Differences in reproductive toxicity of TBBPA and TCBPA exposure in male Rana nigromaculata

TBBPA caused multiple intestinal injuries via ROS/NF-κB signal in common carp

Tetrabromobisphenol A (TBBPA) is an aquatic environment's prevalent pollutant, posing a great threat to the health of aquatic animals. The intestine is a key organ for nutrient absorption as well as an important barrier to prevent pollutants from invading the body of fish. Exploring the effects of pollutants on the intestine is of great significance for maintaining fish health. Therefore, the purpose of this study was to assess the toxic effects of TBBPA on the intestine of Cyprinus carpio L. (common carp) by establishing models of common carp and primary intestinal epithelial cells exposed to TBBPA. Histological observation revealed that TBBPA exposure led to damage in the intestinal mucosa and breakage of intestinal villi. Detection of oxidative stress levels showed that TBBPA increased the levels of ROS and MDA, and decreased the activity of SOD, CAT, GSH-PX, and T-AOC in intestinal tissue and cells. Observation of inflammatory factor levels revealed that TBBPA upregulated the mRNA levels of inflammatory factors (IL-6, TNF-α, IL-1β, NF-κB p65 and IκBα). ELISA and western blotting results were consistent with the mRNA results. Moreover, TBBPA induced cell death, as evidenced by TUNEL staining and flow cytometry and confirmed by increasing levels of Bax, Cas-3, Cyt C, RIP1, RIP3, and MLKL, together with decreasing the levels of Bcl-2. TBBPA also destroyed the intestinal tight junction by reducing the mRNA and protein levels of claudin-1, ZO-1, and occludin. In summary, this study reveals that TBBPA caused intestinal injuries, inducing oxidative stress, inflammation, cell death, and tight junction disruption via ROS/NF-κB signal in common carp.

Elucidation on the Interaction Between Transferrin and Tetrachlorobisphenol A Based on Multispectroscopic Analysis, Molecular Docking Technique, and Conformational Studies

Tetrachlorobisphenol A (TCBPA) is a kind of fire retardant extensively used in our life, but it can accumulate in organisms and potentially have toxic effects. Transferrin (TF) is a glycoprotein predominantly present in the blood plasma, serving as an essential mediator for the transportation of iron and other small molecules. In our study, various techniques including multi-spectroscopic and molecular docking were employed to examine the interaction between TCBPA and TF. The TF-TCBPA complex was formed with the binding constant (Ka) in 2.181 ± 0.035 × 104 M-1 at 298 K. ΔH and ΔS were all negative, which means dominant driving forces were van der Waals forces and H-bonds. The secondary structure of TF was changed by TCBPA, resulting in a decline in the α-helix structure, and a corresponding increase in the β-sheet structure. The molecular docking revealed that TCBPA was positioned within a pocket of TF, and it engaged in interactions with some amino acid residues through different forces. Importantly, the interaction between Tyr426/Asp392/His585 and TCBPA implies that TCBPA potentially interferes with the transportation of iron ions in vivo. All of above results indicated the adverse effects of TCBPA on the TF structure and activity should be more attention.

Molecular mechanisms of tetrabromobisphenol A (TBBPA) toxicity: Insights from various biological systems

Tetrabromobisphenol A (TBBPA) is a ubiquitous brominated flame retardant extensively incorporated into a wide range of products. As its utilization has escalated, its environmental exposure risks have concomitantly increased. The molecular properties of TBBPA allow it to persist in the environment and within organisms. In this review, we comprehensively examine the toxicity of TBBPA across different organ systems and elucidate the underlying molecular mechanisms. We particularly emphasize TBBPA's impact on biological signaling pathways, protein functionality, cellular architecture, and epigenetic regulation, which collectively lead to disruptions in endocrine, hepatic, neurological, reproductive, and other biological systems. The analysis of these toxicological phenomena and their fundamental molecular mechanisms has substantially enhanced our understanding of TBBPA's hazardous characteristics. This review also examines potential avenues for future research, with a focus on uncovering novel molecular mechanisms and assessing the toxicological impacts of TBBPA exposure, particularly in relation to interactions with other environmental contaminants. We propose a greater focus on examining the toxic effects and molecular mechanisms of long-term TBBPA exposure at environmentally relevant concentrations to facilitate more accurate assessments of human health risks.

Developmental exposures to common environmental pollutants result in long-term Reprogramming of hypothalamic-pituitary axis in mice

Humans are exposed to a range of endocrine disrupting chemicals (EDCs). Many studies demonstrate that exposures to EDCs during critical windows of development can permanently affect endocrine health outcomes. Most experimental studies address changes in secretion of hormones produced by gonads, thyroid gland and adrenals, and little is known about the ability of EDCs to produce long-term changes in the hypothalamic-pituitary (HP) control axes. Here, we examined the long-term effects of three common EDCs on male mouse HP gene expression, following developmental exposures. Pregnant mice were exposed to 0.2 mg/ml solutions of bisphenol S (BPS), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), or 3,3',5,5'-tetrabromobisphenol A (TBBPA) from pregnancy day 8 through lactation day 21 (weaning day). Male offspring were left untreated until postnatal day 140, where pituitaries and hypothalami were collected. Pituitaries were assed for gene expression via RNA sequencing, while specific genes were assessed for expression in hypothalami via RT-qPCR. Differential expression, as well as gene enrichment and pathway analysis, indicated that all three chemicals induced long-term changes, (mostly suppression) in pituitary genes involved in its endocrine function. BPS and BDE-47 produced effects overlapping significantly at the level of effected genes and pathways. All three chemicals altered pathways of gonad and liver HP axes, while BPS altered HP-adrenal and BDE-47 altered HP-thyroid pathways specifically. All three chemicals reduced expression of immune genes in the pituitaries. Targeted gene expression in the hypothalamus indicates down regulation of hypothalamic endocrine control genes by BPS and BDE-47 groups, concordant with changes in the pituitary, suggesting that these chemicals suppress overall HP endocrine function. Interestingly, all three chemicals altered pituitary genes of GPCR-mediated intracellular signaling molecules, key signalers common to many pituitary responses to hormones. The results of this study show that developmental exposures to common EDCs have long-term impacts on hormonal feedback control at the hypothalamic-pituitary level.

The Role of Placental DNA Methylation at Reproduction-Related Genes in Associations between Prenatal Bisphenol Analogues Exposure and the Digit Ratio in Children at Age 4: A Birth Cohort Study

Placental DNA methylation (DNAm) may be a potential mechanism underlying the effects of prenatal bisphenol analogues (BPs) exposure on reproductive health. Based on the Shanghai-Minhang Birth Cohort Study (S-MBCS), this study investigated associations of placental DNAm at reproduction-related genes with prenatal BPs exposure and children's digit ratios at age 4 using multiple linear regression models, and mediation analysis was further used to examine the mediating role of placental DNAm in the associations between prenatal BPs exposure and digit ratios among 345 mother-child pairs. Prenatal exposure to bisphenol A (BPA) was associated with hypermethylation at Protocadherin 8 (PCDH8), RBMX Like 2 (RBMXL2), and Sperm Acrosome Associated 1 (SPACA1), while bisphenol F (BPF) exposure was associated with higher methylation levels of Fibroblast Growth Factor 13 (FGF13). Consistent patterns were found in associations between higher DNAm at the 4 genes and increased digit ratios. Further mediation analysis showed that about 15% of the effect of BPF exposure on increased digit ratios was mediated by placental FGF13 methylation. In conclusion, the altered placental DNAm status might be a mediator underlying the feminizing effect of prenatal BPs exposure.

Tetrabromobisphenol A reduces male rats reproductive organ coefficients and disrupting sexual hormone by causing oxidative stress

Tetrabromobisphenol A (TBBPA) has become a topic of public attention due to its pervasive detection in the environment and organisms in recent decades. However, limited information is available regarding the toxicity of TBBPA on reproductive ability of male mammals. Herein, the reproductive toxicity of TBBPA was investigated in male rats to fill the knowledge gap. In this study, male rats were exposed to TBBPA (0, 10, 100, and 1000 mg/kg) for 6 weeks. Subsequently, body and organ indexes, histopathological evaluation of testis and epididymis, ultrastructural observation of sperm, testosterone and progesterone levels, and oxidative stress indicators were conducted to reveal corresponding mechanisms. Results obtained showed that compare to the control group, the body weight, testes weight, epididymis weight, seminal vesicle and coagulation glands weight of rats in the 1000 mg/kg group lost 8.30%, 16.84%, 20.16%, 19.72% and 26.42%, respectively. Intriguingly, exposure to TBBPA (10, 100, 100 mg/kg) resulted in substantial pathological damage in testis, epididymis and sperm. TBBPA exposure also increased malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents, as well as superoxide dismutase (T-SOD) and catalase (CAT) activities in testicular tissue. What's more, the testosterone and progesterone levels in male rat serum were significantly decreased after exposure to TBBPA for 6 weeks. Meanwhile, results of molecular docking showed that TBBPA has a strong affinity with estrogen receptors (ERs). These findings demonstrated that TBBPA exposure negatively impacts the reproductive ability of male rats, thus providing new insights for risk assessment for reproductive health under TBBPA exposure.

