Diphenyl Ether Mixture Research Articles

Associations of cord serum polybrominated diphenyl ether (PBDE) mixture with birth outcomes and mediating role of thyroid function: Evidence from the Sheyang Mini Birth Cohort Study

BackgroundPolybrominated diphenyl ethers (PBDEs), a series of worldwide applied flame retardants, may influence fetal growth and interfere with thyroid function. The study intended to explore the relationship between in-utero exposure to PBDE mixture and newborn anthropometric indexes and to further examine the potential mediating role of thyroid function. MethodsDemographics and laboratory measures of 924 mother-infant pairs were obtained from the database of the Sheyang Mini Birth Cohort Study. We applied gas chromatography-mass spectrometry (GC-MS) and electrochemiluminescence immunoassay to measure nine PBDE congeners and seven thyroid function parameters in umbilical cord serum samples, respectively. We fitted generalized linear models and Bayesian kernel machine regression (BKMR) to evaluate associations of lipid-adjusted cord serum PBDEs, as individuals and as a mixture, with newborn anthropometric and cord serum thyroid function parameters. We applied causal mediation analysis to test our hypothesis that thyroid function parameters act as a mediator between PBDEs and birth outcomes. ResultsThe molarity of cord serum ∑9PBDE had a median value of 31.23 nmol/g lipid (IQR 19.14 nmol/g lipid, 54.77 nmol/g lipid). BDE-209 was the most dominant congener. Birth length was positively associated with both single exposure to BDE-28 and cumulative exposure to PBDEs. Correspondingly, ponderal index (PI) was negatively associated with BDE-28 and the total effects of PBDE mixture. Free triiodothyronine had a negative trend with BDE-209 and PBDE mixture. In the sex-stratified analysis, BDE-153 concentrations were positively correlated with PI among males (β = 0.03; 95%CI: 0.01, 0.05; P = 0.01) but not among females. Cord serum thyrotropin mediated 14.92% of the estimated effect of BDE-153 on PI. ConclusionsIn-utero mixture exposure to PBDEs was associated with birth outcomes and thyroid function. Thyroid function might act as a mediator in the process in which PBDEs impact the growth of the fetus.

Flash point and safety evaluation of binary mixture of diphenyl ether + biphenyl: A commonly utilized heat transfer fluid

The binary mixture of diphenyl ether and biphenyl finds wide applications in various industries. Notably, it is widely utilized in renewable energy systems such as concentrated solar power (CSP) facilities. This study addresses the lack of research on the flash point (FP) behavior of this blend, crucial due to high operating temperatures in related processes, especially when used as a heat transfer fluid. This study fills the research gap by analyzing the entire composition range, using experimental measurements, and a unique mathematical method based on SLE data; unlike the conventional method that relies on VLE data. The FP prediction results demonstrated satisfactory outcomes when compared to the experimental data. The findings of this study can be employed to mitigate the fire and explosion risks associated with processes using the binary mixture of diphenyl ether + biphenyl.

Biotransformation of Dec-604 and potential effect on thyroid deiodinase activity in highly flame retardant-exposed gulls

Several halogenated flame retardants (HFRs) have been identified as thyroid disruptors in birds including the polybrominated diphenyl ether (PBDE) mixtures, which have been replaced with other HFRs such as Dechlorane-604 (Dec-604). Dec-604 Component B (Dec-604 CB), a putative debrominated product of Dec-604, has been frequently reported in urban-adapted ring-billed gulls (Larus delawarensis) breeding in the Montreal area (QC, Canada). The metabolic pathways of Dec-604 are yet to be characterized, although the occurrence of Dec-604 CB in gulls may suggest that enzyme-mediated dehalogenation may occur, potentially involving the thyroid deiodinases. The objective of this study was to investigate the effect of Dec-604 on type 1 deiodinase (DIO1) in the presence of thyroxine (T4) in an in vitro DIO1 assay using liver microsomes of ring-billed gulls that are highly exposed to HFRs in the Montreal area, and to determine whether DIO1 is involved in the in vitro debromination of Dec-604. We tested the in vitro activity of DIO1 in gull liver microsomes in the presence of five concentrations of Dec-604 ranging from 0.86 to 86.21 nM. HFR concentrations (Σ40HFR) were also determined in liver samples of gulls. Results showed that total DIO1 activity in gull liver microsomes was increased by three of the five concentrations of Dec-604. No relationship between liver Σ40HFR concentrations and DIO1 activity was observed, except for T2 formation rates that significantly decreased with increasing liver HFR concentrations. Moreover, greater Dec-604 CB to Dec-604 concentration ratios in activated gull microsomes (with the DIO1 cofactor dithiothreitol) were found at the intermediate Dec-604 concentration compared to controls. These results suggested that liver microsome DIO1 activity may be perturbed in ring-billed gulls exposed to Dec-604, and be involved at least in part, in the debromination of Dec-604 leading to the formation of Dec-604 CB.

