Source-specific probabilistic health risk assessment of potentially toxic elements in soils from a mining area using Monte Carlo simulation: A case study from southwestern Ghana

This study evaluates the impact of mining on soil contamination by conducting a source-specific probabilistic health risk assessment of Potentially Toxic Elements (PTEs) in Southwestern Ghana. Using an Energy-Dispersive X-ray Fluorescence (ED-XRF) spectrometer, 720 soil samples were analyzed for their elemental concentrations. The samples were obtained in 2024 from the B-horizon to provide better accuracy in detecting actual contamination levels linked to illegal mining activities. The PTEs with the highest frequency above their Upper Continental Crustal Averages (UCC) were As(100 %), Ba(13 %), Cr(5.8 %), Pb(2.7 %), Co(2 %), V(2 %), Cu(0.4 %) and Zn(0.4 %). Correlation Coefficient, Self-Organizing Maps (SOM) and Principal Component Analysis (PCA) identified three groups of PTEs, which are geochemically linked elements (Ba, Cr, Cu, Ni, V), anthropogenically influenced As, and a group with low correlations (Co, Pb). Results indicate that anthropogenic activities, such as gold extraction, partly drive As distribution. Geoaccumulation and Pollution Indices reveal varying levels of pollution in As, Cr, and Pb. Health risk assessments, using deterministic and probabilistic methods, found that while non-carcinogenic risks were within safe limits for adults (Hazard Index [HI] < 1), children faced higher risks (HI > 1) for As, Cr, Co, and V. Carcinogenic risks for both groups were within the acceptable threshold (10⁻⁴–10⁻⁶), with children at greater risk. Ingestion was identified as the primary exposure pathway. The study highlights the higher susceptibility of children to PTE pollution, emphasising the need for interventions to mitigate risks from PTEs.