Development of a three-dimensional porous ionic liquid-chitosan-graphene oxide aerogel for efficient extraction and detection of polyhalogenated carbazoles in sediment samples

The three-dimensional porous ionic liquid-chitosan-graphene oxide aerogel (IL-CS-GOA) monolithic adsorbent with a through-hole structure was prepared using natural chitosan (CS) as the skeletal framework, graphene oxide (GO) as the support to provide mechanical strength, and ionic liquid (IL) as the porogen and modifier. The resulting IL-CS-GOA demonstrated a fluffy and porous structure with various pore sizes and excellent regeneration capability (over six cycles). Its specific surface area exceeded that of CS-GOA and IL-GOA by more than 7 times, enhancing its polyhalogenated carbazoles (PHCZs) adsorption capacity. Within 5 min, IL-CS-GOA (1.0 mg) exhibited adsorption amounts of 539 ng mg-1 for 3-bromocarbazole (3-BCZ), 716 ng mg-1 for 2,7-dibromocarbazole (2,7-BCZ), and 798 ng mg-1 for 1,3,6,8-tetrabromocarbazole (1,3,6,8-BCZ), showcasing its rapid mass transfer and high adsorption capabilities. IL-CS-GOA was utilized as the adsorbent for glass dropper extraction (GDE) in conjunction with gas chromatography-mass spectrometry (GC-MS/MS), to develop a highly efficient and accurate method for determining PHCZs in sediments. Under optimal conditions, the established method exhibited a wide linear range (0.4-250 ng g-1, r ≥ 0.9990), low detection limits (0.04-0.24 ng g-1), and satisfactory recoveries (80.5 %-93.8 %), enabling the accurate and rapid detection of PHCZs in sediment samples. This study presents a novel approach for creating three-dimensional porous aerogels, introduces a new form of sample pretreatment using GDE with a monolithic adsorbent, and offers a new method for the determination of PHCZs in environmental matrices.

A prioritization strategy for functional alternatives to bisphenol A in food contact materials

The use of bisphenol A (BPA), a substance of very high concern, is proposed to be banned in food contact materials (FCMs) in the European Union. To prevent regrettable substitution of BPA by alternatives with similar or unknown hazardous properties, it is of importance to gain the relevant toxicological information on potential BPA alternative substances and monitor them adequately. We created an inventory of over 300 substances mentioned as potential BPA alternatives in regulatory reports and scientific literature. This study presents a prioritization strategy to identify substances that may be used as an alternative to BPA in FCMs. We prioritized 20 potential BPA alternatives of which 10 are less familiar. We subsequently reviewed the available information on the 10 prioritized less familiar substances regarding hazard profiles and migration potential obtained from scientific literature and in silico screening tools to identify a possible risk of the substances. Major data gaps regarding the hazard profiles of the prioritized substances exist, although the scarce available data give some indications on the possible hazard for some of the substances (like bisphenol TMC, 4,4-dihydroxybenzophenone, and tetrachlorobisphenol A). In addition, very little is known about the actual use and exposure to these substances. More toxicological research and monitoring of these substances in FCMs are, therefore, required to avoid regrettable substitution of BPA in FCM.

Flame retardant tetrabromobisphenol A (TBBPA) disrupts histone acetylation during zebrafish maternal-to-zygotic transition

3,3',5.5'-Tetrabromobisphenol A (TBBPA) is a widely used brominated flame-retardant utilized in the production of electronic devices and plastic paints. The objective of this study is to use zebrafish as a model and determine the effects of TBBPA exposure on early embryogenesis. We initiated TBBPA exposures (0, 10, 20 and 40μM) at 0.75 h post fertilization (hpf) and monitored early developmental events such as cleavage, blastula and epiboly that encompass maternal-to-zygotic transition (MZT) and zygotic genome activation (ZGA). Our data revealed that TBBPA exposures induced onset of developmental delays by 3 hpf (blastula). By 5.5 hpf (epiboly), TBBPA-exposed (10-20 μM) embryos showed concentration-dependent developmental lag by up to 3 stages or 100% mortality at 40 μM. Embryos exposed to sublethal TBBPA concentrations from 0.75-6 hpf and raised in clean water to 120 hpf showed altered larval photomotor response (LPR), suggesting a compromised developmental health. To examine the genetic basis of TBBPA-induced delays, we conducted mRNA-sequencing on embryos exposed to 0 or 40 μM TBBPA from 0.75 hpf to 2, 3.5 or 4.5 hpf. Read count data showed that while TBBPA exposures had no overall impacts on maternal or maternal-zygotic genes, collective read counts for zygotically activated genes were lower in TBBPA treatment at 4.5 hpf compared to time-matched controls, suggesting that TBBPA delays ZGA. Gene ontology assessments for both time- and stage-matched differentially expressed genes revealed TBBPA-induced inhibition of chromatin assembly- a process regulated by histone modifications. Since acetylation is the primary histone modification system operant during early ZGA, we immunostained embryos with an H3K27Ac antibody and demonstrated reduced acetylation in TBBPA-exposed embryos. Leveraging in silico molecular docking studies and in vitro assays, we also showed that TBBPA potentially binds to P300- a protein that catalyzes acetylation- and inhibits P300 activity. Finally, we co-exposed embryos to 20 μM TBBPA and 50 μM n-(4-chloro-3-trifluoromethyl-phenyl)-2-ethoxy-6-pentadecyl-benzamide (CTPB) -a histone acetyltransferase activator that promotes histone acetylation- and showed that TBBPA-CTPB co or pre-exposures significantly reversed TBBPA-only developmental delays, suggesting that TBBPA-induced phenotypes are indeed driven by repression of histone acetylation. Collectively, our work demonstrates that TBBPA disrupts ZGA and early developmental morphology, potentially by inhibiting histone acetylation. Future studies will focus on mechanisms of TBBPA-induced chromatin modifications.

Exposure to TCBPA stimulates the growth of arterial smooth muscle cells through the activation of the ROS/NF-κB/NLRP3 signaling pathway

Tetrachlorobisphenol A (TCBPA) and Tetrabromobisphenol S (TBBPS) are organic compounds widely used in industrial production, including in plastic and textile manufacturing. Presently, residual TCBPA is commonly detected in the environment as well as in human and animal sera. Therefore, it is imperative to assess the potential toxicological effects of TCBPA on organismal health. A series of biochemical experiments, including indirect immunofluorescence, ELISA, Western blot, MTT, etc, were conducted to analyze the effects of TCBPA on vascular smooth muscle cells. In this study, the biological impact of TCBPA on arterial smooth muscle cells (ASMCs) was investigated. CCK8 and EdU assays demonstrated significant proliferation of ASMCs following TCBPA treatment. Furthermore, TCBPA induced an inflammatory response in smooth muscle cells, as evidenced by the upregulated expression of inflammatory cytokines including IL-6, IL-1β, and MCP1. Additionally, we observed that TCBPA triggered an oxidative stress response in ASMCs by measuring ROS levels. To elucidate the underlying molecular mechanism of TCBPA-induced ASMC proliferation, we found that NLRP3 was essential for this process. Further investigation revealed that NLRP3 activation was mediated by NF-κB (which was activated by ROS). In summary, our findings suggest that TCBPA promotes the proliferation of ASMCs through the ROS/NF-κB/NLRP3 signaling cascade. This work indicates that TCBPA may represent a potential risk factor for the development of atherosclerosis, highlighting the need for judicious control of TCBPA usage.