Legacy and emerging flame retardants in sharks from the Western North Atlantic Ocean

Following the discontinuation of commercial polybrominated diphenyl ether (PBDE) mixtures, a variety of alternative flame retardants (FRs) have been developed and employed. To understand the contamination status of these emerging FRs in marine fish and wildlife, we investigated their bioaccumulation in four shark species, including shortfin mako shark (Isurus oxyrhinchus; n = 26), porbeagle (Lamna nasus; n = 4), sandbar shark (Carcharhinus plumbeus; n = 6), and common thresher (Alopias vulpinus; n = 4), from coastal and offshore waters of the western North Atlantic Ocean. Median concentrations of emerging FRs, including dechlorane analogues (i.e., dechlorane plus, Dec-602, −603, and − 604), tetrabromo-o-chlorotoluene (TBCT), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), and hexabromobenzene (HBBZ), ranged from 1.4–7.4, 10.2–22.4, 1.0–16.7, and 4.1–17.7 ng/g lipid weight (lw), respectively. Although concentrations of emerging FRs were generally 1–2 orders of magnitude lower than those of legacy FRs (i.e., PBDEs, 312–800 ng/g lw and hexabromocyclododecane or HBCDD, 17.2–99.3 ng/g lw), they were detected in more than 80% of the shark livers. Analysis of available biological data indicated that fork length significantly correlated with the concentrations of ΣPBDEs, HBCDD, ΣDechloranes or TBCT in shortfin mako livers. This indicates that longer-term exposure likely results in elevated FR concentrations in sharks. Our findings suggest likely exposure of western North Atlantic fish and wildlife to several emerging FRs, including dechloranes, BTBPE, HBBZ, and TBCT. Additional studies are needed to better elucidate their potential risks to fish and wildlife as well as the variety of environmental and biological factors influencing these risks.

Densities for Sulfur in Benzene and Densities with Solubilities for a Eutectic Mixture of Biphenyl plus Diphenyl Ether: A General Solubility Equation for the Treatment of Aromatic Physical Sulfur Solvents

Physical sulfur solvents are utilized in (i) the mitigation of sulfur deposition in sour gas wells and gathering lines and (ii) as a process medium for small-scale sulfur recovery. Non-aqueous aromatic solvents have two distinct advantages, where they are less reactive with elemental sulfur and provide for relatively large sulfur solubilities. Understanding the solubilities and physical properties within aromatic sulfur solvents over a wide range of temperature and pressure is important for both the previous applications. In this study, high-pressure densities for sulfur in benzene and a eutectic mixture of biphenyl and diphenyl ether were measured for T = (298.15–373.15) K and p < 100 MPa, where the densities were used to calculate the molar volume change upon dissolution. New sulfur solubility measurements are reported for sulfur in the eutectic mixture of biphenyl and diphenyl from T = (298.15–403.15) K and compared to benzene, toluene, and xylenes (BTX). The calculated volumetric changes and measured solubilities at atmospheric pressure were used to determine the enthalpy of dissolution, ΔX→slH°, and the change in heat capacity, ΔX→slCp°, for the α-sulfur, β-sulfur, and the liquid-sulfur phase dissolution using a van’t Hoff model. The eutectic solvent showed a higher solubility when compared to BTX at higher temperatures (β-sulfur and the liquid-sulfur regions) and both solubilities calculated to have a very small pressure dependence.

Developmental exposure to the DE-71 mixture of polybrominated diphenyl ether (PBDE) flame retardants induce a complex pattern of endocrine disrupting effects in rats.

