Identification and quantification of TBBPA and its metabolites in adult zebrafish by high resolution liquid chromatography tandem mass spectrometry

A review of occurrence, bioaccumulation, and fate of novel brominated flame retardants in aquatic environments: A comparison with legacy brominated flame retardants

Novel brominated flame retardants (NBFRs) have been developed as replacements for legacy brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs). The prevalence of NBFRs in aquatic environments has initiated intense concerns that they resemble to BFRs. To comprehensively elucidate the fate of NBFRs in aquatic environments, this review summarizes the physico-chemical properties, distribution, bioaccumulation, and fates in aquatic environments. 1,2-bis(2,3,4,5,6-pentabromophenyl) ethane (DBDPE) as the major substitute for PBDEs is the primary NBFR. The release from industrial point sources such as e-waste recycling stations is the dominant way for NBFRs to enter the environment, which results in significant differences in the regional distribution of NBFRs. Sediment is the major sink of NBFRs attributed to the high hydrophobicity. Significantly, there is no decreasing trend of NBFRs concentrations, while PBDEs achieved the peak value in 1970-2000 and decreased gradually. The bioaccumulation of NBFRs is reported in both field studies and laboratory studies, which is regulated by the active area, lipid contents, trophic level of aquatic organisms, and the log KOW of NBFRs. The biotransformation of NBFRs showed similar metabolism patterns to that of BFRs, including debromination, hydroxylation, methoxylation, hydrolysis, and glycosylation. In addition, NBFRs show great potential in trophic magnification along the aquatic food chain, which could pose a higher risk to high trophic-level species. The passive uptake by roots dominates the plant uptake of NBFRs, followed by acropetal and basipetal bidirectional transportation between roots and leaves in plants. This review will provide the support to understand the current pollution characteristics of NBFRs and highlight perspectives for future research.

Composition, Release, and Transformation of Earthworm Tissue-Bound Residues of Tetrabromobisphenol A in Soil

Earthworms accumulate organic pollutants to form earthworm tissue-bound residues (EBRs); however, the composition and fate of EBRs in soil remain largely unknown. Here, we investigated the fate of tetrabromobisphenol A (TBBPA)-derived EBRs in soil for 250 days using a 14C-radioactive isotope tracer and the geophagous earthworm Metaphire guillelmi. The EBRs of TBBPA in soil were rapidly transformed into nonextractable residues (NERs), mainly in the form of sequestered and ester-linked residues. After 250 days of incubation, 4.9% of the initially applied EBRs were mineralized and 69.3% were released to extractable residues containing TBBPA and its transformation products (TPs, generated mainly via debromination, O-methylation, and skeletal cleavage). Soil microbial activity and autolytic enzymes of earthworms jointly contributed to the release process. In their full-life period, the earthworms overall retained 24.1% TBBPA and its TPs in soil and thus prolonged the persistence of these pollutants. Our study explored, for the first time, the composition and fate of organic pollutant-derived EBRs in soil and indicated that the decomposition of earthworms may release pollutants and cause potential environmental risks of concern, which should be included in both environmental risk assessment and soil remediation using earthworms.

Co-occurrence of tetrabromobisphenol a and debromination products in human hair across China: Implications for exposure sources and health effects on metabolic syndrome

The large usage of Tetrabromobisphenol A (TBBPA) in consumer products leads to ubiquitous distribution globally, however, studies on the occurrence of their debromination compounds were rather scarce. Also, though many studies illustrate the effectiveness of hair analysis to assess human exposure to organic pollutants, evidence on the associations with health implications is still fairly limited. Herein, 598 participants from across China were employed to investigate chronic, low-level exposure to TBBPA and debromination products by hair analysis. The geomean concentrations of TBBPA, 2,2',6-tribromobisphenol A (Tri-BBPA), 2,2'- and 2,6-dibromobisphenol A (Di-BBPA), and 2-monobromobisphenol A (Mo-BBPA) were 1.07, 0.145, 0.135, and 0.894 ng/g, respectively, indicating nonnegligible health risks of debromination products. Hair analyte levels correlated with population age and population density among sampling regions. Sexual- and spatial-variations were observed with higher concentrations in females and in E-waste recycling sites. Logistic regression models showed that TBBPA exposure (adjusted odds ratio (OR): 1.02, 95 % confidential interval (CI): 1.01-1.05) was positively associated with risk of metabolic syndrome by adjusting for various covariates. These findings imply usefulness of hair as an alternative biomonitoring tool to assess human exposure to TBBPA and relative health effects, which highlights public concerns on co-exposure to these chemicals.

