Evaluating effects of tetrabromobisphenol A and microplastics on anaerobic granular sludge: Physicochemical properties, microbial metabolism, and underlying mechanisms.

Tetrabromobisphenol A (TBBPA) and microplastics are emerging contaminants of widespread concern. However, little is known about the effects of combined exposure to TBBPA and microplastics on the physicochemical properties and microbial metabolism of anaerobic granular sludge. This study investigated the effects of TBBPA, polystyrene microplastics (PS MP) and polybutylene succinate microplastics (PBS MP) on the physicochemical properties, microbial communities and microbial metabolic levels of anaerobic granular sludge. The results showed that chemical oxygen demand (COD) removal of sludge was lowest in the presence of TBBPA alone and PS MP alone with 33.21% and 30.06%, respectively. The microorganisms promoted the secretion of humic substances under the influence of TBBPA, PS MP and PBS MP. The lowest proportion of genes controlling glycolytic metabolism in sludge was 1.52% when both TBBPA and PS MP were added. Microbial reactive oxygen species were increased in anaerobic granular sludge exposed to MPS. In addition, TBBPA treatment decreased electron transfer of the anaerobic granular sludge and disrupted the pathway of anaerobic microorganisms in acquiring adenosine triphosphate, and MPs attenuated the negative effects of TBBPA on the acetate methanogenesis process of the anaerobic granular sludge. This study provides a reference for evaluating the impact of multiple pollutants on anaerobic granular sludge.

Biotransformation and detoxification of tetrabromobisphenol A by white-rot fungus Phanerochaete sordida YK-624.

The bulky phenolic compound tetrabromobisphenol A (TBBPA) is a brominated flame retardant used in a wide range of products; however, it diffuses into the environment, and has been reported to have toxic effects. Although it is well-known that white-rot fungi degrade TBBPA through ligninolytic enzymes, no other metabolic enzymes have yet been identified, and the toxicity of the reaction products and their risks have not yet been examined. We found that the white-rot fungus Phanerochaete sordida YK-624 converted TBBPA to TBBPA-O-ß-D-glucopyranoside when grown under non-ligninolytic-enzyme-producing conditions. The metabolite showed less cytotoxicity and mitochondrial toxicity than TBBPA in neuroblastoma cells. From molecular biological and genetic engineering experiments, two P. sordida glycosyltransferases (PsGT1c and PsGT1e) that catalyze the glycosylation of TBBPA were newly identified; these enzymes showed dramatically different glycosylation activities for TBBPA and bisphenol A. The results of computational analyses indicated that the difference in substrate specificity is likely due to differences in the structure of the substrate-binding pocket. It appears that P. sordida YK-624 takes up TBBPA, and reduces its cytotoxicity via these glycosyltransferases.

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.

Persulfate activation with sodium alginate/sulfide coated iron nanoparticles for degradation of tetrabromobisphenol a in soil.

The accumulation of tetrabromobisphenol A (TBBPA) in soil posed a serious threat to ecosystem and human health. Sodium alginate/sulfide coated iron nanoparticles (SA@S-Fe NPs) was synthesized by a two-step modification of Fe NPs prepared with tung tree leaves extracting solution, and utilized as a persulfate (PS) activator to degrade TBBPA in soil. Response surface methodology (RSM) optimization showed a theoretical maximum TBBPA degradation reaching 99.79% at the 34.28 °C, SA@S-Fe NPs and PS additions of 3.57 g kg-1 and 36.35 mM, respectively. The degradation mechanism of TBBPA suggested that the main reactive species produced in the SA@S-Fe NPs/PS system were •OH, SO4•-, and O2•-. Proposed mechanisms for the degradation of TBBPA in soil involved debromination, benzene rings split, hydroxylation, demethylation, and complete mineralization to CO2 and H2O. We also further studied the effect to soil physicochemical properties and morphology structure during TBBPA degradation in SA@S-Fe NPs/PS system, which showed that SOM, TN, C/N and TOC slightly reduced, the heavy metals Fe, Cu and Zn still existed in stable residue form, and the soil morphology showed a certain degree of aggregation. Therefore SA@S-Fe NPs/PS technology can effectively degrade soil TBBPA, maintain soil fertility, curb the migration of heavy metals, and environmental risks.

