Assessing Human Health Risks in Asejire Lake: Implications for Water Resources in Industrialized Ibadan, Nigeria

Human health risk assessment of Asejire Lake in densely populated and industrialized Ibadan city has been examined using Average Daily Dose (ADD), Hazard Quotient (HQ), Hazard Index (HI), Chronic daily intake (CDI) and Carcinogenic Risk (CR) calculated from the hydrochemical analysis results of Aluminum, Barium, Chromium, Copper, Iron, Manganese, Nickel, Lead and Zinc. ICP-MS laboratory technique was used from which the results of the selected trace elements were extracted. The average values of Ba, Al, Cr, Fe, Cu, Mn, Pb, Ni and Zn are: 0.08ppm, 0.39ppm, 0.001ppm, 1.41ppm, 0.004ppm, 0.068ppm, 0.004ppm, 0.002ppm and 0.035ppm respectively which are all below prescribed standards except Al and Fe. The average values of TDS, EC and pH are: 51.73ppm, 100μS/cm and 7.4 respectively which show that the water is non-saline but slightly alkaline in nature. The average values of ADD, HQ, and HI for all age groups were generally <1 falling within low chronic risk for HI. However, Values computed for children are close to unity and caution must be taken for children’s consumptions both in ingestion and derma absorption. Order of abundance of average CDI is: Fe>Al>Ba>Mn>Zn>Pb>Cu>Ni>Cr respectively. Average CR for Cr and Pb fall within 10-6 and 10-4 and above respectively and this gives a signal for cancer risk in consumption. Based on WHO background values, there are elevated values of average Contamination Factor (CF) above one for Al (2) and Fe (5) depicting some degrees of contamination in water phase and Degree of Contamination also ranged from 7 to 9 (average, 8) indicating low to moderate degree of contamination. Al and Fe sourced from the various anthropogenic and lithogenic activities contributed significantly to metal loading in the water which are of health significant.