Summary of historical terrestrial toxicity data for the brominated flame retardant tetrabromobisphenol A (TBBPA): effects on soil microorganisms, earthworms, and seedling emergence

Unveiling the occurrence, distribution, removal, and environmental impacts of 65 emerging contaminants in neglected fresh leachate from municipal solid waste incineration plants

Emerging contaminants (ECs) are commonly found in environmental media. Yet leachate from municipal solid waste incineration plants (MSWIPs), which can serve as a reservoir for various contaminants, including ECs, has received little investigation. To address this gap, 65 ECs were analyzed in the fresh leachate and biological effluent from three major MSWIPs in Shanghai. Results indicated that over half (56%) of the 65 ECs were detected in fresh leachate. Different ECs would be removed to varying degrees after biological treatment, including polycyclic aromatic hydrocarbons (PAHs) (65%), polybrominated diphenyl ethers (PBDEs) (51%), phthalate esters (PAEs) (36%), and organophosphorus pesticides (OPPs) (34%). Notably, for tetrabromobisphenol A (TBBPA), a PBDE substitute, only 2% was removed after biological treatment, while polychlorinated biphenyls (PCBs) were effectively removed at 83%. Water solubility and the octanol-water partition coefficient are key factors influencing the distribution and removal of ECs in leachate. the effluent will still contain refractory ECs even after the biological treatment. These residual ECs discharged to sewers can impact wastewater treatment plants or contaminate surface water and groundwater. These findings provide insights into the leachate contamination by ECs, their environmental fate, factors affecting their behavior, and potential environmental impacts.

Two halogenated flame retardants and cadmium in the soil-rice system: sorption, root uptake, and translocation

The migration and transformation of Tetrabromobisphenol A (TBBPA), DechloranePlus (DP), and cadmium in soil-rice system was investigated, and the influence on the quality of two varieties of rice was studied. The degradation half-lives of TBBPA, BBPAs, syn-DP, and anti-DP were 23.18 ~ 26.36 days, 30.14 ~ 36.10 days, 72.96-81.55 days, and 169.06-198.04 days in the soil. TBBPA was gradually degraded to tri-BBPA, di-BBPA, mono-BBPA, and bisphenol A by the debromination. TBBPA and its bromide metabolites could be bioaccumulated in different tissues of rice; mono-BBPA and bisphenol A was easy to accumulate in the stems, and bisphenol A was easy to bioaccumulate in the grain. Comparing with single and compound pollution, there was no significant difference in bioaccumulation factors of two rice species. The grain of NO7 had stronger bioaccumulation ability to mono-BBPA and BPA than NO1, and there is no significant difference in TBBPA. Residual level of DP in the rice: roots > stems > grain; there was no significant difference in bioaccumulation of two varieties of rice. Cadmium was easily bioaccumulated in the roots of rice and translocated to the rice stems and grains. NO7 rice had stronger bioaccumulation and transport capacity than NO1. The effects of the three pollutants on the quality of two varieties of rice varied significantly; cadmium had the greatest effect on the iodine blue value (BV) and amylase activity of the grain. This study proved that selecting rice varieties with low bioaccumulation to polluters can effectively reduce the risk of the food chain harming human health.

Combined toxicity of 3,5,6-trichloro-2-pyridinol and 2-(bromomethyl)naphthalene in the early stages of zebrafish (Danio rerio) embryos: Abnormal heart development at lower concentrations via differential expression of heart forming-related genes

Combined toxicity can occur in the environment according to the combination of single substances, and the combination works additively or in a synergistic or antagonistic mode. In our study, 3,5,6-trichloro-2-pyridinol (TCP) and 2-(bromomethyl)naphthalene (2-BMN) were used to measure combined toxicity in zebrafish (Danio rerio) embryos. As the lethal concentration (LC) values were obtained through single toxicity, the lethal effects at all combinational concentrations were considered synergistic by the Independent Action model. At 96 hpf, the combined toxicity of TCP LC₁₀ + 2-BMN LC₁₀, the lowest combinational concentration, resulted in high mortality, strong inhibition of hatching, and various morphological changes in zebrafish embryos. Combined treatment resulted in the downregulation of cyp1a, leading to reduced detoxification of the treated chemicals in embryos. These combinations may enhance endocrine-disrupting properties via upregulation of vtg1 in embryos, and inflammatory responses and endoplasmic reticulum stress were found to upregulate il-β, atf4, and atf6. These combinations might induce severe abnormal cardiac development in embryos via downregulation of myl7, cacna1c, edn1, and vmhc expression, and upregulation of the nppa gene. Therefore, the combined toxicity of these two chemicals was observed in zebrafish embryos, which proves that similar substances can exhibit stronger combined toxicity than single toxicity.

