E-waste Dismantling Site Research Articles

Contamination characteristics and dietary intake risk of brominated flame retardants in fishes around a typical e-waste dismantling site in Southern China

Polybrominated diphenyl ethers (PBDEs) and their substitutes, novel brominated flame retardants (NBFRs), are ubiquitously present in the aquatic environment of electronic waste (e-waste) dismantling region, leading to their inevitable absorption and accumulation by aquatic organisms, which can be transferred to human via directly aquatic product consumption or through food chain, thereby posing potential health risks. This study focused on fish samples from Guiyu and its surrounding areas, and found the total PBDEs concentrations were 24–7400 ng/g lw (mean: 1800 ng/g lw) and the total NBFRs concentrations were 14 to 2300 ng/g lw (mean: 310 ng/g lw).Significant positive correlations were found among PBDE congeners, among different NBFRs, and between NBFRs and commercial PBDEs that they replace. ΣPBDEs and ΣNBFRs in the intestine were 620–350,000 and 91–81,000 ng/g lw (mean: 83000 and 12,000 ng/g lw, respectively), significantly exceeding those in the gills, where ΣPBDEs and ΣNBFRs were 14–37,000 and 39–45,000 ng/g lw (mean: 9200 and 2400 ng/g lw, respectively). The ΣPBDEs and ΣNBFRs showed no non-carcinogenic risks to the target population through dietary intake. Despite the significantly higher daily intake of decabromodiphenyl ethane (DBDPE) compared to decabromodiphenyl ether (BDE209), the non-carcinogenic risk associated with BDE209 remained higher than that of DBDPE. Our findings can assist researchers in understanding the presence of BFRs in aquatic organisms, inhabiting e-waste dismantling areas, and in evaluating the associated health risks posed to humans through dietary exposure.

Investigating the distribution of microplastics in soils from e-waste dismantling sites and their adsorption of heavy metals.

Microplastics are characterized by strong hydrophobicity, large specific surface area. In addition to the pollutant they contain, the heavy metals adsorbed on the surface of microplastics can migrate or be transformed with them into the environmental medium, which is potentially harmful to humans. The distribution characteristics of microplastics in contaminated soil at the e-waste dismantling site were studied. The study investigated the adsorption characteristics of polyvinyl chloride (PVC), polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) on copper (Cu), zinc (Zn) and lead (Pb). It analysed the influence of various factors on the adsorption process of heavy metals, the adsorption law of microplastics on some of the heavy metals in the environment, and the risk of heavy metal release from microplastics to soil. The results showed that ABS and PP were the main microplastics in the contaminated soil. Among them, black, white and transparent microplastics accounted for 89.91%. The shape of microplastics is mainly granular, and microplastics with a particle size of 1-2 mm accounted for the largest proportion. Further studies showed that plastic particles made of ABS, PP and PVC also have the adsorption capacity for different types of heavy metals in soil, and the trends of adsorption capacity are: PP>PVC>ABS. When PP does not reach adsorption equilibrium in the adsorption process, the smaller the particle size and the more added amount, the greater the adsorption capacity. This is because the smaller the particle size of the microplastic is, the more adsorption points it can provide, increasing its ability to adsorb heavy metal ions.

Lagging pollution of polycyclic aromatic hydrocarbons in the rebuilt e-waste site: From the perspective of characteristics, sources, and risk assessment

Little information is known regarding how the lagged pollution of polycyclic aromatic hydrocarbon (PAH) influenced the environment and human health after an e-waste dismantling site was rebuilt. This study investigated the characteristics, sources, and risk assessment of PAHs in a rebuilt e-waste site and its surrounding farmland by analyzing the samples of soil, dust, water, and vegetable. Concentrations of PAHs in soil, vegetable and water in the rebuilt site were relatively higher than in its surrounding farmland. The concentrations in surface soils, soil columns, dust, vegetables, and water varied from 55.4 to 3990 ng g−1, 1.65 to 5060 ng g−1, 2190 to 2420 ng g−1, 2670 to 10,300 ng g−1, and 46.8 to 110 μg L−1 in the e-waste site, respectively. On the farmland, PAH concentrations in surface soils, vegetables, and water ranged from 41.5 to 2760 ng g−1, 506 to 7640 ng g−1, and 56.6 to 89.2 μg L−1, respectively. A higher proportion of high-molecular-weight PAHs (HMW-PAHs) appeared in all multimedia compared with low-molecular-weight PAHs (LMW-PAHs). Diagnostic ratio together with positive matrix factorization (PMF) revealed that vehicle emission was the primary source in this area, and the activity of e-waste disposal was another important source in the rebuilt e-waste site. Based on the deterministic health risks, people working in the reconstructed e-waste site were exposed to low risks, whereas the residents living near the surrounding farmland were exposed to low risk. Sensitivity analyses indicated that exposure frequency and PAH concentrations were the main factors that influenced exposure risk. This study provides valuable insight into the comprehension of the lagging pollution effects of PAH on the environment and human health after the e-waste site was rebuilt.

