Hg-mining-induced soil pollution by potentially toxic metal(loid)s presents a potential environmental risk and threat to human health: A global meta-analysis

Agricultural activities may promote the conversion of inorganic Hg to MeHg in soil. Hg and As present an extremely and a moderately contaminated level, respectively. The human health risks posed by As, Hg, and Ni merit more attention. Pokeweed may be considered as a potential Hg hyperaccumulator. Soil pollution caused by potentially toxic metal(loid)s (PTMs) near mercury (Hg) mines has attracted extensive attention, yet the status and potential health risks of PTM contamination in soils near Hg mining sites have rarely been investigated on a large scale. Global data on methylmercury (MeHg), Hg, Cd, Cr, As, Pb, Cu, Zn, Mn, and Ni concentrations in soils from Hg mining areas were obtained from published research articles (1999–2023). Based on the database, pollution levels, spatial distributions, and potential health risks were investigated. Results indicated that the average percentage of MeHg to total Hg in agricultural soils (0.19%) was significantly higher than that in non-agricultural soils (0.013%). Indeed, 72.4% of these study sites were extremely contaminated with Hg. Approximately 45% of the examined sites displayed a moderate level of As contamination or even more. Meanwhile, the examined sites in Spain and Turkey exhibited considerably higher pollution levels of Hg and As than other regions. The mean hazard indices of the nine PTMs were 2.91 and 0.59 for children and adults, with 85.6% and 13.3% of non-carcinogenic risks for children and adults that exceeded the safe level of 1, respectively. In addition, 70.2% and 56.7% of the total cancer risks through exposure to five carcinogenic PTMs in children and adults, respectively, exceeded the safety level. As and Hg showed a high exceedance of non-carcinogenic risks, while As and Ni were the leading contributors to carcinogenic risks. This study demonstrates the urgent necessity for controlling PTM pollution and reducing the health risks in soils near Hg mining sites and provides an important basis for soil remediation.