Origin of attraction in p-benzoquinone complexes with benzene and p-hydroquinone.

PubMed

Tsuzuki, Seiji; Uchimaru, Tadafumi; Ono, Taizo

2017-08-30

The origin of the attraction in charge-transfer complexes (a p-hydroquinone-p-benzoquinone complex and benzene complexes with benzoquinone, tetracyanoethylene and Br 2 ) was analyzed using distributed multipole analysis and symmetry-adapted perturbation theory. Both methods show that the dispersion interactions are the primary source of the attraction in these charge-transfer complexes followed by the electrostatic interactions. The natures of the intermolecular interactions in these complexes are close to the π/π interactions of neutral aromatic molecules. The electrostatic interactions play important roles in determining the magnitude of the attraction. The contribution of charge-transfer interactions to the attraction is not large compared with the dispersion interactions in these complexes.

Synthesis and amino acids complexation of tripodal hexasubstituted benzene chiral receptors

NASA Astrophysics Data System (ADS)

Choksakulporn, Saowanaporn; Punkvang, Auradee; Sritana-anant, Yongsak

2015-02-01

The parent 1,3,5-triacetyl-2,4,6-trihydroxybenzene was prepared in up to 91% yield using a one-pot, one step reaction catalyzed by aluminum chloride. Its alkylations with 1,5-dibromopentane generated a symmetric tripodal hexasubstituted benzene precursor in the alternated conformer predicted by a theoretical calculation. Subsequent substitutions and reductions provided the corresponding tris-amine in 59% yield. Aminations of the tripodal precursor with (R)-(+)-1-phenylethylamine obtained a chiral tris-amine ligand in 44% yield. 1H NMR titrations of this ligand with each of three L-amino acid derivatives as guest molecules confirmed the presence of their complexes, in which the complex with alanine derivative displayed the strongest interactions with the ligand. Job plots suggested that all complexes composed of 1:2 ratios of the ligand and these guests. Theoretical calculations additionally revealed the structures and the associated binding parameters of the complexes.

Electron localization in a mixed-valence diniobium benzene complex

DOE PAGES

Gianetti, Thomas L.; Nocton, Grégory; Minasian, Stefan G.; ...

2014-11-11

Reaction of the neutral diniobium benzene complex {[Nb(BDI)N tBu] 2(μ-C 6H 6)} (BDI = N,N'-diisopropylbenzene-β-diketiminate) with Ag[B(C 6F 5) 4] results in a single electron oxidation to produce a cationic diniobium arene complex, {[Nb(BDI)N tBu] 2(μ-C 6H 6)}{B(C 6F 5) 4}. Investigation of the solid state and solution phase structure using single-crystal X-ray diffraction, cyclic voltammetry, magnetic susceptibility, and multinuclear NMR spectroscopy indicates that the oxidation results in an asymmetric molecule with two chemically inequivalent Nb atoms. Further characterization using density functional theory (DFT) calculations, UV-visible, Nb L 3,2-edge X-ray absorption near-edge structure (XANES), and EPR spectroscopies supports assignment ofmore » a diniobium complex, in which one Nb atom carries a single unpaired electron that is not largely delocalized on the second Nb atom. During the oxidative transformation, one electron is removed from the δ-bonding HOMO, which causes a destabilization of the molecule and formation of an asymmetric product. Subsequent reactivity studies indicate that the oxidized product allows access to metal-based chemistry with substrates that did not exhibit reactivity with the starting neutral complex.« less

Enhanced degradation of benzene by percarbonate activated with Fe(II)-glutamate complex.

PubMed

Fu, Xiaori; Gu, Xiaogang; Lu, Shuguang; Miao, Zhouwei; Xu, Minhui; Zhang, Xiang; Danish, Muhammad; Cui, Hang; Farooq, Usman; Qiu, Zhaofu; Sui, Qian

2016-04-01

Effective degradation of benzene was achieved in sodium percarbonate (SPC)/Fe(II)-Glu system. The presence of glutamate (Glu) could enhance the regeneration of Fe(III) to Fe(II), which ensures the benzene degradation efficiency at wider pH range and eliminate the influence of HCO3 (-) in low concentration. Meanwhile, the significant scavenging effects of high HCO3 (-) concentration could also be overcome by increasing the Glu/SPC/Fe(II)/benzene molar ratio. Free radical probe compound tests, free radical scavenger tests, and electron paramagnetic resonance (EPR) analysis were conducted to explore the reaction mechanism for benzene degradation, in which hydroxyl radical (HO•) and superoxide anion radical (O2 (•-)) were confirmed as the predominant species responsible for benzene degradation. In addition, the results obtained in actual groundwater test strongly indicated that SPC/Fe(II)-Glu system is applicable for the remediation of benzene-contaminated groundwater in practice.

The Determination of Molecular Quantities from Measurements on Macroscopic Systems.V. Existence and Properties of 1:1 and 2:1-Electron-Donor-Acceptor Complexes of Hexamethylbenzene with Tetracyanoethylene

NASA Astrophysics Data System (ADS)

Liptay, Wolfgang; Rehm, Torsten; Wehning, Detlev; Schanne, Lothar; Baumann, Wolfram; Lang, Werner

1982-12-01

The formation of electron-donor-acceptor complexes of hexamethylbenzene (HMB) with tetracyanoethylene (TCNE) was investigated by measurements of the optical absorptions, the densities, the permittivities and the electro-optical absorptions of solutions in CCl4. The careful evaluation of data based on some previously reported models, has shown that the assumption of the formation of the 1: 1 and the 2 : 1 complex agrees with all experimental data, but that the assumption of the formation of only the 1: 1 complex is contradictory to experimental facts even if the activity effects on the equilibrium constant and of the solvent dependences of observed molar quantities are taken into account. The evaluation leads to the molar optical absorption coefficients and the molar volumes of both complexes and to their electric dipole moments in the electronic ground state and the considered excited state. According to these results the complexes are of the sandwich type HMB-TCNE and HMB-TCNE-HMB. In spite of the fact that the 2: 1 complex owns a center of symmetry, at least approximately, there is a rather large electric dipole moment in its excited state. Furthermore, values for the equilibrium constants and for the standard reaction enthalpies of both complex formation reactions are estimated from experimental data.

C-H Activation of Benzene by a Photoactivated Ni(II)(azide): Formation of a Transient Nickel Nitrido Complex.

PubMed

Vreeken, Vincent; Siegler, Maxime A; de Bruin, Bas; Reek, Joost N H; Lutz, Martin; van der Vlugt, Jarl Ivar

2015-06-08

Photochemical activation of nickel-azido complex 2 [Ni(N3)(PNP)] (PN(H)P=2,2'-di(isopropylphosphino)-4,4'-ditolylamine) in neat benzene produces diamagnetic complex 3 [Ni(Ph)(PN(P)N(H))], which is crystallographically characterized. DFT calculations support photoinitiated N2-loss of the azido complex to generate a rare, transient Ni(IV) nitrido species, which bears significant nitridyl radical character. Subsequent trapping of this nitrido through insertion into the Ni-P bond generates a coordinatively unsaturated Ni(II) imidophosphorane P=N donor. This species shows unprecedented reactivity toward 1,2-addition of a C-H bond of benzene to form 3. The structurally characterized chlorido complex 4 [Ni(Cl)(PN(P)N(H))] is generated by reaction of 3 with HCl or by direct photolysis of 2 in chlorobenzene. This is the first report of aromatic C-H bond activation by a trapped transient nitrido species of a late transition metal. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Benzene

Cancer.gov

Learn about benzene, a component of crude oil and other substances. Exposure to benzene may increase the risk of leukemia and other blood disorders. Among smokers, 90 percent of benzene exposure comes from smoking. Benzene may also be found in glues, adhesives, and paint or cleaning products.

Theoretical Study on the Complexes of Benzene with Isoelectronic Nitrogen-Containing Heterocycles

PubMed Central

Wang, Weizhou; Hobza, Pavel

2008-01-01

The π–π interactions between benzene and the aromatic nitrogen heterocycles pyridine, pyrimidine, 1,3,5-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, and 1,2,3,4,5-pentazine are systematically investigated. The T-shaped structures of all complexes studied exhibit a contraction of the C—H bond accompanied by a rather large blue shift (40–52 cm−1) of its stretching frequency, and they are almost isoenergetic with the corresponding displaced-parallel structures at reliable levels of theory. With increasing number of nitrogen atoms in the heterocycle, the geometries, frequencies, energies, percentage of s character at C, and the electron density in the C—H σ antibonding orbital of the complexes all increase or decrease systematically. Decomposition analysis of the total binding energy showed that for all the complexes, the dispersion energy is the dominant attractive contribution, and a rather large attraction originating from electrostatic contribution is compensated by its exchange counterpart. PMID:18389512

Risk assessment of occupational exposure to benzene using numerical simulation in a complex geometry of a reforming unit of petroleum refinery.

PubMed

Bayatian, Majid; Ashrafi, Khosro; Azari, Mansour Rezazadeh; Jafari, Mohammad Javad; Mehrabi, Yadollah

2018-04-01

There has been an increasing concern about the continuous and the sudden release of volatile organic pollutants from petroleum refineries and occupational and environmental exposures. Benzene is one of the most prevalent volatile compounds, and it has been addressed by many authors for its potential toxicity in occupational and environmental settings. Due to the complexities of sampling and analysis of benzene in routine and accidental situations, a reliable estimation of the benzene concentration in the outdoor setting of refinery using a computational fluid dynamics (CFD) could be instrumental for risk assessment of occupational exposure. In the present work, a computational fluid dynamic model was applied for exposure risk assessment with consideration of benzene being released continuously from a reforming unit of a refinery. For simulation of benzene dispersion, GAMBIT, FLUENT, and CFD post software are used as preprocessing, processing, and post-processing, respectively. Computational fluid dynamic validation was carried out by comparing the computed data with the experimental measurements. Eventually, chronic daily intake and lifetime cancer risk for routine operations through the two seasons of a year are estimated through the simulation model. Root mean square errors are 0.19 and 0.17 for wind speed and concentration, respectively. Lifetime risk assessments of workers are 0.4-3.8 and 0.0096-0.25 per 1000 workers in stable and unstable atmospheric conditions, respectively. Exposure risk is unacceptable for the head of shift work, chief engineer, and general workers in 141 days (38.77%) in a year. The results of this study show that computational fluid dynamics is a useful tool for modeling of benzene exposure in a complex geometry and can be used to estimate lifetime risks of occupation groups in a refinery setting.

UV-light promoted C-H bond activation of benzene and fluorobenzenes by an iridium(i) pincer complex.

PubMed

Hauser, Simone A; Emerson-King, Jack; Habershon, Scott; Chaplin, Adrian B

2017-03-28

Iridium(i) carbonyl complex [Ir(2,6-(P t Bu 2 CH 2 ) 2 C 6 H 3 )(CO)] undergoes reversible C-H bond activation of benzene and a series of fluorobenzenes on UV irradiation. Exclusive ortho-selectivity is observed in reactions of fluorobenzene and 1,2-difluorobenzene.

Substituent Effects in the Benzene Dimer are Due to Direct Interactions of the Substituents with the Unsubstituted Benzene

PubMed Central

Wheeler, Steven E.; Houk, K. N.

2009-01-01

The prevailing views of substituent effects in the sandwich configuration of the benzene dimer are flawed. For example, in the polar/π model of Cozzi and co-workers (J. Am. Chem. Soc. 1992, 114, 5729), electron-withdrawing substituents enhance binding in the benzene dimer by withdrawing electron density from the π-cloud of the substituted ring, reducing the repulsive electrostatic interaction with the non-substituted benzene. Conversely, electron-donating substituents donate excess electrons into the π-system and diminish the π-stacking interaction. We present computed interaction energies for the sandwich configuration of the benzene dimer and 24 substituted dimers, as well as sandwich complexes of substituted benzenes with perfluorobenzene. While the computed interaction energies correlate well with σm values for the substituents, interaction energies for related model systems demonstrate that this trend is independent of the substituted ring. Instead, the observed trends are consistent with direct electrostatic and dispersive interactions of the substituents with the unsubstituted ring. PMID:18652453

Models of S/π interactions in protein structures: Comparison of the H2S–benzene complex with PDB data

PubMed Central

Ringer, Ashley L.; Senenko, Anastasia; Sherrill, C. David

2007-01-01

S/π interactions are prevalent in biochemistry and play an important role in protein folding and stabilization. Geometries of cysteine/aromatic interactions found in crystal structures from the Brookhaven Protein Data Bank (PDB) are analyzed and compared with the equilibrium configurations predicted by high-level quantum mechanical results for the H2S–benzene complex. A correlation is observed between the energetically favorable configurations on the quantum mechanical potential energy surface of the H2S–benzene model and the cysteine/aromatic configurations most frequently found in crystal structures of the PDB. In contrast to some previous PDB analyses, configurations with the sulfur over the aromatic ring are found to be the most important. Our results suggest that accurate quantum computations on models of noncovalent interactions may be helpful in understanding the structures of proteins and other complex systems. PMID:17766371

Study of the electronic structure of electron accepting cyano-films: TCNQversusTCNE.

PubMed

Capitán, Maria J; Álvarez, Jesús; Navio, Cristina

2018-04-18

In this article, we perform systematic research on the electronic structure of two closely related organic electron acceptor molecules (TCNQ and TCNE), which are of technological interest due to their outstanding electronic properties. These studies have been performed from the experimental point of view by the use electron spectroscopies (XPS and UPS) and supported theoretically by the use of ab-initio DFT calculations. The cross-check between both molecules allows us to identify the characteristic electronic features of each part of the molecules and their contribution to the final electronic structure. We can describe the nature of the band gap of these materials, and we relate this with the appearance of the shake-up features in the core level spectra. A band bending and energy gap reduction of the aforementioned electronic structure in contact with a metal surface are seen in the experimental results as well in the theoretical calculations. This behavior implies that the TCNQ thin film accepts electrons from the metal substrate becoming a Schottky n-junction.

Ab initio investigation of electric and magnetic dipole electronic transitions in the complex of oxygen with benzene.

PubMed

Valiev, R R; Minaev, B F

2016-09-01

The electric dipole transitions between pure spin and mixed spin electronic states are calculated at the XMC-QDPT2 and MCSCF levels of theory, respectively, for different intermolecular distances of the C6H6 and O2 collisional complex. The magnetic dipole transition moment between the mixed-spin ground ("triplet") and the first excited ("singlet") states is calculated by quadratic response at MCSCF level of theory. The obtained results confirm the theory of intensity borrowing and increasing the intensity of electronic transitions in the C6H6 + O2 collision. The calculation of magnetically induced current density is performed for benzene molecule being in contact with O2 at the distances from 3.5 to 4.5 Å. The calculation shows that the aromaticity of benzene is rising due to the conjugation of π-MOs of both molecules. The C6H6 + O2 complex becomes nonaromatic at the short distances (r < 3.5 Å). The computation of static polarizability in the excited electronic states of the C6H6 + O2 collisional complex at various distances supports the theory of red solvatochromic shift of the a → X band. Graphical abstract The C6H6+ O2 collisional complex.

Structures, vibrational frequencies, and infrared spectra of the hexa-hydrated benzene clusters

NASA Astrophysics Data System (ADS)

Lee, Jin Yong; Kim, Jongseob; Lee, Han Myoung; Tarakeshwar, P.; Kim, Kwang S.

2000-10-01

The water hexamer is known to have a number of isoenergetic structures. The first experimental identification of the O-H stretching vibrational spectra of the water hexamer was done in the presence of benzene. It was followed by the identification of the pure water hexamer structure by vibration-rotational tunneling (VRT) spectroscopy. Although both experiments seem to have located only the Cage structure, the structure of the benzene-water hexamer complex is not clearly known, and the effect of benzene in the water hexamer is unclear. In particular, it is not obvious how the energy difference between nearly isoenergetic water hexamer conformers changes in the presence of benzene. Thus, we have compared the benzene complexes with four low-lying isoenergetic water hexamers, Ring, Book, Cage, and Prism structures, using ab initio calculations. We also investigated the effects of the presence of benzene on the structures, harmonic vibrational frequencies, and infrared (IR) intensities for the four low-lying energy conformers. There is little change in the structure of the water hexamer upon its interaction with the benzene molecule. Hence the deformation energies are very small. The dominant contribution to the benzene-water cluster interaction mainly comes from the π-H interactions between benzene and a single water molecule. As a result of this π-H interaction, O-Hπ bond length increases and the corresponding stretching vibrational frequencies are redshifted. The IR spectral features of both (H2O)6 and benzene-(H2O)6 are quite similar. From both the energetics and the comparison of calculated and experimental spectra of the benzene-(H2O)6, the water structure in these complexes is found to have the Cage form. In particular, among the four different Cage structures, only one conformer matches the experimental O-H vibrational frequencies.

Complex magnetic orders in small cobalt-benzene molecules.

PubMed

González, J W; Alonso-Lanza, T; Delgado, F; Aguilera-Granja, F; Ayuela, A

2017-06-07

Organometallic clusters based on transition metal atoms are interesting because of their possible applications in spintronics and quantum information processing. In addition to the enhanced magnetism at the nanoscale, the organic ligands may provide a natural shield against unwanted magnetic interactions with the matrices required for applications. Here we show that the organic ligands may lead to non-collinear magnetic order as well as the expected quenching of the magnetic moments. We use different density functional theory (DFT) methods to study the experimentally relevant three cobalt atoms surrounded by benzene rings (Co 3 Bz 3 ). We found that the benzene rings induce a ground state with non-collinear magnetization, with the magnetic moments localized on the cobalt centers and lying on the plane formed by the three cobalt atoms. We further analyze the magnetism of such a cluster using an anisotropic Heisenberg model where the involved parameters are obtained by a comparison with the DFT results. These results may also explain the recent observation of the null magnetic moment of Co 3 Bz 3 + . Moreover, we propose an additional experimental verification based on electron paramagnetic resonance.

