Persistent Organic Pollutants, PFAS and Legacy Contaminants

Persistent organic pollutants (POPs) are halogenated or aromatic carbon compounds that resist environmental degradation and accumulate in the fatty tissues of living organisms, producing concentrations in apex predators and humans that may be orders of magnitude higher than those in the surrounding abiotic environment. They are commonly characterised by persistence (P), bioaccumulation (B), long-range transport (LRT), and toxicity (T). Major classes include legacy organochlorine pesticides such as DDT, dieldrin, chlordane and toxaphene; polychlorinated biphenyls (PCBs); polychlorinated dibenzo-p-dioxins and dibenzofurans; and per- and polyfluoroalkyl substances (PFAS). A literature survey of more than 3,000 publications from 2009 to 2026, with more than 886 papers reported for 2025, indicates that PFAS now dominate research activity in this area, reflecting both the scale of contamination and the urgency of developing effective remediation and regulatory responses. This chapter reviews the chemistry underlying persistence, bioaccumulation and long-range transport; examines the toxicology of the principal POP classes, including emerging evidence on PFAS neurotoxicity, carcinogenicity and prenatal health effects; analyses the evolving PFAS regulatory landscape, including the April 2024 US EPA drinking-water standards and the EU universal PFAS restriction proposal; assesses the Stockholm Convention and REACH frameworks; and reviews current remediation approaches, including enzymatic degradation, bioremediation and advanced sorbents.