HEALTH RISK ASSESSMENT OF HEAVY METALS IN GROUND WATER SAMPLES FROM STUDENT RESIDENCES OF HIGHER INSTITUTION

Abstract

Anthropogenic and geogenic contamination have led to pollution of ground water with high levels of heavy metals. This study assessed the health risk of heavy metals in ground water samples from student residences of Olabisi Onabanjo University, Ago-Iwoye, Nigeria. Physicochemical properties were determined using standard analytical procedures while heavy metals [Zinc (Zn), Manganese (Mn), Iron (Fe), Nickel (Ni), Cadmium (Cd), Lead (Pb)] concentrations were determined using Atomic Absorption Spectrometer. The carcinogenic and non-carcinogenic health risks assessment via oral and dermal contact was estimated in terms of hazard quotient (HQ) and cancer risk (CR). The results of samples' physicochemical properties include; temperature (≤ 28.9 oC), pH (≤7.06), turbidity (≤2.65 NTU), Electrical Conductivity (≤474 µS/cm), Total Suspended Solid (≤4.00 mg/I), Total Dissolved Solid (≤207.00 mg/l), Total Acidity (≤300.00 mg/I), Total Hardness (≤172.00 mg/l ), Chloride (≤25.00 mg/I), Dissolved Oxygen (≤5.66 mg/l), Nitrates (≤3.90 mg/I), phosphates (≤0.78 mg/l), and sulphates (≤46.50 mg/l) with only total hardness that is above the WHO permissible limit. The concentrations of Zn, Mn, Fe, Ni, Cd, Pb (mg/L) are ≤0.055, ≤1.138, ≤0.363, ≤0.052, ≤0.008, BDL respectively and all are below the WHO permissible limits except Mn. The HQ and HI for non-carcinogenic health risk through oral and dermal exposure to Ni and Cd considered in this study is below unity and with no risk except Mn in AR sample. The CR values in all sites were within the acceptable cancer health risk range of 1.00 × 10-4 to 1.00 × 10-6 except for Ni at site MR.