Per- and polyfluoroalkyl substances (PFASs) 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. PFASs 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 PFASs 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 PFASs in terrestrial organisms at different trophic levels in order to determine food-web biomagnification potentials for the common PFASs, including those that demonstrated greatest biomagnification risks.
The project will investigate the uptake and bioaccumulation of PFASs at different trophic levels in two key terrestrial trophic-chains:
- soil → terrestrial plant → herbivore mammal
- soil → soil invertebrate → predatory amphibian
Studies will be conducted with ecologically relevant species using a natural soil that supports high bioavailability of PFASs. The uptake, accumulation and elimination kinetics, and biomagnification of PFASs 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 PFASs. Our goal will be to determine biomagnification of PFASs 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:
- Determine the uptake of PFASs in terrestrial plants from soil with high bioavailability characteristics (low clay and soil organic matter contents) for PFASs and generate bioconcentration and translocation factors (BCF and TF);
- Investigate the toxicokinetics of PFASs 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;
- Determine biomagnification factors (BMF) for the chemical transfer of individual PFASs from terrestrial plants to mammals, characterizing and using plants grown in soil amended with PFASs and then by quantifying tissue concentrations and key toxicological responses in Hartley guinea pigs exposed to PFASs through their daily diet; and
- Determine BMF for chemical transfer of individual PFASs from soil invertebrates to amphibians, characterizing and using earthworms exposed in soil amended with PFASs and then by quantifying tissue concentrations and key toxicological responses in American toads exposed to PFASs through their daily diet.
Ecotoxicological data developed in the this project will fill the knowledge gaps regarding biomagnification potential for PFASs released into the terrestrial environment. These data will be used to develop individual BCF, BAF, and BMF values for PFASs in terrestrial systems. These values are needed to quantify the risks for food-web transfer of PFASs to higher-trophic-level receptors, and can minimize future costs for site characterizations and cleanups. Ecotoxicological data, BCF, BAF, and BMF values for PFASs 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)