Role of iron manganese plaque in the safe production of rice (Oryza sativa L.) grains: Field evidence at plot and regional scales in cadmium-contaminated paddy soils

The relationship between iron manganese plaque (IP) and cadmium (Cd) accumulation by rice in the microenvironment of rice rhizosphere at varying field scales needs to be further explored. In this study, we selected different rice varieties and implemented tailored amendments to ensure the safe production of rice grains in heavily Cd-contaminated farmland situated around an E-waste dismantling site. Through regional surveys, we elucidated the role of IP in facilitating safe rice production. The selection of low-Cd accumulating rice varieties and application of appropriate amendments with sufficient dosages allowed for the effective reduction of Cd transport from soil to rice, resulting in a safe concentration of Cd in rice grains. Analysis using a random forest algorithm indicated that iron (Fe) played a more pivotal role than manganese in soil–rice systems in mitigating Cd accumulation in brown rice. The presence of Fe in IP (IP-Fe) at a low loading mass was unfavorable to the Cd-safe production of rice, while at an IP-Fe loading mass of 52 g/kg, the Cd content in brown rice decreased to a safe level. Furthermore, precipitation, coprecipitation, and complexation of surface functional groups contributed to Cd fixation on IP, as indicated by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, electron probe microanalysis, and Fourier-transform infrared spectroscopy with attenuated total reflection. Our results highlighted the key role of IP in the production of Cd-safe rice at different field scales.

Emission characteristics of (halogenated) polycyclic aromatic hydrocarbons during printed circuit board combustion and estimated emission intensity of a typical e-waste dismantling site in South China

The pollution of polycyclic aromatic hydrocarbons (PAHs) and halogenated PAHs (Cl/Br-PAHs) caused by electronic waste dismantling activities have attracted considerable attention. The present study investigated the emissions and formation of PAHs and Cl/Br-PAHs based on the combustion of printed circuit boards simulating electronic waste dismantling process. The emission factor of ΣPAHs was 648 ± 56 ng/g, which was much lower than that of ΣCl/Br-PAHs (8.80 × 104 ± 9.14 × 103 ng/g). From 25 to 600 °C, the emission rate of ΣPAHs reached a sub-peak of 7.39 ± 1.85 ng/(g•min) at 350 °C, then increased gradually with the fastest rate of 19.9 ± 21.8 ng/(g•min) at 600 °C, whereas that of ΣCl/Br-PAHs was the fastest at 350 °C with a rate of 597 ± 106 ng/(g•min), then decreased gradually. The present study suggested that the formation pathways of PAHs and Cl/Br-PAHs are by de novo synthesis. Low molecular weight PAHs were readily partitioned into gas and particle phases, whereas high molecular weight fused PAHs were only detected in oil phase. However, the proportion of Cl/Br-PAHs in particle and oil phases were different from that of gas phase, whereas similar to that of the total emission. In addition, PAH and Cl/Br-PAH emission factors were used to estimate the emission intensity of pyrometallurgy project in Guiyu Circular Economy Industrial Park, and it was shown that approximately 1.30 kg PAHs and 176 kg Cl/Br-PAHs would be emitted annually. This study revealed that Cl/Br-PAHs would be formed by de novo synthesis, and for the first time provided the emission factors of Cl/Br-PAHs during the heat treatment process of printed circuit board, as well as estimated the contribution of pyrometallurgy, a new electronic waste recovery technology, to environmental Cl/Br-PAH pollution, which provides potential scientific information for governmental decision-making on the control of Cl/Br-PAHs.

