Occurrence, metallo-toxicological interactions, and health risks of selected potentially toxic elements in the River Offin, Ghana

Illegal gold mining in the River Offin watershed is causing significant environmental concerns due to the discharge of potentially toxic elements (PTEs) into aquatic ecosystems. This study assessed the occurrence, accumulation, and health implications of arsenic (As), mercury (Hg), and selenium (Se) in water, sediments, and fish from the Offin River, Ghana. Physicochemical parameters, water quality index (WQI), pollution indices, bioconcentration (BCF), biota-sediment accumulation factors (BSAF), and synergistic and antagonistic effects of PTEs were evaluated, and pollution sources were assessed using multivariate statistical analyses. The findings indicated Hg, As, EC, Se, and turbidity concentrations exceeded the guideline limits in water, sediments, and fish samples. The WQI of 7460.609% indicated the water is unsuitable for domestic and agricultural activities. The multivariate analysis revealed that the mercury-based gold mining method influenced the sources, mobility, and transport of contaminants. Based on the health risk assessment, there is a significant likelihood of cancer and other adverse health effects, especially in children, with noncarcinogenic hazard quotients > 1 and carcinogenic risk > 1.00E-4. The synergistic and antagonistic evaluations revealed Se: Hg, Se: As ratios < 1, and Se-HBV < 1, suggesting insufficient selenium protection against Hg and As toxicity in fish, while As: Hg > 1 suggested enhanced Hg toxicity. BCF and BSAF values confirmed that Hg and As accumulate more readily from water to fish than from sediment. This study reinforces the urgent critical for regulatory attention, environmental surveillance, and community awareness to combat illegal mining, minimize PTE exposure and preserve aquatic life and public health in the River Offin basin.