Structure and stability of fluorine-substituted benzene-argon complexes: The decisive role of exchange-repulsion and dispersion interactions

NASA Astrophysics Data System (ADS)

Tarakeshwar, P.; Kim, Kwang S.; Kraka, Elfi; Cremer, Dieter

2001-10-01

The van der Waals complexes benzene-argon (BAr), fluorobenzene-argon (FAr), p-difluorobenzene-argon (DAr) are investigated at the second-order Møller-Plesset (MP2) level of theory using the 6-31+G(d), cc-pVDZ, aug-cc-pVTZ, and [7s4p2d1f/4s3p1d/3s1p] basis sets. Geometries, binding energies, harmonic vibrational frequencies, and density distribution are calculated where basis set superposition errors are corrected with the counterpoise method. Binding energies turn out to be almost identical (MP2/[7s4p2d1f/4s3p1d/3s1p]: 408, 409, 408 cm-1) for BAr, FAr, and DAr. Vibrationally corrected binding energies (357, 351, 364 cm-1) agree well with experimental values (340, 344, and 339 cm-1). Symmetry adapted perturbation theory (SAPT) is used to decompose binding energies and to examine the influence of attractive and repulsive components. Fluorine substituents lead to a contraction of the π density of the benzene ring, thus reducing the destabilizing exchange-repulsion and exchange-induction effects. At the same time, both the polarizing power and the polarizability of the π-density of the benzene derivative decreases thus reducing stabilizing induction and dispersion interactions. Stabilizing and destabilizing interactions largely cancel each other out to give comparable binding energies. The equilibrium geometry of the Ar complex is also a result of the decisive influence of exchange-repulsion and dispersive interactions.

Electromers of the benzene dimer radical cation.

PubMed

Błoch-Mechkour, Anna; Bally, Thomas

2015-04-28

The well-studied benzene dimer radical cation, which is prototypical for this class of species, has been reinvestigated computationally. Thereby it turned out that both the σ-hemibonded and the half-shifted sandwich structures of the benzene dimer cation, which had been independently proposed, represent stationary points on the B2PLYP-D potential energy surfaces. However, these structures belong to distinct electronic states, both of which are associated with potential surfaces that are very flat with regard to rotation of the two benzene rings in an opposite sense relative to each other. The surfaces of these two "electromers" of the benzene dimer cation are separated by only 3-4 kcal mol(-1) and do not intersect along the rotation coordinate, which represents a rather unique electronic structure situation. When moving on either of the two surfaces the title complex is an extremely fluxional species, in spite of its being bound by over 20 kcal mol(-1).

Selective hydroxylation of benzene derivatives and alkanes with hydrogen peroxide catalysed by a manganese complex incorporated into mesoporous silica-alumina.

PubMed

Aratani, Yusuke; Yamada, Yusuke; Fukuzumi, Shunichi

2015-03-18

Selective hydroxylation of benzene derivatives and alkanes to the corresponding phenol and alcohol derivatives with hydrogen peroxide was efficiently catalysed by a manganese tris(2-pyridylmethyl)amine (tpa) complex ([(tpa)Mn(II)](2+)) incorporated into mesoporous silica-alumina with highly acidic surfaces in contrast to the reactions in a homogeneous solution where [(tpa)Mn(II)](2+) was converted catalytically to a much less active bis(μ-oxo)dimanganese(III,IV) complex.

13C and 1H nuclear magnetic resonance of methyl-substituted acetophenones and methyl benzoates: steric hindrance and inhibited conjugation.

PubMed

Budesínský, Milos; Kulhánek, Jirí; Böhm, Stanislav; Cigler, Petr; Exner, Otto

2004-10-01

The 1H and 13C NMR spectra of 14 methyl-substituted acetophenones and 14 methyl-substituted methyl benzoates were assigned and interpreted with respect to the conformation of the C(ar)-C(O) bond. The substituent effects are proportional in the two series and can be divided into polar and steric: each has different effects on the 13C SCS of the individual atoms. In the case of C atoms C(O), C(1) and CH3(CO), the steric effects were quantitatively separated by comparing SCS in the ortho and para positions. The steric effects are proportional for the individual C atoms and also to steric effects estimated from other physical quantities. However, they do not depend simply on the angle of torsion phi of the functional group as anticipated hitherto. A better description distinguishes two classes of compounds: sterically not hindered or slightly hindered planar molecules and strongly sterically hindered, markedly non-planar. In order to confirm this reasoning without empirical correlations, the J(C,C) coupling constants were measured for three acetophenone derivatives labeled with 13C in the acetyl methyl group. The constants confirm unambiguously the conformation of 2-methylacetophenone; their zero values are in accord with the conformation of 2,6-dimethylacetophenone. The zero values in the unsubstituted acetophenone are at variance with previous erroneous report but all J(C,C) values are in accord with calculations at the B3LYP/6-311++G(2d,2p)//B3LYP/6-311+G(d,p) level. Copyright 2004 John Wiley & Sons, Ltd.

A quantitative method for estimating dermal benzene absorption from benzene-containing hydrocarbon liquids.

PubMed

Petty, Stephen E; Nicas, Mark; Boiarski, Anthony A

2011-01-01

This study examines a method for estimating the dermal absorption of benzene contained in hydrocarbon liquids that contact the skin. This method applies to crude oil, gasoline, organic solvents, penetrants, and oils. The flux of benzene through occluded skin as a function of the percent vol/vol benzene in the liquid is derived by fitting a curve to experimental data; the function is supralinear at benzene concentrations < or = 5% vol/vol. When a liquid other than pure benzene is on nonoccluded skin, benzene may preferentially evaporate from the liquid, which thereby decreases the benzene flux. We present a time-averaging method here for estimating the reduced dermal flux during evaporation. Example calculations are presented for benzene at 2% vol/vol in gasoline, and for benzene at 0.1% vol/vol in a less volatile liquid. We also discuss other factors affecting dermal absorption.

Formation of a new benzene-ethane co-crystalline structure under cryogenic conditions.

PubMed

Vu, Tuan Hoang; Cable, Morgan L; Choukroun, Mathieu; Hodyss, Robert; Beauchamp, Patricia

2014-06-12

We report the first experimental finding of a solid molecular complex between benzene and ethane, two small apolar hydrocarbons, at atmospheric pressure and cryogenic temperatures. Considerable amounts of ethane are found to be incorporated inside the benzene lattice upon the addition of liquid ethane onto solid benzene at 90-150 K, resulting in formation of a distinctive co-crystalline structure that can be detected via micro-Raman spectroscopy. Two new features characteristic of these co-crystals are observed in the Raman spectra at 2873 and 1455 cm(-1), which are red-shifted by 12 cm(-1) from the υ1 (a1g) and υ11 (eg) stretching modes of liquid ethane, respectively. Analysis of benzene and ethane vibrational bands combined with quantum mechanical modeling of isolated molecular dimers reveal an interaction between the aromatic ring of benzene and the hydrogen atoms of ethane in a C-H···π fashion. The most favored configuration for the benzene-ethane dimer is the monodentate-contact structure, with a calculated interaction energy of 9.33 kJ/mol and an equilibrium bonding distance of 2.66 Å. These parameters are comparable to those for a T-shaped co-crystalline complex between benzene and acetylene that has been previously reported in the literature. These results are relevant for understanding the hydrocarbon cycle of Titan, where benzene and similar organics may act as potential hydrocarbon reservoirs due to this incorporation mechanism.

Urinary excretion of unmetabolized benzene as an indicator of benzene exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghittori, S.; Fiorentino, M.L.; Maestri, L.

1993-03-01

Benzene concentrations in urine samples (Cu, ng/L) from 110 workers exposed to benzene in chemical plants and gasoline pumps were determined by injecting urine supernate into a gas chromatograph. The urine was saturated with anhydrous N2SO4 to facilitate the passage of benzene in the air over the urine. The solvent was stripped from the urine surface and concentrated on an adsorbent substrate (Carbotrap tube) by means of a suction pump (flow rate 150 ml/m). Wash-up of the head space was achieved by simultaneous intake of filtered air through charcoal. Benzene was thermically desorbed and injected in a column (thermal tubemore » disorder, Supelco; 370 degrees C thermal flash; borosilicate capillary glass column SPB-1, 60 m length, 0.75 mm ID, 1 microns film thickness; GC Dani 8580-FID). Benzene concentrations in the urine from 40 non-exposed subjects (20 smokers > 20 cigarette/d and 20 nonsmokers) were also determined [median value of 790 ng/L (10.17 nmol/L) and 131 ng/L (1.70 nmol/L), respectively]. The 8-h time-weighted exposure intensity (Cl, micrograms/m3) of individual workers was monitored by means of charcoal tubes. The median value for exposure to benzene was 736 micrograms/m3 (9.42 mumol/m3) [geometric standard deviation (GSD) = 2.99; range 64 micrograms/m3 (0.82 mumol/m3) to 13,387 micrograms/m3 (171.30 mumol/m3)]. The following linear correlation was found between benzene concentrations in urine (Cu, ng/L) and benzene concentrations in the breathing zone (Cl, micrograms/m3): log(Cu) = 0.645 x log(Cl) + 1.399 r = .559, n = 110, p < .0001 With exclusion of workers who smoked from the study, the correlation between air benzene concentration and benzene measured in urine was: log(Cu) = 0.872 x log(Cl) + 0.6 r = .763, n = 63, p < .0001 The study results indicate that the urinary level of benzene is an indicator of occupational exposure to benzene.« less

Identification of human cell responses to benzene and benzene metabolites.

PubMed

Gillis, Bruce; Gavin, Igor M; Arbieva, Zarema; King, Stephen T; Jayaraman, Sundararajan; Prabhakar, Bellur S

2007-09-01

Benzene is a common air pollutant and confirmed carcinogen, especially in reference to the hematopoietic system. In the present study we analyzed cytokine/chemokine production by, and gene expression induction in, human peripheral blood mononuclear cells upon their exposure to the benzene metabolites catechol, hydroquinone, 1,2,4-benzenetriol, and p-benzoquinone. Protein profiling showed that benzene metabolites can stimulate the production of chemokines, the proinflammatory cytokines TNF-alpha and IL-6, and the Th2 cytokines IL-4 and IL-5. Activated cells showed concurrent suppression of anti-inflammatory cytokine IL-10 expression. We also identified changes in global gene expression patterns in response to benzene metabolite challenges by using high-density oligonucleotide microarrays. Treatment with 1,2,4-benzenetriol resulted in the suppression of genes related to the regulation of protein expression and a concomitant activation of genes that encode heat shock proteins and cytochrome P450 family members. Protein and gene expression profiling identified unique human cellular responses upon exposure to benzene and benzene metabolites.

Percutaneous penetration of benzene and benzene contained in solvents used in the rubber industry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maibach, H.I.; Anjo, D.M.

1981-09-01

Penetration of benzene through the skin of the rhesus monkey was determined using /sup 14/C-benzene, and quantitating the labelled metabolites in urine. The modes of application and amounts of benzene that penetrated the skin (indicated in parentheses) are as follows: (1) a single, direct cutaneous application of liquid benzene (0.172 +/- 0.139%); (2) a single application of benzene-containing (0.36%) solvent (0.0805 +/- 0.0306%); (3) multiple washes with full-strength benzene (0.848 +/- 0.0806%); (4) multiple washes with the benzene-containing (0.35%) solvent (0.431 +/- 0.258%); (5) removal of the stratum corneum followed by application of full-strength benzene (0.09 +/- 0.627%); and (6)more » application of benzene to the palmar surface (0.651 +/- 0.482%). Until more complete human data becomes available, benzene penetration in the monkey may be used to estimate penetration in man, both for industrial hygiene purposes and general toxicological use.« less

Benzene and cyclohexane separation using 1-butyl-3-methylimidazolium thiocyanate

NASA Astrophysics Data System (ADS)

Gonfa, Girma; Ismail, Marhaina; Bustam, Mohamad Azmi

2017-09-01

Cyclohexane is mainly produced by catalytic hydrogenation of benzene. Removal of unreacted benzene from the product stream is very important in this process. However, due to their close boiling points and azeotrope formation, it is very difficult to separate cyclohexane and benzene by conventional distillation. Currently, special separation processes such as processes extractive distillation is commercially used for this separation. However, this extractive distillation suffers from process complexity and higher energy consumption due to their low extractive selectivity of molecular entrainers used. The aim of the present work is to investigate the applicability of ionic liquids as entrainer in extractive distillation of benzene and cyclohexane mixture. In this study, we investigated 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) ionic liquid for separation of benzene and cyclohexane by measuring the Vapor Liquid Equilibrium data of the two components in the presence of the ionic liquid. As green and potential environmentally friendly solvents, ionic liquids have attracted increasing attention as alternative conventional entrainers in extractive distillation. Isothermal Vapor Liquid Equilibrium for the benzene + cyclohexane + [BMIM][SCN] ternary system was obtained at 353.15 K using a Head Space Gas Chromatography. The addition of [BMIM][SCN] breaks the benzene-cyclohexane azeotrope and increased the relative volatility cyclohexane to benzene in the mixture. The effect of [BMIM][SCN] on the relative volatility cyclohexane to benzene was studied at various benzene and cyclohexane compositions and solvent to feed ratios. The performance of [BMIM][SCN] was compared with typical conventional solvents, dimethylformamide (DMF) and dimethylsulfoxide (DMSO). The results show that the relative volatility of cyclohexane to benzene in the presence of [BMIM][SCN] is higher compared that of DMSO and DMF.

Benzene oxidation coupled to sulfate reduction

USGS Publications Warehouse

Lovley, D.R.; Coates, J.D.; Woodward, J.C.; Phillips, E.J.P.

1995-01-01

Highly reduced sediments from San Diego Bay, Calif., that were incubated under strictly anaerobic conditions metabolized benzene within 55 days when they were exposed initially to I ??M benzene. The rate of benzene metabolism increased as benzene was added back to the benzene-adapted sediments. When a [14C]benzene tracer was included with the benzene added to benzene-adapted sediments, 92% of the added radioactivity was recovered as 14CO2. Molybdate, an inhibitor of sulfate reduction, inhibited benzene uptake and production of 14CO2 from [14C]benzene. Benzene metabolism stopped when the sediments became sulfate depleted, and benzene uptake resumed when sulfate was added again. The stoichiometry of benzene uptake and sulfate reduction was consistent with the hypothesis that sulfate was the principal electron acceptor for benzene oxidation. Isotope trapping experiments performed with [14C]benzene revealed that there was no production of such potential extracellular intermediates of benzene oxidation as phenol, benzoate, p-hydroxybenzoate, cyclohexane, catechol, and acetate. The results demonstrate that benzene can be oxidized in the absence of O2, with sulfate serving as the electron acceptor, and suggest that some sulfate reducers are capable of completely oxidizing benzene to carbon dioxide without the production of extracellular intermediates. Although anaerobic benzene oxidation coupled to chelated Fe(III) has been documented previously, the study reported here provides the first example of a natural sediment compound that can serve as an electron acceptor for anaerobic benzene oxidation.

Anaerobic Benzene Degradation in Petroleum-Contaminated Aquifer Sediments after Inoculation with a Benzene-Oxidizing Enrichment

PubMed Central

Weiner, Jonathan M.; Lovley, Derek R.

1998-01-01

Sediments from the sulfate-reduction zone of a petroleum-contaminated aquifer, in which benzene persisted, were inoculated with a benzene-oxidizing, sulfate-reducing enrichment from aquatic sediments. Benzene was degraded, with apparent growth of the benzene-degrading population over time. These results suggest that the lack of benzene degradation in the sulfate-reduction zones of some aquifers may result from the failure of the appropriate benzene-degrading sulfate reducers to colonize the aquifers rather than from environmental conditions that are adverse for anaerobic benzene degradation. PMID:9464422

Studies on the weak interactions and CT complex formations between chloranilic acid, 2,3-dichloro-5,6-dicyano-p-benzoquinone, tetracyanoethylene and papaverine in acetonitrile and their thermodynamic properties, theoretically, spectrophotometrically aided by FTIR

NASA Astrophysics Data System (ADS)

Datta, Asim Sagar; (Chattaraj), Seema Bagchi; Chakrabortty, Ashutosh; Lahiri, Sujit Chandra

2015-07-01

Spectrophotometric, FTIR and theoretical studies of the charge-transfer complexes between mild narcotic drug papaverine and the acceptors chloranilic acid (Cl-A), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tetracyanoethylene (TCNE) in acetonitrile, their association constants, thermodynamic (ΔG0, ΔH0 and ΔS0) and other related properties had been described. Papaverine was found to form colored charge-transfer complexes with Cl-A, DDQ and TCNE in acetonitrile. The absorption maxima of the complexes were 518.5, 584.0 and 464.0 nm for Cl-A complex, DDQ complex, and TCNE complex respectively. The compositions of the papaverine complexes were determined to be 1:1 from Job's method of continuous variation. Solid complexes formed between papaverine and the acceptors were isolated. Comparison of the FTIR spectra of the solid complexes between papaverine and the acceptors and their constituents showed considerable shift in absorption peaks, changes in intensities of the peaks and formation of the new bands on complexation. However, no attempt has been made to purify the complexes and study the detailed spectra both theoretically and experimentally. The energies hνCT of the charge-transfer complexes were compared with the theoretical values of hνCT of the complexes obtained from HOMO and LUMO of the donor and the acceptors. The reasons for the differences in hνCT values were explained. Density function theory was used for calculation. hνCT (experimental) values of the transition energies of the complexes in acetonitrile differed from hνCT (theoretical) values. IDV value of papaverine was calculated. Charge-transfer complexes were assumed to be partial electrovalent compounds with organic dative ions D+ and A- (in the excited state) and attempts had been made to correlate the energy changes for the formation of the complexes with the energy changes for the formation of electrovalent compounds between M+ and X- ions.

Genome-Wide Functional Profiling Reveals Genes Required for Tolerance to Benzene Metabolites in Yeast

PubMed Central

North, Matthew; Tandon, Vickram J.; Thomas, Reuben; Loguinov, Alex; Gerlovina, Inna; Hubbard, Alan E.; Zhang, Luoping; Smith, Martyn T.; Vulpe, Chris D.

2011-01-01

Benzene is a ubiquitous environmental contaminant and is widely used in industry. Exposure to benzene causes a number of serious health problems, including blood disorders and leukemia. Benzene undergoes complex metabolism in humans, making mechanistic determination of benzene toxicity difficult. We used a functional genomics approach to identify the genes that modulate the cellular toxicity of three of the phenolic metabolites of benzene, hydroquinone (HQ), catechol (CAT) and 1,2,4-benzenetriol (BT), in the model eukaryote Saccharomyces cerevisiae. Benzene metabolites generate oxidative and cytoskeletal stress, and tolerance requires correct regulation of iron homeostasis and the vacuolar ATPase. We have identified a conserved bZIP transcription factor, Yap3p, as important for a HQ-specific response pathway, as well as two genes that encode putative NAD(P)H:quinone oxidoreductases, PST2 and YCP4. Many of the yeast genes identified have human orthologs that may modulate human benzene toxicity in a similar manner and could play a role in benzene exposure-related disease. PMID:21912624

BENZENE OXIDE PROTEIN ADDUCTS AS BIOMARKERS OF BENZENE EXPOSURE

EPA Science Inventory

Benzene is known to be hematotoxic and carcinogenic in animals and humans. While metabolism is required for toxicity, the identity of the ultimate carcinogen(s) remains unknown. Benzene oxide (BO) is the first and most abundant of the metabolites, but very little is known about...