Polybrominated diphenyl ethers (PBDEs) are legacy compounds with continued widespread human exposure. Despite this, developmental toxicity studies of DE-71, a mixture of PBDEs, are scarce and its potential for endocrine disrupting effects in vivo is not well covered. To address this knowledge gap, we carried out a developmental exposure study with DE-71. Pregnant Wistar rat dams were exposed to 0, 40 or 60 mg/kg bodyweight/day from gestation day 7 to postnatal day 16, and both sexes were examined. Developmental exposure affected a range of reproductive toxicity endpoints. Effects were seen for both male and female anogenital distances (AGD), with exposed offspring of either sex displaying around 10% shorter AGD compared to controls. Both absolute and relative prostate weights were markedly reduced in exposed male offspring, with about 40% relative to controls. DE-71 reduced mammary gland outgrowth, especially in male offspring. These developmental in vivo effects suggest a complex effect pattern involving anti-androgenic, anti-estrogenic and maybe estrogenic mechanisms depending on tissues and developmental stages. Irrespective of the specific underlying mechanisms, these in vivo results corroborate that DE-71 causes endocrine disrupting effects and raises concern for the effects of PBDE-exposure on human reproductive health, including any potential long-term consequences of disrupted mammary gland development.

Contamination status, emission sources, and human health risk of brominated flame retardants in urban indoor dust from Hanoi, Vietnam: the replacement of legacy polybrominated diphenyl ether mixtures by alternative formulations.

This study investigated the occurrence, distribution of several additive brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and some novel brominated flame retardants (NBFRs) in urban indoor dust collected from ten inner districts of Hanoi, Vietnam to assess the contamination status, emission sources, as well as their associated human exposure through indoor dust ingestion and health risks. Total concentrations of PBDEs and NBFRs in indoor dust samples ranged from 43 to 480 ng g-1 (median 170 ng g-1) and from 56 to 2200 ng g-1 (median 180 ng g-1), respectively. The most abundant PBDE congener in these dust samples was BDE-209 with concentrations ranging from 29 to 360 ng g-1, accounting for 62.6-86.5% of total PBDE levels. Among the NBFRs analyzed, decabromodiphenyl ethane (DBDPE) was the predominant compound with a mean contribution of 98.6% total NBFR amounts. Significant concentrations of DBDPE were detected in all dust samples (median 180 ng g-1, range 54-2200 ng g-1), due to DBDPE as a substitute for deca-BDE. Other NBFRs such as 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), pentabromoethylbenzene (PBEB) and 2,2',4,4',5,5'-hexabromobiphenyl (BB-153) were found at very low levels. Based on the measured BFR concentrations, daily intake doses (IDs) of PBDEs and NBFRs via dust ingestion at exposure scenarios using the median and 95th percentile levels for both adults and children were calculated for risk assessment. The results showed that the daily exposure doses via dust ingestion of all compounds, even in the high-exposure scenarios were also lower than their reference dose (RfD) values. The lifetime cancer risks (LTCR) were much lower than the threshold level (10-6), which indicated the acceptable health risks resulting from indoor BFRs exposure for urban residents in Hanoi.

Synthesis and properties of novel poly(ether ketone ketone)s containing 1,4‐naphthylene units by electrophilic solution copolycondensation

AbstractSemicrystalline poly(aryl ether ketone)s (PAEKs) represent an industrially important class of high‐performance engineering thermoplastics with excellent physicochemical and mechanical properties, and the synthesis of PAEKs with enhanced glass transition temperatures (Tg) and moderate melting temperatures (Tm) is highly desirable. In the work reported, novel poly(ether ketone ketone)s (PEKKs) containing 1,4‐naphthylene units in main chains were synthesized by Friedel–Crafts solution copolycondensation of terephthaloyl chloride with a mixture of diphenyl ether and 1,4‐di(4‐phenoxybenzoyl)naphthalene (1,4‐DPOBN). The polymerization proceeded smoothly in 1,2‐dichloroethane in the presence of anhydrous AlCl3andN‐methylpyrrolidone under mild conditions and afforded polymers having inherent viscosities of 0.66–0.98 dL g−1. The polymers with 5–30 mol% 1,4‐DPOBN are semicrystalline and have obviously enhancedTgover commercial poly(ether ether ketone)s and PEKKs due to the incorporation of rigid and bulky 1,4‐naphthylene moieties into the main chain. The polymers with 20–30 mol% 1,4‐DPOBN not only have highTgof 175–177 °C, but also relatively lowTmof 331–336 °C, having high potential for melt processing. The polymers with 20–30 mol% 1,4‐DPOBN also exhibit excellent thermal stability and good mechanical and solvent‐resistance properties. © 2021 Society of Chemical Industry

A study on hydrogen uptake and release of a eutectic mixture of biphenyl and diphenyl ether