Chronic neurotoxicity of Tetrabromobisphenol A: Induction of oxidative stress and damage to neurons in Caenorhabditis elegans

Tetrachlorobisphenol A (TCBPA) has been used as an alternative flame retardant in various fields. However, the long-term effects of TCBPA on the nervous system remain unclear. Thus, Caenorhabditis elegans (L4 larvae) were selected as a model animal to investigate the neurotoxic effects and underlying mechanisms after 10 d of TCBPA exposure. Exposure to TCBPA (0.01-100 μg/L) decreased locomotive behavior in a concentration-dependent manner. In addition, reactive oxygen species (ROS) formation and lipofuscin accumulation were significantly increased, and the expression of sod-3 was upregulated in the exposed nematodes, indicating that TCBPA exposure induced oxidative damage. Furthermore, 100 μg/L TCBPA exposure caused a reduction in dopamine and serotonin levels, and damage in dopaminergic and serotoninergic neurons, which was further confirmed by the downregulated expression of related genes (e.g., dop-1, dop-3, cat-1, and mod-1). Molecular docking analysis demonstrated the potential of TCBPA to bind to the neurotransmitter receptor proteins DOP-1, DOP-3, and MOD-1. These results indicate that chronic exposure to TCBPA induces neurotoxic effects on locomotive behavior, which is associated with oxidative stress and damage to dopaminergic and serotoninergic neurons.

Environmentally relevant exposure to tetrabromobisphenol A induces reproductive toxicity via regulating glucose-6-phosphate 1-dehydrogenase and sperm activation in Caenorhabditis elegans

Tetrabromobisphenol A (TBBPA), a ubiquitous brominated flame-retardant environmental pollutant, has been reported to cause reproductive toxicity by chronic exposure. However, the acute reproductive risk and mechanisms of TBBPA toxicity to individuals, especially at environmentally relevant levels, remains a topic of debate. In this study, Caenorhabditis elegans was used to investigate the reproductive toxicity of acute exposure to TBBPA at environmentally relevant doses. The reproductive end points (embryonic lethality ratio and brood size), oxidative stress, sperm activation, and molecular docking were evaluated. Results showed that, after 24 h of TBBPA treatment, even at the lowest concentration (1 μg/L), the embryonic lethality ratio of C. elegans increased significantly, from 1.63 % to 3.03 %. Furthermore, TBBPA induced oxidative stress with significantly increased expression of sod-3 in C. elegans, which further raised the level of reproductive toxicity through inhibiting the activation of sperm in nematodes. In addition, molecular docking suggested TBBPA might compete for the glucose-6-phosphate-binding site of glucose-6-phosphate 1-dehydrogenase, resulting in oxidative stress generation. Accordingly, our findings indicate that even acute exposure to environmental concentrations of TBBPA may induce reproductive toxicity through reducing sperm activation in nematodes.

Toxicological evaluation of TBBPA by common carp (Cyprinus carpio) about the in vivo/vitro disturbance of the AHR pathway

Tetrabromobisphenol A (TBBPA) is a widely used plastic additive with high bioaccumulation potential and toxicity on both humans and wildlife. Currently, research on its ecotoxicity and the underlying mechanism is limited. Using common carp (Cyprinus carpio), we evaluated the toxicity of TBBPA, especially focusing on its alteration of a key metabolism-related pathway aryl hydrocarbon receptor (AHR), using in vivo/vitro assays and in silico simulation. The 96 h LC50 of TBBPA of common carp was 4.2 mg/L and belonged to the acute toxic level II. The bioaccumulation potential of TBBPA follows the role of liver > gill > brain and varies between 3- and 14-day exposure. On the AHR pathway respect, as expected, the metabolism-related cyp1a1 and cyp1b1 were upregulated in the liver and brain. Ahr2, the receptor, was also upregulated in the brain under TBBPA exposure. The alteration of gene expression was tissue-specific while the difference between 3- or 14-day exposure was minor. AHR inhibition assay indicated the 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD)-induced AHR transactivation can be inhibited by TBBPA suggesting it is not a potent agonist but a competitive antagonist. In silico analysis indicated TBBPA can be successfully docked into the binding cavity with similar poses but still have AHR-form-specific interactions. Molecular dynamics simulation proved TBBPA can be more flexible than the coplanar ligand TCDD, especially in ccaAHR1b with greater root-mean-square deviation (RMSD), of which TCDD-induced transactivation seemed not to be blocked by TBBPA. This research increased the understanding of TBBPA toxicity and alteration of the AHR pathway, and pointed out the need to perform additional toxicology evaluation of emerging contaminants, especially on non-model species.

Tetrabromobisphenol a and its alternative tetrachlorobisphenol a induce oxidative stress, lipometabolism disturbance, and autophagy in the liver of male Pelophylax nigromaculatus

Tetrabromobisphenol A (TBBPA) and tetrachlorobisphenol A (TCBPA) have been widely used as flame retardants. However, their potential health risks to organisms have raised concerns, particularly for liver toxicity. Present study aimed to explore the toxic effects of TCBPA and TBBPA on black-spotted frogs (Pelophylax nigromaculatus) liver oxidative stress, autophagy, and lipid accumulation. After exposure to 0.001, 0.01, 0.1, and 1 mg/L TBBPA and TCBPA for 14 days, the content of cholesterol and triglyceride were significantly elevated. In addition, the malondialdehyde level rose greatly in dose dependent. However, the glutathione level declined in high TBBPA groups (0.01 and 0.1 mg/L). Furthermore, expressions of Beclin1, Atg5, and Atg7 were significantly increased, while p62 was markedly declined, respectively. Results obstained suggested that TBBPA and TCBPA exposure induced liver toxicity in black-spotted frog. This study provided insights into the toxicity mechanism of bisphenol flame retardants in amphibians and will aid in the ecological risk assessment of flame retardants.

The bioaccumulation and biotransformation of tetrabromobisphenol A bis (allyl ether) in common carp (Cyprinus carpio)

Tetrabromobisphenol A bis (allyl ether) (TBBPA-BAE) is an extensively used brominated flame retardant, which has raised considerable concern because of its neurotoxic and endocrine disruption effects on aquatic organisms. However, previous studies mainly focused on the parent compound before modification, tetrabromobisphenol A (TBBPA), and little information is available about the bioconcentration and biotransformation of TBBPA derivatives in fish. In this study, we investigated the tissue-specific uptake, elimination kinetic, and biotransformation of TBBPA-BAE in common carp (Cyprinus carpio). The fish were exposed to TBBPA-BAE at environmentally relevant concentrations (20 μg·L-1) for 28 days, followed by 14 days of depuration. The results showed TBBPA-BAE could rapidly accumulate in common carp. Among the seven tissues studied, the highest concentrations of TBBPA-BAE were observed in the liver (6.00 μg·g-1 wet weight [ww]) on day 24, while the longest residence time was observed in the kidney (t1/2 values of 18.7 days). Biotransformation of TBBPA-BAE was documented in the in vivo experiments, and 14 different phase I and phase II metabolites were identified in the liver. These findings suggest the biotransformation products of TBBPA-BAE should be considered for a comprehensive risk evaluation.

Association between Urinary BPA Substitutes and Precocious Puberty among Girls: A Single-Exposure and Mixed Exposure Approach from a Chinese Case-Control Study

There is an argument that BPA substitutes may have the same or more deleterious health effects as BPA due to their structural similarity. This study explored the association between urinary BPA substitutes and precocious puberty among girls by including 120 girls with precocious puberty (cases) aged 2-10 years enrolled at Nanjing Children's Hospital Department of Endocrinology in China between April 2021 to September 2021 and 145 healthy girls (controls) recruited from a primary school. Logistic regression was used to evaluate the effect of single exposures, and Bayesian kernel machine regression (BKMR) and quantile-based g-computation were used for the mixed effect. In the multivariate logistic regression, BPS (bisphenol S), TBBPA (tetrabromobisphenol A), and BPFL (bisphenol-FL) were significantly associated with increased risk of precocious puberty (odds ratio (OR) = 1.75, 95% confidence interval (CI): 1.13, 2.76, p = 0.014), (OR = 1.46, CI: 1.06, 2.05; p = 0.023), and (OR = 1.47, CI: 1.01, 2.18; p = 0.047), respectively. The BMKR and quantile-based g-computation models revealed consistent associations for single exposures and there was insufficient evidence for the associations of the mixed exposure of bisphenols with precocious puberty. In conclusion, BPA substitutes such as BPS, TBBPA, and BPFL may be associated with an increased risk of precocious puberty in girls.

Developmental toxicity of TCBPA on the nervous and cardiovascular systems of zebrafish (Danio rerio): A combination of transcriptomic and metabolomics

Tetrachlorobisphenol A (TCBPA), a widely used halogenated flame retardant, is frequently detected in environmental compartments and human samples. However, unknown developmental toxicity and mechanisms limit the entire understanding of its effects. In this study, zebrafish (Danio rerio) embryos were exposed to various concentrations of TCBPA while a combination of transcriptomics, behavioral and biochemical analyzes as well as metabolomics were applied to decipher its toxic effects and the potential mechanisms. We found that TCBPA could interfere with nervous and cardiovascular development through focal adhesion and extracellular matrix-receptor (ECM-receptor) interaction pathways through transcriptomic analysis. Behavioral and biochemical analysis results indicated abnormal swimming behavior of zebrafish larvae. Morphological observations revealed that TCBPA could cause the loss of head blood vessels. Metabolomic analysis showed that arginine-related metabolic pathways were one of the main pathways leading to TCBPA developmental toxicity. Our study demonstrated that by using omics, TCBPA was shown to have neurological and cardiovascular developmental toxicity and the underlying mechanisms were uncovered and major pathways identified.

