Vanadium in environmental and biological systems: From industrial contaminant to insulin-mimetic agent.

Vanadium has emerged as a significant environmental contaminant of global concern, with increasing attention directed toward its complex biogeochemical behavior and potential health implications. This review provides a critical and integrative synthesis of environmental vanadium distribution, fate, and toxicological effects, with emphasis on speciation-dependent behavior, exposure pathways, and uncertainties in epidemiological inference. Vanadium exists in multiple oxidation states, with V(V) generally more mobile and often more toxic than V(IV), although toxicity is context-dependent. Industrial activities, particularly steel production, petroleum refining, and mining operations, contribute substantially to environmental vanadium loads. Environmental epidemiological studies have reported associations between vanadium exposure and adverse health outcomes, although exposure misclassification, co-pollutant confounding, and limited compound-specific data restrict causal inference. Recent cross-sectional evidence suggests associations between urinary vanadium and early kidney injury biomarkers in children, but longitudinal studies are needed to determine causality and clinical relevance. Paradoxically, in recent decades vanadium compounds showed promise as antidiabetic agents. However, serious concerns over long-term toxicity prevented their clinical application. Vanadium exhibits a dual role in biological systems, showing beneficial effects at low concentrations, while inducing oxidative stress and cytotoxicity at high levels. Phytoremediation and microbial bioremediation strategies are promising for environmental cleanup, with several plant species demonstrating hyperaccumulation capabilities. This review identifies critical knowledge gaps including limited understanding of vanadium speciation in marine environments, insufficient long-term epidemiological data, and the need for standardized risk assessment frameworks. Given the projected increase in vanadium applications, particularly in vanadium redox flow batteries (VRFBs) for energy storage, comprehensive environmental monitoring and regulatory frameworks are urgently required to mitigate potential risks to ecosystem and human health.