A review and meta-analysis on heavy metals in soils and crops at metal mines: Accumulation, source, food safety, health risk, and management

Natural and anthropogenic anomalies in heavy metals at metal mines have posed ecological risks, threatened food safety, and posed potential risks to the health of local inhabitants, thereby challenging the achievement of the United Nations Sustainable Development Goals. Concentrations of heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) in the soils at 76 mines as well as their accumulation in 108 crop species, such as brassica vegetables (13), leafy vegetables (32), nonleafy vegetables (27), legume vegetables (9), fruit (19), cereal (7), and rice (1), at 81 metal mines in 29 countries were systematically reviewed and comprehensively analyzed. High pollution index values ( P I =2.2–3497, median of 40.7) indicated high to very high potential ecological risks (75.0% of reviewed mines) at metal mines. Arsenopyrite and As-rich pyrite may be the primary sources of As pollution. Cd and Pb accumulated to a significantly greater extent in rice than in other types of crops ( p < 0.001). The meta-analysis of metal concentrations in soils and health risks revealed substantial heterogeneity across studies (I² = 71.3–99.9%, p < 0.001). Health risks associated with crop consumption were greater than those associated with soil exposure. The very high non-cancer-related health risk ( H I =2.6–744, median of 37.8) and incremental lifetime cancer risk ( I L C R =2.69E-03–3.38E-01, median of 3.05E-02) via crop consumption indicated that without effective management, crops with metal concentrations higher than the allowable limits and a bioconcentration factor ( BCF ) > 1 should not be cultivated at metal mines to minimize health risks. Pollution source management, metal remediation, reduction of metal uptake by crops, and phytomanagement were proposed and discussed. These results are vital for taking immediate and proper measures to ensure safer crops, reduce ecological and health risks, and manage metal mines.