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Inappropriate e-waste-processing operation is a serious issue in developing countries since the early 2000's. Field research was conducted to clarify its influences and diffuse toxic substances in the environment at e-waste-processing sites in a village in northern Vietnam from 2012 to 2014. We investigated surface soil samples collected from e-waste-processing sites, open burning sites, and rice paddy sites. Sediment samples and water samples were also collected from a river that runs through the village. The hazardous metal concentration in soil and river sediment samples indicated that 7 elements (Ca, Cu, Mo, Ni, Pb, Sn, and Zn) had high concentrations as a result of e-waste-processing. Most notably, Pb and Cu had high concentrations in soil samples (Pb: 26–2200 mg/kg, Cu: 22–3000 mg/kg). The results of a multivariate analysis indicated that these 7 elements were closely correlated with e-waste-processing. Concentrations of hazardous metals showed an upward trend where e-waste-processing occurred during the 3-year study period, although it was not significant statistically at present. Open burning activity had a great influence on Cu accumulation, and maximum Cu concentrations increased from 340 mg/kg in 2012–3000 mg/kg in 2014 in soil samples from open-burning sites. There were large differences in the dominant hazardous metal depending on the type of e-waste-processing workshop because hazardous metal composition was influenced by the types of e-waste and the processing procedures. It is necessary to avoid e-waste processing in open-air environment to control emissions of hazardous substances. Especially, open burning should be prohibited. Keywords: E-waste-processing, Open burning, Soil pollution, Hazardous metal

The management of electronic waste (e-waste), which can be a source of both useful materials and toxic substances, depending on the processing method, is important for promoting material cycling. In this study, we used the dioxin-responsive chemical-activated luciferase gene expression (DR-CALUX) assay combined with gas chromatography–high-resolution mass spectrometry to evaluate the levels of dioxin-like compounds in surface soils and river sediments collected in and around an e-waste-processing village in northern Vietnam. The WHO-TEQs (Toxic equivalents) of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), coplanar polychlorinated biphenyls (Co-PCBs), and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in soils collected in January 2012 ranged from 0.29 to 310 pg/g (median 2.9 pg/g, n = 32), and the WHO-TEQs in sediments ranged from 0.96 to 58 pg/g (median 4.4 pg/g, n = 8). Dioxin-like activities (CALUX-TEQs [2,3,7,8-TCDD equivalent]) in soils collected in January 2012, 2013, and 2014 ranged from