First evidence of occupational and residential exposure to bisphenols associated with an e-waste dismantling site: A case study in China

Bisphenol A and its structural analogues (BPs) are widely used chemicals in electronics devices. To get insight into the occupational exposure to the full-time employees compared with the residents, urinary BPs in workers dismantling e-waste and in nearby residents were compared. Only 4 BPs among the tested 8 congeners, bisphenol AF (BPAF), bisphenol A, bisphenol S (BPS), and bisphenol F (BPF), were extensively detected with the detection frequencies of 100%, 99%, 98.7%, 51.3%. The median concentration of bisphenol A was 8.48 ng/mL, followed by BPAF (1.05 ng/mL), BPS (0.115 ng/mL), and BPF (0.110 ng/mL). The 4 detected BPs had a median concentration (Σ4BPs) ranging from 0.950 to 64.5 ng/mL in all volunteers, with a median value of 10.2 ng/mL. Result indicated the median concentration of ∑4BPs in worker’s urine was significantly higher (14.2 ng/mL) than those in residents in nearby towns (4.52 ng/mL and 5.37 ng/mL) (p < 0.05), suggesting a BPs’ occupational exposure risk related to e-waste dismantling. Besides, urinary ∑4BPs’ median concentrations for the employees in family workshops (14.5 ng/mL) were significantly higher than those in plants with centralized management (9.36 ng/mL). Among volunteers, higher ∑4BPs were observed in groups of aged above 50 years, males, or body weight under average with no significant correlations. The estimated daily intake of bisphenol A did not exceed the reference dose (50 μg/kg bw/day) recommended by the U.S. Food and Drug Administration. In this research, excess levels of BPs were recorded for the full-time employees in e-waste dismantling sites. Strengthened standards could support public health initiatives for full-time worker protection and reduce take-home BPs to family members.

Legacy and novel brominated flame retardants in a lab-constructed freshwater ecosystem: Distribution, bioaccumulation, and trophic transfer

The extensive utilization of both legacy and novel brominated flame retardants (BFRs) leads to high environmental concentrations, which would be bioaccumulated by organisms and further transferred through the food webs, causing potential risks to humans. In this study, five BFRs, that showed high detection frequencies and concentrations in sediments from an e-waste dismantling site in Southern China, namely 2,3,4,5,6-pentabromotoluene (PBT), hexabromobenzene (HBB), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), decabromodiphenyl ethane (DBDPE), and decabromodiphenyl ether (BDE209), were selected as target pollutants in the lab-constructed aquatic food web as part of a micro-ecosystem, to investigate their distribution, bioaccumulation, and trophic transfer patterns. The significant correlations between different samples in the food web indicated that the dietary uptake appeared to influence the levels of BFRs in organisms. Significant negative correlations were observed between the trophic level of organisms and the lipid-normalized concentrations of BTBPE and DBDPE, indicating the occurrence of trophic dilution after 5-month exposure. However, the average values of bioaccumulation factors (BAFs) were from 2.49 to 5.17 L/kg, underscoring the importance of continued concern for environmental risks of BFRs. The organisms occupying higher trophic levels with greater bioaccumulation capacities may play a pivotal role in determining the trophic magnification potentials of BFRs. This research provides a helpful reference for studying the impacts of feeding habits on bioaccumulation and biomagnification, as well as for identifying the fate of BFRs in aquatic environment.

The Spatial Distribution and Potential Risk Assessment of POPs in Farmland around a Typical E-Waste Dismantling Site.

Pollution from electronic-waste (E-waste) dismantling is of great concern. This study investigated the concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenyl ethers (PBDEs) in 253 cropland soil samples around an abandoned E-waste dismantling site in Taizhou city, Zhejiang province in China, using an analytical method which simultaneously extracted, purified and determined the identity and quantity of the three types of persistent organic pollutants. Meanwhile, their spatial distributions, pollution characteristics, and risk assessments were further analyzed. Total PCBs in the test soils ranged from below method detection limits (ND) to 2985.25μgkg-1 on a dry weight basis (d.w.), and the spatial distribution indicated a "hot spot" of PCBs pollution in the study area. The PAHs were detected in all samples with total concentrations ranging from 4.99 to 2723.06μgkg-1d.w. The distribution of PBDEs showed the pollution characteristics of "family-run workshops", with a total content range of ND ~ 899.34μgkg-1d.w., of which BDE209 was typically the dominant congener, accounting for 74.05% of the total PBDEs content in the test soils, with the highest content reaching 857.72μgkg-1d.w. Results showed that the ecological and lifetime carcinogenic risks of PCBs and PAHs were low in the study area, but the health risk caused by oral ingestion and dermal contact accounted for the highest proportion of the total exposure risks, while inhalation could be ignored. PBDEs in soils of the study area were a potential chronic non-carcinogenic risk, particularly for children. Therefore, in order to protect human health and environment, it is necessary to regulate the management of E-waste dismantling sites and pollution control.

