Environmental pollution and human body burden from improper recycling of e-waste in China: A short-review

Ecotoxicological assessment, oxidative response, and enzyme activity disorder of the rotifer Brachionus asplanchnoidis exposed to a toxic cocktail of spent lithium-ion battery leachate

Spent lithium-ion batteries (LIBs) have emerged as a major source of waste due to their low recovery rate. The physical disposal of spent LIBs can lead to the leaching of their contents into the surrounding environment. While it is widely agreed that hazardous substances such as nickel and cobalt in the leachate can pose a threat to the environment and human health, the overall composition and toxicity of LIB leachate remain unclear. In this study, a chemical analysis of leachate from spent LIBs was conducted to identify its primary constituents. The ecotoxicological parameters of the model organism, rotifer Brachionus asplanchnoidis, were assessed to elucidate the toxicity of the LIB leachate. Subsequent experiments elucidated the impacts of the LIB leachate and its representative components on the malondialdehyde (MDA) level, antioxidant capacity, and enzyme activity of B. asplanchnoidis. The results indicate that both the LIB leachate and its components are harmful to individual rotifers due to the adverse effects of stress-induced disturbances in biochemical indicators, posing a threat to population development. The intensified poisoning phenomenon under combined stress suggests the presence of complex synergistic effects among the components of LIB leachate. Due to the likely environmental and biological hazards, LIBs should be strictly managed after disposal. Additionally, more economical and eco-friendly recycling and treatment technologies need to be developed and commercialized.

Sustainable resilient E-waste management in London: A circular economy perspective

The circular economy (CE) is reasoned to organize complex systems supporting sustainable resilience by distinguishing between waste materials and economic growth. This is crucial to the electronic waste (e-waste) industry of developed countries, and e-waste operation management has become their top priority because e-waste contains toxic materials and valuable sources of elements. In the UK, although London Metropolitan city boasts an ambitious sustainable resilience target underlying the context of CE, practical implementation has yet to be feasible, with few investigations detailing if and how the existing target implications enable industrial and social-ecological sectors to continue their performance functionalities in the face of undesired disruptions. In this paper, a dynamic Bayesian Network (dynamic BN) approach is developed to address a range of potential risks. The existing London e-waste operation management is considered as an application of study for sustainable resilience development. Through the utilization of dynamic BN, a comprehensive analysis yields a Resilience Index (RI) of 0.5424, coupled with a StdDev of 0.01350. These metrics offer a profound insight into the intricate workings of a sustainable system and its capacity to swiftly rebound from unexpected shocks and disturbances. This newfound understanding equips policymakers with the knowledge needed to navigate the complexities of sustainable e-waste management effectively. The implications drawn from these in-depth analyses furnish policymakers with invaluable information, enabling them to make judicious decisions that advance the cause of sustainable e-waste management. The findings underscore that the absorptive capacity of a sustainable and resilient e-waste operation management system stands as the foremost defense mechanism against unforeseen challenges. Furthermore, it becomes evident that two pivotal factors, namely "diversifying the supply chain" and "enhancing supply chain transparency," play pivotal roles in augmenting the sustainability and resilience of e-waste operation management within the context of London's ambitious sustainability targets. These factors are instrumental in steering the trajectory of e-waste management towards a more sustainable and resilient future, aligning with London's aspirations for a greener and more eco-conscious future.

Cuproptosis is involved in decabromodiphenyl ether-induced ovarian dysfunction and the protective effect of melatonin

Decabromodiphenyl ether (BDE-209) has been universally detected in environmental media and animals, but its damage to ovarian function and mechanism is still unclear, and melatonin has been shown to improve mammalian ovarian function. This study aimed to investigate the toxic effects of BDE-209 on the ovary and tried to improve ovarian function with melatonin. Herein, BDE-209 was administered orally to female SD rats for 60 days. Enzyme-linked immunosorbent assay, HE staining, transcriptome analysis, qPCR and immunohistochemical staining were used to explore and verify the potential mechanism. We found that BDE-209 exposure had effects on the ovary, as shown by abnormal changes in the estrous cycle, hormone levels and ovarian reserve function in rats, while increasing the proportion of collagen fibres in ovarian tissue. In terms of mechanism, cuproptosis, a form of cell death, was identified to play a crucial role in BDE-209-induced ovarian dysfunction, with the phenotype manifested as copper salt accumulation in ovary, downregulation of glutathione pathway metabolism and copper transfer molecule (ATP7A/B), and upregulation of FDX1, lipoic acid pathway (LIAS, LIPT1), pyruvate dehydrogenase complex components (DLAT, PDHB, PDHA1), and copper transfer molecule (SLC31A1). Furthermore, possible interventions were explored. Notably, a supplement with melatonin has a repair effect on the damage to ovarian function by reversing the gene expression of cuproptosis-involved molecules. Overall, this study revealed that cuproptosis is involved in BDE-209-induced ovarian damage and the beneficial effect of melatonin on ovarian copper damage, providing evidence for the prevention and control of female reproductive damage induced by BDE-209.

Concentrations and influencing factors of 17 elements in placenta, cord blood, and maternal blood of women from an e-waste recycling area

BACKGROUND

The effects of prenatal element exposure on mothers and fetuses have generated concern. Profiles of trace and toxic elements in biological material are urgently desired, especially for women who reside near e-waste recycling facilities. The aim of this study was to investigate elements concentrations in placenta, cord blood, and maternal blood of women and to evaluate the influencing factors.

METHODS

A group of 48 women from an e-waste recycling site and a group of 31 women from a non-e-waste recycling site were recruited. Basic characteristics were collected by questionnaire and the concentrations of 17 elements in placenta, cord blood, and maternal blood samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Finally, the generalized linear model regression analysis (GLM) was used to test the association between element concentrations and possible factors.

RESULTS

Compared to the control group, the exposed group had significantly elevated cadmium (Cd), zinc (Zn), nickel (Ni), and antimony (Sb) in placenta, and higher lead (Pb) in maternal blood and cord blood (P<0.05). Sb concentration in maternal blood was significantly lower than in the control group (P<0.05). GLM analysis showed that element concentrations were mainly associated with maternal age [chromium (Cr), iron (Fe), selenium (Se), cobalt (Co), mercury (Hg) in placenta, copper (Cu) in maternal blood], education (Se, Sb in placenta), family income (Cu in maternal blood and Ni in placenta), passive smoking [Cu and Zn in placenta, Pb in maternal blood], and e-waste contact history (Hg in cord blood, Cu, Zn, and Cd in maternal blood).

CONCLUSIONS

Women in the e-waste recycling area had higher toxic element levels in the placenta and blood samples. More preventive measures were needed to reduce the risk of element exposure for mothers and fetuses in these areas.

Photochemical behaviour and toxicity evolution of phenylbenzoate liquid crystal monomers in water

Liquid crystal monomers (LCMs) are a group of emerging pollutants that pose potential environmental risks because of their ubiquitous occurrence and toxicity. Understanding their environmental transformation is essential for assessing the ecological risk. In this study, we investigated the photochemical transformation kinetics, mechanism, and photo-induced toxicity of three phenylbenzoate LCMs in water. Their apparent photolytic rate constants were within (0.023 - 0.058) min-1, and the half-lives were < 30.0 min, showing lower persistence in water. Dissolved organic matter significantly inhibited their photolysis because of light-shielding effect and quenching of excited triplet states of LCMs. Their photolysis mainly occurred through excited triplet states, and the reactive oxygen species (i.e., ⋅OH, 1O2 and ⋅O2-) contributed to their degradation. The main photolysis pathways were ester bond cleavage, ⋅OH substitution/addition, and defluorination. Experiments and computational simulation revealed that some ·OH addition/substitution products have similar toxicity with LCMs. Additionally, the ∙OH reaction rate constants (kOH) of LCMs were determined to be > 1 × 109 M-1 s-1, evidence for their high reactivity toward ⋅OH. We have further developed reliable methods to estimate kOH of other phenylbenzoate-like LCMs with quantum chemical calculations. These results are useful for understanding the transformation and fate of LCMs in aquatic environments.

A comprehensive assessment of external exposure to persistent halogenated organic pollutants for residents in an e-waste recycling site, South China

Human skin wipes from 30 participants, air, dust, and food items were collected from a former electronic waste site in South China to provide a comprehensive understanding of residents' exposure to halogenated flame retardants (HFRs) and polychlorinated biphenyls (PCBs). The total concentration of halogenated organic pollutants (HOPs) in the dust, air, food and skin wipes ranged 240-25000 ng/g, 130-2500 pg/m3, 0.08-590 ng/g wet weight, and 69-28000 ng/m2, respectively. Wild fish, vegetables, and air were dominated by PCBs, whereas dust, livestock, and poultry were dominated by HFRs. The HOP concentrations were several orders of magnitude higher in local foodstuffs than in market foodstuffs. The chemical composition on the forehead was remarkably different from that on the hand. The importance of different exposure routes depends on the residents' food choices, except decabromodiphenyl ethane (DBDPE). For residents who consumed a 100-foot diet (mainly egg) and local wild fish, diet ingestion overwhelmed other exposure routes, and PCBs were mainly contributed by fish and HFRs by egg. For residents who consumed market food, the dermal absorption of most PCB congeners and dust ingestion of highly brominated flame retardants were relatively prominent. Inhalation was found to be a crucial route for pentabromoethylbenzene (PBEB).

