Disposition of the Emerging Brominated Flame Retardant, 2-Ethylhexyl 2,3,4,5-Tetrabromobenzoate, in Female SD Rats and Male B6C3F1 Mice: Effects of Dose, Route, and Repeated Administration.
ABSTRACT: 2-Ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB; MW 549.92?g/mol; CAS 183658-27-7) is a brominated component of flame retardant mixtures used as substitutes for some PBDEs. EH-TBB is added to various consumer products, including polyurethane foams, and has been detected in humans. The present study characterized the fate of EH-TBB in rodents. [14C]-labeled EH-TBB was absorbed, metabolized, and eliminated via the urine and feces following single administrations of 0.1-100 µmol/kg (?0.05-55?mg/kg) or repeated administration (0.1 µmol/kg/day × 5-10 days) by gavage to female Hsd:Sprague DawleySD (SD) rats. Cumulative excretion via feces increased (39-60%) with dose (0.1-10 µmol/kg) with corresponding decreases in urinary excretion (54 to 37%) after 72?h. Delayed excretion of [14C]-radioactivity in urine and feces of a 100 µmol/kg oral dose was noted. Recovery was complete for all doses by 72?h. IV-injected rats excreted more of the 0.1 µmol/kg dose in urine and less in feces than did gavaged rats, indicating partial biliary elimination of systemically available compound. No tissue bioaccumulation was found for rats given 5 oral daily doses of EH-TBB. Parent molecule was not detected in urine whereas 2 metabolites, tetrabromobenzoic acid (TBBA), a TBBA-sulfate conjugate, and a TBBA-glycine conjugate were identified. EH-TBB and TBBA were identified in extracts from feces. Data from gavaged male B6C3F1/Tac mice indicated minimal sex- or species differences are likely for the disposition of EH-TBB. Approximately 85% of a 0.1 µmol/kg dose was absorbed from the gut. Overall absorption of EH-TBB is expected to be even greater at lower levels.
Project description:The first withdrawal of certain polybrominated diphenyl ethers flame retardants from the US market occurred in 2004. Since then, use of brominated non-PBDE compounds such as bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (BEH-TEBP) and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) in commercial formulations has increased. Assessing human exposure to these chemicals requires identifying metabolites that can potentially serve as their biomarkers of exposure. We administered by gavage a dose of 500 mg/Kg bw of Uniplex FRP-45 (>95 % BEH-TEBP) to nine adult female Sprague-Dawley rats. Using authentic standards and mass spectrometry, we positively identified and quantified 2,3,4,5-tetrabromo benzoic acid (TBBA) and 2,3,4,5-tetrabromo phthalic acid (TBPA) in 24-h urine samples collected 1 day after dosing the rats and in serum at necropsy, 2 days post-exposure. Interestingly, TBBA and TBPA concentrations correlated well (R (2) = 0.92). The levels of TBBA, a known metabolite of EH-TBB, were much higher than the levels of TBPA both in urine and serum. Because Uniplex FRP-45 was technical grade and EH-TBB was present in the formulation, TBBA likely resulted from the metabolism of EH-TBB. Taken together, our data suggest that TBBA and TBPA may serve as biomarkers of exposure to non-PBDE brominated flame retardant mixtures. Additional research can provide useful information to better understand the composition and in vivo toxicokinetics of these commercial mixtures.
Project description:BACKGROUND:Firemaster® 550 (FM550) is commonly added to residential furniture to reduce its flammability. Recent toxicological evidence suggests that FM550 may be endocrine disrupting and obesogenic. OBJECTIVES:Our objectives were to develop methods to assess exposure to FM550 in human populations and to identify potential routes of exposure. METHODS:Using mass spectrometry methods, we developed a method to measure 2,3,4,5-tetrabromobenzoic acid (TBBA), a urinary metabolite of the major brominated FM550 component 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB). The method was applied to a cohort of adult volunteers (n = 64). Participants completed questionnaires, provided urine and handwipe samples, and collected dust samples from their homes. We measured TBB and the other major brominated FM550 component, bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (TBPH), in paired dust and handwipe samples. RESULTS:TBBA was detected in 72.4% of urine samples. Although TBBA is a rapidly formed metabolite, analyses indicated moderate temporal reliability (interclass correlation coefficient = 0.56; 95% confidence interval: 0.46, 0.66). TBB and TBPH were detected frequently in dust samples [geometric mean (GM) = 315.1 and 364.7 ng/g, respectively] and in handwipes (GM = 31.4 and 23.4 ng, respectively). Levels of TBB and TBPH in dust were positively correlated with levels in handwipes. In addition, levels of TBB in handwipes were positively correlated with urinary TBBA. Results suggest frequent hand washing may reduce the mass of TBB on participants' hands and reduce urinary TBBA levels. CONCLUSIONS:Cumulatively, our data indicate that exposures to FM550 are widespread and that the home environment may be an important source of exposure. Urinary TBBA provides a potentially useful biomarker of FM550 exposure for epidemiologic studies.