Polybrominated diphenyl ethers and bromophenols in paired serum, hair, and urine samples of e-waste dismantlers: Insights into hair as an indicator of endogenous exposure

Polybrominated diphenyl ethers (PBDEs) are important pollutants during dismantling activities of electronic waste (e-waste) in China due to its large production and usage. Bromophenols (BPs), which are a kind of flame retardants and diphenyl ether bond cleavage metabolites of PBDEs, are often neglected in the assessment of human exposure to e-waste. Herein, 22 PBDEs and 19 BPs were determined in paired serum, hair, and urine samples collected from workers and residents of a typical e-waste dismantling site in southern China. Both PBDE and BP congeners were more frequently detected in hair than serum and urine samples. The medians of ΣPBDEs and ΣBPs were 350 and 547 ng/g dw in hair internal (hair-In) of occupational population, respectively, which were significantly higher than non-occupational population. However, a non-significant difference was found in levels of ΣPBDEs and ΣBPs in serum and urine between occupational and non-occupational populations, suggesting that hair analysis could easily differentiate between the exposure intensities of PBDEs and BPs to populations than serum and urine analyses. Moreover, levels of BPs in hair-In were 1–2 orders of magnitude higher than those in hair external (hair-Ex), while a non-significant difference was found in the levels of PBDEs. This result indicated that BPs might have originated from endogenous contribution. Notably, as the predominant congeners, the level of 2,4,6-tribromophenol (2,4,6-TBP) in hair-In was 3–8 times higher than that of BDE-209, while level of 2,4,6-TBP in hair-Ex was 1–3 times lower than that of BDE-209. Furthermore, in vivo experiments performed on Sprague–Dawley rats following a 28-day oral treatment with BDE-209 and 2,4,6-TBP verified that endogenous accumulation of 2,4,6-TBP in hair could be attributed to the metabolism of BDE-209 and exposure to 2,4,6-TBP. In conclusion, compared with PBDEs, biomonitoring phenolic compounds or metabolites with hair could better reflect human endogenous exposure.

The Typical Polybrominated Diphenyl Ethers (PBDEs) and Heavy Metals Distributions in a Formal e-Waste Dismantling Site.

Understanding the release of pollutants from the formal e-waste dismantling site could provide the basic information and potential risk to guide the normative regulation of the process. In this study, the distribution of typical polybrominated diphenyl ethers (PBDEs) and heavy metals in a relocating site of a formal e-waste dismantling company was firstly investigated down to the saturated zone, with a maximum depth of 3.0m. The mean concentrations of Σ13PBDEs were ranged from 2.815 to 7.178ng/g, with a peak value of 7.178ng/g in storage area. BDE-209 was the predominant congener of PBDEs in the soil, with the value ranged from 1.688 to 2.483ng/g. A higher pollution of PBDEs and HMs was presented in the storage area. The risk assessment of PBDEs mostly posed a low environmental risk (RQ ≤ 0.01) and pentaBDE was found to be the most harmful driver for the potential environmental risk.

Elevated levels of biomarkers of oxidative stress and renal injury linked to nitrogenous flame retardants exposure in e-waste dismantling site: A case study in China

Nitrogenous flame retardants (NFRs) have aroused worldwide public concern as their nephrotoxic effect. However, knowledge regarding the pathogenesis mechanism of their exposure to induce kidney injury remains largely unknown. In this study, eight NFRs, four oxidative stress biomarkers (OSBs), and one kidney injury biomarker, namely neutrophil gelatinase-associated lipocalin (NGAL), were measured in urine specimens collected from residents living around e-waste disassembly and reference areas, representing two exposure scenarios. Significant higher concentrations of Σ8NFR (median: 70.6 vs. 33.8 μg/g Cre) and five biomarkers (124 vs. 97.4 μg/g Cre) were found in urines of populations living in e-waste site compared to those in the reference site (p < 0.05). Primary NFRs exhibited significant positive associations with OSBs and NGAL regardless of the population examined, implying that chronic NFRs exposure could induce oxidative stress and kidney damage. By using structure equation model, we found that oxidative stress, particularly DNA and RNA oxidation mediated 16.1% of the total effect of NFRs on NGAL in e-waste related people, but not on the general population. Overall, this study suggests long-term chronic exposure to NFRs can induce oxidative stress and renal injury in humans but the pathogenesis mode may be scenario-specific.

