Contamination status and health risk assessment of potentially toxic trace elements in soils surrounding rare earth tailings in China: A retrospective review

The contamination of soils surrounding rare earth tailings (SRET) with potentially toxic trace elements (PTEs), including Ni, Cd, Cr, As, Pb, Mn, Cu, Zn, and Hg, has garnered increasing scientific concern. However, existing studies predominantly focused on localized regions, limiting insights into nationwide pollution patterns associated with SRET. To address this gap, we systematically compiled and analyzed PTE concentration data from SRET across China using peer-reviewed studies published between 2012 and 2023. The index of geo-accumulation (I_geo) was applied to quantify contamination levels, while Monte Carlo simulation (MCS) was employed to assess uncertainty and sensitivity in health risks posed by ingestion, inhalation, and dermal exposure pathways. Results revealed that average concentrations of Cd, As, Pb, Mn, Zn, and Hg exceeded Chinese soil background values by up to 11.16-fold. I_geo revealed significant Cd contamination in SRET in Inner Mongolia (I_geo = 1.77), Fujian (I_geo = 5.64), and Sichuan (I_geo = 3.89). Moderate Mn contamination was identified in Guangdong (I_geo = 1.80) and Inner Mongolia (I_geo = 1.63). Adults exhibited elevated health risks via oral ingestion of PTEs-contaminated SRET. MCS demonstrated that the median hazard index (HI) and carcinogenic risk (CR) values in five provinces surpassed safety thresholds (CR > 1.00 ×10⁻⁶, HI > 1.00). Sensitivity analyses identified daily soil intake and exposure duration were positively linked to health risks, with As, Ni, Cd, Cr, and Mn concentrations contributing substantially to cumulative risks. This study provides actionable insights for optimizing cost-effective PTE remediation strategies in SRET-affected regions.