Distribution of PBDEs in air particles from an electronic waste recycling site compared with Guangzhou and Hong Kong, South China

Environmental impact of microplastics and potential health hazards

Microscopic plastic (microplastic) pollutants threaten the earth's biodiversity and ecosystems. As a result of the progressive fragmentation of oversized plastic containers and products or manufacturing in small sizes, microplastics (particles of a diameter of 5 mm with no lower limit) are used in medicines, personal care products, and industry. The incidence of microplastics is found everywhere in the air, marine waters, land, and even food that humans and animals consume. One of the greatest concerns is the permanent damage that is created by plastic waste to our fragile ecosystem. The impossibility of the complete removal of all microplastic contamination from the oceans is one of the principal tasks of our governing body, research scientists, and individuals. Implementing the necessary measures to reduce the levels of plastic consumption is the only way to protect our environment. Cutting off the plastic flow is the key remedy to reducing waste and pollution, and such an approach could show immense significance. This review offers a comprehensive exploration of the various aspects of microplastics, encompassing their composition, types, properties, origins, health risks, and environmental impacts. Furthermore, it delves into strategies for comprehending the dynamics of microplastics within oceanic ecosystems, with a focus on averting their integration into every tier of the food chain.

Unexpectedly high levels and health risks of atmospheric polychlorinated biphenyls in modern mechanical dismantling of obsolete electrical equipment: Investigations in a large integrated e-waste dismantling industrial estate

Large industrial estates for electrical and electronic waste (e-waste) mechanical dismantling and recycling are gradually replacing outmoded small factories and intensive domestic workshops for e-waste manual and chemical dismantling. However, the air pollution and health risks of persistent organic pollutants during the modern mechanical processing of e-waste, especially obsolete electrical equipment, still remain unclear. Here, unexpectedly high levels (409.3 ng/m3) and health risks of airborne polychlorinated biphenyls (PCBs) were found during the mechanical processing of obsolete electric equipment or parts in a large integrated dismantling industrial estate, which is comparable to or a dozen times higher than those reported during chemical processing. In contrast, the levels (936.0 pg/m3) and health risks of particulate polybrominated diphenyl ethers (PBDEs) were all lower than those of previous studies. PCB emissions (44.9-3300.5 ng/m3) varied significantly across six mechanical dismantling places specifically treating waste motors, electrical appliances, hardware, transformers, and metals, respectively. The high PCB content and mass processing number of obsolete electrical equipment probably result in the highest PCB emissions from the mechanical dismantling of obsolete motors, followed by waste electrical appliances and metals. The PCB non-cancer and cancer risks associated with inhalation and dermal exposure in different mechanical dismantling places were all above the given potential risk limits. In particular, the health risks of dismantling obsolete motor exceeded the definite risk levels. Little difference in PCB emissions and health risks between working and non-working time suggested the importance of PCB volatilization from most e-waste. Such high PCB emissions and health risks of PCBs undoubtedly posed a severe threat to frontline workers, but fortunately, they decreased significantly with the increasing distance from the industrial estate. We highlight that PCB emissions and associated health risks from obsolete electrical equipment with high PCB content during mechanical dismantling activities should be of great concern.

Deca-BDE emissions, validation, and environmental fate in China

Decabromodiphenyl ether (Deca-BDE) was officially listed in Annex A of the Stockholm Convention for persistent organic pollutants (POPs). It is necessary to establish its emission inventory to help reduce Deca-BDE contamination in the environment. We established a comprehensive Deca-BDE emission inventory in China. The results reveal that, from 2015 to 2017, the Deca-BDE emissions in its production source (source I) were less altered but increased annually in flame retarded plastics processing (source II), Deca-BDE-containing products usage (source III), and electronic waste (e-waste) treatment (source IV). We show that Deca-BDE emissions declined significantly in sources I and II but grew in source III and source IV from 2017 to 2018. We set up the provincial emission inventory to a gridded map on a spatial resolution of 0.25°× 0.25° latitude/longitude. The gridded inventory was incorporated into ChnMETOP model to simulate Deca-BDE concentrations in air and soil, and the modeled concentrations were compared to field-sampling data. The results show that the Deca-BDE emission inventory developed in this study agreed well with observed data, demonstrating that the Deca-BDE inventory in China developed in the present study is reliable. The inventory provides a support for quantifying human exposure risk to Deca-BDE and developing effective mitigation measures to mitigate Deca-BDE emissions.

Emission and environmental distribution of decabromodiphenyl ethane (DBDPE) in China from 2006 to 2026: Retrospection, forecasting, and implications for assessment and management

Decabromodiphenyl ethane (DBDPE) is the main alternative to decabromodiphenyl ether (deca-BDE) in commercial use. However, there is increasing evidence show that DBDPE is a potential persistent organic pollutant, and it has been found ubiquitously in environmental media across China in recent years. Monitoring studies have not been able to determine the overall levels and temporal trends of DBDPE contamination in China, and have been unable to explain how emission patterns can affect their environmental distribution. Therefore, this study estimated the temporal variance of DBDPE emissions and environmental concentrations in five regions of China from 2006 to 2026 using the PROduction-To-EXposure (PROTEX) mass balance model. The results showed that Guangdong Province was the greatest DBDPE pollution hotspot in China due to emissions from plastics manufacturing and e-waste disposal; there was also severe pollution in Shandong Province, where almost all the DBDPE in China is produced. The DBDPE concentrations in indoor and outdoor environments increased substantially in all regions during 2006-2021. Furthermore, in Guangdong Province and Shandong Province, the ratio of indoor/outdoor air concentrations was greater than or close to 1, indicative of significant outdoor emission sources of DBDPE. In contrast, the ratios for the Beijing-Tianjin-Hebei region, East China, and Southwest China were below 1 due to the indoor use of electronic equipment containing DBDPE. The temporal trends of these ratios indicated that DBDPE contamination has gradually spread from high-concentration environments with strong emission sources to low-concentration environments. The outcomes of this study have important implications for the risk assessment of DBDPE use in China and can be used to establish contamination-mitigation actions.

Environmental signature and health risk assessment of polybrominated diphenyl ethers (PBDEs) emitted from a landfill fire in Santiago de Chile

Polybrominated diphenyl ethers (PBDEs) have been flame retardants used in building materials, electronics, furnishings, vehicles, airplanes, plastics, polyurethane foams, and textiles for many years. Currently, the primary commercial mixtures, penta-, octa-, and deca-BDE, are globally restricted. Still, products containing PBDEs are expected to impact waste management and the environment for many years. In January 2016, an open fire in the Santa Marta landfill close to Santiago de Chile affected the city and surroundings. The fire caused several acute health effects and an increase in emergency hospitalizations. PBDE levels in the areas affected by the fire were determined in the air (gaseous and particulate), soil and the PBDE emissions were estimated using a dispersion model. The results showed an increase in the PBDE concentrations by a factor of 2-4 one day after the start of the fire. However, PBDE concentrations measured in PM₁₀ and the gas phase after the fire were considered low compared to other regions. Interestingly, PBDEs' patterns differed across the sites; however, BDE209 was the dominant congener for all environmental matrices. A preliminary risk assessment was conducted using the daily exposure dose (DED) by air inhalation estimation. The results showed low DED values for adults and children and suggested no direct health risk due to PBDE exposure. This study contributes new data useful for future solid waste management initiatives in the country.

The role of polybrominated diphenyl ethers in the induction of cancer: a systematic review of insight into their mechanisms

Environmental pollution caused by persistent organic pollutants (POPs) has increased the challenge for the scientific communities. Polybrominated diphenyl ethers (PBDEs), classified as POPs, are widely applied in various materials as brominated flame retardants (BFRs). Because of the nature of these chemical compounds including toxicity, stability, and capability to bioaccumulate and biomagnify, PBDEs have posed a great challenge and risk to human health and wildlife. Therefore, the side effects of exposure to PBDEs as ubiquitous pollutants in the environment on cancer progression were investigated using a systematic review (SR) survey. To achieve this goal, forty studies were considered after defining the search terms and inclusion criteria, and/or exclusion criteria; the eligible records were collected from the international bibliographic databases. Based on the findings of the reviewed records, environmental exposure to the BFRs including PBDEs has a positive association with different mechanisms that induce cancer progression. However, the findings of the reviewed studies were not totally consistent with the mode of action and side effects are yet to be fully elucidated. Several articles have reported that BFRs can be carcinogenic and induce epithelial to mesenchymal transition via different mechanisms. The main mode of action involved in the environmental exposure to BFRs and the risk of cancer progression is endoplasmic reticulum and oxidative stress (OS). Generally, the imbalance of antioxidant mechanisms, reactive nitrogen species (RNSs) and reactive oxygen species (ROSs), during damage in cells, and stress caused OS, which increases tumorigenesis via multiple mechanisms, such as DNA damage, inflammation, and angiogenesis.

