Toxicity evaluation of E-waste plastics and potential repercussions for human health

Abstract

At present, waste mobile phone is considered to be one of the fastest-growing obsolete items in the stream of electronic waste (e-waste). Toxic substances such as heavy metals and brominated flame retardants (BFRs) have been widely added to plastics used in electrical and electronic equipment (EEE). The recent technological revolution in electronic appliances combined with high and growing consumption has caused a huge generation of waste electrical and electronic equipment (WEEE). Therefore, e-waste plastics are considered to be one of the fastest-growing waste streams globally. In this study, we examined the hazardous substances in the plastic components of waste mobile phones and then applied the USEtox life cycle impact assessment (LCIA) model to determine the impacts on human health. Specifically, various plastic parts separated from waste mobile phones (n = 20) were collected and then, we used standard tests to characterize the heavy metals and brominated flame retardants. The mean and range of the results are 2207.7 μg/kg (503.9-11569.9 μg/kg) for Pb, 91.6 μg/kg (8.8-464.4 μg/kg) for Cd, 13.7 μg/kg (1.6-58.9 μg/kg) for Be, 7203.3 μg/kg (117-69813 μg/kg) for Sb, 471.3 μg/kg (143.4-2351.3 μg/kg) for As, 1.5 mg/kg (2.1-12.5 mg/kg) for Hg and 523.7 mg/kg (27.1-3859 mg/kg) for Cr. The BFRs - a sum Polybrominated Biphenyls, Polybrominated Diphenyl Ethers and Hexabromocyclododecane - were not detected except for two samples, which was an average of 234.5 μg/kg for nona-BDE and deca-BDE. The total bromine (Br) concentration varied from 0 to 471 mg/kg (average value of 87.9 mg/kg) , while Tetrabromobisphenol A (TBBP-A) showed an average concentration of 214.3 μg/kg. In the case of potential human health risks, Hg contributed the major risk for carcinogens and non-cancer disease in the plastics, but the contribution of Pb was also significant. In the case of eco-toxicity, Cr posed the most significant risks in the plastics. Overall, the results show that the toxic substances are below the limit values of substances regulated in the RoHS Directive in China and Europe. However, the results of LCIA highlight the growing importance to avoid the open burning practices of e-waste plastics that contain Hg, Pb, Cr ad Sb. Additionally, the results set a new database for the e-waste plastics recycling industry and provide information for ecodesign in EEE production.

Keywords: E-waste; Hazardous substances; Human health; Mobile phones; Plastics; Toxicity.