Environmental risk assessment for an informal e-waste recycling site in Lagos State, Nigeria

It has been recognised that the informal E-waste recycling may pose a risk to human health and the environment, this study aims to evaluate the e-waste contamination and the environmental and human health impact of informal e-waste recycling on the exposed population using the risk assessment framework. The distribution of a number of heavy metals in soil from an informal recycling site in the largest market for used and new electronics and electrical equipment in West Africa was investigated. The extent of pollution, potential bioavailability of heavy metals, potential risk due to the recycling activities and impact of external factors such as rainfall were assessed. In recent times, bioaccessibility has emerged as a testing tool used to accurately estimate the risk posed on human health by exposure to environmental contaminants, the oral bioaccessibility and inhalation bioaccessibility was also assessed. The concentrations of all the identified metals in the recycling site were consistently higher than values obtained from the control site, suggesting the impact of the recycling activities on the soil. The order of total metal concentration was Cu > Pb > Zn > Mn > Ni > Sb > Cr > Cd for both the dry and wet season. The total concentration of Cd, Cu, Mn, Ni and Zn where was significantly higher (p≤0.001) in the dry season than in the wet season. The concentrations of Cu (329-7106 mg kg-1), Pb (115-9623 mg kg-1) and Zn (508-8178 mg kg-1) were consistently higher than the international soil guideline values. Using a sequential extraction method, the potential bioavailability of the metals was indicated as Cd > Sb > Zn > Cu > Ni > Pb > Cr, suggesting Cd was the most potentially available. Assessing the risk using the Potential Ecological Risk Index (PERI), Cu was found to contribute the most to the potential ecological risk and Cd the greatest concern due to its high toxic-response factor within the study site and the Risk Assessment Code (RAC) suggested Cd posed the most risk in this site. Furthermore, the oral bioaccessibility test showed that less than 40% of the total concentration of all the identified metals was potentially available for absorption in the gastrointestinal tract. In the inhalation bioaccessiblity, with the exception of Cd, the percentage bioaccessibility of the other metals was less than 35% after 120 hours. The health risk characterization indicated the adverse human health effect through the ingestion pathway and a relative lower probability of risk through the inhalation of pathway. This study established a high level of contamination as a result of the informal recycling activities, underscores the importance of applying speciation and bioaccessibility and bioavailability in risk assessment. Finally, in an attempt to evaluate the risk, the study proposed an integrated risk assessment framework which when tried and tested is aimed to positively influence the risk judgement and ultimately risk management decisions whereby providing valuable insights that would translate to an efficient and sustainable management system at the long run

Heavy metals distribution and risk assessment in soil from an informal e-waste recycling site in Lagos State, Nigeria

Informal e-waste recycling can pose a risk to human health and the environment, which this study endeavours to evaluate. The distribution of a number of heavy metals in soil from an informal recycling site in the largest market for used and new electronics and electrical equipment in West Africa was investigated. The potential bioavailability of heavy metals, extent of contamination, potential risk due to the recycling activities and impact of external factors such as rainfall were also assessed. The concentrations of all the metals tested were higher in area where burning of the waste occurred than the control site, suggesting an impact of the recycling activities on the soil. The order of total metal concentrations was Cu > Pb > Zn > Mn > Ni > Sb > Cr > Cd for both the dry and wet seasons. The total concentration of Cd, Cu, Mn, Ni and Zn were all significantly higher (p Sb > Zn > Cu > Ni > Pb > Cr. Whern the risk was assessed using the Potential Ecological Risk Index (PERI), Cu was found to contribute the most to the potential ecological risk and Cd gave rise to the greatest concern due to its high toxic-response factor within the study site. Similarly, the Risk Assessment Code (RAC) suggested Cd posed the most risk in this site. This research establishes a high level of contamination in the study site and underscores the importance of applying the appropriate chemical speciation in risk assessment

Risk assessment at an informal e-waste recycling site in Lagos state, Nigeria

E-waste is referred to obsolete, broken electronic devices such as mobile phones, televisions, computer monitors, laptops, printers, scanners, and associated wiring (Luther, 2010). E-waste is generated in large quantities (Tang et al., 2010); the composition of the waste creates a major problem. E-waste contains more than 1000 different substances, many of which are toxic metals and organic pollutants (Robinson, 2009). These include lead and cadmium in circuit boards; lead oxide and cadmium in monitor cathode ray tubes (CRTs); mercury in switches and flat screen monitors; cadmium in computer batteries; polychlorinated biphenyls (PCBs) in older capacitors and transformers; and brominated flame retardants on printed circuit boards, plastic casings, cables and polyvinyl chloride (PVC) cable insulation that release highly toxic dioxins and furans when burned to retrieve copper from the wires (BAN, 2002). Also, polybrominated diphenyl ethers (PBDEs) are used as brominated flame retardants in electronic circuit boards (Wang et al., 2005). Activities carried out in the site of interest include dismantling of the different electronic waste, sorting out of various parts and burning of wires and other parts to get valuable metals.The complex composition of e-waste may pose a threat to the environment and human health if they are not disposed correctly

Global occurrence, chemical properties, and ecological impacts of e-wastes (IUPAC technical report)

The waste stream of obsolete electronic equipment grows exponentially, creating a worldwide pollution and resource problem. Electrical and electronic waste (e-waste) comprises a heterogeneous mix of glass, plastics (including flame retardants and other additives), metals (including rare earth elements) and metalloids. The e-waste issue is complex and multi-faceted. In examining the different aspects of e-waste, informal recycling in developing countries has been identified as a primary concern due to widespread illegal shipments, weak environmental as well as health and safety regulations, lack of technology and inadequate waste treatment structure. For example, Nigeria, Ghana, India, Pakistan and China have all been identified as hotspots for the disposal of e-waste. This article presents a critical examination on the chemical nature of e-waste and the resulting environmental impacts on, for example, microbial biodiversity, flora and fauna in e-waste recycling sites around the world. It highlights the different types of risk assessment approaches required when evaluating the ecological impact of e-waste. Additionally, it presents examples of chemistry playing a role in potential solutions. The information presented here will be informative to relevant stakeholders to devise integrated management strategies to tackle this global environmental concern