Federal and State threatened and endangered fauna species occupy many Department of Defense (DoD) sites. The diversity of the species is great, ranging from invertebrates to higher trophic level predators. Importantly, many DoD sites are also impacted by historical activities that result in chemical impact. One of those activities was widespread use of aqueous film-forming foams to suppress fires and in fire training exercises that has resulted in per- and polyfluoroalkyl substances (PFAS) distributed in many environmental compartments.

The objectives of this project were to: (1) address the information needs concerning the likely co-occurrence of specific threatened and endangered (T&E) species as defined by the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (NMFS) of the National Oceanic and Atmospheric Administration (NOAA) and PFAS impact at DoD installations and (2) develop a tiered approach to quickly and cost-effectively conduct a screening-level assessment of risk or identify important data and modeling needs to reduce uncertainty in assessing risk to T&E species that may be exposed to PFAS on DoD installations.

A species-specific exposure potential to PFAS was developed to provide an initial screen of impacted habitat using spatial analysis. Protected species (or taxa) can then be ranked by those that occupy the greatest proportion of PFAS-impacted habitat. Those species may be prioritized for hazard and/or risk assessment. Here, the project team carried two species (northern pine snake and bald eagle) through to develop a probabilistic risk framework on site specific perfluorooctane sulfonate (PFOS) concentrations.

Investigating three DoD installations generally resulted in high exposure potential for those species that have smaller ranges (invertivores) compared to species that move great distances over the landscape (carnivorous mammals). Furthermore, exposure potential models provide a map that illustrates the overlap of critical habitat with areas of suspected PFAS impact, which is useful for natural resource managers in prioritizing environmental remediation.

Based on results from the spatial exposure potential model and the SERDP statement of need requesting information on species that occupy multiple DoD sites, two species were selected for developing the risk framework; those were the state listed (New Jersey/Tennessee) northern pine snake and the federally protected bald eagle. These species were selected based on high exposure potential, occupancy on multiple installations and no available data on risk of PFAS to these receptors. Currently, there are no published data of PFAS risk to reptiles and importantly, there are many reptilian species that occupy DoD sites. Probabilistic risk frameworks were developed for the northern pine snake and the bald eagle that incorporates species-specific physiology and behavioral traits. Results of the risk model were compared to working Toxicity Reference Values (TRV) for each species. The risk frameworks focused on PFOS alone, as this is currently, the most frequently encountered and believed to be the most hazardous of the PFAS to wildlife.

The probabilistic model indicates the northern pine snake is not likely to be affected even with 100% of dietary items captured from PFOS-impacted habitats (~16 µg PFOS/kg soil) on Joint Base McGuire Dix Lakehurst. Conversely, the bald eagle model that focuses on the eaglet life-stage shows there may be risk resulting from PFOS exposures. Eaglets have small body-size with high energetic demands that drive exposure. Nests in closer proximity to PFAS-impacted water bodies are assumed to receive a greater proportion of PFOS-impacted prey items. With 10% of prey items from an impacted water body, the eaglet model shows the TRV is exceeded regularly over the course of development to fledging (60-days). Although the models are comprehensive, further information on exposure estimates from field research would be useful in refining the probabilistic risk estimates. In addition, given the high exposure potential to invertebrates and invertivores, toxicity data and exposure/risk modeling to these receptors is needed.

This research benefits DoD installations by applying a rapid screening-level approach to determine which wildlife receptors may be at greatest risk of exposure. Given the current limitations on toxicity (or hazard) information, addressing exposure may be a more rapid route to take in determining if wildlife receptors are expected to come into contact with PFAS-impacted habitat. Furthermore, the probabilistic risk framework developed for reptiles and avian predators illustrates an initial path forward in conducting full ecological risk assessments on DoD sites.