Concentrations Of Hexabromocyclododecane Research Articles

Persistent organic pollutants in the Antarctic marine environment: The influence impacts of human activity, regulations, and climate change

This study investigates the presence, distribution, and potential impacts of perfluoroalkyl substances (PFASs) and hexabromocyclododecanes (HBCDs) on the Antarctic marine environment. The analysis results from the King Sejong Station, the Jang Bogo Station, and Cape Evans revealed the highest concentrations of both PFASs and HBCDs at King Sejong Station, indicating the significant influence of human activity. Short-chain perfluorocarboxylic acids (PFCAs) dominated the seawater samples, with PFPeA at the highest concentration (0.076 ng/L) at King Sejong Station, whereas perfluorosulfonic acids (PFSAs) were prevalent in the sediments, with PFHxS reaching 0.985 ng/g. Total PFASs in benthos ranged from N.D. to 2.40 ng/g ww across all stations. This indicated the effects of long-range transport and glacial meltwater. α-HBCD was the most common diastereomer in benthos samples, detected in 58.3% of samples, suggesting its selective persistency. Although risk quotient analysis revealed low immediate risks to lower-trophic organisms, potential risks remain owing to their persistence and bioaccumulation potential. Contaminant patterns changed after regulations: perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) levels decreased, unregulated PFASs increased, HBCD stereoisomer ratios shifted towards α-HBCD dominance, and overall HBCD concentrations declined. Widespread persistence of regulated substances was observed in Antarctic environments, highlighting the need for comprehensive and long-term monitoring strategies. This study provides essential baseline data on contaminant distributions across the Southern Ocean, contributing to our understanding of emerging pollutants in Antarctic regions and informing future environmental protection efforts.

Reproductive toxicity of hexabromocyclododecane in rotifer Brachionus plicatilis: Involvement of reactive oxygen species and calcium signaling pathways

To assess the toxicity of Hexabromocyclododecane (HBCD), the population, individual, and cellular biochemical parameters of the rotifer Brachionus plicatilis exposed to different concentrations of HBCD were investigated. The results showed that the population growth rate, reproductive period, and offspring number in B. plicatilis significantly decreased under 324 μg/L and 648 μg/L HBCD. Antioxidant enzyme activity and mRNA expression of CAT and Mn-SOD were promoted at low concentrations (32 μg/L and 64 μg/L) and inhibited at high concentrations (324 μg/L and 648 μg/L), while MDA content accumulated continuously with increasing HBCD concentrations, indicating that HBCD induced oxidation imbalance in rotifers. Further evidence was provided by the correlation between DNA fragmentation and physiological changes. The increased intercellular concentration of Ca2+ and the expression of CaM mRNA suggested that HBCD activated pathways related to calcium signaling. In summary, the excessive production of ROS induced by HBCD was considered to be the main cause of reproductive toxicity.

Legacy halogenated flame retardants in Canadian human milk from the maternal-infant research on environmental chemicals study

Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) were measured in 298 human milk samples collected from across Canada between 2008 and 2011 as part of the Maternal-Infant Research on Environmental Chemicals study. PBDEs were detected in 100% of the samples analyzed and concentrations ranged from 0.071 to 267 ng·g-1 lipid (median 15.6 ng·g-1 lipid). The dominant contributors to ΣPBDEs (Σ15, 17, 28, 37, 47, 66, 71, 75, 77, 85, 99, 100, 119, 138, 153, 154, 160, 183, 190, 209) were PBDE 47 > PBDE 153 > PBDE 99 > PBDE 100 > PBDE 28 > PBDE 209. Previously, PBDE 209 was considered to be a minor contributor to ΣPBDE concentrations in Canadian human milk and, therefore, not reported by our lab. This study showed that when present, PBDE 209 can be an important contributor to ΣPBDEs (range: below detection - 85.3 ng·g-1 lipid; median - 0.083 ng·g-1 lipid). ΣPBDE concentrations declined slightly in Canadian human milk between the early and late 2000s. HBCD (Σ of α-, β-, and γ-) was observed in 94.0% of the samples measured and concentrations were dominated by α-HBCD (93.3%), with β- (9.7%) and γ- (28.5%) less frequently detected. The maximum ΣHBCD concentration observed was 7.66 ng·g-1 lipid (median value 0.303 ng·g-1 lipid). These data suggest that HBCD concentrations similarly decreased in Canadian human milk between the early 2000s and sampling for the present study. Maternal age did not impact the concentrations of these flame retardants in milk. Additionally, other maternal characteristics [e.g., the number of children a woman has had, pre-pregnancy body mass index (BMI), and education level] did not impact concentrations of these brominated flame retardant concentrations.

