State of polybrominated diphenyl ethers in China: an overview

Visual toxicity in zebrafish larvae following exposure to 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), triphenyl phosphate (TPhP), and isopropyl phenyl diphenyl phosphate (IPPP)

TPhP and IPPP, alternatives to PBDEs as flame retardants, have been studied for their developmental toxicity, but their visual toxicities are less understood. In this study, zebrafish larvae were exploited to evaluate the potential ocular impairments following exposure to BDE-47, TPhP, and IPPP. The results revealed a range of ocular abnormalities, including malformation, vascular issues within the eyes, and histopathological changes in the retina. Notably, the visually mediated behavioral changes were primarily observed in IPPP and TPhP, indicating that they caused more severe eye malformations and vision impairment than BDE-47. Molecular docking and MD simulations showed stronger binding affinity of TPhP and IPPP to RAR and RBP receptors. Elevated ROS and T3 levels induced by these compounds led to apoptosis in larvae eyes, and increased GABA levels induced by TPhP and IPPP hindered retinal repair. In summary, our results indicate TPhP and IPPP exhibit severer visual toxicity than BDE-47, affecting eye development and visually guided behaviors. The underlying mechanism involves disruptions in RA signaling, retinal neurotransmitters imbalance, thyroid hormones up-regulation, and apoptosis in larvae eyes. This work highlights novel insights into the need for cautious use of these flame retardants due to their potential biological hazards, thereby offering valuable guidance for their safer applications.

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

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

Polybrominated diphenyl ethers (PBDEs) in household dust: A systematic review on spatio-temporal distribution, sources, and health risk assessment

Much attention has been paid on polybrominated diphenyl ethers (PBDEs) in household dust due to their ubiquitous occurrences in the environment. Based on the data from 59 articles sampled from 2005 to 2020, we investigated the spatio-temporal distribution, sources, and health risk of 8 PBDE homologues in household dusts worldwide. BDE-209 is the predominant PBDE in household dusts, followed by BDE-99 and BDE-47. The total concentrations of PBDEs (∑₈PBDEs) are found to be high in household dusts sampled from 2005 to 2008 and show a significant decline trend from 2009 to 2016 (p < 0.05) and a little upward tendency from 2017 to 2020. The concentrations of PBDEs in household dusts vary greatly in different countries of the world. The use of penta-BDE is the main source of three to five bromo-biphenyl ether monomers contributing 17.4% of ∑₈PBDEs, while BDE-209 and BDE-183 are derived from the use of household appliances contributing 82.6% of ∑₈PBDEs. Ingestion is the main exposure route for adults and toddlers, followed by dermal contact. The values of hazard index (HI) exposed to PBDEs in household dusts are all less than 1 for both adults and toddlers, indicating a low non-cancer risk. The incremental lifetime cancer risks (ILCRs) of BDE-209 are less than 10^-6 for both adults and toddlers, suggesting a negligible risk. However, the total carcinogenic risk of toddlers is higher than that of adults, indicating that much attention should be paid to toddlers exposed to BDE-209 in household dust.

New insights into mechanism of emerging pollutant polybrominated diphenyl ether inhibiting sludge dark fermentation

Polybrominated diphenyl ethers (PBDEs), derived from electronics, furniture, etc., are detected with high level in excess sludge (ES). In this work, the influence of PBDEs on ES dark fermentation (ESDF) hydrogen production and the related key mechanisms were explored. The result shows PBDEs exposure reduced hydrogen production, and hydrogen accumulation decreased from 17.6 mL/g in blank to 12.3 mL/g with 12.0 mg/Kg PBDEs. PBDEs induced the reactive oxygen species production, which directly led to cell inactivation and reduced hydrogen production. Furthermore, PBDEs decreased ES disintegration, hydrolysis, acidification and homoacetogenic processes and inhibited the activities of enzymes related to hydrogen production. PBDEs also affected the diversity and richness of microbial communities in dark fermentation systems, especially high doses of PBDEs reduced the relative abundance of microorganisms associated with hydrogen production. In conclusion, PBDEs reduce hydrogen generation from ES.

Occurrence of persistent organic pollutants (POPs) in the atmosphere of South Korea: A review

Numerous studies found the presence of persistent organic pollutants (POPs) in various environmental compartments, including air, water, and soil. POPs have been discovered in various industrial and agricultural products with severe environmental and human health consequences. According to the data, South Korea is a hotspot for POP pollution in the southern part of Asia; hence, South Korea has implemented the Stockholm Convention's National Implementation Plan (NIP) to address this worldwide issue. The purpose of this review is to assess the distribution pattern of POPs pollution in South Korea's atmosphere. According to findings, PAHs, PCBs, BFRs, and PBDEs significantly polluted the atmosphere of South Korea; however, assessing their exposure nationwide is difficult due to a shortage of data. The POPs temporal trend and meta-analysis disclosed no proof of a decrease in PAHs and BFRs residues in the atmosphere. However, POP pollution in South Korea tends to decrease compared to contamination levels in neighboring countries like Japan and China.

Perinatal exposure to low-level PBDE-47 programs gut microbiota, host metabolism and neurobehavior in adult rats: An integrated analysis

Polybrominated diphenyl ethers (PBDEs), a major class of flame retardants, have been extensively applied in plastics, electrical equipment, textile fabrics, and so on. Early-life exposure to PBDEs is correlated to neurobehavioral deficits in adulthood, yet the underlying mechanism has not been fully understood. Increasing evidence has demonstrated that gut microbiota dysbiosis and serum metabolites alterations play a role in behavioral abnormalities. However, whether their perturbation is implicated in PBDEs-induced neurotoxicity remains unclear. Here, we sought to explore the effects of developmental exposure to environmentally relevant levels of 2, 2', 4, 4'-tetrabromodiphenyl ether (PBDE-47), a major congener in human samples, on gut microbiota and serum metabolic profile as well as their link to neurobehavioral parameters in adult rats. The open field test showed that gestational and lactational exposure to PBDE-47 caused hyperactivity and anxiety-like behavior. Moreover, 16S rRNA sequencing of fecal samples identified a distinct community composition in gut microbiota following PBDE-47 exposure, manifested as decreased genera Ruminococcaceae and Moraxella, increased families Streptococcaceae and Deferribacteraceae as well as genera Escherichia-Shigella, Pseudomonas and Peptococcus. Additionally, the metabolomics of the blood samples based on liquid chromatography-mass spectrometry revealed a significant shift after PBDE-47 treatment. Notably, these differential serum metabolites were mainly involved in amino acid, carbohydrate, nucleotide, xenobiotics, and lipid metabolisms, which were further validated by pathway analysis. Importantly, the disturbed gut microbiota and the altered serum metabolites were associated with each other and with neurobehavioral disorders, respectively. Collectively, these results suggest that gut microbiota dysbiosis and serum metabolites alterations potentially mediated early-life low-dose PBDE-47 exposure-induced neurobehavioral impairments, which provides a novel perspective on understanding the mechanisms of PBDE-47 neurotoxicity.

Understanding the mechanism of polybrominated diphenyl ethers reducing the anaerobic co-digestion efficiency of excess sludge and kitchen waste

Polybrominated diphenyl ethers (PBDEs) widely existing in the environment can pose a serious threat to the ecological safety. However, the influence of PBDEs on methane production by excess sludge (ES) and kitchen waste (KW) anaerobic co-digestion and its mechanism is not clear. To fill this gap, in this work, the co-digestion characteristics of ES and KW exposed to different levels of PBDEs at medium temperature were investigated in sequencing batch reactor, and the related mechanisms were also revealed. The results showed that PBDEs reduced methane production and the proportion of methane in the biogas. Methane yield decreased from 215.3 mL/g· volatile suspended solids (VSS) to 161.5 mL/(g·VSS), accompanied by the increase of PBDE content from 0 to 8.0 mg/Kg. Volatile fatty acid (VFA) yield was also inhibited by PBDEs; especially when PBDEs were 8.0 mg/Kg, VFA production was only 215.6 mg/g VSS, accounting for 75.7% of that in the control. Mechanism investigation revealed PBDEs significantly inhibited the processes of hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Further study showed that PBDEs could inhibit the degradation and bioavailability of ES and KW, but it had a greater inhibition on the utilization of KW. Enzyme activity investigation revealed that all the key enzyme activities related to methane production were suppressed by PBDEs.

