Groundwater contamination and human health risk assessment in Ikire community, Osun State, Nigeria

Groundwater quality and its potential health risk around a municipal dumpsite in Ikire, Southwest Nigeria was investigated using ten groundwater samples which were analyzed for physicochemical parameters. The methods used were groundwater sampling, analyses, spatial distribution of heavy metal (Cd, Cr, Cu, Fe, Mn, Pb, and Zn) and quantitative health risk analysis using USEPA equations. The chronic daily intake (CDI), hazard quotient (HQ), and hazard index (HI) were used to examine potential human health risks of heavy metal pollution. The mean concentration values of Cl-, Ca2+, K+ Mg2+, Fe, Cd, Pb and Mn were higher than their respective permissible limits, while the mean concentration values HCO3-, Cu and Zn were within their respective limits. The HQ values of the heavy metals via oral ingestion for the children and adults are found in the order: Cd > Pb > Mn > Fe > Zn > Cu and Cd > Pb > Mn > Zn > Cu > Fe, respectively. The HI values via ingestion pathway for all heavy metals were beyond the threshold value of 1.0, indicating high contamination adverse health risk due to an undesirable level of heavy metals. Cadmium is a major contributor to non-cancer effects in children and adults in the groundwater samples in the region. The groundwater is unsafe for drinking and should be treated before domestic consumption.