Assessment of legacy and alternative halogenated organic pollutants in outdoor dust and soil from e-waste sites in Nigeria: Concentrations, patterns, and implications for human exposure

E-waste is often processed informally, particularly in developing countries, resulting in the release of harmful chemicals into the environment. This study investigated the co-occurrence of selected persistent organic pollutants (POPs), including legacy and alternative halogenated flame retardants (10 polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), syn and anti-dechlorane plus (DP)), 32 polychlorinated biphenyls (PCBs) and 12 organochlorine pesticides (OCPs), in 20 outdoor dust and 49 soil samples from 7 e-waste sites in Nigeria. This study provides the first report on alternative flame retardants (DBDPE and DP) in Nigeria. The total concentration range of the selected classes of compounds was in the order: ∑10PBDEs (44-12300 ng/g) > DBDPE (4.9-3032 ng/g) > ∑2DP (0.7-278 ng/g) > ∑32PCBs (4.9-148 ng/g) > ∑12OCPs (1.9-25 ng/g) for dust, and DBDPE (4.9-9647 ng/g) > ∑10PBDEs (90.3-7548 ng/g) > ∑32PCBs (6.1-5025 ng/g) > ∑12OCPs (1.9-250 ng/g) > ∑2DP (2.1-142 ng/g) for soil. PBDEs were the major contributors to POP pollution at e-waste dismantling sites, while PCBs were the most significant contributors at e-waste dumpsites. DBDPE was found to be significantly associated with pollution at both e-waste dismantling and dumpsites. Estimated daily intake (EDI) via dust and soil ingestion and dermal adsorption routes ranged from 1.3 to 2.8 ng/kg bw/day and 0.2-2.9 ng/kg bw/day, respectively. In the worst-case scenario, EDI ranged from 2.9 to 10 ng/kg bw/day and 0.8-5.8 ng/kg bw/day for dust and soil, respectively. The obtained intake levels posed no non-carcinogenic risk, but could increase the incidence of cancer at some of the studied e-waste sites, with values exceeding the USEPA cancer risk lower limit (1.0 × 10-6). Overall, our results suggest that e-waste sites act as emission point sources of POPs.

Effect of typhoons on spatiotemporal patterns of multi-group persistent organic pollutants in sediment of Chinese southeastern coastal estuaries

Estuaries are susceptible to both anthropogenic disturbances and global climate changes. Impacts may be discriminated by pollution patterns of widely quantified persistent organic pollutants (POPs), though data are scarce for extreme climate events. This study quantified four groups of POPs, i.e., polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), and hexachlorocyclohexanes (HCHs), in sediments from seven Chinese coastal estuaries across a gradient of socioeconomic development in their watersheds with comparisons among the pre-typhoon, typhoon, and post-typhoon periods during 2016-2019. The maximal average concentrations, up to 1561 μg PAHs kg-1, 235 μg DDTs kg-1, and 38.9 μg HCHs kg-1, were quantified in the Jiulong River estuary and 7.61 μg PCBs kg-1 in the Jiao River estuary. Anthropogenic activities contributed to the distinctive spatial distributions of four groups of POPs in estuaries with non-agricultural gross domestic product (NAGDP) per capita significantly relating to sedimentary concentrations of PAHs and PCBs and agricultural gross domestic product (AGDP) per capita relating to DDTs and HCHs. Seasonality and typhoons led to less temporal variations in sedimentary POPs concentrations, whose spatial heterogeneity was remarkably reduced in the post-typhoon period rather than in the pre-typhoon and typhoon periods. The results of this study suggested that fingerprinting legacy POPs in spatial and temporal distributions contributed to identifying the effects of anthropogenic disturbances and climate changes on estuarine sediment quality.

Multi-agent collaborative model of e-waste recycling

E-waste production is exploding as a result of rising demand for electronics and a faster rate of replacement. A crucial, yet unresolved issue is how to encourage cooperation among primary agents in the recycling of e-waste. To examine a multi-agent collaborative model of e-waste recycling among local governments, producers, and consumers, this research employs the techniques of evolutionary games and system dynamics. Evolutionary games are used to analyze the strategy choice results, while system dynamics are adopted to depict the decision-making processes. Overall, we find that rewards and penalties affect the stability and efficiency of the collaborative model of e-waste recycling and that the greater the correlation between the rewards-and-penalties mechanism and the strategies, the more stable the model is. Specifically, the results show that: (1) static rewards-and-penalties mechanism is likely to breed mutants and thus is not conducive to stable cooperation; (2) dynamic rewards-and-penalties mechanism can inhibit the instability of e-waste recycling model, but only 60% of producers are willing to build an e-waste recycling system; (3) dynamic rewards-and-penalties optimizing mechanism can ensure that producers and consumers wholeheartedly work for e-waste recycling consistently without local governments regulation; (4) according to the sensitivity analysis, increasing the amount of rewards and penalties can facilitate faster evolution of collaboration in the e-waste recycling system. Finally, this study makes implications for promoting efficiency and stability in e-waste recycling among local governments, producers, and consumers.

Adverse outcome pathways of PBDEs inducing male reproductive toxicity

Polybrominated diphenyl ethers (PBDEs) are widely used brominated flame retardants, they are easily released into environment and causing adverse effects to the ecosystem and human health. This review aims to summarize the research status of PBDEs-induced male reproductive toxicity and its mechanisms at various levels such as molecular/cellular, tissue/organ and individual/population. The Adverse Outcome Pathways (AOPs) diagram showed that PBDEs-induced reactive oxygen species (ROS) production, disruptions of estrogen receptor-α (ERα) and antagonism of androgen receptor (AR) were defined as critical molecular initiating events (MIEs). They caused key events (KEs) at the molecular and cellular levels, including oxidative stress, increased DNA damage, damaging mitochondria, increased glycolipid levels and apoptosis, depletion of ectoplasmic specialization and decreased Leydig cells numbers. These in turn lead to followed KEs at the tissue or organ levels, such as the impaired spermatogenesis, impaired blood-testis barrier and reduced testosterone synthesis and function. As a result, reproductive system-related adverse outcomes (AOs) were reported, such as the decreased sperm quantity or quality, shorten male anogenital distance and cryptorchidism in individual and reduced reproduction of the population. This review assembled information on the mechanisms of male reproductive toxicity induced by PBDEs, and constructed a causal mechanism relationship diagram from different levels using the an AOP framework to provide theoretical basis for ecological risk assessment and environmental management of PBDEs. The AOP framework makes it possible to develop risk management strategies based on toxicity mechanisms and support for development of Integrated Approach to Testing and Assessment (IATA) which are available for regulatory purposes.

Municipal solid waste management with recyclable potential in developing countries: Current scenario and future perspectives

Municipal solid waste (MSW) is a complex challenge to be solved worldwide, intensified in developing countries since in addition to economic and environmental aspects there is also the social aspect represented by the collector individual. From an integrative bibliographic review this study longitudinally analyses the socio-productive inclusion of collectors in the municipal solid waste management (MSWM) at an international level. Aiming: (a) to identify relevant articles describing/studies on MSWM with social inclusion of scavengers around the world; (b) to analyse these articles in order to present its main characteristics; (c) to describe municipal solid waste management with recyclable potential (MSWRP) with socio-productive inclusion of collectors; (d) the study provides a more detailed summary of MSWRP management in some developing countries: Brazil, China, India, Indonesia, Mexico, Nigeria and Pakistan; and (e) to provide a framework indicating the future practices and perspectives of MSWRP. As result, this study presents the paradigms and future questions for an effective improvement of WSWM, such as: Professional Training of Scavengers, Cultural Issues, Empowerment of Scavenger, Recycling Cooperatives and Cooperativism, Policy Issues and Recycling Chain, Management Systems and Process Improvement, Quality of Services Provided, Circular Economy and Informal Sector, Health Quality and Safety at Work, Barriers and Solutions for the Inclusion of the Informal Sector, Environmental, Economic and Social Benefits.

Optimal emission reductions pathway for polybrominated diphenyl ethers in typical household e-waste dismantling products

Waste printed circuit boards (WPCBs) and waste epoxy resin powder (WERP) generated after crushing are the most crucial hazardous materials in the recycling process of household e-waste. In this study, a sustainable treatment approach was established in response to the drawbacks of traditional treatment methods. The baseline and hypothetical scenarios were as follows: (1) scenario 1 (S1): WPCBs mechanical treatment, WERP safe landfill; (2) scenario 2 (S2): WPCBs mechanical treatment, WERP imitation stone bricks production. Based on the material flow analysis and comprehensive evaluation, the most profitable and environmentally friendly scenario was selected and assumed to be promoted in Jiangsu area and China from 2013 to 2029. The analysis result showed that S2 had the best economic performance and polybrominated diphenyl ethers (PBDEs) emission reductions potential. S2 is the best option that can gradually replace the traditional recycling model. With the promotion of S2, China would reduce the emissions of PBDEs by 700.8 kg. Meanwhile, it could save $542.2 million in WERP landfill costs, produce 1260.2 kt of imitation stone bricks, and generate $2308.5 million in economic benefits. In conclusion, this study can offer a new idea for dismantling products treatment of household e-waste and provide scientific knowledge to improve the sustainable management.