Review of the environmental occurrence, analytical techniques, degradation and toxicity of TBBPA and its derivatives

BFRs (brominated flame retardants) are a class of compounds that are added to or applied to polymeric materials to avoid or reduce the spread of fire. Tetrabromobisphenol A (TBBPA) is one of the known BFR used many in industries today. Due to its wide application as an additive flame retardant in commodities, TBBPA has become a common indoor contaminant. Recent researches have raised concerns about the possible hazardous effect of exposure to TBBPA and its derivatives in humans and wildlife. This review gives a thorough assessment of the literature on TBBPA and its derivatives, as well as environmental levels and human exposure. Several analytical techniques/methods have been developed for sensitive and accurate analysis of TBBPA and its derivatives in different compartments. These chemicals have been detected in practically every environmental compartment globally, making them a ubiquitous pollutant. TBBPA may be subject to adsorption, biological degradation or photolysis, photolysis after being released into the environment. Treatment of TBBPA-containing waste, as well as manufacturing and usage regulations, can limit the release of these chemicals to the environment and the health hazards associated with its exposure. Several methods have been successfully employed for the treatment of TBBPA including but not limited to adsorption, ozonation, oxidation and anaerobic degradation. Previous studies have shown that TBBPA and its derivative cause a lot of toxic effects. Diet and dust ingestion and have been identified as the main routes of TBBPA exposure in the general population, according to human exposure studies. Toddlers are more vulnerable than adults to be exposed to indoor dust through inadvertent ingestion. Furthermore, TBBP-A exposure can occur during pregnancy and through breast milk. This review will go a long way in closing up the knowledge gap on the silent and over ignored deadly effects of TBBPA and its derivatives and their attendant consequences.

Characteristics of zooplankton community structure and its relationship with environmental factors in the South Yellow Sea

A total of 91 species of zooplankton were sampled from the South Yellow Sea in the summer and autumn of 2019. Copepods were the predominant arthropods. The summer sample (81) contained higher species diversity than the autumn (70). In both seasons, Calanus sinicus, Sagitta enflata, S. crassa, Doliolum denticulatum, and Macrura larva were dominant species. The average abundance of zooplankton in summer and autumn was 424.9 and 52.6 ind./m³, respectively, and the biomass was 207.7 and 107.6 mg/m³, respectively. The Shannon-Wiener index (H') in summer was higher than that in autumn, while the Pielou index (J') and Margalef index (D') were lower than those in autumn. BIOENV showed that water temperature (ST), dissolved oxygen (DO), turbidity (Tur), and tetrabromobisphenol A (TBBPA) affected the zooplankton community structure in the South Yellow Sea. The concentration of TBBPA increased from offshore to nearshore, with a significant negative impact on diversity in summer.

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.

Bioinformatic analyses of hydroxylated polybrominated diphenyl ethers toxicities on impairment of adrenocortical secretory function

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) and their metabolites have severe impact on human health, but few studies focus on their nephrotoxicity. This study was conceived to explore hub genes that may be involved in two hydroxylated polybrominated diphenyl ethers toxicities on impairment of adrenocortical secretory function.

METHODS

Gene dataset was obtained from Gene Expression Omnibus (GEO). Principal component analysis and correlation analysis were used to classify the samples. Differentially expressed genes (DEGs) were screened using the limma package in RStudio (version 4.1.0). Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Reactome enrichment analyses of DEGs were conducted. Protein-protein interaction (PPI) network was established using STRING network, and genes were filtered by Cytoscape (version 3.8.2). Finally, the hub genes were integrated by plug-in CytoHubba and RobustRankAggreg, and were preliminarily verified by the Comparative Toxicogenomics Database (CTD).

RESULTS

GSE8588 dataset was selected in this study. About 190 upregulated and 224 downregulated DEGs in 2-OH-BDE47 group, and 244 upregulated and 276 downregulated DEGs in 2-OH-BDE85 group. Functional enrichment analyses in the GO, KEGG and Reactome indicated the potential involvement of DEGs in endocrine metabolism, oxidative stress mechanisms, regulation of abnormal cell proliferation, apoptosis, DNA damage and repair. 2-OH-BDE85 is more cytotoxic in a dose-dependent manner than 2-OH-BDE47. A total of 98 hub genes were filtered, and 91 nodes and 359 edges composed the PPI network. Besides, 9 direct-acting genes were filtered for the intersection of hub genes by CTD.

CONCLUSIONS

OH-PBDEs may induce H295R adrenocortical cancer cells in the disorder of endocrine metabolism, regulation of abnormal cell proliferation, DNA damage and repair. The screened hub genes may play an important role in this dysfunction.

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

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

AhR-mediated CYP1A1 and ROS overexpression are involved in hepatotoxicity of decabromodiphenyl ether (BDE-209)

Polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants. They are constantly detected in terrestrial, ocean, and atmospheric systems, and it is of particular concern that these fat-soluble xenobiotics may have a negative impact on human health. This study aimed to evaluate the toxic effect and underlying mechanism of decabromodiphenyl ether (BDE-209) on human liver in a HepG2 cell model. The results showed that BDE-209 significantly induced HepG2 cells apoptosis, increased intracellular reactive oxygen species (ROS), disturbed [Ca ²⁺] homeostasis and mitochondrial membrane potential (MMP), and caused nuclear shrinkage and DNA double-strand breaks. BDE-209 also significantly decreased the activities of antioxidant parameters, superoxide dismutase (SOD), total antioxygenic capacity (T-AOC), glutathione (GSH), and total glutathione (T-GSH). The up-regulation of the Aryl hydrocarbon receptor (AhR)/cytochrome P4501A1 (CYP1A1) signaling pathway indicates that after long-term and high-dose exposure, BDE-209 may be a liver carcinogen. Interestingly, HepG2 cells attempt to metabolize BDE-209 through the Nrf2-mediated antioxidant pathway. These findings help elucidate the mechanisms of BDE-209-induced hepatotoxicity in humans.

Polybrominated diphenyl ethers in the environmental systems: a review

PBDEs are human-influenced chemicals utilized massively as flame retardants. They are environmentally persistent, not easily degraded, bioaccumulate in the biological tissue of organisms, and bio-magnify across the food web. They can travel over a long distance, with air and water being their possible transport media. They can be transferred to non-target organisms by inhalation, oral ingestion, breastfeeding, or dermal contact. These pollutants adsorb easily to solid matrices due to their lipophilicity and hydrophobicity; thus, sediments from rivers, lakes, estuaries, and ocean are becoming their major reservoirs aquatic environments. They have low acute toxicity, but the effects of interfering with the thyroid hormone metabolism in the endocrine system are long term. Many congeners of PBDEs are considered to pose a danger to humans and the aquatic environment. They have shown the possibility of causing many undesirable effects, together with neurologic, immunological, and reproductive disruptions and possible carcinogenicity in humans. PBDEs have been detected in small amounts in biological samples, including hair, human semen, blood, urine, and breastmilk, and environmental samples such as sediment, soil, sewage sludge, air, biota, fish, mussels, surface water, and wastewater. The congeners prevailing in environmental samples, with soil being the essential matrix, are BDE 47, 99, and 100. BDE 28, 47, 99, 100, 153, 154, and 183 are more frequently detected in human tissues, whereas in sediment and soil, BDE 100 and 183 predominate. Generally, BDE 153 and 154 appear very often across different matrices. However, BDE 209 seems not frequently determined, owing to its tendency to quickly breakdown into smaller congeners. This paper carried out an overview of PBDEs in the environmental, human, and biota niches with their characteristics, physicochemical properties, and fate in the environment, human exposure, and health effects.

Environmental Estrogens and Their Biological Effects through GPER Mediated Signal Pathways

Many environmental chemicals have been found to exert estrogenic effects in cells and experimental animals by activating nuclear receptors such as estrogen receptors and estrogen-related receptors. These compounds include bisphenols, pesticides, polybrominated diphenyl ethers (PBDEs), organophosphate flame retardants, phthalates and metalloestrogens. G protein-coupled estrogen receptor (GPER) exists widely in numerous cells/tissues of human and other vertebrates. A number of studies have demonstrated that GPER plays a vital role in mediating the estrogenic effects of environmental pollutants. Even at very low concentrations, these chemicals may activate GPER pathways, thus affect many aspects of cellular functions including proliferation, metastasis and apoptosis, resulting in cancer progression, cardiovascular disorders, and reproductive dysfunction. This review summarized the environmental occurrence and human exposure levels of these pollutants, and integrated current experimental evidence toward revealing the underlying mechanisms of pollutant-induced cellular dysfunction via GPER. The GPER mediated rapid non-genomic actions play an important role in the process leading to the adverse effects observed in experimental animals and even in human beings.

