Approach for Assessing PFAS Risk to Threatened and Endangered Species
Dr. Craig Divine | ARCADIS-US, Inc.
Contamination of soils and waters by per- and polyfluoroalkyl substances (PFASs) has become a widespread problem, especially at Department of Defense (DoD) installations where use of aqueous film forming foam (AFFF) was common. Evaluating chemical risks to threatened and endangered (T&E) species associated with AFFF use is a required component for Superfund ecological risk assessments, however, there is little information on the uptake and toxicity of PFASs to these receptors. The goal of this project is to develop an approach and tools (i.e., risk-based screening levels [RBSLs]) for assessing PFAS risk to T&E species, considering the known fate and transport of these chemicals and the receptors most likely to be impacted at DoD sites. The results will be summarized in a white paper and will consider common T&E species at AFFF-impacted sites, suitable surrogate (non-T&E species) receptors, associated exposure and toxicity assumptions for PFASs, and RBSLs for several PFASs and various environmental media.
The project objective is to develop a comprehensive risk-based approach for evaluating potential ecological impacts on T&E species associated with AFFF use at military installations. Standard risk assessment approaches, as are applied in the United States and internationally, will be used to develop risk-based screening criteria for PFASs. Ecological receptors, including representative T&E species and surrogate receptors, will be selected based on consideration of PFAS-specific risk factors (e.g., biomagnification and trophic level exposures, and species-specific toxicity). Ecological receptors representative of different habitat types, feeding guilds, and trophic levels will be grouped together for classification and risk assessment purposes. Species-specific factors will be compiled from existing databases as well as primary literature. Uptake and toxicity data from the literature will be evaluated with respect to reliability, and high-quality studies will be used as the basis for recommended exposure and effects assumptions for terrestrial and aquatic receptors. For uptake, empirical data will be used to recommend bioaccumulation, bioconcentration, and biomagnification factors for relevant environmental media and trophic levels. Published toxicity benchmarks as well as raw toxicity data will be considered during development of toxicity values. Media-specific risk-based screening levels will then be developed for each receptor and PFAS. For PFASs lacking adequate data to develop a compound specific RBSL, RBSLs based on surrogate compounds or classes of compounds will be considered.
Due to the widespread use of AFFF at DoD installations and potential for offsite migration, rapid and cost-effective methods are needed to evaluate potential ecological risk. The RBSLs can be used to reduce/eliminate the need for site-specific baseline risk assessments and biological sampling. RBSLs provided for individual receptors and PFASs allow for optimization of risk screening based on site characteristics at individual DoD facilities. The overall trends in receptor sensitivity can also be useful to focus preventive measures at DoD installations where highly exposed T&E species may be present. The RBSLs will be in a readily revisable format as additional uptake and toxicity data become available. The development of a strategic approach for addressing potential risk to T&E species that could be applied to all DoD facilities would result in significant efficiencies and cost savings over the course of time. (Anticipated Completion - March 2019)