Hazards of Mercury Toxicity and Other Heavy Metal Intoxication: A Critical Review

Abstract

Heavy metal contamination poses an enduring and increasingly urgent public health challenge. Mercury, lead, cadmium, arsenic, and several other metals occur widely in terrestrial and aquatic environments as a consequence of both natural geological processes and expanding anthropogenic activity. Chronic, low-level exposure to these substances is now recognised as a major driver of non-communicable disease burden globally, contributing to neurological deterioration, renal dysfunction, cardiovascular disease, skeletal pathology, and multiple forms of cancer. Their toxicity is mediated through interconnected mechanisms that include the generation of reactive oxygen species, disruption of intracellular calcium signalling, enzyme inhibition through binding to sulphydryl groups, and impairment of DNA repair. Particularly vulnerable populations include children, pregnant women, artisanal miners, and communities reliant on contaminated drinking water or subsistence fishing. Despite growing scientific understanding and the emergence of international regulatory instruments such as the Minamata Convention, exposures at toxicologically relevant levels remain widespread. This review critically examines the sources, environmental distribution, mechanistic toxicology, clinical manifestations, diagnostic approaches, treatment strategies, and regulatory context of the principal hazardous heavy metals. Evidence drawn from peer-reviewed literature published predominantly between 2000 and 2026 is synthesised to identify knowledge gaps, highlight persistent challenges in clinical management, and inform priorities for future research and policy action. The findings suggested that heavy metal intoxication, being a major global public health threat, require stronger prevention, monitoring, and treatment strategies to reduce its long-term health and environmental impacts. This study is limited by incomplete geographic representation, undercoverage of certain metals and emerging biomarkers, and reliance on existing literature, indicating the need for future large-scale, globally inclusive epidemiological and mechanistic research on heavy metal toxicity.