Construction of Models To Predict the Effectiveness of E-Waste Control through Capture of Volatile Organic Compounds and Metals/Metalloids Exposure Fingerprints: A Six-Year Longitudinal Study

The significant health implications of e-waste toxicants have triggered the global tightening of regulation on informal e-waste recycling sites (ER) but with disparate governance that requires effective monitoring. Taking advantage of the opportunity to implement e-waste control in the Guiyu ER since 2015, we investigated the temporal variations in levels of oxidative DNA damage, 25 volatile organic compound metabolites (VOCs), and 16 metals/metalloids (MeTs) in urine in 918 children between 2016 and 2021 to demonstrate the effectiveness of e-waste control in reducing population exposure risks. The hazard quotients of most MeTs and levels of 8-hydroxy-2'-deoxyguanosine in children decreased significantly during this time, indicating that e-waste control effectively reduces the noncarcinogenic risks of MeT exposure and levels of oxidative DNA damage. Using mVOC-derived indexes as a feature, a bagging-support vector machine algorithm-based machine learning model was constructed to predict the extent of e-waste pollution (EWP). The model exhibited excellent performance with accuracies >97.0% in differentiating between slight and severe EWP. Five simple functions established using mVOC-derived indexes also had high accuracy in predicting the presence of EWP. These models and functions provide a novel human exposure monitoring-based approach for assessing e-waste governance or the presence of EWP in other ERs.

Blood lead levels of children exposed to e-waste: a systematic review and meta-analysis

Blood lead levels (BLLs) have been decreasing worldwide for decades. However, systematic reviews and quantitative syntheses of BLLs in electronic waste (e-waste)-exposed children are lacking. To summarize temporal trend of BLLs among children in e-waste-recycling areas. Fifty-one studies met the inclusion criteria and included participants from six countries. Meta-analysis was performed using the random-effects model. Results showed that among e-waste-exposed children, the total geometric mean (GM) BLL was 7.54 μg/dL (95% CI: 6.77, 8.31). Children's BLLs displayed a decreasing temporal trend, from 11.77 μg/dL in phase I (2004-2006) to 4.63 μg/dL in phase V (2016-2018). Almost 95% of eligible studies found that children exposed to e-waste had significantly higher BLLs than reference groups. The difference of children's BLLs between the exposure group and the reference group was from 6.60 μg/dL (95% CI: 6.14, 7.05) in 2004 to 1.99 μg/dL (95% CI: 1.61, 2.36) in 2018. For subgroup analyses, except for Dhaka and Montevideo, the BLLs of children from Guiyu in the same survey year were higher than those of children from other regions. Our findings indicate that the gap between BLLs of children exposed to e-waste and those of reference group children is closing, and we appeal that the critical value for blood lead poisoning in children should be lowered in key e-waste-dismantling areas of developing countries, such as Guiyu.

Exploring industrial agglomeration and green finance impact on regional environmental pollution in China based on system-GMM model

The boom of building various industrial agglomerations in China has continued for many years. The relationship between industrial agglomeration and environmental pollution is the core issue of this paper. At the same time, green finance is a new financial development model that takes environmental protection as the core, and effectively promotes the sustainable development of the environment, the economy, and society while maintaining its own sustainable development, so green finance is a major direction for future financial development. This paper selects the data of 30 Chinese provinces from 2004 to 2020 as the research object and uses a system-GMM method to verify the relationship between industrial agglomerations, green finance on regional environmental pollution. It provides theoretical reference for improving global climate change and reduces environmental pollution (EP), concludes as follows. (1) Industrial agglomeration can exacerbate EP level in China, and also exacerbates EP in the western region, but the effect of industrial agglomeration on EP in the eastern and central regions has been insignificant. (2) Green finance can improve environmental pollution. The intensity of EP in economically less developed regions is more sensitive to green finance policies. (3) The correlation effect of industrial agglomeration and green finance can improve environmental pollution, i.e., green finance has an important role in improving EP. However, there are significant differences in different regions. The interaction term between industrial agglomeration and green finance with a non-significant positive coefficient in the eastern region, and it is non-significant negative coefficient in the central region, and a significant negative coefficient in the western region. The work has important theoretical value for achieving the goal of regional sustainable development and green transformation.

Concepts of circular economy for sustainable management of electronic wastes: challenges and management options

The electronic and electrical industrial sector is exponentially growing throughout the globe, and sometimes, these wastes are being disposed of and discarded with a faster rate in comparison to the past era due to technology advancements. As the application of electronic devices is increasing due to the digitalization of the world (IT sector, medical, domestic, etc.), a heap of discarded e-waste is also being generated. Per-capita e-waste generation is very high in developed countries as compared to developing countries. Expansion of the global population and advancement of technologies are mainly responsible to increase the e-waste volume in our surroundings. E-waste is responsible for environmental threats as it may contain dangerous and toxic substances like metals which may have harmful effects on the biodiversity and environment. Furthermore, the life span and types of e-waste determine their harmful effects on nature, and unscientific practices of their disposal may elevate the level of threats as observed in most developing countries like India, Nigeria, Pakistan, and China. In the present review paper, many possible approaches have been discussed for effective e-waste management, such as recycling, recovery of precious metals, adopting the concepts of circular economy, formulating relevant policies, and use of advance computational techniques. On the other hand, it may also provide potential secondary resources valuable/critical materials whose primary sources are at significant supply risk. Furthermore, the use of machine learning approaches can also be useful in the monitoring and treatment/processing of e-wastes. HIGHLIGHTS: In 2019, ~ 53.6 million tons of e-wastes generated worldwide. Discarded e-wastes may be hazardous in nature due to presence of heavy metal compositions. Precious metals like gold, silver, and copper can also be procured from e-wastes. Advance tools like artificial intelligence/machine learning can be useful in the management of e-wastes.

Co-exposure levels of volatile organic compounds and metals/metalloids in children: Implications for E-waste recycling activity prediction

Identifying informal e-waste recycling activity is crucial for preventing health hazards caused by e-waste pollution. This study attempted to build a prediction model for e-waste recycling activity based on the differential exposure biomarkers of the populations between the e-waste recycling area (ER) and non-ER. This study recruited children in ER and non-ER and conducted a quasi-experiment among the adult investigators to screen differential exposure or effect biomarkers by measuring urinary 25 volatile organic compound (VOC) metabolites, 18 metals/metalloids, and 8-hydroxy-2'-deoxyguanosine (8-OHdG). Compared with children of the non-ER, the ER children had higher metal/metalloid (e.g., manganese [Mn], lead [Pb], antimony [Sb], tin [Sn], and copper [Cu]) and VOC exposure (e.g., carbon-disulfide, acrolein, and 1-bromopropane) levels, oxidative DNA damage, and non-carcinogenic risks. Individually added 8-OHdG, VOC metabolites, and metals/metalloids to the support vector machine (SVM) classifier could obtain similar classification effects, with the area under curve (AUC) ranging from 0.741 to 0.819. The combined inclusion of 8-OHdG and differential VOC metabolites, metals/metalloids, and mixed indexes (e.g., product items or ratios of different metals/metalloids) in the SVM classifier showed the highest performance in predicting e-waste recycling activity, with an AUC of 0.914 and prediction accuracy of 83.3 %. "Sb × Mn", followed by "Sn × Pb/Cu", "Sb × Mn/Cu", and "Sn × Pb", were the top four important features in the models. Compared with non-ER children, the levels of urinary Mn, Pb, Sb, Sn, and Cu in ER children were 1.2 to 2.4 times higher, while the levels of "Sb × Mn", "Sn × Pb/Cu", "Sb × Mn/Cu", and "Sn × Pb" were 3.5 to 4.7 times higher, suggesting that these mixed indexes could amplify the differences between e-waste exposed and non-e-waste exposed populations. With the continued inclusion of new biomarkers of e-waste pollution in the future, our prediction model is promising for screening informal e-waste recycling sites.

A lifelong journey of lead in soil profiles at an abandoned e-waste recycling site: Past, present, and future

Heavy metal pollutants resulting from human activities consistently move from the topsoil to the subsoil profiles under the influence of rainfall leaching. This study intends to predict the long-term transport of heavy metals at an abandoned e-waste recycling site with respect to historical pollution activities, land use, and metal pollutant dynamics. Our results showed that the site was seriously contaminated with heavy metals (Cd, Cu, Pb, and Zn) in the soil profiles. More specifically, Cu and Zn accumulated primarily in the upper layers of the soil profile owing to their weak mobility, while significant migration of Cd and Pb was observed in the deeper soil layers. Furthermore, to clarify the fate of Pb in soil profiles, Pb isotopes and the Hydrus model were used to trace the sources of Pb contamination and predict its long-term distribution. The Pb isotope results suggest that past e-waste recycling activities significantly contributed to the heavy metal concentration in the soil profiles; however, other anthropogenic sources such as vehicle exhaust had smaller impacts. Moreover, our model findings predicted that within the next 30 years, 60% of Pb contaminants will be concentrated in the surface soil. Together these results provide a theoretical foundation and scientific basis for evaluating, controlling, and remediating abandoned e-waste recycling sites.