Project description:Background:Zinc deficiency can change the concentrations of minerals and trace elements in the body. However, previous studies still had many limitations. Objective:To reveal the effects of zinc deficiency on homeostasis of 16 minerals and trace elements. Methods:Forty-five rats were divided randomly into three groups: normal zinc diet (30?mg/kg), low zinc diet (10?mg/kg), and pair-fed diet(30?mg/kg). The concentrations of 16 minerals and trace elements in serum, feces, urine, and liver were measured by inductively coupled plasma mass spectrometry. The excretion of 16 elements in urine and feces were calculated and compared. Results:Zinc-deficient rats exhibited significant changes in up to 12 minerals and trace elements. The low zinc diet induced decreased excretion of zinc and concentrations of zinc in serum, feces, urine, and liver. Zinc deficiency increased feces concentrations of Mg, Cu, Se, K, Ag, Fe and Mn; decreased the concentrations of Mg, Cu, Se, K in liver and urine, and a diminished amount of Ag was observed in serum. Decreased urinary concentrations of Zn Ca, Mg, Cu, Se, K, Na, As and Cr, suggested that zinc-deficient rats increased the 9 elements' renal reabsorption. Decreased concentrations of Ca in liver, urine, and feces, decreased excretion in urine and feces and increased serum total Ca suggested that zinc deficiency increased the redistribution of Ca in serum or other tissues. Zinc deficiency increased excretion of Cu, Se, Fe; and decreased the excretion of other 8 elements except for Ag. Conclusions:Zinc deficiency changed the excretion, reabsorption and redistribution of 12 minerals and trace elements in rats. Our findings are the first to show that zinc deficiency alters the concentrations of Ag, Cr, and As. Graphical abstract: Supplementary information:Supplementary information accompanies this paper at 10.1186/s12986-019-0395-y.
Project description:N-Butylbenzenesulfonamide (NBBS) is a plasticizer detected in the environment suggesting potential human exposure. These studies investigated the in vitro hepatic clearance and disposition of [14C]NBBS in rodents following a single gavage (2, 20 or 200?mg/kg) or intravenous (IV) administration (20?mg/kg). NBBS was cleared slower in hepatocytes from humans compared to rodents. [14C]NBBS was well-absorbed in male rats following gavage administration and excreted extensively in urine (70-76 %) and feces (11-15 %) 72?h following administration. Following a 20?mg/kg gavage dose in male rats, 25 % of the dose was excreted in bile by 24?h suggesting that observed fecal excretion was due to biliary excretion. The radioactivity was distributed to tissues with 14 % and 8 % of the administered dose remaining in tissues at 24 and 72?h, respectively. There was no apparent dose-dependent effect in disposition in male rats. Disposition patterns were similar in female rats (urine, 83 %; feces, 14 %) and male (urine, 69 %; feces, 11 %) and female (urine, 72 %; feces, 9 %) mice following gavage administration of 20?mg/kg. The disposition following IV administration was similar to that of gavage. Urinary radiochemical profiles were similar between doses, routes, species, and sexes. Among numerous metabolites identified, oxidative metabolites of NBBS predominated.
Project description:Triclocarban is a residue-producing antibacterial agent used in a variety of consumer products. These studies investigated the disposition and metabolism of [<sup>14</sup>C]triclocarban. In male rats following a single gavage administration of 50, 150, and 500?mg/kg, excretion was primarily via feces (feces, 85-86%; urine, 3-6%) with no apparent dose-related effect. In male rats, 29% of the administered dose was excreted in bile suggesting some of the fecal excretion is from the absorbed dose which was excreted to the intestine via bile. The tissue retention of radioactivity was low in male rats (24?h, 3.9%; 72?h, 0.1%). Disposition pattern following gavage administration of 50?mg/kg in female rats and male and female mice were similar to male rats. Plasma elimination half-life of triclocarban in rats following gavage administration was shorter (?2?h) compared to that based on total radioactivity (?9?h) which included all products of triclocarban. Absorption following a single dermal application of 1.5 or 3% was low (?3%) in rodents. Hydroxylated and conjugated metabolites of triclocarban predominated in bile. In hepatocytes, clearance of triclocarban in mouse and human was similar and was faster than in rat.
