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Presentation Slides

This SERDP and ESTCP webinar focuses on DoD-funded research efforts to assess ecological PFAS exposure and effects. Specifically, investigators will discuss the results of a multi-generational zebrafish exposure-response study to better derive PFOS risk estimates and reliance on tree swallows as indicators of PFAS exposure and effects at selected DoD sites. 


 “Results from a Multi-Generational Zebrafish PFOS Exposure-Response Study” by Dr. David Moore (SERDP Project ER20-1542

The Environmental Protection Authority (EPA) of Victoria, Australia, released water quality guidelines in 2016 for PFOS that included a freshwater 99% species protection level of 0.00023 μg/L, a value more than 100 to 1,000 times lower than screening values put forth by other regulatory agencies. Derivation of this low threshold was driven largely, if not almost entirely, by results from a single study published in 2012 which involved a multi-generational exposure of the zebrafish (Danio rerio) to PFOS and reported reduced growth at 0.6 μg/L. Despite the limitations of the study design (e.g., low replication, small and unevenly spaced exposure range, and limited exposure verification), the reported result appears to have had a significant influence on the Australian guidance and has the potential to influence future regulatory threshold values. Consequently, the U.S. Army Engineer Research and Development Center (ERDC), in collaboration with the U.S. EPA and with financial support from SERDP and a coalition of businesses, conducted a multi-generational study of the effects of low-level PFOS exposure on zebrafish using a more robust experimental design and an expanded suite of test endpoints. Based on results from this study involving 180-day exposures of both the parental and first familial generations, the strongest evidence of potential ecologically significant effects on zebrafish occurred at the 100 μg/L exposure concentration (i.e., the highest level evaluated), which showed potential effects on survival and growth, but no effects on reproduction. This webinar will provide the details of this study, including methodology and analyses, which resulted in an improved basis for derivation of PFOS risk estimates moving forward. 

“Tree Swallows as Indicators of PFAS Exposure and Effects at Selected DoD Sites in the Mid-Atlantic Region, USA” by Dr. Christine Custer (SERDP Project ER21-3464

While exposure of wildlife to PFAS can come from many sources, one prominent source is AFFF (aqueous film-forming foam) when used operationally and for training. The objective of this study is to use a model avian species, the tree swallow (Tachycineta bicolor), to assess exposure to and quantify the effects of PFAS at DoD sites in the mid-Atlantic region compared to a nearby reference location and to sites with other PFAS sources. Tree swallow nest boxes were erected and sampled at selected installations (Joint Bases Willow Grove and McGuire-Dix-Lakehurst; Naval Research Lab, Chesapeake Bay; and two locations at the Patuxent Research Refuge [the reference location]) in 2020, 2021, and 2022. Tree swallow nesting was monitored weekly and egg, nestling, and diet samples were collected at specific times in the nesting cycle. Samples were analyzed for 40 PFAS and also biomarker responses. Two levels of effects were assessed relative to PFAS and other contaminant exposures. At the population level, precent hatching and daily probability of nest success were assessed to determine reproductive effects. Biomarker responses, which are indicative of whether exposure is enough to elicit a physiological response in individual birds, was compared to normal responses (Patuxent reference swallows) and assessed relative to PFAS exposure. This presentation will present preliminary results of this study. Different levels of PFAS exposure and differences in the relative concentrations of specific PFAS were observed across study sites. These differences will allow for a robust assessment of which PFAS are contributing to effects, if observed.

Speaker Biographies

Dr. David Moore is a senior research biologist with the U.S. Army Engineer Research and Development Center (ERDC) in Vicksburg, Mississippi. He currently leads ERDC’s program on Advanced Materials and Substances of Emerging Environmental Concern (AMSEEC). Drawing on over 35 years of experience, Dr. Moore has served as principal or co-principal investigator on projects funded by SERDP, Office of the Secretary of Defense, the U.S. Navy, and numerous industrial sponsors on topics relating to PFAS, AFFF replacement products, and the application of novel modeling approaches for risk characterization of PFAS. He has authored over 40 peer reviewed publications. Dr. Moore received a bachelor’s degree in biology from Washington and Lee University and a doctoral degree in environmental toxicology from the University of South Carolina.  

Dr. Christine Custer is a research wildlife biologist at the United States Geological Survey’s Upper Midwest Environmental Sciences Center. Since the 1970’s, Dr. Custer’s research has focused on the effects of contaminants on avian populations. The contaminants of concern she has studied have shifted over the decades and have ranged from legacy organics, DDE, PCBs, and dioxins and furans to other classes such as trace elements, polycyclic aromatic hydrocarbons, and now PFAS. Species she has focused on in her studies have also varied, depending on the geographic location, food web of concern, and other factors. Her most recent work centers on PFAS effects on tree swallows.