Tetrabromobisphenol a exacerbates the overall radioactive hazard to zebrafish (Danio rerio)

The major health risks of dual exposure to two hazardous factors of plastics and radioactive contamination are obscure. In the present study, we systematically evaluated the combinational toxic effects of tetrabromobisphenol A (TBBPA), one of the most influential plastic ingredients, mainly from electronic wastes, and γ-irradiation in zebrafish for the first time. TBBPA (0.25 μg/mL for embryos and larvae, 300 μg/L for adults) contamination aggravated the radiation (6 Gy for embryos and larvae, 20 Gy for adults)-induced early dysplasia and aberrant angiogenesis of embryos, further impaired the locomotor vitality of irradiated larvae, and worsened the radioactive multiorganic histologic injury, neurobehavioural disturbances and dysgenesis of zebrafish adults as well as the inter-generational neurotoxicity in offspring. TBBPA exaggerated the radiative toxic effects not only by enhancing the inflammatory and apoptotic response but also by further unbalancing the endocrine system and disrupting the underlying gene expression profiles. In conclusion, TBBPA exacerbates radiation-induced injury in zebrafish, including embryos, larvae, adults and even the next generation. Our findings provide new insights into the toxicology of TBBPA and γ-irradiation, shedding light on the severity of cocontamination of MP components and radioactive substances and thereby inspiring novel remediation and rehabilitation strategies for radiation-injured aqueous organisms and radiotherapy patients.

Determination of Apoptotic Mechanism of Action of Tetrabromobisphenol A and Tetrabromobisphenol S in Human Peripheral Blood Mononuclear Cells: A Comparative Study

Background: Tetrabromobisphenol A (TBBPA) is the most commonly used brominated flame retardant (BFR) in the industry. TBBPA has been determined in environmental samples, food, tap water, dust as well as outdoor and indoor air and in the human body. Studies have also shown the toxic potential of this substance. In search of a better and less toxic BFR, tetrabromobisphenol S (TBBPS) has been developed in order to replace TBBPA in the industry. There is a lack of data on the toxic effects of TBBPS, while no study has explored apoptotic mechanism of action of TBBPA and TBBPS in human leukocytes. Methods: The cells were separated from leucocyte-platelet buffy coat and were incubated with studied compounds in concentrations ranging from 0.01 to 50 µg/mL for 24 h. In order to explore the apoptotic mechanism of action of tested BFRs, phosphatidylserine externalization at cellular membrane (the number of apoptotic cells), cytosolic calcium ion and transmembrane mitochondrial potential levels, caspase-8, -9 and -3 activation, as well as PARP-1 cleavage, DNA fragmentation and chromatin condensation in PBMCs were determined. Results: TBBPA and TBBPS triggered apoptosis in human PBMCs as they changed all tested parameters in the incubated cells. It was also observed that the mitochondrial pathway was mainly involved in the apoptotic action of studied compounds. Conclusions: It was found that TBBPS, and more strongly TBBPA, triggered apoptosis in human PBMCs. Generally, the mitochondrial pathway was involved in the apoptotic action of tested compounds; nevertheless, TBBPS more strongly than TBBPA caused intrinsic pathway activation.

Tetrabromobisphenol A (TBBPA) anaerobic biodegradation occurs during acidogenesis

This is the first study to bring evidence on the anaerobic biodegradation of TBBPA occurring during acidogenesis in domestic sewage at environmentally relevant concentrations by complex microbial communities. This was accomplished by continuously operating two anaerobic structured bed reactors (ASTBR) for over 100 days under acidogenic (Acidogenic Reactor, AR) and multistep methanogenic (Methanogenic Reactor, MR) conditions. In the AR, the temporal carbohydrates consumption and the acetic acid production were strongly correlated with TBBPA removal by the Pearson's test. The spatial concentration of TBBPA and carbohydrates along the MR and the kinetic degradation profiles corroborate the AR results. It is hypothesized that TBBPA biodegradation in the studied conditions occurs during acidogenesis via the cometabolism supported by non-specific enzymes and the metabolism (dehalorespiration) established by electrons donors such as H₂, which are both produced during the macrocomponents breakdown in the early stages of the anaerobic digestion. The TBBPA mass balance showed that approximately 86.8 ± 0.05% and 97 ± 0.01% of the removed TBBPA was biodegraded in the AR and MR, respectively. Furthermore, TBBPA biodegradation went further than reductive debromination as total phenols were detected in the reactors' effluent.

