RISK ANALYSIS OF INFORMAL RECYCLING OF ELECTRONIC WASTE IN LAGOS STATE, NIGERIA

Electronic waste (e-waste) is an increasingly problematic issue arising from discarded electronic appliances, such as computers and mobile phones, which recycling the e-waste can recover reusable materials. It is a source of... [ view full abstract ]

Electronic waste (e-waste) is an increasingly problematic issue arising from discarded electronic appliances, such as computers and mobile phones, which recycling the e-waste can recover reusable materials. It is a source of opportunities due the high economic value of the components but is also generating attention due to the potential environmental problems resulting from the presence of hazardous substances. However, as a result of high cost of recycling and strict environmental regulations, the discarded electronics are exported to developing countries, where the waste may be recycled using primitive techniques with no regard to the environment, health or workers safety. In Nigeria, for example, e-waste ends up in landfills and the informal recycling of discarded electronics is encouraged and thrives due to its economic benefits. Activities carried out include dismantling of the different electronic waste and burning of wires and other parts to recover valuable materials for resale. Exposure to contaminated soil is an important pathway in human health risk as contaminants can directly pose significant risks through oral ingestion, particle inhalation, and dermal contact. Risk assessment provides a framework for a structured review of information relevant to estimating health or environmental outcomes. This study aims to assess the impact of the improper recycling activities on the soil as well as human exposure of the populace at and near the recycling site. The soil was analysed for total metal concentration using ICP-OES, the bioavailable concentration and the human oral bioaccessibility fraction was determined by simulating the digestive process the using the Unified BARGE method to estimate the environmental and health risk posed. The concentration of investigated heavy metals were present in the following order Cu > Pb > Zn > Mn > Ni > Sb > Cr > Cd with Cu ranging between 329-9277mgkg-1; Pb 115-9623 mgkg-1; Cd 0.88-70.2 mgkg-1. In comparison with other metals, Cd showed the highest bioavailability, with approximately 40% of the total Cd concentration found to be readily available for uptake. The oral bioaccessibility of the metals indicated that about 40% of the total concentration of each metal was available for absorption when ingested. These results will be discussed in terms of the proportion of the total metal content that is available for uptake in order to develop a realistic estimation of the risk posed to the environment by the improper recycling activities via the soil pathway.