Roseicella aerolata sp. nov., isolated from bioaerosols of electronic waste.

A novel Gram-stain-negative, non-motile, spherical-shaped and facultatively anaerobic bacterial strain, designated as GB24T was isolated from bioaerosols of an E-waste dismantling site in Guiyu, Guangdong Province, South PR China. Growth occurred at 15-40 °C (optimum 37 °C), pH 5.5-9.5 (optimum 7.0), and up to 0.5 % NaCl (w/v) under aerobic conditions, GB24T was characterized taxonomically and phylogenetically. The sole isoprenoid quinone detected was ubiquinone-10 (Q-10). The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, three unidentified glycolipids, one unidentified phospholipid, and one unidentified aminolipid. Carotenoid pigments were produced. The major cellular fatty acids (> 10 % of total fatty acids) were C17 : 1ω6c (51.5 %) and summed feature 8 (13.5 %, comprising C18 : 1ω7c and/or C18 : 1ω6c). Phylogenetic analysis based on 16S rRNA gene sequence and draft genome grouped strain GB24T into the genus Roseicella. GB24T was most closely related to Roseicella frigidaeris DB1506T with 97.5 % 16S rRNA gene sequence similarity. The draft genome of GB24T comprised 6 153 170 bp with a DNA G+C content of 71.5 %. The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between GB24T and DB1506T were 83.2 % (Ortho ANI), 83.3 % [ANI by blast (ANIb)] and 27.0 %, respectively. Further genomic analysis of GB24T revealed the secondary metabolite clusters of terpene and phosphonate, which indicate the capacity for malleobactin (14 %) and phosphinothricin (6 %) tripeptide production. On the basis of the genotypic, chemotaxonomic and phenotypic results, GB24T represents a novel species, for which the name Roseicella aerolata sp. nov. is proposed. The type strain of Roseicella aerolata is GB24T (= GDMCC 1.2169T = JCM 34449T).

First Evidence of Prenatal Exposure to Emerging Poly- and Perfluoroalkyl Substances Associated with E-Waste Dismantling: Chemical Structure-Based Placental Transfer and Health Risks.

Limited information is available about prenatal exposure to per- and polyfluoroalkyl substances (PFAS) in electronic waste (e-waste) recycling sites. In this study, we determined 21 emerging PFAS and 13 legacy PFAS in 94 paired maternal and cord serum samples collected from an e-waste dismantling site in Southern China. We found 6:2 fluorotelomer sulfonate (6:2 FTSA), 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), and perfluorooctanephosphonate (PFOPA) as the major emerging PFAS, regardless of matrices, at median concentrations of 2.40, 1.78, and 0.69 ng/mL, respectively, in maternal serum samples, and 2.30, 0.73, and 0.72 ng/mL, respectively, in cord serum samples. Our results provide evidence that e-waste dismantling activities contribute to human exposure to 6:2 FTSA, 6:2 Cl-PFESA, and PFOPA. The trans-placental transfer efficiencies of emerging PFAS (0.42-0.94) were higher than that of perfluorooctanesulfonic acid (0.37) and were structure-dependent. The substitution of fluorine with chlorine or hydrogen and/or hydrophilic functional groups may alter trans-placental transfer efficiencies. Multiple linear regression analysis indicated significant associations between maternal serum concentrations of emerging PFAS and maternal clinical parameters, especially liver function and erythrocyte-related biomarkers. This study provides new insights into prenatal exposure to multiple PFAS in e-waste dismantling areas and the prevalence of emerging PFAS in people living near the sites.

