Per- and polyfluoroalkyl substances (PFAS) have been used globally and by the Department of Defense (DoD) for several decades to the extent that they have become ubiquitous in the environment. PFAS are persistent in the environment, which can lead to bioaccumulation and biomagnification of these substances in terrestrial systems. Research on bioaccumulation and biomagnification pathways from soils to higher trophic levels for PFAS was identified as a clear and immediate information gap among the critical priority research needs by the Tri-Service Environmental Risk Assessment Work Group (TSERAWG) and the U.S. Environmental Protection Agency (USEPA). The main objective of this project is to develop empirical data for the uptake and elimination kinetics of PFAS in terrestrial organisms at different trophic levels in order to determine food-web biomagnification potentials for the common PFAS, including those that demonstrated greatest biomagnification risks. 

This project is assessing the uptake, accumulation and elimination kinetics and potential biomagnification of PFAS in terrestrial systems.

The project will investigate the uptake and bioaccumulation of PFAS at different trophic levels in two key terrestrial trophic-chains:

1. soil → terrestrial plant → herbivore mammal
2. soil → soil invertebrate → predatory amphibian

Studies will be conducted with ecologically relevant species using a natural soil that supports high bioavailability of PFAS. The uptake, accumulation and elimination kinetics, and biomagnification of PFAS in the food-web organisms will be assessed using PFAS mixtures in order to assess the potential impacts of competitive uptake and selective bioaccumulation of PFAS. Our goal will be to determine biomagnification of PFAS in terrestrial food-webs from lower trophic level organisms (primary consumers) to higher trophic level organisms (secondary consumers) using environmentally relevant mixtures by addressing the following technical objectives:

1. Determine the uptake of PFAS in terrestrial plants from soil with high bioavailability characteristics (low clay and soil organic matter contents) for PFAS and generate bioconcentration and translocation factors (BCF and TF);
2. Investigate the toxicokinetics of PFAS in soil invertebrates (earthworms) using soil with high PFAS bioavailability characteristics to determine the rates of uptake, elimination, and the bioaccumulation factors (BAF) under realistic exposure conditions, and to generate toxicokinetics data using aqueous exposures to evaluate the relative contributions of dermal and dietary uptake routes;
3. Determine biomagnification factors (BMF) for the chemical transfer of individual PFAS from terrestrial plants to mammals, characterizing and using plants grown in soil amended with PFAS and then by quantifying tissue concentrations and key toxicological responses in Hartley guinea pigs exposed to PFAS through their daily diet; and
4. Determine BMF for chemical transfer of individual PFAS from soil invertebrates to amphibians, characterizing and using earthworms exposed in soil amended with PFAS and then by quantifying tissue concentrations and key toxicological responses in American toads exposed to PFAS through their daily diet.

Ecotoxicological data developed in this project will fill the knowledge gaps regarding biomagnification potential for PFAS released into the terrestrial environment. These data will be used to develop individual BCF, BAF, and BMF values for PFAS in terrestrial systems. These values are needed to quantify the risks for food-web transfer of PFAS to higher-trophic-level receptors, and can minimize future costs for site characterizations and cleanups. Ecotoxicological data, BCF, BAF, and BMF values for PFAS developed in this project will be transitioned to Army/Navy/Air Force through the TSERAWG, directly to USEPA, and to other concerned parties through research presentations and papers. (Anticipated Project Completion - 2023)