Differential Bioaccumulation of Legacy and Novel Per- and Polyfluoroalkyl Substances (PFAS) in Plants and Soil Biota: Implications for Human Exposure and Risk Mitigation

Global restrictions on legacy per- and polyfluoroalkyl substances (PFAS) have resulted in the increased use of replacements including short-chain PFAS and novel alternatives such as ether-PFAS or compounds with F partially substituted by H or Cl. Bioaccumulation of PFAS in soil ecosystems is generally under-investigated but has great ecological safety and human health significance. This review compares the differential behaviors of legacy and novel PFAS in plants and soil-dwelling invertebrates to assess PFAS bioaccumulation and influencing factors in soil ecosystems. The potential effects of PFAS molecular structures and physiological characteristics of biota are discussed. Shortened fluorocarbon chains (e.g., perfluorobutanoic acid, PFBA), ether insertions (e.g., hexafluoropropylene oxide dimer acid, GenX), and H/F substitutions (e.g., 1H,1H,2H,2H-perfluorooctanesulfonic acid, 6:2 FTSA) in novel PFAS increase soil bioavailability and plant translocation from roots to aboveground tissues. Greater CF₂ units and Cl/F substitution (e.g., 6:2 chlorinated polyfluorinated ether sulfonate, 6:2 Cl-PFESA) in novel PFAS contribute to retention in plant roots and accumulation in invertebrate tissues. Based on the bioaccumulation of legacy and novel PFAS, the development of predictive bioaccumulation models, frameworks for human exposure and ecological risk assessment, and options for PFAS contamination management and risk mitigation are discussed and highlighted as research priorities.