Risk assessment of heavy metals in groundwater of Lagos State University, Epe, Lagos State, Nigeria

Risk assessment of groundwater is very important for the protection of the environment and human health. This work was carried out to assess the risk of heavy metals in groundwater of Lagos state University (LASU), Epe campus. 20 different locations for sampling were identified and coordinated using handheld Global Positioning System (GPS) for the purpose of universal identification and virtualization. Groundwater samples were collected from the 20 identified and coordinated locations with the aid of 1 litres plastics bottles which had been treated with 10 % nitric acid and rinsed with de-ionised water. The samples were labeled GW 1 – GW 20 and all the samples were characterized for heavy metals: Zinc (Zn), lead (Pb), copper (Cu), manganese (Mn), cadmium (Cd), nickel (Ni), chromium (Cr) and iron (Fe), using standard methods prescribed by American Public Health Association, American Water Works Association and Water Environment Federation (APHA/AWW/WEF). Heavy metal pollution index (HPI) and metal pollution index (MI) model were used to evaluate the overall quality and the severity of contamination of the groundwater respectively. The possibility of the groundwater to cause non – carcinogenic health problems when consumed was determined using non – carcinogenic health index (HI) model while the possibility to cause carcinogenic health issues was determined with the aid of carcinogenic risk (CR) model. The results revealed that HPI and MI values for LASU, Epe groundwater were 515 and 8.038 respectively. The oral non – carcinogenic health index for child and adult were 3.284 and 0.5166 respectively while the dermal non – carcinogenic values were 0.5159 and 0.0175 for child and adult respectively. The oral carcinogenic values for child and adult were 1051.8 x 10 -5 and 323.9 x 10 -5 respectively for the combined effects of heavy metals while the dermal carcinogenic values were 55.36 x 10 -5 and 0.0137 x 10 -5 for child and adult respectively for the combined effects of the heavy metals. It was concluded that LASU, Epe groundwater have the potential of causing carcinogenic health problems in both children and adults when consumed orally but when taken via dermal, it has the ability to cause carcinogenic health issues in children.