Fungal biotechnology for urban mining of metals from waste printed circuit boards: A review

Rapid surge in electronic waste (e-waste) and its unscientific handling has an adverse impact on humans and the environment. Waste printed circuit board (WPCB), an integrated component of e-waste, has a high metallic content that includes both toxic and precious metals. Therefore, metal recovery is essential not just to avoid environmental degradation but also for economic growth. The current literature analysis focuses on one such eco-friendly approach, known as fungal biotechnology, for extracting metals from WPCBs. Among diverse bioleaching agents, fungi have shown promising metal extraction efficiency (Al: 65-96%; Co: 45-90%; Cu: 34-100%; Ni: 8-95%; Mn: 70-95%; Pb: 27-95%; Zn: 54-99%) and the ability to work in a wide pH range. However, in terms of metal recovery from WPCBs, fungal bioleaching has been less explored. This review, thus, assesses the fungal biotechnology for metal extraction from WPCBs and discusses the associated mechanism and kinetics involved. Different process parameters affecting the fungal bioleaching have also been discussed briefly. The review highlights that, while this process has enough potential, some associated drawbacks hinder its practical applicability on an industrial scale. Lastly, some suggestions for scaling up and reducing the cost of the process have been made, which need to be addressed.

Decadal Journey of E-Waste Recycling: What Has It Achieved?

E-waste recycling has been a hot topic around the world. This Feature revisits the issues raised by our previous Feature 10 years ago, i.e., the environmental, economic, and social benefits of e-waste recycling, using China as an example. The decadal journey of e-waste recycling has witnessed a giant leap from haphazard disposal initially to regulated disassembly presently. Specific successful stories include cleaned environment and reduced human exposure, significant advantages of urban mining over mineral mining, additional employment opportunities, and improved legislation system related to e-waste recycling. Strict legislation systems related to e-waste management based on the principle of Extended Producer Responsibility are key to the sustainable development of the e-waste recycling sector in China. The experiences and lessons learned in China would provide valuable guidelines for other developing countries.

Effect-directed analysis for revealing aryl hydrocarbon receptor agonists in sediment samples from an electronic waste recycling town in China

Exposure to electronic and electrical waste (e-waste) has been related to a few adverse health effects. In this study, sediment samples from an e-waste recycling town in China were collected, and aryl hydrocarbon receptor (AhR) agonists in the samples were identified using an effect-directed analysis (EDA) strategy. The CBG2.8D cell line reporter gene bioassay was used as a toxicity test, while suspect screening against chemical databases was performed for potential AhR agonist identification where both gas chromatography- and liquid chromatography-high resolution mass spectrometry analyses were run. When the original sample extract showed high AhR-mediated activity, sample fractionation was performed, and fractions exhibiting high bioactivity were chemically analyzed again to reveal the corresponding AhR agonists. In total, 23 AhR agonists were identified, including 14 commonly known ones and 9 new ones. Benzo [k]fluoranthene and 6-nitrochrysene were the dominant AhR agonists, covering 16-71% and 2.7-12%, respectively, of the AhR activation effects measured in the parent extracts. The newly identified AhR-active chemicals combined explained 0.13-0.20% of the parent extracts' effects, with 7,12-dimethylbenz [a]anthracene and 8,9,11-trimethylbenz [a]anthracene being the major contributors. A diagnostic isomer ratio analysis of polycyclic aromatic hydrocarbons suggested that the major source of AhR agonists identified in these e-waste related sediment samples were probably petroleum product combustion and biomass combustion. In the future, for a more comprehensive AhR agonist investigation, in-house chemical synthesis and purification, and, when necessary, a secondary sample fractionation, would be beneficial.

Tolerance of phyllospheric Wickerhamomyces anomalus to BDE-3 and heavy metals

Few research have focused on the potential microorganism and gene resources for plant resistance to polybrominated diphenyl ether (PBDE) and heavy metal (HM) co-contamination. The purpose of this study was to investigate the impact of phyllospheric Wickerhamomyces anomalus bioremediation ability on PBDE and HM co-contamination. The results showed that the toleration capability of W. anomalus to cadmium (Cd2+) was higher than that to chromium (Cr) or 4-bromodiphenyl ether (BDE-3) contamination. The threshold levels of W. anomalus tolerance to BDE-3, Cd2+, and Cr were 30 mg/L, 500 mg/L, 30 mg/L, respectively. The use of the higher concentration of BDE-3 (30 mg/L) as a carbon source may improve tolerance to Cd2+ and Cr (10 mg/L Cd2+ and 10 mg/L Cr). Overexpression of Wapdr15 gene of ABCG subfamily from W. anomalus improved the tolerance to BDE-3 (10 mg/mL) and Cd2+ (0.5 mg/mL) significantly in transgenic tobacco lines. The synergism effect of BDE-3 and Cd2+ stress existed similarly in W. anomalus and transgenic lines. The findings suggest that W. anomalus should be taken into account for providing an efficient method in improving crops' tolerance during PBDE and HM co-contamination in soil.

Pollution characteristics and risk assessment of air multi-pollutants from typical e-waste dismantling activities

This study investigated the characteristics of air multi-pollutants emitted during typical electronic waste (e-waste) dismantling processes and assessed their risks to the environment and human health. Concentrations of total volatile organic compounds (TVOCs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs) in a typical e-waste dismantling workshop were 137 μg/m³, 135 ng/m³ and 42 ng/m³, respectively, which were lower than those without emission control measures. The partial removal of pollutants due to the emission control measures also decreased the ozone formation potential and non-cancer risk of volatile organic compounds (VOCs). In the workshop, the lifetime cancer risk (LCR) of VOCs (8.1 × 10^-5) was close to the recommended values. Conversely, the LCR of PAHs (3.6 × 10^-5) and the total exposure index of PBDEs (19 ng/d) were remarkably lower than the recommended values of 10^-3 and that without emission control measures, respectively. Meanwhile, the concentrations of TVOCs, polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), PBDEs, and PAHs in the outlet were approximately 10-30 times higher than those in the workshop. In addition, the LCR of TVOCs within a 5-km radius area remained higher than the accepted value (10^-6), and the inhalation exposure risk of PCDD/Fs within a 20-km radius area was five times higher than the recommended value. Therefore, the emissions from e-waste recycling processes should be considered as an important source of air pollution, and more efficient control measures should be taken in the future.

Occurrence and Risk Assessment of Polybrominated Diphenyl Ethers in Surface Water and Sediment of Nahoon River Estuary, South Africa

The concentrations, potential sources, and compositional profile of PBDEs in the surface water and sediment of Nahoon Estuary, East London, South Africa, were investigated with solid-phase extraction and ultra-sonication, respectively, followed by gas-chromatography-electron capture detection. The seasonal range of the contaminants’ concentrations in water and sediment samples in spring season were ∑PBDE 329 ± 48.3 ng/L (25.32–785 ng/L) and ∑PBDE 4.19 ± 0.35 ng/g dw (1.91–6.57 ng/g), but ∑PBDE 62.1 ± 1.50 ng/L (30.1–110 ng/L) and ∑PBDE 65.4 ± 15.9 ng/g dw (1.98–235 ng/g) in summer, respectively. NH1 (first sampling point) was the most contaminated site with PBDE in the Estuary. The potential source of pollution is attributed to the stormwater runoff from a creek emptying directly into the Estuary. This study’s dominant PBDE congener is BDE-17, ranging from below detection limit to 247 ng/L and 0.14–32.1 ng/g in water and sediment samples, respectively. Most detected at all the sites were BDE-17, 47, 66, and 100. Most BDE-153 and 183 are found in sediment in agreement with the fact that higher brominated congeners of PBDE adsorb to solid materials. There was no correlation between the congeners and organic carbon and organic matter. However, the human health risk assessment conducted revealed that the PBDE concentration detected in the estuary poses a low eco-toxicological risk. Nevertheless, constant monitoring should be ensured to see that the river remains safe for the users, as it serves as a form of recreation to the public and a catchment to some neighbourhoods.

Opportunities and challenges in reducing personal inhalation exposure to air pollution among electronic waste recovery workers in Ghana

BACKGROUND

Informal sector electronic waste (e-waste) recovery produces toxic emissions resulting from burning e-waste to recover valuable metals.

