Little is understood about the impacts of exposure to per- and polyfluoroalkyl substance (PFAS) mixtures, but their ubiquitous presence in soil and water at and around military installations with current and historical use of PFAS-containing aqueous film-forming foam (AFFF) is an environmental and health safety concern. In this project, a One Health approach will be utilized to assess how exposure to individual PFAS and PFAS mixtures partition into different biological compartments (e.g., into the serum or tissues), travel up the food chain (e.g., from mice to raptors), and affect development in a keystone species. The objectives of this project are to understand the dynamics of whole-body burden and serum concentrations of individual PFAS and PFAS mixtures in mice and the effects of PFAS trophic transfer in the American kestrel, an avian species that consumes rodents and is found on military sites throughout the country. These data are needed for environmental remediation prioritization and ecological risk assessments and will establish a framework for understanding if PFAS mixtures behave differently than individual PFAS.

Mus musculus will be exposed via oral gavage to individual PFAS or PFAS mixtures and assessed for whole-body burden and serum PFAS concentrations. Results for the mixtures will be compared to the individual PFAS exposure results for identification of mixture influence on PFAS retention and/or elimination patterns. American kestrel pairs will be dosed with a PFAS mixture in their diet at a concentration based on the PFAS whole-body burden data collected from the mice. The birds will then be allowed to mate and lay eggs. A subset of eggs will be assessed to evaluate PFAS transfer. The remaining eggs will be incubated naturally to determine effects on hatch rate. Hatchlings will be orally dosed with the PFAS mixture and allowed to fledge. Fledgling serum and tissue samples will be analyzed for PFAS concentrations, and plasma will be analyzed for immune and thyroid indicators. Exposure-dependent effects observed in the mice, eggs, and fledglings will be modeled at their individual trophic levels and within a community interaction model to understand potential population-level effects.

In support of the Defense Centers for Public Health - Aberdeen (DCPH-A) mission, this project addresses the need to understand the toxicity of PFAS mixtures released from AFFF into the environment. This project will collect data across four strata relevant to One Health approaches to chemical management on military lands. First, connecting whole-body PFAS burden with serum PFAS concentrations will improve understanding of sampling accuracy and internal dosimetry. Second, including PFAS individually and as representative mixtures allows for determination of additive, potentiated, synergistic, or antagonistic effects. Third, connecting adult PFAS mixture exposure with egg deposition and developmental effects in offspring will provide key information on vertical transfer of PFAS in a raptor found at military sites throughout the United States. Fourth, collecting data from species across trophic levels will allow the modeling of population- and community-level effects of exposure to PFAS mixtures. This collaborative project between the DCPH-A and the U.S. Geological Survey will explore the effects of exposure to environmentally relevant PFAS mixtures on wildlife in support of future ecological risk assessments and environmental remediation prioritization. (Anticipated Project Completion - 2027)