Congener-specificity, dioxygenation dependency and association with enzyme binding for biodegradation of polybrominated diphenyl ethers by typical aerobic bacteria: Experimental and theoretical studies

Polybrominated diphenyl ethers (PBDEs) are a group of organic pollutants that have attracted much concerns of scientific community over the ubiquitous distribution, chemical persistence and toxicological risks in the environment. Though a great number of aerobic bacteria have been isolated for the rapid removal of PBDEs, the knowledge about biodegradation characteristics and mechanism is less provided yet. Herein, the congener-specificity of aerobic biodegradation of PBDEs by typical bacteria, i.e. B. xenovorans LB400 was identified with the different biodegradation kinetics, of which the changes were largely hinged on the bromination pattern. The more bromination isomerically at ortho-sites other than meta-sites or the single bromination at one of aromatic rings might always exert the positive effect. The biodegradation of PBDEs should be thermodynamically constrained to some extent because the calculated Gibbs free energy changes of initial dioxygenation by quantum chemical method increased with the increase of bromination. Within the transition state theory, the high correlativity between the apparent biodegradation rates and Gibbs free energy changes implied the predominance and rate-limiting character of initial dioxygenation, while the regioselectivity of dioxygenation at the ortho/meta-sites was also manifested for the more negative charge population. The molecular binding with the active domain of dioxygenase BphA1 in aerobe was firstly investigated using docking approach. As significantly illustrated with the positive relationship, the higher binding affinity with BphA1 should probably signify the more rapid biodegradation. Besides the edge-on π-π stacking of PBDEs with F227 or Y277 and π-cation formulation with histidines (H233, H239) in BphA1, the reticular hydrophobic contacts appeared as the major force to underpin the high binding affinity and rapid biodegradation of PBDEs. Overall, the experimental and theoretical results would not only help understand the aerobic biodegradation mechanism, but facilitate enhancing applicability or strategy development of engineering bacteria for bioremediation of PBDEs in the environment.

E-waste management, treatment options and the impact of heavy metal extraction from e-waste on human health: Scenario in Vietnam and other countries

Ho Chi Minh (HCM) City is the most important urban region of Vietnam, Southeast Asia. In recent times, the quantity of electronic waste (e-waste) has been growing by several thousand tonnes every year. In this research, some of the existing and developing technologies being employed for the recycling of e-waste have been reviewed. Accordingly, the paper has been divided into three sections namely, e-waste treatment technologies in Ho Chi Minh City, the effect of heavy metals on human health and the extraction of metals from e-waste using pyrolysis, hydrometallurgy, bioleaching, mechanical, and air classifier methods, respectively. The extraction of precious metals and heavy metals such as Cd, Cr, Pb, Hg, Cu, Se, and Zn from e-waste can be hazardous to human health. For example, lead causes hazards to the central and peripheral nervous systems, blood system and kidneys; copper causes liver damage; chronic exposure to cadmium ends up causing lung cancer and kidney damage, and mercury can cause brain damage. Thus, this study examines the key findings of many research and review articles published in the field of e-waste management and the health impacts of metal pollution.

Global research into the relationship between electronic waste and health over the last 10 years: A scientometric analysis

Introduction

The aims of this research were to conduct the first holistic and deep scientometric analysis of electronic waste and health and provide with the prediction of research trends and hot topics.

Method

A comprehensive literature search was conducted via the Web of Science Core collection databases on 26 August 2022 to identify all articles related to electronic waste and health. A total of 652 records have been extracted from the Web of Science after applying inclusion and exclusion criteria and were analyzed using bibliometrix software of R-package, VOSviewer, and CiteSpace, visualized by tables and diagrams.

Result

The number of publications and total citations had shown a general growth trend from 2012 to 2021, with an average annual growth rate of 23.74%. Mainland China was the significant nation with the greatest number of publications, citations, and international links. The journal publishing the most was "Science of the Total Environment" (n = 56). Huo X and Hu XJ were the top two author contributing to this field with the highest h-index (23). Over time, the focus in this field shifted to exposure to heavy metal, polychlorinated biphenyls, polybrominated biphenyl ethers, and poly- and perfluorinated alkyl substances from electronic waste, and managements, such as hydrometallurgy.

Discussion

By this scientometric analysis, we found that the most active country, journal, organization and author contributing to this filed, as well as high impact documents and references and research hotspots. Also, we found that the hotspots might be exposure to toxic substances from electronic waste procession, its impact on human health and relevant managements. And evironmentally friendly materials to replace heavy metal mate rials, and environmentally friendly and effective recycling methods of electronic waste need to be further studied.

Evaluating postnatal exposure to six heavy metals in a Chinese e-waste recycling area

This study is the first to assess postnatal exposure to heavy metals using breast milk in an electronic waste (e-waste) recycling area. From January to April 2021, 102 and 97 breastfeeding women were recruited from an e-waste recycling area and a control area, respectively. Four weeks after delivery, medical staff collected 20 mL of breast milk from each participant. The breast milk was tested for six heavy metals (lead, cadmium, chromium, arsenic, copper, and manganese) using inductively coupled plasma mass spectrometry (ICP-MS). The estimated daily intake (EDI) of infants during breastfeeding was calculated to assess the impact of postnatal exposure to heavy metals on infant health. The concentrations of chromium and lead in the breast milk were significantly higher in the e-waste recycling area than in the control area. Chromium concentrations in breast milk was 34.3%, exceeding the permissible limits set by the World Health Organization (WHO), in the e-waste recycling area, which is 16 times higher than that in the control areas. The EDIs of lead and chromium in the e-waste area were twice as those in the control area. This strongly indicates that the potential impact of postnatal exposure to lead and chromium on infant and child health in e-waste recycling areas cannot be ignored. Infants and children in e-waste recycling areas are at risk of long-term exposure to heavy metals. Therefore, ongoing health monitoring is necessary.

Four-year population exposure study: Implications for the effectiveness of e-waste control and biomarkers of e-waste pollution

E-waste pollution has emerged as a significant environmental concern. To assess the impact of e-waste control on human pollutant exposure risk and identify appropriate biomarkers to classify e-waste pollution levels, we performed longitudinal population exposure monitoring research in an e-waste recycling area in China after e-waste control. The urinary levels of oxidative stress markers and typical pollutants emitted during e-waste recycling, including heavy metals, polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs), were continuously monitored in the surrounding population (including 275 children and 485 adults) from 2016 to 2019 using high-performance liquid chromatography-tandem mass spectrometry and inductively coupled plasma-mass spectrometry. The results showed that exposure to PAHs, VOCs and heavy metals was significantly associated with oxidative stress levels in urine. After e-waste control, the exposure levels of most PAHs and VOCs and a few heavy metals in the population significantly decreased. Interestingly, the level of 8-hydroxy-2'-deoxyguanosine (a biomarker of oxidative DNA damage) in children significantly decreased by 17.6 %, from 9.45 μg/g CRE in 2017 to 7.79 μg/g CRE in 2019 (p < 0.01). Thus, implementing e-waste control measures effectively reduced the human exposure risk to e-waste pollutants. Urinary tin (Sn), s-phenylmercapturic acid (PMA), 2-&3-hydroxyfluorene (2-&3-OHF), 3-hydroxyphenanthrene (3-OHPhe), and 1-hydroxypyrene (1-OHP) levels decreased significantly and monotonically over time (p < 0.01). The levels of urinary Sn and PMA in combination with 1-OHP, 2-&3-OHF, or 3-OHPhe as biomarkers demonstrated an excellent ability to classify e-waste pollution. These biomarkers will facilitate evaluations of the effectiveness of the governmental pollution regulations and policy measures. Additionally, children were generally exposed to higher levels of heavy metals and VOCs and suffered higher levels of oxidative stress damage than adults, suggesting that children are more vulnerable to e-waste pollution. This work will provide a reference for e-waste management and control.

Urgency of technology and equipment upgrades in e-waste dismantling base: Pollution identification and emission reduction

Recycling of electronic waste (e-waste) and inevitable pollution under current technology have always been a concern of people. Generation and release of pollutants in the recycling process of e-waste are closely related to processing technology and equipment. In this paper, the pollution characteristics of different functional areas and critical processing units in formal e-waste dismantling base have been studied systematically and comprehensively. The results showed that the overall pollutants concentration in crushing workshop and cathode ray tube (CRT) monitor disposing workshop are much higher than other functional areas. Screen-cone glass separation for CRT monitor was the processing unit with the greatest exposure risk and the hazard index (HI) of Pb was 4.60. Pollutant emission factor of the main processing units was calculated and the waste printed circuit board (WPCB) crushing was the most polluted unit. Appropriate improvements in technology and equipment can effectively reduce the generation and release of pollutants. Some reasonable prospects about intelligent equipment and special technologies were proposed for e-waste disposal. All the results provided theoretical and data support for pollution control and technology upgrade of the formal e-waste dismantling base.