Polybrominated diphenyl ethers in soils from Tianjin, North China: distribution, health risk, and temporal trends

Available information is still insufficient for a comprehensive understanding of the global distribution of polybrominated diphenyl ethers (PBDEs) in the environment. In particular, little is known about the changing trend of their distribution in urban soils. We conducted a survey of 21 PBDEs in urban soils from Tianjin, China. The chemicals were widely present in the area and summed concentrations ranged from 0.65 to 108 ng/g in soil, indicating low to moderate levels of pollution relative to other areas. BDE-209 was the predominant congener, contributing 88.9% of the concentrations of total soil PBDEs. Source assessment indicated that soil PBDEs in the area were mainly derived from the release of commercial deca-BDE from local industrial production processes and consumer products. We found that the soil concentrations of PBDEs appear to have declined in recent years, compared with other previous reports in this region. However, more studies are needed on this possible change trend of PBDE pollution, especially its impact on human health, although their calculated non-carcinogenic health risks in this study were low.

Nephrotoxicity and possible mechanisms of decabrominated diphenyl ethers (BDE-209) exposure to kidney in broilers

The flame retardant decabrominated diphenyl ether (BDE-209) is a widely used chemical in a variety of products and exists extensively in the environment. BDE-209 has been reported to induce kidney injury and dysfunction. However, the causes and mechanisms of its nephrotoxicity are still under investigation. In this study, 150 male broilers were exposed to BDE-209 concentrations of 0, 0.004, 0.04, 0.4, 4.0 g/kg for 42 days. The relative kidney weight, histopathology, markers of renal injury, oxidative stress, inflammation, apoptosis and the expression of MAPK signaling pathways-related proteins were assessed. The results showed that the concentrations of blood urea nitrogen (BUN), creatinine (CRE) and the neutrophil gelatinase-associated lipocalin (NGAL), significantly increased after exposure to BDE-209 with the doses more than 0.04 g/kg. Similarly, severe damage of renal morphology was observed, including atrophy and necrosis of glomeruli, and swelling and granular degeneration of the renal tubular epithelium. In the renal homogenates, the oxidative stress was evidenced by the elevated concentrations of MDA and NO, and decreased levels of GSH-Px, GSH and SOD. Due to the inflammatory response, the level of NF-κB and the pro-inflammatory cytokines TNF-α, IL-1β, IL-18 were remarkably upregulated, while the content of the anti-inflammatory cytokine IL-10 decreased. Additionally, the apoptotic analysis showed notable upregulations of Bax/Bcl-2 ratio, the relative expression of p-ERK1/2 and p-JNK1/2, and the expression of Bax, cytochrome c and caspase 3. The present study indicates that BDE-209 exposure can cause nephrotoxicity in broilers through oxidative stress and inflammation, which activate the phosphorylation of key proteins of the MAPK signaling pathways, and subsequently induce mitochondria-mediated kidney apoptosis.

Concentration profile, spatial distributions and temporal trends of polybrominated diphenyl ethers in sediments across China: Implications for risk assessment

Polybrominated diphenyl ethers (PBDEs) in sediments of China have been extensively investigated; however, most studies conducted to date have focused on specific locations, and the pollution and risk posed by these chemicals in sediments at the national scale remain unknown. Therefore, we analyzed the concentrations and risks of PBDEs in sediments in China and their spatiotemporal variations based on available literature. Overall, the sediments across China contain moderate to high levels of PBDEs, with BDE-209 being the dominant congener, followed by BDE-47 and BDE-99. The sediment concentrations of PBDEs were highest in southern China and lowest in northeastern China. Additionally, based on their PBDE concentrations, 18.4%, 30.0%, and 11.9% of sediment samples from rivers, lakes, and coastal waters, respectively, posed low to moderate eco-toxicological risks, but 6.90% of river sediments posed high risks. Between 2001 and 2017, the concentrations and risks of PBDEs in the sediments from rivers and coastal waters tended to decrease gradually. Additionally, there were low to moderate risks from PBDEs in lake sediments, and the risks in 2012-2017 were 3.30 times higher than those in 2006-2011. However, more studies about the spatial and temporal trends in PBDEs in sediment across China and their impacts on aquatic organisms are needed because there is still a general lack of relevant information.

Umbilical cord serum PBDE concentrations and child adiposity measures at 7 years

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) exist extensively in the environment. Toxicological studies suggested PBDEs may interfere with adipogenic pathways. However, few human evidence addressed PBDE exposures in utero related to childhood adiposity.

OBJECTIVE

We assessed associations between PBDEs concentrations in cord serum and childhood adiposity measures at 7 years.

METHODS

Among 318 mother-child pairs from Sheyang Mini Birth Cohort Study (SMBCS) in China, nine PBDE congener concentrations were quantified in umbilical cord serum using gas chromatography-negative chemical ionization mass spectrometry (GC-NCI-MS). Anthropometric indicators of children aged 7 years were measured, including weight, height and waist circumference. Age and sex-specific body mass index (BMI) z scores were calculated based on World Health Organization (WHO)'s child growth standards. Multivariate linear and logistic regression models adjusted for putative confounders were performed to examine associations between PBDE congeners and adiposity parameters.

RESULTS

BDE-209 was the most abundant congener of PBDEs with a median value of 19.5 ng/g lipid. The geometric mean values of nine PBDE congeners ranged from below limit of detection (LOD) to 18.1 ng/g lipid, and the detection rates were 46.5%~96.5%. Cord serum BDE-153 and BDE-154 concentrations were associated with lower childhood BMI z score (regression coefficient, β=-0.15, 95% confidence interval: -0.29, -0.02; p=0.02; β=-0.23, 95%CI: -0.43, -0.03; p=0.03, respectively) and lower waist circumference (β=-0.75 cm, 95%CI: -1.43, -0.06; p=0.03; β=-1.22 cm, 95%CI: -2.23, -0.21; p=0.02, respectively), after controlling for potential confounders. Moreover, prenatal BDE-154 exposure was related to a decreased obesity risk of children aged 7 years (odds ratio, OR=0.46, 95%CI: 0.22, 0.94; p=0.03). These effects were only observed among boys in sex-straitified analyses.

CONCLUSIONS

Cord serum BDE-153 and BDE-154 concentrations were related to reduced adiposity measures at 7 years of age. Further evidence regarding the impacts of prenatal PBDE exposures on childhood development is warranted.

Facile synthesis of tubular magnetic fluorinated covalent organic frameworks for efficient enrichment of ultratrace polybrominated diphenyl ethers from environmental samples

Polybrominated diphenyl ethers (PBDEs), known as the most widely used brominated flame retardant, have received great public concern due to its hidden environment and health problems. Development of highly selective and sensitive analytical approaches for enrichment and detection of ultratrace PBDEs are in high demand. Conventional sample pretreatment techniques usually require tedious procedures, long time, and excessive consumption of solvent and sample, thus hindering ultrasensitive detection of PBDEs. To address this issue, we first reported a simple room-temperature approach for synthesis of tubular magnetic fluorinated covalent organic frameworks (MCNT@TAPB-TFTA). The introduction of fluorine atoms played multiple roles in improving the frameworks' hydrophobicity and the adsorption capabilities for PBDEs. Combined with atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS), several crucial parameters of magnetic solid-phase extraction (MSPE) including adsorbent dosage, adsorption time, pH, ion strength, the eluent, elution time and elution frequencies were examined in detail. The optimal method exhibited wide linear ranges (0.01-500 ng/L), low limit of detections (LODs, 0.0045-0.018 ng/L), good correlation coefficients (r ≥ 0.9977), and high enrichment factors (EFs, 1425-1886 folds) for eight PBDEs. Furthermore, this proposed method could be successfully applied to sensitive determination of ultratrace PBDEs in environmental samples, demonstrating the promising potential of the MCNT@TPAB-TFTA as an adsorbent in sample pretreatment.