OBJECTIVES

To identify high-risk worker groups by measuring relative levels of personal inhalation exposure to particulate matter (PM) of fine (≤2.5 µm) and coarse (2.5-10 µm) fractions (PM2.5 and PM2.5-10, respectively) across work activities among e-waste workers, and to assess how wind conditions modify levels of PM by activity and site location.

METHODS

At the Agbogbloshie e-waste site, 170 partial-shift PM samples and time-activity data were collected from participants (N = 105) enrolled in the GeoHealth cohort study. Personal sampling included continuous measures of size-specific PM from the worker's breathing zone and time-activity derived from wearable cameras. Linear mixed models were used to estimate changes in personal PM2.5 and PM2.5-10 associated with activities and evaluate effect modification by wind conditions.

RESULTS

Mean (±standard deviation) personal PM2.5 and PM2.5-10 concentrations were 80 (±  81) and 123 (± 139) µg m-3 , respectively. The adjusted mean PM2.5 concentration for burning e-waste was 88 µg m-3 , a 28% increase above concentrations during non-recovery activities (such as eating). Transportation-related and burning activities were associated with the highest PM2.5-10 concentrations. Frequent changes in wind direction were associated with higher PM2.5 concentrations when burning, and high wind speeds with higher PM2.5-10 concentrations when dismantling e-waste downwind of the burning zone.

Environmental contamination and public health effects of electronic waste: an overview

Purpose

In recent years, electronic waste has become the fastest growing waste stream globally with potential deleterious environmental and public health effects from its hazardous constituents. This review aims at providing an up-to-date information on the environmental and public health effects of e- wastes, and also identify research gaps that could form basis of further innovative studies on this important subject.

Methods

We carried out literature survey using several search engines. All available literature which reported directly on environmental contamination of air, soil, and water by e-wastes, and their effects on exposed plants, animals, and humans were used in other to generate an updated information.

Results

High production volume coupled with indiscriminate disposal and informal recycling has made electronic waste (e-waste) to become a global public and environmental health issue. E-waste is made up of different hazardous substances such as heavy metals and persistent organic pollutants with the capacity to contaminate the environment if processed or recycled inappropriately. Humans and animals become exposed to e-waste constituents via ingestion, inhalation, and dermal contact. Several health effects have been linked to e-wastes. The most susceptible were children, pregnant women, and workers in primitive recycling sites. Generation of e-waste is predicted to increase drastically in the next decade with the potential complex interactive effects of its constituents.

Conclusion

This review is an up-to-date assessment of studies and reports on e-waste environmental contamination and public health effects. The review has shown that e-waste contains constituents that caused adverse environmental effects and toxicity to the biota. However, there is an enormous data gap between exposure quantification and possible health effects. More studies are needed to elucidate and provide holistic information on environmental and public health dangers posed by e-waste constituents.

Cost-benefit analysis of metal recovery from e-waste: Implications for international policy

The e-waste problem needs be tackled under a global framework, based upon the understanding that e-waste is a global issue and thus a shared responsibility. To illustrate this point, a cost-benefit analysis of metal recovery from e-waste was conducted with Europe, North America and China as representative regions of e-waste producers. The final profit associated with the entire e-waste recycling process was estimated by deducing the energy costs of metal recovery from the revenues of the manually dismantling stage and the metal recovery stage. Then, the potential job opportunities were estimated based on the final profit from the local e-waste recycling and average wage per year. Overall, profits of manually dismantling 1 ton of e-waste varied widely, but the final profits were positive. The potential job opportunities generated by local e-waste recycling ranged from 4.65 × 10⁵ person/year for North America to 2.03 × 10⁶ for China person/year. According to our study, the environmental load of 1 kg of e-waste would be 1-9 USD, indicating that this is the cost required to offset the environmental consequences of each kilogram of e-waste. By applying environmental load to per capita, the concept can act as a tool to encourage countries to fairly share the environmental responsibility of e-waste based on their e-waste generation. Based on this, we propose an e-waste emissions trading system that set a cap on the total amount of e-waste that could be generated globally and per country, to reduce e-waste and carbon emissions.

Exposure to 4-bromodiphenyl ether during pregnancy blocks testis development in male rat fetuses

4-Bromodiphenyl ether (BDE3) is a photodegradation product of higher polybrominated diphenyl ether flame retardants and is known as an endocrine disruptor. However, it is unclear whether and how BDE3 affects the development of fetal testes. This study aimed to investigate the effect of in utero exposure to BDE3 on fetal testicular development in rats. From gestational day (GD) 12-21, BDE3 (0, 50, 100, and 200 mg/kg) was daily gavaged to female pregnant Sprague Dawley rats. BDE3 significantly reduced serum testosterone levels of male pups starting at 50 mg/kg. BDE3 reduced fetal Leydig cell number at a dose of 200 mg/kg without affecting fetal Leydig cell cluster frequency and Sertoli cell number. In addition, BDE3 down-regulated the expression of fetal Leydig cell genes (Cyp11a1, Hsd3b1, Cyp17a1, and Hsd17b3) and their proteins at 100 and/or 200 mg/kg. RNA-seq analysis showed that genes responsive to cAMP (Ass1, Gpd1, Rpl13a) were down-regulated and hypoxia-related genes (Egln3 and P4ha1) were up-regulated at 200 mg/kg. In utero exposure to BDE3 can promote autophagy and apoptosis of fetal Leydig cells via increasing the levels of Beclin1, LC3-II, BAX, and by decreasing the levels of p62 and BCL2. In conclusion, in utero exposure to BDE3 blocks the development of fetal rat testes.

Brominated flame retardants (BFRs) in PM2.5 associated with various source sectors in southern China

The present study investigates legacy and novel brominated flame retardants (BFRs) in atmospheric PM2.5 associated with various urban source sectors in a city and electronic waste (e-waste) recycling facilities in southern China. The concentrations of polybrominated diphenyl ethers (PBDEs) and novel BFRs (∑2NBFRs) at the urban industrial park (UIP) sites varied greatly from 22.0 to 105 pg m-3 and from to 29.7 to 459 pg m-3, respectively, and higher concentrations were generally found at sites involving industrial sectors of electronics, plastics, and machinery. Their spatial variations at other urban potential source sites were small suggesting a lack of strong point emissions. The levels of PBDEs and ∑2NBFRs at the e-waste facilities (220-2356 pg m-3 and 83.6-569 pg m-3) were significantly higher and did not temporally decline, indicating that improvement in e-waste recycling techniques does not significantly reduce emissions of PBDEs. NBFRs dominated the BFRs at the urban sites (55% on average), while PBDEs were still dominant (78%) at the e-waste sites. PBDE congener profiles in PM2.5 were substantially different from those in commercial mixtures. The congener profiles as well as their correlations suggested frequent formation of lower brominated PBDEs from degradation of highly brominated congeners in this region, which became appreciable due to the reduced emissions. The significant correlations among the lower brominated congeners also reflected similar environmental behaviors due to similar physicochemical properties.

Polybrominated diphenyl ethers and organochloride pesticides in the organic matter of air suspended particles in Mexico valley: A diagnostic to evaluate public policies

The presence of organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) was analysed in air particulate matter ≤ 2.5 μm (PM_2.5) and ≤10 μm (PM₁₀) collected in the Metropolitan Zone of Mexico Valley (MZMV), during 2013 and 2014, respectively. Spatial and seasonal distributions of PM and their organic content named solvent extracted organic matter (SEOM) were determined. PM mass concentration and SEOM/PM ratios were compared with previous studies in 2006 in Mexico City. PM_2.5 concentration was like found in 2006, however, PM₁₀ decreased ∼43%. The SEOM/PM₁₀ ratio was kept constant, suggesting a decrease in SEOM as well as PM₁₀ emitted from natural sources, probably as a result of changes in the land use due to urban growth. A decrease ∼50% SEOM/PM_2.5 ratio was observed in the same period, linked to adequate strategies and public policies applied by the local and federal governments to control the organic matter emitted from anthropogenic sources. Seven out of sixteen OCPs and five out of six PBDEs were found. The most common POPs were endosulfan I, endosulfan II, endosulfan sulfate, BDE-47 and BDE-99, present on >90% of the sampling days. OCPs in PM_2.5 and PBDEs in PM₁₀ showed seasonal variability. Higher PBDEs concentration in both particle sizes were observed at east and southeast of the MZMV, where one of the biggest landfills and wastewater treatment plants are located. OCPs in PM₁₀ were mainly emitted from agricultural areas located to the southwest, southeast and east of the MZMV. OCPs in PM_2.5 showed a regional contribution from the north and introduced into the valley. OCP degradation products were dominant over native OCPs, indicating no fresh OCP use. POPs comparison with other cities was made. Agreements and commissions created by the Mexican government reduced OCPs emissions, however, more effort must be made to control PBDE emission sources.

