Polybrominated diphenyl ethers in leaves and soil from typical electronic waste polluted area in South China

Informal E-waste recycling practices and environmental pollution in Africa: What is the way forward?

Globally, e-waste is the fastest growing and most valuable waste-stream. While countries worldwide are increasingly acknowledging the e-waste problem and introducing policies and regulations that deal with e-waste, large quantities of e-waste still go undocumented. Much of these global e-wastes are accumulating in open-dumpsites and landfills in African-countries where they are recycled informally resulting in significant environmental and public-health concerns. Although, there is a plethora of studies on e-waste management and disposal, only a few-studies have focused on African-countries who are major recipients of e-waste. Moreover, despite the attempts to mitigate the problem of e-waste in African-countries, e-waste has remained a major-concern and there are currently very limited workable solutions. This study examines informal e-waste recycling, environmental pollution and the extent of environmental and health impacts in major countries of concern including Ghana, Nigeria, Egypt, Kenya and South Africa. The global e-waste Waste Atlas Report, 2020 identified these countries as major recipients of e-waste. To achieve the aims of this research, previous studies from 2005 to 2022 are collected from various databases and analyzed. Accordingly, this study focuses on environmental pollution and public-health impacts resulting from e-waste dumping and informal recycling practices, illegal transboundary shipment of e-waste to the selected countries, and the interventions of governments and international organizations in reducing the impact of e-waste pollution and informal recycling practices in Africa. Based on the outcomes of this study, practical approaches on the way-forward are recommended. The findings of this study contribute to a growing-body of research on informal e-waste recycling practices in Africa to document that individuals working within e-waste sites and residents in nearby communities are exposed to a number of toxic-substances, some at potentially concerning levels.

Polybrominated Diphenyl Ether Quinone Exposure Induces Atherosclerosis Progression via CD36-Mediated Lipid Accumulation, NLRP3 Inflammasome Activation, and Pyroptosis

Polybrominated diphenyl ethers (PBDEs) are used worldwide in brominated flame retardants. Although due to the forbiddance of their application, PBDEs continuously exist in the environment due to their persistence. Therefore, it is important to expand the understanding of their potential toxicities and human risks. The underlying cardiovascular toxicological mechanisms of PBDEs are still largely unknown. Our previous studies indicated that PBDE quinone-type metabolite (PBDEQ) exposure causes reactive oxygen species (ROS)-driven cytotoxicity and various types of programmed cell death. Here, we first reported PBDEQ exposure induces atherosclerosis progression in bone marrow-derived macrophages (BMDMs) isolated from wild-type C57BL/6 or CD36-/- mice and J774A.1 macrophage models. First, we found that PBDEQ exposure induced lipid accumulation in oxidized low-density lipid (Ox-LDL)-treated J774A.1 macrophages. Consistently, in J774A.1 macrophages, PBDEQ exposure resulted in NLR family pyrin domain containing 3 (NLRP3) inflammasome activation and pyroptosis. CD36, a scavenger receptor responsible for the mediation of Ox-LDL uptake, was upregulated upon PBDEQ treatment. On the contrary, genetic knockout of CD36 or CD36 silencing by small interfering RNA efficiently attenuates PBDEQ-promoted lipid accumulation in BMDMs and J774A.1 macrophages. These findings highlight the effect of CD36 on the cardiovascular toxicity of PBDEs, which provides a better understanding of the pro-atherosclerosis effect of PBDEs.

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.

Polybrominated Diphenyl Ethers and Heavy Metals in a Regulated E-Waste Recycling Site, Eastern China: Implications for Risk Management

Serious pollution of multiple chemicals in irregulated e-waste recycling sites (IR-sites) were extensively investigated. However, little is known about the pollution in regulated sites. This study investigated the occurrence of 21 polybrominated diphenyl ethers (PBDEs) and 10 metals in a regulated site, in Eastern China. The concentrations of PBDEs and Cd, Cu, Pb, Sb, and Zn in soils and sediments were 1-4 and 1-3 orders of magnitude lower than those reported in the IR-sites, respectively. However, these were generally comparable to those in the urban and industrial areas. In general, a moderate pollution of PBDEs and metals was present in the vegetables in this area. A health risk assessment model was used to calculate human exposure to metals in soils. The summed non-carcinogenic risks of metals and PBDEs in the investigated soils were 1.59-3.27 and 0.25-0.51 for children and adults, respectively. Arsenic contributed to 47% of the total risks and As risks in 71.4% of the total soil samples exceeded the acceptable level. These results suggested that the pollution from e-waste recycling could be substantially decreased by the regulated activities, relative to poorly controlled operations, but arsenic pollution from the regulated cycling should be further controlled.

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.

Metabolomics and transcriptomics reveal defense mechanism of rice (Oryza sativa) grains under stress of 2,2',4,4'-tetrabromodiphenyl ether

2,2',4,4'-Tetrabromodiphenyl ether (BDE-47), a predominant polybrominated diphenyl ether (PBDE), has received extensive attention for its potential environmental impact. An integrated study of metabolomics and transcriptomics was conducted on two rice (Oryza sativa) cultivars, Lianjing-7 (LJ-7) and Yongyou-9 (YY-9), which have been identified as tolerant and sensitive cultivars to BDE-47, respectively. The objective was to investigate the molecular mechanisms of their different ability to tolerate BDE-47. Both rice plants were cultivated to maturity in soils containing three concentrations of BDE-47 (10, 20, and 50 mg/kg). Metabolomic analyses of rice grains identified 65 metabolites in LJ-7 and 45 metabolites in YY-9, including amino acids, saccharides, organic acids, fatty acids, and secondary metabolites. In the tolerant cultivar LJ-7 exposed to 50 mg/kg BDE-47, concentrations of most of the metabolites increased significantly, with α-ketoglutaric acid increased by 20-fold and stigmastanol increased by 12-fold. In the sensitive cultivar YY-9, the concentrations of most metabolites increased after the plant was exposed to 1 and 10 mg/kg BDE-47 but decreased after the plant was exposed to 50 mg/kg BDE-47. Transcriptomic data demonstrated that regulation of gene expressions was affected most in LJ-7 exposed to 50 mg/kg BDE-47 (966 genes up-regulated and 620 genes down-regulated) and in YY-9 exposed to 10 mg/kg BDE-47 (85 genes up-regulated and 291 genes down-regulated), in good accordance with the observed metabolic alternation in the two cultivars. Analyses of metabolic pathways and KEGG enrichment revealed that many biological processes, including energy consumption and biosynthesis, were perturbed in the two rice cultivars by BDE-47. A majority of metabolites and genes involved in dominating pathways of energy consumption (e.g., tricarboxylic acid cycle) and the biosynthesis (e.g., metabolism of saccharides and amino acids) were enhanced in LJ-7 by BDE-47. In contrast, energy consumption was increased while biosynthetic processes were inhibited in YY-9 by BDE-47, which could lead to the sensitivity of YY-9 to BDE-47. The combined results suggest that the different defensive abilities of these two rice cultivars in response to BDE-47 could be attributed to their differences in energy-consumption strategy and biosynthesis of nutritional components in grains. This study provides a useful reference for rice cultivation in PBDE-polluted areas.