How persistent are POPs in remote areas? A case study of DDT degradation in the Qinghai-Tibet Plateau, China

Persistent organic pollutants (POPs) can undergo long-range atmospheric transport (LRAT) and deposit in remote areas. How persistent are POPs in remote areas? To answer this question, we measured two parent-DDTs and eight metabolites in soil and air along a transect in the Qinghai-Tibet Plateau, China, to quantitatively evaluate the degree of degradation of DDTs. DDTs were ubiquitous in soil and air with the total DDT concentrations (Σ₁₀DDTs) ranging 37.7-70,100 pg g^-1 dw and 3.4-175 pg m^-3, respectively. The air-soil equilibrium status indicated that the forest/basin soil was a source for most DDTs, while the plateau soil was a sink receiving DDTs from the LRAT and photodegradation in the air (for metabolites). The metabolites accounted for avg. 64.1% of Σ₁₀DDTs in soil, with avg. 93.2% from local degradation, implying the overall high degradation of DDTs. With the significant degradation, the continuous input via LRAT was deemed to be the main reason for the stable level (persistence) of POPs in the Qinghai-Tibet Plateau. Therefore, we emphasize the importance of source control for the risk management of POPs. POPs in the environment might decline rapidly due to a reduction in source input and significant degradation as indicated by our study.

Enhanced solubilization and reductive degradation of 2,2',4,4'- tretrabromodiphenyl ether by PAC-Pd/Fe nanoparticles in the presence of surfactant

2,2',4,4'-Tretrabromodiphenyl ether (BDE47) is known as a typical polybrominated diphenyl ethers (PBDEs) due to its high environmental abundance, ecological toxicity, and bioaccumulation. In this study, the influences of three typical surfactants (CTAB, SDS, and TX-100) on BDE47 solubilization and degradation by the polyanionic cellulose-stabilized Pd/Fe (PAC-Pd/Fe) nanoparticles were investigated. The results showed that BDE47 solubilities increased linearly when surfactant concentrations were above their critical micelle concentrations (CMCs), and the solubilization capacities of surfactants for BDE47 followed the order of TX-100 > CTAB > SDS. The appropriate dosages of surfactants were favorable for BDE47 degradation due to enhancing solubilization and accelerating mass transfer, while excessive surfactants inhibited BDE47 degradation due to excessive and thicker micelles formed, but still higher than no surfactant. The influences of various factors (PAC-Pd/Fe nanoparticle dosage, solution pH, and temperature) on BDE47 degradation in TX-100 solution were also tested. The results showed that BDE47 degradation followed the pseudo first-order kinetics model. The degradation rates of BDE47 increased as PAC-Pd/Fe nanoparticle dosage and temperature increased. Weak acidic condition (pH 5.5) was favorable for BDE47 degradation with 96.8% BDE47 was removed within 7.5 min, while alkaline condition (9.0) was not conducive to the degradation of BDE47. The degradation of BDE47 by PAC-Pd/Fe nanoparticles was a catalytic reductive debromination process via active H-species attack, wherein the sequential debromination was the dominant reaction. This study suggests that in the presence of moderate surfactant, PAC-Pd/Fe nanoparticles may be potentially employed to eliminate BDE47 in contaminated water.

Construction of Immunomagnetic Particles with High Stability in Stringent Conditions by Site-Directed Immobilization of Multivalent Nanobodies onto Bacterial Magnetic Particles for the Environmental Detection of Tetrabromobisphenol-A

Bacterial magnetic particles (BMPs) are an attractive carrier material for immunoassays because of their nanoscale size, dispersal ability, and membrane-bound structure. Antitetrabromobisphenol-A (TBBPA) nanobodies (Nbs) in the form of monovalence (Nb1), bivalence (Nb2), and trivalence (Nb3) were biotinylated and immobilized onto streptavidin (SA)-derivatized BMPs to construct the complexes of BMP-SA-Biotin-Nb1, -Nb2, and -Nb3, respectively. An increasing order of binding capability of BMP-SA-Biotin-Nb1, -Nb2, and -Nb3 to TBBPA was observed. These complexes showed high resilience to temperature (90 °C), methanol (100%), high pH (12), and strong ionic strength (1.37 M NaCl). A BMP-SA-Biotin-Nb3-based enzyme linked immunosorbent assay (ELISA) for TBBPA dissolved in methanol was developed, showing a half-maximum inhibition concentration (IC₅₀) of 0.42 ng mL^-1. TBBPA residues in landfill leachate, sewage, and sludge samples determined by this assay were in a range of <LOD-1.17 ng mL^-1, <LOD-0.75 ng mL^-1, and <LOD-3.65 ng g^-1 (dw), respectively, correlating well with the results by liquid chromatography tandem mass spectrometry. The BMP-SA-Biotin-Nb3 was reusable at least three times without significant loss of the binding capability. The BMP-SA-Biotin-Nb3-based ELISA, with a total assay time of less than 30 min, is promising for the rapid monitoring of TBBPA in the environment.

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.

Occurrence, gas-particle partitioning, and sources of polybrominated diphenyl ethers in the atmosphere over the Yangtze River Estuary, East China Sea

To investigate the occurrence, gas-particle partitioning, and potential sources of polybrominated diphenyl ethers (PBDEs) in the atmosphere over the Yangtze River Estuary, gas and particle samples were collected at the remote Huaniao Island, East China Sea, during a whole year from 2013 to 2014. Nine PBDEs, with total atmospheric concentration of Σ₉BDEs of 20.3 ± 26.5 pg/m³, were found in both the gas and particle phases in most samples. BDE-209 dominated both the gas and particle phases, which is consistent with the PBDE usage record in China. Seasonal variation of particle-phase Σ₉BDEs was observed, with the highest concentration in winter and the lowest in summer; however, a reversed seasonal trend was observed in the gas phase. Correlation analysis between log K_p and log K_OA suggested that the gas-particle (G/P) partitioning was in a non-equilibrium state, particularly for BDE-209 throughout the year. The K_OA-based adsorption model prediction performed relatively well for the particle-phase fraction of Br_<10-BDEs, but largely overestimated BDE-209. A steady-state model could be superior to predict G/P partitioning of BDE-209 based on annual values, though with the exception of summer samples. A relatively higher gas-phase distribution for BDE-209 than high-brominated BDEs was observed, especially in summer, when it reached 73%, implying a sustained input of gas-phase BDE-209. The potential source contribution function showed that the possible source regions for BDE-209 included Shandong and Jiangsu Provinces (the main BDE-209 production regions in China), the Yangtze River Delta region, and the southeastern coastal areas (which hosts intensive electronic waste recycling activities).

Effects of soil properties, heavy metals, and PBDEs on microbial community of e-waste contaminated soil

Heavy metals and polybrominated diphenyl ethers (PBDEs) are ubiquitous pollutants at electronic waste (e-waste) contaminated sites, their individual impacts on soil microbial community has attracted wide attention, however, limited research is available on the combined effects of heavy metals and PBDEs on microbial community of e-waste contaminated. Therefore, combined effects of heavy metals and PBDEs on the microbial community in the e-waste contaminated soil were investigated in this study. Samples were collected from Ziya e-waste recycling area in Tianjin, northern China, and the soil microbial communities were then analyzed by the high-throughput MiSeq 16S rRNA sequencing to assess the effects of soil properties, heavy metals, and PBDEs on the soil microbial community. Candidatus Nitrososphaera, Steroidobacter and Kaistobacter were the dominant microbial species in the soils. Similar microbial metabolic functions, including amino acid metabolism, carbohydrate metabolism and membrane transport, were found in all soil samples. Redundancy analysis and variation partition analysis revealed that the microbial community was mainly influenced by PBDEs (including BDE 183, BDE 99, BDE 100 and BDE 154) in horizontal soil samples. However, TN, biomass, BDE 100, BDE 99 and BDE 66 were the major drivers shaping the microbial community in vertical soil samples.

