Soil pollution at a major West African E-waste recycling site: Contamination pathways and implications for potential mitigation strategies

Claudia Moeckel,Knut Breivik,Therese Haugdahl Nøst,Alhaji Sankoh,Kevin C Jones,Andrew Sweetman

doi:10.1016/j.envint.2020.105563

Abstract

Organic contaminants (polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and chlorinated paraffins (CPs)) and heavy metals and metalloids (Ag, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, Zn) were analysed in surface soil samples from the Agbogbloshie e-waste processing and dumping site in Accra (Ghana). In order to identify which of the pollutants are likely to be linked specifically to handling of e-waste, samples were also collected from the Kingtom general waste site in Freetown (Sierra Leone). The results were compared using principal component analyses (PCA). PBDE congeners found in technical octa-BDE mixtures, highly chlorinated PCBs and several heavy metals (Cu, Pb, Ni, Cd, Ag and Hg) showed elevated concentrations in the soils that are likely due to contamination by e-waste. PCAs associated those compounds with pyrogenic PAHs, suggesting that burning of e-waste, a common practice to isolate valuable metals, may cause this contamination. Moreover, other contamination pathways, especially incorporation of waste fragments into the soil, also appeared to play an important role in determining concentrations of some of the pollutants in the soil. Concentrations of several of these compounds were extremely high (especially PBDEs, heavy metals and SCCPs) and in some cases exceeded action guideline levels for soil. This indicates that exposure to these contaminants via the soil alone is potentially harmful to the recyclers and their families living on waste sites. Many organic contaminants and other exposure pathways such as inhalation are not yet included in such guidelines but may also be significant, given that deposition from the air following waste burning was identified as a major pollutant source.

Highlights

Large, informal recycling sites for electronic waste (e-waste) are located in a number of developing countries where environmental regulations are much less strict than in many developed countries
The waste is processed in very simple ways, such as dismantling with bare hands, open burning and acid digestion to extract valuable metals from electronic equipment (EEE) that contain often large amounts of plastic materials
Studies conducted at Chinese, Indian, Nigerian and Ghanaian e-waste sites found large concentrations of heavy metals and organic contaminants such as polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in the air, in dust, soil, vegetation and in the blood of workers and residents on and in the vicinity of the sites (Adetunde et al, 2014; Isimekhai et al, 2017; Tue et al, 2016; Labunsk et al, 2013; Daso et al, 2016; Wang et al, 2012; Tang et al, 2010; Akortia et al, 2017; Amankwaa et al, 2017; Chakraborty et al, 2018; Zhang et al, 2012; Hogarh et al, 2018; Caravanos et al, 2011)

Summary

Introduction

Informal recycling sites for electronic waste (e-waste) are located in a number of developing countries where environmental regulations are much less strict than in many developed countries. The waste is processed in very simple ways, such as dismantling with bare hands, open burning and acid digestion to extract valuable metals from EEE that contain often large amounts of plastic materials. These procedures combined with unsystematic and unprotected disposal of the remaining waste have become a large concern from an environmental pollution and human health perspective. Studies conducted at Chinese, Indian, Nigerian and Ghanaian e-waste sites found large concentrations of heavy metals and organic contaminants such as PBDEs, PCBs and polycyclic aromatic hydrocarbons (PAHs) in the air, in dust, soil, vegetation and in the blood of workers and residents on and in the vicinity of the sites (Adetunde et al, 2014; Isimekhai et al, 2017; Tue et al, 2016; Labunsk et al, 2013; Daso et al, 2016; Wang et al, 2012; Tang et al, 2010; Akortia et al, 2017; Amankwaa et al, 2017; Chakraborty et al, 2018; Zhang et al, 2012; Hogarh et al, 2018; Caravanos et al, 2011)

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