The occurrence of polybrominated diphenyl ether (PBDE) contamination in soil, water/sediment, and air

As a kind of brominated flame retardants (BFRs), polybrominated diphenyl ethers (PBDEs) are extensively used in different types of electronic equipment, furniture, plastics, and textiles. PBDEs are ubiquitous environmental contaminants that may impact human health and ecosystems. Here we highlight recent findings on the occurrence, contamination status, and transport of PBDEs in soil, water/sediment, and air. Four aspects are discussed in detail: (1) sources of PBDEs to the environment; (2) occurrence and transport of PBDEs in soil; (3) PBDEs in aquatic ecosystems (water/sediment) and their water-sediment partitioning; and (4) the occurrence of PBDEs in the atmosphere and their gas-particle partitioning. Future prospects for the investigation on PBDEs occurrence are also discussed based on current scientific and practical needs.

In vitro mutagenicity and genotoxicity of raw and simulated leachates from plastic waste dumpsite

Increase in production of different types of plastics has led to increase in the amount of plastic waste generation worldwide. The chemical constituents of these plastic wastes have made their disposal an important economic and environmental health problem globally. This study assessed the mutagenic and genotoxic potential of plastic waste dumpsite raw and simulated leachates using the Ames Salmonella fluctuation test with Salmonella typhimurium strains TA98 and TA100, and the SOS chromotest with Escherichia coli PQ37. Physico-chemical parameters and organic constituents of the leachates were also analyzed. The result of the Ames test showed that the leachates are mutagenic even at low concentration. Also, the TA100 strain was the more responsive strain in terms of mutagenic index in the absence of metabolic activation. The SOS chromotest results complimented the Ames Salmonella fluctuation test results. Nevertheless, the E. coli PQ37 system was slightly more sensitive than the Salmonella assay for detecting mutagens and genotoxins in the tested leachates. Generally, simulated leachate showed a higher mutagenicity and genotoxicity than the raw leachate. Pb, Cd, Cr, Ni, Cu, As, PBDEs, PAHs, PCBs, and Bisphenol A contents analyzed in the leachates were believed to play significant role in the observed mutagenicity and genotoxicity in the microbial assays. These data showed that plastic waste constituents are capable of inducing DNA damage in exposed organisms and might induce similar damage in plants, animals and humans exposed to it, hence, great care should be taken to eliminate indiscriminate disposal of plastics in the environment.

Critical review of soil contamination by polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs); concentrations, sources and congener profiles

Polybrominated diphenyl ethers (PBDEs) have been used in a broad array of polymeric materials such as plastics, foams, resins and adhesives to inhibit the spread of fires since the 1970s. The widespread environmental contamination and well documented toxic effects of PBDEs have led to bans and voluntary withdrawals in many jurisdictions. Replacement novel brominated flame retardants (NBFRs) have, however, exhibited many of the same toxic characteristics as PBDEs and appear to share similar environmental fate. This paper presents a critical review of the scientific literature regarding PBDE and NBFR contamination of surface soils internationally, with the secondary objective of identifying probable pollution sources. An evaluation of NBFR distribution in soil was also conducted to assess the suitability of the newer compounds as replacements for PBDEs, with respect to their land contamination potential. Principle production of PBDEs and NBFRs and their consequent use in secondary polymer manufacture appear to be processes with strong potential to contaminate surrounding soils. Evidence suggests that PBDEs and NBFRs are also released from flame retarded products during disposal via landfill, dumping, incineration and recycling. While the land application of sewage sludge represents another major pathway of soil contamination it is not considered in this review as it is extensively covered elsewhere. Both PBDEs and NBFRs were commonly detected at background locations including Antarctica and northern polar regions. PBDE congener profiles in soil were broadly representative of the major constituents in Penta-, Octa- and Deca-BDE commercial mixtures and related to predicted market place demand. BDE-209 dominated soil profiles, followed by BDE-99 and BDE-47. Although further research is required to gain baseline data on NBFRs in soil, the current state of scientific literature suggests that NBFRs pose a similar risk to land contamination as PBDEs.

Occurrence, composition, source, and regional distribution of halogenated flame retardants and polybrominated dibenzo-p-dioxin/dibenzofuran in the soils of Guiyu, China

Guiyu, China, is well-known for the crude disposal of electronic waste (EW) and severe persistent organic pollutants (POPs). Therefore, in this study, the occurrence, composition, and source of polybrominated diphenyl ethers (PBDEs), 2,2',4,4',5,5'-hexabromobiphenyl (BB153), some novel brominated flame retardants (NBFRs), Dechlorane Plus (DP) and polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs) in farmland soils covering Guiyu were studied. In EW disposal area soils, PBDEs were the most abundant FRs, with concentrations of 13-1014 ng g^-1. The primary PBDE sources were technical Penta- and Deca-BDE mixtures in northern and southern Guiyu, respectively. The levels of BB153 were relatively low, possibly because it has been banned in the 1970s. The concentrations of hexabromobenzene (HBB) were 0.048-3.3 ng g^-1, while pentabromoethylbenzene (PBEB) was almost not detected in the soils. Two alternatives to commercial PBDEs, decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), were the primary NBFRs, with concentrations of 1.8-153 ng g^-1 and 0.43-15 ng g^-1, respectively. DP was another primary FR, with concentrations of 0.57-146 ng g^-1. Moreover, syn-DP and anti-DP isomers were not stereoselectively decomposed during the EW disposal process and were therefore present in their original fractions in the soils. The levels of PBDD/Fs in EW disposal area soils were 2.5-17 pg TEQ g^-1. 1,2,3,4,6,7,8-HpBDF and OBDF were the dominant congeners, mainly derived from processing, pyrolysis and combustion of BFRs. The regional distribution of pollutants was shown to be related to the disposal manner of EW, with their open thermal disposal tending to release more highly brominated compounds such as BDE209, DBDPE, and 1,2,3,4,6,7,8-HpBDF. Additionally, some riverbank sites were heavily polluted because of nearby point sources, downwind Simapu (SMP) town without EW disposal activity was also contaminated by these pollutants.

Excellently reactive Ni/Fe bimetallic catalyst supported by biochar for the remediation of decabromodiphenyl contaminated soil: Reactivity, mechanism, pathways and reducing secondary risks

Ni/Fe bimetallic nanoparticles were synthesized using biochar as a support (BC@Ni/Fe) and their effectiveness in removing BDE209 from soil was investigated. BET, SEM, TEM, XPS and FTIR were used to characterize the catalyst, and the efficiencies of biochar, Ni/Fe nanoparticles and BC@Ni/Fe for removing BDE209 from soil were compared. The results showed that Ni/Fe bimetallic nanoparticles highly dispersed in the biochar, reducing its agglomeration. Thus, the reaction activity of BC@Ni/Fe was increased. The removal efficiency of BDE209 by BC@Ni/Fe was 30.2% and 69% higher than that by neat Ni/Fe and biochar, respectively. Meanwhile, an enhanced degradation efficiency of PBDEs in soil was realized by monitoring the formation of Br^- ions with time in the system. In addition, the degradation products identified by GC-MS showed that the reductive degradation of BDE209 proceeded through stepwise or multistage debromination, for which the degradation pathways and removal mechanisms were speculated. Furthermore, BC@Ni/Fe reduced the bioavailability of metals in soil and adsorbed the degradation products of BDE209, representing an improvement over neat Ni/Fe nanoparticles for the remediation of PBDEs-contaminated soil.

