August 13, 2019

Jason Conder and Jennifer Arblaster to Present at Society of Environmental Toxicology and Chemistry (SETAC) PFAS Meeting

Jason Conder, Ph.D. (California) and Jennifer Arblaster (Vermont) will present on risk assessments associated with per- and polyfluoroalkyl substances (PFAS) at the Society of Environmental Toxicology and Chemistry (SETAC) North America Focused Topic Meeting on "Environmental Risk Assessment of PFAS" at the Durham Convention Center in Durham, North Carolina from August 12-15, 2019.

Jason will present "Classification and Grouping of PFAS for Environmental Risk Assessment." He and Jessica will present posters entitled "Guidance for Assessing the Ecological Risks of Threatened and Endangered Species at Aqueous Film Forming Foam (AFFF)-Impacted Sites" and "Framework for Assessing Risks to Threatened and Endangered Aquatic Life at PFAS Impacted Sites," respectively, highlighting the "Guidance for Ecological Risk Assessment of PFAS" that they  developed for the Department of Defense under the Strategic Environmental Research and Development Program (SERDP).

Jason is a Principal Scientist with more than 10 years of experience focused on risk assessment and contaminated sediments in contaminated site assessment and management, environmental toxicology, and ecological and human health risk assessment. He has advised numerous large, multi-stakeholder client and client groups at contaminated sediment and uplands sites in North America, Europe, and Asia on matters relating to chemical fate, risk assessment, remediation, and chemical liability.

Jennifer has more than eight years of experience in bioaccumulation modeling and ecological and human health risk assessment. She was one of the primary contributors to "State-of-the-Science Report: Perfluoroalkyl and Polyfluoroalkyl Substances," a detailed and comprehensive state-of-the-science review of PFAS that included a detailed review of historical and current sources, products and uses, environmental fate and transport, toxicity, considerations for site investigations and conceptual site model development for PFAS-impacted sites, and recent developments in alternative technologies.

This SETAC North America Focused Topic Meeting will synthesize recent advances in chemistry, environmental fate and exposure, human and ecological toxicity, and risk characterization of PFAS. The objectives of the meeting are to review new and emerging information on PFAS and to formulate a roadmap for a risk assessment approach for PFAS.

SETAC promotes the advancement of environmental sciences, education in the field, and the use of science in environmental policy- and decision-making. The society provides a forum where environmental professionals exchange information and ideas for the development and use of multidisciplinary scientific principles and practices leading to sustainable environmental quality. SETAC achieves this through events, publications, education, and certification programs.


Presentation Title: Classification and Grouping of PFAS for Environmental Risk Assessment
Time: 12:00-12:20 p.m. on August 12, 2019
J.M. Conder, J. Arblaster, E. Larson, Geosyntec Consultants
Abstract: Per- and polyfluoroalkyl substances (PFAS) comprise several thousand different compounds that span an incredibly wide range of exposure and hazard profiles. This presentation will provide an overview of the major PFAS groupings and highlight some of the key exposure scenarios that have received attention with regards to risk-based decision-making. Key to this review are the extremely large differences in fate, exposure, and potencies among the PFAS groups. A key focus of this presentation will include a case study on the assessment and management of key perfluoroalkyl acids (PFAAs) and other PFAS associated with site-specific releases of aqueous film-forming foam (AFFF) used in the fighting of Class B hydrocarbon fires. The wide variety of exposures and risks among the various PFAS associated with AFFF risks illustrates the extreme diversity of the various PFAS groups in terms of their exposure and effect potential. With regards to understanding risk, PFAS are not a monolith, and there are currently no shortcuts or easy answers.

Poster Title: An Approach for Developing Risk-Based Screening Criteria for Consumption of Food Crops Impacted by Poly and Perfluoroalkyl Substances
J.B. Brown, C.P. Higgins, Colorado School of Mines; J.M. Conder, J. Arblaster, Geosyntec Consultants
Abstract: Per- and polyfluoroalkyl substances (PFAS) have been identified as chemicals of concern in agricultural soils, biosolids-amended soil, and irrigation water due to their toxicity, persistence, bioaccumulation potential and occurrence in these media. The agricultural use of PFAS-contaminated water, municipal and industrial biosolids, and municipal compost can all contribute to the exposure of food crops to PFAS. Irrigation water containing variable levels of PFASs may contaminate soil over time resulting in additional exposure pathways to food crops. The uptake and accumulation of PFAS in food crops is an important and continuing concern for protecting human health. There is an urgent need for regulatory agencies to assess the accumulation of PFAS in the edible portion of food crops as consumers often eat these foods fresh or with minimal processing. Recognition of PFAS in food as a potentially important contributor to human exposure, as well as the identification of PFAS-impacted irrigation water and soils in areas with agricultural activities, has resulted in several studies on the uptake of PFAS into crops. Using available crop-specific transfer factors (TFs) from lettuce bioaccumulation studies, exposure data, and consumption rates for homegrown produce, exposure intakes are estimated for a range of concentrations for different population subgroups using Monte Carlo Simulation in a tiered stochastic modeling approach. For PFASs with oral toxicity reference doses, risk-based concentrations (RBCs) for selected PFAS in contaminated soil and irrigation water were determined for adults and children. The RBCs are compared to available health advisories or criteria and the influence of other exposure pathways is evaluated. Lastly, we explore the utility and challenges of implementing a relative potency factor approach to assess risk from a mixture of PFAS. Prediction outcomes from a hypothetical farm illustrate the model application to a real-world scenario.