Resonance Raman study of a two-chromophore system. The 2:1 complex of hexamethylbenzene with tetracyanoethylene

NASA Astrophysics Data System (ADS)

Mark Britt, B.; McHale, Jeanne L.

1997-05-01

Raman excitation profiles are presented for the 2:1 electron donor-acceptor (EDA) complex of hexamethylbenzene (HMB) and tetracyanoethylene (TCNE) in cyclohexane. Though the absorption and Raman spectra of the 1:1 and 2:1 complexes are similar, distinct differences are found in the Raman excitation profiles (REPs) of vibrational modes common to both systems. REPs of the 2:1 complex show intensity cancellation that is taken as evidence for interference of two charge-transfer excited states. The implications of the observed spectra concerning excited state electron delocalization are considered.

Anaerobic benzene degradation by bacteria

PubMed Central

Vogt, Carsten; Kleinsteuber, Sabine; Richnow, Hans‐Hermann

2011-01-01

Summary Benzene is a widespread and toxic contaminant. The fate of benzene in contaminated aquifers seems to be primarily controlled by the abundance of oxygen: benzene is aerobically degraded at high rates by ubiquitous microorganisms, and the oxygen‐dependent pathways for its breakdown were elucidated more than 50 years ago. In contrast, benzene was thought to be persistent under anoxic conditions until 25 years ago. Nevertheless, within the last 15 years, several benzene‐degrading cultures have been enriched under varying electron acceptor conditions in laboratories around the world, and organisms involved in anaerobic benzene degradation have been identified, indicating that anaerobic benzene degradation is a relevant environmental process. However, only a few benzene degraders have been isolated in pure culture so far, and they all use nitrate as an electron acceptor. In some highly enriched strictly anaerobic cultures, benzene has been described to be mineralized cooperatively by two or more different organisms. Despite great efforts, the biochemical mechanism by which the aromatic ring of benzene is activated in the absence of oxygen is still not fully elucidated; methylation, hydroxylation and carboxylation are discussed as likely reactions. This review summarizes the current knowledge about the ‘key players’ of anaerobic benzene degradation under different electron acceptor conditions and the possible pathway(s) of anaerobic benzene degradation. PMID:21450012

Binding of Alkali Metal Ions with 1,3,5-Tri(phenyl)benzene and 1,3,5-Tri(naphthyl)benzene: The Effect of Phenyl and Naphthyl Ring Substitution on Cation-π Interactions Revealed by DFT Study.

PubMed

Mirchi, Ali; Sizochenko, Natalia; Dinadayalane, Tandabany; Leszczynski, Jerzy

2017-11-22

The effect of substitution of phenyl and naphthyl rings to benzene was examined to elucidate the cation-π interactions involving alkali metal ions with 1,3,5-tri(phenyl)benzene (TPB) and 1,3,5-tri(naphthyl)benzene (TNB). Benzene, TPB, and four TNB isomers (with ααα, ααβ, αββ, and βββ types of fusion) and their complexes with Li + , Na + , K + , Rb + , and Cs + were optimized using DFT approach with B3LYP and M06-2X functionals in conjunction with the def2-QZVP basis set. Higher relative stability of β,β,β-TNB over α,α,α-TNB can be attributed to peri repulsion, which is defined as the nonbonding repulsive interaction between substituents in the 1- and the 8-positions on the naphthalene core. Binding energies, distances between ring centroid and the metal ions, and the distance to metal ions from the center of other six-membered rings were compared for all complexes. Our computational study reveals that the binding affinity of alkali metal cations increases significantly with the 1,3,5-trisubstitution of phenyl and naphthyl rings to benzene. The detailed computational analyses of geometries, partial charges, binding energies, and ligand organization energies reveal the possibility of favorable C-H···M + interactions when a α-naphthyl group exists in complexes of TNB structures. Like benzene-alkali metal ion complexes, the binding affinity of metal ions follows the order: Li + > Na + > K + > Rb + > Cs + for any considered 1,3,5-trisubstituted benzene systems. In case of TNB, we found that the strength of interactions increases as the fusion point changes from α to β position of naphthalene.

The toxicity of benzene and its metabolism and molecular pathology in human risk assessment.

PubMed Central

Yardley-Jones, A; Anderson, D; Parke, D V

1991-01-01

Benzene, a common industrial chemical and a component of gasoline, is radiomimetic and exposure may lead progressively to aplastic anaemia, leukaemia, and multiple myeloma. Although benzene has been shown to cause many types of genetic damage, it has consistently been classified as a non-mutagen in the Ames test, possibly because of the inadequacy of the S9 microsomal activation system. The metabolism of benzene is complex, yielding glucuronide and sulphate conjugates of phenol, quinol, and catechol, L-phenylmercapturic acid, and muconaldehyde and trans, trans-muconic acid by ring scission. Quinol is oxidised to p-benzoquinone, which binds to vital cellular components or undergoes redox cycling to generate oxygen radicals; muconaldehyde, like p-benzoquinone, is toxic through depletion of intracellular glutathione. Exposure to benzene may also induce the microsomal mixed function oxidase, cytochrome P450 IIE1, which is probably responsible for the oxygenation of benzene, but also has a propensity to generate oxygen radicals. The radiomimetic nature of benzene and its ability to induce different sites of neoplasia indicate that formation of oxygen radicals is a major cause of benzene toxicity, which involves multiple mechanisms including synergism between arylating and glutathione-depleting reactive metabolites and oxygen radicals. The occupational exposure limit in the United Kingdom (MEL) and the United States (PEL) was 10 ppm based on the association of benzene exposure with aplastic anaemia, but recently was lowered to 5 ppm and 1 ppm respectively, reflecting a concern for the risk of neoplasia. The American Conference of Governmental Industrial Hygienists (ACGIH) has even more recently recommended that, as benzene is considered an A1 carcinogen, the threshold limit value (TLV) should be decreased to 0.1 ppm. Only one study in man, based on nine cases of benzene associated fatal neoplasia, has been considered suitable for risk assessment. Recent re-evaluation of

MEASUREMENT OF BENZENE OXIDE IN THE BLOOD OF RATS FOLLOWING ADMINISTRATION OF BENZENE

EPA Science Inventory

Although it is generally assumed that metabolism of benzene proceeds through an initial step involving oxidation to benzene oxide (BO) by CYP450 in the liver, the production of BO has never been unambiguously confirmed in animals dosed with benzene. Furthermore, prevailing hypo...

Benzene Degradation by a Variovorax Species within a Coal Tar-Contaminated Groundwater Microbial Community.

PubMed

Posman, Kevin M; DeRito, Christopher M; Madsen, Eugene L

2017-02-15

Investigations of environmental microbial communities are crucial for the discovery of populations capable of degrading hazardous compounds and may lead to improved bioremediation strategies. The goal of this study was to identify microorganisms responsible for aerobic benzene degradation in coal tar-contaminated groundwater. Benzene degradation was monitored in laboratory incubations of well waters using gas chromatography mass spectrometry (GC-MS). Stable isotope probing (SIP) experiments using [ 13 C]benzene enabled us to obtain 13 C-labled community DNA. From this, 16S rRNA clone libraries identified Gammaproteobacteria and Betaproteobacteria as the active benzene-metabolizing microbial populations. Subsequent cultivation experiments yielded nine bacterial isolates that grew in the presence of benzene; five were confirmed in laboratory cultures to grow on benzene. The isolated benzene-degrading organisms were genotypically similar (>97% 16S rRNA gene nucleotide identities) to the organisms identified in SIP experiments. One isolate, Variovorax MAK3, was further investigated for the expression of a putative aromatic ring-hydroxylating dioxygenase (RHD) hypothesized to be involved in benzene degradation. Microcosm experiments using Variovorax MAK3 revealed a 10-fold increase in RHD (Vapar_5383) expression, establishing a link between this gene and benzene degradation. Furthermore, the addition of Variovorax MAK3 to microcosms prepared from site waters accelerated community benzene degradation and correspondingly increased RHD gene expression. In microcosms using uninoculated groundwater, quantitative (q)PCR assays (with 16S rRNA and RDH genes) showed that Variovorax was present and responsive to added benzene. These data demonstrate how the convergence of cultivation-dependent and -independent techniques can boost understandings of active populations and functional genes in complex benzene-degrading microbial communities. Benzene is a human carcinogen whose

Benzene Degradation by a Variovorax Species within a Coal Tar-Contaminated Groundwater Microbial Community

PubMed Central

Posman, Kevin M.; DeRito, Christopher M.

2016-01-01

ABSTRACT Investigations of environmental microbial communities are crucial for the discovery of populations capable of degrading hazardous compounds and may lead to improved bioremediation strategies. The goal of this study was to identify microorganisms responsible for aerobic benzene degradation in coal tar-contaminated groundwater. Benzene degradation was monitored in laboratory incubations of well waters using gas chromatography mass spectrometry (GC-MS). Stable isotope probing (SIP) experiments using [13C]benzene enabled us to obtain 13C-labled community DNA. From this, 16S rRNA clone libraries identified Gammaproteobacteria and Betaproteobacteria as the active benzene-metabolizing microbial populations. Subsequent cultivation experiments yielded nine bacterial isolates that grew in the presence of benzene; five were confirmed in laboratory cultures to grow on benzene. The isolated benzene-degrading organisms were genotypically similar (>97% 16S rRNA gene nucleotide identities) to the organisms identified in SIP experiments. One isolate, Variovorax MAK3, was further investigated for the expression of a putative aromatic ring-hydroxylating dioxygenase (RHD) hypothesized to be involved in benzene degradation. Microcosm experiments using Variovorax MAK3 revealed a 10-fold increase in RHD (Vapar_5383) expression, establishing a link between this gene and benzene degradation. Furthermore, the addition of Variovorax MAK3 to microcosms prepared from site waters accelerated community benzene degradation and correspondingly increased RHD gene expression. In microcosms using uninoculated groundwater, quantitative (q)PCR assays (with 16S rRNA and RDH genes) showed that Variovorax was present and responsive to added benzene. These data demonstrate how the convergence of cultivation-dependent and -independent techniques can boost understandings of active populations and functional genes in complex benzene-degrading microbial communities. IMPORTANCE Benzene is a human

Facts about Benzene

MedlinePlus

... Disposal of Contaminated Clothing .” If you think your water supply may have benzene in it, drink bottled water until you are sure your water supply is safe. If someone has swallowed benzene, do ...

46 CFR 151.05-2 - Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or...

Code of Federal Regulations, 2014 CFR

2014-10-01

... benzene and benzene containing cargoes, or butyl acrylate cargoes. 151.05-2 Section 151.05-2 Shipping... Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or butyl acrylate cargoes. A tank barge certificated to carry benzene and benzene containing cargoes or butyl...

46 CFR 151.05-2 - Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or...

Code of Federal Regulations, 2010 CFR

2010-10-01

... benzene and benzene containing cargoes, or butyl acrylate cargoes. 151.05-2 Section 151.05-2 Shipping... Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or butyl acrylate cargoes. A tank barge certificated to carry benzene and benzene containing cargoes or butyl...

46 CFR 151.05-2 - Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or...

Code of Federal Regulations, 2012 CFR

2012-10-01

... benzene and benzene containing cargoes, or butyl acrylate cargoes. 151.05-2 Section 151.05-2 Shipping... Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or butyl acrylate cargoes. A tank barge certificated to carry benzene and benzene containing cargoes or butyl...

46 CFR 151.05-2 - Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or...

Code of Federal Regulations, 2013 CFR

2013-10-01

... benzene and benzene containing cargoes, or butyl acrylate cargoes. 151.05-2 Section 151.05-2 Shipping... Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or butyl acrylate cargoes. A tank barge certificated to carry benzene and benzene containing cargoes or butyl...

46 CFR 151.05-2 - Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or...

Code of Federal Regulations, 2011 CFR

2011-10-01

... benzene and benzene containing cargoes, or butyl acrylate cargoes. 151.05-2 Section 151.05-2 Shipping... Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or butyl acrylate cargoes. A tank barge certificated to carry benzene and benzene containing cargoes or butyl...

Imaging charge transfer in a cation-π system: velocity-map imaging of Ag(+)(benzene) photodissociation.

PubMed

Maner, Jonathon A; Mauney, Daniel T; Duncan, Michael A

2015-11-19

Ag(+)(benzene) complexes are generated in the gas phase by laser vaporization and mass selected in a time-of-flight spectrometer. UV laser excitation at either 355 or 266 nm results in dissociative charge transfer (DCT), leading to neutral silver atom and benzene cation products. Kinetic energy release in translationally hot benzene cations is detected using a new instrument designed for photofragment imaging of mass-selected ions. Velocity-map imaging and slice imaging techniques are employed. In addition to the expected translational energy release, DCT of Ag(+)(benzene) produces a distribution of internally hot benzene cations. Compared with experiments at 355 nm, 266 nm excitation produces only slightly higher translational excitation and a much greater fraction of internally hot benzene ions. The maximum kinetic energy release in the photodissociation sets an upper limit on the Ag(+)(benzene) dissociation energy of 32.8 (+1.4/-1.5) kcal/mol.

On the Performance of Local Density Approximation in Describing the Adsorption of Electron Donating/Accepting Molecules on Graphene

PubMed Central

Wang, Yixuan; Xu, Zhenfeng; Moe, Yin N.

2012-01-01

In order to asses performance of the LDA in describing physisorption on graphene, adsorptions of TCNE, TCNQ, TNF, TTF, and DMPD as well as four benzene derivatives on C54H18 and C110H30 were explored with a variety of DFTs such as MPWB1K, M06-2X, PBE-D and LSDA. Although it is well known that the LDA considerably overestimate non-covalent interaction, the LSDA predicted adsorption energies except for TCNE on C110H30 are systematically lower than those from the M06-2X by 0.4–3.2 kcal/mol, and they are more significantly lower than those from the PBE-D for all the molecules by 3–6 kcal/mol. However, the LSDA adsorption energy sequence is consistent with that from the PBE-D, TNF~TCNQ>TCNE~DMPD>TTF. Moreover, the domain interaction between the electron donor and acceptor molecules with graphene through cooperative π···π, C-H···π and N-H···π were visualized with sign(λ2)×ρ, and the relationships between the binding energy with London force, molecular electronegativity, and frontier orbital level were extensively discussed. PMID:23180902

Biomarkers of susceptibility following benzene exposure: influence of genetic polymorphisms on benzene metabolism and health effects.

PubMed

Carbonari, Damiano; Chiarella, Pieranna; Mansi, Antonella; Pigini, Daniela; Iavicoli, Sergio; Tranfo, Giovanna

2016-01-01

Benzene is a ubiquitous occupational and environmental pollutant. Improved industrial hygiene allowed airborne concentrations close to the environmental context (1-1000 µg/m(3)). Conversely, new limits for benzene levels in urban air were set (5 µg/m(3)). The biomonitoring of exposure to such low benzene concentrations are performed measuring specific and sensitive biomarkers such as S-phenylmercapturic acid, trans, trans-muconic acid and urinary benzene: many studies referred high variability in the levels of these biomarkers, suggesting the involvement of polymorphic metabolic genes in the individual susceptibility to benzene toxicity. We reviewed the influence of metabolic polymorphisms on the biomarkers levels of benzene exposure and effect, in order to understand the real impact of benzene exposure on subjects with increased susceptibility.

Law and regulation of benzene.

PubMed Central

Feitshans, I L

1989-01-01

OSHA has created final benzene regulations after extensive rulemakings on two occasions, 1978 and 1987. These standards have been the subject of extensive litigation for nearly 20 years. This article examines in detail the conceptual underpinnings of the Benzene Case, (which was decided by the U.S. Supreme Court in 1980) in light of U.S. administrative law precedents that have set limits upon administrative discretion under the test for "substantial evidence" and the "hard look doctrine." This article also addresses recent developments in the wake of the Benzene Case and their implications for benzene regulations following the "significant risk" doctrine in that case. This article briefly describes other national, regional, and international laws governing the use of benzene. This article concludes that the revisions of the benzene regulation and subsequent rulemaking provide substantial evidence of scientific underpinnings for regulatory action and that laws from other nations reflect an international consensus that occupational exposure to benzene is a proper subject of regulation. Such regulations and policies are therefore likely to withstand scrutiny and remain enforceable as widely accepted norms. PMID:2792048

Benzene patterns in different urban environments and a prediction model for benzene rates based on NOx values

NASA Astrophysics Data System (ADS)

Paz, Shlomit; Goldstein, Pavel; Kordova-Biezuner, Levana; Adler, Lea

2017-04-01

Exposure to benzene has been associated with multiple severe impacts on health. This notwithstanding, at most monitoring stations, benzene is not monitored on a regular basis. The aims of the study were to compare benzene rates in different urban environments (region with heavy traffic and industrial region), to analyse the relationship between benzene and meteorological parameters in a Mediterranean climate type, to estimate the linkages between benzene and NOx and to suggest a prediction model for benzene rates based on NOx levels in order contribute to a better estimation of benzene. Data were used from two different monitoring stations, located on the eastern Mediterranean coast: 1) a traffic monitoring station in Tel Aviv, Israel (TLV) located in an urban region with heavy traffic; 2) a general air quality monitoring station in Haifa Bay (HIB), located in Israel's main industrial region. At each station, hourly, daily, monthly, seasonal, and annual data of benzene, NOx, mean temperature, relative humidity, inversion level, and temperature gradient were analysed over three years: 2008, 2009, and 2010. A prediction model for benzene rates based on NOx levels (which are monitored regularly) was developed to contribute to a better estimation of benzene. The severity of benzene pollution was found to be considerably higher at the traffic monitoring station (TLV) than at the general air quality station (HIB), despite the location of the latter in an industrial area. Hourly, daily, monthly, seasonal, and annual patterns have been shown to coincide with anthropogenic activities (traffic), the day of the week, and atmospheric conditions. A strong correlation between NOx and benzene allowed the development of a prediction model for benzene rates, based on NOx, the day of the week, and the month. The model succeeded in predicting the benzene values throughout the year (except for September). The severity of benzene pollution was found to be considerably higher at the

Process for the preparation of ethyl benzene

DOEpatents

Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

1995-12-19

Ethyl benzene is produced in a catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 50 C to 300 C, using as the catalyst a mole sieve characterized as acidic by feeding ethylene to the catalyst bed while benzene is conveniently added through the reflux to result in a molar excess present in the reactor to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene and diethyl benzene in the bottoms. The bottoms are fractionated, the ethyl benzene recovered and the bottoms are contacted with benzene in the liquid phase in a fixed bed straight pass reactor under conditions to transalkylate the benzene thereby converting most of the diethyl benzene to ethyl benzene which is again separated and recovered. 2 figs.