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.

Theoretical study on pyrolysis mechanism of decabromodiphenyl ether (BDE-209) using DFT method.

Decabromodiphenyl ether (BDE-209), as a brominated flame retardant (BFR), is widely applied to various consumer products due to its superior performance and affordable pricing to improve the flame resistance of materials. To better comprehend the pyrolysis behavior of BDE-209 and the evolution process of main pyrolysis products, the thermal degradation mechanism of BDE-209 was studied using density functional theory (DFT) method at the theoretical level of M06/cc-pVDZ, and thermodynamic parameters were calculated in this paper. Unimolecular degradation was dominated by cleavage of the ether linkage, which results in a high yield of hexabromobenzene, and fission of the ortho-position C-Br bond is the main competitive reaction channel. In the system of BDE-209 + H, the pyrolysis reaction is majorly characterized by debromination, leading to the formation of considerable HBr and low-brominated diphenyl ethers. Additionally, the hydrogen-derived splitting of the ether bond acts as a mainly competitive channel, which is the source of polybromophenols and polybromobenzenes. The formation of polybrominated dibenzofuran (PBDF) derives from the cyclization reaction of ortho-phenyl-type radicals, which are readily generated through the ortho-position Br atom abstraction by H radical. The formation of polybrominated dibenzo-p-dioxin (PBDD) involves the ortho-C-O coupling reaction of polybromophenoxy radicals, debromination reaction, and cyclization reaction. And the total yield of PBDD/Fs was significantly increased when H was involved. Results presented in this work will provide the helpful information for the treatment and reuse of BDE-209-containing waste plastics through using pyrolysis technology.

Transcriptomic sequencing reveals the potential molecular mechanism by which Tetrabromobisphenol A bis (2-hydroxyethyl ether) exposure exerts developmental neurotoxicity in developing zebrafish (Danio rerio).

Tetrabromobisphenol A bis (2-hydroxyethyl ether) (TBBPA-DHEE) is a derivative of Tetrabromobisphenol A (TBBPA) used as an intermediate flame retardant in engineering polymers. The mechanism of neurodevelopmental toxicity of TBBPA-DHEE remains unclear due to limited toxicological data. We performed behavioral and transcriptomic analyses to assess the neurodevelopmental effects of TBBPA-DHEE on developing zebrafish and potential toxicity mechanisms. Our result shows that exposure to TBBPA-DHEE significantly increased mortality, deformity rate, and reduction in hatch rate, hatchability, and body length relative to the DMSO control. The behavior analysis indicates that TBBPA-DHEE significantly reduced the spontaneous movement of larva compared to the control. The TSH and GH levels were significantly reduced in all the exposure groups in a concentration-dependent manner relative to the DMSO control. TBBPA-DHEE exhibited a significant reduction in locomotor activity across all the exposure groups in the light/dark locomotion test. The transcriptomic analysis result shows that 579 genes were differentially expressed. KEGG analysis shows the enrichment of complement cascade, JAK-STAT signaling pathway, cytokine-cytokine interaction, and phototransduction pathway resulting in a change in mRNA expression of their genes. These observed changes in developmental endpoints, hormonal level, and alteration in mRNA expression of component genes involved in neurodevelopmental pathways could be part of the possible mechanism of the observed toxic effects of TBBPA-DHEE exposure on zebrafish. This study could reveal the possible neurodevelopmental toxicity of TBBPA-DHEE to aquatic species, which could help uncover the health implications of emerging environmental contaminants.

Studies on the characteristics and mechanism of aerobic biodegradation of tetrabromobisphenol A by Irpex lacteus F17.

