benchmark doses are protective of fish health under scenarios of exposure to sites impacted by PFAS mixtures and other co-occurring chemicals, c) validating high-throughput screening assessments for identifying hazards to ecological receptors, and d) determining the extent to which adverse organismal outcomes can be predicted by aquatic PFAS concentrations or PFAS body burden. The integrated field and laboratory approach is transferable to other DoD projects and other PFAS-impacted sites. (Anticipated Project Completion - 2025)