Per- and Polyfluoroalkyl Substances (PFAS) in Aquatic Environments: Occurrence, Bioaccumulation, and Risk

Abstract

PFAS have become a prominent class of contaminants to study in aquatic environments due to the combination of persistence, mobility, bioaccumulation potential and analytical complexity. This is a narrative review that summarises the peer-reviewed evidence of PFAS presence, sources, bioaccumulation and risk in freshwater systems, estuarine systems and marine systems. The literature demonstrates that a combination of direct industrial discharges, wastewater treatment plant discharges, landfill leachate, aqueous foams which form films, diffuse urban runoff, biosolid-amended catchments and atmospheric deposition drive aquatic pollution. Long-chain perfluoroalkyl acids, especially PFOS and longer-chain perfluorocarboxylic acids, continue to be the focus of bioaccumulation and trophic-transfer issues, whereas short-chain and replacement PFAS have other issues due to their higher mobility and difficulty to eliminate in water. The behaviour of PFAS in aquatic food webs has been shown to be inexplicable in terms of the traditional hydrophobic-partitioning assumptions; protein binding, chain length, functional group, precursor conversion and routes of exposure peculiar to the matrix are all essential. Uncertainty exists in risk assessment due to the predominance of a small number of target analytes in environmental monitoring, disproportionate toxicity data among species and life stages, and inability to resolve mixture effects. The review suggests that the future assessment of aquatic PFAS needs to change its compound-by-compound monitoring to class-conscious, source-conscious, and effects-linked management.