Remarkable promotion in particle dispersion and electron transfer capacity of sulfidated nano zerovalent iron by coating alginate polymer

Alginate has been widely employed to increase the performance of nanoscale zerovalent iron (nZVI)-based materials for site remediation. Yet, the effects of alginate on reactivity of sulfidated nZVI (an efficient reductant material) towards contaminants have been understood poorly. In this study, we have developed a one-step synthesis of alginate-coated sulfidated nZVI (S-nZVI@alginate) under air atmosphere and evaluated the reactivity of S-nZVI@alginate towards tetrabromobisphenol A (TBBPA) debromination. Surface analysis shows that S-nZVI has been successfully coated by alginate through the interaction of OH and COO^- groups of alginate with Fe species. The coating of alginate increases particle stability and dispersion under various conditions and facilitates FeS precipitation on the particle surface. Reactivity experiments show that the coating of alginate significantly enhances TBBPA debromination by S-nZVI. The optimized alginate to Fe weight ratio of S-nZVI@alginate is 0.06, with ~3-fold greater TBBPA debromination rate than S-nZVI. S-nZVI@alginate can completely debrominate TBBPA into bisphenol A via a four-sequential step debromination pathway while S-nZVI not. Its superior reactivity may be attributed to that the formation of alginate-Fe complex can lower the redox potential of Fe species to accelerate electron transfer on the particle surface. The TBBPA debromination rate by S-nZVI@alginate is initially enhanced followed by a decrease with an increase in TBBPA concentration, while it can increase 3.3-, 8.9- and 5.6-fold by increasing S-nZVI@alginate dosage, decreasing pH and adding co-contaminant Cd²⁺, respectively. S-nZVI@alginate has greater performance in aging and reusability tests than S-nZVI, and achieves rapid TBBPA removal from wastewater, which may be due to the role of alginate on inhibiting surface oxidation of Fe and S species. Taken together, these results suggest that S-nZVI@alginate provides better reactivity, longevity and reusability than S-nZVI, having the great potential for application into site remediation.

Application of Dispersive Liquid-Liquid Microextraction Followed by High-Performance Liquid Chromatography/Tandem Mass Spectrometry Analysis to Determine Tetrabromobisphenol A in Complex Matrices

An accurate and sensitive ultrasound-dispersive liquid-liquid microextraction technique followed by high-performance liquid chromatography separation coupled with electrospray ionization tandem mass spectrometry detection method to determine the presence of tetrabromobisphenol A (TBBPA) in complex environmental matrices is proposed. The miniaturized procedure was used to extract and quantify the analyte in domestic sewage, anaerobic sludge, and the aquatic test organism species Daphnia magna and Chironomus sancticaroli, which are standardized organisms for ecotoxicity bioassays. Limits of detection of 2 ng L^-1 (domestic sewage), 2 ng g^-1 (anaerobic sludge), 0.25 ng g^-1 (D. magna), and 5 ng g^-1 (C. tentans) were obtained. The presence of TBBPA was determined in domestic sewage and anaerobic sludge from an anaerobic batch bioreactor at a concentration of 0.2 ± 0.03 μg L^-1 and 507 ± 79 ng g^-1 , respectively. In D. magna and C. sancticaroli exposed to TBBPA in an acute toxicity bioassay, the micropollutant accumulated at 3.74 and 8.87 μg g^-1 , respectively. The proposed method is a simple and cost-effective tool to determine TBBPA environmental occurrence and biomagnification potential compared with conventional extraction methods. To the best of our knowledge, this is the first liquid-liquid miniaturized extraction method to be applied to D. magna and C. sancticaroli. Environ Toxicol Chem 2020;39:2147-2157. © 2020 SETAC.

