Simulation research on the natural degradation process of PBDEs in soil polluted by e-waste under increased concentrations of atmospheric O(3)

A critical review on BDE-209: Source, distribution, influencing factors, toxicity, and degradation

As the most widely used polybrominated diphenyl ether, BDE-209 is commonly used in polymer-based commercial and household products. Due to its unique physicochemical properties, BDE-209 is ubiquitous in a variety of environmental compartments and can be exposed to organisms in various ways and cause toxic effects. The present review outlines the current state of knowledge on the occurrence of BDE-209 in the environment, influencing factors, toxicity, and degradation. BDE-209 has been detected in various environmental matrices including air, soil, water, and sediment. Additionally, environmental factors such as organic matter, total suspended particulate, hydrodynamic, wind, and temperature affecting BDE-209 are specifically discussed. Toxicity studies suggest BDE-209 may cause systemic toxic effects on living organisms, reproductive toxicity, embryo-fetal toxicity, genetic toxicity, endocrine toxicity, neurotoxicity, immunotoxicity, and developmental toxicity, or even be carcinogenic. BDE-209 has toxic effects on organisms mainly through epigenetic regulation and induction of oxidative stress. Evidence regarding the degradation of BDE-209, including biodegradation, photodegradation, Fenton degradation, zero-valent iron degradation, chemical oxidative degradation, and microwave radiation degradation is summarized. This review may contribute to assessing the environmental risks of BDE-209 to help develop rational management plans.

Disentangling Source Profiles and Time Trends of Halogenated Flame Retardants in the Great Lakes

Thirty-five polybrominated diphenyl ethers (PBDEs) and eight other alternative flame retardants were measured in air samples (vapor plus particles) collected at six sites near the North American Great Lakes between 2005 and 2019 as part of the Integrated Atmospheric Deposition Network (IADN). These data were analyzed using a multiple linear regression model to determine spatial and temporal trends. Overall, the levels of flame retardants remain significantly higher in urban sites compared to rural and remote sites except for pentabromoethylbenzene (PBEB), hexabromobenzene (HBB), and total Dechlorane Plus (ΣDP). Here, we report the first findings of decreasing levels of ΣDP at Sturgeon Point, New York. The atmospheric levels of total PBDEs remain unchanged over time near Lakes Michigan and Superior and declined near Lakes Erie and Ontario, with rate constants at the latter two lakes revealing halving times of approximately 7 to 14 years. This work presents results from the first investigation of PBDE source apportionment in the Great Lakes atmosphere. Source apportionment by use of positive matrix factorization (PMF) identified two legacy commercial technical mixtures (i.e., penta-BDE and deca-BDE mixes) and elucidated a factor representing ambient degradation. Our results show that weathered local sources of technical commercial mixtures, and their photolysis contribute most to the total PBDE burden in the Great Lakes atmosphere.

Global PBDE contamination in cetaceans. A critical review

This review summarizes the most relevant information on PBDEs' occurrence and their impacts in cetaceans at global scale, with special attention on the species with the highest reported levels and therefore the most potentially impacted by the current and continuous release of these substances. This review also emphasizes the anthropogenic and environmental factors that could increase concentrations and associated risks for these species in the next future. High PBDE concentrations above the toxicity threshold and stationary trends have been related to continuous import of PBDE-containing products in cetaceans of Brazil and Australia, where PBDEs have never been produced. Non-decreasing levels documented in cetaceans from the Northwest Pacific Ocean might be linked to the increased e-waste import and ongoing production and use of deca-BDE that is still allowed in China. Moreover, high levels of PBDEs in some endangered species such as beluga whales (Delphinapterus leucas) in St. Lawrence Estuary and Southern Resident killer whales (Orcinus Orca) are influenced by the discharge of contaminated waters deriving from wastewater treatment plants. Climate change related processes such as enhanced long-range transport, re-emissions from secondary sources and shifts in migration habits could lead to greater exposure and accumulation of PBDEs in cetaceans, above all in those species living in the Arctic. In addition, increased rainfall could carry greater amount of contaminants to the marine environment, thereby, enhancing the exposure and accumulation especially for coastal species. Synergic effects of all these factors and ongoing emissions of PBDEs, expected to continue at least until 2050, could increase the degree of exposure and menace for cetacean populations. In this regard, it is necessary to improve current regulations on PBDEs and broader the knowledge about their toxicological effects, in order to assess health risks and support regulatory protection for cetacean species.

Effects of ferric ion on the photo-treatment of nonionic surfactant Brij35 washing waste containing 2,2',4,4'-terabromodiphenyl ether

The effects of ferric iron on the photo-treatment of simulated BDE-47 (2,2',4,4'- terabromodiphenyl ether)-Brij35 (Polyoxyethylene lauryl ether) washing waste were studied to evaluate the influences of ferric iron on BDE-47 removal and Brij35 recovery. The results show that Fe³⁺ accelerated BDE-47 degradation at lower concentrations (<0.5 mM) but attenuated it at higher concentrations (0.5-5 mM) and that Brij35 loss was increased with increasing Fe³⁺. These results likely are caused by changes in the rate of •OH production due to the ferric ion, association of Fe³⁺ and electron transfer from Brij35, and light attenuation at high concentration. The BDE-47 and Brij35 had different degradation rates at different pH values and at different dissolved oxygen concentrations. The BDE-47 products were identified by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). The results indicated that BDE-47 transformed into mainly lower-brominated products, a few bromodibenzofurans, some rearrangement products, and some hydroxylated polybrominated diphenyl ethers. A series of Brij35 oxidization products were detected by ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS), including hydroxylation products, carboxylation products, and some hydrophilic chain-breaking products. Brij35 was mainly oxidized by Fe³⁺ and/or reactive oxygen species (ROS) with the final products of CO₂ and H₂O. The iron ions apparently cycled from ferric to ferrous ions in the micelles such that the Fe³⁺-Brij35 complex dominated the main redox reaction, leading to both BDE-47 and Brij35 degradation. It appears that in any applied soil washing system, the ferric ions in the washing waste need to be removed because of the adverse effects on BDE-47 removal and eluate reuse.

