Assessing global patterns and health risks of vegetables as a dietary mercury exposure pathway

Mercury (Hg) is a globally distributed toxic pollutant with well-documented neurotoxic and nephrotoxic effects, yet comprehensive assessments of Hg contamination in vegetables-a potentially significant dietary exposure pathway for non-fish-consuming populations-remain lacking. This study presents the first global assessment of Hg concentrations in edible vegetables by compiling 8546 records from 49 countries, integrating data from peer-reviewed literature, the WHO GEMS Food contaminants database, and national Total Diet Studies. The compiled dataset revealed pronounced geographic inequalities in monitoring coverage, with high-income countries contributing the majority of observations while many low- and middle-income regions remained substantially underrepresented. Despite these data gaps, the global median Hg concentration was 0.0012 mg/kg, suggesting that vegetables generally constitute a secondary exposure pathway relative to fish and seafood. However, regional median concentrations varied by nearly 50-fold, from 0.00014 mg/kg in North America to 0.0067 mg/kg in the Middle East and North Africa, with extreme values recorded in Côte d'Ivoire (0.140 mg/kg) and Bosnia and Herzegovina (0.057 mg/kg). Temporal analysis revealed divergent trajectories: while emission controls drove a 58 % reduction in median concentrations in China (from 0.0024 to 0.0010 mg/kg), high contamination levels persisted in regions with unregulated mining. Correlation analyses indicated that PM2.5 (r = 0.49) and artisanal gold mining emissions (r = 0.46) exhibited the strongest positive associations with vegetable Hg concentrations, implicating atmospheric deposition as a predominant contamination pathway. Probabilistic risk assessment identified Côte d'Ivoire and Bosnia and Herzegovina as potential high-risk hotspots, where estimated Hazard Quotients (HQ) exceeded the safety threshold for both children (HQ: 1.05-1.39) and adults (HQ: 1.47-1.95). Sensitivity analyses confirmed that the identification of these priority regions remains robust to demographic uncertainties. These findings demonstrate that in specific inland hotspots, vegetable-borne exposure rivals aquatic pathways, underscoring the urgent need for expanded surveillance in the Global South.