Characterization of anthropogenic impacts in a large urban center by examining the spatial distribution of halogenated flame retardants

Anthropogenic impacts have continuously intensified in mega urban centers with increasing urbanization and growing population. The spatial distribution pattern of such impacts can be assessed with soil halogenated flame retardants (HFRs) as HFRs are mostly derived from the production and use of various consumer products. In the present study, soil samples were collected from the Pearl River Delta (PRD), a large urbanized region in southern China, and its surrounding areas and analyzed for a group of HFRs, i.e., polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane, bis(hexachlorocyclopentadieno)cyclooctane (DP) and hexabromobenzene. The sum concentrations of HFRs and PBDEs were in the ranges of 0.66-6500 and 0.37-5700 (mean: 290 and 250) ng g(-1) dry weight, respectively, around the middle level of the global range. BDE-209 was the predominant compound likely due to the huge amounts of usage and its persistence. The concentrations of HFRs were greater in the land-use types of residency, industry and landfill than in agriculture, forestry and drinking water source, and were also greater in the central PRD than in its surrounding areas. The concentrations of HFRs were moderately significantly (r(2) = 0.32-0.57; p < 0.05) correlated with urbanization levels, population densities and gross domestic productions in fifteen administrative districts. The spatial distribution of DP isomers appeared to be stereoselective as indicated by the similarity in the spatial patterns for the ratio of anti-DP versus the sum of DP isomers (fanti-DP) and DP concentrations. Finally, the concentrations of HFRs sharply decreased with increasing distance from an e-waste recycling site, indicating that e-waste derived HFRs largely remained in local soil.

Polybrominated diphenyl ethers in air and fallouts from an e-waste polluted region in southeast China: insight into levels, compositional profiles, and seasonal variation

Air and fallout samples were collected seasonally in an e-waste polluted region in southeast of China in 2013-2014. The annual polybrominated diphenyl ethers (PBDEs) concentrations in air and fallout samples were 200 ± 162 pg m(-3) and 320 ± 255 ng g(-1), respectively. The deposition flux calculated from the fallout concentration was 110 ± 77.3 ng m(-2) day(-1). The PBDE levels and deposition fluxes of the samples deployed within the e-waste central area were three to four times higher than those in the surrounding area. The congener profiles in the air samples could be commonly found in commercial penta-BDE mixtures. BDE209 was the most dominant congener in fallout samples. Debromination processes were confirmed to occur both in the air and fallouts due to the minor amounts or inexistence of some congeners in technical PBDE products. The highest gaseous PBDE concentration was found during the summer while lowest during the autumn. PBDE concentration in fallouts turned up higher in the cold months while lower in the warm months. The similarity of deposition fluxes at sites in the e-waste central area indicated a steady PBDE emission source, whereas the significant relationship between deposition fluxes and particle weights at sites in the e-waste surrounding area suggested the scavenging of PBDEs in this area was largely associated with particles.

Bioaccumulation and translocation of polyhalogenated compounds in rice (Oryza sativa L.) planted in paddy soil collected from an electronic waste recycling site, South China

The bioaccumulation and translocation of polyhalogenated compounds (PHCs) in rice planted in the paddy soils of an electronic waste (e-waste) recycling site were investigated, along with the effect of contaminated soils on rice growth. The PHCs included polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), and dechlorane plus (DPs). The morphological development and all measured physiological parameters of rice plants except for peroxidase were significantly inhibited by e-waste contaminated soils. Specifically, soil-root bioaccumulation factors (RCFs) increased with increasing logarithm of octanol-water partition coefficient (logKow) for PCBs, but decreased for PBDEs. During translocation from root to stem, translocation factors (TFs) and logKow were positively correlated. However, the accumulation mechanism in the leaf was concentration-dependent. In the high concentration exposure group, translocation play more important role in determination PHCs burden in leaf than atmospheric uptake, with logTF (from stem to leaf) being positively correlated with logKow. In contrast, in the low exposure and control groups, logTF (from stem to leaf) was negatively correlated with logKow. In addition, Syn-DP was selectively accumulated in plant tissues. In conclusion, this study demonstrates that e-waste contaminated soils affect rice growth, revealed the rule of the bioaccumulation and translocation of PHCs in rice plants.

Changes of polybrominated diphenyl ether concentrations in ducks with background exposure level and time

To reveal what degree bioaccumulation of polybrominated diphenyl ethers (PBDEs) depends on exposure time and other factors, we conducted a semi-field experiment for a year (June 2008-June 2009) in a village in an e-waste recycling site in Taizhou, China. Approximately one hundred of juvenile ducks (Anas domestica Linnaeus) were entrusted to a villager. The ducks lived and forged in a PBDE-polluted pond from the late March to the end of November. Fish and mudsnails that were heavily polluted by PBDEs were main food. In cold days (from December to the middle March), the ducks lived in the villager' house, and mainly fed on paddy, which contained lower concentrations of PBDEs than fish and mudsnails. The female ducks were sampled for PBDE analysis every three months. We found that the ∑PBDE concentrations in duck liver, muscle, lung and brain fluctuated greatly with the changes of exposure levels that were determined by the environment and diets, but the ∑PBDE concentrations in fat tissue increased successively with time. Congener analysis demonstrated that the successive increase in the ∑PBDE concentrations with time in fat tissue was due to the successive increase in BDE-209, -183 and -153 concentrations, with large fluctuations of low brominated congeners. The results show that PBDE concentrations in liver, muscle, lung and brain tissues heavily depends on exposure levels rather than exposure time. In fat tissue, by contrast, PBDE concentrations (mainly high brominated congeners) slightly depends on exposure levels but heavily depend on time relative to other tissues, implying that high brominated congeners seem to have longer half-lives than low brominated congeners in fat tissue.

Polybrominated diphenyl ethers in e-waste: level and transfer in a typical e-waste recycling site in Shanghai, Eastern China

Very few data for polybrominated diphenyl ethers (PBDEs) were available in the electronic waste (e-waste) as one of the most PBDEs emission source. This study reported concentrations of PBDEs in e-waste including printer, rice cooker, computer monitor, TV, electric iron and water dispenser, as well as dust from e-waste, e-waste dismantling workshop and surface soil from inside and outside of an e-waste recycling plant in Shanghai, Eastern China. The results showed that PBDEs were detected in the majority of e-waste, and the concentrations of ΣPBDEs ranged from not detected to 175 g/kg, with a mean value of 10.8 g/kg. PBDEs were found in TVs made in China after 1990. The mean concentrations of ΣPBDEs in e-waste made in Korea, Japan, Singapore and China were 1.84 g/kg, 20.5 g/kg, 0.91 g/kg, 4.48 g/kg, respectively. The levels of ΣPBDEs in e-waste made in Japan far exceed the threshold limit of RoHS (1.00 g/kg). BDE-209 dominated in e-waste, accounting for over 93%. The compositional patterns of PBDEs congeners resembled the profile of Saytex 102E, indicating the source of deca-BDE. Among the samples of dust and surface soil from a typical e-waste recycling site, the highest concentrations of Σ18PBDEs and BDE-209 were found in dust in e-waste, ranging from 1960 to 340,710 ng/g and from 910 to 320,400 ng/g, which were 1-2 orders of magnitude higher than other samples. It suggested that PBDEs released from e-waste via dust, and then transferred to surrounding environment.