Long-term Persistent Organic Pollutants Exposure Induced Telomere Dysfunction and Senescence-Associated Secretary Phenotype

Environmentally persistent organic pollutant (POP) is the general term for refractory organic compounds that show long-range atmospheric transport, environmental persistence, and bioaccumulation. It has been reported that the accumulation of POPs could lead to cellular DNA damage and adverse effects of on metabolic health. To better understand the mechanism of the health risks associated with POPs, we conducted an evidence-based cohort investigation (n = 5,955) at the Jinghai e-waste disposal center in China from 2009 to 2016, where people endure serious POP exposure. And high levels of aging-related diseases, including hypertension, diabetes, autoimmune diseases, and reproductive disorders were identified associated with the POP exposure. In the subsequent molecular level study, an increased telomere dysfunction including telomere multiple telomere signals, telomere signal-free ends, telomere shortening and activation of alternative lengthening of telomeres were observed, which might result from the hypomethylated DNA modification induced telomeric repeat-containing RNA overexpression. Moreover, dysfunctional telomere-leaded senescence-associated secretory phenotype was confirmed, as the proinflammatory cytokines and immunosenescence hallmarks including interleukin-6, P16^INK4a, and P14^ARF were stimulated. Thus, we proposed that the dysfunctional telomere and elevated systemic chronic inflammation contribute to the aging-associated diseases, which were highly developed among the POP exposure individuals.

Halogenated organic pollutants in sediments and organisms from mangrove wetlands of the Jiulong River Estuary, South China

Eighteen sediments and four biota species were collected from mangrove wetlands of the Jiulong River Estuary (JRE) in South China to investigate the distribution of dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), dechlorane plus (DP) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE). Concentrations of ΣDDTs, ΣPCBs, ΣPBDEs, DBDPE, DP, and BTBPE in mangrove sediments ranged from 21 to 84, 0.52-2.5, 9.0-66, 5.1-32, 0.05-0.14, and 0.03-0.25 ng/g dry weight, respectively. Levels of ΣDDTs, ΣPCBs, ΣPBDEs, DBDPE and DP in mangrove biota ranged from 950 to 30000, 56-400, 8.0-35, nd-20 and 0.44-3.1 ng/g lipid weight, respectively. DDTs were the predominant halogenated organic pollutants (HOPs) in mangrove sediments from the JRE, while PBDEs were the major HOPs in mangrove sediments from the Pearl River Estuary (PRE), suggesting that sediments in JRE and PRE had different sources of HOPs. The dominance of DDTs was found in both mangrove sediments and biota from the JRE, indicating that HOPs in JRE environment mainly come from agricultural sources. The biota-sediment accumulation factors for DDTs and PCBs were significantly higher than those of PBDEs, DBDPE and DP, suggesting high bioavailability of DDTs and PCBs in mangrove biota. Trophic magnification factors for DDTs, PCBs, PBDEs, and DP were 10.5, 3.00, 2.66 and 1.23, respectively, indicating their potential of biomagnification in mangrove food webs.

Levels, distributions, and ecological risk assessments of polybrominated diphenyl ethers and alternative flame retardants in river sediments from Vaal River, South Africa

Sediments are known to be the ultimate sink for most pollutants in the aquatic environment. In this study, the concentrations of both legacy polybrominated diphenyl ethers (PBDEs) and alternative halogenated flame retardants (AHFRs) were measured in sediments samples from the Vaal River catchment. The concentrations of Σ₇BDE-congeners ranged from 20 to 78 ng g^-1 dry weight (dw) with BDE-209, -99, and -153 as the dominant congeners. The concentrations observed ranged from 9.4-56, 4-32, and 1-10.6 ng g^-1 for BDE-209, -99, and -153, respectively. The concentrations of AHFRs, mainly contributed by decabromodiphenyl ethane (DBDPE) at approximately 95% of total AHFRs, ranged from 64 to 359 ng g^-1 dw while the concentration of polybrominated biphenyls (PBBs), mainly PBB-209, ranged from 3.3-7.1 ng g^-1 dw. The ratios of AHFRs to PBDEs observed in this study were 0.76, 1.17, and 7.3 for 2-ethyl-1-hexyl-2,3,4,5-tetrabromobenzoate and bis-(2-ethylhexyl)-tetrabromophthalate (EH-TBB & BEH-TEBP)/penta-BDE; 1,2-bis-(2,4,6-tribromophenoxy) ethane (BTBPE)/octa-BDE; and DBDPE/BDE209, respectively. These results indicate dominance of some AHFRs compared to PBDEs. Our results indicates that BDE-99 poses high risk (RQ > 1) while BDE-209 posed medium risk (0.1 < RQ < 1). Though the concentration of DBDPE was several orders of magnitude higher than BDE209, its ecological risk was found to be negligible (RQ < 0.01). Thus, more attention is required to regulate the input (especially the e-waste recycling sites) of brominated flame retardants into the environment.

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.

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.

Multiple-life-stage probabilistic risk assessment for the exposure of Chinese population to PBDEs and risk managements

Studies assessing body burden of polybrominated diphenyl ethers (PBDEs) exposure have been conducted in the United States and Europe. However, the long-term assessment that is associated with multimedia exposure of PBDEs for the Chinese population is not available. The current study estimated the health risks using large PBDEs data to quantify the contributions of various media from different regions and distinguished the most vulnerable periods in life. We summarized media-specific (soil, dust, outdoor and indoor air, human milk and food) concentration of PBDEs in China from 2005 to 2016. Probabilistic risk assessment was adopted to estimate the health risks of infants, toddlers, children, teenagers and adults through ingestion, inhalation and dermal absorption. Monte Carlo simulation and sensitivity analysis were performed to quantify risk estimates uncertainties. E-waste areas had the highest PBDEs concentration, which was at least an order of magnitude higher than in other areas. BDE209 was the primary congener, accounting for 38-99% of the estimated daily intake. The dominant exposure pathway for infants was dietary intake through human milk, whereas dust ingestion was a higher contributing factor for toddlers, children, teenagers and adults. The 95th percentile of hazard index for infants and toddlers from e-waste areas of Guangdong and Zhejiang provinces exceeded one. Our estimates also suggested that infants may have the highest body burdens of PBDEs compared to other age groups. Sensitivity analyses indicated that PBDEs concentrations and ingestion rates contributed to major variances in the risk model. In this study, e-waste was found as a significant source of PBDEs, and PBDEs-containing e-waste are likely to be a threat to human health especially during early period of life. Risk strategies for better managing environmental PBDEs-exposure and human health are needed, due to the high intake of PBDEs and their persistence in the environment.

Sublethal or not? Responses of multiple biomarkers in Daphnia magna to single and joint effects of BDE-47 and BDE-209

Polybrominated diphenyl ethers (PBDEs) are extremely incessant anthropogenic contaminants found in the environment, with dreadful risk to aquatic ecosystems. However, there is a limited amount of data concerning their impacts on freshwater organisms. 2,2',3,3',4,4',5,5',6,6'-decabromodiphenyl ether (BDE-209) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) are significant components of total PBDEs in water. The sublethal effects of BDE-47, BDE-209 and their binary mixtures on the aquatic organism Daphnia magna were investigated in acute and chronic exposure experiments. Immobilization and heartbeat were studied in daphnids after 48 h of exposure. Mortality rate, breed number, Cholinesterase (ChE), Glutathione S-transferases (GST) and Catalase (CAT) activities were evaluated after 21 days of exposure. The results showed that at 100 and 200 μg/L concentration of BDE-47, immobilization rate of daphnids were inhibited by 44.0 ± 16.7% and 88.0 ± 10.9%, respectively. The binary mixture of BDE-47 and BDE-209 had uncongenial effects on immobilization of D. magna under acute toxicity test. BDE-209 significantly increased the heartbeat rate of daphnids, which increased even further when combined with BDE-47. After 21 days of exposure, daphnids exposed to single BDE-47 were physiologically altered. The combination of BDE-47 with BDE-209 significantly decreased the mortality rate of daphnids. Irrespective of the concentration, higher numbers of offsprings were produced in the mixtures compared to BDE-47 treatment alone. ChE activities significantly (p < 0.05) decreased at concentrations of 2 and 4 μg/L in single BDE-47 treatment, while GST activity significantly (p < 0.05) decreased at 0.5 μg/L. CAT activities significantly increased with BDE-47 treatments in all the tested concentrations (p < 0.05). The mixtures significantly affect ChE (p < 0.05), GST (p < 0.05) and CAT activities (p < 0.05). The results illustrated that the toxicity of the mixture of PBDE congeners exposed to aquatic organisms may have antagonistic effects. The 21 days chronic test in this study suggests that acute toxicity tests, i.e. 48-h tests, using Daphnia may lead to underestimation of risks associated with PBDEs, especially, BDE-209. Hence, there is a necessity to re-examine PBDE congeners' environmental risk in aquatic organisms.