Preparation of hydrothermally solidified materials from waste cathode ray tube panel glass for construction applications

Solidification of cathode ray tube (CRT) panel glass was carried out using a hydrothermal processing method. In this way, the glass powder was first compacted in a mold at 20 MPa, and then hydrothermally cured in an autoclave under saturated steam pressure at 200 ℃ for 6 h. The CRT panel glass was then hydrothermally solidified by the formation of tobermorite (Ca₅Si₆O₁₆(OH)₂·4H₂O), which was encouraged by the addition of slaked lime (Ca(OH)₂). The strength of solidified specimen heavily depended on the amount of tobermorite formed, with higher concentrations of tobermorite producing commensurately greater mechanical strength. With the addition of Ca(OH)₂ at 20-30% by mass, the specimen achieved a bending strength of approximately 16 MPa, which was sufficiently great for using as a construction material. As such, there is cause to believe that the hydrothermal processing method used here may have great potential for resource utilization of CRT panel glass, and the performance of the product is suitable for use as building materials.

Toxic effects of polystyrene nanoplastics and polybrominated diphenyl ethers to zebrafish (Danio rerio)

Nanoplastics (NPs) are good carriers of persistent organic pollutants (POPs) such as polybrominated diphenyl ethers (PBDEs), and can alter their bioavailability and toxic impacts to aquatic organisms. This study highlights the single and combined toxic effects of polystyrene nanoplastics (PS-NPs) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47, one of the dominant congeners of PBDEs) on zebrafish embryos after an exposure duration of up to 120 hpf. Results showed that PS-NPs and BDE-47 co-exposure exacerbated the morphological deformities in terms of pericardial edema, yolk sac edema and curved tail in zebrafish larvae. Compared to BDE-47 single exposure, the combined exposure caused lower survival rates, shorter body lengths, and accelerated spontaneous movements. Further, PS-NPs were quickly aggregated on the surface of the embryonic chorions covered almost the entire membrane at 12 and 48 hpf, and concentration dependent accumulation was also found in the brain, mouth, trunk, gills, heart, liver and gastrointestinal tract at the larval stages. During the recovery period (7 days), PS-NPs were released from all the organs, with the highest elimination from the gastrointestinal tract. Histopathological examination revealed that co-exposure caused greater damage to retinal structures, muscle fibers and cartilage tissues. Responses of hypothalamic-pituitary-thyroid axis (CRH, TSHβ, NIS, TTR, Dio2, TG, TRα and TRβ) and reproduction (Esr2 and Vtg1) related genes were also investigated, and results showed that the co-exposure induced more significant upregulated expressions of TSHβ, TG, Doi 2, and TRβ, compared to BDE-47 single exposure. In conclusion, co-exposure to NPs and BDE-47 exacerbated developmental and thyroid toxicity in zebrafish, generally elucidating the toxicological effects mediated by complex chemical interactions between NPs with POPs in the freshwater environment.

Characteristics of unorganized emissions of microplastics from road fugitive dust in urban mining bases

Nowadays, plastic pollution attracts attention, while data on microplastic (MP) emissions to atmosphere from urban mining bases are rarely quantified. In this paper, the emission characteristics of MPs in road fugitive dust from two urban mining bases were studied, the emission factors of MPs from road fugitive dust source were updated, and emission inventories were established. It is estimated that the waste glass recycling base and the e-waste dismantling plant emit 1265.53 g and 40.5 g of MPs into atmosphere respectively each year, with the highest percentage of tire micro-rubber. The roads with the most emissions are located in the middle of warehouses and workshops. Emission factors for MPs mainly depend on average vehicle weight, and heavy vehicles cause more MP emissions. Uncertainty analysis of the inventory indicated that the random error of MP emissions on a single road in waste glass recycling base was -79.1%-187.1%, while in e-waste dismantling plant was -62.7%-102.05%, which is mainly related to the silt loading. This study completes the quantitative data on the unorganized emissions of MPs from road fugitive dust in these two typical urban mining bases, and provides guidance for air pollution prevention and control.

Relationship between dioxins and steroid hormone in 6-year-olds: A follow-up study in an e-waste region of China

We conducted a follow-up observational study on the effects of dioxin exposure on the synthesis of steroid hormones in infants during the perinatal period. The participants included 42 pairs of mothers and infants that were previously studied in 2015. We analyzed four types of steroid hormones including progesterone, testosterone, androstenedione (A-dione), and dehydroepiandrosterone (DHEA) in the serum samples of 6-year-olds and the concentration of dioxins in breast milk. A multivariate linear regression was performed to associate steroid hormones (dependent variables) and dioxins with the body mass index (BMI), sex, age, and residence of participants (independent variables). The results were reported as β (standardized coefficient) and p-values. We found that dioxins have a significant negative correlation with DHEA and A-dione but no significant relationship with progesterone and testosterone. However, in previous studies, we found that testosterone and progesterone levels were significantly related to dioxins in 4-year-olds. We concluded that dioxins can affect the level of steroid hormones, but their effects fluctuate, and the harm caused by dioxins in children requires further long-term monitoring.

Analysis of environmental sustainability of e-waste in developing countries - a case study from Pakistan

The electronic waste generation rate is increasing drastically at a rate of 3 to 5% per year in developing countries. The aim of this study is to analyze the environmental sustainability and economic benefits of such e-waste management in the developing economies like Pakistan. The life cycle assessment (LCA) method has been employed for streamlined impact analysis of the end-of-life processing of e-waste focusing mainly on laptop computers and liquid crystal display (LCD) desktop computers in Pakistan. The method of cumulative exergy extraction from the natural environment (CEENE) has also been deployed for the relative assessment of resources' consumption of e-waste recycling versus landfilling scenario. The determined impact scores are 1.79E + 03 kg CO₂ eq., 7.19E-07 kg CFC-11 eq., 1.02E + 03 kg 1,4-DCB, 7.13E + 01 kg 1,4-DCB, and 3.41E-03 kg Cu eq. in climate change potential, stratospheric ozone depletion, ecotoxicity potential, human noncarcinogenic potential, and mineral resource depletion impact categories, respectively. The results of CEENE analysis reveal that approximately 80% of the impact on natural resources is reduced by the efficient recycling of e-waste. The comparative assessment of respective scores for current and target material weight recovery (MWR) indicators represented that by increasing the MWR indicator by 33.8% for laptop computers and by 27.2% for LCD computers, the country will achieve an annual economic benefit of US $191.56 million. This is greatly significant for a transitional shift towards e-waste revalorization while realizing the objectives of sustainable resource consumption. Innovative improvement measures ensuring economically feasible, energy-efficient, and environment friendly waste collection, treatment, and recycling practices present an invaluable opportunity for developing countries.

Consumer behaviour towards storage, disposal and recycling of e-waste: systematic review and future research prospects

Purpose

With the rapid increase in the consumption of electrical and electronic innovations, responsible management and recycling of electronic waste (e-waste) or waste electrical and electronic equipment (WEEE) has been a significant concern for the governments, stakeholders, researchers and industry practitioners around the world. Consumer awareness, disposal behaviour and perception are chief facets of designing sustainable management strategies. Although researchers have widely studied e-waste over many years, the research focusing on consumer awareness about e-waste recycling has gained momentum recently. This paper aims to systematise the existing literature and explore future research prospects on household e-waste sorting behaviour.

Design/methodology/approach

Web of science (WoS) core collection was searched using selected keywords to identify relevant articles published from 2001 to 2021. The search resulted in 1,156 research articles published from 2001 to 2021. After a detailed study, 85 articles were shortlisted for in-depth review. The review was conducted based on global trends, top journals, most prolific authors, most active e-waste research countries, and institutions centring on consumer participation in e-waste disposal and recycling behaviour. The present research has also identified around eleven factors that seem to have a bearing on consumer behaviour towards storage, disposal and recycling of e-waste.

Findings

E-waste research has gained increased attention in the last five years. The majority of the studies has focused on motivational factors and ignore the risks associated with handling e-waste. The present study reports the pertinent issue of lack of awareness among the masses about e-waste handling and disposal. Thus, bringing to the fore the lack of awareness programmes and initiatives. The analysis presents the gaps in the literature and future research agendas.

Originality/value

The review article will help in providing an in-depth understanding of consumer behaviour towards storage, disposal and recycling of e-waste and delineates the future direction of research that may be undertaken in this field of study.