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.

Brominated flame retardants in home dust and its contribution to brominated flame retardants bioaccumulation in children hair

Brominated flame retardants (BFRs) in house dust have raised significant concern around the world. However, few studies have reported the correlation between BFR concentrations in house dust and children's hair samples. In this study, BFR concentrations in house dust and children's hair were measured. Chemical analysis showed that the total concentrations of polybrominated diphenyl ethers (PBDEs) in house dust ranged from 334 to 4444 ng g^-1, with a median of 442 ng g^-1, and the concentrations in children's hair ranged from 352 to 655 ng g^-1, with a median of 530 ng g^-1. In addition, two alternative flame retardants, pentabromoethylbenzene (PBEB) and hexabromobenzene, were frequently detected in house dust and human hair. BDE209 was the most abundant PBDE congener detected in both house dust and children's hair. A significant correlation was found between the integrated PCA score of BFR concentrations in house dust and in children's hair (r² = 0.31, P < 0.05), indicating the great contribution of house dust to the bodily burden of PBDEs in children. Risk assessment indicated that children's exposure to PBDEs via non-dietary intake of house dust should be recognized as an important exposure pathway.

Fate and migration of polybrominated diphenyl ethers in a workshop for waste printed circuit board de-soldering

Polybrominated diphenyl ethers (PBDEs) are released from the recycling process of PBDE-containing waste printed circuit board (WPCB), but studies on the mechanism of PBDE emission and migration are limited. In this study, PBDE concentrations in particulate matter (PM), dust, and fumes collected in a pilot-scale workshop for the WPCB de-soldering process were measured, and PBDE emission after gas treatment was estimated. The results showed that the mean concentrations of ∑₈PBDEs in TSP and PM_2.5 in the workshop were 20.3 ng/m³ (24.7 μg/g) and 16.1 ng/m³ (115 μg/g), respectively. In practice, the fumes containing gaseous and particulate PBDEs were treated by the combination of alkaline solution absorption and activated carbon adsorption. Compared to PBDE concentration in workshop floor dust (2680 ng/g), PBDE concentrations in solution scum (68,000 ng/g) and hood inside dust (20,200 ng/g) were condensed. The concentrations of ∑₆PBDEs at the stack outlet (416 pg/m³) after gas treatment were lower than those in the stack pipe (1310 pg/m³) and hood inside (7440 pg/m³). The PBDEs in fumes were removed through physical adsorption of alkaline solution and activated carbon, and solution scum constituted the main mass discharges of PBDEs. The emission factor of PBDEs at the stack outlet was 47.3 ng ∑₆PBDEs/kg WPCB. As a result, the WPCB de-soldering process is an important source of PBDE pollution, and gas treatment of solution absorption and activated carbon adsorption can reduce PBDE emission to some extent.

Determination of dry deposition velocity of polycyclic aromatic hydrocarbons under the sub-tropical climate and its implication for regional cycling

Atmospheric dry deposition is a major pathway for removal of polycyclic aromatic hydrocarbons (PAHs) from the atmosphere. Despite its significance in the atmospheric environment, measurements of the dry deposition velocity (V_DD) and deposition fluxes (F_DD) of PAHs are relatively limited. In this study, a passive dry deposition (PAS-DD) collector was co-deployed with passive air sampler polyurethane foam (PAS-PUF) from November 2015 to November 2016 in two major cities (Kathmandu and Pokhara), Nepal, to investigate the V_DD and F_DD of PAHs. The V_DD of PAHs ranged from 0.25 to 0.5 cm s^-1 and the annual average was recorded as 0.37 ± 0.08 cm s^-1. On the basis of measured V_DD, the F_DD of ∑15PAHs in Kathmandu and Pokhara were estimated as 66 and 5 kg yr^-1 respectively. According to the measured V_DD of Kathmandu and Pokhara in this study, and the previously published V_DD data of Toronto, Canada, where the same PAS-DD collector was used, a significant multi-linear correlation (r² = 0.79, p < 0.05) was found between V_DD of higher molecular weight (HMW with MW ≥ 228.3 and ≥ 4 rings) PAHs and meteorological parameters (precipitation and wind speed) and vapor pressure of PAHs. To the best of our knowledge, this enabled the development of an empirical model that can exhibit the combined effects of meteorological conditions on the V_DD of HMW PAHs. The model was used to estimate the V_DD values for major cities in the Indo-Gangetic Plain (IGP) region and the maximum estimated proportion of HMW PAHs deposited by dry deposition reached up to 60% of total emissions. Although PAH emissions in the IGP region pose global risks, the results of this study highlight the considerable risk for local IGP residents, due to the large dry deposition proportion of HMW PAHs.

Synthetic Chemical Trade as a Potential Driver of Global Health Disparities and Data Gaps on Synthetic Chemicals in Vulnerable Populations

PURPOSE OF REVIEW

Most research on toxic exposures in vulnerable populations focuses on air pollution. Synthetic chemical production, however, is a multi-billion-dollar industry that lacks appropriate international regulation to protect those exposed to toxic chemicals. This paper aims to describe the country-level import and export of key groups of synthetic chemicals using data from the United Nations Comtrade Database and provide a narrative review of the evidence from January 2018 to August 2019 on exposure to, health effects of, and interventions to reduce synthetic chemicals in vulnerable populations around the world.

RECENT FINDINGS

Generally, a small number of high-income countries export the majority of synthetic chemicals, while most low-income countries import more chemicals than they export, which may contribute to higher levels of synthetic chemicals in those settings. However, few studies have quantified exposures to synthetic chemicals in low- and middle-income countries, the health effects of such exposures, or interventions to mitigate exposures. Synthetic chemicals continue to enter markets despite our limited knowledge of their effects on human health, particularly in the most vulnerable populations. We need more research to understand the health impacts of these pervasive exposures.

Biodegradation of typical BFRs 2,4,6-tribromophenol by an indigenous strain Bacillus sp. GZT isolated from e-waste dismantling area through functional heterologous expression

Legacy wastewater contaminants from e-waste dismantling process such as 2,4,6-tribromophenol (TBP), one of the most widely used brominated flame retardants (BFRs), have raised concern owing to their toxicity and recalcitrance. Our previously isolated Bacillus sp. GZT from river sludge in e-waste dismantling area is a good candidate for bioremediation of BFRs contaminated sites considering its remarkable degradability of TBP and its intermediates. However, there exists a new challenge because bio-degrader cannot produce enough biomass or metabolic activity to cleanup TBP in practice complex environment. Here, we heterologously expressed and functionally characterized the genes and enzymes responsible for TBP degradation to examine the feasibility of enhancing the ability of this microorganism to detoxify TBP. Results demonstrated that five recombinant strains containing functional genes, designated tbpA, tbpB, tbpC, tbpD, and tbpE, become more tolerant toward a wide range of brominated compounds than the nontransgenic strain. Cytochrome P450 reductase encoded by tbpA gene could greatly increase efficiency to remove TBP (98.8%), as compared to wild-type strain GZT (93.2%). Its debromination intermediates 2,4-dibromophenol, 2,6-dibromo-4-methylphenol and 2-bromophenol were significantly metabolized by halophenol dehalogenases encoded by tbpB, tbpC, and tbpD, respectively. Finally, under the function of tbpE gene encoding enzyme, further debrominated product (phenol) was dramatically detoxified. To reduce the risk of these xenobiotics, the expression of these genes can be induced and significantly up-regulated during exposure to them. These results open broad scope for future study in developing genetic engineering technologies for more efficient remediation wastewater of e-waste recycling sites contaminated with TBP, which would certainly be important steps to lower TBP exposures and prevent potential health effects.

Polybrominated diphenyl ethers in the environment and human external and internal exposure in China: A review

Polybrominated diphenyl ethers (PBDEs) are widely used as brominated flame retardants. Because of their toxicity and persistence, some PBDEs were restricted under the Stockholm Convention in 2009. Since then, many studies have been carried out on PBDEs in China and in many other countries. In the present review, the occurrences and contamination of PBDEs in air, water, sediment, soil, biota and daily food, human blood, hair, and other human tissues in China are comprehensively reviewed and described. The human exposure pathways and associated health risks of PBDEs are summarized. The data showed no obvious differences between North and South China, but concentrations from West China were generally lower than in East China, which can be mainly attributed to the production and widespread use of PBDEs in eastern regions. High levels of PBDEs were generally observed in the PBDE production facilities (e.g., Jiangsu Province and Shandong Province, East China) and e-waste recycling sites (Taizhou City, Zhejiang Province, East China, and Guiyu City and Qingyuan City, both located in Guangdong Province, South China) and large cities, whereas low levels were detected in rural and less-developed areas, especially in remote regions such as the Tibetan Plateau. Deca-BDE is generally the major congener. Existing problems for PBDE investigations in China are revealed, and further studies are also discussed and anticipated. In particular, non-invasive matrices such as hair should be more thoroughly studied; more accurate estimations of human exposure and health risks should be performed, such as adding bioaccessibility or bioavailability to human exposure assessments; and the degradation products and metabolites of PBDEs in human bodies should receive more attention. More investigations should be carried out to evaluate the quantitative relationships between internal and external exposure so as to provide a scientific basis for ensuring human health.