In vitro estimation of oral bioaccessibility of brominated flame retardants in indoor dust by fasted and fed physiologically extraction test

Aim: There is a dearth of information on in vitro oral bioaccessibility, challenging the evaluation of the health risks arising from indoor dust exposure to the brominated flame retardants, tetrabromobisphenol A (TBBPA), and hexabromocyclododecane (HBCDD). Here, we estimate the human oral bioaccessibility of TBBPA and HBCDD in indoor dust by applying the standardized bioaccessibility test under fasting (UBM-like test) and fed (FOREhST test) conditions. Methods: In vitro bioaccessibility of HBCDD and TBBPA of sixteen indoor dust samples was conducted under fasted and fed states. In the fed test, food components, including healthy and unhealthy food. The concentrations of HBCDD and TBBPA were analyzed using LC-MS/MS. Bioaccessibility was calculated from the ratio of the amount of HBCDD and TBBPA in a simulated gut solution to that in indoor dust. The average daily dose (EDDbioaccessibility) was calculated from the estimated daily intake and percentage of bioaccessibility. Results: The concentration of TBBPA and HBCDD in indoor dust ranged from 137 to 14,671 ng g-1 and < 0.7 to 528 ng g-1, respectively. A higher bioaccessible concentration was observed in the small intestine than in the stomach and mouth. The condition of the fed state with food containing fat showed greater bioaccessibility of TBBPA and HBCDD at 74.0% ± 9.5% and 62.2% ± 10.1%, respectively. In contrast, the fed state with lower fat food containing fiber presented the lowest bioaccessibility with a mean of 54.7% ± 10.7% for TBBPA and 53.7% ± 10.8% for HBCDD. Moreover, children are more exposed than adults, especially those who ingest indoor dust with fatty food. Conclusion: The oral bioaccessibility of TBBPA and HBCDD in indoor dust was highest in the fed state with fatty food, followed by fasted and fed states with lower fat, higher fiber food. Similarly, the estimated daily dose (EDDbioaccessibility) for children exceeded that for adults. Therefore, this study indicated that food consumption is a factor influencing the bioaccessibility of TBBPA and HBCDD present in indoor dust.

Inventorization and ecological risk assessment of tetrabromobisphenol A and hexabromocyclododecane in sediments from Guangdong coastal area of South China Sea

Brominated flame retardants (BFRs) exhibit excellent flame retardant properties and are widely used in various industries. Among the common BFRs, tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDs) pose substantial ecological and human health risks due to their extensive application and long-range transport. This study established 131 sample collection sites along the coast of the South China Sea (SCS) in Guangdong Province to assess the concentration, distribution, inventory, and ecological risk of TBBPA and HBCDs in surface sediments. The concentrations of TBBPA in SCS sediments ranged from < limit of detection (LOD) to 80 μg/kg dry weight (dw), and those of HBCDs from < LOD to 18 μg/kg dw. The diastereoisomers of HBCDs (α-, β-, and γ-HBCD) in the sediment samples accounted for 36 %, 13 %, and 51 %, respectively. Human activities, particularly those associated with nearby electronic waste disassembly and textile and garment industries, considerably influenced the dispersion of TBBPA and HBCDs. The inventories of TBBPA and HBCDs in Guangdong Province's SCS were estimated to be 3.2 × 105 kg and 7.2 × 104 kg, respectively. The average risk quotient values ranged from <0.01 to 0.016, indicating a low to negligible environmental risk. This study provides deeper insights into the distribution and scientific significance of HBCDs and TBBPA in SCS sediment samples, elucidates the current state of BFR contamination, and offers recommendations for future research on environmental safety and human health in the region.