Project description:The use of alternative chemical flame retardants in consumer products is increasing as the result of the phase-out of polybrominated diphenyl ethers. Today, the most commonly detected alternatives in residential furniture include the organophosphate flame retardants (PFRs) and the Firemaster (R) 550 mixture (FM550). Urinary levels of dialkyl and diaryl phosphate esters, and 2-ethylhexyl tetrabromobenzoate (EH-TBB) have been used as biomarkers of human exposure to PFRs and FM550, respectively. In a previous study, we demonstrated that toddlers had significantly higher levels of PFRs relative to their mothers in a cohort from New Jersey; however, it is unclear if there are regional differences in exposure. It is possible that exposure to PFRs may be higher in California relative to other US States due to the California flammability standard, as was seen previously observed for PBDEs. In the current study, we examined urinary levels of PFR metabolites and TBBA in 28 mother-child pairs from California, USA, collected in 2015, and compared them with levels measured in our previous study from New Jersey. Urine samples were extracted using solid-phase extraction and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Diphenyl phosphate (DPHP), isopropyl-phenyl phenyl phosphate (ip-PPP), bis(1,3-dichloro-2propyl) phosphate (BDCIPP) and BCIPHIPP conjugates were detected in 100% of mother and child urine samples, while bis(1-chloro-2-propyl) phosphate (BCIPP), tert-butyl-phenyl phenyl phosphate (tb-PPP) and TBBA were detected in < 50% of samples. Interestingly, BCIPHIPP conjugates were detected in 100% of the urine samples, suggesting ubiquitous exposure to the parent compound, tris(1-chloro-2-propyl) phosphate (TCIPP). The current study found significantly higher BDCIPP levels in California toddlers and higher and ip-PPP levels in mothers as compared to the New Jersey cohort, which may be reflective of California's furniture flammability standard. For example, BDCIPP levels in California children were 2.4 times higher than those in New Jersey children. Consistent with our previous work, the current study showed higher PFR and EH-TBB exposure in children, likely due to increased hand-mouth behavior. Children's DPHP and BDCIPP levels, on average, were 5.9 times and 15 times those of their mothers. Positive correlations between paired mothers and their children were shown for DPHP and BCIPHIPP conjugates but not BDCIPP or ip-PPP. In the children, several predictors of hand-mouth behavior were associated with BDCIPP, DPHP and ip-PPP urine levels, but no associations were observed with BCIPHIPP conjugates.
Project description:2,4,6-tribromophenol (TBP, CAS No. 118-79-6) is widely used as a brominated flame retardant and wood antifungal agent. TBP is frequently detected in environmental matrices, biota, and humans. In female SD rats, systemically available TBP (10?µmol/kg, IV) was rapidly excreted primarily via urine, with approximately 61% of the dose recovered after 4?h, and 89%-94% in 24 h; 5% was recovered in feces; and 1%-2% in blood/tissues. TBP administered to female SD rats (0.1-1000?µmol/kg) by gavage was well absorbed, with approximately 25% eliminated via urine after 4?h and approximately 88% after 24?h. Approximately 11% of a single oral dose was recovered in bile. Male SD rats and B6C3F1/J mice of both sexes had similar disposition profiles when administered a single oral dose of TBP (10?µmol/kg). Following administration, fecal recoveries varied only slightly by dose, sex, or species. TBP readily passed unchanged through both human (ex vivo only) and rat skin with between 55% and 85% of a 100?nmol/cm2 passing into or through skin. Concentrations of TBP in blood fit a two-compartment model after IV-dosing and a one-compartment model after oral dosing. Urine contained a mixture of TBP, TBP-glucuronide, and TBP-sulfate. Fecal extracts contained only parent TBP whereas bile contained only TBP-glucuronide. TBP did not appear to bioaccumulate or alter its own metabolism after repeated administration. TBP was readily absorbed at all doses and routes tested with an oral bioavailability of 23%-27%; 49% of TBP is expected to be dermally bioavailable in humans. From these data, we conclude that humans are likely to have significant systemic exposure when TBP is ingested or dermal exposure occurs.
Project description:To investigate the routes of elimination and excretion for triptolide recovered in rats.After a single oral administration of [(3)H]triptolide (0.8 mg/kg, 100 μCi/kg) in Sprague Dawley rats, urine and fecal samples were collected for 168 h. To study biliary excretion, bile samples were collected for 24 h through bile duct cannulation. Radioactivity was measured using a liquid scintillation analyzer, and excretion pathway analysis was performed using an HPLC/on-line radioactivity detector.The total radioactivity recovered from the urine and feces of rats without bile duct ligation ranged from 86.6%-89.1%. Most of the radioactivity (68.6%-72.0%) was recovered in the feces within 72 h after oral administration, while the radioactivity recovered in the urine and bile was 17.1%-18.0% and 39.0%-39.4%, respectively. The HPLC/on-line radiochromatographic analysis revealed that most of the drug-related radioactivity was in the form of metabolites. In addition, significant gender differences in the quantity of these metabolites were found: monohydroxytriptolide sulfates were the major metabolites detected in the urine, feces, and bile of female rats, while only traces of these metabolites were found in male rats.Radiolabeled triptolide is mainly secreted in bile and eliminated in feces. The absorbed radioactivity is primarily eliminated in the form of metabolites, and significant gender differences are observed in the quantity of recovered metabolites, which are likely caused by the gender-specific expression of sulfotransferases.
