Ecological risk and human health implications of heavy metals contamination of surface soil in e-waste recycling sites in Douala, Cameroun

Abstract

Background. Recycling of electronic waste (e-waste) in developing nations poses a risk to the environment and human health through the release of heavy metals. Objectives. The aim of the present study was to evaluate the levels of heavy metals in Douala, Cameroun, the site of e-waste recycling activities. Methods. Soil samples were collected from Makea, Ngodi and New Bell e-waste recycling sites, as well as from a control site. Samples were digested and levels of heavy metals were determined. Results. The concentrations of the heavy metals in Makea occurred in the order of lead (Pb) (290×40) > zinc (Zn) (160×30) > chromium (Cr) (130×40) > copper (Cu) (130×20) > nickel (Ni) (56×5.7) > cadmium (Cd) (20×3.0); Pb (310×30) >Zn (150×20) >Cu (80×30) >Cr (70×40) >Ni (50×1.0) >Cd (30×5.0) in Ngodi; and Pb (280×40) >Zn (155×35) >Cu (80×50) >Cr (70×40) >Ni (53×2.0) >Cd (20×10) in New Bell. The levels of metals in all of the samples were higher compared to the control site, which was composed of vegetation and far from the e-waste sites, and in some cases, higher than permissible limits or guidelines. The ecological risk index of heavy metals for soil samples in all the e-waste sites indicated a very high risk. Conclusions. Heavy metals concentrations in soil around e-waste recycling sites present serious health risks and further investigations are needed. Competing Interests. The authors declare no competing financial interests.