Reductive debromination of decabromodiphenyl ether by iron sulfide-coated nanoscale zerovalent iron: mechanistic insights from Fe(II) dissolution and solvent kinetic isotope effects

The mechanism that iron sulfide-coated nanoscale zero valent iron (S-nZVI) has better reduction activity towards organic pollutants than nanoscale zero-valent iron (nZVI) has long been debated. In this work, a systematic study was investigated to compare differences of main influences, BDE-209 degradation pathway, degradation kinetics and reduction mechanism of BDE-209 between nZVI and S-nZVI systems. The observed transformation rate of BDE-209 (k_obs) by S-nZVI was 58.3 and 7.1 times greater than that by S^2- and nZVI, respectively. The valence change of Fe and S on S-nZVI surface before and after BDE-209 degradation process based on XPS characterization confirmed that both Fe⁰ and iron sulfide were the reduction entity of the surface-mediated reaction. The presence of tetrahydrofuran (THF) promoted the surface contact of BDE-209 with S-nZVI, thus accelerating the BDE-209 degradation process. Compared with nZVI, the iron sulfide coated on the Fe⁰ core surface could not only greatly reduce unnecessary electron loss via Fe⁰ corrosion with water, but also accelerate the transmission of electrons from Fe⁰ core to organic pollutants according to Fe(II) dissolution and solvent kinetic isotope effects investigations. These findings help to clarify the synergistic degradation mechanism between Fe⁰ core and iron sulfide shell layer.

Trends of electronic waste pollution and its impact on the global environment and ecosystem

Electronic waste (e-waste) is used for all electronic/electrical devices which are no more used. Conventionally, waste management policies are desfighandle the traditional waste. Although e-waste contains toxic materials, however, its management is rarely focused by policy makers; therefore, its negative impact on the global environment, ecosystem, and human health is aggravated. The review outlines the categories of e-waste materials, major pollutants including ferrous/non-ferrous metals, plastics, glass, printed circuit boards, cement, ceramic, and rubber beside, some valuable metals (such as copper, silver, gold, platinum). Toxic elements from e-waste materials, released in the air, water, and soil, include arsenic, cadmium, chromium, mercury, and lead, causing pollution. Although their roles in biological systems are poorly identified, however, they possess significant toxic and carcinogenic potential. It is therefore critical to monitor footprint and device strategies to address e-waste-linked issues from manufacturing, exportation, to ultimate dumping, including technology transmissions for its recycling. This review traces a plausible link among e-waste condition at a worldwide dimension, as far as settlement procedures to keep it secure and carefully monitored when traded. Their fate in the three spheres of the earth, i.e., water, soil, and air, impacts human health. The strategies and regulation to handle e-waste generation at the global level have been discussed. Graphical abstract .

WEEE Treatment in Developing Countries: Environmental Pollution and Health Consequences-An Overview

In the last few decades, the rapid technological evolution has led to a growing generation of waste electrical and electronic equipment (WEEE). Not rarely, it has been exported from industrialized to developing countries, where it represents a secondary source of valuable materials such as gold, copper, and silver. The recycling of WEEE is often carried out without any environmental and health protection. This paper reviews recent literature dealing with the informal treatment of WEEE in developing regions, gathering and analyzing data on concentration of both inorganic and organic pollutants in the environment. Open burning practices are revealed as most polluting ‘technology’, followed by mechanical treatment and leaching. Significant levels of pollutants have been detected in human bodies, both children and adults, working in or living in areas with informal WEEE treatment.

Temporal trends of polybrominated diphenyl ethers in the sediment cores from different areas in China

This paper presented the historical data on the temporal trends of polybrominated diphenyl ethers (PBDEs) in the sediment cores collected from the Huaihe River, Yellow River and Chaohu Lake, China. Among the 40 targeted PBDE congeners, only 10, 6, and 9 of them were detected respectively in the samples from the Huaihe River, Yellow River and Chaohu Lake. On average, the total PBDEs concentrations in sediments were highest in Chaohu Lake followed by the Huaihe River and the Yellow River. As compared to other PBDE congeners, BDE-209 had higher concentrations and detection rates. The similar down core variation between PBDEs and total organic carbon (TOC) suggests that TOC is an important factor influencing PBDEs distribution in the sediments. The total PBDEs concentrations showed an increasing trend from bottom to upper sediments before a decreasing trend in the topmost sediments. The rapid urbanization and industrialization of these regions in recent decades may cause the historically increasing concentrations of sedimentary PBDEs, especially BDE-209. The decreasing PBDEs concentrations in topmost sediments was probably related to the strict environmental policies at present.

Emission characteristics and exposure assessment of particulate matter and polybrominated diphenyl ethers (PBDEs) from waste printed circuit boards de-soldering

Heating processes for the removal of electronic components from waste printed circuit boards (WPCBs) is an important step in the chain of electronic waste recycling, and toxic fumes are generated during the de-soldering process, causing environmental pollution and posing health risks for the workers. This study is aimed to characterize emission and deposition fluxes of respirable particulate matter (PM), and assess exposure of workers to particle-bound polybrominated diphenyl ethers (PBDEs). An electrical low-pressure impactor was used to measure the real-time PM concentrations inside and outside the hood during the WPCBs de-soldering process. The results show that PM mass concentration inside the hood (204 mg/m³) was significantly higher than outside the hood (9.4 mg/m³), representing 95.4% PM removal by the hood. According to the International Commission on Radiological Protection model, the total deposition fluxes of PM in head airways region, tracheobronchial region, and alveolar region were determined as 1930, 74.0, and 123 μg/h, respectively. The deposition flux for coarse particles (2.5-10 μm) in the head airways was the largest (1830 μg/h), accounting for 86.1% of total PM deposited in respiratory system. The ∑₈PBDEs concentration in PM₁₀ inside the WPCBs de-soldering workshop was 20,300 pg/m³, and the ∑₈PBDEs inhalation exposure for the worker was 1.46 ng/kg/day. This study improves understanding of PM emission mechanisms and provides fundamental data for health assessments during WPCBs de-soldering process.

Polybrominated Diphenylethers (PBDEs) in ambient air samples at the electronic waste (e-waste) reclamation site

Polybrominated Diphenylethers (PBDEs) were used as flame-retardants in various building materials, plastic and other polymers, airplanes, electronics etc. All or some of their congeners have been already banned in many countries, due to their persistency and adverse health effects. In this study, we are focusing on the e-wastes as a source of emission of PBDEs in ambient air during reclamation processes. The ambient air particulate matter (PM) samples were collected at and near e-waste reclamation site in Bangkok, Thailand. Results showed the presence of various homologues viz: tri, tetra, penta, hexa, and hepta-PBDEs on both PM2.5 and Total Suspended Particle (TSP) samples. The comparison of samples as a function of distance from reclamation site indicated elevated levels of PBDEs in the close proximity to e-waste site. Interestingly, a shift in the congener pattern was observed with lower brominated PBDEs being more prevalent on nearby off-site samples as compared to the PM collected at the e-waste site. The total penta-PBDEs concentration is about double on e-waste site PM2.5 compared to control site samples. For TSP, tetra, penta, and hepta-PBDEs congeners are at higher concentrations at e-waste sites and its vicinity compared to reference sites. Overall, a clear trend can be observed indicating a debromination of PBDEs to more toxic tri and tetra congeners during reclamation process and PBDEs are being translocated from treated materials to ambient air PM. BDE 30 congener is identified as a specific marker of thermal reclamation processes of e-wastes as a most stable degradation product. This work indicates potential hazards related to the reclamation of e-wastes and remediation of sites containing PBDEs. In particular, thermal treatment methods can lead to congener transformation and increased emissions of more toxic lower-brominated congeners.

