SETAC Europe 35th Annual Meeting

Application of Chemical Activity in Environmental Risk Assessment Using a Rapid Equilibrating Sampler: A Case Study on Perfluorooctane Sulfonate (PFOS)

Abstract: Current approaches for evaluating risks of contaminant exposure to human health and ecological receptors rely on the comparison of exposure and toxicological effect or no-effect concentrations. A key limitation of this approach is the inherent difficulty of comparing substances across different environmental media. Additionally, these methods are often restricted to one-to-one comparisons between exposure and effects concentrations in a single medium such as water or sediment. Consequently, much available information for risk assessments is not used. In this study, we explore the application of a chemical activity-based approach to facilitate the comparison of concentrations of PFAS among different environmental media and enhance the risk assessment process. Chemical activity is a thermodynamic quantity that describes the “effective concentration” for a substance in a sample, accounting for factors such as chemical’s interaction with the media, temperature, and pressure. As such, chemical activity provides a way to better describe chemical partitioning, bioaccumulation, and toxic modes of action. It also enables the direct comparison of concentrations of a substance in different media. This study focuses on the application of activity on the behaviour and toxicity of perfluorooctane sulfonate (PFOS). A rapid-equilibrating thin-film passive sampler was developed and calibrated with a wide range of concentrations of PFOS in water and buffered saline. The thin-film sampler was subsequently used as a proxy to estimate the chemical activity of PFOS in samples. Results show a distinct relationship between the concentration measured in the thin-film and the activity of PFOS in the incubation solution at environmentally relevant concentrations. The thin-film sampler also effectively estimates the concentration, sorptive capacity, as well as partition coefficients for PFOS in serum albumin. Overall, we illustrate the measurement of chemical activity through rapid equilibration and demonstrate its potential as an integrative tool for supporting more comprehensive and effective environmental risk assessments.

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Author(s):

Sophia S.H. Hsu Simon Fraser University, Azimuth Consulting Group Canada This Author Is the Presenter

Frank Gobas Simon Fraser University Canada

Barry Kelly Simon Fraser University Canada