Thin-layer chromatography coupled with HPLC-DAD/UHPLC-HRMS for target and non-target determination of emerging halogenated organic contaminants in animal-derived foods

In this study, a simple, solvent-saving, and sensitive method was established using high-performance liquid chromatography coupled with high-resolution mass spectrometry to quantitively determine 16 emerging halogenated organic contaminants (HOCs), including polyhalogenated carbazoles, halogenated phenols, and tetrabromobisphenol-A analogs, and to qualitatively identify non-target HOCs in animal-derived food samples. The sample extracts were physically frozen to remove most lipids and further purified by thin-layer chromatography according to the targets polarity. The method detection limit and method quantification limit of 16 HOCs were in the range of 0.003-9.168 and 0.010-30.601 ng·g-1 dry weight, respectively. The recoveries were within 69.1-111.0 %, the intra/inter-day precisions were 0.1-6.1 % and 0.1-6.7 %, and the matrix effects were between -12.1 and 10.8 %, all within the acceptable range. Finally, 16 HOCs were detected in nine actual samples in range of not detected-307.22 ng·g-1 dry weight. Moreover, five bromides and two chlorides were identified by using non-target analysis in animal-derived foods.

A Review on Tetrabromobisphenol A: Human Biomonitoring, Toxicity, Detection and Treatment in the Environment

Tetrabromobisphenol A (TBBPA) is a known endocrine disruptor employed in a range of consumer products and has been predominantly found in different environments through industrial processes and in human samples. In this review, we aimed to summarize published scientific evidence on human biomonitoring, toxic effects and mode of action of TBBPA in humans. Interestingly, an overview of various pretreatment methods, emerging detection methods, and treatment methods was elucidated. Studies on exposure routes in humans, a combination of detection methods, adsorbent-based treatments and degradation of TBBPA are in the preliminary phase and have several limitations. Therefore, in-depth studies on these subjects should be considered to enhance the accurate body load of non-invasive matrix, external exposure levels, optimal design of combined detection techniques, and degrading technology of TBBPA. Overall, this review will improve the scientific comprehension of TBBPA in humans as well as the environment, and the breakthrough for treating waste products containing TBBPA.

Transcriptomic profiling reveals the neuroendocrine-disrupting effect and toxicity mechanism of TBBPA-DHEE exposure in zebrafish (Danio rerio) during sexual development

TBBPA bis(2-hydroxyethyl) ether (TBBPA-DHEE) pollution in the environment has raised serious public health concerns due to its potential neuroendocrine-disrupting effects. The neuroendocrine-disrupting effects of TBBPA-DHEE on marine spices, on the other hand, have received little attention. The behavioral, neuroendocrine-disrupting, and possible reproductive toxicity of TBBPA-DHEE were assessed in sexual developing zebrafish treated for 40 days by examining locomotor activity, Gonadotrophin releasing hormone (GnRH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) levels, and quantifying gene expression. In addition, transcriptome profiling was carried out to explore the possible mechanisms. According to our findings, TBBPA-DHEE treated zebrafish showed altered locomotor activity, a potential neuroendocrine-disrupting effect via the toxic effect on the hypothalamus and pituitary gland, which is evident in decreased levels of GnRH, FSH, and LH, according to our findings. The transcriptomic profiling reveals that a total of 216 DEGs were detected (5 upregulated and 211 down-regulated). Transcriptomic analysis shows that TBBPA-DHEE exposure caused decreased transcript levels of genes (cyp11a1, ccna1, ccnb2, ccnb1, cpeb1b, wee2) involved in cell cycle oocyte meiosis, progesterone mediated oocyte maturation, and ovarian steroidogenesis, which are known reproduction-related pathways. Overall, these findings add to our understanding of the impact of TBBPA-DHEE and biomonitoring in the maritime environment.

A transcriptomic-based analysis predicts the neuroendocrine disrupting effect on adult male and female zebrafish (Danio rerio) following long-term exposure to tetrabromobisphenol A bis(2-hydroxyethyl) ether

Endocrine-disrupting chemicals (EDCs) are now ubiquitously distributed in the environment. Tetrabromobisphenol A bis(2-hydroxyethyl) ether (TBBPA-DHEE) pollution in environment media poses a significant threat to humans and aquatic organisms as a result of its potential neurotoxicity and endocrine-disrupting effect. The endocrine-disrupting effects of TBBPA-DHEE on aquatic organisms, however, have received limited attention. In this study, the neurotoxicity and reproductive endocrine-disruptive effect of TBBPA-DHEE was evaluated by observing the neurobehavioral changes, vitellogenin (VTG), testosterone, 17β-estradiol and gene expression levels in adult male and female zebrafish exposed to TBBPA-DHEE (0.05, 0.2 and 0.3 mg/L) for 100 days. Furthermore, transcriptomic analysis was conducted to unravel other potential neuroendocrine-disrupting mechanism. Our result showed TBBPA-DHEE significantly (p < 0.05) altered the locomotor behavior and motor coordination abilities in both sexes. Steroid hormone and VTG levels were also altered indicating the neuroendocrine-disrupting effect of TBBPA-DHEE on the hypothalamic-pituitary-gonadal-axis. A total of 1568 genes were upregulated and 542 genes downregulated in males, whereas, 1265 upregulated and 535 downregulated genes were observed in females. The KEGG enrichment analysis showed that cell cycle and p55 signaling pathways were significantly enriched due to TBBPA-DHEE exposure. These pathways and its component genes are potential target of EDCs. The significant upregulation of genes in these pathways could partly explain the neuroendocrine disrupting effect of TBBPA-DHEE. The observed toxic effects of TBBPA-DHEE observed in this study is confirmation of the endocrine-disrupting toxicity of this chemical which would be valuable in biosafety evaluation and biomonitoring of TBBPA-DHEE for public health purposes.

An iron-based metal-organic framework as a novel dispersive solid-phase extraction sorbent for the efficient adsorption of tetrabromobisphenol A from environmental water samples

For environmental safety, it is important to establish a simple, rapid, and sensitive method for emerging pollutants. Here, a dispersive solid-phase extraction (d-SPE) method based on an iron-based metal-organic framework (Fe-MIL-88-NH₂) combined with high-performance liquid chromatography (HPLC) was developed for tetrabromobisphenol A (TBBPA) in water samples. Fe-MIL-88-NH₂ was synthesized using a solvothermal method and completely characterized. Fe-MIL-88-NH₂ had good water stability and gave a maximum adsorption capacity of 40.97 mg g^-1 for TBBPA. The adsorption of TBBPA on Fe-MIL-88-NH₂ followed Langmuir adsorption models and a pseudo-second-order kinetic model. The bromine ion and the hydroxyl group of TBBPA could form strong hydrogen bond interactions with the amino protons around the cavity of Fe-MIL-88-NH₂, which was in accord with the molecular simulation calculations. Furthermore, several important d-SPE parameters were optimized, such as the amount of materials, extraction time, pH, ionic strength, elution solvent type, and volume. The established method showed good linearity in the concentration range of 0.005-100 μg g^-1 (r² ≥ 0.9996). This method's limits of detection (LOD) and quantification (LOQ) were 0.001 μg g^-1 and 0.005 μg g^-1, respectively. The recoveries in spiked water samples ranged from 87.5% to 104.9%. The proposed method was applied successfully to detect TBBPA in environmental water samples.