The study investigated the characteristics of aerobic degradation of tetrabromobisphenol A (TBBPA) by Irpex lacteus F17 (I. lacteus F17) under four different cometabolic substrates (phenol, glucose, sodium pyruvate, and sodium citrate). The biodegradation of TBBPA by I. lacteus F17 could be enhanced via cometabolism, and glucose (8 g/L) was confirmed to be the optimum carbon source. For different initial solution pH ranging from 3.0 to 8.0, the results showed that I. lacteus F17 could be applied to biodegrade TBBPA in a wide pH range of 4.0-8.0, and the degradation rate could reach the maximum 75.31%, while the debromination rate reached the maximum 12.40% under pH 5.0. In addition, it has been confirmed that Mn2+ (50 µmol/L) could promote the secretion of manganese peroxidase and TBBPA biodegradation efficiency. Seven intermediates were identified by gas chromatography-mass spectrometry analysis, and the possible degradation pathways were proposed, which indicated the biodegradation of TBBPA might be subjected to debromination, ß-scission, hydroxylation, deprotonation, and oxidation reactions.

Racial/ethnic and geographic differences in polybrominated diphenyl ether (PBDE) levels across maternal, placental, and fetal tissues during mid-gestation.

Prenatal polybrominated diphenyl ether (PBDE) exposures are a public health concern due to their persistence and potential for reproductive and developmental harm. However, we have little information about the extent of fetal exposures during critical developmental periods and the variation in exposures for groups that may be more highly exposed, such as communities of color and lower socioeconomic status (SES). To characterize maternal-fetal PBDE exposures among potentially vulnerable groups, PBDE levels were examined in the largest sample of matched maternal serum, placenta, and fetal liver tissues during mid-gestation among a geographically, racially/ethnically, and socially diverse population of pregnant women from Northern California and the Central Valley (n = 180; 2014-16). Maternal-fetal PBDE levels were compared to population characteristics using censored Kendall's tau correlation and linear regression. PBDEs were commonly detected in all biomatrices. Before lipid adjustment, wet-weight levels of all four PBDE congeners were highest in the fetal liver (p < 0.001), whereas median PBDE levels were significantly higher in maternal serum than in the fetal liver or placenta after lipid-adjustment (p < 0.001). We also found evidence of racial/ethnic disparities in PBDE exposures (Non-Hispanic Black > Latina/Hispanic > Non-Hispanic White > Asian/Pacific Islander/Other; p < 0.01), with higher levels of BDE-100 and BDE-153 among non-Hispanic Black women compared to the referent group (Latina/Hispanic women). In addition, participants living in Fresno/South Central Valley had 34% (95% CI: - 2.4 to 84%, p = 0.07) higher wet-weight levels of BDE-47 than residents living in the San Francisco Bay Area. PBDEs are widely detected and differentially distributed in maternal-fetal compartments. Non-Hispanic Black pregnant women and women from Southern Central Valley geographical populations may be more highly exposed to PBDEs. Further research is needed to identify sources that may be contributing to differential exposures and associated health risks among these vulnerable populations.

Structural binding interactions of tetrabromobisphenol A with sex steroid nuclear receptors and sex hormone-binding globulin.

Tetrabromobisphenol A (TBBPA) is a widely used brominated flame retardant owing to its efficient fire-breaking property. However, leaching of TBBPA into the environment has been a global health concern due to the endocrine-disrupting activity (EDA) associated with TBBPA exposure. Limited studies are available on the hazardous effects of TBBPA on reproductive function. The aim of the present study was the structural characterization of potential EDA of TBBPA in reproductive hormone signaling and transport including steroid nuclear receptors, such as estrogen receptor alpha (ERα), estrogen receptor beta (ERß), androgen receptor (AR), progesterone receptor (PR), and the steroid transport protein, sex hormone-binding globulin (SHBG). The structural binding characterization of TBBPA with the sex steroid nuclear receptors and transport protein was performed by induced-fit docking using the Schrödinger 2017 suite. The results revealed that the TBBPA binding pattern and molecular interactions with the indicated receptors and transport protein displayed overall similarity with their respective native ligands. The estimated binding energy value of TBBPA for ERα was similar to the native ligand, estradiol, indicating tight binding and greater potential for TBBPA to disrupt ERα signaling. For ERß, AR, PR and SHBG, the estimated binding energy values were also close to their respective native ligands, indicating potential for interference in native hormone signaling and transport. In conclusion, TBBPA exposure in humans may potentially cause disruption of sex steroid signaling and transport, and thus lead to reproductive dysfunction.

