Sand dollars (Mellita quinquiesperforata): A new bioindicator for tracking PFAS in coastal waters

Sand dollars are unique environmental monitoring indicators in that they are benthic burrowers in coastal habitats, and as primary consumers, they have the ability to bioaccumulate pollutants from the sediment. In this study, we examined per- and polyfluoroalkyl substances (PFAS) in sand dollars (Mellita quinquiesperforata) at six sites within Tampa Bay, Florida (USA). Overall, 13 PFAS were detected in at least one sand dollar, with the top-3 mean concentrations: perfluorooctanesulfonic acid (5.29 ng/g, dry weight), perfluorobutanoic acid (3.72 ng/g), and perfluorohexanesulfonic acid (2.46 ng/g). Of note, perfluoroalkyl carboxylic acids (PFCA) concentrations decreased with chain length while perfluoroalkyl sulfonic acids (PFSA) concentrations increased with chain length, and on average, the Σ₁₃PFAS was comprised of 68 % PFSAs. Short chain PFAS were among those that showed the greatest potential to bioaccumulate in the sand dollars. Overall, these data suggest that sand dollars are suitable as indicators for assessing PFAS-sediment pollution in benthic environments.