Process for the preparation of ethyl benzene

DOEpatents

Smith, Jr., Lawrence A.; Arganbright, Robert P.; Hearn, Dennis

1995-01-01

Ethyl benzene is produced in a catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 50.degree. C. to 300.degree. C., using as the catalyst a mole sieve characterized as acidic by feeding ethylene to the catalyst bed while benzene is conveniently added through the reflux to result in a molar excess present in the reactor to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene and diethyl benzene in the bottoms. The bottoms are fractionated, the ethyl benzene recovered and the bottoms are contacted with benzene in the liquid phase in a fixed bed straight pass reactor under conditions to transalkylate the benzene thereby converting most of the diethyl benzene to ethyl benzene which is again separated and recovered.

Leukemia and Benzene

PubMed Central

Snyder, Robert

2012-01-01

Excessive exposure to benzene has been known for more than a century to damage the bone marrow resulting in decreases in the numbers of circulating blood cells, and ultimately, aplastic anemia. Of more recent vintage has been the appreciation that an alternative outcome of benzene exposure has been the development of one or more types of leukemia. While many investigators agree that the array of toxic metabolites, generated in the liver or in the bone marrow, can lead to traumatic bone marrow injury, the more subtle mechanisms leading to leukemia have yet to be critically dissected. This problem appears to have more general interest because of the recognition that so-called “second cancer” that results from prior treatment with alkylating agents to yield tumor remissions, often results in a type of leukemia reminiscent of benzene-induced leukemia. Furthermore, there is a growing literature attempting to characterize the fine structure of the marrow and the identification of so called “niches” that house a variety of stem cells and other types of cells. Some of these “niches” may harbor cells capable of initiating leukemias. The control of stem cell differentiation and proliferation via both inter- and intra-cellular signaling will ultimately determine the fate of these transformed stem cells. The ability of these cells to avoid checkpoints that would prevent them from contributing to the leukemogenic response is an additional area for study. Much of the study of benzene-induced bone marrow damage has concentrated on determining which of the benzene metabolites lead to leukemogenesis. The emphasis now should be directed to understanding how benzene metabolites alter bone marrow cell biology. PMID:23066403

Benzene oxidation at diamond electrodes: comparison of microcrystalline and nanocrystalline diamonds.

PubMed

Pleskov, Yu V; Krotova, M D; Elkin, V V; Varnin, V P; Teremetskaya, I G; Saveliev, A V; Ralchenko, V G

2012-08-27

A comparative study of benzene oxidation at boron-doped diamond (BDD) and nitrogenated nanocrystalline diamond (NCD) anodes in 0.5 M K(2)SO(4) aqueous solution is conducted by using cyclic voltammetry and electrochemical impedance spectroscopy. It is shown by measurements of differential capacitance and anodic current that during the benzene oxidation at the BDD electrode, adsorption of a reaction intermediate occurs, which partially blocks the electrode surface and lowers the anodic current. At the NCD electrode, benzene is oxidized concurrently with oxygen evolution, a (quinoid) intermediate being adsorbed at the electrode. The adsorption and the electrode surface blocking are reflected in the impedance-frequency and impedance-potential complex-plane plots. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oxidation of Naphthenoaromatic and Methyl-Substituted Aromatic Compounds by Naphthalene 1,2-Dioxygenase

PubMed Central

Selifonov, S. A.; Grifoll, M.; Eaton, R. W.; Chapman, P. J.

1996-01-01

Oxidation of acenaphthene, acenaphthylene, and fluorene was examined with recombinant strain Pseudomonas aeruginosa PAO1(pRE695) expressing naphthalene dioxygenase genes cloned from plasmid NAH7. Acenaphthene underwent monooxygenation to 1-acenaphthenol with subsequent conversion to 1-acenaphthenone and cis- and trans-acenaphthene-1,2-diols, while acenaphthylene was dioxygenated to give cis-acenaphthene-1,2-diol. Nonspecific dehydrogenase activities present in the host strain led to the conversion of both of the acenaphthene-1,2-diols to 1,2-acenaphthoquinone. The latter was oxidized spontaneously to naphthalene-1,8-dicarboxylic acid. No aromatic ring dioxygenation products were detected from acenaphthene and acenaphthylene. Mixed monooxygenase and dioxygenase actions of naphthalene dioxygenase on fluorene yielded products of benzylic 9-monooxygenation, aromatic ring dioxygenation, or both. The action of naphthalene dioxygenase on a variety of methyl-substituted aromatic compounds, including 1,2,4-trimethylbenzene and isomers of dimethylnaphthalene, resulted in the formation of benzylic alcohols, i.e., methyl group monooxygenation products, which were subsequently converted to the corresponding carboxylic acids by dehydrogenase(s) in the host strain. Benzylic monooxygenation of methyl groups was strongly predominant over aromatic ring dioxygenation and essentially nonspecific with respect to the substitution pattern of the aromatic substrates. In addition to monooxygenating benzylic methyl and methylene groups, naphthalene dioxygenase behaved as a sulfoxygenase, catalyzing monooxygenation of the sulfur heteroatom of 3-methylbenzothiophene. PMID:16535238

Anaerobic Benzene Oxidation by Geobacter Species

PubMed Central

Bain, Timothy S.; Nevin, Kelly P.; Barlett, Melissa A.; Lovley, Derek R.

2012-01-01

The abundance of Geobacter species in contaminated aquifers in which benzene is anaerobically degraded has led to the suggestion that some Geobacter species might be capable of anaerobic benzene degradation, but this has never been documented. A strain of Geobacter, designated strain Ben, was isolated from sediments from the Fe(III)-reducing zone of a petroleum-contaminated aquifer in which there was significant capacity for anaerobic benzene oxidation. Strain Ben grew in a medium with benzene as the sole electron donor and Fe(III) oxide as the sole electron acceptor. Furthermore, additional evaluation of Geobacter metallireducens demonstrated that it could also grow in benzene-Fe(III) medium. In both strain Ben and G. metallireducens the stoichiometry of benzene metabolism and Fe(III) reduction was consistent with the oxidation of benzene to carbon dioxide with Fe(III) serving as the sole electron acceptor. With benzene as the electron donor, and Fe(III) oxide (strain Ben) or Fe(III) citrate (G. metallireducens) as the electron acceptor, the cell yields of strain Ben and G. metallireducens were 3.2 × 109 and 8.4 × 109 cells/mmol of Fe(III) reduced, respectively. Strain Ben also oxidized benzene with anthraquinone-2,6-disulfonate (AQDS) as the sole electron acceptor with cell yields of 5.9 × 109 cells/mmol of AQDS reduced. Strain Ben serves as model organism for the study of anaerobic benzene metabolism in petroleum-contaminated aquifers, and G. metallireducens is the first anaerobic benzene-degrading organism that can be genetically manipulated. PMID:23001648

High Pressure Optical Studies of the Thallous Halides and of Charge-Transfer Complexes

NASA Astrophysics Data System (ADS)

Jurgensen, Charles Willard

High pressure was used to study the insulator -to-metal transition in sulfur and the thallous halides and to study the intermolecular interactions in charge -transfer complexes. The approach to the band overlap insulator -to-metal transition was studied in three thallous halides and sulfur by optical absorption measurements of the band gap as a function of pressure. The band gap of sulfur continuously decreases with pressure up to the insulator -to-metal transition which occurs between 450 and 485 kbars. The results on the thallous halides indicate that the indirect gap decreases more rapidly than the direct gap; the closing of the indirect gap is responsible for the observed insulator -to-metal transitions. High pressure electronic and vibrational spectroscopic measurements on the solid-state complexes of HMB-TCNE were used to study the intermolecular interactions of charge -transfer complexes. The vibrational frequency shifts indicate that the degree of charge transfer increases with pressure which is independently confirmed by an increase in the molar absorptivity of the electronic charge-transfer peak. Induction and dispersion forces contribute towards a red shift of the charge-transfer peak; however, charge-transfer resonance contributes toward a blue shift and this effect is dominant for the HMB-TCNE complexes. High pressure electronic spectra were used to study the effect of intermolecular interactions on the electronic states of TCNQ and its complexes. The red shifts with pressure of the electronic spectra of TCNQ and (TCNQ)(' -) in polymer media and of crystalline TCNQ can be understood in terms of Van der Waals interactions. None of the calculations which considered intradimer distance obtained the proper behavior for either the charge-transfer of the locally excited states of the complexes. The qualitative behavior of both states can be interpreted as the effect of increased mixing of the locally excited and charge transfer states.

Beyond the benzene dimer: an investigation of the additivity of pi-pi interactions.

PubMed

Tauer, Tony P; Sherrill, C David

2005-11-24

The benzene dimer is the simplest prototype of pi-pi interactions and has been used to understand the fundamental physics of these interactions as they are observed in more complex systems. In biological systems, however, aromatic rings are rarely found in isolated pairs; thus, it is important to understand whether aromatic pairs remain a good model of pi-pi interactions in clusters. In this study, ab initio methods are used to compute the binding energies of several benzene trimers and tetramers, most of them in 1D stacked configurations. The two-body terms change only slightly relative to the dimer, and except for the cyclic trimer, the three- and four-body terms are negligible. This indicates that aromatic clusters do not feature any large nonadditive effects in their binding energies, and polarization effects in benzene clusters do not greatly change the binding that would be anticipated from unperturbed benzene-benzene interactions, at least for the 1D stacked systems considered. Three-body effects are larger for the cyclic trimer, but for all systems considered, the computed binding energies are within 10% of what would be estimated from benzene dimer energies at the same geometries.

27 CFR 21.97 - Benzene.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Benzene. 21.97 Section 21... TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.97 Benzene. (a..., Standard No. D 836-77; for incorporation by reference, see § 21.6(b).) When 100 ml of benzene are distilled...

27 CFR 21.97 - Benzene.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Benzene. 21.97 Section 21... TREASURY ALCOHOL FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.97 Benzene. (a..., Standard No. D 836-77; for incorporation by reference, see § 21.6(b).) When 100 ml of benzene are distilled...

27 CFR 21.97 - Benzene.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Benzene. 21.97 Section 21... TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.97 Benzene. (a..., Standard No. D 836-77; for incorporation by reference, see § 21.6(b).) When 100 ml of benzene are distilled...

27 CFR 21.97 - Benzene.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Benzene. 21.97 Section 21... TREASURY ALCOHOL FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.97 Benzene. (a..., Standard No. D 836-77; for incorporation by reference, see § 21.6(b).) When 100 ml of benzene are distilled...

27 CFR 21.97 - Benzene.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Benzene. 21.97 Section 21... TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.97 Benzene. (a..., Standard No. D 836-77; for incorporation by reference, see § 21.6(b).) When 100 ml of benzene are distilled...

Band gaps and photocurrent responses of two novel alkaline earth metal(II) complexes based on 4,5-di(4‧-carboxylphenyl)benzene

NASA Astrophysics Data System (ADS)

Meng, Jiang Ping; Yan, Zhi Shuo; Long, Ji Ying; Gong, Yun; Lin, Jian Hua

2017-01-01

By using a rigid dicarboxylate ligand, 4,5-di(4‧-carboxylphenyl)benzene (H2L), two complexes formulated as SrL(DMF)(H2O)·(CH3CN) (DMF=N,N‧-dimethylformamide) (1) and BaL(H2O)2 (2) were solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complexes 1 and 2 display two-dimensional (2D) layer structures. The two complexes exhibit different electrochemical and photoelectrochemical properties. Their thermal stabilities, cyclic voltammograms, UV-vis absorption and diffuse reflectance spectra and photoluminescence properties have been investigated. The band structures, the total density of states (TDOS) and partial density of states (PDOS) of the two complexes were calculated by CASTEP program. Complex 2 exhibits much higher photocurrent density than complex 1. The Mott-Schottky plots reveal that complexes 1 and 2 both are p-type semiconductors, which are in agreement with their band structure calculations.

Metatranscriptome of an Anaerobic Benzene-Degrading, Nitrate-Reducing Enrichment Culture Reveals Involvement of Carboxylation in Benzene Ring Activation

PubMed Central

Luo, Fei; Gitiafroz, Roya; Devine, Cheryl E.; Gong, Yunchen; Hug, Laura A.; Raskin, Lutgarde

2014-01-01

The enzymes involved in the initial steps of anaerobic benzene catabolism are not known. To try to elucidate this critical step, a metatranscriptomic analysis was conducted to compare the genes transcribed during the metabolism of benzene and benzoate by an anaerobic benzene-degrading, nitrate-reducing enrichment culture. RNA was extracted from the mixed culture and sequenced without prior mRNA enrichment, allowing simultaneous examination of the active community composition and the differential gene expression between the two treatments. Ribosomal and mRNA sequences attributed to a member of the family Peptococcaceae from the order Clostridiales were essentially only detected in the benzene-amended culture samples, implicating this group in the initial catabolism of benzene. Genes similar to each of two subunits of a proposed benzene-carboxylating enzyme were transcribed when the culture was amended with benzene. Anaerobic benzoate degradation genes from strict anaerobes were transcribed only when the culture was amended with benzene. Genes for other benzoate catabolic enzymes and for nitrate respiration were transcribed in both samples, with those attributed to an Azoarcus species being most abundant. These findings indicate that the mineralization of benzene starts with its activation by a strict anaerobe belonging to the Peptococcaceae, involving a carboxylation step to form benzoate. These data confirm the previously hypothesized syntrophic association between a benzene-degrading Peptococcaceae strain and a benzoate-degrading denitrifying Azoarcus strain for the complete catabolism of benzene with nitrate as the terminal electron acceptor. PMID:24795366

Benzene destruction in aqueous waste—I. Bench-scale gamma irradiation experiments

NASA Astrophysics Data System (ADS)

Cooper, William J.; Dougal, Roger A.; Nickelsen, Michael G.; Waite, Thomas D.; Kurucz, Charles N.; Lin, Kaijin; Bibler, Jane P.

1996-07-01

Destruction of the benzene component of a simulated low-level mixed aqueous waste stream by high energy irradiation was explored. This work was motivated by the fact that mixed waste, containing both radionuclides and regulated (non-radioactive) chemicals, is more difficult and more expensive to dispose of than only radioactive waste. After the benzene is destroyed, the waste can then be listed only as radiological waste instead of mixed waste, simplifying its disposal. This study quantifies the removal of benzene, and the formation and destruction of reaction products in a relatively complex waste stream matrix consisting of NO 3-, SO 42-, PO 43-, Fe 2+ and detergent at a pH of 3. All of the experiments were conducted at a bench scale using a 60Co gamma source.

Particle-bound benzene from diesel engine exhaust.

PubMed

Muzyka, V; Veimer, S; Shmidt, N

1998-12-01

The large surface area of the carbon core of diesel exhaust particles may contribute to the adsorption or condensation of such volatile carcinogenic organic compounds as benzene. The attention of this study focused on determining the distribution of benzene between the gas and particulate phases in the breathing zone of bus garage workers. Benzene and suspended particulate matter were evaluated jointly in the air of a municipal bus garage. Personal passive monitors were used for benzene sampling in the breathing zone of the workers. Active samplers were used for sampling diesel exhaust particles and the benzene associated with them. The benzene levels were measured by gas chromatography. Diesel engine exhaust from buses was the main source of air pollution caused by benzene and particles in this study. The concentration of benzene in the gas and particulate phases showed a wide range of variation, depending on the distance of the workplace from the operating diesel engine. Benzene present in the breathing zone of the workers was distributed between the gas and particulate phases. The amounts of benzene associated with particles were significantly lower in summer than in winter. The particulate matter of diesel exhaust contains benzene in amounts comparable to the concentrations of carcinogenic polycyclic aromatic hydrocarbons (PAH) and the usually found nitro-PAH. The concentration of benzene in the gas phase and in the suspended particulate matter of air can serve as an additional indicator of exposure to diesel exhaust and its carcinogenicity.

An Improved Analysis of the Sevoflurane-Benzene Structure by Chirped Pulse Ftmw Spectroscopy

NASA Astrophysics Data System (ADS)

Seifert, Nathan A.; Perez, Cristobal; Zaleski, Daniel P.; Neill, Justin L.; Pate, Brooks H.; Lesarri, Alberto; Vallejo, Montserrat; Cocinero, Emilio J.; Castano, Fernando; Kleiner, Isabelle

2013-06-01

Recent improvements to the 2-8 GHz CP-FTMW spectrometer at University of Virginia have improved the structural and spectroscopic analysis of the sevoflurane-benzene cluster. Previously reported results, although robust, were limited to a fit of the a-type transitions of the normal species in the determination of the six-fold barrier to benzene internal rotation. Structural analysis was limited to the benzene hydrogen atom positions using benzene-d_{1}. The increased sensitivity of the new 2-8 GHz setup allows for a full internal rotation analysis of the a- and c-type transitions of the normal species, which was performed with BELGI. A fit value for V_{6} of 32.868(11) cm^{-1} is determined. Additionally, a full substitution structure of the benzene carbon atom positions was determined in natural abundance. Also, new measurements of a sevoflurane/benzene-d_{1} mixture enabled detection of 33 of the 60 possible ^{2}D / ^{13}C double isotopologues. This abundance of isotopic data, a total of 45 isotopologues, enabled a full heavy atom least-squares r_{0} structure fit for the complex, including positions for all seven fluorines in sevoflurane. N. A. Seifert, D. P. Zaleski, J. L. Neill, B. H. Pate, A. Lesarri, M. Vallejo, E. J. Cocinero, F. Castańo. 67th OSU Int. Symp. On Mol. Spectrosc., Columbus, OH, 2012, MH13.

