Distribution and potential risk of metals and metalloids in soil of informal E-waste recycling sites in Lagos, Nigeria

Abstract

Crude and haphazard informal e-waste recycling has resulted in environmental pollution with detrimental effects on human health. The present study assesses the levels of metals and metalloids (Pb, Mn, Fe, Zn, Co, Cd, Ni, Ag, Cu, As, Ba, Cr, Ca, Mg, K, and Na) in topsoil of informal e-waste recycling sites in Lagos, Nigeria. Topsoil samples (0-15 cm) were randomly collected at different informal e-waste recycling hubs in Lagos. Samples were digested and the levels of heavy metals and metalloids were determined using ICP-OES. Soil contamination indices, ecological and human health risks were evaluated using contamination factor, degree of contamination, geo-accumulation index, ecological risk index (RI), and human risk index (HI), respectively. There were variations in the concentrations of metals and metalloids in the soil, which ranged from 7.05-16,350 mg/kg Pb, 14.4-3,373 mg/kg Cu, ND-21.9 mg/kg Cd, and ND-166 mg/kg Ni. Lead had the highest mean concentration of 7394 ±7759 mg/kg in soil around the dismantling points at Ojota scrap market. Ojota scrap market also had the highest concentrations of all the metals except Co, Cd, As and Ba. Health risk index (HI) ranged from 3.93-183 in both children and adults populations. These calls for concern due to potential health risk associated with human exposure to toxic metals, some of which are also endocrine disruptors. There is need for proper management of e-waste in Nigeria to prevent human exposure to these toxic substances present therein.

Keywords: Electronic waste, environmental contamination, heavy metals, recycling, health risk, waste management