Gridded field observations of polybrominated diphenyl ethers in soils of North China

Polybrominated diphenyl ethers (PBDEs) were measured in 87 soil samples collected from North China. Eleven PBDE congeners (BDE28, 47, 49, 66, 99, 100, 119, 183, 196, 203, and 209) were identified with a high frequency of detection (84-100 %) in soil samples, and their frequencies were used for statistical analysis in the present study. PBDE concentrations ranged from 0.08 to 8260 ng/g with a mean of 202 ng/g, thus indicating severe pollution at these sample sites. BDE209 was the predominant congener with concentrations of 0.08-8140 ng/g (mean 188). Analysis of the spatial distribution of PBDEs in North China soils indicated that relatively high concentrations of both lower- and higher-brominated BDEs were present in Shandong Province, and a decreasing trend in PBDE concentrations from the east toward the west of North China was observed. Source identification analysis suggested that Jinghai County in Tianjin and the coastal area of Laizhou Bay, Shandong province, were the major sources in North China. The sources in Jinghai County were connected with the dismantling of electronic waste, whereas the sources in the coastal area of Laizhou Bay were connected with the production of PBDEs. Modeling results showed that the distance between the sampling sites and these point sources had a large influence on the transfer of PBDEs.

Characterization of polybrominated diphenyl ethers (PBDEs) and hydroxylated and methoxylated PBDEs in soils and plants from an e-waste area, China

In order to characterize polybrominated diphenyl ethers (PBDEs), and hydroxylated and methoxylated PBDEs (OH-PBDEs and MeO-PBDEs) in the soil-plant system, soil and plant samples were collected from an e-waste recycling area in China. Forty one PBDEs, twelve OH-PBDEs and MeO-PBDEs were detected in the soil and plant samples. Concentrations of PBDEs in roots were significantly correlated to their concentrations in the soils, but the percentages of lower brominated congeners in the plants were higher than those in the soils. Significant positive linear relationships exist between concentrations of ∑OH-PBDEs and ∑MeO-PBDEs with higher levels of ∑MeO-PBDEs than those of ∑OH-PBDEs in the soils, plant roots and leaves. A majority of the OH-/MeO-PBDEs had the hydroxyl or methoxy group at the ortho-positions to the biphenyl bond for most of the plant species. However the occurrence of meta- and para- substituted OH-/MeO-PBDEs in soils and plants were also confirmed.

Temporal trends of PCBs, PCDD/Fs and PBDEs in soils from an E-waste dismantling area in East China

The temporal trends of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polybrominated diphenyl ethers (PBDEs) were investigated in soils from an E-waste dismantling area in East China between 2005 and 2011. Isotope dilution high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) was employed for the sample analysis. PCB levels declined as expected, while PCDD/Fs generally remained at a constant level during the sampling period, and PBDE concentrations tended to be slightly lower after 2007 although the decline was not statistically significant. The congener profiles indicated that lowly-halogenated congeners of these persistent organic pollutants (POPs) accounted for the decreasing levels and relative proportions of the POPs, suggesting that they have been gradually eliminated from the field soil over the years. However, the concentration levels of some heavy congeners (e.g., CB-209, OCDD and OCDF) showed different trends from those of the lighter ones. The general tendencies of the three types of POPs in soils were consistent with those reported in other studies in this area. The results implied that the enhanced regulations and centralized dismantling action introduced in 2005 might exert a limited influence on these three types of POPs in soils during the sampling period.

Dietary intake of PBDEs of residents at two major electronic waste recycling sites in China

The dietary intake of polybrominated diphenyl ether (PBDE) of local residents from 2 major electronic waste (e-waste) processing sites (Guiyu, Guangdong Province and Taizhou, Zhejiang Province) in China was investigated. Seventy-four food items were collected from these sites, divided into 9 food groups (freshwater fish, marine fish, shellfish, pork, poultry, chicken offal, egg, vegetables and cereals), and examined for residual PBDE concentrations. Out of all food items examined, the freshwater bighead carp (Aristichthys nobilis) contained extremely high (11,400±254 ng/g wet wt.) concentrations of PBDE, the highest concentrations amongst published data concerning PBDE detected in freshwater fish. Food consumption data obtained through semi-quantitative food intake questionnaires showed that Guiyu residents had a PBDE dietary intake of 931±772 ng/kg bw/day, of which BDE-47 (584 ng/kg bw/day) exceeded the US EPA's reference dose (100 ng/kg/day). Taizhou (44.7±26.3 ng/kg bw/day) and Lin'an (1.94±0.86 ng/kg bw/day) residents exhibited lower readings. The main dietary source of PBDEs in Guiyu and Taizhou residents was seafood (88-98%) and pork (41%) in Lin'an. The present results indicated that health risks arising from PBDE dietary exposure are of significance in terms of public health and food safety to local residents of e-waste processing sites.

Polybrominated diphenyl ethers in soils of the modern Yellow River Delta, China: occurrence, distribution and inventory

The Yellow River is the second largest river in China. In this study, the levels of polybrominated diphenyl ethers (PBDEs) in the modern Yellow River Delta (mYRD) were firstly reported. Twenty PBDE congeners in soil/sediment samples from mYRD were measured. The total PBDE concentrations ranged from non-detectable to 18257ngkg(-1) with a mean value of 836ngkg(-1). BDE-209 was the dominant congener, accounting for ∼86.1-99.5% of the total PBDEs. The congener profiles of PBDEs with higher abundances of BDE-153 and BDE-183 were similar to those in sediment of the Bohai Sea, indicating that they shared similar sources. The concentrations and congener patterns varied among different regions. Higher levels of PBDEs were found in the middle area (MA), and more complicated congener compositions were also observed in the MA, whereas lower levels of PBDEs were found in the modern course (MC) and the old course (OC). Much more PBDEs were detected in the top layer (TL) soil where more congeners were also held compared to lower soil layers, implying that more PBDEs were emitted into this area in recent years/decades. Organic matter controlled the PBDE distribution in the soil. Soil in this area might be a source of BDE209 for the Bohai Sea.

