Maigari A. U.^1,, Ekanem E. O.², Garba I. H.², Harami A.², Akan J. C.³

The concentrations of eight heavy metals (Fe, Mn, Cu, Pb, Cd, Ni, Co and Zn) were determined by atomic absorption spectroscopy in water from Dadinkowa dam and Kwadon boreholes which are the major sources of drinking water to Gombe town in Gombe State, North-East, Nigeria. The concentrations of metals in water from Dadinkowa dam were in the order: Fe (1.86mg/l), Mn(0.68mg/l), Cu(0.92mg/l), Pb(0.19mg/l), Cd(0.50mg/l), Ni(0.59mg/l), Co(0.42mg/l) and Zn(0.83mg/l).The concentrations of the metals in water from Gombe Abba River were in the order Fe(0.21 mg/l), Mn (0.24 mg/l), Cu (0.29 mg/l), Pb (0.02 mg/l), Cd (0.10 mg/l), Ni( 0.04 mg/l), Co(0.12 mg/l) and Zn (0.41 mg/l). The human health risk assessment was performed by determining the chronic daily intake (CDI), hazard quotient (HQ) and total hazard index (THI) of the metals through human oral consumption for both adults and children. The HQ of iron, manganese, nickel and cobalt in water from Dadinkowa dam were all greater than unity and thus pose a potential health risk for both adults and children while cobalt was the only heavy metal of concern in water from Gombe Abba River as its HQ was greater than unity. The THI of water from all the sampled sites assessed were of high risk. Further monitoring of these sites is recommended as well as research by biomedical experts to reveal the exact adverse effects that heavy metal contamination of water might induce in humans, particularly among individuals in vulnerable populations such as children.

atomic absorption spectroscopy, chronic daily intake, drinking water, hazard quotient, health risk assessment, heavy metals, total hazard index