Polychlorinated naphthalenes through the one health Lens: Unmasking a global threat to humans, wildlife, and ecosystems

Polychlorinated naphthalenes (PCNs) represent a significant yet underappreciated threat to humans, animals, and environmental health. As persistent organic pollutants listed under the Stockholm Convention, PCNs exhibit properties characteristic of dioxin-like compounds: environmental persistence, bioaccumulation potential, long-range transport capability, and toxicity mediated primarily through the aryl hydrocarbon receptor (AhR). Despite cessation of intentional production in most countries, PCNs continue to contaminate ecosystems globally through unintentional emissions from industrial processes, particularly waste incineration and metallurgical operations. This review synthesizes current knowledge on PCNs through an explicit One Health lens, examining their shared sources, environmental fate, and convergent health impacts across species. Human and wildlife populations face exposure through dietary intake, with fish serving as primary bioaccumulation reservoirs. Toxicological effects span immunosuppression, hepatotoxicity, neurotoxicity, endocrine disruption, and reproductive impairment, with remarkable consistency across vertebrate species, validating cross-species risk assessment approaches. Vulnerable populations, including subsistence communities relying on traditional foods and workers in specific industries, face disproportionate risks. Legacy contamination from historical manufacturing combined with ongoing unintentional emissions creates a persistent global challenge requiring integrated monitoring, transdisciplinary research, and harmonized regulatory frameworks. The One Health paradigm provides an essential model for developing collaborative solutions that simultaneously protect human, animal, and ecosystem health. The case of PCNs powerfully illustrates that the health of the environment is a fundamental determinant of the health of the animals and humans within it. This review advances the field by providing the first One Health synthesis of PCNs contamination, offering integrated strategies to address shared risks across species and ecosystems.