Abstract Hydrogen storage in Liquid Organic Hydrogen Carrier (LOHC) systems is appealing for the safe storage and distribution of excess renewable energy via existing gasoline infrastructures to end-users. We present the eutectic mixture of biphenyl and diphenyl ether of its first use as a LOHC material. The material is hydrogenated with 99% selectivity without the cleavage of C O bond, with commercial heterogeneous catalysts, which is confirmed by nuclear magnetic spectroscopy and gas chromatography-mass spectrometry. Equilibrium concentration, dehydrogenation enthalpy, and thermo-neutral temperature are calculated using a density functional theory. The results indicate that O-atom-containing material exhibits more favorable dehydrogenation thermodynamics than that of the hydrocarbon analogue. The H2-rich material contains 6.8 wt% of gravimetric hydrogen storage capacity. A preliminary study of catalytic dehydrogenation on a continuous reactor is presented to demonstrate a reversibility of this material.

Unusually high Deca-BDE concentrations and new flame retardants in a Canadian Arctic top predator, the glaucous gull

Despite a sustained effort in surveying flame retardants (FRs) in wildlife from industrialized regions, their occurrence in birds or any other wildlife species spanning the Arctic regions, particularly in North America, has received limited attention. This study investigated in the top predator glaucous gull (Larus hyperboreus) breeding in the Eastern Canadian Arctic (Cape Dorset, Nunavut) a comprehensive suite of FRs including unstudied halogenated and non-halogenated FRs of potential health concern, along with legacy organochlorines and mercury. The influence of diet acquired locally and in wintering areas on the tissue contaminant profiles was also investigated using δ15N and δ13C signatures in liver and feathers. The principal constituent in the Deca-brominated diphenyl ether (BDE) mixture, BDE-209, was remarkably the most concentrated PBDE congener determined in liver samples of Eastern Canadian Arctic glaucous gulls. This suggests dietary exposure from the local marine food web and perhaps also from nearby community landfills. Moreover, this study revealed for the first time the presence of 16 emerging halogenated and non-halogenated FRs in glaucous gulls from this Arctic region including HBB, DDC-CO (anti and syn isomers), PBEB, EHTBB, BEHTBP as well as a series of organophosphate esters (OPEs) (TCEP, TCIPP, TPP, TDCIPP, TDBPP, TBNP, TBOEP, TBEP, TCrP, EHDPP, and TEHP). With the exception of BDE-209, concentrations of other halogenated FRs and organochlorines were found to be in the lower range in liver of Eastern Canadian Arctic glaucous gulls compared to individuals from other circumpolar populations (Svalbard and Greenland). Mercury and methylmercury concentrations, however, were greater than reported elsewhere for glaucous gull populations.

Interaction between deca-BDE and hepatic deiodinase in a highly PBDE-exposed bird

Studies have shown that debromination of the major component in the deca-brominated diphenyl ether mixture (deca-BDE), BDE-209, occurs in vivo in birds. Recent work from our laboratory on breeding ring-billed gulls (Larus delawarensis) exposed to elevated PBDE concentrations in the densely-populated metropolis of Montreal (Canada) further suggests that BDE-209 debromination is potentially catalyzed by deiodinases in liver microsomes. The first objective of this study was to determine if type 1 deiodinase (D1) was involved in the in vitro debromination of BDE-209 in liver microsomes of ring-billed gulls. The second objective was to determine if there was an interaction between D1 and BDE-209 using an in vitro D1 activity assay. No depletion of BDE-209 was observed in gull liver microsomes. A significant 42% increase in total D1 activity was found in gull liver microsomes at the medium BDE-209 concentration (1.0 nM), although not at the low (0.5 nM) or high (2.5 nM) concentrations, suggesting potential non-dose related interaction with D1. Moreover, no correlation was found between total D1 activity in liver microsomes and plasma thyroid hormone levels, although there was a negative relationship between plasma BDE-209 concentrations and FT3 levels. Results from this study suggest that debromination of BDE-209 did not occur using present in vitro assay conditions, although indicated potential interaction with D1 that may have implication on circulating thyroid hormone status.

Carcinogenic activity of pentabrominated diphenyl ether mixture (DE-71) in rats and mice.