Identification of novel pathways for biotransformation of tetrabromobisphenol A by Phanerochaete chrysosporium, combined with mechanism analysis at proteome level.

The investigation of tetrabromobisphenol A (TBBPA) removal by Phanerochaete chrysosporium (P. chrysosporium) was conducted. Under optimal conditions (pH 5, inoculum size of 5% (v/v), initial glucose concentration of 5 g/L, TBBPA concentration of 5 mg/L), >97% of initial TBBPA was removed after 3 days. The TBBPA metabolites, tetrabromobisphenol A glycoside, tribromobisphenol A glycoside and monohydroxylated tetrabromobisphenol A, were identified for the first time by fungi transformation as being produced by glycosylation and oxidative hydroxylation, respectively. Proteome analysis showed that P. chrysosporium significantly upregulated cytochrome P450 monooxygenase, glutathione S-transferases, UDP-glucosyltransferase, O­methyltransferase and other oxidoreductases for TBBPA oxidative hydroxylation, reductive debromination, glycosylation, O­methylation and oxidative cleavage for detoxification. Data from cytotoxicity tests with human hepatocellular liver carcinoma (HepG2) confirmed that TBBPA toxicity was effectively decreased by P. chrysosporium treatment. Bioaugmentation with P. chrysosporium significantly improved the removal efficiency of TBBPA in water microcosms to 63.1% within 12 h. This study suggests that P. chrysosporium might be suitable for the removal of TBBPA from contaminated water.

Anaerobic degradation of deca-brominated diphenyl ether contaminated in products: Effect of temperature on degradation characteristics.

In this study, a 200-day deca-brominated diphenyl ether (deca-BDE) degradation activity experiment was carried out, using consumer-use curtain material as the substrate. During the degradation process, polybrominated diphenyl ether (PBDE) products with fewer bromine atoms were gradually generated by the debromination of deca-BDE. The influences of temperature, initial substrate dosing mass, and pH were also investigated. Interestingly, thermophilic conditions proved more beneficial for deca-BDE degradation than mesophilic conditions. The results also demonstrate that the debromination rate increased with the initial deca-BDE dosing mass, and that pH 7 was the most suitable for the reaction.

Tissue distribution of tetrabromobisphenol A and cadmium in mixture inhalation exposure.

Tetrabromobisphenol A (TBBPA) and cadmium chloride (CdCl2) are the typical representative pollutants of brominated flame retardants and heavy metals found in the air of e-waste recycling workshops. However, their metabolic kinetics through mixture inhalation is unknown. In the present study, 8-week old Institute of Cancer Research (ICR) male mice were whole-body exposed to TBBPA and CdCl2 mixtures by inhalation. Tissue samples were collected for TBBPA and cadmium (Cd) analysis at 2, 4, 6, and 8 weeks during exposure and at 4 and 8 weeks after the completion of the 8-week exposure period. TBBPA was mainly distributed to the lungs, liver, kidney, testis, and spleen, with a high amount accumulated in the brain, liver, and spleen. Cd was mainly distributed to the lungs, liver, and kidney, with a high amount accumulated in the liver, kidney, and testis and a low amount accumulated in brain and serum. Tissue burden of TBBPA and Cd in all organs increased in a dose- and time-dependent manner during the exposure period. However, 4 weeks after the completion of an 8-week exposure, TBBPA concentrations in the liver, testis, brain, and serum and Cd concentrations in the liver, testis, and kidney were higher than the corresponding tissue concentrations during the exposure period. The rapid accumulation of both TBBPA and Cd in the lungs after inhalation exposure indicated a high risk of the respiratory system diseases for workers in e-waste recycling workshops. In addition, the migration of both TBBPA and Cd from lungs to liver and testis may result in more complex toxic effects in vivo.