Chemical Structure-Related Adipogenic Effects of Tetrabromobisphenol A and Its Analogues on 3T3-L1 Preadipocytes

Tetrabromobisphenol A (TBBPA), the most widely used brominated flame retardant, is reported to potentially possess risks in inducing obesity or obesity-related metabolic diseases. Considering the increasing environmental contamination of TBBPA analogues and their high structural similarities to the parent compound, whether they could influence adipogenesis or not remains to be elucidated. In this study, two of the most prevalent TBBPA derivatives [i.e., TBBPA bis(allyl ether) (TBBPA-BAE) and TBBPA bis(2,3-dibromopropyl ether) (TBBPA-BDBPE)] and their byproducts [i.e., TBBPA mono(allyl ether) (TBBPA-MAE) and TBBPA mono(2,3-dibromopropyl ether) (TBBPA-MDBPE)], together with TBBPA, were screened for their capacities in activating peroxisome proliferator-activated receptor-γ (PPARγ) and glucocorticoid receptor (GR), the key nuclear receptors involved in adipogenesis, and their structure-related effects on differentiation of 3T3-L1 preadipocytes were explored. The results indicated that the binding affinities of TBBPA and its analogues for the PPARγ ligand-binding domain (PPARγ-LBD) and GR, as well as their effects on PPARγ transactivation, followed the order of TBBPA > TBBPA-MAE > TBBPA-MDBPE > TBBPA-BAE, TBBPA-BDBPE. Nevertheless, TBBPA-MAE and TBBPA-MDBPE showed higher potentials in promoting adipogenesis in 3T3-L1 cells than did TBBPA, as evidenced by intracellular triglyceride contents and adipogenic biomarkers at both protein and transcriptional levels. The etherified group at position 4 of TBBPA phenolic rings was crucial in chemical-induced adipogenic effects, which was related with the recruitment of PPARγ and GR-mediated networks and some other unidentified signaling pathways. The findings on the disturbance of TBBPA analogues on adipogenesis revealed their potential risk in causing obesity and other lipid metabolism-related human health concerns.

Absence of neurotoxicity and lack of neurobehavioral consequences due to exposure to tetrabromobisphenol A (TBBPA) exposure in humans, animals and zebrafish

Tetrabromobisphenol A (2,2',6,6'-tetrabromo-4,4'-isopropylidenediphenol, CAS no. 79-94-7) (TBBPA) is an effective brominated flame retardant present in many consumer products whose effectiveness is attributable to its ability to retard flames and consequently save human lives. Toxicokinetic studies revealed that TBBPA when absorbed via the gastrointestinal tract is rapidly metabolized to glucuronide or sulfate metabolites which are rapidly eliminated by the kidney. TBBPA does not accumulate in the body and there is no evidence that the parent compound is present in the brain. Although this brominated flame retardant was detected in human breast milk and serum, there was no evidence that TBBPA reached the brain in in vivo animal studies as reflected by the absence of neuropathological, neurotoxic, or behavioral alterations indicating that the central nervous system is not a target tissue. These animal investigations were further supported by use of the larval/embryo observations that TBBPA did not produce behavioral changes in a larval/embryo zebrafish a model of chemical-induced neurotoxicity. Although some protein expressions were increased, deceased or not affected in the blood-brain barrier indicating no evidence that TBBPA entered the brain, the changes were contradictory, or gender related, and behavior was not affected supporting that this compound was not neurotoxic. Taken together, TBBPA does not appear to target the brain and is not considered as a neurotoxicant.

Review of historical aquatic toxicity and bioconcentration data for the brominated flame retardant tetrabromobisphenol A (TBBPA): effects to fish, invertebrates, algae, and microbial communities

This paper summarizes the historical and recent research on the aquatic toxicology and bioconcentration potential of tetrabromobisphenol A (TBBPA), a major flame retardant in electronics. Historical studies on TBBPA are presented in detail, and are compared with more recent research. The historical studies have not been published to date, though they were pivotal in regulatory assessments by the European Union, Canada, and the USA. These assessments have enabled the use of TBBPA as a flame retardant in electronic applications, to the present. The studies were conducted under a Test Rule by the US Environmental Protection Agency in 1987, and were sponsored by member companies of the North American Flame Retardants Alliance (NAFRA) through the American Chemistry Council. The studies were conducted under Good Laboratory Practice procedures, and include 6 acute toxicity tests of TBBPA with fish, invertebrates, algae, and microbes, eight chronic tests, and three bioconcentration studies with fish and invertebrates. Methods and empirical data for each study are detailed in an electronic supplement. Results of the NAFRA studies are compared with recent findings on TBBPA toxicity. Molluscan shell growth may be uniquely sensitive to TBBPA, more sensitive than chronic fish or crustacean toxicity endpoints. Several of the NAFRA studies and several independent studies have reported toxicities exceeding the empirical water solubility limits of TBBPA (in the range of 2.0 mg/L depending on pH). The validity of these results is discussed.