Determination of polybrominated diphenyl ethers in human semen

Some persistent organic pollutants (POPs) have been found in human semen but until this point it was unclear whether polybrominated diphenyl ethers (PBDEs) could be detected in human semen. In this study, PBDEs were found for the first time in human semen samples (n=101) from Taizhou, China. The concentrations of total PBDEs (∑PBDEs) varied from 15.8 to 86.8 pg/g ww (median=31.3 pg/g ww) and 53.2 to 121 pg/g ww (median=72.3 pg/g ww) in semen and blood samples, respectively. The ∑PBDE level in semen was about two times lower than in human blood, which was different in the distribution in the two matrices from other POPs. A correlation of ∑PBDE concentration was found between paired semen and in blood. The results suggest that semen could be used to detect PBDE burden in human body as a non-invasive matrix. In addition, the levels of BDE-209 and BDE-153, especially the latter, were much higher in blood than in semen, while the levels of BDE-28, BDE-47 and BDE-99 were comparable in the two matrices, suggesting that low brominated congeners could be more easily transferred to semen than high brominated congeners. Considering different toxicities among the PBDE congeners, it might be more significant to measure PBDEs in semen than in blood for evaluating male reproduction risks of PBDEs.

Analysis of emerging organic contaminants in environmental solid samples

Spreading sewage sludge on agricultural lands has been actively promoted by national authorities as an economic way of recycling. However, as by-product of wastewater treatment, sewage sludge may contain toxic substances, which could be incorporated into agricultural products or be distributed in the environment. Moreover, sediments can be contaminated by the discharge of wastewater effluents into rivers. This article reviews the determination of emerging contaminants (surfactants, flame retardants, pharmaceuticals and personal care products) in environmental solid samples (sludge, soil and sediment). Sample preparation, including extraction and clean-up, as well as the subsequent instrumental determination of contaminants are discussed. Recent applications of extraction techniques, such as Soxhlet extraction, ultrasound assisted extraction, pressurised liquid extraction, microwave assisted extraction and matrix solid-phase dispersion to the analysis of emerging contaminants in environmental solid samples are reviewed. Determination of these contaminants, generally carried out by gas chromatography and liquid chromatography coupled with different detectors, especially mass spectrometry for the identification and quantification of residues, is also summarised and discussed.

Comparative evaluation of environmental contamination and DNA damage induced by electronic-waste in Nigeria and China

In the last decade, China and Nigeria have been prime destinations for the world's e-waste disposal leading to serious environmental contamination. We carried out a comparative study of the level of contamination using soils and plants from e-waste dumping and processing sites in both countries. Levels of polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were analyzed using gas chromatography/spectrophotometry and heavy metals using atomic absorption spectrophotometry. DNA damage was assayed in human peripheral blood lymphocytes using an alkaline comet assay. Soils and plants were highly contaminated with toxic PAHs, PCBs, PBDEs, and heavy metals in both countries. Soil samples from China and plant samples from Nigeria were more contaminated. There was a positive correlation between the concentrations of organics and heavy metals in plant samples and the surrounding soils. In human lymphocytes, all tested samples induced significant (p<0.05) concentration-dependent increases in DNA damage compared with the negative control. These findings suggest that e-waste components/constituents can accumulate, in soil and surrounding vegetation, to toxic and genotoxic levels that could induce adverse health effects in exposed individuals.

Plant uptake of atmospheric brominated flame retardants at an E-waste site in southern China

Brominated flame retardants (BFRs) were measured in eucalyptus leaves and pine needles as well as the leaf surface particles (LSPs) of the two species at an e-waste site in southern China in 2007-2008. The monthly concentrations of total BFRs in the eucalyptus leaves and pine needles were in range of 30.6-154 and 15.1-236 ng/g dry weight, respectively, and relatively higher concentrations were observed in winter and spring. Correlation analysis of BFR concentrations and comparison of PBDE compositions between the plants and LSPs, air (gaseous and particle-bound phases), and ambient variables were conducted. The results revealed that BFRs in the plants, especially for less brominated BFRs, showed positive relationships with BFRs in the LSPs and negative relationships with the gaseous BFRs and ambient temperature. The PBDE profiles in the plants were similar to the gaseous profile for low brominated BDEs (di- through hexa-BDEs) and to the LSP profiles for highly brominated BDEs (hepta- through deca-BDEs). Applying McLachlan's framework to our data suggests that the uptake of BFRs was controlled primarily by gaseous partitioning equilibrium for compounds with log octanol-air partition coefficients (K(OA)) < 12 and by particle-bound deposition for compounds with log K(OA) > 13. Different relationships between the plant/air partition coefficient (K(PA)) and K(OA), which depend on the uptake mechanisms, were observed for polybrominated diphenyl ethers (PBDEs). This paper adds to the current knowledge of the factors and mechanisms governing plant uptake of semivolatile organic compounds with relatively high K(OA) in the environment.

Long term trends in PBDE concentrations in gannet (Morus bassanus) eggs from two UK colonies

We used the eggs of an avian sentinel, the Northern gannet (Morus bassanus), to determine long-term (1977-2007) trends in PBDE contamination in Western Atlantic (Ailsa Craig colony) and North Sea (Bass Rock colony) waters around the UK. BDEs 47, 49, 99, 100, 153, 154 were the most abundant and were found in all eggs. Individual congener and ΣPBDE concentrations in eggs from both colonies increased mainly from the late 1980s, peaked in 1994, and then rapidly declined so that concentrations in 2002 were similar to or lower than those in the 1970s and 1980s. The PBDE congener profile and temporal variation in PBDE concentrations suggests that the Penta-BDE technical formula was the main source of PBDE contamination. However, contributions of heavier BDE congeners to ΣPBDE concentrations have increased over time, suggesting other sources are becoming more important. PBDEs had no measurable effect on egg volume or eggshell index.

Polybrominated diphenyl ethers (PBDEs) in soils along a rural-urban-rural transect: sources, concentration gradients, and profiles

This study reports concentrations of PBDEs in surface soil samples collected along a 140 km transect across Kuwait to assess the role of urban centers as sources of persistent organic pollutants to the surrounding environment. The ΣPBDE concentrations varied by a factor of ~250 and ranged from 289 to 80,078 pgg (-1)d.w. The concentrations of PBDEs in Kuwait City were significantly higher (p<0.01) than those collected from sites outside the city supporting the hypothesis that urban centers are sources of PBDEs. The congener profiles were dominated by BDE-209, accounting for 93% of the PBDEs in the soil samples. The concentrations of all congeners (except BDE-209) were highly correlated with percent organic carbon (%OC) (p>0.05) when the data from Kuwait City was omitted from the analysis. These findings suggest that soil concentrations outside the urban centers were close to equilibrium with the atmosphere.

On-site and off-site atmospheric PBDEs in an electronic dismantling workshop in south China: gas-particle partitioning and human exposure assessment

Gas samples and total suspended particle during work and off work time were investigated on-site and off-site electronic waste dismantling workshop (I- and O-EWDW), then compared with plastic recycling workshop (PRW) and waste incineration plant (WIP). TSP concentrations and total PBDE were 0.36-2.21 mg/m(3) and 27-2975 ng/m(3) at different workshops, respectively. BDE-47, -99, and -209 were major ∑PBDE congeners at I-EWDW and WIP, while BDE-209 was only dominant congener in PRW and control sites during work time and all sites during off work time. The gas-particle partitioning result was well correlated with the subcooled liquid vapor pressure for all samples, except for WIP and I-EDWD, at park during work time, and residential area during off work time. The predicted urban curve fitted well with measured φ values at O-DEWD during work time, whereas it was slightly overestimated or underestimated for others. Exposure assessment revealed the highest exposure site was I-EDWD.