Species-dependent effects of earthworms on the fates and bioavailability of tetrabromobisphenol A and cadmium coexisted in soils.

The activity of e-waste recycling often causes the combined pollution of tetrabromobisphenol A (TBBPA) and cadmium (Cd) in soils. In this study, the effects of their co-existence on each other's fate, further reflecting the bioavailability, were analyzed in the presence of two ecologically different earthworm species, endogeic Metaphire guillelmi and epigeic Eisenia fetida. Mineralization of 14C-TBBPA combined with 10 mg Cd kg-1 was suppressed by the presence of M. guillelmi, whereas a facilitating effect was produced by the combination of 1 mg Cd kg-1 in the soil-E. fetida system after a 14-day exposure. The uptake of 14C-TBBPA by M. guillelmi (17% of initial amount) and by E. fetida (10%) dominantly contributed to significant (P < 0.05) decrease of extractable (more bioavailable) 14C residues in soils both with and without Cd spiked, while the mineralization of 14C-TBBPA in the soils was negligible (<0.4%). Meanwhile the amendments of the two earthworm species exerted different impact on 14C distribution in bound residues. In general, co-exposure to Cd did not significantly (P > 0.05) influence the accumulation and metabolism of TBBPA in the earthworms. Both earthworms accumulated only ~7% of Cd in soil, however, the bioavailable Cd determined by the diffusive gradients in thin films technique declined by ~46% in the presence of M. guillelmi, and a much smaller decrease was determined in the presence of E. fetida. Amendment of TBBPA at environmental levels did not alter the accumulation and subcellular distribution of Cd in both earthworms unless that at high doses. The results highlighted the importance of considering the difference of the earthworm species and the interaction of pollutants in soil-risk assessments of such combined contamination. CAPSULE: M. guillelmi displayed greater effect on the fate of TBBPA and Cd co-existed in soils than E. fetida, while the accumulation, metabolism, or distribution of the two pollutants in earthworms did not significantly alter due to interactions between the two pollutants.

Effects of biochar on 2, 2', 4, 4', 5, 5'-hexabrominated diphenyl ether (BDE-153) fate in Amaranthus mangostanus L.: Accumulation, metabolite formation, and physiological response.

The accumulation and metabolism of 2, 2', 4, 4', 5, 5'-hexabrominated diphenyl ether (BDE-153) in Amaranthus mangostanus L. (amaranth) as affected by different concentrations of biochar (1.3 to 26.6 g/L) under hydroponic conditions exposed to 10 µg/L BDE-153 after 10 days were investigated. Biochar significantly reduced BDE-153 shoot and root content by 27.5-61.6% and 73-95.3%, respectively. In general, BDE-153 migration from solution to amaranth decreased with increasing the doses of biochar. BDE-153 metabolites altered with doses of biochar. The ratio of de-BDEs to BDE-153 in root was polynomial correlated to biochar dose (R2 = 0.9356**). Root and shoot Fe content was positively correlated with the BDE-153 amounts (R2 = 0.948** and 0.822*, respectively). Though the higher biochar dose could obviously control BDE-153 uptake by the vegetable, the toxicity was caused more significantly. For instances, the high concentration of biochar at 26.6 g/L reduced pigment content, increased total ROS, and elevated antioxidant enzyme activity. At the same time, the O2- intensity was linearly positively correlated with de-BDEs in root (R2 = 0.7324*) while photosynthetic parameter Fv/fm intensity was polynomial correlated to BDEs in shoot (R2 = 0.9366*). Transmission electron microscopy (TEM) confirmed that exposure to BDE-153 and high concentration biochar at 26.6 g/L severely altered the chloroplasts in terms of the organelle shape and the presence of starch granules in the chloroplast. Taken together, biochar as a soil amendment could significantly control BDE-153 uptake and enhance BDE-153 metabolism in vegetables, but considering the dose of biochar to avoid its toxicity with higher dose.

