Quantitative and health risks evaluations of trace metals in soils and cassava tubers cultivated in farms around abandoned Ishiagu mining sites, Ebonyi State, Nigeria.

Environmental contamination with toxic metals poses significant risks to food safety, particularly in regions with abandoned mining sites. This study investigates the concentration and potential health risks of trace metals-manganese (Mn), copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), selenium (Se), strontium (Sr), niobium (Nb), vanadium (V), and iron (Fe)-in soil and their bioaccumulation in cassava tubers cultivated near abandoned mining sites in Ishiagu, Ebonyi State, Nigeria. Using X-ray fluorescence spectrometry, the study found substantial accumulation of toxic metals in farmland soils within the mining vicinity, with Pb showing the highest mean concentration (1309 ± 103 mg/kg) and Sr the lowest (78 ± 9 mg/kg). Cassava tubers grown in these contaminated soils exhibited significantly higher levels (P < 0.05) of toxic metals compared to those from uncontaminated reference soils, with Pb (889 ± 63 mg/kg) and Fe (1826 ± 89 mg/kg) concentrations exceeding permissible limits established by the World Health Organization, while Mn showed the lowest concentration (132 ± 19 mg/kg). Health risk assessments revealed hazard index values exceeding 1, with Pb demonstrating the highest target hazard quotient values of 485.71 for children and 180 for adults, indicating significant health risks associated with the consumption of contaminated cassava. The estimated daily intake (EDI) of Pb was 0.63 mg/kg/day for adults and 1.7 mg/kg/day for children, far exceeding safe thresholds. These findings underscore the urgent need for mitigation strategies to reduce heavy metal exposure in affected communities and ensure food safety, particularly for vulnerable populations like children who face disproportionate risks due to their lower body weight and higher ingestion rates relative to adults.