Poster Title: Guidance for Assessing the Ecological Risks of Threatened and Endangered Species at Aqueous Film Forming Foam (AFFF)-Impacted Sites
J.M. Conder, E. Larson, J. Arblaster, Geosyntec Consultants; J.B. Brown, C.P. Higgins, Colorado School of Mines
Abstract: Per- and polyfluoroalkyl substances (PFAS) have been widely used in numerous applications since the 1950s, including aqueous film forming foams (AFFFs) used for fire suppression at airports, firefighting training facilities, and other industrial locations. PFASs are routinely detected in a wide variety of environmental media impacted by AFFF, and have prompted regulatory focus on exposures and risks. Many AFFF sites host ecological habitat or, due to the offsite transport potential for PFASs, PFAS-impacted AFFF sites may affect nearby and downgradient habitats. As part of a Strategic Environmental Research and Development Program project, a guidance document was developed to provide a current state-of-the-practice overview of methods, practices, and key data gaps for assessing the potential for risks from exposure to PFAS for threatened and endangered (T&E) species at AFFF-impacted sites. The guidance is intended to provide clear guidance to quantitatively evaluate ecological risks and enable site managers to make defensible, risk-based management decisions using the best available information and approaches. The key objectives are: 1) to provide a framework for the evaluation of T&E species during ecological risk assessments (ERAs) at AFFF-impacted sites; 2) to provide the reader with an understanding of the specific T&E species or general feeding guilds typically expected to be considered most at risk at AFFF-impacted DoD sites; 3) to provide the reader with recommended parameters (exposure factors, toxicity reference values [TRVs], uptake factors) to perform a food web model-based ERA for wildlife T&E species; and 5) to provide the reader with an understanding of key data gaps and uncertainties when evaluating T&E species at AFFF-impacted sites. Several hundred toxicity values and over 1000 bioaccumulation parameters were assessed in the guidance review effort, resulting in 150 recommended values for use in ERAs. In addition to providing a review of the available literature and recommendations for ERA parameters, the guidance reaches the following key conclusions: 1) ERAs for AFFF sites are feasible; 2) off-site habitats are most at risk; 3) aquatic habitats are critical to address; 4) terrestrial habitats may be important at some sites; 5) risks from mixtures is uncertain; and 6) the exposures and effects of many PFAS-constituents in AFFF are unknown.

Poster Title: Framework for Assessing Risks to Threatened and Endangered Aquatic Life at PFAS Impacted Sites
J. Arblaster, J.M. Conder, E. Larson, Geosyntec Consultants; J.B. Brown, C.P. Higgins, Colorado School of Mines
Abstract: The United States Department of Defense is one of the primary stewards of Threatened and Endangered (T&E) species on Federal lands. As part of a Strategic Environmental Research and Development Program project, guidance on the current methods for assessing risks to T&E aquatic life from exposure to per and polyfluoroalkyl substances (PFAS) was developed. To evaluate risks to aquatic T&E species, over 50 laboratory aquatic toxicity studies on PFAS were reviewed. To reflect a high level of conservatism for T&E species, no observed effect concentrations (NOEC) or 10% effective concentrations (EC10) were compiled for U.S. resident species and reviewed for inclusion in a Species Sensitivity Distribution (SSD) for PFOS and PFOA (no other PFAS met minimum data requirements for SSDs). A total of 82 NOECs for freshwater aquatic species and 14 NOECs for marine aquatic species were included in SSDs for PFOS and PFOA. One percent and five percent hazardous concentrations (HC1 and HC5) were calculated from the SSD following USEPA guidance. HC1 values for PFOS were 0.56 ug/L and 2.57 ug/L for freshwater and marine species, respectively. HC5 values for PFOS were 5.8 and 7.7 ug/L for freshwater and marine species, respectively. The HC1 and HC5 value for PFOA were 537 ug/L and 1,110 ug/L for freshwater species, respectively (data were insufficient for marine species). HC5 values are typically accepted as protective thresholds for aquatic life. Based on the inclusion of NOEC values as the basis for the SSD, the HC5 values reported here are expected to represent conservative thresholds for evaluating risks to aquatic T&E species and aquatic life.

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Geosyntec Consultants
Geosyntec is a consulting and engineering firm that works with private and public sector clients to address new ventures and complex problems involving our environment, natural resources, and civil infrastructure.

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