Wednesday, April 24, 2019

Scientists Find Hidden Dioxins In African E-Waste Hubs

Electronic waste (e-waste) is a source of harmful dioxins in Africa, according to research by Japanese scientists. They published their results in the journal Environmental Science & Technology. E-waste refers to end-of-life products such as communication devices, consumer electronics and home appliances. Due to the presence of toxic substances such as heavy metals and many various plastic additives in e-waste, the discarded materials are considered hazardous and must be handled properly. Yet, a large volume of e-waste has been recycled inappropriately and treated informally in Asian and African developing countries. Primitive methods such as circuit board heating and open burning of wires have thus led to serious environmental pollution, caused by the emission of not only contaminants contained in e-waste, but also unintentionally-formed secondary toxic chemicals. In this study, researchers led by Professor Tatsuya Kunisue of Ehime University, Japan, found dioxins—a toxic substance generated during informal processing of e-waste—in soils from the Agbogbloshie e-waste site in Ghana. The researchers used analytical methods based on two-dimensional gas chromatography and time-of-flight mass spectrometry to profile halogenated contaminants in the soils collected near e-waste burning and dismantling areas. They identified polybrominated and mixed halogenated dibenzofurans (PBDFs and PXDFs) as the major dioxin. PBDFs were generated from a group of flame retardants commonly found in e-waste plastics. On the other hand, PXDFs were mainly produced from PBDFs through successive bromine-to-chlorine exchange, said the researchers. High concentrations of PXDFs in e-waste burning areas indicate that these ‘hidden’ dioxins may contribute substantially to the total toxicity of the e-waste-derived dioxin mixture, and need to be included in future environmental and human exposure risk assessment. 
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