Determination of urinary bromophenols (BrPs) as potential biomarkers for human exposure to polybrominated diphenyl ethers (PBDEs) using gas chromatography-tandem mass spectrometry (GC–MS/MS)

Update of the risk assessment of brominated phenols and their derivatives in food

The European Commission asked EFSA to update its 2012 risk assessment on brominated phenols and their derivatives in food, focusing on five bromophenols and one derivative: 2,4,6-tribromophenol (2,4,6-TBP), 2,4-dibromophenol (2,4-DBP), 4-bromophenol (4-BP), 2,6-dibromophenol (2,6-DBP), tetrabrominated bisphenol S (TBBPS), tetrabromobisphenol S bismethyl ether (TBBPS-BME). Based on the overall evidence, the CONTAM Panel considered in vivo genotoxicity of 2,4,6-TBP to be unlikely. Effects in liver and kidney were considered as the critical effects of 2,4,6-tribromophenol (2,4,6-TBP) in studies in rats. A BMDL10 of 353 mg/kg body weight (bw) per day for kidney papillary necrosis in male rats was identified and was selected as the reference point for the risk characterisation. The derivation of a health-based guidance value was not considered appropriate due to major limitations in the toxicological database. Instead, the margin of exposure (MOE) approach was applied to assess possible health concerns. Around 78,200 analytical results for 2,4,6-TBP in food were used to estimate dietary exposure for the European population. Considering the resulting MOE values, all far above an MOE of 6000 that does not raise a health concern, and accounting for the uncertainties affecting the exposure and hazard assessments, the CONTAM Panel concluded with at least 95% probability that the current dietary exposure to 2,4,6-TBP does not raise a health concern. Due to lack of occurrence data, no risk assessment could be performed for breastfed or formula-fed infants. No risk characterisation could be performed for any of the other brominated phenols and derivatives included in the assessment, due to lack of data both on the toxicity and occurrence.

In-situ acetylation followed by liquid-liquid extraction and gas chromatography - mass spectrometry for the determination of bromophenols in urine

A novel and simple method combining in-situ acetylation, liquid-liquid extraction and gas chromatography-mass spectrometry (GC-MS) has been developed for the quantification of 10 bromophenols in urine, used as biomarkers of exposure to polybrominated diphenyl ethers. The analytical process involves an enzymatic hydrolysis of the bromophenol glucuronide fraction followed by an aqueous derivatization of the phenol group with acetic anhydride. A subsequent liquid-liquid extraction of the sample with hexane allows the injection of the organic layer, using a programmed temperature vaporizer, into a gas chromatograph coupled to a single quadrupole mass spectrometer. Quantification is performed by the standard addition method. Limits of detection are in the pg mL-1 range. Trueness, assessed in terms of percentages of recovery, varies between 100 % and 118 % in synthetic urine and between 79 % and 117 % in human urine. Precision, assessed at two different levels, 0.25 ng mL-1 and 2.5 ng mL-1, shows values of relative standard deviation below 14 % both in intra- and inter-day studies for both matrices. The method has been applied to the analysis of seven urine samples, measuring concentrations higher than the LOQ in three of them. These levels are in agreement with others found in literature, but they have been obtained by applying a much simpler and faster protocol. In addition, the replacement of silylating reagents by acetic anhydride, to derivatize the phenol moiety, provides a greener alternative to other GC-MS procedures published up to date.

Simultaneous determination of 19 bromophenols by gas chromatography-mass spectrometry (GC-MS) after derivatization

Bromophenols (BPs) are a class of ubiquitous emerging halogenated pollutants. Their 19 congeners are problematically separated and detected. This work described the separation and detection of 19 BP congeners by gas chromatography-mass spectrometry (GC-MS). Investigations into the derivatization of bromophenols were carried out using two silylation reagents (N,O-bis(trimethylsilyl)trifluoroacetamide and N-methyl-N-(trimethylsily)trifluoroacetamide), two alkylation reagents (methyl iodide and trimethylsilyldiazomethane) and acetic anhydride prior to GC-MS analysis. Optimal chromatographic separation, sensitivity, and linearity were achieved after BP derivatization using acetic anhydride, featuring the equipment detection limits of 0.39-1.26 pg and correlation coefficients of 0.9948-0.9999 (linear range: 0.5-250 ng mL-1) for all 19 BP congeners. Furthermore, the simultaneous determination of 19 bromophenols and 19 bromoanisoles, common environmental transformation products of BPs, is also demonstrated. The improved analytical performance on GC-MS after derivatization would benefit investigations on the environmental origins, behaviors and fates of BPs and their environmental metabolites.

