Health risk associated with some toxic elements in surface water of Ilesha gold mine sites, southwest Nigeria

Health risk assessment of toxic elements in water bodies around gold minesites within southwest Nigeria and implication on the miners and residents was carried out in this study. A total of twenty five surface water samples were analysed for some toxic elements such as Pb, As, Cu, Cd, Zn, Co, Fe, Mn, Cr and Ni using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The results showed that Fe, Ba, Mn, Pb, Cr and Ni exceeded the recommended standards deem fit for human consumption in 62.5%, 18.25%, 37.5%, 12.5%, 6.25% and 6.25% of the water samples respectively. Contamination Index showed that 20% of the water samples can be classified as highly contaminated, 24% can be classified as slightly contaminated and only 16% as not contaminated. The hazard quotient values calculated for all toxic elements based on ingestion and dermal exposure to water showed value <1 which is acceptable level of non-carcinogenic adverse health risk for children and adults except Cr and V for only dermal exposure with values >1. The health risk index calculated for toxic elements through both ingestion and dermal exposure showed that 16% of the water samples were within unacceptable risk for non-carcinogenic adverse health effect based only on dermal exposure route and Cr, V, Mn, Sb, Fe and As contributed highest to the risk. Cancer risk showed that only Arsenic exceeded acceptable risk for carcinogenic adverse health risk for children and adults and this make Arsenic to be carcinogenic in the water of the study area.