Jose L Domingo, Basem Shomar
Polychlorinated diphenyl ethers (PCDEs) represent a category of persistent organic pollutants (POPs) produced unintentionally during thermal processes and industrial chlorophenol synthesis. Despite possessing structural features and physicochemical properties such as high lipophilicity and long-range transport potential, which are comparable to regulated substances like PCBs and PBDEs, PCDEs are not yet formally restricted under the Stockholm Convention. This review integrates environmental chemistry, ecotoxicology, and public health data through a One Health lens to map their global distribution, which extends to remote polar ecosystems and complex aquatic food webs. Human and wildlife exposure occurs primarily through the consumption of contaminated lipid-rich animal products, with localized risks near legacy industrial sites. Toxicological evidence indicates that planar PCDE congeners act as aryl hydrocarbon receptor (AhR) agonists, triggering dioxin-like effects such as hepatotoxicity and developmental impairment, while non-planar variants potentially disrupt thyroid and estrogenic signaling pathways. Significant research gaps persist regarding human biomonitoring, congener-specific toxic equivalency factors (TEFs), and the influence of climate change on contaminant remobilization. A transdisciplinary One Health strategy, which prioritizes source mitigation, global monitoring harmonization, and the formal evaluation of PCDEs for international regulatory listing, is proposed.