Health Risk Assessment of Heavy Metals in Soil where Medicinal Plants are grown on abandoned mine site in Fefur of Jos East LGA, Plateau State.

Abstract

Heavy metal accumulation and biomagnification in abandoned mining environments pose 
significant environmental and public health concerns, particularly where contaminated soils 
support the growth of medicinal and edible plants. This study assessed the concentration, 
spatial distribution, and potential health risks associated with heavy metal contamination in 
abandoned tin-mining soils from Fefur, Jos East Local Government Area, Plateau State, 
Nigeria. Soil samples were analyzed for seven heavy metals: Manganese (Mn), Copper (Cu), 
Lead (Pb), Iron (Fe), Cadmium (Cd), Zinc (Zn), and Nickel (Ni), using Inductively Coupled Plasma 
Mass Spectrometry (ICP–MS). The potential non-carcinogenic health risks associated with 
the consumption of traditional medicinal plants cultivated in the area were evaluated for 
adults and children using Target Hazard Quotients (HQs). The results revealed elevated 
concentrations of heavy metals in the mine soils, with mean levels of Mn, Cu, Zn, Fe, Ni, and 
Pb exceeding established maximum permissible limits. Notably, Ni and Pb concentrations were 
substantially higher than the guideline values recommended by the World Health Organization 
(WHO), indicating significant contamination arising from historical mining activities. Elevated 
Cu concentrations further confirmed the persistence of mining-derived pollutants within the 
soil environment. Geographic Information Systems (GIS)-based interpolation maps showed 
pronounced hotspots of Pb, Ni, and Cu around abandoned mine pits and tailings, highlighting 
strong anthropogenic influence. Moderate concentrations extending into nearby farmlands 
suggest contaminant dispersion through erosion and surface runoff. Although the calculated 
HQ values for individual metals were below the critical threshold of one (HQ < 1), indicating 
a low likelihood of immediate non-carcinogenic effects, prolonged exposure through 
continuous ingestion of contaminated plants may result in metal bioaccumulation and potential 
carcinogenic risks. Continuous environmental monitoring and remediation measures are 
therefore recommended to safeguard ecosystem and human health.