Time- and dose-dependent detoxification and reproductive endocrine disruption induced by tetrabromobisphenol A (TBBPA) in mussel Mytilus galloprovincialis

As a typical brominated flame retardant (BFR), tetrabromobisphenol A (TBBPA) has been frequently detected in both biotic and abiotic matrices in marine environment. Our previous study found that genes related to metabolism phase I/II/III as well as steroid metabolism in Mytilus galloprovincialis were significantly altered by TBBPA treatment. However, the time- and dose-dependent response profiles of these genes to TBBPA exposure were rarely reported. In this study, the time- and dose-dependent effects of TBBPA on detoxification and reproductive endocrine disruption in M. galloprovincialis were explored by evaluating the responses of related gene expressions, enzymatic activities and gametogenesis to different concentrations of TBBPA (0.6, 3, 15, 75 and 375 μg/L) for different durations (14, 21 and 28 days). The results showed that the TBBPA accumulation increased linearly with the increases of exposure time and dose. Cytochrome P450 family 3 (CYP3A1-like) cooperated with CYP4Y1 for phase I biotransformation of TBBPA in mussels. The dose-response curves of phase II/III genes (glutathione-S-transferase (GST), P-glycoprotein (ABCB), and multidrug resistance protein (ABCC)) showed similar response profiles to TBBPA exposure. The common induction of phase I/II/III (CYPs, GST, ABCB and ABCC) suggested TBBPA detoxification regulation in mussels probably occurred in a step-wise manner. Concurrently, direct sulfation mediated by sulfotransferases (SULTs) on TBBPA was also the vital metabolic mechanism for TBBPA detoxification, which was supported by the coincidence between up-regulation of SULT1B1 and TBBPA accumulation. The significant promotion of steroid sulfatase (STS) might result from TBBPA-sulfate catalyzed by SULT1B1 due to its chemical similarity to estrone-sulfate. Furthermore, the promotion of gametogenesis was consistent with the induction of STS, suggesting that STS might interrupt steroids hydrolysis process and was responsible for reproductive endocrine disruption in M. galloprovincialis. This study provides a better understanding of the detoxification and endocrine-disrupting mechanisms of TBBPA.

Quantitative SERS Detection of TBBPA in Electronic Plastic Based on Hydrophobic Cu-Ag Chips

Tetrabromobisphenol A (TBBPA) was one of the most widely used brominated flame retardants. However, it easily contaminates nature and harms the environment and human health during its production and use. Therefore, it is necessary to strictly control the content of TBBPA in electronics. Surface-enhanced Raman spectroscopy has the advantages of being fast and sensitive, but it is difficult to obtain the SERS spectra of TBBPA because the hydrophobic TBBPA molecule is difficult to approach with the hydrophilic surface of common noble metal SERS substrates. In the present work, a hydrophobic Cu-Ag chip was developed for the SERS detection of TBBPA. The integration of the hydrophobic interaction and the Ag-Br bonding promoted the adsorption of TBBPA on the Cu-Ag chip, allowing for SERS detection. It was observed that both the hydrophobicity and bimetallic composition of the Cu-Ag chip played important roles in the SERS detection of TBBPA. Under the optimized conditions, the low limit of detection of the established SERS method for TBBPA was 0.01 mg L^-1, within a linear range of 0.1-10 mg L^-1. Combined with ultrasonic-assisted extraction, the substrate could be used for the quantitative determination of TBBPA in electronic products. Compared with the HPLC-UV method used as a national standard, the relative error of the SERS method for quantifying the TBBPA content in a mouse cable and shell was ±3% and ±7.7%, respectively. According to the SERS results, the recovery of TBBPA in the spiked mouse shell was 95.6%.

Per- and Polyfluoroalkyl Substances (PFASs) Impair Lipid Metabolism in Rana nigromaculata: A Field Investigation and Laboratory Study

Per- and polyfluoroalkyl substances (PFASs) are ubiquitous environmental pollutants, causing environmental threats and public health concerns, but information regarding PFAS hepatotoxicity remains elusive. We investigated the effects of PFASs on lipid metabolism in black-spotted frogs through a combined field and laboratory study. In a fluorochemical industrial area, PFASs seriously accumulate in frog tissues. PFAS levels in frog liver tissues are positively related to the hepatosomatic index along with triglyceride (TG) and cholesterol (TC) contents. In the laboratory, frogs were exposed to 1 and 10 μg/L PFASs, respectively (including PFOA, PFOS, and 6:2 Cl-PFESA). At 10 μg/L, PFASs change the hepatic fatty acid composition and significantly increase the hepatic TG content by 1.33 to 1.87 times. PFASs induce cross-talk accumulation of TG, TC, and their metabolites between the liver and serum. PFASs can bind to LXRα and PPARα proteins, further upregulate downstream lipogenesis-related gene expression, and downregulate lipolysis-related gene expression. Furthermore, lipid accumulation induced by PFASs is alleviated by PPARα and LXRα antagonists, suggesting the vital role of PPARα and LXRα in PFAS-induced lipid metabolism disorders. This work first reveals the disruption of PFASs on hepatic lipid homeostasis and provides novel insights into the occurrence and environmental risk of PFASs in amphibians.

The antagonistic effect of melatonin on TBBPA-induced apoptosis and necroptosis via PTEN/PI3K/AKT signaling pathway in swine testis cells

Tetrabromobisphenol A (TBBPA) is a widely used industrial brominated flame retardant, which can endanger animal and human health, including cytotoxicity, endocrine disruption, reproductive toxicity and so on. Melatonin (MT) is a noteworthy free radical scavenger and an antioxidant to alleviate oxidative stress. To investigate the cytotoxic of TBBPA on swine testis cells (ST cells), as well as the antagonistic effect of MT, we established TBBPA exposure and MT antagonistic models, used flow cytometry and AO/EB staining methods to detect apoptosis and necroptosis, used DCFH-DA method to examine the content of reactive oxygen species (ROS) and investigated the expression of associated genes using RT-PCR and Western blot. According to our findings, TBBPA exposure induced cell death in ST cells. TBBPA increased ROS levels, thus increasing PTEN expression and decreasing PI3K and AKT expression. Apoptosis-related factors (Caspase-3, Bax, Cyt-c, and Caspase-9) and necroptosis-related factors (RIPK1, RIPK3, and MLKL) were considerably elevated, in addition to the reduced expression of BCL-2 and Caspase-8. We also found that MT inhibited apoptosis and necroptosis in TBBPA-induced ST cells and effectively resolved the abnormal expression of related signaling pathways. In summary, the above results indicate that MT alleviates the disorder of PTEN/PI3K/AKT signaling pathway via inhibiting ROS overproduction, thereby mitigating apoptosis and necroptosis caused by TBBPA. This research provides a theoretical basis for further understanding of the toxicity of TBBPA and the detoxification of MT against environmental toxics.

Tetrachlorobisphenol A mediates reproductive toxicity in Caenorhabditis elegans via DNA damage-induced apoptosis

Tetrachlorobisphenol A (TCBPA), an alternative to tetrabromobisphenol A (TBBPA), is ubiquitous in the environment and could potentially impact the reproductive system of organisms. However, the mechanisms underlying TCBPA-mediated reproductive effects remain unclear. Herein, we exposed Caenorhabditis elegans (C. elegans, L4 larvae) to TCBPA at environmentally relevant doses (0-100 μg/L) for 24 h. Exposure to TCBPA at concentrations of 1-100 μg/L impaired fertility of C. elegans, as indicated by brood size. After staining, the number of germline cells decreased in a dose-dependent manner, whereas germline cell corpses increased in exposed nematodes (10-100 μg/L TCBPA). Moreover, the expression of genes related to the germline apoptosis pathway was regulated following exposure to 100 μg/L TCBPA, indicating the potential role of DNA damage in TCBPA-induced apoptosis. Apoptosis was nearly abolished in ced-4 and ced-3 mutants and blocked in hus-1, egl-1, cep-1, and ced-9 mutants. Numerous foci were detected in TCBPA (100 μg/L)-exposed hus-1::GFP strains. These results indicate that TCBPA induces hus-1-mediated DNA damage and further causes apoptosis via a cep-1-dependent pathway. Our data provide evidence that TCBPA causes reproductive toxicity via DNA damage-induced apoptosis.

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.

Testicular Toxicity of Chloroxylenol in Rats: Biochemical, Pathological and Flow Cytometric Study

Background

Chloroxylenol (para-chloro-meta-xylenol, PCMX) is claimed to be highly harmful both to humans and the environment. Toxic effects of PCMX on testicular functions are scarcely discussed in the literature.

Aim of Study

To study testicular toxic effects of PCMX on male Sprague-Dawley rats.

Materials and Methods

Forty animals were randomly distributed into three groups: negative control (G I), vehicle group (G II) and PCMX group (G III). PCMX group was subdivided into three subgroups: GIIIa: received PCMX 100 mg/kg, GIIIb: received PCMX 200 mg/kg and G IIIc: received PCMX 500 mg/kg. Hormonal assay included assessment of serum testosterone and estradiol levels. Histopathological examination of testicular tissue, analysis of cellular viability, necrosis and apoptosis in testicular tissue by flow cytometry, analysis of cellular DNA content and phases of cell cycle analysis by flow cytometry were also performed.