The cytotoxic effects of synthetic 6-hydroxylated and 6-methoxylated polybrominated diphenyl ether 47 (BDE47)

Polybrominated diphenyl ethers (PBDE) have been widely applied as flame retardants in plastics, polyurethane foam, paints, and synthetic fabrics. The rising PBDE level in human tissues and environment has led to concern about the health impact of exposure to PBDE. The 2,2',4,4'-tetrabromodiphenyl ether (BDE47), the dominant PBDE congener found in the environment and human tissues, has been shown to be an endocrine disruptor. It has also been reported to cause liver and neurodevelopmental toxicity. BDE47 can be metabolized to 6-OH-BDE47 and 6-MeO-BDE47. So far little has been reported on the cytotoxicity of the metabolites. In the present study, the cytotoxicity of the two metabolites was investigated by exposing human hepatoma cell line HepG2 to different doses of 6-OH-BDE47 and 6-MeO-BDE47. The cell viability, cell cycle, apoptosis, DNA damage, micronucleus levels, and oxidative stress response were studied. The results indicated that both metabolites could markedly inhibit the proliferation of HepG2 cells with 6-OH-BDE47 showing a stronger effect, and significantly increase the micronucleus level and apoptosis rate in a dose-dependant manner. Moreover, treatment with 6-OH-BDE47 (≥0.5 μM) resulted in a marked cell cycle block. The SCGE experiments revealed that both metabolites could cause DNA damage in a dose-dependant manner. Analysis of the oxidative stress response showed that 6-OH-BDE47 treatment (≥2.0 μM) significantly increased intracellular ROS levels as indicated by GSH depletion and elevation of SOD level, whereas 6-MeO-BDE47 showed a weaker effect, suggesting that oxidative stress might play a role in the cytotoxic effects. We concluded that 6-OH-BDE47 or 6-MeO-BDE47 exposure was able to induce inhibition of cell viability, increase of apoptosis rate, cell cycle block, and DNA damages, which might involve the alterated oxidative stress response due to the elevated free radicals and impaired antioxidative system.

Source identification and health risk of polycyclic aromatic hydrocarbons associated with electronic dismantling in Guiyu town, South China

In this study the concentrations and distribution of sixteen polycyclic aromatic hydrocarbons (PAHs) were investigated in gas and total suspended particle (TSP) samples collected during daytime and night time. The sampling locations included an electronic waste dismantling workshop (EW), a plastic recycling workshop (PW) and a waste incineration field (WF) in Guiyu, China. A large residential area (RA) in this region was used as a control site. In the daytime, the highest concentration was found at WF (1041 ng m(-3)); while in the night time the highest concentration was found outside of EW (744 ng m(-3)). Comparison between work hours (daytime) and rest hours (night time) displayed that the total PAHs (gas+particulate phase) concentrations and the percentages of PAHs associated with TSP were higher at night than those in the daytime in all sampling workshops except WF. Source diagnostic-ratio analysis revealed that unwanted materials and smoldering honeycomb coals were the main sources of PAHs in EW, WF and PW. Benzo[a]pyrene equivalent [BaPeq] concentrations calculated by using the toxic equivalent factors [TEFs] suggested that the occupational exposure levels were not significantly high when compared with other occupational exposure. Additionally, our study suggested that the smoldering of unwanted materials could produce much more toxic PAHs compounds.

Bioaccumulation, maternal transfer and elimination of polybrominated diphenyl ethers in wild frogs

To investigate bioaccumulation, maternal transfer and elimination of polybrominated diphenyl ethers (PBDEs) in amphibians, we collected adult frogs (Rana limnocharis) from a rice field in an e-waste recycling site in China. We found that ∑PBDEs in the whole frogs and various tissues (brain, liver, testis and egg) ranged from 17.10 to 141.11 ng g(-1) wet weight. Various tissues exhibited a similar PBDE congener profile, which was characterized by intermediate brominated congeners (BDE-99 and BDE-153) as the largest contributors, with less lower brominated congeners (BDE-28 and BDE-47) and higher brominated congeners (BDE-209). The maternal transfer capacity of PBDEs declined with the increase in bromine numbers of PBDE congeners. We suggest that the bromine atom number (the molecular size, to some degree) might be a determining factor for the maternal transport of a PBDE congener rather than K(ow) (Octanol-Water partition coefficient), which expresses a compound's lipophilicity. ∑PBDEs concentrations in frogs decreased over time during a depuration period of 54 days when these wild frogs were brought to the lab from the e-waste recycling site. The half-life of ∑PBDEs was 35 days, with about 14 days for BDE-47, and 36 and 81 days for BDE-99 and BDE-153, respectively. The data shows that the elimination of PBDEs has no essential difference from aquatic and terrestrial species.

Major pollutants in soils of abandoned agricultural land contaminated by e-waste activities in Hong Kong

Polycyclic aromatic hydrocarbon (PAH), polychlorinated biphenyl (PCB), polybrominated diphenyl ether (PBDE) compounds and five heavy metals (cadmium, copper, chromium, lead, and zinc) were determined in soil samples collected from six sites of abandoned agricultural land affected by electronic-waste: e-waste dismantling workshop [EW (DW)], e-waste open burning site [EW (OBS)], e-waste storage [EW (S)], and agricultural (A) in the New Territories, Hong Kong. Persistent organic pollutants (POPs) and heavy metals were detected in all soil samples. EW (DW) contained the highest concentrations of PAHs, Cr, Cu, and Zn, whereas EW (OBS) had the highest concentrations of PCBs, PBDEs, Cd, and Pb. PAH at EW (DW) and EW (OBS) and PCB concentrations at EW (OBS) exceeded the target values of the New Dutch list, whereas Cd, Cu, Cr, Pb, and Zn levels exceeded the Chinese legislation for the protection of agricultural production and safeguarding of human health, by 3-11 times at EW (OBS) and 5-8 times at EW (DW). Lead at EW (OBS) and EW (DW) and Cr at EW (DW) greatly exceeded the Canadian Soil Quality Guidelines by 46 and 20 times and 27 times, respectively. Concentrations of POPs and heavy metals at EW (DW) and EW (OBS) were significantly higher than at EW (S) and A. It was concluded that e-waste activities led to increases of toxic chemicals at these abandoned agricultural land, which would hinder the redevelopment of the land.