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

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

The role of sample preparation in suspect and non-target screening for exposome analysis using human urine

The use of suspect and non-target screening (SNTS) for the characterization of the chemical exposome employing human biofluids is gaining attention. Among the biofluids, urine is one of the preferred matrices since organic xenobiotics are excreted through it after metabolization. However, achieving a consensus between selectivity (i.e. preserving as many compounds as possible) and sensitivity (i.e. minimizing matrix effects by removing interferences) at the sample preparation step is challenging. Within this context, several sample preparation approaches, including solid-phase extraction (SPE), liquid-liquid extraction (LLE), salt-assisted LLE (SALLE) and dilute-and-shoot (DS) were tested to screen not only exogenous compounds in human urine but also their phase II metabolites using liquid-chromatography coupled to high-resolution tandem mass spectrometry (LC-HRMS/MS). Additionally, enzymatic hydrolysis of phase II metabolites was evaluated. Under optimal conditions, SPE resulted in the best sample preparation approach in terms of the number of detected xenobiotics and metabolites since 97.1% of the total annotated suspects were present in samples extracted by SPE. In LLE and SALLE, pure ethyl acetate turned out to be the best extractant but fewer suspects than with SPE (80.7%) were screened. Lastly, only 52.5% of the suspects were annotated in the DS approach, showing that it could only be used to detect compounds at high concentration levels. Using pure standards, the presence of diverse xenobiotics such as parabens, industrial chemicals (benzophenone-3, caprolactam and mono-2-ethyl-5-hydroxyhexyl phthalate) and chemicals related to daily habits (caffeine, cotinine or triclosan) was confirmed. Regarding enzymatic hydrolysis, only 10 parent compounds of the 44 glucuronides were successfully annotated in the hydrolysed samples. Therefore, the screening of metabolites in non-hydrolysed samples through SNTS is the most suitable approach for exposome characterization.

Apoptosis-Inducing Potential of Selected Bromophenolic Flame Retardants 2,4,6-Tribromophenol and Pentabromophenol in Human Peripheral Blood Mononuclear Cells

(1) Background: 2,4,6-Tribromophenol (2,4,6-TBP) and pentabromophenol (PBP) are utilized as brominated flame retardants (BFRs) in order to reduce the combustion of materials used in various utility products. The presence of 2,4,6-TBP and PBP has been reported in environmental samples as well as in inhaled air, dust, food, drinking water, and the human body. To date, there are limited data concerning the toxic action of 2,4,6-TBP and particularly PBP, and no study has been conducted to assess the apoptotic mechanism of action of these substances in human leukocytes. (2) Methods: PBMCs were isolated from leukocyte–platelet buffy coat and treated with tested substances in concentrations ranging from 0.01 to 50 µg/mL for 24 h. The apoptotic mechanism of action of the tested BFRs was assessed by the determination of phosphatidylserine exposure on the PBMCs surface, the evaluation of mitochondrial potential and cytosolic calcium ion levels, and the determination of caspase-8, -9, and -3 activation. Moreover, poly (ADP-ribose) polymerase-1 (PARP-1) cleavage, DNA fragmentation, and chromatin condensation were analyzed. (3) Results: 2,4,6-TBP and, more strongly, PBP induced apoptosis in PBMCs, changing all tested parameters. It was also found that the mitochondrial pathway was mainly involved in the apoptosis of PBMCs exposed to the studied compounds. (4) Conclusions: 2,4,6-TBP and PBP triggered apoptosis in human PBMCs, and some observed changes occurred at 2,4,6-TBP concentrations that were detected in humans occupationally exposed to this substance.