Species differences in the metabolism of benzene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henderson, R.F.

1996-12-01

The pathways of metabolism of benzene appear to be qualitatively similar in all species studied thus far. However, there are quantitative differences in the fraction of benzene metabolized by the different pathways. These species differences become important for risk assessments based on animal data. Mice have a greater overall capacity to metabolize benzene than rats or primates, based on mass balance studies conducted in vivo using radiolabled benzene. Mice and monkeys metabolize more of the benzene to hydroquinone metabolites than do rats or chimpanzees, especially at low doses. Nonhuman primates metabolize less of the benzene to muconic acid than domore » rodents or humans. In all species studied, a greater proportion of benzene is converted to hydroquinone and ring-breakage metabolites at low doses than at high doses. This finding should be considered in attempting to extrapolate the toxicity of benzene observed at high doses to predicted toxicity at low doses. Because ring-breakage metabolites and hydroquinone have both been implicated in the toxicity of benzene, the higher formation of those metabolites in the mouse may partially explain why mice are more sensitive to benzene than are rats. Metabolism of benzene in humans, the species of interest, does not exactly mimic that of any animal species studied. More information on the urinary and blood metabolites of occupationally exposed people is required to determine the fractional conversion of benzene to putative toxic metabolites and the degree of variability present in human subjects. 12 refs., 4 tabs.« less

Anaerobic Benzene Oxidation via Phenol in Geobacter metallireducens

PubMed Central

Tremblay, Pier-Luc; Chaurasia, Akhilesh Kumar; Smith, Jessica A.; Bain, Timothy S.; Lovley, Derek R.

2013-01-01

Anaerobic activation of benzene is expected to represent a novel biochemistry of environmental significance. Therefore, benzene metabolism was investigated in Geobacter metallireducens, the only genetically tractable organism known to anaerobically degrade benzene. Trace amounts (<0.5 μM) of phenol accumulated in cultures of Geobacter metallireducens anaerobically oxidizing benzene to carbon dioxide with the reduction of Fe(III). Phenol was not detected in cell-free controls or in Fe(II)- and benzene-containing cultures of Geobacter sulfurreducens, a Geobacter species that cannot metabolize benzene. The phenol produced in G. metallireducens cultures was labeled with 18O during growth in H218O, as expected for anaerobic conversion of benzene to phenol. Analysis of whole-genome gene expression patterns indicated that genes for phenol metabolism were upregulated during growth on benzene but that genes for benzoate or toluene metabolism were not, further suggesting that phenol was an intermediate in benzene metabolism. Deletion of the genes for PpsA or PpcB, subunits of two enzymes specifically required for the metabolism of phenol, removed the capacity for benzene metabolism. These results demonstrate that benzene hydroxylation to phenol is an alternative to carboxylation for anaerobic benzene activation and suggest that this may be an important metabolic route for benzene removal in petroleum-contaminated groundwaters, in which Geobacter species are considered to play an important role in anaerobic benzene degradation. PMID:24096430

Concomitant aerobic biodegradation of benzene and thiophene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dyreborg, S.; Arvin, E.; Broholm, K.

The concomitant aerobic biodegradation of benzene and thiophene was investigated in microcosm experiments using a groundwater enrichment culture. Benzene was biodegraded within 1 d, whereas thiophene could not be biodegraded as the sole source of carbon and energy. Some interesting phenomena were observed when both benzene and thiophene were present. In most cases, removal of thiophene was observed, and the removal occurred concomitantly with the biodegradation of benzene, suggesting that benzene was used as a primary substrate in the cometabolic biodegradation of thiophene. No biodegradation of the two compounds was observed for some combinations of concentrations, suggesting that thiophene couldmore » act as an inhibitor to benzene biodegradation. However, this effect could be overcome if more benzene was added to the microcosm. Residual concentrations of benzene and thiophene were observed in some microcosms and the data indicated that the biodegradation of the two compounds stopped when a critical threshold ratio between the concentrations of thiophene and benzene was reached. This ratio varied between 10 and 20. Results from modeling the biodegradation data suggested that thiophene was cometabolized concomitantly with the biodegradation of benzene and that the biodegradation may be described by a modified model based on a traditional model with an inhibition term incorporated.« less

Benzene formation in electronic cigarettes.

PubMed

Pankow, James F; Kim, Kilsun; McWhirter, Kevin J; Luo, Wentai; Escobedo, Jorge O; Strongin, Robert M; Duell, Anna K; Peyton, David H

2017-01-01

The heating of the fluids used in electronic cigarettes ("e-cigarettes") used to create "vaping" aerosols is capable of causing a wide range of degradation reaction products. We investigated formation of benzene (an important human carcinogen) from e-cigarette fluids containing propylene glycol (PG), glycerol (GL), benzoic acid, the flavor chemical benzaldehyde, and nicotine. Three e-cigarette devices were used: the JUULTM "pod" system (provides no user accessible settings other than flavor cartridge choice), and two refill tank systems that allowed a range of user accessible power settings. Benzene in the e-cigarette aerosols was determined by gas chromatography/mass spectrometry. Benzene formation was ND (not detected) in the JUUL system. In the two tank systems benzene was found to form from propylene glycol (PG) and glycerol (GL), and from the additives benzoic acid and benzaldehyde, especially at high power settings. With 50:50 PG+GL, for tank device 1 at 6W and 13W, the formed benzene concentrations were 1.9 and 750 μg/m3. For tank device 2, at 6W and 25W, the formed concentrations were ND and 1.8 μg/m3. With benzoic acid and benzaldehyde at ~10 mg/mL, for tank device 1, values at 13W were as high as 5000 μg/m3. For tank device 2 at 25W, all values were ≤~100 μg/m3. These values may be compared with what can be expected in a conventional (tobacco) cigarette, namely 200,000 μg/m3. Thus, the risks from benzene will be lower from e-cigarettes than from conventional cigarettes. However, ambient benzene air concentrations in the U.S. have typically been 1 μg/m3, so that benzene has been named the largest single known cancer-risk air toxic in the U.S. For non-smokers, chronically repeated exposure to benzene from e-cigarettes at levels such as 100 or higher μg/m3 will not be of negligible risk.

Is benzene exposure from gasoline carcinogenic?

PubMed

Jamall, Ijaz S; Willhite, Calvin C

2008-02-01

This article questions the basis for benzene as the carcinogenic surrogate in deriving health risk-based 'clean-up levels' for gasoline-impacted soil and groundwater at leaking underground storage tank properties. The epidemiological evidence suggests that acute myelogenous leukemia (AML) associated with chronic occupational benzene exposure can be best described by sigmoid dose-response relationships. A review of the molecular toxicology and kinetics of benzene points to the existence of threshold mechanisms in the induction of leukemia. The toxicological and epidemiological literature on chronic exposure to unleaded gasoline indicates that the benzene exposures required to induce a measurable carcinogenic response are substantially greater than exposures likely to be encountered from exposure to gasoline at contaminated properties. Thus, assuming that theoretical cancer risks associated with exposure to benzene from gasoline reflect actual health risks associated with such environmental exposures to gasoline and using these theoretical cancer risks and cancer potency factors for benzene to dictate soil and groundwater clean up of gasoline are not scientifically defensible.

OPHIDIAN L-AMINO ACID OXIDASE. THE NATURE OF THE ENZYME-SUBSTRATE COMPLEXES.

PubMed

ZELLER, E A; RAMACHANDER, G; FLEISHER, G A; ISHIMARU, T; ZELLER, V

1965-04-01

1. To investigate the kinetics of ophidian l-amino acid oxidase, V and K(m) were determined for phenylalanines that were substituted in every ring position with groups of various size and reactivity, and for a few ring-substituted tryptophans and histidines. The venom of one representative from each of three major classes of poisonous snakes, Naja melanoleuca, Vipera russelli and Crotalus adamanteus, served as a source of the ophidian l-amino acid oxidase. Both crude and crystalline enzyme from the venom of C. adamanteus were tested. 2. The introduction of a benzene ring into glycine and alanine caused some increase of V and a very marked depression of K(m). 3. With the exception of fluorine, residues in the ortho position of phenylalanine led to a decrease of V. The rates induced by various substitutions follow the pattern: meta >/= para >/= ortho. Within the halogen series, the effects become more pronounced with increasing atomic number. 4. Ring substitution in heterocyclic amino acids also affected the V values markedly. For methyl-substituted tryptophans the pattern was: 5-methyl >/= 6-methyl >/= 4-methyl. In a few instances ring substitution accounts for a considerable elevation of V, as shown for beta-quinol-4-ylalanine and its 6-methoxy derivative. 5. The kinetic constants appear to be unaffected by relatively high concentrations of the corresponding d-amino acids. 6. A general principle that permits a uniform interpretation of a vast body of information is suggested. It is based on the assumption that most substrates form not only eutopic but also dystopic complexes with the enzyme. The latter, in contrast with the former, do not permit the formation of reaction products. K values for eutopic and dystopic complexes are computed. Similar concepts have been presented to elucidate the action of alpha-chymotrypsin (Hein & Niemann, 1962) and of monoamine oxidase.

Anaerobic degradation of benzene in diverse anoxic environments

USGS Publications Warehouse

Kazumi, J.; Caldwell, M.E.; Suflita, J.M.; Lovely, D.R.; Young, L.Y.

1997-01-01

Benzene has often been observed to be resistant to microbial degradation under anoxic conditions. A number of recent studies, however, have demonstrated that anaerobic benzene utilization can occur. This study extends the previous reports of anaerobic benzene degradation to sediments that varied with respect to contamination input, predominant redox condition, and salinity. In spite of differences in methodology, microbial degradation of benzene was noted in slurries constructed with sediments from various geographical locations and range from aquifer sands to fine-grained estuarine muds, under methanogenic, sulfate-reducing, and iron-reducing conditions. In aquifer sediments under methanogenic conditions, benzene loss was concomitant with methane production, and microbial utilization of [14C]benzene yielded 14CO2 and 14CH4. In slurries with estuarine and aquifer sediments under sulfate-reducing conditions, the loss of sulfate in amounts consistent with the stoichiometric degradation of benzene or the conversion of [14C]benzene to 14CO2 indicates that benzene was mineralized. Benzene loss also occurred in the presence of Fe(III) in sediments from freshwater environments. Microbial benzene utilization, however, was not observed under denitrifying conditions. These results indicate that the potential for the anaerobic degradation of benzene, which was once thought to be resistant to non-oxygenase attack, exists in a variety of aquatic sediments from widely distributed locations.

(Z)-3-Methyl-4-[1-(4-methyl­anilino)propyl­idene]-1-phenyl-1H-pyrazol-5(4H)-one

PubMed Central

Sharma, Naresh; Vyas, Komal M.; Jadeja, R. N.; Kant, Rajni; Gupta, Vivek K.

2013-01-01

In the title mol­ecule, C20H21N3O, the central pyrazole ring forms dihedral angles of 4.75 (9) and 49.11 (9)°, respectively, with the phenyl and methyl-substituted benzene rings. The dihedral angle between the phenyl and benzene rings is 51.76 (8)°. The amino group and carbonyl O atom are involved in an intra­molecular N—H⋯O hydrogen bond. In the crystal, π–π inter­actions are observed between benzene rings [centroid–centroid seperation = 3.892 (2) Å] and pyrazole rings [centroid–centroid seperation = 3.626 (2) Å], forming chains along [111]. The H atoms of the methyl group on the p-tolyl substituent were refined as disordered over two sets of sites in a 0.60 (4):0.40 (4) ratio. PMID:24109353

Mechanistic considerations in benzene physiological model development.

PubMed

Medinsky, M A; Kenyon, E M; Seaton, M J; Schlosser, P M

1996-12-01

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene in humans are well documented and include aplastic anemia, pancytopenia, and acute myelogenous leukemia. However, the risks of leukemia at low exposure concentrations have not been established. A combination of metabolites (hydroquinone and phenol, for example) may be necessary to duplicate the hematotoxic effect of benzene, perhaps due in part to the synergistic effect of phenol on myeloperoxidase-mediated oxidation of hydroquinone to the reactive metabolite benzoquinone. Because benzene and its hydroxylated metabolites (phenol, hydroquinone, and catechol) are substrates for the same cytochrome P450 enzymes, competitive interactions among the metabolites are possible. In vivo data on metabolite formation by mice exposed to various benzene concentrations are consistent with competitive inhibition of phenol oxidation by benzene. In vitro studies of the metabolic oxidation of benzene, phenol, and hydroquinone are consistent with the mechanism of competitive interaction among the metabolites. The dosimetry of benzene and its metabolites in the target tissue, bone marrow, depends on the balance of activation processes such as enzymatic oxidation and deactivation processes such as conjugation and excretion. Phenol, the primary benzene metabolite, can undergo both oxidation and conjugation. Thus the potential exists for competition among various enzymes for phenol. Zonal localization of phase I and phase II enzymes in various regions of the liver acinus also impacts this competition. Biologically based dosimetry models that incorporate the important determinants of benzene flux, including interactions with other chemicals, will enable prediction of target tissue doses of benzene and metabolites at low exposure concentrations relevant for humans.

The separation distance distribution in electron-donor-acceptor systems and the wavelength dependence of free ion yields

NASA Astrophysics Data System (ADS)

Zhou, Jinwei; Findley, Bret R.; Braun, Charles L.; Sutin, Norman

2001-06-01

We recently reported that free radical ion quantum yields for electron-donor-acceptor (EDA) systems of alkylbenzenes-tetracyanoethylene (TCNE) exhibit a remarkable wavelength dependence in dichloromethane, a medium polarity solvent. We proposed that weak absorption by long-distance, unassociated or "random" D⋯A pairs is mainly responsible for the free radical ion yield. Here a model for the wavelength dependence of the free ion yield is developed for four systems in which differing degrees of EDA complex formation are present: 1,3,5-tri-tert-butylbenzene-TCNE in which only random pairs exist due to the bulky groups on the electron donor, and toluene—TCNE, 1,3,5-triethylbenzene-TCNE and 1,3,5-trimethylbenzene-TCNE. Mulliken-Hush theory is used to determine the excitation distance distribution of unassociated, random pairs at different wavelengths. For each absorption distribution, free radical ion yields at different wavelengths are then calculated using Onsager's result for the ion separation probability. Encouraging agreement between the calculated yields and our experimental results is obtained. As far as we are aware, this is the first time that photoexcitation of unassociated donor/acceptor pairs has been invoked as the source of separated radical ion pairs.

Elevated Atmospheric Levels of Benzene and Benzene-Related Compounds from Unconventional Shale Extraction and Processing: Human Health Concern for Residential Communities.

PubMed

Rich, Alisa L; Orimoloye, Helen T

2016-01-01

The advancement of natural gas (NG) extraction across the United States (U.S.) raises concern for potential exposure to hazardous air pollutants (HAPs). Benzene, a HAP and a primary chemical of concern due to its classification as a known human carcinogen, is present in petroleum-rich geologic formations and is formed during the combustion of bypass NG. It is a component in solvents, paraffin breakers, and fuels used in NG extraction and processing (E&P). The objectives of this study are to confirm the presence of benzene and benzene-related compounds (benzene[s]) in residential areas, where unconventional shale E&P is occurring, and to determine if benzene[s] exists in elevated atmospheric concentrations when compared to national background levels. Ambient air sampling was conducted in six counties in the Dallas/Fort Worth Metroplex with passive samples collected in evacuated 6-L Summa canisters. Samples were analyzed by gas chromatography/mass spectrometry, with sampling performed at variable distances from the facility fence line. Elevated concentrations of benzene[s] in the atmosphere were identified when compared to U.S. Environmental Protection Agency's Urban Air Toxics Monitoring Program. The 24-hour benzene concentrations ranged from 0.6 parts per billion by volume (ppbv) to 592 ppbv, with 1-hour concentrations from 2.94 ppbv to 2,900.20 ppbv. Benzene is a known human carcinogen capable of multisystem health effects. Exposure to benzene is correlated with bone marrow and blood-forming organ damage and immune system depression. Sensitive populations (children, pregnant women, elderly, immunocompromised) and occupational workers are at increased risk for adverse health effects from elevated atmospheric levels of benzene[s] in residential areas with unconventional shale E&P.

46 CFR 30.25-3 - Benzene.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 1 2013-10-01 2013-10-01 false Benzene. 30.25-3 Section 30.25-3 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Commodities Regulated § 30.25-3 Benzene. The provisions contained in 46 CFR part 197, subpart C, apply to liquid cargoes containing 0.5% or more benzene...

46 CFR 30.25-3 - Benzene.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 1 2011-10-01 2011-10-01 false Benzene. 30.25-3 Section 30.25-3 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Commodities Regulated § 30.25-3 Benzene. The provisions contained in 46 CFR part 197, subpart C, apply to liquid cargoes containing 0.5% or more benzene...

46 CFR 30.25-3 - Benzene.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Benzene. 30.25-3 Section 30.25-3 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Commodities Regulated § 30.25-3 Benzene. The provisions contained in 46 CFR part 197, subpart C, apply to liquid cargoes containing 0.5% or more benzene...

46 CFR 30.25-3 - Benzene.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 1 2012-10-01 2012-10-01 false Benzene. 30.25-3 Section 30.25-3 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Commodities Regulated § 30.25-3 Benzene. The provisions contained in 46 CFR part 197, subpart C, apply to liquid cargoes containing 0.5% or more benzene...

46 CFR 30.25-3 - Benzene.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 1 2014-10-01 2014-10-01 false Benzene. 30.25-3 Section 30.25-3 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Commodities Regulated § 30.25-3 Benzene. The provisions contained in 46 CFR part 197, subpart C, apply to liquid cargoes containing 0.5% or more benzene...

54 FR 38044: National Emission Standards for Hazardous Air Pollutants; Benzene Emissions From Maleic Anhydride Plants, Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and Coke By- Product Recovery Plants

EPA Pesticide Factsheets

Final Rule on National Emission Standards for Hazardous Air Pollutants; Benzene Emissions From Maleic Anhydride Plants, Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and Coke By-Product Recovery Plants.

The influence of different light quality and benzene on gene expression and benzene degradation of Chlorophytum comosum.

