April 16, 2018

Geosyntec Staff Author Article on Modeling Avian Exposures to Perfluoroalkyl Substances in Chemosphere

Emily Larson (Colorado), Jason Conder (California), and Jennifer Arblaster (Vermont) co-authored an article entitled "Modeling avian exposures to perfluoroalkyl substances in aquatic habitats impacted by historical aqueous film forming foam releases" published in Chemosphere, Volume 201, pages 335-341, in March 2018.

The article addresses the potential ecological risks of perfluoroalkyl and polyfluoroalkyl substances (PFAS) to aquatic-dependent birds. Their work consisted of aquatic food web and wildlife exposure modeling to evaluate the potential for risks to birds associated with five hypothetical site scenarios containing aqueous film-forming foams (AFFF). Site scenarios were based on real-world data. The results of the study can be useful to risk assessors and other stakeholders currently evaluating the hundreds of AFFF sites in the United States and worldwide, and the results may also be useful to the PFAS research community in prioritizing key research goals to understand the ecological risks of PFAS.

Emily Larson is a Scientist based in Colorado focused on modeling the bioaccumulation of semivolatile compounds and metals in ecological systems, modeling exposure to human and ecological receptors, and preparing human health and ecological risk assessments. She also has environmental field experience including sampling soil, surface water, groundwater, and vegetation; and has participated in a multi-year fish population study. Emily has experience with Superfund (CERCLA) as well as several state-led programs specifically in the Intermountain West and Pacific Northwest regions. She has assisted clients in the private sector and in the state and federal public sectors. Emily has provided support on projects evaluating the risks associated with dibenzo-p-dioxin (dioxin) and dibenzofuran (furan) in soil, sediments, and surface water. Her work included developing dioxin-furan congener profiles to identify potential contaminant sources. Emily's current research focuses on evaluating avian exposure through an ecological risk model to seven prominent perfluorinated compounds using data from five aqueous film forming foam (AFFF) sites.

Jason Conder is a Senior Scientist based in California focused on risk assessment and contaminated sediments in contaminated site assessment and management, environmental toxicology, and ecological and human health risk assessment.

Jennifer Arblaster is a Scientist based in California focused on bioaccumulation modeling, ecological and human health risk assessment, dredged material characterization, and evaluation of environmental quality criteria. She has supported multinational clients addressing environmental liability and risk issues associated with a variety of contaminated sites, including several large, multi-stakeholder contaminated sediment sites in North America and Europe, as well as several contaminated industrial sites in California. Jennifer has also contributed to several dredged material assessments for ports and harbors in the United States and Asia. In addition to her general skills in environmental investigation, analysis, and risk assessment, she has specialized experience in fugacity-based food web bioaccumulation modeling for water and sediment quality assessments, database management in Environmental Quality Information Systems (EQuIS), and Monte Carlo Simulation techniques for environmental modeling.

Chemosphere is an international journal designed for the publication of original communications and review articles. As a multidisciplinary journal, Chemosphere offers broad and impactful dissemination of investigations related to all aspects of environmental science and engineering.

Abstract

Releases of Perfluoroalkyl and Polyfluoroalkyl Substances (PFASs) associated with Aqueous Film Forming Foams (AFFFs) have the potential to impact on-site and downgradient aquatic habitats. Dietary exposures of aquatic-dependent birds were modeled for seven PFASs (PFHxA, PFOA, PFNA, PFDA, PFHxS, PFOS, and PFDS) using five different scenarios based on measurements of PFASs obtained from five investigations of sites historically-impacted by AFFF. Exposure modeling was conducted for four avian receptors representing various avian feeding guilds: lesser scaup (Aythya affinis), spotted sandpiper (Actitis macularia), great blue heron (Ardea herodias), and osprey (Pandion haliaetus). For the receptor predicted to receive the highest PFAS exposure (spotted sandpiper), model-predicted exposure to PFOS exceeded a laboratory-based, No Observed Adverse Effect Level exposure benchmark in three of the five model scenarios, confirming that risks to aquatic-dependent avian wildlife should be considered for investigations of historic AFFF releases. Perfluoroalkyl sulfonic acids (PFHxS, PFOS, and PFDS) represented 94% (on average) of total PFAS exposures due to their prevalence in historical AFFF formulations, and increased bioaccumulation in aquatic prey items and partitioning to aquatic sediment relative to perfluoroalkyl carboxylic acids. Sediment-associated PFASs (rather than water-associated PFASs) were the source of the highest predicted PFAS exposures, and are likely to be very important for understanding and managing AFFF site-specific ecological risks. Additional considerations for research needs and site-specific ecological risk assessments are discussed with the goal of optimizing ecological risk-based decision making at AFFF sites and prioritizing research needs.