A bibliometric analysis of investigations of polybrominated diphenyl ethers (PBDEs) in biological and environmental matrices from 1992 - 2018

The aim of this bibliometric analysis is to review the status and research evolution on the analysis of polybrominated diphenyl ethers (PBDEs) on biological and environmental matrices from January 1992 to February 2018 in the Web of Science focusing on original articles and reviews. One thousand four hundred and eighty two articles were found in the databases of the Web of Science on the analysis of PBDEs. Quantitative and qualitative parameters (countries, number of articles, frequency, average article citations and total average citations) were used to analyse each article and ranking of countries based on productivity, authors and article citation. Complementary analysis based on keywords was also done. The last decade experienced an increase in the analysis of this pollutant with the year 2012 recording the highest number of published articles (n = 137). High rate of collaboration with a very rich research network exists amongst institutions in Asian, European and America countries. China and USA are ranked 1st and 2nd on countries based on productivity, publishing 30% and 21.7% of the total articles respectively. South Africa was the only African country found in the category of countries based on productivity occupying the 17th position. The spectacular growth of research by researchers domiciled in China suggests the dominance of China in scientific research. This study suggests high research interest on this class of pollutant in developed countries. Additionally, lack of funds and sophisticated analytical tools may be responsible for lack of PBDEs-related studies in developing countries especially in Africa.

Adipose tissue levels of polybrominated diphenyl ethers and breast cancer risk in Chinese women: A case-control study

Polybrominated diphenyl ethers (PBDEs) are suspected to be associated with breast cancer risk because of their estrogenic potencies. Epidemiological studies of PBDEs and breast cancer are scarce. Our study aimed to estimate the association between adipose-tissue PBDE concentrations and breast cancer risk. A total of 209 breast cancer cases and 165 controls were recruited from hospitals between January 2014 and May 2016 in Shantou, Chaoshan area, China. Concentrations of 14 PBDE congeners were measured in adipose tissues obtained from the breast for cases and the abdomen/breast for controls during surgery. Demographic and clinicopathologic characteristics were obtained from medical records. Breast cancer risk as well as clinicopathologic characteristics were evaluated by adipose-tissue PBDE level. Odds ratios (ORs) and 95% confidence intervals (95% CIs) for breast cancer risk associated with levels of PBDE congeners were estimated from logistic regression models for all cases and stratified by estrogen receptor (ER) status. Level of total PBDEs (∑PBDE) and most individual PBDE congeners were higher in breast cancer cases than controls (median ∑PBDE, 94.99 vs 73.72 ng/g lipid). In the adjusted univariate model for all cases, breast cancer risk was increased with both 2nd and 3rd tertiles versus the 1st tertile of BDE-47 level (OR 2.05 [95% CI 1.08-3.92]; 5.47 [2.96-10.11]) and BDE-209 level (2.48 [1.30-4.73]; 4.72 [2.52-8.83]) with trend (both P < 0.001) and with the 3rd tertile of BDE-28 level (2.83 [1.63-4.92]), BDE-99 (3.22 [1.85-5.60]), BDE-100 (5.45 [2.90-10.23]), BDE-138 (2.40 [1.37-4.20]), BDE-153 (1.74 [1.02-2.97]), BDE-154 (1.84 [1.05-3.22]), and ∑PBDE levels (1.83 [1.07-3.14]) but decreased with the 3rd tertile of BDE-71 level (0.38 [0.22-0.65]) with trend (all P < 0.01). After stratifying by ER-positive or -negative status, the adjusted results were similar for ER-positive patients except for BDE-153 and BDE-154, with no statistical significance. In the multivariate model for all cases, age, menarche age, BDE-47, 71, 99, 100, 183 and 209 were independent factors associated with breast-cancer risk. ∑PBDE and most individual PBDE congeners investigated were positively associated with breast cancer risk in women from the Chaoshan area, China. PBDE may play a role in the occurrence and development of breast cancer.

Polybrominated diphenyl ethers in cord blood and perinatal outcomes from Laizhou Wan Birth Cohort, China

We explored whether polybrominated diphenyl ethers (PBDEs) exposed in cord blood could have any potential relationship with perinatal outcomes. Participants were pregnant females (n = 222) who were recruited from a prospective birth cohort (Laizhou Wan Birth Cohort, LWBC) between September 2010 and February 2012. We measured eight PBDE congeners (BDE-28, BDE-47, BDE-85, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183) in cord serum and examined their relationship with perinatal outcomes. The median levels of BDE-28, BDE-47, BDE-85, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183 were 2.92, 3.93, 2.29, 7.03, 3.03, 3.14, 1.46, and 2.55 ng/g lipids, respectively. For each log unit increase in BDE-47, BDE-100, and ∑₄PBDEs, gestational age increased by 0.70 weeks (95% confidence interval [CI] 0.25, 1.15), 0.48 weeks (95% CI 0.03, 0.94), and 0.73 weeks (95% CI 0.12, 1.34), respectively. We also found that BDE-47 was positively associated with head circumference (β = 0.42, 95% CI 0.00, 0.84). Given that our study area is one of the major brominated flame retardant production areas in China, and the cord PBDEs levels were relatively higher than those reported in most other Asian areas, more studies on the effects of in utero PBDE exposure on fetal growth and child development are warranted.

Gas/particle partitioning, particle-size distribution of atmospheric polybrominated diphenyl ethers in southeast Shanghai rural area and size-resolved predicting model

A size-segregated gas/particle partitioning coefficient K_Pi was proposed and evaluated in the predicting models on the basis of atmospheric polybrominated diphenyl ether (PBDE) field data comparing with the bulk coefficient K_P. Results revealed that the characteristics of atmospheric PBDEs in southeast Shanghai rural area were generally consistent with previous investigations, suggesting that this investigation was representative to the present pollution status of atmospheric PBDEs. K_Pi was generally greater than bulk K_P, indicating an overestimate of TSP (the mass concentration of total suspended particles) in the expression of bulk K_P. In predicting models, K_Pi led to a significant shift in regression lines as compared to K_P, thus it should be more cautious to investigate sorption mechanisms using the regression lines. The differences between the performances of K_Pi and K_P were helpful to explain some phenomenon in predicting investigations, such as P_L⁰ and K_OA models overestimate the particle fractions of PBDEs and the models work better at high temperature than at low temperature. Our findings are important because they enabled an insight into the influence of particle size on predicting models.

Polybrominated diphenyl ethers (PBDEs) in water, surface sediment, and suspended particulate matter from the Yellow River, China: Levels, spatial and seasonal distribution, and source contribution

Fourteen polybrominated diphenyl ether (PBDE) congeners were measured in water, suspended particulate matter (SPM), and sediment samples collected from the entire expanse of the Yellow River in dry and wet seasons. Higher concentrations of PBDEs were found in the middle and lower reaches of the river compared with those in the upper reaches, ascribed to the relatively developed and urbanized cities located in the areas near the middle and lower reaches. The PBDE concentrations in the samples collected during the dry season were lower than those in the samples collected during the wet season because of thaw and rainfall. The dominant congener, with a contribution of 44.6-90.3%, was BDE-209, which originated from the residual of commercial deca-BDE. Three groups of congeners in all the samples showed good correlations with the coefficient ranging from 0.662 to 0.999 (p < 0.01), indicating common sources and similar environmental behaviors. Regression analysis suggested that the local industrial product (IP) and population density (PD) were good indicators of PBDEs in the water and sediment of the Yellow River.

Temporal Changes and Stereoisomeric Compositions of 1,2,5,6,9,10-Hexabromocyclododecane and 1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane in Marine Mammals from the South China Sea

Stereoisomeric compositions of 1,2,5,6,9,10-hexabromocyclododecane (HBCD) and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) were investigated in the blubber of two species of marine mammals, finless porpoises ( Neophocaena phocaenoides) and Indo-Pacific humpback dolphins ( Sousa chinensis), from the South China Sea between 2005 and 2015. The concentrations of ΣHBCD in samples of porpoise ( n = 59) and dolphin ( n = 32) ranged from 97.2 to 6,260 ng/g lipid weight (lw) and from 447 to 45,800 ng/g lw, respectively, while those of ΣTBECH were both roughly 2 orders of magnitude lower. A significant increasing trend of ΣHBCD was found in dolphin blubber over the past decade. The diastereomeric profiles exhibited an absolute predominance of α-HBCD (mostly >90%), while the proportions of four TBECH diastereomers in the samples appeared similar. A preferential enrichment of the (-)-enantiomers of α-, β-, and γ-HBCD was found in most blubber samples. Interestingly, the body lengths of porpoises showed a significant negative correlation with the enantiomer fractions of α-HBCD. Significant racemic deviations were also observed for α-, γ-, and δ-TBECH enantiomeric pairs. This is the first report of the presence of TBECH enantiomers in the environment. The estimated hazard quotient indicates that there is a potential risk to dolphins due to HBCD exposure.