PubMed

Setsungnern, Arnon; Treesubsuntorn, Chairat; Thiravetyan, Paitip

2017-11-01

Benzene, a carcinogenic compound, has been reported as a major indoor air pollutant. Chlorophytum comosum (C. comosum) was reported to be the highest efficient benzene removal plant among other screened plants. Our previous studies found that plants under light conditions could remove gaseous benzene higher than under dark conditions. Therefore, C. comosum exposure to airborne benzene was studied under different light quality at the same light intensity. C. comosum could remove 500 ppm gaseous benzene with the highest efficiency of 68.77% under Blue:Red = 1:1 LED treatments and the lowest one appeared 57.41% under white fluorescent treatment within 8 days. After benzene was uptaken by C. comosum, benzene was oxidized to be phenol in the plant cells by cytochrome P450 monooxygenase system. Then, phenol was catalyzed to be catechol that was confirmed by the up-regulation of phenol 2-monooxygenase (PMO) gene expression. After that, catechol was changed to cic, cis-muconic acid. Interestingly, cis,cis-muconic acid production was found in the plant tissues higher than phenol and catechol. The result confirmed that NADPH-cytochrome P450 reductase (CPR), cytochrome b5 (cyt b5), phenol 2-monooxygenase (PMO) and cytochrome P450 90B1 (CYP90B1) in plant cells were involved in benzene degradation or detoxification. In addition, phenol, catechol, and cis,cis-muconic acid production were found under the Blue-Red LED light conditions higher than under white fluorescent light conditions due to under LED light conditions gave higher NADPH contents. Hence, C. comosum under the Blue-Red LED light conditions had a high potential to remove benzene in a contaminated site. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Irradiated Benzene Ice Provides Clues to Meteoritic Organic Chemistry

NASA Technical Reports Server (NTRS)

Callahan, Michael Patrick; Gerakines, Perry Alexander; Martin, Mildred G.; Hudson, Reggie L.; Peeters, Zan

2013-01-01

Aromatic hydrocarbons account for a significant portion of the organic matter in carbonaceous chondrite meteorites, as a component of both the low molecular weight, solvent-extractable compounds and the insoluble organic macromolecular material. Previous work has suggested that the aromatic compounds in carbonaceous chondrites may have originated in the radiation-processed icy mantles of interstellar dust grains. Here we report new studies of the organic residue made from benzene irradiated at 19 K by 0.8 MeV protons. Polyphenyls with up to four rings were unambiguously identified in the residue by gas chromatography-mass spectrometry. Atmospheric pressure photoionization Fourier transform mass spectrometry was used to determine molecular composition, and accurate mass measurements suggested the presence of polyphenyls, partially hydrogenated polyphenyls, and other complex aromatic compounds. The profile of low molecular weight compounds in the residue compared well with extracts from the Murchison and Orgueil meteorites. These results are consistent with the possibility that solid phase radiation chemistry of benzene produced some of the complex aromatics found in meteorites.

Refiners have several options for reducing gasoline benzene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goelzer, A.R.; Hernandez-Robinson, A.; Ram, S.

1993-09-13

Although the linkage between gasoline benzene content and evaporative, running, and tailpipe emission is not yet defined, the U.S. 1990 Clean Air Act Amendments mandate a benzene content of less than 1.0 vol% in reformulated gasolines. Likewise, the California Air Resources Board plans to restrict benzene to less than about 0.8 vol %. Mobil Research and Development Corp. and Badger Co. Inc. have developed several alternatives for reducing benzene levels in gasoline. Where benzene extraction is viable and maximum catalytic reformer hydrogen is needed, the companies' cumene and ethylbenzene processes are desirable. Mobil's benzene reduction process can be an alternativemore » to benzene hydrosaturation. All of these processes utilize low-value offgas from the fluid catalytic cracking (FCC) unit.« less

Benzene

Integrated Risk Information System (IRIS)

EPA / 635 / R - 02 / 001F TOXICOLOGICAL REVIEW OF BENZENE ( NONCANCER EFFECTS ) ( CAS No . 71 - 43 - 2 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) October 2002 U.S . Environmental Protection Agency Washington , DC DISCLAIMER This document has been

Non-parametric estimation of low-concentration benzene metabolism.

PubMed

Cox, Louis A; Schnatter, A Robert; Boogaard, Peter J; Banton, Marcy; Ketelslegers, Hans B

2017-12-25

Two apparently contradictory findings in the literature on low-dose human metabolism of benzene are as follows. First, metabolism is approximately linear at low concentrations, e.g., below 10 ppm. This is consistent with decades of quantitative modeling of benzene pharmacokinetics and dose-dependent metabolism. Second, measured benzene exposure and metabolite concentrations for occupationally exposed benzene workers in Tianjin, China show that dose-specific metabolism (DSM) ratios of metabolite concentrations per ppm of benzene in air decrease steadily with benzene concentration, with the steepest decreases below 3 ppm. This has been interpreted as indicating that metabolism at low concentrations of benzene is highly nonlinear. We reexamine the data using non-parametric methods. Our main conclusion is that both findings are correct; they are not contradictory. Low-concentration metabolism can be linear, with metabolite concentrations proportional to benzene concentrations in air, and yet DSM ratios can still decrease with benzene concentrations. This is because a ratio of random variables can be negatively correlated with its own denominator even if the mean of the numerator is proportional to the denominator. Interpreting DSM ratios that decrease with air benzene concentrations as evidence of nonlinear metabolism is therefore unwarranted when plots of metabolite concentrations against benzene ppm in air show approximately straight-line relationships between them, as in the Tianjin data. Thus, an apparent contradiction that has fueled heated discussions in the recent literature can be resolved by recognizing that highly nonlinear, decreasing DSM ratios are consistent with linear metabolism. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Mobil-Badger technologies for benzene reduction in gasoline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goelzer, A.R.; Ram, S.; Hernandez, A.

1993-01-01

Many refiners will need to reduce the barrels per day of benzene entering the motor gasoline pool. Mobil and Badger have developed and now jointly license three potential refinery alternatives to conventional benzene hydrosaturation to achieve this: Mobil Benzene Reduction, Ethylbenzene and Cumene. The Mobil Benzene Reduction Process (MBR) uses dilute olefins in FCC offgas to extensively alkylate dilute benzene as found in light reformate, light FCC gasoline, or cyclic C[sub 6] naphtha. MBR raises octanes and lowers C[sub 5]+ olefins. MBR does not involve costly hydrogen addition. The refinery-based Mobil/Badger Ethylbenzene Process reacts chemical-grade benzene extracted from light reformatemore » with dilute ethylene found in treated FCC offgas to make high-purity ethylbenzene. EB is the principal feedstock for the production of styrene. The Mobil/Badger Cumene Process alkylates FCC-derived dilute propylene and extracted benzene to selectively yield isopropyl benzene (cumene). Cumene is the principal feedstock for the production of phenol. All three processes use Mobil developed catalysts.« less

Cytokine Network Involvement in Subjects Exposed to Benzene

PubMed Central

Gangemi, Sebastiano

2014-01-01

Benzene represents an ubiquitous pollutant both in the workplace and in the general environment. Health risk and stress posed by benzene have long been a concern because of the carcinogenic effects of the compound which was classified as a Group 1 carcinogen to humans and animals. There is a close correlation between leukemia, especially acute myeloid leukemia, and benzene exposure. In addition, exposure to benzene can cause harmful effects on immunological, neurological, and reproductive systems. Benzene can directly damage hematopoietic progenitor cells, which in turn could lead to apoptosis or may decrease responsiveness to cytokines and cellular adhesion molecules. Alternatively, benzene toxicity to stromal cells or mature blood cells could disrupt the regulation of hematopoiesis, including hematopoietic commitment, maturation, or mobilization, through the network of cytokines, chemokines, and adhesion molecules. Today there is mounting evidence that benzene may alter the gene expression, production, or processing of several cytokines in vitro and in vivo. The purpose of this review was to systematically analyze the published cases of cytokine effects on human benzene exposure, particularly hematotoxicity, and atopy, and on lungs. PMID:25202711

Oxidation Mechanisms of Toluene and Benzene

NASA Technical Reports Server (NTRS)

Bittker, David A.

1995-01-01

An expanded and improved version of a previously published benzene oxidation mechanism is presented and shown to model published experimental data fairly successfully. This benzene submodel is coupled to a modified version of a toluene oxidation submodel from the recent literature. This complete mechanism is shown to successfully model published experimental toluene oxidation data for a highly mixed flow reactor and for higher temperature ignition delay times in a shock tube. A comprehensive sensitivity analysis showing the most important reactions is presented for both the benzene and toluene reacting systems. The NASA Lewis toluene mechanism's modeling capability is found to be equivalent to that of the previously published mechanism which contains a somewhat different benzene submodel.

29 CFR 1915.1028 - Benzene.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 7 2010-07-01 2010-07-01 false Benzene. 1915.1028 Section 1915.1028 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Benzene. Note: The requirements applicable to shipyard employment under this section are identical to...

29 CFR 1915.1028 - Benzene.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 29 Labor 7 2014-07-01 2014-07-01 false Benzene. 1915.1028 Section 1915.1028 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Benzene. Note: The requirements applicable to shipyard employment under this section are identical to...

29 CFR 1915.1028 - Benzene.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 29 Labor 7 2013-07-01 2013-07-01 false Benzene. 1915.1028 Section 1915.1028 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Benzene. Note: The requirements applicable to shipyard employment under this section are identical to...

29 CFR 1915.1028 - Benzene.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 7 2011-07-01 2011-07-01 false Benzene. 1915.1028 Section 1915.1028 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Benzene. Note: The requirements applicable to shipyard employment under this section are identical to...

29 CFR 1915.1028 - Benzene.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 29 Labor 7 2012-07-01 2012-07-01 false Benzene. 1915.1028 Section 1915.1028 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Benzene. Note: The requirements applicable to shipyard employment under this section are identical to...

Competitive Nitration of Benzene-Fluorobenzene and Benzene-Toluene Mixtures: Orientation and Reactivity Studies Using HPLC

ERIC Educational Resources Information Center

Blankespoor, Ronald L.; Hogendoorn, Stephanie; Pearson, Andrea

2007-01-01

The reactivity and orientation effects of a substituent are analyzed by using HPLC to determine the competitive nitration of the benzene-toluene and benzene-fluorobenzene mixtures. The results have shown that HPLC is an excellent instrumental method to use in analyzing these mixtures.

A comprehensive study of benzene concentrations and emissions in Houston

NASA Astrophysics Data System (ADS)

Müller, Markus; Eichler, Philipp; Berk Knighton, W.; Estes, Mark; Crawford, James H.; Mikoviny, Tomas; Wisthaler, Armin

2014-05-01

The Houston Metropolitan Area (Greater Houston) has a population of over 6 million people, it ranks among the three fastest growing metropolises in the developed world and population growth scenarios predict it to reach megacity status in the coming two to four decades. Greater Houston is home to the largest petrochemical-manufacturing complex in the world with important consequences for the environment in the region. Direct and fugitive emissions of hydrocarbons adversely affect Houston's air quality which has been subject to intense studies over the past two decades. In 2013, NASA conducted the DISCOVER-AQ field campaign in support of developing a satellite-based capability to assess Houston's air quality in the future. Amongst other measurements, airborne, mobile ground-based and stationary ground-based measurements of benzene were carried out. Benzene is a carcinogenic air toxic with strict exposure regulations in the U.S. and in Europe. We have used the obtained comprehensive dataset to map benzene concentrations in the Houston metropolitan area, locate and identify point sources, compare industrial and traffic emissions and put them in relation to previous measurements and emission inventories. The obtained data will allow a better assessment of health risks associated with benzene exposure in a large metropolitan area that includes both traffic and industrial benzene sources. This work was funded by BMVIT / FFG-ALR in the frame of the Austrian Space Application Programme (ASAP 8, project 833451). PE was funded through the PIMMS ITN (EU-FP7, agreement number 287382). Additional resources were provided through NASA's Earth Venture program (EV-1) and the NASA Postdoctoral Program (NPP). We want to thank Scott Herndon and Aerodyne Research for their support.

Mechanism of Benzene Tribopolymerization on the RuO2 (110) Surface

NASA Astrophysics Data System (ADS)

Yang, J.; Qi, Y.; Kim, H. D.; Rappe, A. M.

2018-04-01

A tribopolymer formed on the contacts of microelectromechanical and nanoelectromechanical system (MEMS-NEMS) devices is a major concern hampering their practical use in information technology. Conductive metal oxides, such as RuO2 and ReO3 , have been regarded as promising candidate materials for MEMS-NEMS contacts due to their conductivity, hardness, and relatively chemically inert surfaces. However, recent experimental works demonstrate that trace amounts of a polymer could still form on RuO2 surfaces. We demonstrate the mechanism of this class of unexpected tribopolymer formation by conducting density-functional-theory-based computational compression experiments with benzene as the contamination gas. First, mechanical force during compression changes the benzene molecules from slightly physisorbed to strongly chemisorbed. Further compression causes deformation and chemical linkage of the benzene molecules. Finally, the two contacts detach, with one having a complex organic molecule attached and the other a more reactive surface. The complex organic molecule, which has an oxabicyclic segment, can be viewed as the rudiment of a tribopolymer, and the more reactive surface can trigger the next adsorption-reaction-tribopolymer formation cycle. Based on these results, we also predict tribopolymer formation rates by using transition-state theory and the second-order rate law. We promote a deeper understanding of tribopolymer formation (especially on metal oxides) and provide strategies for suppressing tribopolymerization.

40 CFR 721.1187 - Bis(imidoethylene) benzene.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Bis(imidoethylene) benzene. 721.1187... Substances § 721.1187 Bis(imidoethylene) benzene. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance bis(imidoethylene)benzene (PMN P-93-1447) is subject to reporting...

40 CFR 721.1187 - Bis(imidoethylene) benzene.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Bis(imidoethylene) benzene. 721.1187... Substances § 721.1187 Bis(imidoethylene) benzene. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance bis(imidoethylene)benzene (PMN P-93-1447) is subject to reporting...

40 CFR 721.1187 - Bis(imidoethylene) benzene.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Bis(imidoethylene) benzene. 721.1187... Substances § 721.1187 Bis(imidoethylene) benzene. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance bis(imidoethylene)benzene (PMN P-93-1447) is subject to reporting...

40 CFR 721.1187 - Bis(imidoethylene) benzene.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Bis(imidoethylene) benzene. 721.1187... Substances § 721.1187 Bis(imidoethylene) benzene. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance bis(imidoethylene)benzene (PMN P-93-1447) is subject to reporting...

40 CFR 721.1187 - Bis(imidoethylene) benzene.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Bis(imidoethylene) benzene. 721.1187... Substances § 721.1187 Bis(imidoethylene) benzene. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance bis(imidoethylene)benzene (PMN P-93-1447) is subject to reporting...

Current collapse in tunneling transport through benzene.

PubMed

Hettler, M H; Wenzel, W; Wegewijs, M R; Schoeller, H

2003-02-21

We investigate the electrical transport through a system of benzene coupled to metal electrodes by electron tunneling. Using electronic structure calculations, a semiquantitative model for the pi electrons of the benzene is derived that includes general two-body interactions. After exact diagonalization of the benzene model the transport is computed using perturbation theory for weak electrode-benzene coupling (golden rule approximation). We include the effect of an applied electric field on the molecular states, as well as radiative relaxation. We predict a current collapse and strong negative differential conductance due to a "blocking" state when the electrode is coupled to the para-position of benzene. In contrast, for coupling to the meta-position, a series of steps in the I-V curve is found.

29 CFR 1926.1128 - Benzene.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 8 2011-07-01 2011-07-01 false Benzene. 1926.1128 Section 1926.1128 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1128 Benzene. Note...

46 CFR 153.1060 - Benzene.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Benzene. 153.1060 Section 153.1060 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1060 Benzene...

29 CFR 1926.1128 - Benzene.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 29 Labor 8 2014-07-01 2014-07-01 false Benzene. 1926.1128 Section 1926.1128 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1128 Benzene. Note...

46 CFR 153.1060 - Benzene.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Benzene. 153.1060 Section 153.1060 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1060 Benzene...

29 CFR 1926.1128 - Benzene.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 29 Labor 8 2012-07-01 2012-07-01 false Benzene. 1926.1128 Section 1926.1128 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1128 Benzene. Note...

29 CFR 1926.1128 - Benzene.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 8 2010-07-01 2010-07-01 false Benzene. 1926.1128 Section 1926.1128 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1128 Benzene. Note...

29 CFR 1926.1128 - Benzene.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 29 Labor 8 2013-07-01 2013-07-01 false Benzene. 1926.1128 Section 1926.1128 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1128 Benzene. Note...

46 CFR 153.1060 - Benzene.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Benzene. 153.1060 Section 153.1060 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1060 Benzene...

46 CFR 153.1060 - Benzene.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Benzene. 153.1060 Section 153.1060 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1060 Benzene...

46 CFR 153.1060 - Benzene.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Benzene. 153.1060 Section 153.1060 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1060 Benzene...

Cation Dependence of the Dimerization Enthalpy for A2 [tetracyanoethylene]2 (A=NMe4 , Mepy, NEt4 ) Possessing a Long, Multicenter Bond.