Genotoxic Mechanism of Action of TBBPA, TBBPS and Selected Bromophenols in Human Peripheral Blood Mononuclear Cells

Bromophenolic flame retardants (BFRs) are a large group of synthetic substances used in the industry in order to reduce the flammability of synthetic materials used in electrical and electronic devices, textiles, furniture and other everyday products. The presence of BFRs has been documented in the environment, food, drinking water, inhaled dust and the human body. Due to the widespread exposure of the general population to BFRs and insufficient knowledge on their toxic action, including genotoxic potential, we have compared the effect of tetrabromobisphenol A (TBBPA), tetrabromobisphenol S (TBBPS), 2,4,6,-tribromophenol (2,4,6-TBP) and pentabromophenol (PBP) on DNA damage in human peripheral blood mononuclear cells (PBMCs) (playing a crucial role in the immune system) as well as examined underlying mechanism of action of these substances. The cells were incubated for 24 h with studied compounds in the concentrations ranging from 0.01 to 10 µg/mL. The study has shown that examined BFRs induced single and, to a lesser extent, double strand-breaks formation and caused oxidative damage to pyrimidines, and particularly to purines in the incubated cells. PBMCs efficiently repaired the DNA strand-breaks induced by BFRs, but they were unable to remove completely damaged DNA (except cells treated with TBBPS). The greatest changes in the above-mentioned parameters were observed in cells incubated with TBBPA, while the smallest in PBMCs treated with TBBPS. The results have also revealed that tested compounds do not form adducts with DNA in PBMCs, while the observed changes were the most probably induced by indirect DNA-damaging agents, such as ROS and other reactive species.

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.

A review on environmental occurrence, toxic effects and transformation of man-made bromophenols

Brominated phenols (BPs) of anthropogenic origin are aromatic substances widely used in the industry as flame retardants (FRs) and pesticides as well as the components of FRs and polymers. In this review, we have focused on describing 2,4-dibromophenol (2,4-DBP), 2,4,6-tribromophenol (2,4,6-TBP) and pentabromophenol (PBP), which are the most commonly used in the industry and are the most often detected in the air, aquatic and terrestrial ecosystems and the human body. This review describes human-related sources of these BPs that influence their occurrence in the environment (atmosphere, surface water, sediment, soil, biota), indoor air and dust, food, drinking water and the human organism. Data from in vitro and in vivo studies showing 2,4-DBP, 2,4,6-TBP and PBP toxicity, including their estrogenic activity, effects on development and reproduction, perturbations of cellular redox balance and cytotoxic action have been described. Moreover, the processes of BPs transformation that occur in human and other mammals, plants and bacteria have been discussed. Finally, the effect of abiotic factors (e.g. UV irradiation and temperature) on BPs conversion to highly toxic brominated dioxins and brominated furans as well as polybrominated biphenyls and polybrominated diphenyl ethers has been presented.

Embryotoxic effects of tribromophenol on early post-implantation development of mouse embryos in vitro

2,4,6-Tribromophenol (TBP, CAS No. 118-79-6), the most widely produced brominated phenol, is frequently detected in environmental components. The detection of TBP in human bodies has earned great concerns about its adverse effects on human beings, especially for early embryonic development. Here, we optimized the mouse embryo in vitro culture (IVC) system for early post-implantation embryos and employed it to determine the embryotoxicity of TBP. With this new research model, we revealed the dose-dependent toxic effects of TBP on mouse embryos from peri-implantation to egg cylinder stages. Furthermore, TBP exposure inhibited the differentiation and survival of epiblast (EPI) cells and extraembryonic endoderm (ExEn) cells, while those of extraembryonic ectoderm (ExEc) cells were not influenced. These results implied that TBP might inhibit embryonic development by influencing the generation of three primary germ layers and fetal membranes (the amnion, chorionic disk, umbilical cord, and yolk sac). In summary, we showed a proof of concept for applying mouse embryo IVC system as a novel research model for studying mammalian embryonic toxicology of environmental pollutants. This study also demonstrated the toxicity of TBP on early embryonic development of mammals.