Occurrence, distribution, and source of polybrominated diphenyl ethers in soil and leaves from Shenzhen Special Economic Zone, China

Polybrominated diphenyl ethers (PBDEs) were measured in soil and three plant species samples taken at different land use areas in Shenzhen China. The concentrations of Σ(7)BDEs (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183) and BDE-209 in the surface soils ranged from 0.23 to 271 and 8.9 to 5,956 ng/g dry weight (dw), respectively. These figures are comparable to that in the soils of electronic waste dismantling sites. BDE-209 was the predominant congener (contributes 85-99% of Σ(8)PBDEs (Σ(7)PBDEs plus BDE-209)) in soils. The regression slopes of total organic carbon and individual BDE congeners were rather gentle, indicating that factors other than soil organic matter regulated the soil concentrations. Proximity to sources of deposition processes might be the major factors. In the plant leaves, Σ(7)BDEs and BDE-209 concentrations ranged from 1.29 to 5.91 and 5.49 to 28.2 ng/g dw, respectively. BDE-209 is also the dominant component, but the contribution was much lower compared with that in soils. Bauhinia purpurea Linn. and Michelia alba DC. show some similarities on the uptake of PBDEs, while Ficus microcarpa var. pusillifolia is different from them. The correlations between plant leaf concentrations and predicted gaseous concentrations were moderate, indicating that gaseous concentration did not influence the leaf concentration significantly.

Elevated concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans and polybrominated diphenyl ethers in hair from workers at an electronic waste recycling facility in eastern China

Hair samples collected from e-waste recycling workers (n=23 males, n=4 females) were analyzed to assess occupational exposures to polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) at a large e-waste recycling facility in Taizhou, eastern China. Hair samples from a reference population composed of residents of Shanghai (n=11) were analyzed for comparison. The mean concentration of ∑PBDEs (range, 22.8-1020 ng/g dw; mean, 157 ng/g dw) found in hair samples from e-waste recycling workers was approximately 3 times higher than the mean determined for the reference samples. The congener profiles of PBDEs in hair from e-waste recycling workers were dominated by BDE 209, whereas the profiles in the reference-population samples showed comparable levels of BDE 47 and BDE 209. Total PCDD/F concentrations in hair from e-waste workers (range, 126-5820 pg/g dw; mean, 1670 pg/g dw) were approximately 18-fold greater than the concentrations measured in hair from the reference population. Concentrations of PCDFs were greater than concentrations of PCDDs, in all of the hair samples analyzed (samples from e-waste and non-e-waste sites). Tetrachlorodibenzofurans (TCDFs) were the major homologues in hair samples. Overall, e-waste recycling workers had elevated concentrations of both PBDEs and PCDD/Fs, indicating that they are exposed to high levels of multiple persistent organic pollutants.

Polybrominated diphenyl ethers in chicken tissues and eggs from an electronic waste recycling area in southeast China

The levels and distributions of polybrominated diphenyl ethers (PBDEs) in chicken tissues from an electronic waste (e-waste) recycling area in southeast China were investigated. Human dietary intake by local residents via chicken muscle and eggs was estimated. The mean PBDEs concentrations in tissues ranged from 15.2 to 3138.1 ng/g lipid weight (lw) and in egg the concentration was 563.5 ng/g lw. The results showed that the level of total PBDEs (sigmaPBDEs) in the chicken tissue was 2-3 orders of magnitude higher than those reported in the literature. The large difference of sigmaPBDEs concentrations between tissues confirmed that the distribution of PBDEs in tissues depend on tissue-specificity rather than the "lipid-compartment". BDE-209 was the predominant congener (82.5%-94.7% of sigmaPBDEs) in all chicken tissues except in brain (34.7% of sigmaPBDEs), which indicated that deca-BDE (the major commercial PBDE formulation comprising 65%-70% of total production) was major pollution source in this area and could be bioaccumulated in terrestrial animals. The dietary PBDEs intake of the local residents from chicken muscle and egg, assuming only local bred chickens and eggs were consumed, ranged from 2.2 to 22.5 ng/(day x kg body weight (bw)) with a mean value of 13.5 ng/(day x kg bw), which was one order of magnitude higher than the value reported in previous studies for consumption of all foodstuffs.

Application of mass spectrometry in the analysis of polybrominated diphenyl ethers

This review summarized the applications of mass spectrometric techniques for the analysis of the important flame retardants polybrominated diphenyl ethers (PBDEs) to understand the environmental sources, fate and toxicity of PBDEs that were briefly discussed to give a general idea for the need of analytical methodologies. Specific performance of various mass spectrometers hyphenated with, for example, gas chromatograph, liquid chromatograph, and inductively coupled plasma (GC/MS, LC/MS, and ICP/MS, respectively) for the analysis of PBDEs was compared with an objective to present the information on the evolution of MS techniques for determining PBDEs in environmental and human samples. GC/electron capture negative ionization quadrupole MS (GC/NCI qMS), GC/high resolution MS (GC/HRMS) and GC ion trap MS (GC/ITMS) are most commonly used MS techniques for the determination of PBDEs. New analytical technologies such as fast tandem GC/MS and LC/MS become available to improve analyses of higher PBDEs. The development and application of the tandem MS techniques have helped to understand environmental fate and transformations of PBDEs of which abiotic and biotic degradation of decaBDE is thought to be one major source of Br(1-9)BDEs present in the environment in addition to direct loading from commercial mixtures. MS-based proteomics will offer an insight into the molecular mechanisms of toxicity and potential developmental and neurotoxicity of PBDEs.

Environmental and human exposure to persistent halogenated compounds derived from e-waste in China

Various classes of persistent halogenated compounds (PHCs) can be released into the environment due to improper handling and disposal of electronic waste (e-waste), which creates severe environmental problems and poses hazards to human health as well. In this review, polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), tetrabromobisphenol A (TBBPA), polybrominated phenols (PBPs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), and chlorinated polycyclic aromatic hydrocarbons (ClPAHs) are the main target contaminants for examination. As the world's largest importer and recycler of e-waste, China has been under tremendous pressure to deal with this huge e-waste situation. This review assesses the magnitude of the e-waste problems in China based on data obtained from the last several years, during which many significant investigations have been conducted. Comparative analyses of the concentrations of several classes of toxic compounds, in which e-waste recycling sites are compared with reference sites in China, have indicated that improper e-waste handling affects the environment of dismantling sites more than that of control sites. An assessment of the annual mass loadings of PBDEs, PBBs, TBBPA, PBPs, PCDD/Fs, and ClPAHs from e-waste in China has shown that PBDEs are the dominant components of PHCs in e-waste, followed by ClPAHs and PCDD/Fs. The annual loadings of PBDEs, ClPAHs, and PCDD/Fs emission were estimated to range from 76,200 to 182,000, 900 to 2,000 and 3 to 8 kg/year, respectively. However, PCDD/Fs and ClPAHs should not be neglected because they are also primarily released from e-waste recycling processes. Overall, the magnitude of human exposure to these toxics in e-waste sites in China is at the high end of the global range.