PubMed

Graham, Adora G; Fedin, Matvey V; Miller, Joel S

2017-09-12

[TCNE] .- (TCNE=tetracyanoethylene) has been isolated as D 2h π-[TCNE] 2 2- possessing a long, 2.9 Å multicenter 2-electron-4-center (2e - /4c) C-C bond, and as C 2 π-[TCNE] 2 2- possessing a longer, 3.04 Å multicenter 2e - /6c (4 C+2 N atoms) bond. Temperature-dependent UV/Vis spectroscopic measurements in 2-methyltetrahydrofuran (MeTHF) has led to the determination of the dimerization, 2[TCNE] .- ⇌π-[TCNE] 2 2- , equilibrium constants, K eq (T), [[TCNE] 2 2- ]/[[TCNE] .- ] 2 , enthalpy, ΔH, and entropy, ΔS, of dimerization for [Mepy] 2 [TCNE] 2 (Mepy=N-methylpyridinium, H 3 CNC 5 H 5 + ) possessing D 2h π-[TCNE] 2 2- and [NMe 4 ] 2 [TCNE] 2 possessing C 2 π-[TCNE] 2 2- conformations in the solid state; however, both form D 2h π-[TCNE] 2 2- in MeTHF solution. Based on ΔH=-3.6±0.1 kcal mol -1 (-15.2 kJ mol -1 ), and ΔS=-11±1 eu (-47 J mol -1  K -1 ) and ΔH=-2.4±0.2 kcal mol -1 (-10.2 kJ mol -1 ), and ΔS=-8±1 eu (-32 J mol -1  K -1 ) in MeTHF for [NMe 4 ] 2 [TCNE] 2 and [Mepy] 2 [TCNE] 2 , respectively, the calculated K eq (298 K) are 1.6 and 1.3 m -1 , respectively. The observed K eq (145 K) are 3 and 2 orders of magnitude greater for [NMe 4 ] 2 [TCNE] 2 and [Mepy] 2 [TCNE] 2 , respectively. The K eq (130 K) is 4470, 257, ≈0.8, and ≪0.1 m -1 for [NMe 4 ] 2 [TCNE] 2 , [Mepy] 2 [TCNE] 2 , [NEt 4 ] 2 [TCNE] 2 , and [N(nBu) 4 ] 2 [TCNE] 2 , respectively, decreasing with increasing cation size. At standard conditions and below ambient temperature the equilibrium favors the dimer for the NMe 4 + and Mepy + cations. From the decreasing enthalpy, NMe 4 + >Mepy + , along with the decrease in dimer formation K eq (T) as NMe 4 + >Mepy + >NEt 4 + >N(nBu) 4 + , the dimer bond energy decreases with increasing cation size in MeTHF. This is attributed to a decrease in the [A] + ⋅⋅⋅[TCNE] - attractive interactions with increasing cation size. Solid state UV/Vis spectroscopic determinations of [NMe 4 ] 2

40 CFR 721.1210 - Benzene, (2-chloroethoxy)-.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzene, (2-chloroethoxy)-. 721.1210... Substances § 721.1210 Benzene, (2-chloroethoxy)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (2-chloroethoxy)- (PMN P-87-1471) is subject to...

40 CFR 721.1210 - Benzene, (2-chloroethoxy)-.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, (2-chloroethoxy)-. 721.1210... Substances § 721.1210 Benzene, (2-chloroethoxy)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (2-chloroethoxy)- (PMN P-87-1471) is subject to...

40 CFR 721.1210 - Benzene, (2-chloroethoxy)-.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzene, (2-chloroethoxy)-. 721.1210... Substances § 721.1210 Benzene, (2-chloroethoxy)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (2-chloroethoxy)- (PMN P-87-1471) is subject to...

40 CFR 721.1210 - Benzene, (2-chloroethoxy)-.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzene, (2-chloroethoxy)-. 721.1210... Substances § 721.1210 Benzene, (2-chloroethoxy)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (2-chloroethoxy)- (PMN P-87-1471) is subject to...

40 CFR 721.1210 - Benzene, (2-chloroethoxy)-.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzene, (2-chloroethoxy)-. 721.1210... Substances § 721.1210 Benzene, (2-chloroethoxy)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (2-chloroethoxy)- (PMN P-87-1471) is subject to...

Benzene as a Chemical Hazard in Processed Foods.

PubMed

Salviano Dos Santos, Vânia Paula; Medeiros Salgado, Andréa; Guedes Torres, Alexandre; Signori Pereira, Karen

2015-01-01

This paper presents a literature review on benzene in foods, including toxicological aspects, occurrence, formation mechanisms, and mitigation measures and analyzes data reporting benzene levels in foods. Benzene is recognized by the IARC (International Agency for Research on Cancer) as carcinogenic to humans, and its presence in foods has been attributed to various potential sources: packaging, storage environment, contaminated drinking water, cooking processes, irradiation processes, and degradation of food preservatives such as benzoates. Since there are no specific limits for benzene levels in beverages and food in general studies have adopted references for drinking water in a range from 1-10 ppb. The presence of benzene has been reported in various food/beverage substances with soft drinks often reported in the literature. Although the analyses reported low levels of benzene in most of the samples studied, some exceeded permissible limits. The available data on dietary exposure to benzene is minimal from the viewpoint of public health. Often benzene levels were low as to be considered negligible and not a consumer health risk, but there is still a need of more studies for a better understanding of their effects on human health through the ingestion of contaminated food.

Microbial succession in a compost-packed biofilter treating benzene-contaminated air.

PubMed

Borin, Sara; Marzorati, Massimo; Brusetti, Lorenzo; Zilli, Mario; Cherif, Hanene; Hassen, Abdennaceur; Converti, Attilio; Sorlini, Claudia; Daffonchio, Daniele

2006-03-01

Air artificially contaminated with increasing concentrations of benzene was treated in a laboratory scale compost-packed biofilter for 240 days with a removal efficiency of 81-100%. The bacterial community in the packing material (PM) at different heights of the biofilter was analysed every 60 days. Bacterial plate counts and ribosomal intergenic spacer analysis (RISA) of the isolated strains showed that the number of cultivable aerobic heterotrophic bacteria and the species diversity increased with benzene availability. Identification of the isolated species and the main bands in denaturing gradient gel electrophoresis (DGGE) profiles from total compost DNA during the treatment revealed that, at a relatively low volumetric benzene load (1.2< or =VBL< or =6.4 g m(-3) (PM) h(-1)), besides low G+C Gram positive bacteria, originally present in the packing compost, bacteroidetes and beta- and gamma-proteobacteria became detectable in the colonising population. At the VBL value (24.8 g m(-3) (PM) h(-1)) ensuring the maximum elimination capacity of the biofilter (20.1 g m(-3) (PM) h(-1)), strains affiliated to the genus Rhodococcus dominated the microflora, followed by beta-proteobacteria comprising the genera Bordetella and Neisseria. Under these conditions, more than 35% of the isolated strains were able to grow on benzene as the sole carbon source. Comparison of DGGE and automated RISA profiles of the total community and isolated strains showed that a complex bacterial succession occurred in the reactor in response to the increasing concentrations of the pollutant and that cultivable bacteria played a major role in benzene degradation under the adopted conditions.

Benzene exposure monitoring of Tunisian workers.

PubMed

Chakroun, Radhouane; Kaabachi, Néziha; Hedhili, Abderrazek; Feki, Moncef; Nouaigui, Habib; Ben Laiba, Mohamed; Mebazaa, Abderraouf

2002-12-01

To monitor benzene exposure and to check reliability of urinary trans,trans-Muconic Acid (t,t-MA) as a bio-marker of benzene exposure in local conditions, a study was conducted on 30 Tunisian exposed workers (20 tanker fillers and 10 filling station attendants). The analyses were carried out on environmental air and urinary t,t-MA before (t,t-MAA) and at the end of work shift (t,t-MAB). 20 nonoccupationally exposed subjects were also investigated. The average value of environmental benzene concentration was 0.17 ppm. The differences between t,t-MAA and t,t-MAB concentrations and between t,t-MAB and t,t-MA measured in controls (t,t-MAC) were both significant (p < 0.001). Benzene air concentrations were well correlated with t,t-MAB: R = 0.76. In the nonexposed group, average t,t-MA concentrations is significantly higher among smokers than nonsmokers (P < 0.02). Analysis of urinary t,t-MA offers a relatively simple and suitable method for benzene exposure monitoring.

Determinants of indoor benzene in Europe

NASA Astrophysics Data System (ADS)

Lai, H. K.; Jantunen, M. J.; Künzli, N.; Kulinskaya, E.; Colvile, R.; Nieuwenhuijsen, M. J.

This study identified the key determinants associated with the indoor benzene concentrations that were measured between 1996 and 2000 using the EXPOLIS protocol in the residences of six European cities, including Athens (Greece), Basel (Switzerland), Helsinki (Finland), Milan (Italy), Oxford (United Kingdom), and Prague (Czech Republic). Two consecutive days of home indoor and home outdoor measurements of benzene were carried out at the homes of adult participants on different dates and seasons during the sampling period. Regression models, with interactions searched by all-possible subset method, were used to assess the city effects and the determinants of home indoor benzene (adjusted R2=0.57, n=412). Outdoor benzene concentrations, outdoor temperature, wind speed, the use of anti-moth products, and indoor smoking in terms of number of cigarettes consumed per day were shown to be the key determinants of indoor benzene concentrations. The model was further used to predict the indoor benzene levels in cities. Non-linear relationships were commonly found, indicating that a unit change in the indoor concentration cannot be simply estimated by a proportional change of the determinant, and the pattern of relationships could be differed in different places. This finding is important in formulating indoor air quality guidelines as well as calculating an accurate health risk estimate based on the estimates of population's lifetime exposure levels.

Dinuclear Cu(II) complexes of isomeric bis-(3-acetylacetonate)benzene ligands: synthesis, structure, and magnetic properties.

PubMed

Rancan, Marzio; Dolmella, Alessandro; Seraglia, Roberta; Orlandi, Simonetta; Quici, Silvio; Sorace, Lorenzo; Gatteschi, Dante; Armelao, Lidia

2012-05-07

Highly versatile coordinating ligands are designed and synthesized with two β-diketonate groups linked at the carbon 3 through a phenyl ring. The rigid aromatic spacer is introduced in the molecules to orient the two acetylacetone units along different angles and coordination vectors. The resulting para, meta, and ortho bis-(3-acetylacetonate)benzene ligands show efficient chelating properties toward Cu(II) ions. In the presence of 2,2'-bipyridine, they promptly react and yield three dimers, 1, 2, and 3, with the bis-acetylacetonate unit in bridging position between two metal centers. X-ray single crystal diffraction shows that the compounds form supramolecular chains in the solid state because of intermolecular interactions. Each of the dinuclear complexes shows a magnetic behavior which is determined by the combination of structural parameters and spin polarization effects. Notably, the para derivative (1) displays a moderate antiferromagnetic coupling (J = -3.3 cm(-1)) along a remarkably long Cu···Cu distance (12.30 Å).

Benzene formation in Titan's lower atmosphere

NASA Astrophysics Data System (ADS)

Plane, J. M. C.; Douglas, K.; Blitz, M. A.; Heard, D. E.; Seakins, P. W.; Feng, W.; Willacy, K.

2017-09-01

The most distinctive feature of Saturn's moon Titan is that it is covered in a thick haze. The haze consists of organic particles called tholins, of which benzene is thought to be an important precursor. Here we examine two pathways to form benzene. The first involves reactions on cosmic dust particles, which mostly do not ablate when entering Titan's atmosphere and accumulate in the lower atmosphere. We have shown in the laboratory that acetylene molecules stick on synthetic cosmic dust at low temperatures, and react efficiently to make benzene. The second pathway is through gas phase reactions involving radical species formed through methane photochemistry. A new lab study shows that the rates of critical reactions involving these radicals vary unexpectedly at low temperatures, leading to significant changes in important benzene precursors.

Inorganic benzenes as the noncovalent interaction donor: a study of the π-hole interactions.

PubMed

Chu, Runtian; Zhang, Xueying; Meng, Lingpeng; Zeng, Yanli

2017-11-08

For inorganic benzenes C 3 N 3 X 3 and B 3 O 3 X 3 (X = H, F, CN), the positive electrostatic potentials (π-hole) were discovered above and below the inorganic benzene ring center. Then, the π-hole interactions between the inorganic benzenes and NCH have been designed and investigated by MP2/aug-cc-pVDZ calculations. In this paper, the termolecular complexes B 3 O 3 X 3 ···NCH···NCH, C 3 N 3 X 3 ···NCH···NCH (X = H, F, CN) were also designed to illustrate the enhancing effects of the H···N hydrogen bond on the π-hole interactions. The π-hole interaction energy was influenced by the strength of different electron-withdrawing substituents of inorganic benzenes, gradually increasing in the order of X = H, F, CN. What's more, the π electron densities account for 71~88% of the total electron densities, indicating the strength of interaction energy is mainly determined by π-type electron densities. Graphical abstract The termolecular complexes B 3 O 3 X 3 ···NCH···NCH, C 3 N 3 X 3 ···NCH···NCH (X = H, F, CN) were designed to illustrate the enhancing effects of the H···N hydrogen bond on the π-hole interactions.

Benzene as a Chemical Hazard in Processed Foods

PubMed Central

Salviano dos Santos, Vânia Paula; Medeiros Salgado, Andréa; Guedes Torres, Alexandre; Signori Pereira, Karen

2015-01-01

This paper presents a literature review on benzene in foods, including toxicological aspects, occurrence, formation mechanisms, and mitigation measures and analyzes data reporting benzene levels in foods. Benzene is recognized by the IARC (International Agency for Research on Cancer) as carcinogenic to humans, and its presence in foods has been attributed to various potential sources: packaging, storage environment, contaminated drinking water, cooking processes, irradiation processes, and degradation of food preservatives such as benzoates. Since there are no specific limits for benzene levels in beverages and food in general studies have adopted references for drinking water in a range from 1–10 ppb. The presence of benzene has been reported in various food/beverage substances with soft drinks often reported in the literature. Although the analyses reported low levels of benzene in most of the samples studied, some exceeded permissible limits. The available data on dietary exposure to benzene is minimal from the viewpoint of public health. Often benzene levels were low as to be considered negligible and not a consumer health risk, but there is still a need of more studies for a better understanding of their effects on human health through the ingestion of contaminated food. PMID:26904662

Benzene exposure is associated with epigenetic changes (Review).

PubMed

Fenga, Concettina; Gangemi, Silvia; Costa, Chiara

2016-04-01

Benzene is a volatile aromatic hydrocarbon solvent and is known as one of the predominant air pollutants in the environment. Chronic exposure to benzene is known to cause aplastic anemia and increased risk of acute myelogenous leukemia in humans. Although the mechanisms by which benzene causes toxicity remain to be fully elucidated, it is widely accepted that its metabolism is crucial to its toxicity, with involvement of one or more reactive metabolites. Novel approaches aimed at evaluating different mechanisms by which benzene can impact on human health by altering gene regulation have been developed. Among these novel approaches, epigenetics appears to be promising. The present review article summarizes the most important findings, reported from the literature, on epigenetic modifications correlated to benzene exposure. A computerized search in PubMed was performed in November 2014, using search terms, including 'benzene', 'epigenetic', 'histone modifications', 'DNA methylation' and 'microRNA'. Epidemiological and experimental studies have demonstrated the potential epigenetic effects of benzene exposure. Several of the epigenomic changes observed in response to environmental exposures may be mechanistically associated with susceptibility to diseases. However, further elucidation of the mechanisms by which benzene alters gene expression may improve prediction of the toxic potential of novel compounds introduced into the environment, and allow for more targeted and appropriate disease prevention strategies.

Intercalation of Transition Metals into Stacked Benzene Rings: A Model Study of the Intercalation of Transition Metals into Bilayered Graphene.

PubMed

Youn, Il Seung; Kim, Dong Young; Singh, N Jiten; Park, Sung Woo; Youn, Jihee; Kim, Kwang S

2012-01-10

Structures of neutral metal-dibenzene complexes, M(C6H6)2 (M = Sc-Zn), are investigated by using Møller-Plesset second order perturbation theory (MP2). The benzene molecules change their conformation and shape upon complexation with the transition metals. We find two types of structures: (i) stacked forms for early transition metal complexes and (ii) distorted forms for late transition metal ones. The benzene molecules and the metal atom are bound together by δ bonds which originate from the interaction of π-MOs and d orbitals. The binding energy shows a maximum for Cr(C6H6)2, which obeys the 18-electron rule. It is noticeable that Mn(C6H6)2, a 19-electron complex, manages to have a stacked structure with an excess electron delocalized. For other late transition metal complexes having more than 19 electrons, the benzene molecules are bent or stray away from each other to reduce the electron density around a metal atom. For the early transition metals, the M(C6H6) complexes are found to be more weakly bound than M(C6H6)2. This is because the M(C6H6) complexes do not have enough electrons to satisfy the 18-electron rule, and so the M(C6H6)2 complexes generally tend to have tighter binding with a shorter benzene-metal length than the M(C6H6) complexes, which is quite unusual. The present results could provide a possible explanation of why on the Ni surface graphene tends to grow in a few layers, while on the Cu surface the weak interaction between the copper surface and graphene allows for the formation of a single layer of graphene, in agreement with chemical vapor deposition experiments.

Benzene derivatives produced by Fusarium graminearum - Short communication.

PubMed

Ntushelo, Khayalethu; Setshedi, Itumeleng

2015-06-01

Using NMR spectroscopy benzene derivatives were detected in mycelia of Fusarium graminearum, a pathogen of wheat and maize. In previous studies F. graminearum was found to cause cancer to humans and benzene derivatives were detected in breath of cancer sufferers. Surprisingly, no study found benzene derivatives to be the cancerous agents in F. graminearum. In this study we detected benzene derivatives in F. graminearum and propose to study their role as cancer agents.

46 CFR 197.565 - Notifying personnel of benzene hazards.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Notifying personnel of benzene hazards. 197.565 Section... AND HEALTH STANDARDS GENERAL PROVISIONS Benzene § 197.565 Notifying personnel of benzene hazards. (a) Material safety data sheet. A material safety data sheet (MSDS) addressing benzene must be made available...

46 CFR 197.565 - Notifying personnel of benzene hazards.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Notifying personnel of benzene hazards. 197.565 Section... AND HEALTH STANDARDS GENERAL PROVISIONS Benzene § 197.565 Notifying personnel of benzene hazards. (a) Material safety data sheet. A material safety data sheet (MSDS) addressing benzene must be made available...

46 CFR 197.565 - Notifying personnel of benzene hazards.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Notifying personnel of benzene hazards. 197.565 Section... AND HEALTH STANDARDS GENERAL PROVISIONS Benzene § 197.565 Notifying personnel of benzene hazards. (a) Material safety data sheet. A material safety data sheet (MSDS) addressing benzene must be made available...

Clusters of imidazolium-based ionic liquid in benzene solutions.

PubMed

Shimomura, Takuya; Takamuku, Toshiyuki; Yamaguchi, Toshio

2011-07-07

Cluster formation of 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide (C(12)mim(+)TFSA(-)) in benzene solutions was investigated using small-angle neutron scattering (SANS), NMR, attenuated total reflectance infrared (ATR-IR), and large-angle X-ray scattering (LAXS) techniques. The SANS measurements revealed that C(12)mim(+)TFSA(-) is heterogeneously mixed with benzene in the narrow range of benzene mole fraction 0.9 ≤ x(C6D6) ≤ 0.995 with a maximum heterogeneity at x(C6D6) ≈ 0.99. The NMR results suggested that the imidazolium ring is sandwiched between benzene molecules through the cation-π interaction. Moreover, TFSA(-) probably interacts with the imidazolium ring even in the range of x(C6H6) ≥ 0.9. Thus, the imidazolium rings, benzene molecules, and TFSA(-) would form clusters in the C(12)mim(+)TFSA(-)-benzene solutions. The LAXS measurements showed that the distance between the imidazolium ring and benzene is ∼3.8 Å with that between the benzene molecules of ∼7.5 Å. On the basis of these results, we discussed a plausible reason for the liquid-liquid equilibrium of the C(12)mim(+)TFSA(-)-benzene system.