Urinary Volatomic Expression Pattern: Paving the Way for Identification of Potential Candidate Biosignatures for Lung Cancer

The urinary volatomic profiling of Indian cohorts composed of 28 lung cancer (LC) patients and 27 healthy subjects (control group, CTRL) was established using headspace solid phase microextraction technique combined with gas chromatography mass spectrometry methodology as a powerful approach to identify urinary volatile organic metabolites (uVOMs) to discriminate among LC patients from CTRL. Overall, 147 VOMs of several chemistries were identified in the intervention groups-including naphthalene derivatives, phenols, and organosulphurs-augmented in the LC group. In contrast, benzene and terpenic derivatives were found to be more prevalent in the CTRL group. The volatomic data obtained were processed using advanced statistical analysis, namely partial least square discriminative analysis (PLS-DA), support vector machine (SVM), random forest (RF), and multilayer perceptron (MLP) methods. This resulted in the identification of nine uVOMs with a higher potential to discriminate LC patients from CTRL subjects. These were furan, o-cymene, furfural, linalool oxide, viridiflorene, 2-bromo-phenol, tricyclazole, 4-methyl-phenol, and 1-(4-hydroxy-3,5-di-tert-butylphenyl)-2-methyl-3-morpholinopropan-1-one. The metabolic pathway analysis of the data obtained identified several altered biochemical pathways in LC mainly affecting glycolysis/gluconeogenesis, pyruvate metabolism, and fatty acid biosynthesis. Moreover, acetate and octanoic, decanoic, and dodecanoic fatty acids were identified as the key metabolites responsible for such deregulation. Furthermore, studies involving larger cohorts of LC patients would allow us to consolidate the data obtained and challenge the potential of the uVOMs as candidate biomarkers for LC.

Oxidative degradation of 2,4,6-tribromophenol by SBA-15 supported metal tetrakis(1-methylpyridinium-4-yl)porphyrins in the presence of humic substances

Metal tetrakis(1-methylpyridinium-4-yl)porphyrins were immobilized on sulfonated SBA-15 (MTMPyP-SO₃-pr-SBA-15, M = Fe, Mn, Zn) for oxidative degradation of 2,4,6-tribromophenol in the presence of humic substances. The influence of the central metal of metalloporphyrins, pH, and catalyst dosage on the 2,4,6-tribromophenol degradation was investigated. FeTMPyP-SO₃-pr-SBA-15 and MnTMPyP-SO₃-pr-SBA-15 showed the catalytic activities. The activity of MnTMPyP-SO₃-pr-SBA-15 was more strongly inhibited by humic substances than that of FeTMPyP-SO₃-pr-SBA-15. Kinetic study indicated that humic substances suppressed the generation of high valent metal-oxo species in MnTMPyP-SO₃-pr-SBA-15 at slightly acid condition. There was a clear linear relationship between the content of phenolic-OH and aromatic-C in humic substances and the corresponding inhibition ability. The inhibition by humic substances is probably ascribed to the coordination of humic substances with the monopersulfate species of MnTMPyP-SO₃-pr-SBA-15, which prevented the formation of the reactive Mn-oxo species.

2,4,6-Tribromophenol is toxic to Oreochromis niloticus (Linnaeus, 1758) after trophic and subchronic exposure

The presence of 2,4,6-Tribromophenol (TBP) in the environment increased the risk of exposure to aquatic organisms affecting the animal development or metabolism. The current study investigated the low, subchronic and trophic effect of TBP in both, male and female adult of Oreochromis niloticus. The fish were exposed to 0.5 or 50 ng g^-1 of TBP every ten days for 70 days. Then, hepatosomatic (HSI) and gonadosomatic (GSI) indexes, erythrocyte parameters (hemoglobin content, nuclear morphology and morphometrical abnormalities), biochemical endpoints (glutathione S-Transferase and catalase activities, non-protein thiols, lipid peroxidation and protein carbonylation levels in the liver; and acetylcholinesterase activity in the brain and muscle), histopathological analysis (liver) and vitellogenin levels (plasma) were considered. TBP affected the HSI in male and female fish, but not the GSI. Principal Component Analysis revealed that erythrocytes from males are more sensitive to TBP exposure. Likewise, TBP induced the expression of vitellogenin, CAT activity and liver lesion in male fish comparatively with control group, but GST and NPT were influenced only by sex. Finally, the results showed that the antioxidant mechanism and cholinesterase activity effects were more pronounced in male than in female. The current data shows evidences of estrogenic endocrine disruption and toxicity in O. niloticus exposed to TBP, revealing the risk of exposure to biota.