Distribution characteristics and risks assessment of brominated flame retardants in surface soil from both a legacy and a new e-waste dismantling site

Brominated flame retardants (BFRs) are widely used in diverse industries, resulting in extensive environmental contamination. Although many legacy BFRs have been banned and replaced with novel brominated flame retardants (NBFRs), these NBFRs have also been found to exhibit toxicity and persistence. In this study, 55 soil samples were collected from areas surrounding an abandoned (FJ) and a newly built (TZ) e-waste dismantling zone which represent the traditional and modern e-waste dismantling practice in China, respectively, to examine and compare the occurrence of BFRs and their potential ecological and health risks. The concentrations of novel brominated flame retardants (NBFRs) ranged from 10.0 to 2,390 ng/g dw, and those of polybrominated diphenyl ethers (PBDEs) ranged from 78.0 to 13,300 ng/g dw. Decabromodiphenyl ethane (DBDPE) to BDE-209 ratios were greater than one in 6.8% and 25% of samples in FJ and TZ, respectively. BFRs concentrations in FJ soils significantly decreased with increasing distance to the center of FJ, indicating that the soil in the FJ region was strongly affected by the e-waste dismantling activities in FJ. For TZ, only DBDPE exhibited similar regulation, indicating that the newly built e-waste dismantling zone has already impacted on the surrounding environment. The Mann–Whitney test showed that the concentrations of most PBDE congeners were higher in FJ (P < 0.01/0.05) than those in TZ, while there was no significant difference in the concentrations of most NBFRs between FJ and TZ. A low abundance of BDE-209 in soils suggests that its degradation process and DBDPE was the predominant NBFRs in soils from both FJ and TZ. It was found that low-brominated PBDE congeners posed high ecological risks to terrestrial animals, which the ecological risks may increase in the future due to the debromination process of high PBDE congeners. The health hazard of BFRs via soil exposure in FJ was generally higher than in TZ, although both were acceptable. Despite much greater average daily doses for BDE-209 and DBDPE, the oral hazard quotients of BDE-47 and BDE-99 were much higher. Toddlers were found to face a higher health risk due to soil exposure than teenagers and children. The carcinogenic effect of BDE-209 was also acceptable in FJ and TZ. With the continuous operation of the TZ site, the further accumulation of BFRs in soils and health hazard via BFRs exposure are expected, and the results suggest that ongoing monitoring and further research is necessary. We believe that our work could help researchers investigate and reveal the harmful impacts of NBFRs and PBDEs.

Exposure, risk and predictors of hexabromocyclododecane and Tetrabromobisphenol-A in house dust from urban, rural and E-waste dismantling sites in Thailand.

In this study, for the first time, we determined concentrations of hexabromocyclododecane (HBCDD) and tetrabromobisphenol-A (TBBPA) in house dust and estimated human exposure to these substances in houses located in an e-waste dismantling site and in urban and rural residential areas of Thailand. The median HBCDD concentration in urban residential houses (2.10ngg-1) was similar to that in houses in an e-waste dismantling site (2.05ngg-1, p>0.05) and slightly higher than that in rural residential houses (1.11ngg-1, p>0.05). In contrast, significantly higher TBBPA concentrations were present in house dust from an e-waste dismantling site (median=720ngg-1; range=44-2300ngg-1) compared to those in urban (68.6ngg-1; 3.5-300ngg-1, p<0.001) and rural residential areas (17ngg-1; 2.0-201ngg-1, p<0.001). TBBPA concentrations increased with the increasing presence of electronic devices and a decreasing distance to the e-waste dismantling site. These results suggest that e-waste dismantling activities may contribute to TBBPA contamination of house dust. The median estimated daily intake (EDI) of HBCDD and TBBPA through dust ingestion for toddlers exceeded that for children and adults. However, EDI values for HBCDD and TBBPA from all age groups were below the oral reference dose guideline value suggested by the US National Research Council and National Toxicology Program (NTP).