Dual body burdens of polychlorinated biphenyls and polybrominated diphenyl ethers among local residents in an e-waste recycling region in Southeast China

E-waste recycling resulted in serious pollution of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Taizhou of Zhejiang Province, China. The aims of this study were to assess dual body burdens of the two pollutants and potential health risk for local residents. Blood samples were collected from two e-waste recycling sites, Luqiao (where PCBs-containing e-wastes were recycled) and Wenling (where PBDEs-containing e-wastes were recycled). The mean summation SigmaPCBs (CB-105, 118, 153, 183, and 180) and summation SigmaPBDEs (BDE-28, 47, 99, 100, 153, 154, 180, and 209) were 204.20 and 117.58 ng g(-1) lipid in the blood from Luqiao, respectively, while they were 83.80 and 357.44 ng g(-1) lipid from Wenling, respectively. The PCBs levels among Luqiao residents were comparable to the values reported for US populations, while the PBDEs levels among two study populations were higher than the values from US populations. This is the first report to present dual body burdens of PCBs and PBDEs at so high levels. Based on previous epidemiologic data, it is suggested that dual burdens of PCBs and PBDEs at so high levels might pose health risk for local residents. In addition, no correlation between PCBs or PBDEs concentrations and the ages of the volunteers was observed in the two populations, which was explained by similar exposure time. No correlation of PBDEs with PCBs concentrations suggested different pathways of human exposures to PCBs and PBDEs. Our findings have raised concern about human health risk of dual exposure to PCBs and PBDEs resulting from e-waste recycling.

E-waste: an assessment of global production and environmental impacts

E-waste comprises discarded electronic appliances, of which computers and mobile telephones are disproportionately abundant because of their short lifespan. The current global production of E-waste is estimated to be 20-25 million tonnes per year, with most E-waste being produced in Europe, the United States and Australasia. China, Eastern Europe and Latin America will become major E-waste producers in the next ten years. Miniaturisation and the development of more efficient cloud computing networks, where computing services are delivered over the internet from remote locations, may offset the increase in E-waste production from global economic growth and the development of pervasive new technologies. E-waste contains valuable metals (Cu, platinum group) as well as potential environmental contaminants, especially Pb, Sb, Hg, Cd, Ni, polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs). Burning E-waste may generate dioxins, furans, polycyclic aromatic hydrocarbons (PAHs), polyhalogenated aromatic hydrocarbons (PHAHs), and hydrogen chloride. The chemical composition of E-waste changes with the development of new technologies and pressure from environmental organisations on electronics companies to find alternatives to environmentally damaging materials. Most E-waste is disposed in landfills. Effective reprocessing technology, which recovers the valuable materials with minimal environmental impact, is expensive. Consequently, although illegal under the Basel Convention, rich countries export an unknown quantity of E-waste to poor countries, where recycling techniques include burning and dissolution in strong acids with few measures to protect human health and the environment. Such reprocessing initially results in extreme localised contamination followed by migration of the contaminants into receiving waters and food chains. E-waste workers suffer negative health effects through skin contact and inhalation, while the wider community are exposed to the contaminants through smoke, dust, drinking water and food. There is evidence that E-waste associated contaminants may be present in some agricultural or manufactured products for export.

Polybrominated diphenyl ethers in the atmosphere of Taizhou, a major e-waste dismantling area in China

Concentrations, congener profiles, gas-particle partitioning and size distributions of polybrominated diphenyl ethers (PBDEs) in the atmosphere of Taizhou were studied to evaluate the impact of e-waste recycling on the environment. Total concentration of 13 PBDEs near the e-waste dismantling area was 506 pg m(-3) in summer and 1,662 pg m(-3) in winter, about 7 times higher than that of the reference urban site, but much lower than that of Guiyu, another major e-waste dismantling area in China. This should be attributable to the centralized management measures taken in recent years in Taizhou. BDE-209 was the major congener and mainly in coarse particles.

Diffusion of polybrominated diphenyl ether (PBDE) from an e-waste recycling area to the surrounding regions in Southeast China

Using Cinnamomum camphora (C. camphora) leaves as biomonitors, we investigated that the diffusion of polybrominated diphenyl ethers (PBDEs) from an e-waste recycling area to the surrounding regions. Variance in sigma(32)PBDEs concentrations (0.46-399.93 ng g(-1) dry weight) in the leaves showed that PBDEs from the e-waste recycling area diffused into the surrounding regions, and resulted in a halo of PBDEs contamination, at least 74 km in radius. The attenuation of sigma(32)PBDEs in the diffusing process fitted in log-linear regression. The difference in the attenuating slopes of linear equations among different directions can be explained by terrain and wind direction. The attenuation of PBDE congeners also fitted well in log-linear regression. The findings that similar attenuating slopes and characteristic travel distance among congeners suggest that the transport behavior of lower brominated congeners might not differ from that of higher brominated congeners in short-range scale.

Ecotoxicological effects of mixed pollutants resulted from e-wastes recycling and bioaccumulation of polybrominated diphenyl ethers in Chinese loach (Misgurnus anguillicaudatus)

To understand potential ecotoxicological effects of electrical and electronic equipment waste (e-waste) recycling and polybrominated diphenyl ethers (PBDEs) bioaccumulation in loaches, a semi-field experiment using Chinese loach (Misgurnus anguillicaudatus) as experimental fish was performed. Larval loaches were kept in net-cage for three months in an e-wastes recycling site and a reference site in Southeastern China. There was significant difference of the survival rate between the loaches from the e-wastes recycling site (27%, 19/70) and from reference site (70%, 49/70). Histopathological responses were also found in all the livers examined in loaches from the e-wastes recycling site. These results showed that mixed pollutants resulted from e-wastes recycling led to ecotoxicological effects on loaches. The bioaccumulation of polybrominated diphenyl ethers (PBDEs), the main pollutants in e-waste, in loaches was also studied, the mean concentration of total PBDEs in sediment was 6726.17 ng/g wet weight and in water samples was 4.08 ng/L (dissolved phase). BDE 209 was the dominant congener in sediment and with relatively high concentration in water. Relatively low concentration of BDE 209 (less than 0.01% of total PBDEs) and high concentration of BDE47 (up to 39.34% of total PBDEs) were detected in loaches.

Levels and distribution of brominated flame retardants in the soil of Harbin in China

This study reports the presence of brominated flame retardants in the topsoil in and around Harbin, a city in northeastern China. Samples of soil were collected from 17 locations in 2006, and the levels of 9 polybrominated diphenylethers (PBDEs 17, 28, 47, 66, 99, 100, 153, 154, and 183) ranged from 2.45 to 55.9 pg/g dry weight (dw) with a mean of 26.3 pg/g dw. These levels are very low comparing with those for some cities in Europe and USA. BDE 209 and hexabromocyclododecane were the two dominant congeners, with mean concentrations of 520 pg/g dw and 1750 pg/g dw, respectively. The concentrations of the total nine PBDE congeners clearly decreased from urban areas to background, but the compositions of individual congeners differed. Proportions of heavier congeners decreased while those of lighter congeners increased, along urban-rural-background transect, providing evidence for an urban fractionation effect. Correlation analysis indicated similar sources for PBDEs, hexabromocyclododecane, and 1,2-bis(2,4,6-tribromophenoxy)-ethane from urban areas but pentabromoethylbenzene was probably present due to long-range atmospheric transport. Principal component analysis was used to determine the characteristics of the relationships among these brominated flame retardants in the field.