Bioconcentration of 2,4,6-tribromophenol (TBP) and thyroid endocrine disruption in zebrafish larvae

2,4,6-tribromophenol (TBP) is generally used as a brominated flame retardant but is produced in the degradation of tetrabromobisphenol-A. Although TBP is frequently detected in the environment and in various biota, including fish species, we still know little about its toxicity and environmental health risk. Here we investigated the bioconcentration and effects of TBP on the thyroid endocrine system by using zebrafish as a model. Zebrafish embryos (2 h post-fertilization, hpf) were exposed to five concentrations of TBP (0, 0.3, 1, 10, and 100 μg/L) until 144 hpf. According to our chemical analysis, TBP underwent bioconcentration in zebrafish larvae. However, acute exposure to TBP did not affect the hatching of embryos or their risk of malformation, nor the growth and survival of larvae, indicating low developmental toxicity of TBP. The whole-body thyroxine (T4) contents were significantly increased in zebrafish larvae after exposure to TBP, indicating thyroid endocrine disruption occurred. Gene transcription levels in the hypothalamic-pituitary-thyroid (HPT) axis were also examined in larvae; these results revealed that the transcription of corticotrophin-releasing hormone (crh), thyrotropin-releasing hormone (trh), and thyroid-stimulating hormone (tshβ) were all significantly downregulated by exposure to TBP. Likewise, genes encoding thyronine deiodinases (dio1, dio2, and dio3a/b) and thyroid hormone receptors (trα and trβ) also had their transcription downregulated in zebrafish. Further, the gene transcription and protein expression of binding and transport protein transthyretin (TTR) were significantly increased after TBP exposure. Taken together, our results suggest the bioavailability of and potential thyroid endocrine disruption by TBP in fish.

Tetrabromobisphenol A, terabromobisphenol S and other bromophenolic flame retardants cause cytotoxic effects and induce oxidative stress in human peripheral blood mononuclear cells (in vitro study)

Brominated flame retardants (BFRs) are the compounds used in the industry in order to decrease flammability of various everyday products. The use of BFRs leads to migration of these substances into the environment, which results in the exposure of humans to their action. Although BFRs are widespread in human surrounding, the effect of these compounds on human body has been very poorly assessed. The purpose of this study was to evaluate cytotoxic effects as well as oxidative potential of selected bromophenolic flame retardants such as tetrabromobisphenol A (TBBPA), tetrabromobisphenol S (TBBPS), 2,4,6-tribromophenol (2,4,6-TBP) and pentabromophenol (PBP) on human peripheral blood mononuclear cells (PBMCs) that are crucial for proper functioning of the immune system. The cells were treated with the substances studied in the concentrations ranging from 0.0001 to 100 μg/mL for 1 h or 24 h. The results have shown that the compounds examined reduced PBMCs viability and ATP level as well as increased reactive oxygen species (including hydroxyl radical) formation. Moreover, the substances tested induced lipid peroxidation and caused oxidative damage to proteins in the incubated cells. It has also been noticed that the greatest changes were provoked by tetrabromobisphenol A, while the weakest by TBBPS, which is used as a substitute of TBBPA in the manufacture.

Inhibition of UDP-glucuronosyltransferases (UGTs) by bromophenols (BPs)

Bromophenols (BPs) are important organic compounds which have become dominant pollutants during these years. Our present study investigated the potential inhibition behaviour of BPs on the activity of one of the most important phase II drug-metabolizing enzymes (DMEs), UDP-glucuronosyltransferases (UGTs). Recombinant UDP-glucuronosyltransferases (UGTs)-catalyzed glucuronidation of 4-methylumbelliferone (4-MU) was utilized as the probe reaction. 100 μM of BPs was utilized as the inhibition screening concentrations, and the complete inhibition profile of UGT isoforms by BPs was obtained. UGT1A7 was the most vulnerable UGT isoform towards BPs. Some structure-activity relationship for the inhibition of UGTs by BPs was found, and this relationship can be furtherly explained by the hydrophobic contacts of BPs with the activity cavity of UGTs using in silico docking method. The inhibition kinetics determination showed that the inhibition kinetic parameter K_i value was calculated to be 2.85, 3.99 and 31.00 μM for the inhibition of UGT1A3, UGT1A7, and UGT2B7 by representative BPs, 2,4,6-TBP. Combined with in vivo exposure concentration of 2,4,6-TBP, in vitro-in vivo extrapolation (IVIVE) was employed to demonstrate the moderate possibility for the inhibition of UGT1A3 and UGT1A7 by 2,4,6-TBP. In conclusion, our study gave the full description towards the inhibition of BPs towards UGT isoforms, which will provide a new perspective for elucidating the toxicity mechanism of bromophenols (BPs).