Ecological and human health risk assessment of heavy metals based on their source apportionment in cropland soils around an e-waste dismantling site, Southeast China

An accurate understanding of soil heavy metal (HM) pollution characteristics and source apportionment, and a recognition of the major factors influencing ecological and human health risks (HHRs) are essential for soil HM pollution control and remediation. In this study, 212 surface soils (0–20 cm) and 15 profile soils (0–100 cm) were collected from cropland soils around an e-waste dismantling site in Taizhou city, Zhejiang Province, China. Spatial analysis was used to evaluate the pollution characteristics of HMs (Cd, Cu, Pb, Zn, Cr and Ni). Principal component analysis (PCA) and positive matrix factorization (PMF) were also conducted to quantify their source contributions. A modified source-oriented HHR assessment integrated source-oriented ecological risk and source-oriented HHR assessment was developed to describe the major factors that influenced HHR. Results showed that 94.81 %, 88.21 %, 36.79 % and 47.17 % of Cd, Cu, Pb and Zn, respectively, in surface soils exceeded their screening values in the soil environmental quality standard for agricultural soils (GB 15618–2018). Spatial analysis indicated that high values of Cd, Cu, Pb and Zn were distributed near the e-waste dismantling site. The results of PCA and PMF showed that the primary sources of HMs in the study area are e-waste dismantling activities, natural sources and atmospheric deposition, which contribute 27 %, 46 % and 27 % of HM pollutants, respectively. The results of source-oriented ecological risk and HHR assessment indicated that e-waste dismantling activities and natural sources were primary sources for ecological risk and HHR. However, source-oriented HHR assessment may underestimate the contribution of e-waste dismantling activities by ignoring HM pollution levels. The modified source-oriented HHR assessment highlights that e-waste dismantling activities were major factor that affect noncarcinogenic risk. This study could provide important data support for subsequent environmental remediation of soil HM pollution in cropland soils around e-waste dismantling sites.

Effects of soil-extractable metals Cd and Ni from an e-waste dismantling site on human colonic epithelial cells Caco-2: Mechanisms and implications

E-wastes release toxic metals including Cd, Cu, Ni, Pb and Zn into nearby soils during dismantling process. However, their adverse effects and the associated mechanisms on human intestinal epithelium are poorly understood. In this study, their toxic effects on human colonic epithelial cells Caco-2 and the underlying mechanisms were assessed basing on three soils from Wenling e-waste dismantling site. Since soil-extractable metals are more available for gastrointestinal absorption, we used phosphate buffer saline solution to extract metals at solid to liquid ratio of 1:2. Among metals, total Cd and Ni exceeded the risk screening values in three soils, being 3.8–8.8 and 42.4–155 mg/kg. Furthermore, high extractable-metals at 5.9, 1.9, and 0.87 mg/kg Cd (20–67%) and 4.6, 6.4, and 12.4 mg/kg Ni (3.6–29%) were observed for Soil-1, -2 and -3, respectively. All three extracts triggered cytotoxicity, with Soil-2 showing the strongest inhibition of cell viability. Higher production of reactive oxygen species and stronger inhibition of antioxidant enzymes SOD1 and CAT were observed in Soil-2 and -3. Upregulation of proinflammatory mediators (IL-1β, IL-8 and TNF-α) and apoptosis-regulatory genes (GADD45α, Caspase-3, and Caspase-8) were observed. Our data suggest that soil extracts induced cytotoxicity, oxidative damage, inflammatory response, and cell apoptosis in Caco-2 cells, indicating soil ingestion from e-waste dismantling site may adversely impact human health.

Identifying Dermal Uptake as a Significant Pathway for Human Exposure to Typical Semivolatile Organic Compounds in an E-Waste Dismantling Site: The Relationship of Contaminant Levels in Handwipes and Urine Metabolites.

Dermal exposure to semivolatile organic compounds (SVOCs) has recently attracted widespread attention; understanding these exposures is particularly important for people whose skin is frequently exposed to different pollution surfaces. In this study, handwipes were collected from exposed occupational workers and local residents near a typical electronic waste (e-waste) dismantling area; urine samples were also sampled. The wipes were analyzed for three typical SVOCs: polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), and organophosphate flame retardants (OPFRs). The median levels of PAHs, OPFRs, and PBDEs in handwipes from e-waste dismantlers were 96.0, 183, and 238 ng, respectively. The analytes were higher in the handwipes collected from workers than those from residents, indicating that they were subjected to greater dermal exposure during primitive e-waste dismantling activities. Among the three SVOCs, the strongest correlation was found between triphenyl phosphate (TPhP) in handwipes and diphenyl phosphate (DPhP) in paired urine; the next strongest correlations were between PAHs and PBDEs and their corresponding urinary metabolites. The results showed that TPhP contributed the highest exposure to e-waste dismantlers via dermal exposure. Our research highlights the importance of dermal exposure to TPhP, which should be considered in future exposure risk assessments.