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.

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%.

Methods for the analysis of endocrine disrupting chemicals in selected environmental matrixes

Endocrine disrupting chemicals (EDCs) are heterogenous in structure, chemical and physical properties, and their capacity to partition into various environmental matrixes. In many cases, these chemicals can disrupt the endocrine systems of vertebrate and invertebrate organisms when present at very low concentrations. Therefore, sensitive and varied analytical methods are required to detect these compounds in the environment. This review summarizes the analytical methods and instruments that are most used to monitor for EDCs in selected environmental matrixes. Only those matrixes for which there is a clear link between exposures and endocrine effects are included in this review. Also discussed are emerging methods for sample preparation and advanced analytical instruments that provide greater selectivity and sensitivity.

Metabolic transformation of environmentally-relevant brominated flame retardants in Fauna: A review

Over the past few decades, production trends of the flame retardant (FR) industry, and specifically for brominated FRs (BFRs), is for the replacement of banned and regulated compounds with more highly brominated, higher molecular weight compounds including oligomeric and polymeric compounds. Chemical, biological, and environmental stability of BFRs has received some attention over the years but knowledge is currently lacking in the transformation potential and metabolism of replacement emerging or novel BFRs (E/NBFRs). For articles published since 2015, a systematic search strategy reviewed the existing literature on the direct (e.g., in vitro or in vivo) non-human BFR metabolism in fauna (animals). Of the 51 papers reviewed, and of the 75 known environmental BFRs, PBDEs were by far the most widely studied, followed by HBCDDs and TBBPA. Experimental protocols between studies showed large disparities in exposure or incubation times, age, sex, depuration periods, and of the absence of active controls used in in vitro experiments. Species selection emphasized non-standard test animals and/or field-collected animals making comparisons difficult. For in vitro studies, confounding variables were generally not taken into consideration (e.g., season and time of day of collection, pollution point-sources or human settlements). As of 2021 there remains essentially no information on the fate and metabolic pathways or kinetics for 30 of the 75 environmentally relevant E/BFRs. Regardless, there are clear species-specific and BFR-specific differences in metabolism and metabolite formation (e.g. BDE congeners and HBCDD isomers). Future in vitro and in vivo metabolism/biotransformation research on E/NBFRs is required to better understand their bioaccumulation and fate in exposed organisms. Also, studies should be conducted on well characterized lab (e.g., laboratory rodents, zebrafish) and commonly collected wildlife species used as captive models (crucian carp, Japanese quail, zebra finches and polar bears).

High throughput extraction strategy for simultaneous analysis of 19 tetrabromobisphenol A and halogenated carbazole analogs in seafood

Tetrabromobisphenol A (TBBPA), halogenated carbazole (HCZ), and their analogs are the emerging pollutants invading the marine environment. So far, a few methods have been reported for the simultaneous analysis of these pollutants due to their large polarity difference. In this study, an effective extraction and cleanup strategy was developed for the simultaneous determination of 19 TBBPA and HCZ congeners in seafood. The 19 analytes could be directly analyzed through high performance liquid chromatography after ultrasonic extraction (methanol, duplicate ethyl acetate-acetone (1:1, v/v)) and gel permeation chromatography cleanup. The acceptable spike-recoveries were within 65.7-118.3%; the precision was intra-/inter-day RSDs: 0.0-6.7%/0.0-8.5%; and the matrix effects were between -14.1% and 12.4%. The detection limits and quantification limits were 0.002-0.014 and 0.020-0.200 µg g^-1 dw, respectively. Additionally, this method successfully analyzed the seafood samples and the concentrations of these analytes were in range of nd-5.4 µg g^-1 dw.