Co-metabolic degradation and metabolite detection of hexabromocyclododecane by Shewanella oneidensis MR-1.

Hexabromocyclododecane (HBCD) is a widely used brominated flame retardant; however, it is a persistent organic pollutant as well as affects the human thyroid hormones and causes cancer. However, the degradation of HBCD has received little attention from researchers. Due to its bioaccumulative and hazardous properties, an appropriate strategy for its remediation is required. In this study, we investigated the biodegradation of HBCD using Shewanella oneidensis MR-1 under optimized conditions. The Box-Behnken design (BBD) was implemented for the optimization of the physical degradation parameters of HBCD. S. oneidensis MR-1 showed the best degradation performance at a temperature of 30 °C, pH 7, and agitation speed of 115 rpm, with an HBCD concentration of 1125 μg/L in mineral salt medium (MSM). The strain tolerated up to 2000 μg/L HBCD. Gas chromatography-mass spectrometry analysis identified three intermediates, including 2-bromo dodecane, 2,7,10-trimethyldodecane, and 4-methyl-1-decene. The results provide an insightful understanding of the biodegradation of HBCD by S. oneidensis MR-1 under optimized conditions and could pave the way for further eco-friendly applications. KEY POINTS: • HBCD biodegradation by Shewanella oneidensis • Optimization of HBCD biodegradation by the Box-Behnken analysis • Identification of useful metabolites from HBCD degradation.

A Review of Distribution and Profiles of HBCD in Different Environmental Media of China.

Hexabromocyclododecane (HBCD) is the most important flame retardant that has been used in Expanded Polystyrene foam and Extruded Polystyrene foam in the past forty years across the world. China was the major producer and user of HBCD, and the total HBCD production was about 0.3 million tons. Although HBCD was completely banned in China in 2021 because of its long-range transport, bioaccumulation and toxicity, there is still a lot of residue in the environment. Therefore, we reviewed multiple studies concerning the distribution of HBCD in diverse environmental matrices, such as in the air, dust, soil, water, sediment, and biota. Results revealed that HBCD levels in different environments in China present geographical variation and were at a high level compared with other countries. In all environmental media, relatively high HBCD concentrations have been found in industrial and urban areas. Industrialization and urbanization are two important factors that influence the concentration and distribution of HBCD in the environment. In terms of isomer, γ-HBCD was the dominant isomer in soil, water, and sediment, while in the biota α-HBCD was the predominant isomer.

The distribution and metabolism of hexabromocyclododecane isomers varies in the tissues of Nibea albiflora