Impact of organic matter and meteorological factors on the long-term trend, seasonality, and gas/particle partitioning behavior of atmospheric PBDEs

We extended our knowledge of the impact of organic matter (OM) and meteorological factors on the long-term trend, seasonality and gas/particle partitioning behavior of polybrominated diphenyl ethers (PBDEs). In Lake Chaohu, PBDEs had an increasing trend, with a doubling time of 13.4 years at the urban site, and a decreasing trend, with a halving time of 6.1 years at the rural site. At the urban site, the negative association of OM with most congeners indicated that the graphene-like carbonaceous components might carry or release PBDEs, and the negative association of long-term rain fall and wind speed with most congeners was suggested to dilute or increase the transport speed of PBDEs in the atmosphere. At the rural site, the negative association with PM₁₀ and positive association with OM indicated that the PBDEs-buried OM was mainly from non-local sources. Restricted to the temperature seasonality, the frequency of PBDE congeners decreased with seasonality from 64% and 43% to 50% and 43% at the urban and rural sites, respectively. The slope of the simplified Pankow adsorption model in samples with larger absolute OM content (>10 μgC m^-3) was steeper than that with lower absolute OM content (<5 μgC m^-3), indicating that OM facilitated the gas-particle partitioning equilibrium. Interestingly, the theoretic partitioning coefficients were much lower than the measured ones for less brominated BDEs, whereas the highly brominated BDEs did the opposite. The theoretic partitioning coefficient should be further modified by considering the molecular weight distribution of the OM and the corresponding activity coefficients of the target compound in a specific type of OM phase.

Metal concentrations in pregnant women and neonates from informal electronic waste recycling

Electronic waste (e-waste) is the fastest growing solid waste stream worldwide and mostly ends up in developing countries where residents use primitive methods for recycling. The most infamous e-waste recycling town, Guiyu in Southeast China, has been recycling since the mid-1990s. E-waste contains several harmful chemicals, including lead (Pb), cadmium (Cd), chromium (Cr), and manganese (Mn). In 2011-12, the e-waste Recycling Exposures and Community Health (e-REACH) Study enrolled 634 pregnant women living in Guiyu and Haojiang, a control site, both in Shantou, China. The women completed a questionnaire and gave maternal blood, cord blood, and maternal urine, which were analyzed for Pb, Cd, Cr, and Mn. Maternal blood Pb, Cd, and Cr concentrations were significantly higher in Guiyu compared to Haojiang. In Guiyu, the geometric mean of Pb concentration in maternal blood was 6.66 µg/dL (range: 1.87-27.09 µg/dL) and was 1.74-fold greater than in Haojiang (95% CI: 1.60, 1.89). In cord blood, Pb concentration was 1.53-fold higher in Guiyu (95% CI: 1.38, 1.68). In maternal urine, Cd (ratio: 2.15, 95% CI: 1.72, 2.69) and Mn (ratio: 2.60, 95% CI: 2.04, 3.31) concentrations were significantly higher in Guiyu in comparison to Haojiang. In conclusion, pregnant women in Guiyu were at risk for increased exposure to heavy metals.

Trace metals in e-waste lead to serious health risk through consumption of rice growing near an abandoned e-waste recycling site: Comparisons with PBDEs and AHFRs

Despite the endeavour to eradicate informal e-waste recycling, remediation of polluted sites is not mandatory in many developing countries and thus the hazard of pollutants remaining in soil is often overlooked. It is noteworthy that a majority of previous studies only analysed a few pollutants in e-waste to reflect the impact of informal e-waste recycling. However, the actual impact may have been largely underestimated since e-waste contains various groups of pollutants and the effect of some emerging pollutants in e-waste remains unexplored. Thus, this study examined the contamination of metals, PBDEs and AHFRs in the vicinity of an abandoned e-waste recycling site. The accumulation and translocation of these pollutants in rice plants cultivated at the nearby paddy field were measured to estimate the health risk through rice consumption. We revealed that the former e-waste burning site was still seriously contaminated with some metals (e.g. Sn, Sb and Ag, I_geo > 5), PBDEs (I_geo > 3) and AHFRs (I_geo > 3), which can disperse to the nearby paddy field and stream. The rice plants can effectively absorb some metals (e.g. Mo, Cr and Mn, BCF > 1), but not PBDEs and AHFRs (BCF < 0.15), from soil and translocate them to the leaves. Alarmingly, the health risk through rice consumption was high primarily due to Sb and Sn (HQ > 20), whereas PBDEs and AHFRs had limited contribution (HQ < 0.08). Our results imply that abandoned e-waste recycling sites still act as the pollution source, jeopardising the surrounding environment and human health. Since some trace metals (e.g. Sb and Sn) are seldom monitored, the impact of informal e-waste recycling would be more notorious than previously thought. Remediation work should be conducted promptly in abandoned e-waste recycling sites to protect the environment and human health.

Characterization and Source Identification of Polybrominated Diphenyl Ethers (PBDEs) in Air in Xi'an: Based on a Five-Year Study

In order to assess polybrominated diphenyl ether (PBDE) atmospheric pollution levels in Xi’an, air samples were collected using a large flow air sampler from July 2008 to April 2013. In total, 134 samples were collected and 12 PBDE congeners were detected. Total PBDE concentrations (both gaseous and particulate phase) were 36.38–1054 pg/m³, with an average of 253.2 ± 198.4 pg/m³. BDE-209 was identified as the main PBDE component, with a corresponding concentration of 0.00–1041 pg/m³, accounting for 89.4% of total PBDEs. Principal component analysis results showed that PBDEs in Xi’an’s atmosphere mainly originated from commercial products containing penta-BDE, octa-BDE, and deca-BDE. The relative natural logarithm for partial pressure (RP) of PBDEs (gaseous phase) was calculated using the Clausius–Clapeyron equation. The gas flow trajectories at high, middle, and low RP values were analyzed by applying the backward trajectory model. These data indicated that the difference between trajectory distribution and concentration load on trajectories was huge under different RP values. PBDE concentrations (gaseous phase) weighted trajectory showed that the central and southwestern parts of Henan Province and the northwestern area of Hubei Province exhibited the darkest colors, and the daily average concentration contribution of PBDEs to the receiving point was >9 pg/m³, which indicates that these areas might be the main potential source areas of PBDEs in Xi’an’s atmosphere.

Air pollution and body burden of persistent organic pollutants at an electronic waste recycling area of China

This paper reviews the concentrations of persistent organic pollutants (POPs) in atmosphere of an electronic waste (e-waste) recycling town, Guiyu, in Southeast China, focusing on polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). We assess the evidence for the association between air pollution and human body burden, to provide an indication of the severity of respiratory exposure. Compared with standards and available existing data for other areas, it clearly shows that four typical POPs, derived from recycling processes, lead to serious atmospheric pollution and heavy body burden. From published data, the estimated respiratory exposure doses of Guiyu adults and children, varied between 2.48-10.37 and 3.25-13.6 ng kg^-1 body weight (bw) day^-1 for PBDEs, 2.31-7.6 and 4.09-13.58 pg World Health Organization-Toxic Equivalent Quantity (WHO-TEQ) kg^-1 bw day^-1 for PCDD/Fs, 5.57 and 20.52 ng kg^-1 bw day^-1 for PCBs, and 8.59-50.01 and 31.64-184.14 ng kg^-1 bw day^-1 for PAHs, respectively. These results show that air pollution is more harmful to children. Furthermore, except for PBDEs, the hazard quotient (HQ) of the other three pollutants was rated more than 1 by respiratory exposure only, and all of them are at risk of carcinogenesis. So we speculate these pollutants enter the body mainly through air inhalation, making respiratory exposure may be more important than dietary exposure in the Guiyu e-waste recycling area. Effective management policies and remediation techniques are urgently needed to prevent the deterioration of ambient air quality in the e-waste recycling area.

Particle-phase concentrations and sources of legacy and novel flame retardants in outdoor and indoor environments across Spain

Levels of particle-phase legacy polybrominated diphenyl ethers (PBDEs), and novel brominated and chlorinated flame retardants, such as decabromodiphenyl ethane (DBDPE) and Dechlorane Plus (DP), were measured in ambient outdoor air, indoor workplace air and indoor dust, in different locations across Spain. PBDE concentrations were generally higher in outdoor ambient air samples than in indoor air, ranging between 1.18 and 28.6 pg m^-3, while DP was the main flame retardant (FR) in indoor air (2.90-42.6 pg m^-3). A different behavior of legacy versus novel FRs was observed in all the environments and matrices considered, which seemed to indicate a progressive replacement of the former. Although the emission sources could not be fully identified, certain evidences suggested that high outdoor PBDE concentrations could be associated with old goods in landfills and recycling centers, while high indoor DP concentrations were linked to the presence of new electronic devices. A direct impact of land use on outdoor atmospheric DP concentrations was observed, with DP concentrations correlating with high density of buildings within a city. In addition, DP concentrations outdoors correlated with inorganic species with FR properties (e.g., Cr, Cu). Significant differences in the fraction of anti-DP to the total DP (F_anti ratio) were observed between indoor air (PM_2.5) and dust (PM₁₀), which could be related with: a) a dependence on particle size, suggesting a higher relative abundance of the anti-isomer in PM₁₀ than in PM_2.5, while similar concentrations were recorded for the syn-isomer; b) a higher deposition rate of the anti-isomer compared to the syn-isomer; and/or c) a more accentuated preferential degradation of the anti-isomer linked to artificial light or other agents coexisting in the air. The detectable presence of all the FR families analyzed in indoor air and dust points to the importance of monitoring these compounds in order to minimize human exposure.

