Sediment quality assessment framework for per- and polyfluoroalkyl substances: Results from a preparatory study and regulatory implications

Abstract

A preparatory study was performed to develop a sediment quality and risk assessment strategy for Switzerland, addressing the following questions: the sediment fraction to be analyzed chemically (< 63 µm, or alternatively < 2 mm); the suitability of using perfluorooctanesulfonic acid (PFOS) as an indicator of per- and polyfluoroalkyl substances (PFAS) contamination in sediments; the availability of data for the derivation of sediment quality guidelines; and the suitability of normalization to total organic carbon (TOC). The results confirmed PFOS as a suitable indicator of PFAS contamination in sediments from small streams, being the most detected and on average with the highest concentrations among the analyzed PFAS. The fine fraction (< 63 µm) was more appropriate to screening for possible sources and studying the compound profiles at the study sites, but the analysis of the < 2 mm fraction and the normalization to a sample consisting of 100% of the < 63 μm fraction was, in principle, feasible for PFOS. Sediment quality guidelines for PFOS aiming to protect benthic invertebrates from generic adverse effects could be derived, but the available toxicity database is still too sparse. It was only possible to derive preliminary values. Sediment quality guidelines to protect wildlife and human health from secondary poisoning, using the equilibrium partitioning approach and simple trophic web models, were also derived. The use of food web models to derive sediment quality guidelines has not been validated, and the available database of Biota-Sediment Accumulation Factors and Trophic Magnification Factors for PFOS remains limited. However, it is still larger than the effect concentrations database based on sediment studies using benthic invertebrates. Normalization to TOC content in the field (0.2%–12.9%) was decisive in the quality assessment outcome. This is a widely accepted practice for hydrophobic organic contaminants, but its endorsement for PFOS would also benefit from validation. Integr Environ Assess Manag 2021;17:716–725. © 2021 SETAC.