Changes in the activities of antioxidant enzymes and reduced glutathione level in human erythrocytes exposed to selected brominated flame retardants

Currently, more and more concerns are related to oxidative stress appearing in cells as a result of xenobiotics action. It has been found that selected brominated flame retardants (BFRs) can cause reactive oxygen species (ROS) induction at environmental concentrations. Excessive ROS induction can contribute to the redox imbalance in the cell. Therefore, the aim of our work was to evaluate the effect of selected BFRs on the activity of antioxidant enzymes, i.e. superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and the level of reduced glutathione (GSH) in human erythrocytes. Erythrocytes were incubated with tetrabromobisphenol A (TBBPA), tetrabromobisphenol S (TBBPS), 2,4-dibromophenol (2,4-DBP), 2,4,6-tribromophenol (2,4,6-TBP) and pentabromophenol (PBP) in the concentration ranging from 1 to 100 μg/ml. This study has shown that the BFRs studied disturbed redox balance in human erythrocytes. TBBPA caused more significant decrease in antioxidant enzymes activities than other compounds examined. Among bromophenols studied, 2,4-DBP most strongly affected antioxidant system, which indicated that the number of bromine atoms in the molecule did not significantly affect the pro-oxidative properties of the BFRs examined.

Distribution of the parent compound and its metabolites in serum, urine, and feces of mice administered 2,2',4,4'-tetrabromodiphenyl ether

2,2',4,4'-Tetrabromodiphenyl ether (BDE-47) is a predominant polybromodiphenyl ether congener in the environment. Its absorption, excretion, and metabolism in animals have been investigated; however, the distribution of BDE-47 and its metabolites in excreta and blood at steady-state conditions has been unclear. In the present study, we addressed the issue by determining the amounts of BDE-47, eight monohydroxylated metabolites (OH-BDEs), and 2,4-dibromophenol (2,4-DBP) in serum, urine, and feces of gpt delta transgenic mice orally administered BDE-47 at 1.5, 10, and 30 mg/kg/d for 6 weeks during the 24 h period (for urine and feces) or at 24 h (for blood) post-last dosing. The distribution profiles in the three matrices showed that BDE-47, OH-BDEs, and 2,4-DBP were mostly distributed in urine (59-70%), feces (95-96%), and urine (51-80%), respectively. In each matrix, BDE-47 was the predominant compound under all doses, which accounted for 84-96% in serum, 68-98% in urine, and 37-92% in feces. However, exclusive of BDE-47, OH-BDEs were the predominant class of metabolites in serum (72-86%) and feces (67-87%), whereas 2,4-DBP was the major metabolite in urine (98-99%). Among monohydroxylated metabolites, the dominant compounds were 4-hydroxy-2,2',3,4'-tetrabromodiphenyl ether (4-OH-BDE-42) and 4'-hydroxy-2,2',4,5'-tetrabromodiphenyl ether (4'-OH-BDE-49) in feces (27-33% and 25-43%, respectively), and 3-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (3-OH-BDE-47) in serum (26-43%). Thus, BDE-47 and 2,4-DBP were mostly present in urine, and OH-BDEs were primarily found in feces. Blood was not an important carrier for either BDE-47 or its metabolites. The data provide information for distribution and elimination of BDE-47 and its metabolites in mice at steady-state conditions.

In vitro assessment of eryptotic potential of tetrabromobisphenol A and other bromophenolic flame retardants

Brominated flame retardants (BFRs) such as tetrabromobisphenol A (TBBPA) and tetrabromobisphenol S (TBBPS) as well as bromophenols, i.e. 2,4-dibromophenol (2,4-DBP), 2,4,6-tribromophenol (2,4,6-TBP) and pentabromophenol (PBP) have raised wide concerns due to their widespread occurrence in the environment and adverse effects observed in living organisms including human. The effect of BFRs on apoptosis of human erythrocytes has not been examined, that is why we have decided to assess eryptotic potential of these substances by determining changes in phosphatidylserine (PS) translocation, alterations in intracellular ROS and calcium ion levels, as well as caspase-3 and calpain activation in this cell type. It has been found that all BFRs studied even in the concentration of 0.001 μg/mL induced ROS formation. The compounds examined caused apoptosis by PS externalization and caspase-3 activation in human red blood cells. It has also been shown that calcium ions and calpain did not play a significant role in eryptosis induction by BFRs studied in human erythrocytes.