A pilot study of metabolites of organophosphorus flame retardants in paired maternal urine and amniotic fluid samples: potential exposure risks of tributyl phosphate to pregnant women

Organophosphorus flame retardants (OPs) are of wide concern due to their presence in human urine and their considerable endocrine disruption and neuro-development toxicity. It has been confirmed that electronic waste (e-waste) dismantling activities have contributed to human exposure to OPs. However, assessments of OP exposure and the health risks for pregnant women and fetuses living in areas associated with e-waste dismantling have been impeded by a lack of data. In this study, six OP metabolites (mOPs) were measured in paired maternal urine and amniotic fluid samples collected from an e-waste dismantling area in Guangdong Province, China. All mOPs were detectable in maternal urine, whereas two were found in amniotic fluid. Dibutyl phosphate (DBP) was the predominant mOP in both maternal urine (geometric mean (GM): 2.9 ng ml-1) and amniotic fluid (1.3 ng ml-1); and diphenyl phosphate (DPHP) was the secondary one found (0.94 ng ml-1 in maternal urine, 0.12 ng ml-1 in amniotic fluid). The GM urinary concentrations of DBP and DPHP were two and seven times higher than those in amniotic fluid, respectively. The estimated daily intakes (EDIs) of triphenyl phosphate (TPHP) and tributyl phosphate (TnBP) by pregnant women were calculated from their daily urine excretion rate as fractions of OP metabolized to the corresponding metabolite (FUE). Our results showed high exposure levels to TPHP (median: 273 or 613 ng per kg bw per day) and TnBP (404 ng per kg bw per day) for pregnant women living in the e-waste associated area. Most importantly, 13% of mothers had EDITnBP levels that exceeded the reference dose (RfD: 2400 ng per kg bw per day), suggesting potential health risks from TnBP exposure for pregnant women living in areas associated with e-waste dismantling. This study, as a pilot study, presents the first measurements of mOPs in human amniotic fluid.

Brominated and organophosphate flame retardants along a sediment transect encompassing the Guiyu, China e-waste recycling zone

e-Waste recycling using crude techniques releases a complex, yet incompletely characterized mixture of hazardous materials, including flame retardants (FRs), to the environment. Their migration downstream and the associated risks also remain undocumented. We examined 26 FRs (18 brominated (BFRs: 12 polybrominated diphenyl ether (PBDE) congeners, plus 6 alternatives) and 8 organophosphate esters (OPEs)) in surficial sediments of the Lian River. Sampling encompassed the river's origin, through the Guiyu e-waste recycling zone, to its mouth, as well as associated tributaries. OPE exceeded BFR concentrations in most sediments, despite their far greater water solubilities. Among OPEs, tris(1-chloro-2-propyl) phosphate dominated upstream, but shifted to triphenyl phosphate in Guiyu and downstream sediments. For PBDEs, Deca-BDE dominated upstream, but Penta-BDE prevailed in Guiyu and at many downstream sites. Among emerging alternative BFRs, decabromodiphenyl ethane dominated upstream, transitioning to 1,2-bis(2,4,6,-tribromophenoxy)ethane in Guiyu sediments. Penta-BDE (BDE-47 + -99, 668-204,000 ng g^-1, ∑PBDEs 2280-287,000 ng g^-1), tetrabromobisphenol A (2,720-41,200 ng g^-1), 1,2-bis(2,4,6,-tribromophenoxy)ethane (222-9870 ng g^-1) and triphenyl phosphate (4260-1,710,000 ng g^-1, OPEs 6010-2,120,000 ng g^-1) concentrations in Guiyu sediments were among the highest reported in the world to date. The continuing dominance of these e-waste indicative FRs in sediments downstream of Guiyu suggested that FR migration from Guiyu occurred. Hazard quotients >1.0 indicated that the extreme sediment concentrations of individual FRs posed ecological risks in most Guiyu reach and downstream areas. Simultaneous exposure to multiple FRs likely increased risks. However, risks may be mediated if FRs were associated with strong sorbents, e.g. carbon black from burned debris, hydrophobic polymer fragments, or resided as additives within polymer fragments.

Concentrations and occupational exposure assessment of polybrominated diphenyl ethers in modern Chinese e-waste dismantling workshops

In this work, the concentrations of polybrominated diphenyl ethers (PBDEs) were determined in air, dust and fly ash samples from three legal waste electrical and electronic equipment dismantling plants with strict pollution controls. The risks posed by PBDEs to workers at the plants were assessed. The atmospheric concentrations of PBDEs in the different e-waste recycling workshops were 0.58-2.89 × 10³ ng/m³, and predominantly distributed in the particle phase (90.7%-99.9%). The concentrations of the PBDEs in the floor dust and fly ash samples from bag-type dust collectors in different workshops were 2.39-125 μg/g, 5.84-128 μg/g, respectively. The contributions of BDE-209 in air, floor dust and fly ash samples were 84.0%-97.9%, 11.2%-95.3% and 74.0%-94.9%, respectively, indicating that deca-BDE commercial formulations were their major sources. Daily exposure to PBDEs was also lower than has been found for workers in other recycling workshops. Human exposures to BDE-47, BDE-99, BDE-153, and BDE-209 were all below the levels considered to pose appreciable risks. Dust ingestion was the main exposure route for manual recyclers, and inhalation was the main exposure route for waste transportation workers. The results of this study indicate that PBDEs emissions and risks are lower in modern, legal e-waste recycling facilities with effective pollution controls. However, the effectiveness of the pollution controls need to be further researched in plastic crushing areas.

The brominated flame retardant BDE 47 upregulates purine metabolism and mitochondrial respiration to promote adipocyte differentiation

Adipocyte differentiation is closely associated with obesity and obesity-induced metabolic disorders. Epidemiological studies have demonstrated the association of obesity with environmental pollutants, such as polybrominated diphenyl ethers (PBDEs), common flame retardants in various consumer products. However, their obesogenic effects and mechanism are underexplored. We employed non-targeted metabolomics studies based on liquid chromatography-high resolution mass spectrometry to determine how 2,2',4,4'-tetra-brominated biphenyl ether (BDE 47), one of the main congeners of PBDEs detected in human tissue, promotes adipocyte differentiation of mouse preadipocyte 3 T3-L1 cells. The promoting effects of BDE 47 exposure (5 or 10 μM) on adipocyte differentiation were confirmed by enhancing lipid accumulation and expression levels of biomarkers of adipogenesis. For the first time, we demonstrated that BDE 47 upregulated purine metabolism and altered glutathione metabolism to promote oxidative stress and uric acid production in adipocytes. BDE 47 also elevated mitochondrial respiration and glycolysis in adipocytes to induce more ATP to combat oxidative stress. Antioxidant treatments, including the suppression of xanthine oxidase, inhibited the effects of BDE 47 on inducing oxidative stress and lipid accumulation. BDE 47 may be a potential environmental obesogen by providing a permissive oxidative environment to induce adipocyte differentiation.

E-waste in the international context - A review of trade flows, regulations, hazards, waste management strategies and technologies for value recovery

E-waste, or waste generated from electrical and electronic equipment, is considered as one of the fastest-growing waste categories, growing at a rate of 3-5% per year in the world. In 2016, 44.7 million tonnes of e-waste were generated in the world, which is equivalent to 6.1 kg for each person. E-waste is classified as a hazardous waste, but unlike other categories, e-waste also has significant potential for value recovery. As a result it is traded significantly between the developed and developing world, both as waste for disposal and as a resource for metal recovery. Only 20% of global e-waste in 2016 was properly recycled or disposed of, with the fate of the remaining 80% undocumented - likely to be dumped, traded or recycled under inferior conditions. This review paper provides an overview of the global e-waste resource and identifies the major challenges in the sector in terms of generation, global trade and waste management strategies. It lists the specific hazards associated with this type of waste that need to be taken into account in its management and includes a detailed overview of technologies employed or proposed for the recovery of value from e-waste. On the basis of this overview the paper identifies future directions for effective e-waste processing towards sustainable waste/resource management. It becomes clear that there is a strong divide between developed and developing countries with regard to this sector. While value recovery is practiced in centralised facilities employing advanced technologies in a highly regulated industrial environment in the developed world, in the developing world such recovery is practiced in a largely unregulated artisanal industry employing simplistic, labour intensive and environmentally hazardous approaches. Thus value is generated safely in the hi-tech environment of the developed world, whereas environmental burdens associated with exported waste and residual waste from simplistic processing remain largely in developing countries. It is argued that given the breadth of available technologies, a more systematic evaluation of the entire e-waste value chain needs to be conducted with a view to establishing integrated management of this resource (in terms of well-regulated value recovery and final residue disposal) at the appropriately local rather than global scale.