Results

Rats in the groups exposed to PCMX (G IIIa, G IIIb and G IIIc) had significantly lower estradiol and testosterone levels in comparison to control groups (G I and GII). Histopathological examination of testicular tissue of PCMX-exposed rats showed irregular crossly sectioned seminiferous tubules with their lumina containing scanty spermatids and spermatozoa. G IIIc animals showed eosinophilic proteinaceous material and vacuolated and necrotic interstitial cells of Leydig. Rats in PCMX-exposed groups (G IIIa, G IIIb and G IIIc) showed significantly lower testicular tissue viability in comparison to control groups (G I and G II). Rats in PCMX-exposed groups (G IIIa, G IIIb and G IIIc) showed significantly lower percentage of cells in the G0/G1 phase in comparison to control groups (G I and G II).

Conclusion

Rats exposed to PCMX had significant reduction in testosterone and estradiol levels with marked histopathological alterations affecting testicular tissues. These effects are dose-dependent.

Dissolved organic matter heightens the toxicity of tetrabromobisphenol A to aquatic organisms

Tetrabromobisphenol A (TBBPA) is a new type of persistent organic pollutant, which causes environmental pollution and health problems, and has attracted the attention of the international research community. Once released into the environment, TBBPA can interact with dissolved organic matter (DOM), which affects its behavior. However, the effect of DOM on the biological toxicity of TBBPA remains unclear. The toxic effects of TBBPA on three model aquatic organisms (Chlorella pyrenoidosa, Daphnia magna, and Danio rerio), in the absence and presence of DOM were investigated. The order of acute toxicity of TBBPA to the three aquatic organisms was D. magna > D. rerio > C. pyrenoidosa. In the presence of DOM the median effect/lethal concentrations values of TBBPA to the three aquatic organisms decreased by at least 32 (C. pyrenoidosa), 52 (D. magna), and 6.6% (D. rerio), implying that DOM enhanced the acute toxicity of TBBPA to all the organisms. Moreover, the higher the concentration of DOM, the higher the acute toxicity of TBBPA. Furthermore, the presence of DOM increased total reactive oxygen species (ROS) induced by TBBPA in a concentration-dependent manner. A tracking analysis of total ROS in the three aquatic organisms also showed that the presence of DOM aggravated the accumulation of total ROS induced by TBBPA, indicating that oxidative stress is a characteristic mechanism of toxicity of TBBPA to aquatic organisms when DOM is present. In addition, the evaluated risk quotient indicated that the ecological risk of TBBPA to aquatic organisms can increase in environments rich in DOM.

TBBPA and its alternative TCBPA induced ROS-dependent mitochondria-mediated apoptosis in the liver of Rana nigromaculata

Tetrabromobisphenol A (TBBPA), which is the most widely employed brominated flame retardant, and its alternative tetrachlorobisphenol A (TCBPA) are widely distributed in aquatic environments. In the present study, the hepatotoxicity induced by TBBPA and TCBPA was investigated in Rana nigromaculata, and the potential mechanisms were investigated with a particular focus on ROS (reactive oxygen species) -dependent mitochondria-mediated apoptosis. Healthy adult frogs were exposed to 0, 0.001, 0.01, 0.1, and 1 mg/L waterborne TBBPA and TCBPA for 14 days. The results showed that liver weight was significantly increased by 51.52%-98.99% in the 0.01, 0.1, and 1 mg/L TBBPA and TCBPA groups relative to the control. Histological examination revealed that the structure of the liver, to some extent, was influenced by TBBPA and TCBPA with nuclear shrinkage and mitochondrial swelling. Meanwhile, TBBPA and TCBPA have significantly increased the alanine transaminase level in serum and the content of ROS, while inhibiting the activity of superoxide dismutase in the liver. In addition, DNA fragments were observed in the TBBPA and TCBPA groups relative to the control. Expression of Cytochrome C was significantly increased by 1.13-, 1.38-, 1.60-, and 2.46-fold in 0.001, 0.01, 0.1, and 1 mg/L TBBPA, and by 1.26-, 1.51-, 2.14-, and 2.98- fold in 0.001, 0.01, 0.1, and 1 mg/L TCBPA, respectively, which indicated that TCBPA may be more toxic than TBBPA. Similarly, the ratio of Bax/Bcl-2 was increased in a dose-dependent manner. These results indicated that apoptosis in the ROS-dependent mitochondrial pathway mediates hepatotoxicity caused by TBBPA and TCBPA. The present study will facilitate an understanding of the toxicity mechanism of flame retardants.

Phototransformation of tetrabromobisphenol A in saline water under simulated sunlight irradiation

The widespread use of halogenated flame retardants in recent years has led to the accumulation of TBBPA in water, which may cause potential harm to living organisms. The phototransformation of the flame retardant TBBPA in alkaline saline water under simulated sunlight irradiation was investigated. The effects of abiotic factors such as the initial concentration of TBBPA, chloride ion concentration, solution pH, inorganic anions and cations, dissolved organic matter (DOM) were studied. The results showed that the phototransformation rate of TBBPA accelerated with the decrease of the initial concentration of TBBPA, the increase of chloride ion concentration and solution pH. The scavenging experiments showed that •OH, ¹O₂, O₂•^- and ³TBBPA* all participated in the phototransformation of TBBPA. The presence of NO₃^-, CO₃^2-, SO₄^2-, Mg²⁺, Ca²⁺, Fe³⁺ and fulvic acid (FA) all inhibited the phototransformation of TBBPA in the present study. The phototransformation products of TBBPA were detected by liquid chromatography-mass spectrometry (LC-MS), and the phototransformation pathways were proposed. This is the first report on the photo-induced generation of halogen exchange products from TBBPA in saline solutions, which will contribute to a better understanding of the environmental behavior and risks of BFRs in water.

Evaluating the Effects of BPA and TBBPA Exposure on Pregnancy Loss and Maternal-Fetal Immune Cells in Mice

BACKGROUND

Bisphenol A (BPA) exposure has been linked to miscarriages and pregnancy complications in humans. In contrast, the potential reproductive toxicity of BPA analogs, including tetrabromobisphenol A (TBBPA), is understudied. Furthermore, although environmental exposure has been linked to altered immune mediators, the effects of BPA and TBBPA on maternal-fetal immune tolerance during pregnancy have not been studied. The present study investigated whether exposure resulted in higher rates of pregnancy loss in mice, lower number of regulatory T cells (Tregs), and lower indoleamine 2,3 deoxygenase 1 (Ido1) expression, which provided evidence for mechanisms related to immune tolerance in pregnancy.

OBJECTIVES

The purpose of this investigation was to characterize the effects of BPA and TBBPA exposure on pregnancy loss in mice and to study the percentage and number of Tregs and Ido1 expression and DNA methylation.

METHODS

Analysis of fetal resorption and quantification of maternal and fetal immune cells by flow cytometry were performed in allogeneic and syngeneic pregnancies. Ido1 mRNA and protein expression, and DNA methylation in placentas from control and BPA- and TBBPA-exposed mice were analyzed using real-time quantitative polymerase chain reaction, immunofluorescence, and bisulfite sequencing analyses.

RESULTS

BPA and TBBPA exposure resulted in higher rates of hemorrhaging in early allogeneic, but not syngeneic, conceptuses. In allogeneic pregnancies, BPA and TBBPA exposure was associated with higher fetal resorption rates and lower maternal Treg number. Importantly, these differences were associated with lower IDO1 protein expression in trophoblast giant cells and higher mean percentage Ido1 DNA methylation in embryonic day 9.5 placentas from BPA- and TBBPA-exposed mice.

DISCUSSION

BPA- and TBBPA-induced pregnancy loss in mice was associated with perturbed IDO1-dependent maternal immune tolerance. https://doi.org/10.1289/EHP10640.

ZIF-8/nitrogen-doped reduced graphene oxide as thin film microextraction adsorbents for simultaneous determination of novel halogenated flame retardants in crayfish-aquaculture water systems

Novel halogenated flame retardants (HFRs) have attracted much attention due to their environmental hazard and adverse effects on human health. In this study, a sensitive and simultaneous method for the determination of six novel HFRs was developed, including tetrabromobisphenol A (TBBPA), tetrachlorobisphenolA, TBBPA bis(2-hydroxyethyl ether), TBBPA bis(allyl ether), TBBPA bis(2,3-dibromopropyl ether) and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine. ZIF-8 modified nitrogen-doped reduced graphene oxide (ZIF-8@N-rGO) was synthesized and coated onto a syringe filter to prepare a thin film microextraction (TFME) device. The adsorption capacities of ZIF-8@N-rGO for novel HFRs ranged from 50.98 to 112.84 mg g^-1, exhibiting good extraction efficiency through a combination of π-π, hydrophobic, and hydrogen bonding interactions. The TFME device was coupled to a high-performance liquid chromatography-ultraviolet detection system to simultaneously determine target HFRs in crayfish-aquaculture water systems. Under the optimal extraction parameters, the linearities ranged from 0.1 to 100 ng mL^-1. The method detection limits ranged from 0.030 to 0.14 ng mL^-1 and relative recoveries ranged from 88.6 to 106.2%. We found that novel HFRs were detected in water and crayfish samples and were primarily distributed in the viscera and head shell of the crayfish. The bioconcentration factors ranged from 0.25 to 19.20 L kg^-1, indicating non-bioaccumulation in the crayfish. This study provides valuable technology and information for potential health risks of exposure to novel HFRs from consuming crayfish.