Hexabromocyclododecanes (HBCDs), as brominated flame retardants, have increasingly drawn concern due to their detection in various marine organisms in recent years. The present test investigated the selective accumulation, depuration, and bioisomerization of HBCDs in different tissues and organs of Nibea albiflora, as well as the genetic metabolic behavior of HBCDs between parents and offspring. In a semi-static water environment, N. albiflora were exposed to individual HBCD diastereoisomers (α-HBCD, β-HBCD, or γ-HBCD) at a concentration of 0.4 μg/L for bioaccumulation, followed by clean food for depuration. During the exposure period, the highest concentrations of these HBCDs were observed in the intestine and gill of N. albiflora. α-HBCD was detected in all exposure groups, suggesting that both β-HBCD and γ-HBCD could be bioisomerized to α-HBCD in N. albiflora. In addition, there was no bioisomerization of α-HBCD to either β-HBCD or γ-HBCD, and there was no bioisomerization between β-HBCD and γ-HBCD. The half-lives (t1/2) were variable among different diastereoisomers, following an order of α-HBCD &amp;gt; γ-HBCD &amp;gt; β-HBCD. The most rapid depuration rate of HBCDs was discovered in the liver while muscle showed the least. Additionally, prior to spawning, the parent fish were exposed to contaminated feed (silkworms sprayed with 200 μL of a 30 μg/mL HBCD solution) for 6 days. By comparing the HBCDs concentrations in the maternal gonad, fertilized eggs, hatching eggs, larvae, and juveniles, it was determined that the maternal transfer coefficients for HBCDs were approximately 1, indicating dynamic equilibrium of HBCDs throughout the process from maternal tissue to progeny development. Differences in HBCDs pattern between organs observed in the experiment support a proposal of an organ-specific diastereomer accumulation.

Hexabromocyclododecane (HBCD) induced PANoptosis of chondrocytes via activation of the NLRP3 inflammasome and decreased the exercise ability of mice in vivo

Hexabromocyclododecane (HBCD) is a persistent organic pollutant (POP). HBCD is found in the blood and tissues of most populations and causes a range of toxicological damage to tissues and cells. However, the toxicological effects of HBCD on chondrocytes are not fully understood. Here, we evaluated the toxicological effects of HBCD on chondrocytes and cartilaginous tissue. For this, a model of primary cartilage cells was established. Chondrocytes were exposed to different concentrations of HBCD. Western blot, indirect immunofluorescence, ELISA and other biochemical experiments were performed to analyze the toxicological effects of HBCD on chondrocytes/articular cartilage tissue. Cell proliferation assays showed that HBCD caused a reduction in the proliferative capacity of chondrocytes, and further work indicated that HBCD induces chondrocyte death. Further experiments demonstrated that HBCD caused an inflammatory response in chondrocytes by evaluating the levels of inflammatory factors. We found that HBCD led to PANoptosis in chondrocytes by detecting panapoptosis-related marker molecules, and experimental data indicated that apoptosis markers (cleaved caspase-3/7), pyroptosis markers (caspase-1/GSDMD-N) and necroptosis markers (pMLKL/RIPK3) were upregulated after HBCD treatment. Subsequent experiments illustrated that HBCD activated the DAMP sensor NLRP3, which then mediated ZBP1-induced PANoptosis. In the in vivo model, the experimental animals were administered HBCD at 25, 50 and 100 µg/kg/week for 15 weeks. We found that HBCD led to an inflammatory response in articular cartilage tissue. The safranin O-fast green assay showed a certain degree of damage to cartilage tissue under HBCD treatment. Furthermore, HBCD resulted in an increase in MMP13 expression and a downregulation of COL2 expression in chondrocytes/cartilaginous tissues. HBCD decreased the exercise ability of mice in vivo. These data indicate that HBCD leads to chondrocyte damage. In summary, this study lays the foundation for further exploration of the toxicological effects of HBCD on bone and joints.

Spatial distribution, conversion, and ecological risk assessment of hexabromocyclododecanes in the sediments of black-odorous urban rivers nationwide in China

Hexabromocyclododecanes (HBCDs) have become a global pollution problem, particularly in China—a major producer and user of HBCDs. However, little is known about the HBCD pollution status in urban rivers nationwide in China. In this study, we comprehensively investigated the pollution characteristics of HBCDs in 173 sediment samples from black-odorous urban rivers across China. Total HBCD concentrations ranged from not-detected to 848 ng/g dw, showing significant differences among the various sampling cities, but generally increasing from west to east China. This distribution pattern of HBCDs was strongly associated with the local industrial output, gross domestic product, and daily wastewater treatment capacity. α-HBCD was the predominant diastereoisomer in most sediments, with an average proportion of 63.8 ± 18.8 %, followed by γ-HBCD (23.8 ± 19.5 %) and β-HBCD (12.4 ± 6.49 %), showing a significant increase of the α-HBCD proportions relative to those in HBCD commercial mixtures and an opposite trend for that of γ-HBCD. These results suggested that HBCDs might undergo isomerization from γ- to α-HBCD and biotic/abiotic degradation with preference for γ-HBCD. Of these conversions, the microbial degradation of HBCDs was further verified by the preferential transformation of (−)-α-, (+)-β-, and (−)-γ-HBCDs and the detection of HBCD-degrading bacteria, including Dehalococcoides, Bacillus, Sphingobium, and Pseudomonas. A risk assessment indicated that HBCDs pose low to moderate risks to aquatic organisms in most black-odorous urban river sediments.

Effects of hexabromocyclododecane and polyethylene microplastics on soil bacterial communities

Hexabromocyclododecane (HBCD) and polyethylene (PE) microplastic are ubiquitous pollutants, and knowledge about the effects of HBCD and PE pollution on soil bacterial communities remains obscure. In this study, the effects of different HBCD and PE concentrations and combined HBCD and PE exposure on the diversity, composition, and function of agricultural soil bacterial communities over 4 months were systematically examined for the first time. Generally, soil bacterial communities were influenced in both the 1-month and 4-month scenarios through HBCD and PE separately as well as combined exposure. After 4 months of exposure, PE and combined exposure significantly affected soil bacterial alpha diversity, however, low concentration of HBCD showed no apparent influence. 1-month and 4-month HBCD, PE, and combined exposure significantly influenced bacterial beta diversity. Compared with 1 month of exposure, HBCD, PE, and combined exposure demonstrated remarkable influences on soil bacteria after 4 months of exposure, especially on Nitrospirae, Elusimicrobia, Rokubacteria at the phylum level, and on MND1, Ruminiclostridium, Lysobacter, Anaeromyxobacter, Alistipes, WCHB1 at the genus level. The bacterial function analysis indicated that amino acid metabolism, carbohydrate metabolism, and membrane transport were the three predominant enriched bacterial functions after 1-month and 4-month HBCD and PE exposure. This research provides a comprehensive grasp of the effects of HBCD and PE pollution on soil microbial communities, which could have a beneficial impact on future soil pollution control.

Rising concentrations of polybrominated diphenyl ethers (PBDEs) in Nigerian foodstuffs despite global restrictions

The presence of brominated flame retardants (BFRs) in foodstuffs of African origin is poorly understood. To fill this gap, animal-derived food samples comprising 13 different items originally from Nigeria were obtained in 2021, and concentrations of novel brominated flame retardants (NBFRs), polybrominated diphenyl ethers (PBDEs), and hexabromocyclododecane (HBCDD) were measured. Arithmetic mean concentrations of NBFRs, PBDEs, and HBCDD in Nigerian foodstuffs were 2.1 ng/g (18 ng/g lipid weight (lw)), 1.3 ng/g (9.2 ng/g lw), and 0.42 ng/g (2.8 ng/g lw), with median concentrations of 1.7 ng/g (14 ng/g lw), 1.1 ng/g (8.2 ng/g lw), and <0.34 ng/g (<3.3 ng/g lw), respectively. Higher concentrations of NBFRs than of PBDEs and HBCDDs in Nigerian foodstuffs likely reflect use of NBFRs as substitutes for legacy BFRs in Nigeria. Comparison with previous dietary studies reveals rising concentrations of PBDEs in Nigerian foodstuffs in recent years with associated rises in dietary exposure, possibly due to active domestic use of PBDEs in Nigeria. Reassuringly, comparison of our exposure estimates with health-based limit values suggests adverse health effects of dietary intake of BFRs by Nigerians are unlikely to occur.

Brominated flame retardants in surface sediment from Western Guangdong, South China: Occurrence, distribution and toxicity in Caenorhabditis elegans

Sediment is the ultimate sink of environmental pollutants. A total of 128 surface sediment samples were collected from 8 rivers and 3 reservoirs in Maoming City, Guangdong Province. This study assessed the content and distribution of brominated flame retardants in sediments. The acute toxicity effects of tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDs) in sediments were evaluated using Caenorhabditis elegans as model organisms. The concentration of TBBPA in sediments ranged from not detected (ND) to 12.59 µg/kg and was mainly distributed in the central area, which was affected by the emission of TBBPA from residential and factory. The concentration of HBCDs ranged from ND to 6.31 µg/kg, and the diastereoisomer distribution was consistent, showing a trend close to the South China Sea. The composition pattern of HBCDs in the surface sediments from rivers were 41.73%–62.33%, 7.89%–25.54%, and 18.76%–40.65% for α-, β-, and γ-HBCD, respectively, and in the sediments from reservoirs were 26.15%–45.52%, 7.44%–19.23%, and 47.04%–61.89% for α-, β-, and γ-HBCD, respectively. When the sum of concentrations of TBBPA and HBCD in sediments were above high levels, reactive oxygen species in nematodes significantly increased, resulting in an oxidative stress response. Intestinal permeability was also enhanced, causing intestinal damage. In addition, in terms of this study, TBBPA had a greater impact on biotoxicity compared to HBCDs, and more attention should be paid to the toxic effects of the river ecosystem organisms in Maoming City, Guangdong Province. This study can complement the pollution database in the study area and provide basic data for pollution control.

Spatial and temporal change of tetrabromobisphenol A and hexabromocyclododecane in mangrove sediments from the Pearl River Estuary, South China

Spatial and temporal trends of tetrabromobisphenol (TBBPA) and hexabromocyclododecane (HBCD) in mangrove sediments from the Pearl River Estuary (PRE) in South China were evaluated. Concentrations of TBBPA and HBCD in mangrove sediments ranged from 0.23 to 13.3 and 0.36 to 54.7 ng g−1 dry weight. The highest TBBPA concentration was seen in Guangzhou mangrove wetland near a dockyard and a ferry terminal where TBBPA is utilized in the coatings for the shipbuilding industry. The rapid development of building might elucidate the higher concentrations of HBCD in Shenzhen mangrove sediments. γ-HBCD and α-HBCD was the two main diastereoisomer of HBCD in mangrove sediments with contributions of 56.1 % and 34.0 %. Sediments from the three PRE mangrove ecosystems were selectively enriched for (−)-γ-HBCD. TBBPA concentrations in mangrove sediments from Guangzhou rose during 2012–2015 and declined from 2015 to 2021. HBCD concentrations in the PRE mangrove sediments exhibited an increasing trend from 2012 to 2021.

Spatial distribution, source, and ecological risk of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) in Jiaozhou Bay, China

Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) are commonly found in the environment as components of brominated flame retardants. Due to their potential impact on human health and wildlife, it is imperative to closely monitor and manage their levels in the environment. This study investigated the spatial distribution, sources, and ecological risks of PBDEs and HBCDs in Jiaozhou Bay (JZB), a large bay situated on the eastern coast of China. The results showed that PBDE concentrations ranged from not detected (ND) to 7.93 ng/L in the water and ND to 65.76 ng/g in the sediment, while HBCD concentrations ranged from ND to 0.31 ng/L in the water and ND to 16.63 ng/g in the sediment. Furthermore, we observed significantly higher concentrations of PBDEs and HBCDs in the inner JZB compared to the outer JZB. Our source apportionment analysis showed that PBDEs primarily originated from the production and debromination of BDE-209, as well as the emission of commercial PeBDEs, whereas HBCDs in sediments mostly stemmed from anthropogenic activities and river input. Finally, our eco-logical risk assessment highlighted the need for continuous monitoring of PBDEs in JZB sediments. Overall, our study aims to provide valuable assistance for the environmental management of the JZB bay area, which is characterized by a complex net-work of rivers and a thriving economy.

Human health risk assessment from exposure to multiple sources of Hexabromocyclododecanes (HBCDs) in Taiwan

Hexabromocyclododecanes (HBCDs) are endocrine-disrupting and persistent organic compounds commonly used in consumer products such as styrofoam, fire-resistant curtains, construction, aquaculture products, and food containers. Humans can expose to HBCD via dermal, ingestion, and inhalation routes; however, the inhalation exposure to HBCDs is not well characterized, especially for the size-segregated particles, which could quickly deposit into the respiratory system. In this study, we systematically characterized the dermal and inhalation exposures and performed an aggregate risk assessment of HBCDs in Taiwan. Sampling sites were selected considering the traffic or industrial contribution for air (n = 2, Sanchung, and Taichung) and soil sampling (n = 19, near the industrial zones). The quantitative analysis of HBCDs in extracted samples was achieved using LC–MS/MS. Our results showed that the concentrations of total HBCDs ranged from 0.1 to 6.6 pg m−3 in the particulate matter samples and 0.63 to 187 μg kg−1 in soil samples, where γ-HBCD was the dominant species, followed by α-HBCD and β-HBCD. The total HBCDs in the finest particles (i.e., particle size below 0.49 μm) ranged from N.D. to 1.5 pg m−3. However, no consistent trend was observed for the isomer distribution of HBCDs among air samples. Furthermore, the margin of exposure was the lowest through the ingestion pathway (5152 to 22555) and the highest through the inhalation pathway (6.71 × 105 to 2.09 × 107), showing that HBCD-induced health risk can predominantly attribute to ingestion exposure. Nevertheless, the traffic and industrial contribution of inhalable HBCD deserves further studies.

Novel Brominated Flame Retardants in Dust from E-Waste-Dismantling Workplace in Central China: Contamination Status and Human Exposure Assessment.

Novel brominated flame retardants (NBFRs) have been widely used as alternatives to legacy BFRs. However, information on the contamination status and human exposure risks of electronic waste (e-waste)-derived NBFRs in the e-waste workplace is limited. In this study, six NBFRs and the legacy BFRs, hexabromocyclododecanes (HBCDs), were analyzed in 50 dust samples from an e-waste-dismantling workplace in Central China. The dust concentration of NBFRs in e-waste-dismantling workshops (median, 157-169 ng/g) was found to be significantly higher than those in an outdoor environment (17.3 ng/g) (p &lt; 0.01). Differently, the highest median concentration of HBCDs was found in dust from the dismantling workshop for cellphones and computers (367 ng/g) among studied areas. The bis(2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate (BEHTBP) was the predominant compound, which contributed 66.0-88.0% of measured NBFR concentrations. NBFRs might originate from plastic and rubber materials in wastes based on the correlation and principal component analysis. Moreover, the total estimated daily intakes (average scenario) of NBFRs were calculated at 2.64 × 10-2 ng/kg bw/d and 2.91× 10-2 ng/kg bw/d for the male and female dismantling workers, respectively, via dust ingestion, inhalation, and dermal contact pathways, which were lower than the reference dose values, and thus indicated a limited human exposure risk for NBFRs at the current level. Although the dust concentrations and daily intakes of NBFRs were still lower than those of other emerging pollutants (e.g., organophosphate and nitrogenous flame retardants) measured in the same sampling set, the elevated levels of NBFRs suggested the progressive BFR replacement process in China, which deserves more attention regarding their adverse effects on both the environment and human health.

Expanded polystyrene buoys as an important source of hexabromocyclododecanes for aquatic ecosystem: Evidence from field exposure with different substrates

The production and use of hexabromocyclododecanes (HBCDs) have been strictly limited due to their persistence, toxicity and bioaccumulation. However, the release of HBCDs from related products and wastes would continue for a long time, which may cause many environmental problems. In this study, we investigated the occurrence and distribution of HBCDs and microplastics (MPs) in aquatic organisms inhabiting different substrates. HBCDs were measurable in the seawater, sediment, expanded polystyrene (EPS) substrates and organism samples. Mostly, the concentrations of HBCDs in organisms inhabiting EPS buoys were significantly higher than those of the same species inhabiting other substrates. Meanwhile, the diastereomeric ratio (α/γ) of HBCDs in organisms inhabiting EPS buoys was closer to that in EPS buoys. The fugacity values of HBCDs in EPS buoys were much higher than those in other media, implying that HBCDs can be transferred from EPS buoys to other media. Additionally, MPs derived from EPS buoys would be mistaken as food and ingested by aquatic organisms. The transfer of HBCDs from EPS buoys to aquatic organisms can be achieved by aqueous and dietary exposures. In combination, the contribution of MP ingestion to HBCDs for aquatic organisms should be very limited. These results supported EPS buoys as an important source of HBCDs for the aquatic ecosystem. To effectively control HBCDs pollution, it is necessary to discontinue or reduce the use of EPS buoys.

Temporal trends in concentrations of brominated flame retardants in UK foodstuffs suggest active impacts of global phase-out of PBDEs and HBCDD

Global restrictions on use of legacy brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD) have generated demand for novel BFRs (NBFRs) as substitutes. Our research group has previously reported decreased concentrations of PBDEs and HBCDD and increased concentrations of NBFRs in UK indoor environments, suggesting that restrictions on PBDEs and HBCDD are exerting an impact. In this study, we analysed UK foodstuffs collected in 2020–21 and compared the BFR concentrations found with those found in similar samples collected in 2015 to investigate whether similar trends in BFR concentrations would be observed. Concentrations of PBDEs and HBCDD isomers detected in our samples had declined by 78–92 % and 59–97 % since the 2015 study, respectively. Moreover, concentrations of NBFRs (dominated by 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE or TBE), and bis(2-ethyl hexyl) tetrabromophthalate (BEH-TEBP or TBPH)) in UK foodstuffs increased significantly (28–1400 %) between 2015 and 2020–21. Combined, these findings suggest that restrictions on use of PBDEs and HBCDD have had a discernible impact on concentrations of these legacy BFRs and their NBFR replacements in UK foodstuffs. Interestingly, given recent reports of a significant increase in concentrations of decabromodiphenyl ethane (DBDPE) in UK house dust between 2014 and 2019, a significant decline (70–84 %) in concentrations of DBDPE was observed in UK foodstuffs.

Maternal Transfer and Apical and Physiological Effects of Dietary Hexabromocyclododecane Exposure in Parental Fathead Minnows (Pimephales promelas).

Hexabromocyclododecane (HBCD) is a persistent organic pollutant that has been characterized as an endocrine disruptor, undergoes maternal transfer, and hinders development and growth in oviparous organisms. The present study examined the apical effects of dietary HBCD (11.5, 36.4, 106 mg/kg, wet wt) on adult fathead minnow exposed for 49 days and the subsequent accumulation and maternal transfer kinetics in adult tissue and eggs, respectively. Exposed adults displayed a significant increase in egg production in the medium treatment group, but no other significant effects were noted. Maternal transfer of dietary HBCD had a similar egg-to-muscle ratios (EMR) in the low and medium treatment groups (1.65 and 1.27 [wet wt], respectively). However, the high treatment group deviated from other treatments with an EMR of 4.2 (wet wt), potentially due to differences in total lipid content in food and/or reaching diffusion/lipid saturation limits in adult tissue, resulting in lower accumulation in the adult muscle tissue. A positive correlation was observed between egg HBCD concentration and time of exposure, which indicates that maternal transfer of HBCD is of concern in fish, and further studies should be conducted to fully elucidate the potential adverse effects that may be observed in the early life stage of oviparous organisms. Environ Toxicol Chem 2023;42:143-153. © 2022 SETAC.