Legacy organochlorines in estuarine sediment in relation to socioeconomic pattern in multi-coastal watersheds

Estuarine sediment quality is highly associated with anthropogenic activities in watersheds. This study attempts to couple socioeconomic patterns with estuarine sediment quality via legacy organochlorines in 14 Chinese coastal watersheds. Sedimentary concentrations of HCHs, DDTs, and PCBs showed a significant spatiality in estuary, up to 48.7 ± 15.1, 89.0 ± 46.4, and 54.5 ± 17.2 ng g-1, which were predominated by β-HCH, p,p'-DTs, and tri- to penta-PCBs, respectively. Ecological risk of organochlorines was negligible except few moderate risks for DDTs and PCBs against the first class quality of the marine sediment quality guidelines of China. Sedimentary DDT and PCB concentrations were significantly delineated by an environmental Kuznets curve model as a function of non-agricultural GDP per capita in watersheds, while HCHs by an increasing linear model. Findings of this study provide a tool to quantify the contribution of anthropogenic development in watershed to environmental change in estuary across the world.

Urinary heavy metals in residents from a typical city in South China: human exposure and health risks

Although heavy metal pollution has developed into a major global environmental problem, most research has focused on specific elements, especially arsenic (As) and selenium (Se), and on the health risks to people in polluted areas or by occupation. This study investigated the urine of 480 participants from Guangzhou with a population of 18 million and targeted nine heavy metals: As, Se, chromium (Cr), manganese (Mn), nickel (Ni), cadmium (Cd), lead (Pb), antimony (Sb), and mercury (Hg). The heavy metals were widely detected, of which As, Se, Cd, and Pb all exceed 98%. Among the toxicants, As showed the highest concentration, followed by Se with 40.5 and 35.4 μg/L, respectively. The heavy metal levels from suburban subjects were generally higher than those in urban subjects (except for Sb), and the Cd level of males was lower than that of females. Concentrations were related to age, body mass index, alcohol consumption, and smoking. According to the health risk assessment, most subjects experienced potential non-carcinogenic risk from As, Cd, Se, and Hg, which accounted for 38.2%, 8.83%, 8.31%, and 3.38%, respectively. The carcinogenic risk of As and Cd surpassed the risk level of 10^-6, and 90.1% and 35.4% of the subjects, respectively, exceeded 10^-4, an unacceptable risk level. More attention to the high carcinogenic risk from heavy metals and the high detected levels of As and Cd is required.

Formal waste treatment facilities as a source of halogenated flame retardants and organophosphate esters to the environment: A critical review with particular focus on outdoor air and soil

Extensive use of halogenated flame retardants (HFRs) and organophosphate esters (OPEs) has generated great concern about their adverse effects on environmental and ecological safety and human health. As well as emissions during use of products containing such chemicals, there are mounting concerns over emissions when such products reach the waste stream. Here, we review the available data on contamination with HFRs and OPEs arising from formal waste treatment facilities (including but not limited to e-waste recycling, landfill, and incinerators). Evidence of the transfer of HFRs and OPEs from products to the environment shows that it occurs via mechanisms such as: volatilisation, abrasion, and leaching. Higher contaminant vapour pressure, increased temperature, and elevated concentrations of HFRs and OPEs in products contribute greatly to their emissions to air, with highest emission rates usually observed in the early stages of test chamber experiments. Abrasion of particles and fibres from products is ubiquitous and likely to contribute to elevated FR concentrations in soil. Leaching to aqueous media of brominated FRs (BFRs) is likely to be a second-order process, with elevated dissolved humic matter and temperature of leaching fluids likely to facilitate such emissions. However, leaching characteristics of OPEs are less well-understood and require further investigation. Data on the occurrence of HFRs and OPEs in outdoor air and soil in the vicinity of formal e-waste treatment facilities suggests such facilities exert a considerable impact. Waste dumpsites and landfills constitute a potential source of HFRs and OPEs to soil, and improper management of waste disposal might also contribute to HFR contamination in ambient air. Current evidence suggests minimal impact of waste incineration plants on BFR contamination in outdoor air and soil, but further investigation is required to confirm this.

Effect of light combination on the characteristics of dissolved organic matter and chemical forms of Cd in the rhizosphere of Arabidopsis thaliana involved in phytoremediation

Light, one of the most important natural resources for plant species, significantly influences the biomass yield and nutrient uptake capacity in plants. Light sources with different spectra combinations can impact the bioavailability, toxicity, and solubility of heavy metals in soils by altering the concentrations and fractionations of soil dissolved organic matter (DOM). A series of light irradiation treatments were performed to evaluate the influence of red, yellow, and blue lights on the characteristics of DOM in the rhizosphere soils of Arabidopsis thaliana. The results showed that monochromatic red light significantly raised the levels of DOM and proportions of hydrophilic fractionations in the rhizosphere of A. thaliana relative to the control, while monochromatic blue light had the opposite effect. Moreover, the proportions of hydrophobic acid, which can mobilize Cd effectively, also raised with increasing doses of red light, which stimulated Cd mobilization. The application of yellow light not only increased the levels of hydrophobic acid in monochromatic red light treatment but also decreased the proportion of hydrophobic fractions in monochromatic blue light treatment, partially weakening the negative impacts of pure blue light on soil Cd activation. Moreover, DOM from the combined red, yellow, and blue lights resulted in a significantly stronger Cd extraction efficiency than the other light irradiation treatments, consequently enhancing the Cd phytoextraction efficiency of A. thaliana. The findings of this study demonstrated that a suitable light combination could enhance the phytoremediation effect of A. thaliana by activating soil Cd, and this method can be extrapolated to the real field, where light irradiation can be easily applied and modulated.

Environmental contamination and human exposure of polychlorinated biphenyls (PCBs) in China: A review

Polychlorinated biphenyls (PCBs), together with 11 other organic compounds, were initially listed as persistent organic pollutants (POPs) by the Stockholm Convention because of their potential threat to ecosystems and humans. In China, many monitoring studies have been undertaken to reveal the level of PCBs in environment since 2005 due to the introduced stricter environmental regulations. However, there are still significant gaps in understanding the overall spatial and temporal distributions of PCBs in China. This review systematically discusses the occurrence and distribution of PCBs in environmental matrices, organisms, and humans in China. Results showed that PCB contamination in northern and southern China was not significantly different, but the PCB levels in East China were commonly higher than those in West China, which might have been due to the widespread consumption of PCBs and intensive human activities in East China. Serious PCB contamination was found in e-waste disassembling areas (e.g., Taizhou of Zhejiang Province and Qingyuan and Guiyu of Guangdong Province). Higher PCB concentrations were also chronicled in megalopolises and industrial clusters. The unintentionally produced PCBs (UP-PCBs) formed during industrial thermal processes may play an increasingly significant role in PCB pollution in China. Low PCB levels were recorded in rural and underdeveloped districts, particularly in remote and high-altitude localities such as the Tibetan Plateau and the South China Sea. However, these data are limited. Human exposure to PCBs is closely related to the characteristics of environmental pollution. This review also discusses existing issues and future research prospects on PCBs in China. For instance, the accumulation characteristics and migration regularities of PCBs in food webs should be further studied. More investigations should be undertaken to assess the quantitative relationship between external and internal exposure to PCBs. For example, bioaccessibility and bioavailability studies should be supplemented to evaluate human health risks more accurately.

Reverse logistics research of municipal hazardous waste: a literature review

The reverse logistics of municipal hazardous waste (RLMHW) have received close attention from researchers and practitioners alike, given the essential impact of safe transportation and effective management of hazardous waste on public health and environmental sustainability. There are a great number of studies in the extant literature on RLMHW, with many and diverse research topics; however, a concise and complete overview of the research works already conducted in this particular area is conspicuous by its absence. This paper strives to fill the gap through the conduct of rigorous systematic literature review of RLMHW in the past three decades, and then establish a framework of studies on RLMHW. The main contributions of this study are as follows: (1) to identify the trend of journals publishing research papers on RLMHW; (2) to extract the main topics in studies on RLMHW; (3) to locate the most popular research areas of RLMHW; (4) to summarize the methods adopted in studies on RLMHW; (5) to identify research deficiencies in certain categories of RLMHW; and (6) to establish the future research directions of RLMHW. The main implications of the study are to offer a better understanding of RLMHW by systematic crystallization of archival data in a systematic chronological order across central issues. This study contributes to scholarly debate in this field by serving as a snapshot paper to document the development of the field and gives input to policymakers in process design and policy making in the domain of RLMHW.

Health risk assessment and development of human health ambient water quality criteria for PBDEs in China

Polybrominated diphenyl ethers (PBDEs) are not only a class of highly efficient brominated flame retardants (BFRs) but also a class of typical persistent organic pollutants (POPs) that are persistent and widely distributed in various environmental media. This study examined the concentrations of PBDEs in five environmental media (water, soil, air, dust, and food) and two human body media (human milk and blood) in China from 2010 to 2020. In addition, this study conducted multi-pathway exposure health risk assessments of populations of different ages in urban, rural, key regions, and industrial factories using the Monte-Carlo simulation. Finally, the human health ambient water quality criteria (AWQC) of eight PBDEs were derived using Chinese exposure parameters and bioaccumulation factors (BAFs). The results showed that the eastern and southeastern coastal regions of China were heavily polluted by PBDEs, and the variation trends of the ΣPBDEs concentrations in the different exposure media were not consistent. PBDEs did not pose a risk to urban and rural residents in ordinary regions, but the hazard indexes (HIs) for residents in key regions and occupational workers exceeded the safety threshold. Dust exposure was the primary exposure pathway for urban and rural residents in ordinary regions, but for residents in key regions and occupational workers, dietary exposure was the primary exposure pathway. BDE-209 was found to be the most serious individual PBDE congener in China. The following human health AWQC values of the PBDEs were derived: drinking water exposure: 0.233-65.2 μg·L^-1; and drinking water and aquatic products exposure: 8.51 × 10^-4-1.10 μg·L^-1.