Distribution, accumulation profile, and risk assessment of polybrominated diphenyl ethers in sediment from lake and river systems in Hanoi Metropolitan Area, Vietnam

Concentrations of seven polybrominated diphenyl ethers (PBDEs) congeners were determined in surface sediments collected from several rivers and lakes in Hanoi, the capital city of Vietnam, to understand the status of background contamination, accumulation pattern, sources, and toxic implications for benthic organisms. Total PBDE concentrations in all sediment samples ranged from 0.03 to 17.5 ng/g dry weight (mean 1.33 ng/g dry wt). The most predominant congeners were BDE-47 and BDE-99, which comprised 30 and 25 % of total PBDE concentrations, respectively. Results from statistical analysis indicated that the potential sources of PBDEs of sediments in Hanoi may come from penta-BDE and octa-BDE mixtures. Risk quotients of PBDEs in sediments were also calculated for a benthic species, ranged from 2.12 × 10^-6 - 1.60 × 10^-2, and were markedly lower than threshold value for occurrence of any ecotoxicological risk. This study provides some of the most comprehensive data on the occurrence of PBDEs in sediments from lake and river systems in Vietnam.

Biodegradation of decabromodiphenyl ether (BDE 209) by a newly isolated bacterium from an e-waste recycling area

Polybrominated diphenyl ethers (PBDEs) have become widespread environmental pollutants all over the world. A newly isolated bacterium from an e-waste recycling area, Stenotrophomonas sp. strain WZN-1, can degrade decabromodiphenyl ether (BDE 209) effectively under aerobic conditions. Orthogonal test results showed that the optimum conditions for BDE 209 biodegradation were pH 5, 25 °C, 0.5% salinity, 150 mL minimal salt medium volume. Under the optimized condition, strain WZN-1 could degrade 55.15% of 65 μg/L BDE 209 under aerobic condition within 30 day incubation. Moreover, BDE 209 degradation kinetics was fitted to a first-order kinetics model. The biodegradation mechanism of BDE 209 by strain WZN-1 were supposed to be three possible metabolic pathways: debromination, hydroxylation, and ring opening processes. Four BDE 209 degradation genes, including one hydrolase, one dioxygenase and two dehalogenases, were identified based on the complete genome sequencing of strain WZN-1. The real-time qPCR demonstrated that the expression level of four identified genes were significantly induced by BDE 209, and they played an important role in the degradation process. This study is the first to demonstrate that the newly isolated Stenotrophomonas strain has an efficient BDE 209 degradation ability and would provide new insights for the microbial degradation of PBDEs.

Effects of coexisting BDE-47 on the migration and biodegradation of BDE-99 in river-based aquifer media recharged with reclaimed water

Two prominent polybrominated diphenyl ether (PBDE) congeners have been included in the persistent organic pollutant list, 2,2',4,4',5-tetrabromodiphenyl ether (BDE-99) and 2,2,4,4'-tetrabromodiphenyl ether (BDE-47), which have been detected in treated municipal wastewater, river water, and sediments in China. A lab-scale column experiment was established to investigate the effects of the competitive sorption of BDE-47 on BDE-99 biodegradation and migration in two types of river-based aquifer soils during groundwater recharge with reclaimed water. Two types of recharge columns were used, filled with either silty clay (SC) or black carbon-amended silty clay (BCA). The decay rate constants of BDE-99 in the BCA and SC systems were 0.186 and 0.13 m^-1 in the single-solute system and 0.128 and 0.071 m^-1 in the binary-solute system, respectively, showing that the decay of BDE-99 was inhibited by the coexistence of BDE-47. This was particularly evident in the SC system because the higher hydrophobicity of BDE-99 determined the higher affinity and competition for sorption sites onto black carbon. The biodegradation of BDE-99 was suppressed by the coexistence of BDE-47, especially in the SC system. Lesser-brominated congeners (BDE-47 and BDE-28) and higher-brominated congeners (BDE-100, BDE-153, BDE-154, and BDE-183) were generated in the four recharge systems, albeit at different ratios. Bacterial biodiversity was influenced by the presence of BDE-47 in the SC system, while it had no significant effect on the BCA system, because the high sorption capacity of black carbon on the hydrophobic PBDEs effectively reduced their toxicity. The ranking order of the most abundant classes changed markedly due to the coexistence of BDE-47 in both the SC and BCA systems. The ranking order of the most abundant genera changed from Azospira, Methylotenera, Desulfovibrio, Methylibium, and Bradyrhizobium to Halomonas, Hyphomicrobium, Pseudomonas, Methylophaga, and Shewanella, which could be involved in PBDE degradation.

Influence of human activities and organic matters on occurrence of polybrominated diphenyl ethers in marine sediment core: A case study in the Southern Yellow Sea, China

The Southern Yellow Sea (SYS) is an important reservoir of anthropogenic organic contaminants, such as polybrominated diphenyl ethers (PBDEs). To reconstruct the historical records of PBDEs and examine their relationships with the human activities and organic matters, a²¹⁰Pb-dated sediment core was collected from the central mud area in the SYS. The concentrations of tri-to hepta-BDEs (∑₇PBDEs) and BDE-209 ranged from 9.8 to 99.8 pg g^-1 d.w. and from 12.1 to 855.4 pg g^-1 d.w., respectively, both displaying the increasing trends from the bottom to the surface. More importantly, there was a faster increase for PBDEs since the 1990s, especially for BDE-209, which responded well with the rapid economic growth, and the increases of urbanization and industrialization in the local areas of the SYS. The analogously vertical patterns and significant relationships between PBDEs and total organic carbon (TOC) implied the TOC-dependent deposition of PBDEs in the core. Furthermore, multiple biomarker-based proxies of terrestrial organic matter (TOM) and marine organic matter (MOM) were introduced to systematically investigate the different effects of TOM and MOM on PBDE deposition in the SYS. The similarly down-core profiles and significant correlations were found between PBDEs and the MOM proxies (sum of rassicasterol, dinosterol and C₃₇ alkenones (∑A + B + D) and marine TOC) as well as the branched and isoprenoid tetraether (BIT), but not for TOM proxies (∑C₂₇+C₂₉+C₃₁n-alkanes, terrestrial and marine biomarker ratio (TMBR) and terrestrial TOC), indicating that MOM was an important factor driving PBDE deposition in the sediment core from the SYS.

Tissue-specific distribution and maternal transfer of polybrominated diphenyl ethers (PBDEs) and their metabolites in adult common sole (Solea solea L.) over an entire reproduction cycle

Tissue-specific accumulation and distribution of polybrominated diphenyl ethers (PBDEs) and their debrominated metabolites were studied in common sole (Solea solea) over an entire reproduction cycle. The fish were dietary-exposed to selected PBDEs in laboratory-controlled conditions for one year. Fish of both sexes were sampled throughout the reproduction cycle and their muscle, liver, viscera, carcass, skin and gonads (female) were analysed for total lipid content, PBDEs and their debrominated metabolites. On a wet weight basis, the concentrations of most spiked congeners showed an increase at the end of the exposure time in the whole body of fish of both sexes. Conversely, BDE-99 and BDE-209 - the two most highly metabolized congeners - did not show a similar increase, while their debrominated metabolites exhibited a linear increase over time. Biomagnification factors (BMFs) calculated in whole body were > 1 for all PBDEs except BDE-99 (0.89 ± 0.22) and BDE-209 (0.013 ± 0.006). BMFs were strongly correlated to apparent assimilation efficiencies, which ranged from 1.6% ± 0.7% (BDE-209) to 88% ± 11% (BDE-100). Fish carcass was the most predominant storage compartment for all PBDEs except BDE-209 in both male and female fish, followed by skin, muscle, female gonads, liver and visceral tissue. BDE-209 showed a different distribution and was stored more predominantly in the liver, viscera and female gonads than other congeners, probably due to its transport with lipoproteins. All PBDEs except BDE-209 showed equilibrium partitioning between the liver and other studied compartments, while BDE-209 showed a higher affinity with blood-enriched tissues, leading to higher liver / carcass, skin and muscle concentration ratios. Visceral tissue and liver exhibited the most pronounced differences in terms of concentration variations between sexes and over time. In females, both tissues showed a significant decrease in most PBDE concentrations (ww) and TLC in March during the spawning season, with low inter-individual variability, reflecting the striking utilisation of lipids by females for reproduction at this time. In males, no differences were found in concentrations in these compartments over time and a high inter-individual variability was observed. Maternal transfer of PBDEs from gonad to eggs was constant, regardless of spawn rank in the spawning season. Egg / gonad PBDE concentration ratios (in lw) were 1.3 ± 0.7 for all congeners and 2.6 ± 0.3 for BDE-209, suggesting a higher transfer of this congener from gonads to eggs.