Emissions, environmental levels, sources, formation pathways, and analysis of polybrominated dibenzo-p-dioxins and dibenzofurans: a review

Polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) were labeled potential persistent organic pollutants by the Stockholm Convention and have structures and toxicities similar to those of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), which has caused considerable concern. This article reviews the current available literature on the status, sources, formation pathways, and analysis of PBDD/Fs. PBDD/Fs are widely generated in industrial thermal processes, such as those for brominated flame retardant (BFR) products, e-waste dismantling, metal smelting processes, and waste incineration. PBDD/Fs can form via the following routes: precursor formation, de novo formation, biosynthesis, and natural formation. The levels of PBDD/Fs in the environment and in organisms and humans have increased due to extensive consumption and the increasing inventory of BFRs; thus, the risk of human exposure to PBDD/Fs is expected to be high.

The occurrence of brominated flame retardants in the atmosphere of Gauteng Province, South Africa using polyurethane foam passive air samplers and assessment of human exposure

Polyurethane foam passive samplers were deployed between May 2016 and January 2017 to evaluate concentrations of polybrominated diphenyl ethers (PBDEs), selected alternative flame retardants (AFRs) and total hexabromocyclododecane (HBCDD) (sum of α-, β-, and γ-HBCDD). The PUF air samplers were deployed in semi-urban, urban, industrial and landfill sites in Gauteng Province, South Africa. The acquired results presented a clear semi urban-industrial-urban-landfill concentration gradient for all BFRs measured. Taking into account 2 sampling periods (cold and warm periods) (n = 16), the atmospheric concentrations of ∑₉PBDEs, HBCDDs and ∑AFRs were 100-2820 pg m^-3, 12-117 pg m^-3 and 41-4660 pg m^-3, respectively, for the sparsely populated residential area, densely populated residential area, industrial area and the landfill area. In all cases, BDE 47, 99, and 209 were the most dominant congeners with high detection frequencies. The highest calculated daily exposure dose in Gauteng Province atmosphere was 0.61 and 1.54 ng kg ^-1 - bw d ^-1 for adults and children respectively. The estimated total intake of PBDEs was 0.47-33.4 ng kg ^-1 - bw d ^-1, which was generally below the lowest adverse effect limit (LOAEL), suggesting that the residents of Gauteng Province may not be significantly affected as a result of their exposure to these pollutants through inhalation. However, this does not necessarily suggest that the pollutants are harmless to human health, since they have the tendency to bioaccumulate in biological systems. Incidentally, this is the first study from Africa to report on the atmospheric concentrations of PBDEs, HBCDDs and AFRs in urban, landfill and industrial areas. The findings from this study further highlight the contributory role of landfills as potential sources of BFRs into the atmosphere.

Amplification effect of haze on human exposure to halogenated flame retardants in atmospheric particulate matter and the corresponding mechanism

The health impact of haze is of great concern; however, few air quality studies have investigated trace pollutant contamination in the air. Size-segregated atmospheric particles (nine size fractions derived from PM₁₀) were collected in dwelling (indoor) and traffic (outdoor) environments in Xinxiang, China, during light pollution conditions (air quality index (AQI), 60-90) and heavy pollution conditions (AQI, 350-550), and they were analysed for halogenated flame retardants (HFRs), including polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs) and Dechlorane Plus (DP) isomers. HFR occurrence levels generally decreased in the order of PBDEs > NBFRs > DPs. The total mean abundance ratios of heavy pollution/light pollution were 4.0, 2.9, 4.4 and 3.6 for PBDEs, NBFRs, DPs and HFRs, respectively. Meteorological conditions played distinctive roles in the HFR distribution in the air. Apparent differences were found for the particle size distribution of HFRs under light and heavy pollution conditions. In general, for adults, the estimated hazard quotient (HQ) and incremental lifetime cancer risk (ILCR_BDE-209) values were approximately 1.7 × 10^-2 and 9.3 × 10^-9 in heavy pollution conditions, respectively, which were significantly higher than those in light pollution conditions (1.8 × 10^-3 and 2.1 × 10^-9, respectively).

Spatiotemporal variability of polybrominated diphenyl ether concentration in atmospheric fine particles in Shenzhen, China

Polybrominated diphenyl ethers (PBDEs) are widely used as flame retardants for various products and have become ubiquitous pollutants in environmental media. However, little is known about PBDE levels in Shenzhen, a manufacturing center of electronic products. This study aimed to investigate spatiotemporal variability of PBDE concentration in atmospheric fine particles (PM_2.5) and to estimate the daily inhalation exposure doses for local residents in Shenzhen, China. A total of 36 samples were collected and 8 PBDE compounds (BDE-28, 47, 99, 100, 153, 154, 183 and 209) were analyzed by isotope dilution high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS). Mean concentrations of Σ₈PBDEs and BDE-209 in PM_2.5 in Shenzhen were 33.47 pg/m³ and 24.75 pg/m³, respectively, which were lower than those for other reported cities from China. The mean concentration of Σ₈PBDEs was higher in the winter + spring than that in summer + autumn, and both concentrations of BDE-28 and BDE-47 in PM_2.5 were significantly higher in winter + spring than those in summer + autumn. Among the 8 congeners, BDE-209 was predominant, accounting for 73.9% of the Σ₈PBDEs concentrations. Traffic area, industrial area, residential area and discharge of electronic industries had significant positive influences on PBDE concentrations in PM_2.5. Both vegetation area and water area were significantly negatively correlated with PBDE levels in PM_2.5. Significantly negative correlation was also found between PBDE concentrations in PM_2.5 and the relative humidity. The ranking of estimated inhalation exposure doses of PBDEs via PM_2.5 inhalation were toddlers (1.74 pg/kg b.w./day) > children (1.33 pg/kg b.w./day) > adults (1.26 pg/kg b.w./day) > teenagers (0.64 pg/kg b.w./day), and toddlers had a highest risk to expose to PBDEs by PM_2.5. To our knowledge, the present study is the first to reveal the spatiotemporal variability of PBDEs in PM_2.5 of Shenzhen, China.

Elevated biomarkers of sympatho-adrenomedullary activity linked to e-waste air pollutant exposure in preschool children

Air pollution is a risk factor for cardiovascular disease (CVD), and cardiovascular regulatory changes in childhood contribute to the development and progression of cardiovascular events at older ages. The aim of the study was to investigate the effect of air pollutant exposure on the child sympatho-adrenomedullary (SAM) system, which plays a vital role in regulating and controlling the cardiovascular system. Two plasma biomarkers (plasma epinephrine and norepinephrine) of SAM activity and heart rate were measured in preschool children (n = 228) living in Guiyu, and native (n = 104) and non-native children (n = 91) living in a reference area (Haojiang) for >1 year. Air pollution data, over the 4-months before the health examination, was also collected. Environmental PM_2.5, PM₁₀, SO₂, NO₂ and CO, plasma norepinephrine and heart rate of the e-waste recycling area were significantly higher than for the non-e-waste recycling area. However, there was no difference in plasma norepinephrine and heart rate between native children living in the non-e-waste recycling area and non-native children living in the non-e-waste recycling area. PM_2.5, PM₁₀, SO₂ and NO₂ data, over the 30-day and the 4-month average of pollution before the health examination, showed a positive association with plasma norepinephrine level. PM_2.5, PM₁₀, SO₂, NO₂ and CO concentrations, over the 24 h of the day of the health examination, the 3 previous 24-hour periods before the health examination, and the 24 h after the health examination, were related to increase in heart rate. At the same time, plasma norepinephrine and heart rate on children in the high air pollution level group (≤50-m radius of family-run workshops) were higher than those in the low air pollution level group. Our results suggest that air pollution exposure in e-waste recycling areas could result in an increase in heart rate and plasma norepinephrine, implying e-waste air pollutant exposure impairs the SAM system in children.