Issues and solutions of electronic waste urban mining for circular economy transition: An Indian context

The rapid consumption of advanced e-products has intensified problems for the linear economy; constantly diminishing natural resources employed in production processes have created a need of recycle and reuse. Although the transition to a circular economy proposes to end the loop of e-products, it needs the application of processes such as urban mining to recover resources as secondary raw material. The present study intends to examine the issues and challenges of electronic waste urban mining (EWUM) in India that need to be assessed for the development of a sustainable economy. To accomplish this, the current study employs integrated Multi-Criteria-Decision making methods (MCDM). Step-Wise Weight Assessment Ratio Analysis (SWARA) is used to prioritize issues and their possible solutions with Weighted Assessment Sum Product Assessment (WASPAS) methods introduced to explore these challenges and provide solutions for managing EWUM. There is an immediate need to acknowledge the issues confronted by stakeholders in urban mining processes for successful transition to a circular economy. A better understanding of the issues will help policy makers and decision makers to implement best practices to enhance the urban mining process in India. This study has shown that socio-economic (SE) issues are the most critical issues in EWUM in India. The possible solutions that would have most impact are to enhance awareness campaigns for people to educate themselves regarding e-waste, train staff to handle safe disposal of e-waste and produce eco-friendly electronic products.

Converting spent lithium cobalt oxide battery cathode materials into high-value products via a mechanochemical extraction and thermal reduction route

This study innovatively combines mechanochemistry and high-temperature thermal reduction to achieve the recovery of valuable metals from spent LIBs. First, under the action of mechanical force, the crystal structure of lithium cobalt oxide (LiCoO₂) found in the cathode materials of spent LIBs was destroyed and converted into lithium carbonate (Li₂CO₃) and Li-free residue (C/Co₃O₄) using dry ice as a co-grinding reagent. The optimum Li₂CO₃ recovery conditions were determined to be as follows: a ratio of dry ice: LiCoO₂ powder mass of 20:1; a rotation speed of 700 rpm, and a reaction time of 1.5 h. With these conditions the maximum percentage of Li₂CO₃ recovered was 95.04 wt%. The Co₃O₄ in Li-free residue was reduced to a high-value Co⁰ product via a high-temperature (800 °C) heat treatment. Gibbs free energy analysis confirmed that the carbon in the Li-free residue could be used as a self-reducing reagent for the thermal reduction of Co₃O₄. The reactants and products of each step were characterized by XRD, FT-IR, XPS and SEM techniques. The green route for recycling spent LIBs that this study proposes realizes the green and cost-effective conversion of LiCoO₂ to high-value products, which may become an outstanding example of recycling spent LIBs.

Electronic Waste, an Environmental Problem Exported to Developing Countries: The GOOD, the BAD and the UGLY

Electronic waste (e-waste) is a rapidly developing environmental problem particularly for the most developed countries. There are technological solutions for processing it, but these are costly, and the cheaper option for most developed countries has been to export most of the waste to less developed countries. There are various laws and policies for regulating the processing of e-waste at different governance scales such as the international Basel Convention, the regional Bamoko Convention, and various national laws. However, many of the regulations are not fully implemented and there is substantial financial pressure to maintain the jobs created for processing e-waste. Mexico, Brazil, Ghana Nigeria, India, and China have been selected for a more detailed study of the transboundary movements of e-waste. This includes a systematic review of existing literature, the application of the Driver, Pressure, State, Impact, Response (DPSIR) framework for analysing complex problems associated with social ecological systems, and the application of the Life Cycle Assessment (LCA) for evaluating the environmental impact of electronic devices from their manufacture through to their final disposal. Japan, Italy, Switzerland, and Norway have been selected for the LCA to show how e-waste is diverted to developing countries, as there is not sufficient data available for the assessment from the selected developing countries. GOOD, BAD and UGLY outcomes have been identified from this study: the GOOD is the creation of jobs and the use of e-waste as a source of raw materials; the BAD is the exacerbation of the already poor environmental conditions in developing countries; the UGLY is the negative impact on the health of workers processing e-waste due to a wide range of toxic components in this waste. There are a number of management options that are available to reduce the impact of the BAD and the UGLY, such as adopting the concept of a circular economy, urban mining, reducing loopholes and improving existing policies and regulations, as well as reducing the disparity in income between the top and bottom of the management hierarchy for e-waste disposal. The overarching message is a request for developed countries to help developing countries in the fight against e-waste, rather than exporting their environmental problems to these poorer regions.

E-waste-word of mouth (EW-WOM) generation: a fuzzy set qualitative comparative analysis (fs/QCA)

Purpose

This study aims to examine the asymmetrical relationships among information-sharing desire, moral attitudes, lack of concern, relative advantage, market maven tendency and complexity as the antecedents of E-waste-word of mouth (EW-WOM) generation.

Design/methodology/approach

To obtain a holistic view and the interrelationships between conditions, the configural analysis was conducted to assess the asymmetrical relationships using fuzzy set qualitative comparative analysis (fs/QCA). In addition, construct validity, reliability and symmetrical relationships between antecedent conditions (i.e. exogenous constructs) and outcome conditions (i.e. endogenous constructs) are examined using variance-based structural equation modeling (VB-SEM) technique.

Findings

Results imply that market maven tendency accounts for 86.8% of the sum of the memberships in EW-WOM generation. In total, 11 configurations show sufficiency in constructing EW-WOM generation. The configuration of relativeadvanta*moralattitudes*marketmaventend shows the highest consistency value (0.939684) in producing EW-WOM generation (outcome condition). The ∼relativeadvanta *moralattitudes*complexity*∼lackfconcern with raw coverage of 0.626757 and consistency value of 0.864088 show the most sufficient configuration path in producing the outcome.

Originality/value

Product review and recommendation are easily shared in various communication formats and consumers are prone to disseminate information and their experiences with other market segments. However, the role and phenomena of such viral communication in preventing environmental issues caused by electronic and electrical devices (i.e. E-waste) are not well understood. This study is among a few attempts at understanding consumer's decision-making process to engage in E-waste activities such as the reduction of garbage, recycling, compositing and the reuse of electronic or electrical devices.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/OIR-11-2019-0343

High serum IgG subclass concentrations in children with e-waste Pb and Cd exposure

Immunoglobulin G (IgG) is the predominant component of the humoral immune system. Epidemiological studies have shown that lead (Pb) or cadmium (Cd) exposure is associated with changes in human IgG levels, and alteration of IgG subclass production can be induced by differential modulation of Th1 and Th2 cytokines caused by Pb or Cd exposure. However, no study has focused on the adverse effects of Pb and Cd co-exposure on IgG subclass production by regulating Th1/Th2 cytokines in children living in electronic waste (e-waste) areas. This study aims to analyze the associations among Pb and Cd in blood, Th1/Th2 cytokines, and IgG subclasses in serum from children. A total of 181 healthy, 2- to 7-year-old children were examined. Of them, 104 were from Guiyu (e-waste exposed group), and the rest were from Haojiang (reference group) in China. Pb and Cd levels in whole blood, cytokines, and IgG subclasses in serum were determined. Exposed children had higher levels of blood Pb and Cd, serum IgG1, IgG1 + IgG2, serum Th1 cytokine interferon-γ (IFN-γ) and lower levels of the Th2 cytokine interleukin (IL)-13. Increased blood Pb levels were positively associated with serum levels of IFN-γ, and negatively associated with serum levels of IL-13. Adjusted linear regression analysis showed that serum levels of IL-13 were negatively associated with serum levels of IgG1 and IgG1 + IgG2. Mediation models indicated that IL-13 had significant mediating effects on the relationships between blood Pb levels and serum IgG1, as well as between blood Pb levels and serum IgG1 + IgG2. Increased blood Cd levels were positively associated with serum levels of IgG1. Our results show heavy metal (particularly Pb) exposure may affect IgG subclass production by regulating Th1/Th2 cytokines in exposed children, thus providing new evidence for a relationship between humoral immune function and environmental exposure.

A Graphene-Assembled Film Based MIMO Antenna Array with High Isolation for 5G Wireless Communication

With the development of 5G, Internet of Things, and smart home technologies, miniaturized and compact multi-antenna systems and multiple-input multiple-output (MIMO) antenna arrays have attracted increasing attention. Reducing the coupling between antenna elements is essential to improving the performance of such MIMO antenna system. In this work, we proposed a graphene-assembled, as an alternative material rather than metal, film-based MIMO antenna array with high isolation for 5G application. The isolation of the antenna element is improved by a graphene assembly film (GAF) frequency selective surface and isolation strip. It is shown that the GAF antenna element operated at 3.5 GHz has the realized gain of 2.87 dBi. The addition of the decoupling structure improves the isolation of the MIMO antenna array to more than 10 dB and corrects the antenna radiation pattern and operating frequency. The isolation between antenna elements with an interval of 0.4λ is above 25 dB. All experimental results show that the GAF antenna and decoupling structure are efficient devices for 5G mobile communication.