Pentabrominated diphenyl ether (PBDE) flame retardants have been phased out in Europe and in the United States, but these lipid soluble chemicals persist in the environment and are found human and animal tissues. PBDEs have limited genotoxic activity. However, in a 2-year cancer study of a PBDE mixture (DE-71) (0, 3, 15, or 50 mg/kg (rats); 0, 3, 30, or 100 mg/kg (mice)) there were treatment-related liver tumors in male and female Wistar Han rats [Crl:WI(Han) after in utero/postnatal/adult exposure, and in male and female B6C3F1 mice, after adult exposure. In addition, there was evidence for a treatment-related carcinogenic effect in the thyroid and pituitary gland tumor in male rats, and in the uterus (stromal polyps/stromal sarcomas) in female rats. The treatment-related liver tumors in female rats were unrelated to the AhR genotype status, and occurred in animals with wild, mutant, or heterozygous Ah receptor. The liver tumors in rats and mice had treatment-related Hras and Ctnnb mutations, respectively. The PBDE carcinogenic activity could be related to oxidative damage, disruption of hormone homeostasis, and molecular and epigenetic changes in target tissue. Further work is needed to compare the PBDE toxic effects in rodents and humans.

Photolysis and chromatographic analysis of biphenyl and diphenyl ether mixtures in soil by infrared lamp irradiation

To study the environmental behaviors of soil-bound pollutants, it is meaningful to investigate the photolysis of organic pollutants in soil. The pure biphenyl and diphenyl ether mixtures, one of synthetic heat transfer oil, which are the most widely used thermal fluid in solar centrals, were used in this experiment. The photolysis of the mixtures in soil with infrared lamp irradiation were analyzed experimentally using the gas chromatograph. The ultrasonic cleaner was utilized to make the adsorbent gas in the activated charcoal tube dissolved well with analytic agent. The retention time, peak area and peak height was measured by the hydrogen flame ionization detector (FID) technique. The biphenyl and diphenyl ether mixtures can indeed be decomposed by infrared light, although the amount of decomposition was rather small. The results demonstrated that the new substances were various both at different infrared lamp lighting periods and outlets. The proportion between biphenyl and diphenyl ether, of which the mass ratio was no longer 26.5: 73.5, was diverse at different infrared lighting periods and outlets, and the attribution of diphenyl ether to the loss was always higher than that of biphenyl from the analysis of peak area. Based on the chromatographic analysis of condensed liquid mixtures, the decomposition of biphenyl and diphenyl ether mixtures was not only restricted to the time periods of exposure to infrared lamp. The results suggested a reference to prevent soil and groundwater contamination and soil remediation.

Anthropogenic and Naturally Produced Brominated Phenols in Pet Blood and Pet Food in Japan.

Present study determined concentrations and residue patterns of bromophenols (BPhs) in whole blood samples of pet cats and pet dogs collected from veterinary hospitals in Japan. BPhs concentrations were higher in cat blood than in dog blood, with statistically insignificant differences (p = 0.07). Among the congeners, 2,4,6-tribromophenol (TBPh) constituted the majority of BPhs (>90%) detected in both species. Analysis of commercial pet food to estimate exposure routes showed that the most abundant congener in all pet food samples was 2,4,6-TBPh, accounting for >99% of total BPhs. This profile is quite similar to the blood samples of the pets, suggesting that diet might be an important exposure route for BPhs in pets. After incubation in polybrominated diphenyl ether (PBDE) mixtures (BDE-47, BDE-99 and BDE-209), 2,4,5-TBPh was found in dog liver microsomes but not in cat liver microsomes, implying species-specific metabolic capacities for PBDEs. Formation of 2,4,5-TBPh occurred by hydroxylation at the 1' carbon atom of the ether bond of BDE-99 is similar to human study reported previously. Hydroxylated PBDEs were not detected in cats or dogs; therefore, diphenyl ether bond cleavage of PBDEs can also be an important metabolic pathway for BPhs formation in cats and dogs.