Utilizing ion mobility spectrometry and mass spectrometry for the analysis of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polybrominated diphenyl ethers and their metabolites.

Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are persistent environmental pollutants originating from incomplete combustion of organic materials and synthetic sources. PAHs, PCBs, and PBDEs have all been shown to have a significant effect on human health with correlations to cancer and other diseases. Therefore, measuring the presence of these xenobiotics in the environment and human body is imperative for assessing their health risks. To date, their analyses require both gas chromatography and liquid chromatography separations in conjunction with mass spectrometry measurements for detection of both the parent molecules and their hydroxylated metabolites, making their studies extremely time consuming. In this work, we characterized PAHs, PCBs, PBDEs and their hydroxylated metabolites using ion mobility spectrometry coupled with mass spectrometry (IMS-MS) and in combination with different ionization methods including electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI). The collision cross section and m/z trend lines derived from the IMS-MS analyses displayed distinct trends for each molecule type. Additionally, the rapid isomeric and molecular separations possible with IMS-MS showed great promise for quickly distinguishing the parent and metabolized PAH, PCB, and PDBE molecules in complex environmental and biological samples.

Biotransformation of tetrabromobisphenol A dimethyl ether back to tetrabromobisphenol A in whole pumpkin plants.

As the metabolites of tetrabromobisphenol A (TBBPA), tetrabromobisphenol A mono- and di-methyl ethers (TBBPA MME and TBBPA DME) have been detected in various environmental media. However, knowledge of the contribution of plants to their environmental fates, especially to the interactions between TBBPA DME and TBBPA, is quite limited. In this study, the metabolism and behaviors of TBBPA DME was studied with pumpkin plants through 15-day hydroponic exposure. The TBBPA were also studied separately using in-lab hydroponic exposure for comparison. The results showed that more TBBPA DME accumulated in pumpkin roots and translocated up to stems and leaves compared with TBBPA. Transformation of TBBPA DME occurred later and more slowly than that of TBBPA. Interconversion between TBBPA DME and TBBPA was verified in intact plants for the first time. Namely, TBBPA DME can be biotransformed to TBBPA MME (transformation ratio in mole mass, TRMM 0.50%) and to TBBPA (TRMM 0.53%) within pumpkin; and TBBPA can be biotransformed to TBBPA MME (TRMM 0.58%) and to TBBPA DME (TRMM 0.62%). In addition, two single benzene-ring metabolites, 2,6-dibromo-4-(2-(2-hydroxyl)-propyl)-anisole (DBHPA, TRMM 3.4%) with an O-methyl group and 2,6-dibromo-4-(2-(2-hydroxyl)-propyl)-phenetole (DBHPP, TRMM 0.57%) with an O-ethyl group, were identified as the transformation products in the TBBPA exposure experiments. The transformation and interconversion from TBBPA DME back to TBBPA is reported as a new pathway and potential source for TBBPA in the environment.

Oxidative stress and renal toxicity after subacute exposure to decabrominated diphenyl ether in Wistar rats.

Fully brominated diphenyl ether (BDE-209) is a flame retardant widely used in plastics and textiles. Because of its high persistence, humans are exposed to it continuously, mainly via dust ingestion. We investigated effects of BDE-209 on renal function and oxidative stress development in the kidney after subacute exposure in rats. Five groups of animals were given by oral gavage 31.25-500 mg BDE-209/kg b.w./day for 28 days, and relative kidney weight, serum urea and creatinine, and oxidative stress parameters in the kidney were determined. Benchmark-dose approach was used for dose response modeling. Serum creatinine was increased, while results obtained for serum urea were inconclusive. Relative kidney weight was not affected by BDE-209. Kidney reduced glutathione was elevated, while superoxide dismutase activity was not changed after BDE-209 treatment. Also, levels of thiobarbituric acid reactive substances (TBARS) were increased and total -SH groups were decreased, which indicated oxidative imbalance. The critical effect dose (CED)/CEDL ratios for the effects on TBARS and total -SH groups indicated estimated CEDs for these markers can be used in risk assessment of BDE-209. Our study results have shown that a relatively low dose of BDE-209 affects kidney function and that oxidative stress is one of the mechanisms of its nephrotoxicity.

