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Flame retardants (FRs) from electronic waste (e-waste) are a widespread environmental concern. In our study, in vitro physiologically based extraction tests (PBETs) for FRs were conducted in three different areas where dust remained after processing of e-waste to identify the bioaccessible FRs and quantify their bioaccessibilities of gastrointestinal tract for human as well as to assess the exposure via ingestion of workers in e-waste processing workshops. All 36 FRs were measured and detected in indoor dusts. Among the FRs, the mean concentrations of polybrominated diphenyl ethers (PBDEs) in the floor dust and settled dust were highest, 65,000 ng/g, and 31,000 ng/g, respectively. In contrast, phosphorus-containing flame retardants (PFRs) presented the highest mean concentration in the workplace dust samples, 64,000 ng/g. However, the highest bioaccessible concentrations in workplace dust, floor dust, and settled dust were observed for PFRs: 5900, 1600, and 680 ng/g, respectively. This study revealed that the higher bioaccessibility of PFRs versus other compounds was related to the negative correlation between FR concentrations and log KOW (hydrophobicity) values. The fact that hazard indices calculated using measured bioaccessibilities were less than 1 suggested that the non-cancer risk to human health by the FRs exposure via dust ingestion might be low.

In developing countries, inappropriate recycling of e-waste has resulted in the environmental release of toxicants, including heavy metals, that may have deleterious health effects. In this study, we estimated daily metal intakes in five households in a Vietnamese village located in an e-waste processing area and assessed the health risk posed by exposure to the metals. Garden soil, floor dust, 24-h duplicate diet, and ambient air samples were collected from five households in northern Vietnam in January 2014. All samples were acid-digested, and contents of Cd, Cu, Mn, Pb, Sb, and Zn were measured by using ICP mass spectrometry and ICP atomic emission spectroscopy. In addition, the soil, dust, and diet samples were subjected to an bioaccessibility extraction test to determine bioaccessible metal concentrations. Hazard quotients were estimated from bioaccessible metal concentrations, provisional tolerable weekly intakes, and reference doses. Garden soil and floor dust were estimated to be mainly contributors to daily Pb intake, as indicated by calculations using bioaccessible metal concentrations and the U.S. Environmental Protection Agency soil plus dust ingestion rate. Diet was suggested to contribute significantly to daily Cd, Cu, Mn, Sb, and Zn intake. Estimated metal exposures via inhalation were negligible, as indicated by calculations using International Atomic Energy Agency reference inhalation rates. The maximum hazard quotients were calculated as 0.2 (Cd), 0.09 (Cu), 0.3 (Mn), 0.6 (Pb), 0.2 (Sb), and 0.5 (Zn), on the basis of bioaccessible metal concentrations. The contributions of Cd, Cu, Mn, Sb, and Zn except Pb to potential noncancer risk for adult residents of the five households in the e-waste processing area may be low.

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

We investigated the concentrations of polybrominated diphenyl ethers (PBDEs) and alternative flame retardants (FRs) in environmental samples collected in January 2012, 2013, and 2014 from an electronic waste-processing area in northern Vietnam. During the study period, PBDE and alternative FR concentrations in soils around the electronic waste-processing workshops ranged from 37 to 9200 ng g −1 dry weight (dw) and from 35 to 24,000 ng g −1 dw; the concentrations in soils around the open-burning sites ranged from 1.6 to 62 ng g −1 dw and from −1 dw; and the concentrations in river sediments around the workshops ranged from 100 to 3800 ng g −1 dw and from 23 to 6800 ng g −1 dw, respectively. Over the course of study period, we observed significant decreases in concentrations of PBDEs and significant increases in concentrations of alternative FRs, particularly Dechlorane Plus isomers and oligomeric organophosphorus FRs ( o -PFRs) in both soils and sediments around the workshops. We also report information on concentrations and environmental emissions of o -PFRs and their low-molecular-weight impurities in the same soils and sediments. The detection of o -PFR impurities around the workshops and the open-burning sites highlights an enhanced breakdown of o -PFRs probably due to weathering during open storage and high temperature attained during the burning of electronic wastes.

Although bioaccessibility testing is applied worldwide for appropriate chemical risk assessment, few studies have focused on the bioaccessibility of flame retardants (FRs), especially inhalation exposure. This study assessed inhalation exposure to FRs in indoor dust by workers at e-waste-dismantling workshops in northern Vietnam, by using modified simulated epithelial lung fluid (SELF) and artificial lysosomal fluid (ALF). The average mass concentrations of FRs were 130,000 ng/g for workplace dust (n = 3), 140,000 ng/g for floor dust (n = 3), and 74,000 ng/g for settled dust (n = 2), whereas the average bioaccessible concentrations of FRs were 1900, 1400, and 270 ng/g in the SELF condition and 2600, 770, and 490 ng/g in the ALF condition, respectively. Results clearly indicate that the bioaccessible concentrations of FRs are markedly lower than their mass concentrations. Tris(2-chloroethyl) phosphate (TCEP, ~19%), tris(2-chloroisopropyl) phosphate (TCIPP, ~35%), and tris(1,3-dichloroisopropyl) phosphate (TDCIPP, ~22%) showed comparably high bioaccessibility in both SELF and ALF conditions. In contrast, the bioaccessibility of tetrabromobisphenol A (TBBPA, ~20%) was high in the SELF condition, but not in the ALF condition. With regard to the test compounds' physicochemical properties, the inhalation bioaccessibility of FRs in both conditions increased as molecular weight or octanol–water partition coefficient decreased, and it decreased as water solubility decreased. Health risk assessment clearly indicated that the hazard quotient of FRs via inhalation exposure for workers in the e-waste-dismantling workshops was less than 1, suggesting that the inhalation exposure to FRs during indoor dismantling of e-waste at this site was negligible based on the current methodology of non-cancer health risk assessment used in this study.

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