Synthesis and properties of novel copolymers of poly(ether ketone ketone) and poly(ether sulfone ether ketone ketone) containing 1,4-naphthylene moieties

A new monomer containing naphthalene and sulfone groups, 4,4′-bis(1-naphthoxy)diphenylsulfone (BNODPS), was easily prepared by the condensation reaction of 4,4′-dichlorodiphenylsulfone with 1-naphthol in the presence of base in dimethyl sulfoxide. Novel copolymers of poly(ether ketone ketone) and poly(ether sulfone ether ketone ketone) containing 1,4-naphthylene moieties were synthesized by the electrophilic Friedel–Crafts acylation copolycondensation of terephthaloyl chloride with a mixture of diphenyl ether (DPE) and BNODPS, over a wide range of DPE/BNODPS molar ratios, in the presence of anhydrous AlCl3 and N-methylpyrrolidone (NMP) in 1,2-dichloroethane. The polymers obtained were characterized by different physicochemical techniques. The copolymers with 5–25 mol% BNODPS are semicrystalline and had remarkably increased Tgs and decreased Tms over the wholly para-linked poly(ether ketone ketone) due to the incorporation of bulky and rigid 1,4-naphthylene moieties and flexible sulfone linkages in the main chains. The copolymer VI with 25 mol% BNODPS had not only high Tg of 185°C but also moderate Tm of 335°C, having good potential for melt processing. The copolymer VI had tensile strength of 102.2 MPa, Young’s modulus of 2.78 GPa, and elongation at break of 15.9% and exhibited high thermal stability and good resistance to organic solvents.

Synergistic solubilization of low-brominated diphenyl ether mixtures in nonionic surfactant micelles

The present study investigated the co-solubilization of three representative low-brominated diphenyl ethers (low-BDEs) in nonionic surfactant micelles. Co-solubilization effects were quantified in terms of molar solubilization ratio (MSR), micelle–water partition coefficient (log Km), extent of synergism/inhibition (RΔMSR), first stepwise association constant (K1), the average number of solute molecules per micelle (SM), excess Gibbs energy (ΔG0 excess), and interaction parameter (ω/RT). The solubilities of low-BDEs during co-solubilization were increased (i.e., synergism) in all of the surfactants tested, relative to their respective solubilities during solubilization. In each surfactant system, synergism was weaker for BDE-15/BDE-28 than that for BDE-15/BDE-47 because BDE-15 and BDE-28 may be partitioned more uniformly in the micelle core than BDE-47, which increased the possibility of their competition. Unexpectedly, BDE-28 and BDE-47 with similar log Kow values demonstrated enhanced co-solubility. This phenomenon was attributed to the positive electrostatic potentials of bromines (computed by Gaussian program) on BDE-28 and BDE-47 which may provide additional attractions to oxygen atoms of the hydrophilic chains. The synergism observed for BDE-15/BDE-28 and BDE-15/BDE-47 was stronger in the Brij35 system than that in Brij58 and Brij78 systems, suggesting that a surfactant with lower aggregation number and/or longer hydrophilic chain length can avoid the competition between solutes for the micelle core. This study may improve the understanding of multi-solutes interactions in surfactant micelles.

Behavioral and thyroid effects of in utero and lactational exposure of Sprague–Dawley rats to the polybrominated diphenyl ether mixture DE71

Exposure of rodents during gestation and lactation to polybrominated diphenyl ethers (PBDEs) has been reported to disrupt neurobehavioral function in offspring, as well as to disrupt thyroid function. To assess this we evaluated development and behavior after gestational and lactational exposure to the technical PBDE mixture DE71. Pregnant Sprague–Dawley rats were exposed to 0, 0.3, 3.0 or 30mg/kg/day of DE71 from gestation day 1 to postnatal day (PND) 21 and were assessed on a wide range of behavioral functions from early postnatal period until old age (PND 450). DE71 exposure decreased thyroid hormone levels (T3 and T4) in mothers and offspring with offspring being more sensitive that mothers. Developmental landmarks, neuromotor function, anxiety, learning and memory were not affected by DE71 at any age. DE71 produced small changes in motor activity rearing only at PND 110 but not at any other age and no other activity measure was altered by DE71. Cholinergic sensitivity measured by nicotine-stimulated motor activity was not affected by perinatal DE71 exposure. Acoustic startle responses were potentiated by DE71 at PND 90 indicating delayed effects on sensory reactivity. Habituation was measured in motor activity tests at five ages but was not altered by DE71 at any age. Habituation measured in startle tests was also not affected by exposure to DE71. For thyroid hormone levels at PND 21, the lowest adverse effect level was 3.0mg/kg. Few behavioral effects were observed and the lowest adverse effect level was 30mg/kg. Our results confirm that DE71 produces transient effects on thyroid hormone levels but does not result in learning or motor impairment and does not alter non-associative learning (habituation).

Monitoring indoor exposure to organophosphate flame retardants: hand wipes and house dust.