Tetrabromobisphenol A induced reproductive endocrine-disrupting effects in mussel Mytilus galloprovincialis

Tetrabromobisphenol A (TBBPA) pollution in marine environmental media poses great risks to marine organisms due to its potential endocrine-disrupting effects. However, limited attention of TBBPA's endocrine-disrupting effects has been paid on marine invertebrates. In this work, the reproductive endocrine-disrupting effects of TBBPA were evaluated by observing the gametes development, quantifying the gender-specific gene expression, and determining vertebrate sex hormones in mussels Mytilus galloprovincialis treated with TBBPA for 30 days. Additionally, transcriptomic profiling and enzymes activities were conducted to investigate the potential mechanisms of reproductive endocrine-disrupting effects. We found that promotion of gametogenesis and alterations of vertebrate sex hormones occurred in TBBPA-treated mussels of both sexes. Meanwhile, estrogen sulfotransferase (SULT1E1) and steroid sulfatase (STS) were up-regulated at transcript level as a result of TBBPA treatments, suggesting that TBBPA disrupted the steroidogenesis in mussels through promoting steroids sulfonation and hydrolysis of sulfate steroids. The induction of SULTs for TBBPA biotransformation might be responsible for the dysregulation of steroidogenesis and steroids metabolism. Overall, these findings provide a new insight into assessing impact of TBBPA as well as TBBPA biomonitoring in marine environment.

Toxicity of Tetrabromobisphenol A and Its Derivative in the Mouse Liver Following Oral Exposure at Environmentally Relevant Levels

As typical brominated flame retardants (BFRs), tetrabromobisphenol A (TBBPA) and its derivative TBBPA-bis(2,3-dibromopropyl ether) (TBBPA-BDBPE) are ubiquitous in various environmental compartments. However, the potential health risk posed by these compounds, especially at environmentally relevant levels, remains unclear. In this study, using adult male mice, we investigated the toxicity of orally administered TBBPA and TBBPA-BDBPE at an environmentally relevant dose (57 nmol/kg body weight). After a single exposure and daily exposure, we assessed lipid metabolism homeostasis, the transcriptome, and immune cell components in the liver. We found that the single exposure to TBBPA or TBBPA-BDBPE alone increased the number of hepatic macrophages, induced alterations in the levels of lipids, including triacylglycerol and free fatty acids, and caused transcriptome perturbation. The results from the daily administration groups showed that TBBPA and TBBPA-BDBPE both significantly increased the triacylglycerol content; however, the elevation of hepatic macrophages was observed only in the TBBPA-BDBPE treatment group. This study confirmed that environmentally relevant levels of TBBPA and TBBPA-BDBPE are toxic to the liver. Our findings revealed that dysfunction of the liver is a health concern, following exposure to BFRs, even at very low concentrations. The chronic effects induced by TBBPA and its derivatives should be further investigated.

Co-metabolic degradation of tetrabromobisphenol A by Pseudomonas aeruginosa and its auto-poisoning effect caused during degradation process

In this study, Pseudomonas aeruginosa was applied to degrade tetrabromobisphenol A (TBBPA) with glucose as a co-metabolic substrate. Influencing factors of co-metabolic degradation such as pH, TBBPA and glucose concentration were examined and the degradation efficiency under optimal condition reached about 50% on the 7th day. The study also proved that the extracellular action, rather than intracellular one, played a leading role in TBBPA degradation. Five metabolites including debromination and beta-scission products were identified in this study. The extracellular active substance pyocyanin was considered as the origin of H₂O₂ and OH·. The variation of concentrations of H₂O₂ and OH· shared the same trend, they increased in the early days and then declined gradually. On the 1st day, the OD600 of P.aeruginosa in the co-metabolic group was 6.0 times higher than the initial value while total organic carbon (TOC) decreased about 78%, which might lead to the occurrence of pyocyanin auto-poisoning. Flow cytometry was applied to detect the cellular state of P.aeruginosa during degradation. The increasing intracellular ROS showed that cells were suffering from oxidative stress and the change of membrane potential revealed that cellular dysfunction had occurred since the 1st day. This research indicated that the toxic effect on P.aeruginosa was probably not directly correlated with TBBPA, but was caused by pyocyanin auto-poisoning.

Residual levels and risk assessment of tetrabromobisphenol A in Baiyang Lake and Fuhe river, China

Tetrabromobisphenol A (TBBPA) in water from Xiongan New Area was determined by gas chromatography-mass spectrometry (GC-MS), simultaneous with its risk assessment. The optimal extraction conditions, derivatization factors (such as derivation reagent amount, derivatization time and temperature), and dissolution solvent were determined by orthogonal experiment. These results indicated the optimum derivatization time and temperature were 70 °C and 30 min, respectively, whilst the amount of derivatization reagent (N,O-bis (trimethylsilyl) trifluoroacetamide) was 40 μL. The optimum extraction efficiency was obtained when using the mixture of hexane-dichloromethane (1:1, v:v) with salt concentration of 6 g/L. Using the sample of S9 as control, the recovery experiments were performed with three different spiked levels. The water samples of Baiyang Lake and Fuhe river were analyzed using the optimized conditions. Those results showed that the concentrations of TBBPA in samples ranged from 18.5 ng/L to 82.6 ng/L, which lies in the middle level of data previously published from other areas in China. The risk quotient (RQ) model was used to evaluate the above data. The results of exposure and risk assessment showed that the margin of exposure (MOE) was 1.28 × 10⁷-2.5 × 10⁷ and the RQ_max was 0.0266. The European Food Safety Authority (EFSA) standard and categories of RQ indicates that the estimated dietary exposure to TBBPA is unlikely to raise significant health concerns. This is the first report on the occurrence and risk assessment of TBBPA in waters from Xiongan New Area, which will be helpful for further risk assessment of other persistent organic pollutants. At present, the toxicological data of TBBPA in the biological body of Baiyang Lake is limited. In addition, more accurate and convenient approaches for the risk assessment of TBBPA should be explored.

Efficient removal of tetrabromobisphenol A (TBBPA) using sewage sludge-derived biochar: Adsorptive effect and mechanism

Sewerage sludge-derived biochars (SSDBCs) with high adsorption capacity and excellent recyclability were synthesized to remove tetrabromobisphenol A (TBBPA) in aqueous system. Scanning electron microscopy, elemental mapping via energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the morphology, composition, and microstructures. The maximum adsorption capacity of SSDBCs was about 87.02 mg g^-1 at 303 K and pH 7.5. The Langmuir isotherm demonstrated that the adsorption was mainly homogeneous and chemical processes. The kinetics of TBBPA removal well fitted the second-order dynamic model. Thermodynamic analysis showed that the adsorption was exothermic. The effect of π-π dispersive force and hydrogen bonding was proven as the main adsorption mechanism. Multiple cycle runs experiment revealed the excellent stability of recycled SSDBCs. This work provided a promising method of sludge resourceful treatment using an efficient, economic, cyclic, and convenient material for typical organic contaminant in the environment.

A rapid and simple fluorescence enzyme-linked immunosorbent assay for tetrabromobisphenol A in soil samples based on a bifunctional fusion protein

Tetrabromobisphenol A (TBBPA) is the largest brominated flame retardant which can be released to environment and cause long-term hazard. In this work, we developed a rapid and highly sensitive fluorescence enzyme-linked immunosorbent assay (FELISA) for monitoring of TBBPA in soil samples. TBBPA specific nanobody derived from camelid was fused with alkaline phosphatase to obtain the bi-functional fusion protein, which enable the specific binding of TBBPA and the generation of detection signal simultaneously. The assay showed an IC₅₀ of 0.23 ng g^-1, limit detection of 0.05 ng g^-1 and linear range from 0.1 to 0.55 ng g^-1 for TBBPA in soil samples. Due to the high resistance to organic solvents of the fusion protein, a simple pre-treatment by using 40% dimethyl sulfoxide (DMSO) as extract solvent can eliminate matrix effect and obtain good recoveries (ranging from 93.4% to 112.4%) for spiked soil samples. Good relationship between the results of the proposed FELISA and that of liquid chromatography tandem mass spectrometry (LC-MS/MS) was obtained, which indicated it could be a powerful analytical tool for determination of TBBPA to monitor human and environmental exposure.

