Heavy Metals in the Urban Soils and Vegetables in Jos Metropolis, Nigeria: Implications on Children’s Health

Abstract

The act of scavenging for food on harvested farms, metal substance in waste dumps and playing football games are common among children in the Jos metropolis, north central Nigeria. The aftermath of these activities (eating with unwashed hands, inhalation of dust during playing and transportation activities within the metropolis and consumption of vegetables may expose children to the constituent heavy metals. The aim of this study was to determine concentration of heavy metals in the urban soils and their levels in vegetables grown and consumed by residents of Jos Metropolis, with the view to drawing inferences on probable health implications on children who are the vulnerable group in the society. An assessment of the level of contamination or accumulation of the heavy metals in the soils was carried out using an index of geo-accumulation (Igeo) and the transfer factor (TF) from soil to vegetables and its health risk index (HRI) were calculated. Geochemical results obtained from the analysis soil samples (from the playgrounds, stream sediments, farm soils and soil dump) and vegetables samples show that the soils in the playground are generally enriched in Al2O3 and Fe2O3 (10.99 and 10.21 wt% respectively). The heavy metals content of the soils are elevated (Co, Cr, Pb and Zn; 146, 66, 268 and 219 ppm respectively). Most of the heavy metals (As, Co, Cr, Cu, Ni, Pb and Zn) in the playgrounds display Igeo <1 suggesting that the playgrounds are safe and pose no risk to the health of children who play on it. All the variety of vegetables display different metal absorption capabilities with Cu being the highest (TF = 3 – 6).The intake of Zn and Pb into these vegetables are minimal. The calculated HRI for Pb, Zn and Cu are <1 suggesting that the consumption of these vegetables is safe and pose no potential human health risks.