Determination of dihalobenzoquinones in water using gas chromatography coupled with an electronic capture detector

Dihalobenzoquinones are a group of disinfection byproducts with high potential toxicity and thus currently receiving increased attention. A determination method of 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ) and 2,6-dibromo-1,4-benzoquinone (2,6-DBBQ) was developed upon using liquid-liquid extraction and a gas chromatography with an electronic capture detector (LLE-GC-ECD). The optimized extraction condition was as the following: volume ratio of formic acid to water 0.005%, Na₂SO₄ dosage 200 g L^-1, methyl-tert-butyl ether (MtBE)/water volume ratio 1/10, and extraction with MtBE for once. With the dosed concentrations of 0.5-5.0 μg L^-1, the recovery rates of 2,6-DCBQ and 2,6-DBBQ were 81%-88% and 73%-96%. The limits of quantitation (LOQs) of the LLE-GC-ECD method were 2.4 and 2.7 ng L^-1 in 1-L water for 2,6-DCBQ and 2,6-DBBQ. In six local tap waters, 2,6-DCBQ was detected in the range of <LOQ-20.5 ng L^-1 and no 2,6-DBBQ was detected. The method is recommended for low-cost and rapid determination of 2,6-DCBQ and 2,6-DBBQ in water.

Disruption of thyroid hormone levels by decabrominated diphenyl ethers (BDE-209) in occupational workers from a deca-BDE manufacturing plant

While there is some evidence that exposure to decabrominated diphenyl ethers (BDE-209) affects thyroid function, the results obtained to date have been inconsistent. No studies have been performed on workers in deca-BDE manufacturing who had a high level of exposure to BDE-209 and relatively little exposure to other contaminants. In the present study, the relationship between BDE-209 exposure and thyroid hormone in occupational workers from a deca-BDE manufacturing plant was investigated. The serum and urine levels of polybrominated diphenyl ethers (PBDEs) and serum thyroid hormones were measured in 72 workers recruited from the deca-BDE manufacturing plant. The associations between their thyroid hormone levels and their exposure to BDE-209 were examined using multiple linear regression models. Serum concentrations of BDE-209 ranged from 67.4 to 109,000 ng/g lipid weight (lw), with a median of 3420 ng/g lw, contributing to 93.1% of the total PBDEs. The concentration of BDE-209 in urine was highly correlated with that in the serum (r² = 0.440, p < 0.001), indicating that urine may be a good non-invasive biomonitoring medium of BDE-209 body burden in occupational workers. BDE-209 in the serum was significantly and positively correlated with total thyroxine (tT4, r = 0.270, p = 0.029) and marginally and positively correlated with total triiodothyronine (tT3, r = 0.232, p = 0.061) in all occupational workers after adjusting for gender, age, BMI, and occupational exposure duration. A 10-fold increase in the serum BDE-209 concentration was associated with an increase in tT4 (8.63 nmol/L) [95% confidence interval (CI): 0.930-16.3] and tT3 (0.106 nmol/L) [95% confidence interval (CI): -0.005-0.219], corresponding to the increase of 7.8% in tT4 level and 5.4% in tT3 level. Associations between urine BDE-209 levels and thyroid hormones were similar to the results for the serum levels. These findings offer new evidence for proving the thyroid disrupting effects of BDE-209, impacting the direction of hyperthyroidism.

Fast trace determination of nine odorant and estrogenic chloro- and bromo-phenolic compounds in real water samples through automated solid-phase extraction coupled with liquid chromatography tandem mass spectrometry

A fast and reliable method was developed for simultaneous trace determination of nine odorous and estrogenic chloro- and bromo-phenolic compounds (CPs and BPs) in water samples using solid-phase extraction (SPE) coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS). For sample preparation, the extraction efficiencies of two widely applied cartridges Oasis HLB and Sep-Pak C18 were compared, and the Oasis HLB cartridge showed much better extraction performance; pH of water sample also plays important role on extraction, and pH = 2-3 was found to be most appropriate. For separation of the target compounds, small addition of ammonium hydroxide can obviously improve the detection sensitivity, and the optimized addition concentration was determined as 0.2%. The developed efficient method was validated and showed excellent linearity (R ² > 0.995), low limit of detection (LOD, 1.9-6.2 ng/L), and good recovery efficiencies of 57-95% in surface and tap water with low relative standard deviation (RSD, 1.3-17.4%). The developed method was finally applied to one tap and one surface water samples and most of these nine targets were detected, but all of them were below their odor thresholds, and their estrogen equivalent (EEQ) were also very low.

