Concentrations and health risk assessment of industrial heavy metals pollution in groundwater in Ogun state, Nigeria

Wastes from industrial activities had great impact on water quality thereby limiting water usability for domestic purposes. Effluents discharge from industries, usually consist of undesirable concentrations of dissolved chemicals that percolate into the groundwater, thus constitute health risk to the populace. The present study assessed the distribution of heavy metals in groundwater and their health implications. Water samples were collected from hand-dug wells and boreholes in the Ota and Sagamu Industrial areas of Ogun state, Nigeria during the rainy and dry seasons. A total of 96 samples (48 samples per season) were collected and subjected to metals analysis (lead (Pb), cadmium (Cd), chromium (Cr), Nickel (Ni), Iron (Fe), Zinc (Zn), Copper (Cu), and Manganese (Mn) using standard methods. Descriptive and inferential statistics were used to analyze the data. The mean concentration of heavy metal in groundwater samples (both seasons) for Pb, Cd, Ni, Cr, Mn, Fe, Zn and Cu were 0.459, 0.006, 0.084, 0.016, 0.100, 0.709, 0.036, and 0.117 mg/L respectively at the Ota sampling location, while at Sagamu, the mean values of respective metals were 0.450, 0.012, 0.082, 0.016, 0.165, 0.663, 0.031, and 0.146 mg/L. The order of presence of the metals in groundwater was in the order Pb > Fe > Ni > Cr > Cd > Cu > Mn > Zn. The total hazard index (HI) of the metals in the groundwater samples showed a high risk across the different age groups. HI value (HI>1.0) demonstrates in general unfavorable non-cancer-causing impacts, in which the infants were at most serious risk. The cumulative Cancer Risk in the study areas shows a medium-extremely high risk for the analyzed metals. The calculated health risk index indicates major adverse effects on human health. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative.