Legacy and emerging brominated flame retardants in China: A review on food and human milk contamination, human dietary exposure and risk assessment

The mother-offspring transfer of chlorothalonil through human breast milk: A multi-city cross-sectional study

4-Hydroxychlorothalonil (4-OH CHT), the main metabolite of chlorothalonil and the most widely used fungicide, has been frequently detected in human samples during monitoring. 4-OH CHT may exhibit higher toxicity and persistence in the environment compared to its prototype. In this study, a total of 540 paired serum and breast milk samples from pregnant women in three provinces in China were monitored for contaminant residues. 4-OH CHT was analyzed in the samples using ultra high-performance liquid chromatography - high-resolution mass spectrometry with a detection limit of 20 ng/L. The study investigated the effects of demographic factors, such as BMI, region of residence, and education level, on the levels of 4-OH CHT residues in serum and breast milk. Among the three provinces, the highest median concentration of 4-OH CHT in serum samples was observed in Hebei (1.04 × 103 ng/L), while the highest median concentration of 4-OH CHT in breast milk samples was observed in Hubei and Guangdong (491 ng/L). Multiple linear regression was used to investigate the significant positive correlation between 4-OH CHT in serum and breast milk (p = 0.000) after adjusting for personal characteristics. Based on this, the study further explored the influencing factors of transfer efficiencies (TEs) in conjunction with the individual TEs and the personal characteristics of the participants. Our results demonstrated that the age of the volunteers and their exercise habits had an effect on TEs, but further studies are needed to determine whether exercise leads to an increase in TEs.

ROS suppression and oocyte quality restoration: NMN intervention in decabromodiphenyl ether-exposed mice

Decabromodiphenyl ether (BDE-209) is an organic compound that is widely used in rubber, textile, electronics, plastics and other industries. It has been found that BDE-209 has a destructive effect on the reproductive system of mammals. However, the effect of BDE-209 exposure on oocyte quality and whether there is a viable salvage strategy have not been reported. Here, we report that murine oocytes exposed to BDE-209 produce a series of meiostic defects, including increased fragmentation rates and decreased PBE. Furthermore, exposure of oocytes to BDE-209 hinders mitochondrial function and disrupts mitochondrial integrity. Our observations show that supplementation with NMN successfully alleviated the meiosis impairment caused by BDE-209 and averted oocyte apoptosis by suppressing ROS generation. In conclusion, our findings suggest that NMN supplementation may be able to alleviate the oocyte quality impairment induced by BDE-209 exposure, providing a potential strategy for protecting oocytes from environmental pollutant exposure.

Functional Melanin Nanoparticles-Assisted Laser Desorption Ionization Mass Spectrometry for High-Sensitivity Detection of TBBPA and TBBPS Contaminations in Animal-Derived Foodstuffs

Tetrabromobisphenol A (TBBPA) and tetrabromobisphenol S (TBBPS) have been widely used as additives in various products; however, their residues damage human health mainly via dietary ingestion. The current detection techniques remain challenging in directly and sensitively identifying TBBPA and TBBPS from food samples. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has great potential as an alternative tool for the analysis of low-mass environmental pollution. Herein, we successfully screened and optimized COOH-MNP-COOH as a novel MALDI matrix to enhance deprotonation for the analysis of TBBPA and TBBPS from animal-derived food samples in negative-ion mode. Notably, COOH-MNP-COOH was synthesized by a facile self-assembly strategy and characterized by TEM, FT-IR, UV-vis, and zeta potential analysis. Compared with conventional and control matrices, the COOH-MNP-COOH matrix exhibited excellent performance of TBBPA and TBBPS with high chemical stability, favorable reproducibility, remarkable salt and protein tolerance, and high sensitivity owing to abundant active groups, stronger UV-vis absorption at 355 nm, and better hydrophilicity and biocompatibility. TBBPA and TBBPS were detected with the assistance of an internal standard with limits of detection (LODs) of 300 and 200 pg/mL, respectively. Moreover, this method was applied to directly identify the residues of TBBPA and TBBPS in milk products, followed by basa catfish and meat. This research may provide a promising approach for the analysis of environmental pollutants in foodstuffs.

Concentration of Tetrabromobisphenol-A in fish: systematic review and meta-analysis and probabilistic health risk assessment

Tetrabromobisphenol A (TBBP-A) is an emerging pollutant that enters water resources and affects various marine organisms, such as fish. Consequently, numerous studies globally investigated TBBP-A concentrations in fish fillets of the current study were meta-analyze concentration of TBBP-A in fish fillets and estimate the associated health risks for consumers. The search encompassed international databases, including Science Direct, PubMed, Scopus, Embase, and Web of Science from January 1, 2005, to July 20, 2023. The ranking of countries based on the pooled (Mean) concentration of TBBP-A in fish was as follows: China (1.157 µg/kg-ww) > Czech Republic (1.027 µg/kg-ww) > France (0.500 µg/kg-ww) ∼ Switzerland (0.500 µg/kg-ww) > Netherlands (0.405 µg/kg-ww) > Germany (0.33 µg/kg-ww) > Sweden (0.165 µg/kg-ww)>UK (0.078 µg/kg-ww) > Belgium (0.065 µg/kg-ww) > South Korea (0.013 µg/kg-ww) ∼ Japan (0.013 µg/kg-ww) > Ireland (0.005 µg/kg-ww). The risk assessment showed that the carcinogenic and non-carcinogenic risks of TBBP-A in China and France are higher compared to other countries; however, within all countries, these risks were found to be within acceptable limits.

Exposure levels and determinants of placental polybrominated diphenyl ethers in Chinese pregnant women

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) are a group of widely used chemicals and humans are exposed to them in their daily life. PBDEs exposure during pregnancy may have adverse effects on pregnant women and their fetuses. Nevertheless, limited information is available on the levels and determinants of PBDEs exposure in Chinese pregnant women.

METHODS

The internal exposure levels of eight PBDEs (BDE-28, 47, 99, 100, 153, 154, 183, and 209) in placental samples of 1280 pregnant women from Zunyi birth cohort were analyzed using gas chromatography tandem mass spectrometry. All PBDEs concentrations were lipid adjusted (ng/g lw). Determinants of exposure were assessed by multivariable logistic regression model.

RESULTS

Eight PBDE homologues were quantifiable in more than 70% of the samples. The highest median concentrations were found for BDE-209 (2.78 ng/g lw), followed by BDE-153 (1.00 ng/g lw) and BDE-183 (0.93 ng/g lw). The level of ΣPBDEs ranged from 0.90 to 308.78 ng/g lw, with a median concentration of 10.02 ng/g lw. Multivariate logistic regression analysis showed that maternal age older than 30 years old (OR: 1.59; 95% CI: 1.14, 2.23), pre-pregnancy obesity (1.51; 1.08, 2.10), home renovation within 2 years (1.43; 1.08, 1.91), spending more time outdoors during pregnancy (0.70; 0.55, 0.89), high consumption of fish/seafood (1.46; 1.13, 1.90) and eggs (1.44; 1.04, 2.00), male infant sex (1.69; 1.18, 2.42) were associated with PBDEs exposure.

CONCLUSION

The study population is generally exposed to PBDEs, of which BDE-209 is the dominant congener, indicating extensive application of products containing deca-BDE mixtures. Maternal age, pre-pregnancy BMI, home decoration, average outdoor time during pregnancy, fish, seafood, eggs consumption, and fetal sex were exposure-determinning factors. This study contributes to the knowledge on region-specific PBDEs contamination in pregnant women and related risk factors.

Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

Eight novel brominated flame retardants in indoor and outdoor dust samples from the E-waste recycling industrial park: Implications for human exposure

As alternatives for legacy brominated flame retardants, novel brominated flame retardants (NBFRs) have a wide array of applications in the electronic and electrical fields. The shift of recycling modes of electronic and electrical waste (e-waste) from informal recycling family workshop to formal recycling facilities might come with the change the chemical landscape emitted including NBFRs, however, little information is known about this topic. This study investigated the occurrence characteristics, distribution, and exposure profiles of eight common NBFRs and their derivatives in an e-waste recycling industrial park in central China and illustrated the differences in various functional zones in the recycling park. The highest level of ΣNBFRs in dust samples was found in e-waste storage area at median concentration of 27,400 ng/g, followed by e-waste dismantling workshops (23,300 ng/g), workshop outdoor area (7770 ng/g), and residential area outdoor (536 ng/g). In the e-waste dismantling associated dust samples, tetrabromobisphenol A bis(2,3-dibromopropyl ether) (TBBPA-BDBPE), tetrabromobisphenol A (TBBPA) and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) were the predominant components. This paper presented the first evidence regarding the occurrence characteristic and distribution of tetrabromobisphenol S (TBBPS), tetrabromobisphenol A bismethyl ether (TBBPA-BME) and tetrabromobisphenol S bis(2,3-dibromopropyl ether) (TBBPS-BDBPE) in the e-waste associated dust samples. By comparing with previous studies performed in China, this paper also noticed the significant decrease of TBBPA concentrations in the dust probably due to the shift of e-wastes sources and recycling modes. We further assessed the risk of occupational workers exposure to NBFRs. The median EDI (estimated daily intake) value of ΣNBFRs among e-waste dismantling workers was 9.71 ng/kg BW/d with the maximum EDI value being 19.6 ng/kg BW/d, hundreds of times higher than those exposed by general population. The study raises great concern for the health risk of occupational exposure to NBFRs in the e-waste recycling industrial park.

Multi-process regulation of novel brominated flame retardants: Environmentally friendly substitute design, screening and environmental risk regulation

Novel brominated flame retardants (NBFRs), one of the most widely used synthetic flame-retardant materials, have been considered as a new group of pollutants that potentially affect human health. To overcome the adverse effects of NBFRs, a systematic approach for molecular design, screening, and performance evaluation was developed to generate environmentally friendly NBFR derivatives with unaltered functionality. In the present study, the features of NBFRs (long-distance migration, biotoxicity, bioenrichment, and environmental persistence) were determined and characterized by the multifactor comprehensive characterization method with equal weight addition, and the similarity index analysis (CoMSIA) model was constructed. Based on the three-dimensional equipotential diagram of the target molecule 2-ethylhexyl tetrabromobenzoic acid (TBB), 23 TBB derivatives were designed. Of these, 22 derivatives with decreased environmental impact and unaltered functional properties (i.e., flame retardancy and stability) were selected using 3D-QSAR models and density functional theory methods. The health risks of these derivatives to humans were assessed by toxicokinetic analysis; the results narrowed down the number of candidates to three (Derivative-7, Derivative-10, and Derivative-15). The environmental impact of these candidates was further evaluated and regulated in the real-world environment by using molecular dynamics simulation assisted by the Taguchi experimental design method. The relationship between the binding effects and the nonbonding interaction resultant force (TBB derivatives-receptor proteins) was also studied, and it was found that the larger the modulus of the binding force, the stronger the binding ability of the two. This finding indicated that the environmental impact of the designed NBFR derivatives was decreased. The present study aimed to provide a new idea and method for designing NBFR substitutes and to provide theoretical support for restraining the potential environmental risks of NBFRs.

Recent progress and perspectives of metal organic frameworks (MOFs) for the detection of food contaminants

Over the past decades, increasing research in metal-organic frameworks (MOFs) being a large family of highly tunable porous materials with intrinsic physical properties, show propitious results for a wide range of applications in adsorption, separation, electrocatalysis, and electrochemical sensors. MOFs have received substantial attention in electrochemical sensors owing to their large surface area, active metal sites, high chemical and thermal stability, and tunable structure with adjustable pore diameters. Benefiting from the superior properties, MOFs and MOF-derived carbon materials act as promising electrode material for the detection of food contaminants. Although several reviews have been reported based on MOF and its nanocomposites for the detection of food contaminants using various analytical methods such as spectrometric, chromatographic, and capillary electrophoresis. But there no significant review has been devoted to MOF/and its derived carbon-based electrodes using electrochemical detection of food contaminants. Here we review and classify MOF-based electrodes over the period between 2017 and 2022, concerning synthetic procedures, electrode fabrication process, and the possible mechanism for detection of the food contaminants which include: heavy metals, antibiotics, mycotoxins, and pesticide residues. The merits and demerits of MOF as electrode material and the need for the fabrication of MOF and its composites/derivatives for the determination of food contaminants are discussed in detail. At last, the current opportunities, key challenges, and prospects in MOF for the development of smart sensing devices for future research in this field are envisioned.

Effective Extraction of Bisphenol Compounds from Milk with Stable Zr(IV)-Based Metal-Organic Framework Particles

Bisphenol compounds (BPs) have recently been the subject of growing interest due to their wide use in industrial and consumer products. Besides their adverse effects on human endocrine system, effective extraction of BPs and their elimination from complex sample matrix are still significant challenges in food analysis. Herein, a novel Zr(IV)-based metal-organic framework (MOF), named BUT-16, has been synthesized and utilized for the extraction and enrichment of BPs in milk samples. Bisphenol A (BPA), one of the highest production volume BPs, is used as a model molecule. The uptake capacity for BPA can reach up to 48 mg/g, and the adsorption rate is rapid (∼10 min), because of the larger surface area and cooperation of multiple functionalities of BUT-16. Employing BUT-16 in solid-phase extraction, coupled with ultra-performance liquid chromatography-tandem mass spectrometry detection, we generated a rapid, facile, and robust method for the enrichment and detection of trace BPA and its 12 substitutes in milk samples. After optimization, the limits of detection and quantification for BPs can be achieved as low as 0.05 and 0.2 ng/mL, respectively. Without the correction of the isotopic internal standard, the average recoveries of BPs at the different spiked concentrations varied from 63.8 to 120.6%, with a satisfactory precision (RSD ≤ 8.2%). Furthermore, the proposed method was successfully applied to the detection of BPs in real milk samples, and the results were in accordance with those of methods reported previously.

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.

An Analysis of the Structural Relationship between Thyroid Hormone-Signaling Disruption and Polybrominated Diphenyl Ethers: Potential Implications for Male Infertility

Polybrominated diphenyl ethers (PBDEs) are a common class of anthropogenic organobromine chemicals with fire-retardant properties and are extensively used in consumer products, such as electrical and electronic equipment, furniture, textiles, and foams. Due to their extensive use, PBDEs have wide eco-chemical dissemination and tend to bioaccumulate in wildlife and humans with many potential adverse health effects in humans, such as neurodevelopmental deficits, cancer, thyroid hormone disruption, dysfunction of reproductive system, and infertility. Many PBDEs have been listed as chemicals of international concern under the Stockholm Convention on Persistent Organic Pollutants. In this study, the aim was to investigate the structural interactions of PBDEs against thyroid hormone receptor (TRα) with potential implications in reproductive function. Structural binding of four PBDEs, i.e., BDE-28, BDE-100, BDE-153 and BDE-154 was investigated against the ligand binding pocket of TRα using Schrodinger's induced fit docking, followed by molecular interaction analysis and the binding energy estimation. The results indicated the stable and tight binding of all four PDBE ligands and similarity in the binding interaction pattern to that of TRα native ligand, triiodothyronine (T3). The estimated binding energy value for BDE-153 was the highest among four PBDEs and was more than that of T3. This was followed by BDE-154, which is approximately the same as that of TRα native ligand, T3. Furthermore, the value estimated for BDE-28 was the lowest; however, the binding energy value for BDE-100 was more than BDE-28 and close to that of TRα native ligand, T3. In conclusion, the results of our study suggested the thyroid signaling disruption potential of indicated ligands according to their binding energy order, which can possibly lead to disruption of reproductive function and infertility.

Legacy and novel brominated flame retardants in animal-derived foods from China Total Diet Study (CTDS): Temporal trends, evidence of substitution, and dietary exposure assessment

Based on the 6th China Total Diet Study (CTDS) conducted in 2016-2019, the occurrence of both legacy and novel brominated flame retardants (BFRs) was measured in animal-derived foods collected across China. Most BFRs could be frequently detected in food samples, indicating their ubiquity in the environment. Decabromodiphenyl ethane (DBDPE), a typical novel BFR, presented the highest contamination level, whereas legacy BFRs, including decabrominated diphenyl ether (BDE-209), tetrabromobisphenol A (TBBPA), and hexabromocyclododecane (HBCDD), still presented high detection frequencies and relatively abundant proportions in total BFRs. Compared with previous CTDSs conducted from 2007 to 2011, the levels and estimated dietary intakes (EDIs) of most BFRs showed a significant downtrend, which suggested that flame retardant consumption in China has transferred from legacy BFRs to novel BFRs (mainly DBDPE) and from BFRs to other kinds of flame retardants. Based on probabilistic estimation, the median EDIs of mainly used BFRs for the Chinese population ranged from 41.0 to 1.67 × 10³ pg/kg bw/day, and meat consumption was the primary source in dietary BFR intake. By conducting the margin of exposure (MOE) approach or comparing with the reference dose (RfD), it can be concluded that daily dietary intakes of BFRs were still unable to cause significant health risks to the general population in China.

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.

Occurrence, spatial distribution, and risk assessment of brominated flame retardants in farmland soils of typical provinces in China

In the present study, we investigated the occurrence, distribution, and potential risks of 4 brominated flame retardants in farmland soils across 18 provinces of China. The total mean concentrations of the BFRs were in order as DBDPE > BDE209 > HBB > TBB. DBDPE concentration was highest at 177.208 ng/kg, revealing its long-term use and persistence across the study areas. In parts of China, DBDPE was highest in the south (Sichuan, Shaanxi and Guangdong provinces), BDE209 was highest in the south (Sichuan province) and north (Jilin province), while HBB was highest in the south (Sichuan province) and east (Anhui and Zhejiang provinces) of China. Comparisons of the results in this study to other reported studies in different regions indicated that the studied BFRs concentrations were higher in the studied provinces of China. Pearson correlation between BFRs revealed both positive and negative associations within the BFRs groups and between BFRs and soil properties (SOM, CEC, pH, EC and PS%). The mean hazard quotients (HQ) of ecological risks ranged from 8.76 × 10^-6 to 1.16 × 10^-2 (HQ < 1) while non-carcinogenic human health risk evaluation for adults ranged from 7.05 × 10^-7 - 7.48 × 10^-4 (HQ < 1) and for children 2.99 × 10^-4 - 4.30 × 10^-2 (HQ < 1). Although the risk evaluations of BFRs from farmland soils in this study were low, the results serve as useful indicators of potential cumulative and long-term threats of BFR to rural areas where there is a high conversion of agricultural lands to non-agricultural use.

High cytotoxicity of a degraded TBBPA, dibromobisphenol A, through apoptotic and necrosis pathways

Halogenated flame retardants comprising bisphenol A (BPA) derivatives, such as tetrabromobisphenol A (TBBPA), have been studied their adverse effects on human health. However, despite the fact that these halogenated BPAs are easily degraded in the environment, the risks to living organisms due to these degraded products have mostly been overlooked. To evaluate the potential toxicity of degraded TBBPAs and related compounds, we examined the cytotoxicity of halogenated bisphenol A derivatives possessing one to four halogen atoms in vitro. The results indicated that the degraded TBBPA derivatives exhibited strong cytotoxicity against HeLa cells than TBBPA. Interestingly, the di-halogenated BPA derivatives possessing two halogen atoms exhibited the strongest cytotoxicity among tested compounds. In addition, a lactate dehydrogenase release assay, fluorescence spectroscopy and flow cytometry results indicated that dibromo-BPA and diiodo-BPA induced both apoptotic and necrotic cell death by damaging the cell membranes of HeLa cells. Moreover, Escherichia coli growth was inhibited in the presence of dehalogenated TBBPA and related compounds. These findings suggest that halogenated BPA derivatives that leak from various flame-retardant-containing products require strict monitoring, as not only TBBPA but also its degraded products in environment can exert adverse effects to human health.

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 < 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.

Evaluating the dynamic distribution process and potential exposure risk of chlorinated paraffins in indoor environments of Beijing, China

Chlorinated paraffins (CPs) are typical semi-volatile chemicals (SVOCs) that have been used in copious quantities in indoor material additives. SVOCs distribute dynamically between the gas phase and various condensate phases, especially organic films. Investigating the dynamic behaviors of existing CPs in indoor environments is necessary for understanding their potential risk to humans from indoor exposure. We investigate the distribution profiles of CPs in both gas phase and organic films in indoor environments of residential buildings in Beijing, China. The concentrations of CPs were in the range of 32.21-1447 ng/m³ in indoor air and in the range of 42.30-431.1 μg/m² and in organic films. Cooking frequency was identified as a key factor that affected the distribution profiles of CPs. Furthermore, a film/gas partitioning model was constructed to explore the transportation and fate of CPs. Interestingly, a re-emission phenomenon from organic films was observed for chemical groups with lower log K_oa components, and, importantly, their residue levels in indoor air were well predicted. The estimated exposure risk of CPs in indoor environment was obtained. For the first time, these results produced convincing evidence that the co-exposure risk of short-chain CPs (SCCPs), medium-chain CPs (MCCPs), and long-chain CPs (LCCPs) in indoor air could be further increased by film/gas distribution properties, which is relevant for performing risk assessments of exposure to these SVOCs in indoor environments.

Exposure to Novel Brominated Flame Retardants and Organophosphate Esters and Associations with Thyroid Cancer Risk: A Case-Control Study in Eastern China

Novel brominated flame retardant (NBFR) and organophosphate ester (OPE) exposure may engender adverse effects on human health. However, present epidemiological information regarding the effects of such exposure is limited and controversial. In this case-control study, 481 serum samples were collected from patients with thyroid cancer (n = 242) and healthy controls (n = 239) in Shandong Province, eastern China. The levels of NBFRs and OPEs, thyroid hormones, and serum lipid parameters were measured in all the participants. Pentabromotoluene, 2,3-dibromopropyl 2,4,6 tribromophenyl ether, decabromodiphenylethane (DBDPE), tris (2-chloroethyl) phosphate (TCEP), and triphenyl phosphate (TPP) were widely detected (detection frequency > 60%) in all the participants. A significantly high risk association was found between exposure of NBFRs and OPEs (namely 1,2,3,4,5-pentabromobenzene, DBDPE, tri-n-propyl phosphate, tri[(2R)-1-chloro-2-propyl] phosphate, tris (1,3-dichloro-2-propyl) phosphate, and tris (2-butoxyethyl) phosphate) and thyroid cancer in both males and females. In the females of the control group, TCEP levels exhibited a significantly positive association with thyroid-stimulating hormone and a negative association with triiodothyronine (T3), free triiodothyronine (FT3), and free thyroxine (FT4) levels. Weighted quantile sum regression evaluated the mixed effects of the compounds on thyroid hormones levels and thyroid cancer. As a result, TPP accounted for the majority of the T3, thyroxine, and FT3 amounts. Our results suggest that NBFR and OPE exposure contributes to alterations in thyroid function, thereby increasing thyroid cancer risk.

Toxicokinetics and edible tissues-specific bioaccumulation of decabrominated diphenyl ethers (BDE-209) after exposure to the broilers

Decabromodiphenyl ether (BDE-209), the primary constituent of a widely used flame retardant formulation, is often present in high levels in avian derived products and could be transferred to humans through consumption. The purpose of this study was to investigate the toxicokinetics and bioaccumulation patterns of BDE-209 in different tissues of broilers, which would benefit the evaluation of chicken product safety. Male broilers received a single oral administration of BDE-209 at 25 mg/kg.BW and then BDE-209 concentrations in the plasma, liver, leg muscle, breast muscle, and other tissues were measured using gas chromatography-electron capture detection (GC-ECD). The changes of BDE-209 concentrations in the plasma were fitted to a non-compartmental model for kinetic analysis. Peak values were observed at 24 h (t_1/2 =168.28 h), and trace levels remained for four weeks. Additionally, C_max in the liver was much higher than that in leg and breast muscles, and T_max from the liver and muscle were 12 and 24 h, respectively. Residual BDE-209 was detected in all broiler tissues after 2 weeks, and concentrations were ranked as follows: fat > liver > thymus gland > heart > testis > thigh muscle > skin > lung > kidney > breast muscles > spleen (wet weight (ww)). Our results suggested that BDE-209 was widely distributed in different tissues after intestinal absorption, and preferentially accumulated in adipose and liver tissues. Observations of bioaccumulation and slow elimination in the liver and muscles provide critical insight into the toxicity of BDE-209 and risk assessment of edible tissues from broilers.

Legacy and novel brominated flame retardants in air of Ny-Ålesund, Arctic from 2011 to 2019

Concentrations of polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs) in the atmosphere of Ny-Ålesund, Svalbard, were investigated. Passive air samples were collected for eight consecutive one-year periods from August 2011 to August 2019 at seven Arctic sampling sites. High-resolution gas chromatography coupled with high-resolution mass spectrometry (HRGC-HRMS) and gas chromatography coupled with election capture negative ionization mass spectrometry (GC-NCI-MS) were employed for PBDE and NBFR analysis, respectively. The median concentrations of Ʃ₁₁PBDEs and Ʃ₆NBFRs were 0.6 pg/m³ and 4.0 pg/m³, respectively. Hexabromobenzene and BDE-47 were the most abundant NBFR and PBDE congeners in the atmosphere, accounting for 31% and 24% of ƩNBFR and ƩPBDE concentrations, respectively. ƩNBFR concentration was approximately six times higher than that of ƩPBDEs in the same samples. Among NBFRs, the concentrations of 1,2,3,4,5-pentabromobenzene, 2,3,4,5,6-pentabromobenzene, and 2,3-dibromopropyl-2,4,6-tribromophenyl ether showed increasing temporal variations, with estimated doubling times of 3.0, 3.3, and 2.8 years, respectively. The concentrations of almost all PBDE congeners showed a decreasing variation, with halving times ranging from 2.1 to 9.5 years.

Assessing plant uptake of organic contaminants by food crops tomato, wheat, and corn through sap concentration factor

This study investigated uptake of two organic compounds including hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and exogenous caffeine by tomato (Solanum lycopersicum L.), corn (Zea mays L.), and wheat (Triticum aestivum L.). The plants were grown in a growth chamber under recommended conditions and then were exposed to these compounds for 19 days. The uptake of the compounds was measured by sap concentration factor. The plant samples (stem transpiration stream) and solution in the exposure media were taken and analyzed by high performance liquid chromatography-tandem mass spectrometry. The plant stem samples were analyzed after a freeze-thaw centrifugation process. The average sap concentration factor for the RDX by tomato, wheat, and corn was 0.71, 0.67, and 0.65. The average sap concentration factor for the exogenous caffeine by tomato, wheat, and corn was 0.72, 0.50, and 0.34. These relatively high sap concentration factor values were expected as available predictive models offer high sap concentration factor values for moderately hydrophobic and hydrophilic compounds. The generated sap concentration factor values for the RDX and exogenous caffeine are important for improving the accuracy of previously developed machine learning models predicting the uptake and translocation of emerging contaminants.

Tetrabromobisphenol A effects on differentiating mouse embryonic stem cells reveals unexpected impact on immune system

Tetrabromobisphenol A (TBBPA) is a potent flame retardant used in numerous appliances and a major pollutant in households and ecosystems. In vertebrates, it was shown to affect neurodevelopment, the hypothalamic-pituitary-gonadal axis and thyroid signaling, but its toxicity and modes of actions are still a matter of debate. The molecular phenotype resulting from exposure to TBBPA is only poorly described, especially at the level of transcriptome reprogramming, which further limits our understanding of its molecular toxicity. In this work, we combined functional genomics and system biology to provide a system-wide description of the transcriptomic alterations induced by TBBPA acting on differentiating mESCs, and provide potential new toxicity markers. We found that TBBPA-induced transcriptome reprogramming affect a large collection of genes loosely connected within the network of biological pathways, indicating widespread interferences on biological processes. We also found two hotspots of action: at the level of neuronal differentiation markers, and surprisingly, at the level of immune system functions, which has been largely overlooked until now. This effect is particularly strong, as terminal differentiation markers of both myeloid and lymphoid lineages are strongly reduced: the membrane T cell receptor (Cd79a, Cd79b), interleukin seven receptor (Il7r), macrophages cytokine receptor (Csf1r), monocyte chemokine receptor (Ccr2). Also, the high affinity IgE receptor (Fcer1g), a key mediator of allergic reactions, is strongly induced. Thus, the molecular imbalance induce by TBBPA may be stronger than initially realized.

Physiologically based pharmacokinetic (PBPK) modeling of BDE-209 following oral exposure in Chinese population

The wide usage of decabromodiphenyl ether (BDE-209) as additive brominated flame retardant has caused its widespread occurrence in the environment and high exposure risk in humans. Estimating its internal exposure dose and reconstruction of external exposure dose using physiologically based pharmacokinetic (PBPK) modelling approach is a key step in the risk assessment of BDE-209. However, the PBPK model for BDE-209 is currently unavailable. This study has established two oral permeability-limited PBPK models of BDE-209 without enterohepatic recirculation (EHR) (model 1) and with EHR (model 2) for Chinese population. Using the in vitro experiments, the average binding of BDE-209 to human plasma protein (99.64% ± 2.97%) was obtained. Moreover, blood sample analysis and systematic literature review were performed to obtain internal and external exposure data of BDE-209 used for model calibration and validation. The predictions of both models were within 2-fold of the observed, and a longer half-life of serum BDE-209 was observed in model 2 than model 1. Based on the models, a human biomonitoring guidance value (HBM-GV) of 93.61 μg/g lw was derived for BDE-209, and there is no health risk found for Chinese population currently. This study provides new quantitative assessment tools for health risk assessment of BDE-209.

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.

Environmentally relevant exposure to TBBPA and its analogues may not drastically affect human early cardiac development

Tetrabromobisphenol A (TBBPA) and its substitutes and derivatives have been widely used as halogenated flame retardants (HFRs), in the past few decades. As a consequence, these compounds are frequently detected in the environment, as well as human bodily fluids, especially umbilical cord blood and breast milk. This has raised awareness of their potential risks to fetuses and infants. In this study, we employed human embryonic stem cell differentiation models to assess the potential developmental toxicity of six TBBPA-like compounds, at human relevant nanomolar concentrations. To mimic early embryonic development, we utilized embryoid body-based 3D differentiation in presence of the six HFRs. Transcriptomics data showed that HFR exposure over 16 days of differentiation only interfered with the expression of a few genes, indicating those six HFRs may not have specific tissue/organ targets during embryonic development. Nevertheless, further analyses revealed that some cardiac-related genes were dysregulated. Since the heart is also the first organ to develop, we employed a cardiac differentiation model to analyze the six HFRs' potential developmental toxicity in more depth. Overall, HFRs of interest did not significantly disturb the canonical WNT pathway, which is an essential signal transduction pathway for cardiac development. In addition, the six HFRs showed only mild changes in gene expression levels for cardiomyocyte markers, such as NKX2.5, MYH7, and MYL4, as well as a significant down-regulation of some but not all the epicardial and smooth muscle cell markers selected. Taken together, our results show that the six studied HFRs, at human relevant concentrations, may impose negligible effects on embryogenesis and heart development. Nevertheless, higher exposure doses might affect the early stages of heart development.

Decabromodiphenyl ethane affects embryonic development by interfering with nuclear F-actin in zygotes and leads to cognitive and social disorders in offspring mice

Decabromodiphenyl ethane (DBDPE) is a novel retardant. DBDPE is used in various flammable consumer products such as electronics, building materials, textiles, and children's toys. The presence of DBDPE in humans makes it extremely urgent to assess the health effects of DBDPE exposure. Here, we used female mice as an animal model to investigate the effects of DBDPE on embryonic development and offspring health. The results showed that 50 μg/kg bw/day of DBDPE exposure did not affect spindle rotation in oocytes after fertilization, but led to a decrease of pronuclei (PN) in zygotes. Further investigation found that DBDPE interferes with the self-assembly of F-actin in PN, resulting in PN reduction, DNA damage, and reduced expression of zygotic genome activating genes, and finally leading to abnormal embryonic development. More importantly, we found that maternal DBDPE exposure did not affect the growth and development of the first generation of offspring (F1) mice, but resulted in behavioral defects in F1 mice. Female F1 mice from DBDPE-exposed mothers exhibited increased motor activity and deficits in social behavior. Both female and male F1 mice from DBDPE-exposed mothers exhibited cognitive memory impairment. These results suggest that DBDPE has developmental toxicity on embryos and has a cross-generational interference effect. It is suggested that people should pay attention to the reproductive toxicity of DBDPE. In addition, it also provides a reference for studying the origin of neurological diseases and indicates that adult diseases caused by environmental pollutants may have begun in the embryonic stage.

Human exposure to polybrominated diphenyl ethers (PBDEs) through the diet: An update of the scientific literature

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame-retardants (BFRs). As for other persistent organic pollutants, dietary intake (followed by dust inhalation) is the main route of human exposure to PBDEs. In 2012, we reviewed the scientific literature on the concentrations of PBDEs in foodstuffs and their dietary exposure. The current review is aimed at updating the results of recent studies (2012-2022) focused on determining the levels of PBDEs in food samples, as well as the dietary intake of these compounds. We have revised studies conducted over the world. The current information on the concentrations of PBDEs in food and their dietary intake is now much more notable than that available in our previous review, being China the country contributing with the highest number of studies. Because of the important differences in materials and methods used in the available studies, the comparison of results is certainly complicated. However, there seems to be a general trend towards a decrease in the levels of PBDEs in foods, and consequently, in the dietary intake of these contaminants. The lack of tolerable daily intakes of PBDEs is an issue that needs to be solved for assessing human health risks of these BFRs.

Long-Term Exposure to Decabromodiphenyl Ether Promotes the Proliferation and Tumourigenesis of Papillary Thyroid Carcinoma by Inhibiting TRß

Simple Summary

PBDEs have been reported to have endocrine-disrupting and tumour-promoting activity; however, the effects of BDE209 (the highest brominated PBDEs) on the thyroid and the underlying mechanisms are unclear. In this study, we found that long-term exposure to BDE209 could cause chronic toxicity and potential tumourigenesis by inhibiting the expression and function of TRß, which induces the proliferation of thyroid tissue and the oncogenesis of thyroid carcinoma. These findings emphasize the damaging effects that exposure to BDE209 has on human thyroid and papillary thyroid carcinoma.

Abstract

Polybrominated diphenyl ethers (PBDEs) have been reported to possess endocrine-disrupting and tumour-promoting activity. However, the effects of long-term exposure to decabromodiphenyl ether (BDE209) on thyroid tumourigenesis of papillary thyroid carcinoma (PTC) and the underlying mechanisms remain poorly defined. In this study, functional assays in vitro and mouse models in vivo were used to evaluate the toxic effects of long-term exposure to environmental concentrations of BDE209 on the pathogenesis and progression of PTC. MTS, EdU and colony-forming assays confirmed the chronic toxicity of BDE209 on the proliferation of human normal follicular epithelial cell line (Nthy-ori 3-1) and PTC-derived cell lines (TPC-1 and BCPAP). Wound and Transwell assays showed that BDE209 exacerbated the aggressiveness of PTC cells. BDE209 significantly promoted cell proliferation during the S and G2/M phases of the cell cycle. Mechanistically, BDE209 altered the thyroid system by acting as a competitive inhibitor of thyroid receptor beta (TRß) expression and function, which was further proven by public databases and RNA-seq bioinformation analysis. Taken together, these results demonstrated that BDE209 has chronic toxicity and potential tumourigenic effects on the thyroid by inhibiting TRß.

Tetrabromobisphenol A perturbs cell fate decisions via BMP signaling in the early embryonic development of zebrafish

Tetrabromobisphenol A (TBBPA) readily accumulates in the egg yolk of aquatic oviparous animals and is transferred to their embryos. Early embryogenesis is vital for organ formation and subsequent development. The developmental toxicity of TBBPA in aquatic animals has been extensively reported. However, few studies have assessed the toxic effects of TBBPA in the early embryonic development. In this work, we found that TBBPA perturbed cell fate decisions along the dorsal-ventral (DV) axis during gastrulation, further disrupting early organogenesis in the entire embryo. TBBPA exposure increased the number of embryonic cells that acquired a ventral cell fate, which formed epidermis, blood and heart tissues. In return, the number of embryonic cells that acquired a dorsal cell fate was greatly decreased, causing the TBBPA-exposed embryos to develop a small brain and small eyes. We revealed that TBBPA elevated the activity gradient of bone morphogenetic protein (BMP) signaling which is responsible for cell fate specification along the DV axis, with up-regulation of BMP ligands (bmp4, bmp7a) and target genes (szl) and promotion signal transduction through phosphorylation of Smad1/5. As the function of BMP signaling in embryogenesis is highly conserved among many vertebrates, these findings highlight the ecological and health risks of TBBPA.

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.

Decabromodiphenyl ether-induced PRKACA hypermethylation contributed to glycolipid metabolism disorder via regulating PKA/AMPK pathway in rat and L-02 cells

BDE-209 is the most prevalent congener of polybrominated diphenyl ethers and has high bioaccumulation in humans and animals. BDE-209 has been reported to disrupt glycolipid metabolism, but the mechanisms are still unclear. In this study, we found that BDE-209 induced liver tissue injury and hepatotoxicity, increased the glucose and total cholesterol levels in the serum of rats, and increased glucose and triglyceride levels in L-02 cells. BDE-209 exposure changed the PKA, p-PKA, AMPK, p-AMPK, ACC, and FAS expression in rats' liver and L-02 cells. Moreover, BDE-209 induced PRKACA-1 hypermethylation in L-02 cells. AMPK activator (AICAR) inhibited the changes of p-AMPK, ACC, and FAS expression and elevation of glucose and triglyceride levels induced by BDE-209. DNA methylation inhibitor (5-Aza-CdR) reversed BDE-209 induced alters of PKA/AMPK/ACC/FAS signaling pathway. These results demonstrated that BDE-209 could disrupt the glycolipid metabolism by causing PRKACA-1 hypermethylation to regulate the PKA/AMPK signaling pathway in hepatocytes.

Emerging and legacy flame retardants in indoor air and dust samples of Tarragona Province (Catalonia, Spain)

Flame retardants (FRs) are widely used in consumer products including furniture foam and electronic equipment such as computers, monitors and TVs. Over time, FRs can easily migrate into the surrounding environments. Since brominated FRs (BFRs) has been determined of high concern due to their environmental persistence, bioaccumulation and potential toxicity, novel FRs have emerged. The present study was aimed at identifying and quantifying the indoor levels of 41 legacy and novel FRs, which include 20 OPFRs and 21 HFRs (8 PBDEs, 3 HBCDDs, 5 NBFRs and 5 DECs) in Tarragona Province (Catalonia, Spain). The results have confirmed the presence of both legacy and novel FRs in air and dust of homes, schools and offices. To the best of our knowledge, this is the first European study measuring OPFRs at office environments and also confirming the presence of the following OPFRs: TEP, TCIPP, T2IPPP, TPPO, DCP, TMCP and B4IPPPP in indoor air, even some of them at high levels. OPFRs in general and TCIPP in particular showed high concentrations in air (94,599 pg/m³ and 72,281 pg/m³, respectively) and dust (32,084 ng/g and 13,496 ng/g, respectively) samples collected in indoor environments. HBCDDs were found at high levels in dust (32,185 ng/g), whereas the presence of PBDEs and DECs were low in both matrices (<160 pg/m³ in air and <832 ng/g in dust). NBFRs showed higher levels than the two legacy FRs groups, which is supported by the current restrictions of these FRs (640 pg/m³ in air and 1291 ng/g in dust). Samples of schools had significantly lower levels of NBFRs, but significantly higher concentrations of HFRs in air than in home samples, while dust levels of HFRs were significantly lower than those in samples of offices. Regarding human health risks, the current assessment suggests that those derived from exposure to FRs were lower -although close- to assumable risks, evidencing the potential of FRs for non-carcinogenic and carcinogenic risks, mainly due to the exposure to TCIPP, which was the main contributor together with ΣHBCDDs and also EHDPP.

Oxidative stress and endoplasmic reticulum stress contributed to hepatotoxicity of decabromodiphenyl ethane (DBDPE) in L-02 cells

Decabromodiphenyl ethane (DBDPE) is one of the most commonly used novel brominated flame retardants (NBFRs), and its mass production and widespread application have caused health threats to the human being. Existing studies have shown that DBDPE has hepatotoxicity. And we have found that DBDPE could change cytochrome P450 3A (CYP3A) expression levels in rat livers, whereas the mechanism is unclear. In this study, we exposed human normal hepatocyte (L-02) to DBDPE to further study the effect and mechanism of DBDPE on hepatocellular injury and liver metabolic enzyme CYP3A changes in vitro. The results showed that DBDPE caused L-02 cell viability decrease, lactate dehydrogenase (LDH) and transaminase release, ultrastructural damage, and apoptosis. Moreover, DBDPE exposure induced oxidative stress (i.e., increased ROS generation and MDA levels and decreased GSH content, SOD activity, and mitochondrial membrane potential) and endoplasmic reticulum (ER) stress in L-02 cells as evidenced by the elevated PERK and IRE-1α expression levels. These results confirmed that DBDPE is toxic to hepatocytes. Besides, the CYP3A expression level was decreased in DBDPE exposed L-02 cells. However, pretreatment of L-02 cells with antioxidant N-Acetyl-l-cysteine (NAC) and endoplasmic reticulum stress inhibitor 4-PBA inhibited DBDPE-induced oxidative stress, endoplasmic reticulum stress, CYP3A expression decrease, and apoptosis. Therefore, we demonstrated that DBDPE could exert toxic effects and decrease CYP3A expression on L-02 cells by inducing ER stress and oxidative stress.

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.

Decabromodiphenyl ether induces male reproductive toxicity by activating mitochondrial apoptotic pathway through glycolipid metabolism dysbiosis

Decabromodiphenyl ether (BDE-209), an extensively used flame retardant, exists widely in the environment. Although male reproductive toxicity induced by BDE-209 has been reported, its mechanisms remain unclear. To explore the role of glycolipid metabolism in male reproductive toxicity and the potential mechanisms, forty male SD rats were divided into four groups and given gavage with BDE-209 at 0, 5, 50, and 500 mg/kg/d for 28 days. In vitro, the spermatogenic cell lines GC-2spd cells were divided into four groups: the control group, 32 μg/mL BDE-209 group, 32 μg/mL BDE-209 + 0.4 μM Fatostatin (the inhibitor of SREBP-1) group, and 0.4 μM Fatostatin group. Our results showed that BDE-209 decreased sperm quality and quantity, which was correlated with glycolipid metabolism dysbiosis of testis. The levels of glucose, triglyceride, and total cholesterol were negatively correlated with sperm concentration, and triglyceride and total cholesterol levels were negatively correlated with sperm motility, while positively correlated with the sperm malformation rate. Moreover, BDE-209 exposure activated the glycolipid metabolism pathways (PPARγ/RXRα/SCAP/SREBP-1) and mitochondrial apoptotic pathway, thereby inducing the apoptosis of spermatogenic cells. In vitro, BDE-209 caused triglyceride and total cholesterol disorder and apoptosis of GC-2spd cells, the lipid metabolism pathways inhibitor fatostain downregulated the elevation of triglyceride and total cholesterol concentrations, and suppressed apoptosis and the activation of the mitochondrial apoptotic pathway in GC-2spd cells caused by BDE-209. Our results indicated that BDE-209 induced male reproductive toxicity by causing glycolipid metabolism dysbiosis of testis resulting in activating of the mitochondrial apoptotic pathway in spermatogenic cells. The study provides new insight into the mechanisms of male reproductive toxicity caused by BDE-209.

Legacy brominated flame retardants in human milk from the general population in Beijing, China: Biomonitoring, temporal trends from 2011 to 2018, and nursing infant's exposure assessment

Three kinds of legacy brominated flame retardants (BFRs), including eight polybrominated diphenyl ether (PBDE) congeners, tetrabromobisphenol A (TBBPA), and three hexabromocyclododecane (HBCDD) isomers, were analyzed in 105 human milk samples collected in 2018 from Beijing, China. The tested BFRs all showed high detection frequencies, and HBCDD was the most abundant BFR, with a median level of 7.64 × 10³ pg/g lipid, followed by BDE-153 (389 pg/g lipid), BDE-209 (283 pg/g lipid), and TBBPA (271 pg/g lipid). By comparing the results of the present study with those of our previous Beijing human milk surveys conducted in 2014 and 2011, the contamination of TBBPA and HBCDD increased steadily from 2011 to 2018, whereas that of PBDEs decreased sharply during this period. Our results suggested that the production and consumption of BFRs in China have shifted from PBDEs to other FRs. Education level and the consumption of animal-derived foods such as eggs and meat were identified as major influencing factors for some BFRs. For nursing infants, the median levels of lower bound BFR daily intake via human milk ingestion ranged from 4.62 × 10^-2 ng/kg bw/day for BDE-154 to 30.6 ng/kg bw/day for HBCDD. The daily intake of most BFRs by breastfeeding is unlikely to pose significant health risks for Beijing nursing infants. However, the minimum margin of exposure (MOE) of HBCDD was below its threshold value, which indicated that its daily intake might raise health concerns for some breastfed infants.

Occurrence and Dietary Intake of Organophosphate Esters via Animal-Origin Food Consumption in China: Results of a Chinese Total Diet Study

Although diet is regarded as a major exposure source of organophosphate esters (OPEs), the dietary survey of OPEs in China has been limited. Based on the sixth Chinese Total Diet Study (TDS) conducted during 2016-2019 in 24 of 34 provinces in China, 14 OPEs were detected in 96 food composites from four animal-origin food categories. Twelve OPEs were detected in more than 80% of the samples and 2-ethylhexyl diphenyl phosphate (EHDPP) presented the highest median concentration (1.63 ng/g wet weight (ww)). The most contaminated food composite was meat, with a median ∑₁₄OPEs of 13.6 ng/g ww, followed by aquatic food (11.5 ng/g ww), egg (7.63 ng/g ww), and milk (3.51 ng/g ww). The contribution of the meat group was close to or even greater than 50% in the estimated dietary intake (EDI) of OPEs. The average (range) EDI of the ∑₁₄OPEs via animal food consumption for a Chinese "standard man" was 34.4 (6.18-73.3) ng/kg bodyweight (bw)/day. The geographical distribution showed higher EDI in southern coastal provinces compared to the northern inland provinces. Nevertheless, the highest EDI of ∑₁₄OPEs from animal food was still more than 10 times lower than the reference dose. This is the first national survey of OPEs in foods from China.

Polychlorinated biphenyls (PCBs) in the colostrum samples from the Yangtze River Region: Exposure profile and risk assessment

Polychlorinated biphenyls (PCBs) may transfer into the neonates through the placental transfer and via breastfeeding after the delivery, thus might be harmful to the infant. Sixty colostrum samples in the Yangtze River Region were collected to investigate the concentration, distribution pattern, and enantiomer characteristic of the PCB exposure. Among all samples, over 90% of pollutants were tetra-to hepta-chlorinated PCBs. The sum concentration of the PCB was 512 (IQR: 322-856) ng g^-1 lipid weight. Enantiomer fraction (EF) of PCB 95 and PCB 149 was found lower than the racemic value, while EFs of PCB 45 and PCB 136 were found higher and near-racemic state, respectively. The concentration pattern and enantiomeric properties of the PCBs indicated that the mothers from Mianyang had a recent exposure to PCBs. Among all samples, similar exposure and metabolic pathways of the PCB congeners were observed. PCB exposure showed no significant correlation with the birth outcome of the infants, but 43.3% of the infants have potential health risks via breastfeeding.

Health toxicity effects of brominated flame retardants: From environmental to human exposure

Hexabromocyclododecane (HBCD) and Tetrabromobisphenol A (TBBP-A) are brominated flame retardants widely used in variety of industrial and consumer products (e.g., automobiles, electronics, furniture, textiles and plastics) to reduce flammability. HBCD and TBBPA can also contaminate the environment, mainly water, dust, air and soil, from which human exposure occurs. This constant exposure has raised some concerns against human health. These compounds can act as endocrine disruptors, a property that gives them the ability to interfere with hormonal function and quantity, when HBCD and TBBPA bind target tissues in the body. Studies in human and animals suggest a correlation between HBCD and TBBPA exposure and adverse health outcomes, namely thyroid disorders, neurobehavior and development disorders, reproductive health, immunological, oncological and cardiovascular diseases. However, in humans these effects are still poorly understood, once only a few data evaluated the human health effects. Thus, the purpose of this review is to present the toxicity effects of HBCD and TBBPA and how these compounds affect the environment and health, resorting to data and knowledge of 255 published papers from 1979 to 2020.

Modeling of Flame Retardants in Typical Urban Indoor Environments in China during 2010-2030: Influence of Policy and Decoration and Implications for Human Exposure

Novel flame retardants (FRs) are of increasing concern, given growing evidence of health effects and use to replace polybrominated diphenyl ethers (PBDEs). This study modeled combined effects of use policies and decoration on indoor FRs and human exposure for 18 widely used PBDEs, organophosphate esters (OPEs), and novel brominated flame retardants in typical urban indoor environments in China. The current estimated indoor emission rates and average concentrations in air and dust of the 18 FRs were 10²-10³ ng/h, 561 ng/m³, and 1.5 × 10⁴ ng/g, respectively, with seven OPEs dominant (>69%). Different use patterns exist between China and the US and Europe. Scenarios modeled over 2010-2030 suggested that decoration would affect indoor concentrations of FRs more than use policies, and use policies were mainly responsible for shifts of FR composition. Additional use of hexabromobenzene and 2,3,4,5,6-pentabromotoluene and removal of BDE-209 would make the total human exposure to the modeled FR mixture increase after the restriction of penta- and octa-BDE but decrease after deca-BDE was banned. Better knowledge of the toxicity of substitutes is needed for a complete understanding of the health implications of such changes. Toddlers may be more affected by use changes than adults. Such studies are supportive to the management of FR use.

Risk Characterization and Benefit-Risk Assessment of Brominated Flame Retardant in Commercially Exploited Freshwater Fishes and Crayfish of Lake Trasimeno, Italy

Among brominated flame retardants (BFRs), polybrominateddiphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) were the most widely used in past decades. BFRs not being chemically bonded to polymers means they can easily leach from the products into the environment and bioaccumulate. Humans are exposed to flame retardants mainly through food consumption, especially fish and fish products. In the present study, the occurrence of PBDEs and HBCDs in freshwater fishes and crayfish from Lake Trasimeno (Umbria region, central Italy) was assessed according to monitoring plans recommended by European competent authorities. The dietary exposure of the central Italian population to such molecules was calculated, and the risk characterization and the benefit–risk evaluation were also assessed. A total of 90 samples were analyzed by means of gas and liquid chromatography associated with triple quadrupole mass spectroscopy. A total of 51% of samples were found positive for at least one of the congeners; the most frequently found molecule was BDE-47. The data on dietary exposure ranged from 0.138 to 1.113 pg/kg body weight/day for ∑PBDE and from 0.805 to 0.868 pg/kg body weight/day for ∑HBCD. The data show no health risks for the central Italian population consuming freshwater fish products from Lake Trasimeno in relation to exposure to PBDE and HBCD.

Emerging Brominated Flame Retardants 2-Ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB) and Bis(2-ethylhexyl)-tetrabromophthalate (BEH-TEBP) in Chinese Food and Their Health Implications

2-Ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB) and bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP) have been frequently detected in the environment, whereas studies in food are scare. The European Food Safety Authority has requested data for their risk assessment. Herein, dietary exposure and hazard quotient (HQ) were studied based on the 5th (2009-2012) and 6th (2015-2018) Chinese total diet studies (TDSs). EHTBB was found in 61.1 and 75.9% of the two TDS sample sets, respectively. The concentrations of EHTBB in animal-derived food were higher than those in plant-derived food. The estimated daily intakes (EDIs) were 1.33 and 0.97 ng/kg bw/day, and vegetables contributed to 48.5 and 39.2% of the EDIs based on the 5th and 6th TDS, respectively. The dietary exposure to EHTBB was similar to that to hexabromocyclododecane, brominated diphenyl ether-209, and tetrabromobisphenol A (TBBPA). The HQ for EHTBB was similar to that for decabromodiphenyl ethane and surpassed that for TBBPA. Therefore, EHTBB warrants further study in food.

Organophosphorus flame retardants in breast milk from Beijing, China: Occurrence, nursing infant's exposure and risk assessment

Organophosphorus flame retardants (OPFRs) are widely used chemicals, whereas data on OPFRs in human being is limited. In this study, thirteen OPFRs were measured in 105 breast milk samples collected from Beijing mothers in 2018. The ∑₁₃OPFRs ranged from <LOD to 106 ng mL^-1 (<LOD-6700 ng g^-1 lipid weight (lw)), with a median value 10.6 ng mL^-1 (157 ng g^-1 lw). The most abundant compound was tris(2-ethylhexyl) phosphate (TEHP), followed by triphenyl phosphate (TPhP) and 2-ethylhexyl diphenyl phosphate (EHDPP). The detecting frequencies and contamination levels of OPFRs in our study were higher than those reported in other studies, which indicated that China is one of the most affected regions by OPFRs. In addition, OPFR levels in our study were found to be higher than levels of brominated flame retardants (BFRs) in human milk from China. Based on regression analyses, mothers' personal characters, including age, pregnancy, residing/working location, and educational level were found to be impact factors of some OPFRs in breast milk. Estimated daily intakes (EDI) of the OPFRs for nursing infants via human milk ingest were calculated, and the mean EDIs of the 13 OPFRs ranged from 2.62 to 1640 ng kg^-1 bw d^-1. Since the mean and max EDIs of most OPFRs were lower than corresponding reference doses (RfDs), the daily OPFR intake for most nursing infants would not cause significant health concerns. However, the max EDIs of two OPFRs, TPhP and EHDPP, with values of 1.09 × 10⁴ and 2190 ng kg^-1 bw d^-1, respectively, were higher than their corresponding RfDs. To our knowledge, this is the first report on the occurrence of OPFRs in human milk from China.

2,2'4,4'-Tetrabromodiphenyl Ether (PBDE-47) Modulates the Intracellular miRNA Profile, sEV Biogenesis and Their miRNA Cargo Exacerbating the LPS-Induced Pro-Inflammatory Response in THP-1 Macrophages

The 2,2’4,4’-tetrabromodiphenyl ether (PBDE-47) is one of the most prominent PBDE congeners detected in the environment and in animal and human tissues. Animal model experiments suggested the occurrence of PBDE-induced immunotoxicity leading to different outcomes and recently we demonstrated that this substance can impair macrophage and basophil activities. In this manuscript, we decided to further examine the effects induced by PBDE-47 treatment on innate immune response by looking at the intracellular expression profile of miRNAs as well as the biogenesis, cargo content and activity of human M(LPS) macrophage cell-derived small extracellular vesicles (sEVs). Microarray and in silico analysis demonstrated that PBDE-47 can induce some epigenetic effects in M(LPS) THP-1 cells modulating the expression of a set of intracellular miRNAs involved in biological pathways regulating the expression of estrogen-mediated signaling and immune responses with particular reference to M1/M2 differentiation. In addition to the cell-intrinsic modulation of intracellular miRNAs, we demonstrated that PBDE-47 could also interfere with the biogenesis of sEVs increasing their number and selecting a de novo population of sEVs. Moreover, PBDE-47 induced the overload of specific immune related miRNAs in PBDE-47 derived sEVs. Finally, culture experiments with naïve M(LPS) macrophages demonstrated that purified PBDE-47 derived sEVs can modulate macrophage immune response exacerbating the LPS-induced pro-inflammatory response inducing the overexpression of the IL-6 and the MMP9 genes. Data from this study demonstrated that PBDE-47 can perturb the innate immune response at different levels modulating the intracellular expression of miRNAs but also interfering with the biogenesis, cargo content and functional activity of M(LPS) macrophage cell-derived sEVs.

Assessment of polybrominated diphenyl ethers and emerging brominated flame retardants in Pheretima (a Traditional Chinese Medicine): Occurrence, residue profiles, and potential health risks

China produces and consumes large quantities of brominated flame retardants (BFRs) as well as several other unregulated electronic waste recycling activities, causing high BFR concentrations in the natural environment. Thus, Traditional Chinese Medicines (TCMs) may be contaminated by legacy BFRs (e.g. polybrominated diphenyl ethers (PBDEs)) and emerging BFRs (eBFRs, such as decabromodiphenyl ethane (DBDPE)) during growth, processing, packaging, and transportation. Pheretima, which is a typical animal drug recorded in Chinese Pharmacopoeia, was used as an example to evaluate human exposure to BFRs through TCM intake. This study is the first to determine 25 PBDEs and 5 eBFRs in Pheretima and estimate the daily BFR intake via Pheretima-containing TCMs. Twenty-seven Shanghai Pheretima and fifty-one Guang Pheretima samples were collected between March and June 2019 in southeast China. High BFR detection frequencies were found in Pheretima, of which BDE-209 and DBDPE were the most predominant analytes. The total PBDE contents ranged from 73 pg/g to 8,725 pg/g, while that of the eBFRs varied between 115 pg/g and 2,824 pg/g. The profiles and abundances were found to be species- and origin-dependent. However, the traditional processing of Pheretima may reduce BFR residues. Based on the usual clinical doses of Pheretima and the available chronic oral reference doses of BDE-47, 99, 153, and 209, the mean (95th percentile) of the total hazard quotient was estimated to be 9.1 × 10^-5 (2.7 × 10^-4). Therefore, there is little risk related to BFR exposure for patients taking formulated Pheretima-containing TCMs. However, it is necessary to establish routine monitoring programs for the co-existence of pollutants in TCMs to perform a systematic and comprehensive risk assessment.

Decabromodiphenyl ether disturbs hepatic glycolipid metabolism by regulating the PI3K/AKT/GLUT4 and mTOR/PPARγ/RXRα pathway in mice and L02 cells

Decabromodiphenyl ether (BDE-209) is a persistent environmental pollutant that poses great risks to human health and has been associated with glucose and lipid metabolism. However, the mechanisms by which BDE-209 disturbs glycolipid metabolism in the liver remain unclear. Therefore, this study sought to confirm the effects of BDE-209 on glycolipid metabolism in mice livers and L02 cells to elucidate potential mechanisms of action. In vivo BDE-209 exposure caused histological damage and lipid accumulation, elevated glucose, low-density lipoprotein, total cholesterol, and triglyceride levels, and decreased glycogen and high-density lipoprotein levels in mice livers. Moreover, in vitro BDE-209 exposure not only induced L02 cells cytotoxicity (i.e., reduced cell viability and increased LDH leakage and ROS generation) but also increased glucose and triglyceride concentrations in L02 cells. Furthermore, IGF-1, an activator of the PI3K-AKT pathway, markedly inhibited BDE-209-induced glucose concentration increase in L02 cells and antagonized the inhibitory effect of BDE-209 on the PI3K/AKT/GLUT4 pathway by counteracting the changes in the expression levels of p-IRS, AKT, PI3K, p-AKT, and GLUT4. Moreover, GW9662, a PPARγ inhibitor, blocked lipid accumulation and the upregulation of the mTOR/PPARγ/RXRα pathway in L02 cells induced by BDE-209 by relieving the increases in p-mTOR, PPARγ, and RXRα protein expression levels. In summary, this study revealed that BDE-209 disrupted glycolipid metabolism by inhibiting the PI3K/AKT/GLUT4 pathway and activating the mTOR/PPARγ/RXRα pathway.

Dietary Intake of Endocrine Disrupting Substances Presents in Environment and Their Impact on Thyroid Function

According to the available data, environmental pollution is a serious problem all over the world. Between 2015 and 2016, pollution was responsible for approximately nine million deaths worldwide. They also include endocrine disrupting chemicals (EDCs) that can interfere with the functioning of the thyroid gland. They are characterized by high persistence in the environment. These substances can enter the body through the gastrointestinal tract, respiratory system, as well as contact with the skin and overcome the placental barrier. EDC can be found in food, water, and personal care products. They can get into food from the environment and as a result of their migration to food products and cosmetics from packaging. EDCs can disrupt the functioning of the thyroid gland through a number of mechanisms, including disrupting the activation of thyroid receptors and the expression of genes that are related to the metabolism, synthesis, and transport of thyroid hormones (HT). There is a need to strengthen the food safety policy that aimed at the use of appropriate materials in direct contact with food. At the same time, an important action is to reduce the production of all waste and, when possible, use biodegradable packaging, which may contribute to the improvement of the quality of the entire ecosystem and the health of food, thus reducing the risk of developing thyroid diseases.