Persistent Organic Pollutants: Chemistry, Environmental Fate, and Toxicological Impact

Abstract

Persistent organic pollutants remain one of the most consequential classes of anthropogenic chemicals identified in modern environmental science. Their defining characteristics, chemical stability, resistance to biotic and abiotic degradation, high lipophilicity, and capacity for long-range transport, allow them to accumulate in soils, waters, sediments and living tissues far from the point at which they were released. This review synthesises current understanding of the chemistry underpinning environmental persistence, the mechanisms governing global transport and fate, and the toxicological consequences observed in wildlife and human populations. The molecular architecture of legacy pollutants such as polychlorinated biphenyls, dichlorodiphenyltrichloroethane, dioxins and furans is examined alongside emerging classes including per- and polyfluoroalkyl substances, polybrominated diphenyl ethers and chlorinated paraffins. Attention is given to the physicochemical descriptors that predict environmental behaviour, the phenomenon of global fractionation that concentrates certain compounds in polar and mountain regions, and the trophic processes of bioaccumulation and biomagnification that elevate exposure in apex predators and human consumers. Toxicological evidence spanning endocrine disruption, immunotoxicity, reproductive and developmental harm, and carcinogenicity is critically appraised, with particular focus on receptor-mediated mechanisms such as aryl hydrocarbon receptor activation. The governance architecture established under the Stockholm Convention is evaluated, including persistent implementation gaps in low- and middle-income regions and the accelerating identification of emerging contaminants requiring regulatory attention. The review closes by identifying priority research directions, drawing overall conclusions, and outlining the methodological limitations inherent to a narrative synthesis of this breadth.