Environmental mercury pollution as a driver of multi-trophic toxicity and human exposure: A one health review of mechanisms, risks, and remediation strategies.

Mercury (Hg) pollution remains a pervasive global environmental health challenge due to its persistence, long-range atmospheric transport, and capacity for biogeochemical transformation into highly toxic and bioavailable forms, particularly methylmercury (MeHg). This review synthesises current knowledge on Hg sources, environmental fate, multi-trophic bioaccumulation, and health impacts, organised within a One Health framework that explicitly links ecosystem contamination, wildlife toxicity, and human disease. Anthropogenic activities now dominate global Hg emissions, driving contamination of aquatic, terrestrial, and agroecosystems far beyond emission hotspots. Microbial methylation in sediments, wetlands, and rice paddies facilitates the production of bioavailable MeHg that undergoes efficient biomagnification of MeHg across food webs, resulting in elevated burdens in fish, wildlife, and human populations reliant on seafood and rice-based diets. Evidence across taxa demonstrates that Hg toxicity is underpinned by conserved molecular mechanisms, including oxidative stress, mitochondrial dysfunction, trace element disruption, endocrine interference, and epigenetic alteration, supporting cross-species extrapolation of risk. In humans, chronic exposure is associated with neurodevelopmental impairment, cardiovascular disease, renal toxicity, immune dysregulation, and intergenerational effects, with disproportionate impacts on vulnerable and socioeconomically marginalised populations. While remediation technologies, emission controls, and international agreements such as the Minamata Convention have reduced some contemporary sources, large reservoirs of legacy Hg in soils, sediments, and biota continue to sustain exposure risks. This review highlights critical knowledge gaps related to climate-mercury interactions, low-dose chronic effects, and combined stressors, and argues that effective Hg prevention and governance require integrated surveillance, mechanistic toxicology, food-system-based interventions, and equity-focused policies within a One Health paradigm.