Environmental concentrations and toxicology of 2,4,6-tribromophenol (TBP)

2,4,6-Tribromophenol is the most widely produced brominated phenol. In the present review, we summarize studies dealing with this substance from an environmental point of view. We cover concentrations in the abiotic and biotic environment including humans, toxicokinetics as well as toxicodynamics, and show gaps of the current knowledge about this chemical. 2,4,6-Tribomophenol occurs as an intermediate during the synthesis of brominated flame retardants and it similarly represents a degradation product of these substances. Moreover, it is used as a pesticide but also occurs as a natural product of some aquatic organisms. Due to its many sources, 2,4,6-tribromophenol is ubiquitously found in the environment. Nevertheless, not much is known about its toxicokinetics and toxicodynamics. It is also unclear which role the structural isomer 2,4,5-tribromophenol and several degradation products such as 2,4-dibromophenol play in the environment. Due to new flame retardants that enter the market and can degrade to 2,4,6-tribromophenol, this compound will remain relevant in future years - not only in aquatic matrices, but also in house dust and foodstuff, which are an important exposure route for humans.

Total organic halogen (TOX) in human urine: A halogen-specific method for human exposure studies

Disinfection by-products (DBPs) are a complex mixture of compounds unintentionally formed as a result of disinfection processes used to treat drinking water. Effects of long-term exposure to DBPs are mostly unknown and were the subject of recent epidemiological studies. However, most bioanalytical methods focus on a select few DBPs. In this study, a new comprehensive bioanalytical method has been developed that can quantify mixtures of organic halogenated compounds, including DBPs, in human urine as total organic chlorine (TOCl), total organic bromine (TOBr), and total organic iodine (TOI). The optimized method consists of urine dilution, adsorption to activated carbon, pyrolysis of activated carbon, absorption of gases in an aqueous solution, and halide analysis with ion chromatography and inductively coupled plasma-mass spectrometry. Spike recoveries for TOCl, TOBr, and TOI measurements ranged between 78% and 99%. Average TOCl, TOBr, and TOI concentrations in five urine samples from volunteers who consumed tap water were 1850, 82, and 21.0μg/L as X^-, respectively. Volunteers who consumed spring water (control) had TOCl, TOBr, and TOI average concentrations in urine of 1090, 88, and 10.3μg/L as X^-, respectively. TOCl and TOI in the urine samples from tap water consumers were higher than the control. However, TOBr was slightly lower in tap water urine samples compared to mineral water urine samples, indicating other sources of environmental exposure other than drinking water. A larger sample population that consumes tap water from different cities and mineral water is needed to determine TOCl, TOBr, and TOI exposure from drinking water.

Gas Purge Microextraction Coupled with Stable Isotope Labeling-Liquid Chromatography/Mass Spectrometry for the Analysis of Bromophenols in Aquatic Products

A green, sensitive, and accurate method was developed for the extraction and determination of bromophenols (BPs) from aquatic products by using organic solvent-free gas purge microsyringe extraction (GP-MSE) technique in combination with stable isotope labeling (SIL) strategy. BPs were extracted by NaHCO₃ buffer solution, with recoveries varying from 92.0% to 98.5%. The extracted solution was analyzed by SIL strategy, during which analytes and standards were labeled by 10-methyl-acridone-2-sulfonyl chloride (d₀-MASC) and its deuterated counterpart d₃-MASC, respectively. The labeling reaction was finished within 10 min with good stability. The liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) sensitivity of BPs was greatly enhanced due to the mass-enhancing property of MASC, while the matrix effect was effectively minimized by the SIL strategy. The limits of detection (LODs) were in the range of 0.10-0.30 μg/kg, while the limits of quantitations (LOQs) were in the range of 0.32-1.0 μg/kg. The proposed method also showed great potential in the qualitative analysis of other bromophenols in the absence of standard.