Strategies of cadmium and copper uptake and translocation in different plant species growing near an E-waste dismantling site at Wenling, China.

This study aimed to explore the interactions between cadmium (Cd) and copper (Cu) during uptake and translocation in plants growing in soil polluted with heavy metals derived from electronic waste (E-waste). We collected the roots, stems, leaves, and root-surrounding soils of ten dominant plant species growing in farmland near an E-waste dismantling site, and analyzed their Cd and Cu concentrations. Among the ten plant species, Echinochloa crus-galli (L.) P. Beauv., Cucurbita moschata (Duch. ex Lam.) Duch. ex Poiret, Phragmites australis (Cav.) Trin. ex Steud., and Benincasa hispida (Thunb.) Cogn. accumulated Cd (2.40-4.56 mg kg-1) and Cu (19.60-35.21 mg kg-1) in the roots. In Polygonum hydropiper L. and Sesbania cannabina (Retz.) Poir., the Cd (0.50-0.81 mg kg-1) and Cu (11.04-15.55 mg kg-1) concentrations were similar among the three organs. Glycine max (L.) Merr. accumulated more Cu in the roots (16.42 mg kg-1) than in the stems (5.61 mg kg-1) and leaves (7.75 mg kg-1), and accumulated Cd at similar levels in the three organs (0.65-0.99 mg kg-1). Sesamum indicum L., Bidens pilosa L., and Solidago decurrens Lour. accumulated Cd at similar levels among the three organs (0.16-3.34 mg kg-1) and accumulated less Cu in the stems (6.89-8.28 mg kg-1) than in the roots (12.61-21.63 mg kg-1) and leaves (12.93-22.38 mg kg-1). S. indicum had a stronger capacity to accumulate and translocate Cd and Cu according to transfer coefficient and translocation factor. The concentrations of Cd and Cu in soils were significantly positively correlated with those in the roots (p<0.01) but not those in the stems and leaves. We detected significantly positive correlations between Cd and Cu concentrations in the roots and leaves (p<0.01) but not in the stems. These results suggest that there is a synergetic strategy of Cd and Cu transport from soils to the roots and from the roots to the leaves, while the stems may not be the key organ controlling Cd and Cu transport in plants. These findings have important implications for the phytoremediation of soils contaminated with Cd and Cu, the mechanisms of plant Cd and Cu transport, and the food safety of agricultural products.

Environmental Effects of Heavy Metals from the E-Waste Dismantling Site, South China

ABSTRACT E-waste dismantling activities have caused serious heavy metals pollution in some parts of China. In this study, the contents of 15 metals (Ag, As, Cd, Co, Cr, Cu, Li, Mn, Ni, Pb, Rb, Sb, Sn, Tl, and Zn) in soil, sediment, and water hyacinth derived from the e-waste dismantling activities were investigated. Based on these data, the Geo-accumulation index (Igeo) and the potential ecological risk index (RI) were used to assess potential ecological risk. The results showed that the concentration of As, Cd, Cu, Sb, Sn, and Zn in soil for 6.4–131, 0.09–11.2, 25.5–5900, 3.7–443, 5.7–272, and 39–2040 mg kg−1, which the average content exceeded the natural background levels for 5.6, 57, 87, 142.7, 16.7 and 12.7 times, respectively. The concentration of Cu, Sb, Sn, and Zn in sediment for 41.2–468.3, 2.59–33.83, 10.3–92.9, and 148–502.7 mg kg−1, respectively, which the average content exceeded the natural background levels for 14.7, 20.9, 7.1, and 5.7 times, respectively. The Igeo indicated that soil and sediment at sites where e-waste was still heavily contaminated with a variety of heavy metals (such as Cd, Cu, Pb, Sb, Sn, and Zn), which were obvious accumulation effects. The RI in the surface of sediment indicated the average ecological risk of As, Cd, Co, and Cu was high risk and the total risk reached a very high risk at each sampling site. Water hyacinth has strong ability to enrich heavy metals. We suggest that the heavy metals in soil and sediment should be periodically monitored, especially Cd, Cu, Pb, Sb, Sn, and Zn. Water hyacinth can be used to monitor these heavy metals contaminated in river. The cleaning up of the soil and sediment should be a priority for any future remediation program in the study area.