Human exposure to halogenated and organophosphate flame retardants through informal e-waste handling activities - A critical review

Informal electrical and electronic waste (e-waste) handling activities constitute a potentially important source of halogenated (HFRs) and organophosphate flame retardants (OPFRs) to the environment and humans. In this review, two electronic databases (ScienceDirect and Web of Science Core Collection) were searched for papers that addressed this topic. A total of 82 relevant studies (including 72 studies selected from the two databases and 10 studies located from the references of the first 72 selected studies) were identified that reported on human external and internal exposure to HFRs and OPFRs arising as a result of informal e-waste handling activities. Compared to the general population, higher levels of external exposure (i.e., inhalation, ingestion, and dermal absorption) and internal exposure (i.e., blood serum, hair, breast milk, urine, and other human matrices) to HFRs and OPFRs were identified for e-waste recyclers and residents inhabiting e-waste dismantling and recycling zones, especially for younger adults and children. Food intake and dust ingestion were the dominant exposure pathways for the majority of brominated flame retardants (BFRs) and dechlorane plus (DP); while inhalation was identified as the most significant pathway of human exposure to OPFRs in informal e-waste sites. The majority of research to date has focused on China and thus future studies should be conducted in other regions such as Africa and South Asia. Other suggested foci of future research are: examination of exposure via dermal contact with e-waste, dietary exposure of local populations to OPFRs, confirmation of the existence of and cause(s) of the higher body burdens of females compared with males amongst populations impacted by informal e-waste handling, and characterisation of exposure of such populations to chlorinated paraffins.

Cohort profile: China National Human Biomonitoring (CNHBM)-A nationally representative, prospective cohort in Chinese population

OBJECTIVE

Globally, developed countries such as the United States, Canada, Germany, Korea, have carried out long-term and systematic biomonitoring programs for environmental chemicals in their populations. The China National Human Biomonitoring (CNHBM) was to document the extent of human exposure to a wide array of environmental chemicals, to understand exposure profiles, magnitude and ongoing trends in exposure in the general Chinese population, and to establish a national biorepository.

METHODS

CNHBM adopted three-stage sampling method to obtain a nationally representative sample of the population. A total of 21,888 participants who were permanent residents in 31 provinces were designed to interviewed in this national biomonitoring (152 monitoring sites × 3 survey units × 2 sexes × 6 age groups × 4 persons = 21,888 persons) in 2017-2018. Unlike the US National Health and Nutrition Examination Survey, the CNHBM will follow the same participants in subsequent cycles allowing for dynamic, longitudinal data sets for epidemiologic follow-up. Each survey cycle of CNHBM will last 2 years and each subsequent cycle will occur 3 years after the prior cycle's completion.

RESULTS

In 2017-2018, the CNHBM created a large cohort of Chinese citizens that included districts/counties questionnaire, community questionnaire collecting information on villages/communities, individual questionnaire, household questionnaire, comprehensive medical examination, and collection of blood and urine samples for measurement of clinical and exposure biomarkers. A total of 21,746 participants were finally included in CNHBM, accounting for 99.4% of the designed sample size; and 152 PSUs questionnaires, 454 community questionnaires, 21,619 family questionnaires, 21,712 cases of medical examinations, 21,700 individual questionnaires, 21,701 blood samples and 21,704 urine samples were collected, respectively. Planned analyses of blood and urine samples were to measure both inorganic and organic chemicals, including 13 heavy metals and metalloids, 18 poly- and per-fluorinated alkyl substances, 12 phthalate metabolites, 9 polycyclic aromatic hydrocarbons metabolites, 4 environmental alkylated phenols, and 2 benzene metabolites.

CONCLUSIONS

CNHBM established the first nationally representative, prospective cohort in the Chinese population to understand the baseline and trend of internal exposure of environmental chemicals in general population, and to understand environmental toxicity.

Sequential recovery of gold and copper from bioleached wastewater using ion exchange resins

Numerous studies have sought to address the extraction of metals from printed circuit boards by employing bioleaching process. However, separation and recovery of the bioleached metals have always been a bottleneck. Herein, we demonstrate effective recovery of bioleached Au and Cu via selective separation using ion exchange resins. pH-edge experiments revealed high affinity of Amberjet™ 4200 resin towards Au (adsorption capacity > 98%) over the entire pH range from pH 2-10, whereas Amberlite IRC-86 resin recorded very high Cu adsorption at around pH 5. Therefore, a two-step sequential process was designed for the effective separation and recovery of Au and Cu. In the 1st step, Au was completely recovered by using the Amberjet™ 4200 at the natural pH of 7.5. Subsequently, the Au-free solution was adjusted to pH 5 and Cu was recovered by using Amberlite IRC-86 (2nd step). Consequently, 98.7% Au and 78.9% Cu were successfully recovered. Therefore, this study provides a technical guideline for the selective recovery of Au and Cu from bioleached wastewater, which promotes effective waste minimization and efficient resource recovery.

Environmental and health impacts due to e-waste disposal in China - A review

E-waste is discarded and shipped mostly to developing countries located in Asian continent for disposal from other developed countries. Especially 70% of the world's e-waste ends up in Guiyu, a small town located in Guangdong Province of China. As little as 25% is recycled in formal recycling centers with adequate protection for workers and the other e-waste arrived in those areas is not handled in organized manner. As per reports only roughly 12.5% of e-waste is actually recycled, and the recycling efforts in those regions are primitive and result in toxic substances being leached into the surrounding ecosystems. In addition to persistent organic pollutants, there are many heavy metals found in the ground and river sediments in Guiyu, exceeding the threshold set to protect human health. Those areas are no longer suitable for growing food, and water is unsafe for drinking, due to the amount of toxins leached into the groundwater and land. Hazardous threats to environment and human health due to hazardous substances of e-waste all around China, as well as the current e-waste management were documented in this review. The article concludes with controlled contamination sources, and eco-friendly and efficient remediation technologies to solve e-waste problem in China.

Global occurrence, chemical properties, and ecological impacts of e-wastes (IUPAC Technical Report)

The waste stream of obsolete electronic equipment grows exponentially, creating a worldwide pollution and resource problem. Electrical and electronic waste (e-waste) comprises a heterogeneous mix of glass, plastics (including flame retardants and other additives), metals (including rare Earth elements), and metalloids. The e-waste issue is complex and multi-faceted. In examining the different aspects of e-waste, informal recycling in developing countries has been identified as a primary concern, due to widespread illegal shipments; weak environmental, as well as health and safety, regulations; lack of technology; and inadequate waste treatment structure. For example, Nigeria, Ghana, India, Pakistan, and China have all been identified as hotspots for the disposal of e-waste. This article presents a critical examination on the chemical nature of e-waste and the resulting environmental impacts on, for example, microbial biodiversity, flora, and fauna in e-waste recycling sites around the world. It highlights the different types of risk assessment approaches required when evaluating the ecological impact of e-waste. Additionally, it presents examples of chemistry playing a role in potential solutions. The information presented here will be informative to relevant stakeholders seeking to devise integrated management strategies to tackle this global environmental concern.

A typical derivative and byproduct of tetrabromobisphenol A: Development of novel high-throughput immunoassays and systematic investigation of their distributions in Taizhou, an e-waste recycling area in eastern China

Environmental distribution and concentration of tetrabromobisphenol A bis- (2-hydroxyethyl) ether (TBBPA-DHEE) and tetrabromobisphenol A mono- (hydroxyethyl) ether (TBBPA-MHEE), are obscure due to the lack of available analytical methods. Here two novel immunoassays were established to systematically investigate their distributions in Taizhou, Eastern China. Five monoclonal antibodies against pollutants were generated with two designed haptens through animal immunization. After matched with different coating antigens/antibodies, ELISAs were established (LOD for TBBPA-DHEE, 0.12 ng/mL, based on OVA-M3/mAb-D4G6; LOD for TBBPA-MHEE, 0.79 ng/mL, based on OVA-M3/mAb-D2G6) and applied for investigation of their occurrences at a typical e-waste recycling area after 2-year samples collection, where the total 33 water, 32 soil and 16 biological samples were collected with the highest concentrations of 3.46 ng/mL, 2.76 ng/g (dry weight, dw) and 5.01 ng/g (dw), respectively. Meanwhile, our study also indicated that at the centralizing e-waste recycling sites the serious pollution for both chemicals still existed despite of various efforts. Besides, obvious improvements were observed at an abandoned e-waste recycling region treated and remedied for many years by the local Chinese government. These findings highlight the importance of policy decisions in treatment of pollutants to reduce organic pollutant-related health risks.