Temporal and spatial surveys of polybromodiphenyl ethers (PBDEs) contamination of soil near a factory using PBDEs in northern Taiwan

Polybrominated diphenyl ethers (PBDEs), previously commonly used as flame retardants, should be monitored in the environment since some are listed as persistent organic pollutants. A contaminated site near a northern Taiwan factory using decabrominated diphenyl ether (deca-BDE) was identified based on a vegetable PBDEs monitoring project in 2013. The subsequent spatial and temporal survey of that contaminated site shows the contamination ingredients in soils were close to ones used by the factory, indicating that contamination was from the factory, possibly through an exhaust vent. The average concentration of deca-BDE in the main contaminated soil was 615 μg/kg d. w. (dry weight) soil in 2015, slightly decreasing to 604 μg/kg d. w. soil in 2016, increasing to 844 μg/kg d. w. soil in 2017, and then slightly decreasing to 670 μg/kg d. w. soil in 2018. The slight change of deca-BDE and the minor change in low brominated congener level indicate a low degradation rate. The contamination of peripheral sites was around 5000 μg/kg d. w. soil for one PBDEs sampling site that was higher than those around or within the main contaminated farm, indicating serious pollution. Concentrations of PBDEs in different soil depths show that depth 2-15 cm accounted for the greatest PBDEs accumulation, indicating that deca-BDE pollution had been present over time and transported into deeper soil. There can be PBDEs uptake by crops consumed by humans, as shown in our previous studies, so continuous monitoring of PBDEs in this site is important and treatments should be established urgently.

The brominated flame retardant PBDE 99 promotes adipogenesis via regulating mitotic clonal expansion and PPARγ expression

"Obesogens" have been widely accepted as chemicals that promote obesity, and there are many environmental pollutants that were functionally identified as obesogens. PBDE 99 is one of the most abundant PBDE congeners detected in human. However, its obesogenic effects are poorly understood. Here, we explore the in vitro effects of PBDE 99 on adipogenesis, which is a key process in obesogenesis. We observed an increase in adipogenesis when differentiating cells were exposed to PBDE 99. Further, the promoting effects of PBDE 99 on adipogenesis were most efficient during the first 4 days of 3T3-L1 differentiation. Consistent with this, early transcriptional factor CCAAT/enhancer-binding proteins β (C/EBPβ) was upregulated at Days 1 and 2 during differentiation, which is accompanied with the acceleration of mitotic clonal expansion (MCE) and the upregulation of terminal transcriptional factors C/EBPα and PPARγ2 from Day 2 or Day 4. Additionally, bisulfite genomic sequencing analysis revealed that PBDE 99 decreased methylation status of the CpG sites at PPARγ promoter region. Collectively, these findings demonstrate that PBDE 99 may be a potential environmental obesogen by promoting adipogenesis through facilitating MCE progression at early differentiation stage and upregulating key adipogenic factor PPARγ2 expression both in direct transcriptional and epigenetic regulation dependent manner.

Toxicity responses of bacterial community as a biological indicator after repeated exposure to lead (Pb) in the presence of decabromodiphenyl ether (BDE209)

Continuous exposure of chemicals could cause various environmental impacts. Decabromodiphenyl ether (BDE209) and lead (Pb) can co-exist and are discharged simultaneously at e-waste recycling sites (EWRSs). Extensive concerns have been attracted by their toxic effects on soil microorganisms. Thus, by using high-throughput sequencing, this study explored bacterial community responses in a soil system after repeated Pb exposure in the presence of BDE209 in the laboratory during 90-day indoor incubation period. Gene sequencing of 16S rDNA performed on an Illumina MiSeq platform proved that one-off Pb exposure caused higher microbial abundance and community diversity. Additionally, both repetitive Pb treatment and exogenous BDE209 input could change bacterial community composition. Twenty-three different bacterial phyla were detected in the soil samples, while more than 90% of the sequences in each treatment belonged to a narrow variety. The sequence analyses elucidated that Proteobacteria, Acidobacteria, and Bacteroidetes were the top three dominant phyla. Our observations could provide a few insights into the ecological risks of Pb and BDE209 co-existed contamination in soils at EWRSs.

A simulation research on the natural degradation process of tetrabromobisphenol A in soil under the atmospheric different environments

Tetrabromobisphenol A (TBBPA) is one of the most commonly used flame retardants and has become an environmental contaminant worldwide. More data on the basic characteristics of TBBPA are needed to better understand and used to describe its environmental fate. The aim of this study is to investigate the degradation of TBBPA with different degrees of bromination under the atmospheric different environments. TBBPA was removed quickly due to the strong oxidizing ability of ozone in the atmospheric environment. The half-life of TBBPA was approximately 2.5 h when the ozone concentration was 0.3 mg L(-1). The degradation reaction rates of TBBPA increase with increasing ozone concentration but decreased with increasing soil depth. When the ozone concentration was 10 mg L(-1), the removal rate of TBBPA reached 90.37 % at the soil surface after 2 h. Under UV irradiation, TBBPA was removed quickly, and the photodegradation reactions were faster than with solar irradiation. The conditions of alkaline soil and high ground temperature in the summer were both contributors to the degradation of TBBPA. These results could facilitate the improvement of waste treatment designs and could lead to better predictions of the outcome of TBBPA in the environment.