Current-use flame retardants: Maternal exposure and neurodevelopment in children of the CHAMACOS cohort.

Flame retardants are commonly used in consumer products found in U.S. households. Restrictions on the use of polybrominated diphenyl ether flame retardants have resulted in increased use of replacement chemicals, including Firemaster 550® (FM 550®) and organophosphate flame retardants (PFRs): tris(1,3- dichloro-2-propyl) phosphate (TDCIPP); tris(chloropropyl) phosphate (TCIPP); tris(2-chloroethyl) phosphate (TCEP); and triphenyl phosphate (TPHP). Animal research suggests that PFRs may affect neurodevelopment through noncholinergic mechanisms similar to some organophosphate (OP) pesticides. Despite the widespread presence of these compounds in home environments, and their structural similarity to neurotoxic OP pesticides, understanding of human exposure and health effects of PFRs is limited. We measured four urinary PFR metabolites from pregnant women in the CHAMACOS birth cohort study (n = 310) and assessed neurodevelopment of their children at age 7. Metabolites of TDCIPP (BDCIPP: bis(1,3-dichloro-2-propyl) phosphate) and TPHP (DPHP: diphenyl phosphate) were detected in >75% of urine samples, and isopropylphenyl phenyl phosphate (ip-PPP), a metabolite of one component of FM 550®, was detected in 72% of urine samples. We observed decreases of 2.9 points (95% Confidence Interval (CI): -6.3, 0.5) and 3.9 points (95% CI: -7.3,-0.5) in Full-Scale intelligence quotient and Working Memory, respectively, for each ten-fold increase in DPHP in adjusted regression models (n = 248). Decreases in Full-Scale IQ and Working Memory were greater in models of the molar sum of the PFR metabolites compared to the DPHP models. This is the first study to examine PFR and FM 550® exposures and potential neurodevelopmental outcomes in pregnant women and children. Additional research is warranted.

Intake, distribution, and metabolism of decabromodiphenyl ether and its main metabolites in chickens and implications for human dietary exposure.

Diet is considered as the most important human exposure pathway for polybrominated diphenyl ethers (PBDEs). Metabolism and accumulation patterns of PBDEs in different growth periods of chickens are helpful for evaluating human dietary exposure, but such information is scarce. In this study, female chickens were fed with food spiked with BDE-209 at 85 mg kg-1, and the intake, accumulation, and excretion of BDE-209 and its main metabolites in various tissues were examined. Concentrations of BDE-209 in chicken tissues increased over time in a tissue-specific manner; they were the greatest in liver and generally the lowest in breast meat during the entire exposure period. The kinetic patterns were dependent on both growth-dilution effects and accumulated concentrations of BDE-209. Tissue concentrations of ∑8PBDE (sum of BDE-28, 47, 99, 100, 153, 154, 183, and 209) followed the sequence of liver > blood > skin > intestine > stomach > leg meat > breast meat. Different tissue partition coefficients and perfusion rates for blood may have resulted in different PBDE concentrations in tissues. The absorption efficiency of BDE-209 in chicken tissues followed the sequence of liver (0.15 ± 0.032%) > skin (0.14 ± 0.038%) > intestine (0.071 ± 0.021%) > breast meat (0.062 ± 0.020%) > leg meat (0.059 ± 0.016%) > stomach (0.021 ± 0.0095%), likely due in part to facilitated absorption of BDE-209 by transport proteins (P-glycoproteins). On average, 9.3 ± 1.7% of BDE-209 was excreted in feces. Estimated human average dietary intake via the consumption of chicken tissues of ∑8PBDE for adults and children was 319 and 1380 ng day-1 for liver, 211 and 632 ng day-1 for leg meat, and 104 and 311 ng day-1 for breast meat from the contaminated group. Liver clearly poses the highest exposure risk for human consumption, particularly if chickens are fed with contaminated feed.