Risk associated with heavy metals in children playground soils of Owerri metropolis, Imo State, Nigeria

Abstract

Despite recording the worst heavy metal disaster involving children, there is still scarcity of information on risk assessment of playground soils in Nigeria. In this study, thirty-six soil samples at 0-5 cm depth were collected from nine playgrounds in Owerri metropolis during the dry and rainy seasons. Five heavy metals were fractionated into six chemical fractions using a modified sequential extraction scheme and mean concentrations quantified by AAnalyst 400 Perkin Elmer AAS. Predictive risk models were used to obtain information about the risk of metals contamination to children using these playgrounds for longer periods. These reveal that there were no significant differences in the mean values of bioconcentration factors of all five metals in the various playgrounds for the two years of data. Even though risk values for both dry and rainy season followed the same trend, it was observed that the Zinc showed highest bioconcentration factors (1.6), average daily dose (230.08 mg/kg/day) and risk (5095593 mg/kg/6years). Over all, playgrounds UPS, TSO and SCP had highest mean risk values, respectively. Though with no clear trend, mobility factors showed a weak and positive correlation with risk. Children in playgrounds of public schools within Owerri metropolis could, therefore, be at risk of Mn, Cu and Zn toxicity problems as projected risk values were high for all studied playgrounds. This assessment could help identify playgrounds with urgent need for heavy metals reduction goals, consequently contributing to preserving children’s health