Spatial distribution and implications to sources of halogenated flame retardants in riverine sediments of Taizhou, an intense e-waste recycling area in eastern China

Concentrations and spatial distribution pattern of organohalogen flame retardants were investigated in the riverine surface sediments from Taizhou, an intensive e-waste recycling region in China. The analytes were syn- and anti- Dechlorane Plus (DP), Dechloranes 602, 603, and 604, a DP monoadduct, two dechlorinated DPs and 8 congeners of polybrominated diphenyl ethers (PBDEs). The concentrations of Σ₈PBDEs, ΣDP, ΣDec600s, and ΣDP-degradates ranged from <100 to 172,000, 100 to 55,000, not detectable (nd) to 1600, and nd to 2800 pg/g dry weight, respectively. BDE-209 and DP, both have been manufactured in China, had similar spatial distribution patterns in the study area, featured by distinctly recognizable hotspots some of which are in proximity to known e-waste dumping or metal recycling facilities. Such patterns were largely shared by Dec602 and dechlorinated DP, although their concentration levels were much lower. These major flame retardants significantly correlate with each other, and cluster together in the loading plot of principle component analysis. In contrast, most non-deca PBDE congeners do not correlate with DPs. Dec604 stood out having distinctly different spatial distribution pattern, which could be linked to historical use of mirex. Organic matter content of the sediment was not the dominant factor in determining the spatial pattern of pollution by halogenated flame retardants in the rivers of this study.

Effect of anthraquinone-2,6-disulfonate on the photolysis of 2,4,4'-tribromophenylphenyl ether

In this study, we have investigated the photolysis of 2,4,4'-tribromophenylphenyl ether (BDE-28) in Triton X-100 (TX-100) solutions, and discussed the effect of anthraquinone-2,6-disulfonate (AQDS) on the photolysis of BDE-28. The effect of TX-100 on the photolysis of BDE-28 was mainly related to the concentration of TX-100. The fastest photolysis of BDE-28 was at 500 mg L^-1 of the TX-100 solution, and the corresponding photolysis rate constant was 0.12 min^-1. The direct photolysis rate of BDE-28 decreased from 0.17 min^-1 to 0.08 min^-1 and 0.12 min^-1 when NaN₃ and isopropanol were added, respectively. The effect of AQDS on the photolysis of BDE-28 was also mainly related to the concentration of AQDS. When the concentration of AQDS was 0.6 μM, it has a slight influence in promoting the photodegradation of BDE-28; as the AQDS concentrations increased, the suppressing effect was more obvious. AQDS can inhibit the photolysis of BDE-28. Photolysis kinetics and quenching reactions illustrated that BDE-28 can produce a photosensitization reaction in TX-100 solutions, and the effects of AQDS on the photolysis of BDE-28 were mainly dominated by inhibition. In addition to its light shielding effect, AQDS can also combine with BDE-28 and anti-oxidation to inhibit the photolysis of BDE-28. We found that the degradation pathway of BDE-28 was mainly based on de-bromination, and the ions at para positions were preferentially debrominated.

Treatment of decabromodiphenyl ether (BDE209) contaminated soil by solubilizer-enhanced electrokinetics coupled with ZVI-PRB

Decabromodiphenyl ether (BDE209) is a typical soil contaminant released from e-waste recycling sites (EWRSs). Electrokinetics (EK) has been considered as an excellent treatment technology with a promising potential to effectively remove organic pollutants in soil. In this study, the treatment of BDE209-polluted soil by EK was explored. All the EK experiments were conducted under a constant voltage gradient (2 V cm^-1) for 14 days. Deionized water (DI water), hydroxypropyl-β-cyclodextrin (HPCD), sodium dodecyl sulfate (SDS), and humic acid (HA) were applied as the processing fluid. The experimental results showed that all the solubilizers could effectively promote the mobility and transport of BDE209 in the soil via the electro-osmotic flow (EOF) or electromigration. The removal efficiencies achieved in S1 section were 24, 22, and 26% using HPCD, SDS, and HA as the processing fluid. However, the removal of BDE209 for the entire soil cell was not achieved until zero valence iron (ZVI) was inserted at the center of soil column as a permeable reactive barrier (PRB) or (ZVI-PRB), which enhanced the degradation of BDE209. As ZVI-PRB was installed in EK5 and EK6 experiments, the corresponding average removal efficiencies increased to 16 and 13%, respectively. Additionally, the degradation products of BDE209 analyzed by GC-MS suggested that debromination of BDE209 was the main potential degradation mechanism in the EK treatment in the presence of ZVI-PRB.

Polybrominated diphenyl ethers in articles: a review of its applications and legislation

Polybrominated diphenyl ethers (PBDEs), especially commercial decabrominated diphenyl ethers (c-decaBDE), have been widely produced and applied to numerous materials because of their highly effective flame-retardant capabilities. The production of commercial pentaBDE (c-pentaBDE) and commercial octaBDE (c-octaBDE) ended in 2004 because they are persistent, bioaccumulative, and toxic to both humans and the environment, but decaBDE production and use continue. Furthermore, many congeners of PBDEs are still prevalent in consumer products and articles that they pose enormous threat to both the environment and human health. PBDEs have been detected in the casing of electrical and electronic equipment, textile materials, automotive interiors, polyurethane foam (PUF) in seat cushions, children's toys, kitchenware, and other products. With increasing evidence about PBDE pollution and the adoption of international conventions, many developed countries have drawn more public attention to PBDEs and developed sound strategies for their management. This review summaries the utilization and management of PBDEs in a number of countries and reaches the conclusion that PBDEs are still prevalent in consumer articles, while specific regulations or policies for articles containing PBDEs are rare. Public awareness should be raised on the importance of sound management of articles containing PBDEs.

Dioxin-like activities, halogenated flame retardants, organophosphate esters and chlorinated paraffins in dust from Australia, the United Kingdom, Canada, Sweden and China

The concentrations of organic flame retardants (FRs) and dioxin-like activities in dust collected from five countries were investigated. The correlations between the concentrations of the different groups of FRs and dioxin-like activities were examined. Chlorinated paraffins (CPs, C₉ to C₃₁) were found in the highest concentration (median ∑CP 700 μg/g, range 280-4750 μg/g), followed by organophosphate esters (median ∑₁₃OPEs 56 μg/g, range 21-110 μg/g), halogenated flame retardants (median ∑₁₇HFRs 3.3 μg/g, range 0.87-14 μg/g) and polybrominated diphenyl ethers (median ∑₁₇PBDEs 2.8 μg/g, range 0.46-11 μg/g). There were no significant differences in concentrations of the FRs among the countries but differences in PBDE and CP congener profiles were found. BDE209 predominated in dust from Australia, the UK, Sweden and China, ranging from 50 to 70% of total PBDEs. The lowest percentage of BDE209 was found in the dust from Canada, representing only 20% of total PBDEs. For CPs in dust from Sweden, the long-chain CPs (especially C₁₈ congeners) predominated, while for other countries, medium-chain CPs (especially C₁₄ congeners) predominated. The dioxin-activities of the dusts ranged from 58 to 590 pg CALUX-TEQ/g, and had a median of 200 pg CALUX-TEQ/g. There were significant positive correlations between concentrations of PBDEs and CPs with dioxin-like activities. The dioxin-like activity may be due to the presence of polychlorinated or polybrominated dioxin/furans (PBDD/DFs) or polychlorinated naphthalenes (PCNs) in the dust. The PBDD/DFs are known impurities and degradation product of the penta-BDE mixture, and PCNs are known impurities of CPs which exhibit dioxin-like activities.