Coupling mesoporous imprinted polymer based DGT passive samplers and HPLC: A new tool for in-situ selective measurement of low concentration tetrabromobisphenol A in freshwaters

Accurate measurement of tetrabromobisphenol A (TBBPA) is very important because of its widespread environmental pollution. Diffusive gradients in thin films technique (DGT), an in-situ passive sampling method, is regarded as a reliable and robust measurement technique. A new DGT technique based on mesoporous imprinted polymer was combined with high-pressure liquid chromatography (HPLC) method for sampling, preconcentration and monitoring low concentration TBBPA in natural waters. The diffusion coefficient of TBBPA through the diffusive gel was measured by diffusion cell test and simulated using mathematical expression. The effects of different ambient conditions were tested under laboratory conditions and the performance of DGT sampler was validated in natural waters. The diffusion coefficient of TBBPA in the diffusive gel was measured as 2.18 × 10^-6 cm² s^-1 and simulated as in the range 1.41-3.48 × 10^-6 cm² s^-1 by Amsden model. Comparison of experimental and theoretical data, the validity of the experimental method can be verified by the mathematical model. The binding agent with mesoporous imprinted polymer showed selective affinity to TBBPA and its adsorption rate met the requirement of DGT device. The DGT method detection limit was at the level of ng L^-1 for 7 days deployment. DGT sampler was suitable for application in aquatic environment with a range of pH (4.5-7.6), ionic strength (1 × 10^-4 - 0.5 mol L^-1), and dissolved organic matter (DOM) concentration (0-10 mg C L^-1). The coupling method of DGT and HPLC was a promising technique for in situ sampling, preconcentration and monitoring low concentration TBBPA in most typical natural waters.

In Vitro Effects of Bisphenol A and Tetrabromobisphenol A on Cell Viability and Reproduction-Related Gene Expression in Pituitaries from Sexually Maturing Atlantic Cod (Gadus morhua L.)

Bisphenol A (BPA) and tetrabromobisphenol A (TBBPA) are widely used industrial chemicals, ubiquitously present in the environment. While BPA is a well-known endocrine disruptor and able to affect all levels of the teleost reproductive axis, information regarding TBBPA on this subject is very limited. Using primary cultures from Atlantic cod (Gadus morhua), the present study was aimed at investigating potential direct effects of acute (72 h) BPA and TBBPA exposure on cell viability and the expression of reproductive-relevant genes in the pituitary. The results revealed that both bisphenols stimulate cell viability in terms of metabolic activity and membrane integrity at environmentally relevant concentrations. BPA had no direct effects on gonadotropin gene expression, but enhanced the expression of gonadotropin-releasing hormone (GnRH) receptor 2a, the main gonadotropin modulator in Atlantic cod. In contrast, TBBPA increased gonadotropin transcript levels but had no effect on GnRH receptor mRNA. In conclusion, both anthropogenic compounds display endocrine disruptive properties and are able to directly interfere with gene expression related to reproductive function in cod pituitary cells at environmentally relevant concentrations in vitro.

Spatial distribution of parabens, triclocarban, triclosan, bisphenols, and tetrabromobisphenol A and its alternatives in municipal sewage sludges in China

Parabens, triclocarban (TCC), triclosan (TCS), bisphenols (BPs), and tetrabromobisphenol A and its alternatives (TBBPAs) are used in a broad range of daily consumer products and industrial productions. Concerns have been raised over exposure of humans to these chemicals, because of their adverse health effects. However, information on the spatial distribution of parabens, TCC, TCS, BPs and TBBPAs in sludge from waste water treatment plants (WWTPs) in China is still limited. In this study, 19 endocrine disrupting chemicals, including six parabens, two antimicrobials (TCC and TCS), eight BPs and three TBBPAs, were determined in sludges from 46 WWTPs across China. Concentrations of target chemicals were found in a decreased order as: ∑(TCC+TCS) (mean: 3930, range: 1340-11,100ng/g dw)>∑₈BPs (201, 23.1-1240ng/g dw)>∑₆parabens (67.9, 10.4-272ng/g dw)>∑₃TBBPAs (18.4, 1.36-195ng/g dw). Methyl paraben (MeP), TCC, bisphenol A (BPA) and tetrabromobisphenol A (TBBPA) were the major compounds found in sludge, accounting for 89.0%, 57.7%, 85.8% and 93.3% of ∑₆parabens, ∑(TCC+TCS), ∑₈BPs and ∑₃TBBPAs, respectively. Elevated concentrations of BPs and TBBPAs were found in sludges from the Northeast China and Central South China (p<0.05), respectively, whereas there were no significant spatial difference in concentrations of parabens or antimicrobials among different geographical regions (p>0.05). Calculation of mass loading showed that sludge from East China (1340kg/yr) and South Central China (1060kg/yr) released relatively more such chemicals. This nationwide study provided baseline concentrations of these chemicals in sludges and estimated their environmental release through sludge in China.

Do G-protein coupled estrogen receptor and bisphenol A analogs influence on Leydig cell epigenetic regulation in immature boar testis ex vivo?

Organotypic culture of testicular fragments from 7-day-old male pigs (Polish White Large) was used. Tissues were treated with an antagonist of G-protein coupled estrogen receptor (GPER) (G-15; 10 nM), and bisphenol A (BPA), and its analogs (TBBPA, TCBPA; 10 nM) alone or in combination and analyzed using electron and light (stainings for collagen fibers, lipid droplet and autophagy markers) microscopes. In addition, mRNA and protein abundances and localization of molecules required for miRNA biogenesis and function (Drosha, Exportin 5; EXPO5, Dicer, and Argonaute 2; AGO2) were assessed together with calcium ion (Ca²⁺) and estradiol concentrations. Regardless of GPER blockade and/or treatment with BPA, TBBPA and TCBPA, there were no changes in Leydig cell morphology. Also, there were no changes in lipid droplet content and distribution but there were changes in lipid and autophagy protein abundance. In the interstitial tissue, there was an increase of collagen content, especially after treatment with BPA analogs and G-15 + BPA. Independent of the treatment, there was downregulation of EXPO5 and Dicer genes but the Drosha and AGO2 genes were markedly upregulated as a result of treatment with G-15 + BPA and TCBPA, respectively. There was always a lesser abundance of EXPO5 and AGO2 proteins regardless of treatment. There was markedly greater abundances of Drosha after G-15 + BPA treatment, and this also occurred for Dicer after treatment with G-15 + TCBPA. Immunolocalization of miRNA proteins indicated there was a cytoplasmic-nuclear pattern in control and treated cells. There was an increase of Ca²⁺ concentrations after treatment with G-15 and BPA analogs. Estradiol secretion decreased after antagonist and chemical treatments when these were administered alone, however, there was an increase in estradiol secretion after treatment with combinations of these compounds.

Tetrabromobisphenol A, hexabromocyclododecane isomers and polybrominated diphenyl ethers in foodstuffs from Beijing, China: Contamination levels, dietary exposure and risk assessment

Hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA) and polybrominated diphenyl ether (PBDEs) are three legacy brominated flame retardants (BFRs); however, they are still produced and used in China. In this study, these three BFRs were measured in commonly consumed animal-based and plant-based foodstuffs from Beijing, China, and the dietary intakes of these BFRs by adults in Beijing were estimated to assess the related health concerns. The median levels of TBBPA in animal-based foodstuffs ranged from <LOD to 8.03 ng/g lipid weight (lw), whereas those in all the plant-based food groups were lower than the LOD. The median levels of total HBCD in animal-based foodstuffs were from 1.14 to 5.65 ng/g lw, and α-HBCD was the predominant isomer. The median HBCD level in vegetables was 0.266 ng/g wet weight (ww), whereas γ-HBCD was the most abundant isomer. The median levels of total PBDEs in animal-based foodstuffs were from 3.22 to 13.7 ng/g lw, and BDE-209 was the most abundant congener, comprising a proportion of at least 85% of total PBDEs. The daily dietary intakes of TBBPA, HBCD and PBDEs for adults in Beijing were 2.52, 2.74 and 9.77 ng/kg body weight/day, respectively. Meat consumption was found to be the primary source of BFR dietary intake. A comparison between the calculated estimated daily intakes (EDIs) and the corresponding threshold reference values (TRVs) indicated that daily intake of BFRs via food consumption is unable to cause significant health risks. Likewise, the margin of exposures (MOEs) calculated following the European Food Safety Authority (EFSA) approach were far higher than the threshold, which also proved that the EDIs of BFRs are unlikely to raise significant health concerns.