Background: Organophosphate flame retardants (PFRs) are becoming popular replacements for the phased-out polybrominated diphenyl ether (PBDE) mixtures, and they are now commonly detected in indoor environments. However, little is known about human exposure to PFRs because they cannot be easily measured in blood or serum.Objectives: To investigate relationships between the home environment and internal exposure, we assessed associations between two PFRs, tris(1,3-dichloropropyl) phosphate (TDCIPP) and triphenyl phosphate (TPHP), in paired hand wipe and dust samples and concentrations of their metabolites in urine samples (n = 53). We also assessed short-term variation in urinary metabolite concentrations (n = 11 participants; n = 49 samples).Methods: Adult volunteers in North Carolina, USA, completed questionnaires and provided urine, hand wipe, and household dust samples. PFRs and PBDEs were measured in hand wipes and dust, and bis(1,3-dichloropropyl) phosphate (BDCIPP) and diphenyl phosphate (DPHP), metabolites of TDCIPP and TPHP, were measured in urine.Results: TDCIPP and TPHP were detected frequently in hand wipes and dust (> 86.8%), with geometric mean concentrations exceeding those of PBDEs. Unlike PBDEs, dust TDCIPP and TPHP levels were not associated with hand wipes. However, hand wipe levels were associated with urinary metabolites. Participants with the highest hand wipe TPHP mass, for instance, had DPHP levels 2.42 times those of participants with the lowest levels (95% CI: 1.23, 4.77). Women had higher levels of DPHP, but not BDCIPP. BDCIPP and DPHP concentrations were moderately to strongly reliable over 5 consecutive days (intraclass correlation coefficients of 0.81 and 0.51, respectively).Conclusions: PFR exposures are widespread, and hand-to-mouth contact or dermal absorption may be important pathways of exposure.Citation: Hoffman K, Garantziotis S, Birnbaum LS, Stapleton HM. 2015. Monitoring indoor exposure to organophosphate flame retardants: hand wipes and house dust. Environ Health Perspect 123:160–165; http://dx.doi.org/10.1289/ehp.1408669

Cadmium and decabrominated diphenyl ether mixture: In vitro evaluation of cytotoxic, prooxidative and genotoxic effects

In order to look into the combined effects of Cd and BDE-209 in vitro, this study was aimed at examining cytotoxic and genotoxic effects using the human colon carcinoma cell line (SW 480) as a biological test system as well as to determine if ROS production was one of the possible mechanisms of their mixture action. This cell line was chosen since ingestion of contaminated food/water represents an important route of exposure to both Cd and BDE-209, which is why intestinal cells are a common target for the contaminants present in food and water. Cells were treated with single Cd in concentrations of 2.5, 7.5 or 15μg Cd/mL (corresponding to 22, 67 or 134μM), single BDE-209 in concentrations of 2.5, 5 or 10μg BDE209/mL (corresponding to 2.5, 5 or 10μM), and their mixtures (design 3×3).Mixture of Cd and BDE-209 has shown clear potential to reduce the viability of SW 480 cells, as evidenced by cytotoxicity associated with ROS generation. Factorial regression models used to identify type of interaction revealed synergism related to mixture citotoxicity and additive interaction for the effect on ROS production. The results from this introductory study could contribute to the issue of possible adverse effects associated with co-exposure and body burden with two persistent environmental pollutants, Cd and BDE-209.

(Solid + liquid) phase equilibria and heat capacity of (diphenyl ether + biphenyl) mixtures used as thermal energy storage materials

The (solid+liquid) phase equilibrium for eight {x diphenyl ether+(1−x) biphenyl} binary mixtures, including the eutectic mixture were studied by using a differential scanning calorimetry (DSC) technique. A good agreement was found between previous literature and experimental values here presented for the melting point and enthalpy of fusion of pure compounds. The well-known equations for Wilson and the non-random two-liquid (NRTL) were used to correlate experimental solid liquid phase equilibrium data. Moreover, the predictive mixture model UNIFAC has been employed to describe the phase diagram. With the aim to check this equipment to measure heat capacities in the quasi-isothermal Temperature-Modulated Differential Scanning Calorimetry method (TMDSC), four fluids of well-known heat capacity such as toluene, n-decane, cyclohexane and water were also studied in the liquid phase at temperatures ranging from (273.15 to 373.15)K. A good agreement with literature values was found for those fluids of pure diphenyl ether and biphenyl. Additionally, the specific isobaric heat capacities of diphenyl ether and biphenyl binary mixtures in the liquid phase up to T=373.15K were measured.