Project description:2-Ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) and bis(2-ethylhexyl)tetrabromophthalate (BEH-TEBP) are novel brominated flame retardants used in consumer products. A parallelogram approach was used to predict human dermal absorption and flux for EH-TBB and BEH-TEBP. [14C]-EH-TBB or [14C]-BEH-TEBP was applied to human or rat skin at 100nmol/cm2 using a flow-through system. Intact rats received analogous dermal doses. Treated skin was washed and tape-stripped to remove "unabsorbed" [14C]-radioactivity after continuous exposure (24h). "Absorbed" was quantified using dermally retained [14C]-radioactivity; "penetrated" was calculated based on [14C]-radioactivity in media (in vitro) or excreta+tissues (in vivo). Human skin absorbed EH-TBB (24±1%) while 0.2±0.1% penetrated skin. Rat skin absorbed more (51±10%) and was more permeable (2±0.5%) to EH-TBB in vitro; maximal EH-TBB flux was 11±7 and 102±24pmol-eq/cm2/h for human and rat skin, respectively. In vivo, 27±5% was absorbed and 13% reached systemic circulation after 24h (maximum flux was 464±65pmol-eq/cm2/h). BEH-TEBP in vitro penetrance was minimal (<0.01%) for rat or human skin. BEH-TEBP absorption was 12±11% for human skin and 41±3% for rat skin. In vivo, total absorption was 27±9%; 1.2% reached systemic circulation. In vitro maximal BEH-TEBP flux was 0.3±0.2 and 1±0.3pmol-eq/cm2/h for human and rat skin; in vivo maximum flux for rat skin was 16±7pmol-eq/cm2/h. EH-TBB was metabolized in rat and human skin to tetrabromobenzoic acid. BEH-TEBP-derived [14C]-radioactivity in the perfusion media could not be characterized. <1% of the dose of EH-TBB and BEH-TEHP is estimated to reach the systemic circulation following human dermal exposure under the conditions tested. CHEMICAL COMPOUNDS STUDIED IN THIS ARTICLE:2-Ethylhexyl 2,3,4,5-tetrabromobenzoate (PubChem CID: 71316600; CAS No. 183658-27-7 FW: 549.92g/mol logPest: 7.73-8.75 (12)) Abdallah et al., 2015a. Other published abbreviations for 2-ethylhexyl-2,3,4,5-tetrabromobenzoate are TBB EHTeBB or EHTBB Abdallah and Harrad, 2011. bis(2-ethylhexyl) tetrabromophthalate (PubChem CID: 117291; CAS No. 26040-51-7 FW: 706.14g/mol logPest: 9.48-11.95 (12)). Other published abbreviations for bis(2-ethylhexyl)tetrabromophthalate are TeBrDEPH TBPH or BEHTBP.
Project description:The aim of this study is to examine the effects of acute administration of luseogliflozin, the sodium-glucose cotransporter 2 (SGLT2) inhibitor, on renal hemodynamics and tubular functions in anesthetized non-diabetic Sprague Dawley (SD) rats and 5/6 nephrectomized (Nx) SD rats. Renal blood flow (RBF), mean arterial pressure (MAP), and heart rate (HR) were continuously measured and urine was collected directly from the left ureter. Intraperitoneal injection of luseogliflozin (0.9?mg?kg<sup>-1</sup>) did not change MAP, HR, RBF, or creatinine clearance (CrCl) in SD rats (n?=?7). Luseogliflozin significantly increased urine volume, which was associated with significantly increased urinary glucose excretion rates (P?<?0.001). Similarly, luseogliflozin significantly increased urinary sodium excretion (from 0.07?±?0.01?µmol min<sup>-1</sup> at baseline to 0.76?±?0.08?µmol min<sup>-1</sup> at 120?min; P?<?0.001). Furthermore, luseogliflozin resulted in significantly increased urinary pH (P?<?0.001) and decreased urinary osmolality and urea concentration (P?<?0.001) in SD rats. Similarly, in Nx SD rats (n?=?5-6), luseogliflozin significantly increased urine volume and urinary glucose excretion (P?<?0.001) without altering MAP, HR, RBF, or CrCl. Luseogliflozin did not elicit any significant effects on the other urinary parameters in Nx SD rats. These data indicate that SGLT2 inhibitor elicits direct tubular effects in non-diabetic rats with normal renal functions.