Alkali-ion microsolvation with benzene molecules.

PubMed

Marques, J M C; Llanio-Trujillo, J L; Albertí, M; Aguilar, A; Pirani, F

2012-05-24

The target of this investigation is to characterize by a recently developed methodology, the main features of the first solvation shells of alkaline ions in nonpolar environments due to aromatic rings, which is of crucial relevance to understand the selectivity of several biochemical phenomena. We employ an evolutionary algorithm to obtain putative global minima of clusters formed with alkali-ions (M(+)) solvated with n benzene (Bz) molecules, i.e., M(+)-(Bz)(n). The global intermolecular interaction has been decomposed in Bz-Bz and in M(+)-Bz contributions, using a potential model based on different decompositions of the molecular polarizability of benzene. Specifically, we have studied the microsolvation of Na(+), K(+), and Cs(+) with benzene molecules. Microsolvation clusters up to n = 21 benzene molecules are involved in this work and the achieved global minimum structures are reported and discussed in detail. We observe that the number of benzene molecules allocated in the first solvation shell increases with the size of the cation, showing three molecules for Na(+) and four for both K(+) and Cs(+). The structure of this solvation shell keeps approximately unchanged as more benzene molecules are added to the cluster, which is independent of the ion. Particularly stable structures, so-called "magic numbers", arise for various nuclearities of the three alkali-ions. Strong "magic numbers" appear at n = 2, 3, and 4 for Na(+), K(+), and Cs(+), respectively. In addition, another set of weaker "magic numbers" (three per alkali-ion) are reported for larger nuclearities.

Biomarkers of environmental benzene exposure.

PubMed Central

Weisel, C; Yu, R; Roy, A; Georgopoulos, P

1996-01-01

Environmental exposures to benzene result in increases in body burden that are reflected in various biomarkers of exposure, including benzene in exhaled breath, benzene in blood and urinary trans-trans-muconic acid and S-phenylmercapturic acid. A review of the literature indicates that these biomarkers can be used to distinguish populations with different levels of exposure (such as smokers from nonsmokers and occupationally exposed from environmentally exposed populations) and to determine differences in metabolism. Biomarkers in humans have shown that the percentage of benzene metabolized by the ring-opening pathway is greater at environmental exposures than that at higher occupational exposures, a trend similar to that found in animal studies. This suggests that the dose-response curve is nonlinear; that potential different metabolic mechanisms exist at high and low doses; and that the validity of a linear extrapolation of adverse effects measured at high doses to a population exposed to lower, environmental levels of benzene is uncertain. Time-series measurements of the biomarker, exhaled breath, were used to evaluate a physiologically based pharmacokinetic (PBPK) model. Biases were identified between the PBPK model predictions and experimental data that were adequately described using an empirical compartmental model. It is suggested that a mapping of the PBPK model to a compartmental model can be done to optimize the parameters in the PBPK model to provide a future framework for developing a population physiologically based pharmacokinetic model. PMID:9118884

The contribution of benzene to smoking-induced leukemia.

PubMed

Korte, J E; Hertz-Picciotto, I; Schulz, M R; Ball, L M; Duell, E J

2000-04-01

Cigarette smoking is associated with an increased risk of leukemia; benzene, an established leukemogen, is present in cigarette smoke. By combining epidemiologic data on the health effects of smoking with risk assessment techniques for low-dose extrapolation, we assessed the proportion of smoking-induced total leukemia and acute myeloid leukemia (AML) attributable to the benzene in cigarette smoke. We fit both linear and quadratic models to data from two benzene-exposed occupational cohorts to estimate the leukemogenic potency of benzene. Using multiple-decrement life tables, we calculated lifetime risks of total leukemia and AML deaths for never, light, and heavy smokers. We repeated these calculations, removing the effect of benzene in cigarettes based on the estimated potencies. From these life tables we determined smoking-attributable risks and benzene-attributable risks. The ratio of the latter to the former constitutes the proportion of smoking-induced cases attributable to benzene. Based on linear potency models, the benzene in cigarette smoke contributed from 8 to 48% of smoking-induced total leukemia deaths [95% upper confidence limit (UCL), 20-66%], and from 12 to 58% of smoking-induced AML deaths (95% UCL, 19-121%). The inclusion of a quadratic term yielded results that were comparable; however, potency models with only quadratic terms resulted in much lower attributable fractions--all < 1%. Thus, benzene is estimated to be responsible for approximately one-tenth to one-half of smoking-induced total leukemia mortality and up to three-fifths of smoking-related AML mortality. In contrast to theoretical arguments that linear models substantially overestimate low-dose risk, linear extrapolations from empirical data over a dose range of 10- to 100-fold resulted in plausible predictions.

Benzene exposure is associated with cardiovascular disease risk.

PubMed

Abplanalp, Wesley; DeJarnett, Natasha; Riggs, Daniel W; Conklin, Daniel J; McCracken, James P; Srivastava, Sanjay; Xie, Zhengzhi; Rai, Shesh; Bhatnagar, Aruni; O'Toole, Timothy E

2017-01-01

Benzene is a ubiquitous, volatile pollutant present at high concentrations in toxins (e.g. tobacco smoke) known to increase cardiovascular disease (CVD) risk. Despite its prevalence, the cardiovascular effects of benzene have rarely been studied. Hence, we examined whether exposure to benzene is associated with increased CVD risk. The effects of benzene exposure in mice were assessed by direct inhalation, while the effects of benzene exposure in humans was assessed in 210 individuals with mild to high CVD risk by measuring urinary levels of the benzene metabolite trans,trans-muconic acid (t,t-MA). Generalized linear models were used to assess the association between benzene exposure and CVD risk. Mice inhaling volatile benzene had significantly reduced levels of circulating angiogenic cells (Flk-1+/Sca-1+) as well as an increased levels of plasma low-density lipoprotein (LDL) compared with control mice breathing filtered air. In the human cohort, urinary levels of t,t-MA were inversely associated several populations of circulating angiogenic cells (CD31+/34+/45+, CD31+/34+/45+/AC133-, CD34+/45+/AC133+). Although t,t-MA was not associated with plasma markers of inflammation or thrombosis, t,t-MA levels were higher in smokers and in individuals with dyslipidemia. In smokers, t,t-MA levels were positively associated with urinary metabolites of nicotine (cotinine) and acrolein (3-hydroxymercapturic acid). Levels of t,t-MA were also associated with CVD risk as assessed using the Framingham Risk Score and this association was independent of smoking. Thus, benzene exposure is associated with increased CVD risk and deficits in circulating angiogenic cells in both smokers and non-smokers.

Benzene exposure is associated with cardiovascular disease risk

PubMed Central

Riggs, Daniel W.; Conklin, Daniel J.; McCracken, James P.; Srivastava, Sanjay; Xie, Zhengzhi; Rai, Shesh; Bhatnagar, Aruni; O’Toole, Timothy E.

2017-01-01

Benzene is a ubiquitous, volatile pollutant present at high concentrations in toxins (e.g. tobacco smoke) known to increase cardiovascular disease (CVD) risk. Despite its prevalence, the cardiovascular effects of benzene have rarely been studied. Hence, we examined whether exposure to benzene is associated with increased CVD risk. The effects of benzene exposure in mice were assessed by direct inhalation, while the effects of benzene exposure in humans was assessed in 210 individuals with mild to high CVD risk by measuring urinary levels of the benzene metabolite trans,trans-muconic acid (t,t-MA). Generalized linear models were used to assess the association between benzene exposure and CVD risk. Mice inhaling volatile benzene had significantly reduced levels of circulating angiogenic cells (Flk-1+/Sca-1+) as well as an increased levels of plasma low-density lipoprotein (LDL) compared with control mice breathing filtered air. In the human cohort, urinary levels of t,t-MA were inversely associated several populations of circulating angiogenic cells (CD31+/34+/45+, CD31+/34+/45+/AC133–, CD34+/45+/AC133+). Although t,t-MA was not associated with plasma markers of inflammation or thrombosis, t,t-MA levels were higher in smokers and in individuals with dyslipidemia. In smokers, t,t-MA levels were positively associated with urinary metabolites of nicotine (cotinine) and acrolein (3-hydroxymercapturic acid). Levels of t,t-MA were also associated with CVD risk as assessed using the Framingham Risk Score and this association was independent of smoking. Thus, benzene exposure is associated with increased CVD risk and deficits in circulating angiogenic cells in both smokers and non-smokers. PMID:28886060

Volatilization of benzene and eight alkyl-substituted benzene compounds from water

USGS Publications Warehouse

Rathbun, R.E.; Tai, D.Y.

1988-01-01

Predicting the fate of organic compounds in streams and rivers often requires knowledge of the volatilization characteristics of the compounds. The reference-substance concept, involving laboratory-determined ratios of the liquid-film coefficients for volatilization of the organic compounds to the liquid-film coefficient for oxygen absorption, is used to predict liquid-film coefficients for streams and rivers. In the absence of experimental data, two procedures have been used for estimating these liquid-film coefficient ratios. These procedures, based on the molecular-diffusion coefficient and on the molecular weight, have been widely used but never extensively evaluated. Liquid-film coefficients for the volatilization of benzene and eight alkyl-substituted benzene compounds (toluene through n-octylbenzene) from water were measured in a constant-temperature, stirred water bath. Liquid-film coefficients for oxygen absorption were measured simultaneously. A range of water mixing conditions was used with a water temperature of 298.2 K. The ratios of the liquid-film coefficients for volatilization to the liquid-film coefficient for oxygen absorption for all of the organic compounds were independent of mixing conditions in the water. Experimental ratios ranged from 0.606 for benzene to 0.357 for n-octylbenzene. The molecular-diffusion-coefficient procedure accurately predicted the ratios for ethylbenzene through n-pentylbenzene with a power dependence of 0.566 on the molecular-diffusion coefficient, in agreement with published values. Predicted ratios for benzene and toluene were slightly larger than the experimental ratios. These differences were attributed to possible interactions between the molecules of these compounds and the water molecules and to benzene-benzene interactions that form dimers. Because these interactions also are likely to occur in natural waters, it was concluded that the experimental ratios are more correct than the predicted ratios for

Reactions of benzene oxide with thiols including glutathione.

PubMed

Henderson, Alistair P; Barnes, Martine L; Bleasdale, Christine; Cameron, Richard; Clegg, William; Heath, Sarah L; Lindstrom, Andrew B; Rappaport, Stephen M; Waidyanatha, Suramya; Watson, William P; Golding, Bernard T

2005-02-01

S-Phenylmercapturic acid is a minor metabolite of benzene used as a biomarker for human benzene exposures. The reaction of intracellular glutathione with benzene oxide-oxepin, the initial metabolite of benzene, is presumed to give 1-(S-glutathionyl)-cyclohexa-3,5-dien-2-ol, which undergoes dehydration to S-phenylglutathione, the precursor of S-phenylmercapturic acid. To validate the proposed route to S-phenylglutathione, reactions of benzene oxide-oxepin with glutathione and other sulfur nucleophiles have been studied. The reaction of benzene oxide with an excess of aqueous sodium sulfide, followed by acetylation, gave bis-(6-trans-5-acetoxycyclohexa-1,3-dienyl)sulfide, the structure of which was proved by X-ray crystallography. Reactions of benzene oxide-oxepin in a 95:5 (v/v) mixture of phosphate buffer in D2O with (CD3)2SO were monitored by 1H NMR spectroscopy. In the absence of glutathione, the half-life of benzene oxide-oxepin was ca. 34 min at 25 degrees C and pD 7.0. The half-life was not affected in the range of 2-15 mM glutathione in the presence and absence of a commercial sample of human glutathione S-transferase (at pH 7.0, 8.0, 8.5, or 10.0). The adduct 1-(S-glutathionyl)-cyclohexa-3,5-diene-2-ol was identified in these reaction mixtures, especially at higher pH, by mass spectrometry and by its acid-catalyzed decomposition to S-phenylglutathione. Incubation of benzene oxide with N-acetyl-L-cysteine at 37 degrees C and pH 10.0 and subsequent mass spectrometric analysis of the mixture showed formation of pre-S-phenylmercapturic acid and the dehydration product, S-phenylmercapturic acid. The data validate the premise that benzene oxide-oxepin can be captured by glutathione to give (1R,2R)- and/or (1S,2S)-1-(S-glutathionyl)-cyclohexa-3,5-dien-2-ol, which dehydrate to S-phenylglutathione. The capture is a relatively inefficient process at pH 7 that is accelerated at higher pH. These studies account for the observation that the metabolism of benzene is

Species comparison of hepatic and pulmonary metabolism of benzene.

PubMed

Powley, M W; Carlson, G P

1999-12-06

Benzene is an occupational hazard and environmental toxicant found in cigarette smoke, gasoline, and the chemical industry. The major health concern associated with benzene exposure is leukemia. Studies using microsomal preparations from human, mouse, rabbit, and rat to determine species differences in the metabolism of benzene to phenol, hydroquinone and catechol, indicate that the rat is most similar, both quantitatively and qualitatively, to the human in pulmonary microsomal metabolism of benzene. With hepatic microsomes, rat is most similar to human in metabolite formation at the two lower concentrations examined (24 and 200 microM), while at the two higher concentrations (700 and 1000 microM) mouse is most similar in phenol formation. In all species, the enzyme system responsible for benzene metabolism approached saturation in hepatic microsomes but not in pulmonary microsomes. In pulmonary microsomes from mouse, rat, and human, phenol appeared to competitively inhibit benzene metabolism resulting in a greater proportion of phenol being converted to hydroquinone when the benzene concentration increased. The opposite effect was seen in hepatic microsomes. These findings support the hypothesis that the lung plays an important role in benzene metabolism, and therefore, toxicity.

Adsorption of benzene on low index surfaces of platinum in the presence of van der Waals interactions

NASA Astrophysics Data System (ADS)

K, Ayishabi P.; Chatanathodi, Raghu

2017-10-01

We have studied the adsorption of benzene on three low index surfaces of platinum using plane-wave Density Functional Theory (DFT) calculations, taking into consideration van der Waals (vdW) interaction. Experimentally, it is known that benzene adsorbs at the bridge site on the (111) surface, but in case of (110) and (100), this is not known yet. Our calculations show that benzene preferably adsorbs on bridge position on Pt(111) surface, whereas on Pt(110) and Pt(100) surfaces, the hollow position is energetically more favoured. The structural and electronic modifications of molecule and the surfaces are also examined. In all cases, adsorption-induced distortions of adsorbate-substrate complex are found to be modest in character, but relatively maximum in case of the (110) facet. The molecule is bound most strongly to the (110) surface. Importantly, we find that adsorption at bridge and atop positions are energetically feasible on the (110) surface, with the canting of benzene ring at a small angle from the metal plane. We study changes in electronic structure and the net charge transfer upon adsorption of benzene on all three low index planes. Inclusion of vdW interactions is important for obtaining realistic adsorption strengths for benzene on various Pt facets.

40 CFR 80.1280 - How are refinery benzene baselines calculated?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 17 2014-07-01 2014-07-01 false How are refinery benzene baselines... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1280 How are refinery benzene baselines calculated? (a) A refinery's benzene...

40 CFR 80.1280 - How are refinery benzene baselines calculated?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 17 2012-07-01 2012-07-01 false How are refinery benzene baselines... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1280 How are refinery benzene baselines calculated? (a) A refinery's benzene...

40 CFR 80.1280 - How are refinery benzene baselines calculated?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false How are refinery benzene baselines... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1280 How are refinery benzene baselines calculated? (a) A refinery's benzene...

40 CFR 80.1280 - How are refinery benzene baselines calculated?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 16 2011-07-01 2011-07-01 false How are refinery benzene baselines... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1280 How are refinery benzene baselines calculated? (a) A refinery's benzene...

40 CFR 80.1280 - How are refinery benzene baselines calculated?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 17 2013-07-01 2013-07-01 false How are refinery benzene baselines... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1280 How are refinery benzene baselines calculated? (a) A refinery's benzene...

Anaerobic Oxidation of Benzene by the Hyperthermophilic Archaeon Ferroglobus placidus▿†

PubMed Central

Holmes, Dawn E.; Risso, Carla; Smith, Jessica A.; Lovley, Derek R.

2011-01-01

Anaerobic benzene oxidation coupled to the reduction of Fe(III) was studied in Ferroglobus placidus in order to learn more about how such a stable molecule could be metabolized under strict anaerobic conditions. F. placidus conserved energy to support growth at 85°C in a medium with benzene provided as the sole electron donor and Fe(III) as the sole electron acceptor. The stoichiometry of benzene loss and Fe(III) reduction, as well as the conversion of [14C]benzene to [14C]carbon dioxide, was consistent with complete oxidation of benzene to carbon dioxide with electron transfer to Fe(III). Benzoate, but not phenol or toluene, accumulated at low levels during benzene metabolism, and [14C]benzoate was produced from [14C]benzene. Analysis of gene transcript levels revealed increased expression of genes encoding enzymes for anaerobic benzoate degradation during growth on benzene versus growth on acetate, but genes involved in phenol degradation were not upregulated during growth on benzene. A gene for a putative carboxylase that was more highly expressed in benzene- than in benzoate-grown cells was identified. These results suggest that benzene is carboxylated to benzoate and that phenol is not an important intermediate in the benzene metabolism of F. placidus. This is the first demonstration of a microorganism in pure culture that can grow on benzene under strict anaerobic conditions and for which there is strong evidence for degradation of benzene via clearly defined anaerobic metabolic pathways. Thus, F. placidus provides a much-needed pure culture model for further studies on the anaerobic activation of benzene in microorganisms. PMID:21742914

Enumerating Substituted Benzene Isomers of Tree-Like Chemical Graphs.

PubMed

Li, Jinghui; Nagamochi, Hiroshi; Akutsu, Tatsuya

2018-01-01

Enumeration of chemical structures is useful for drug design, which is one of the main targets of computational biology and bioinformatics. A chemical graph with no other cycles than benzene rings is called tree-like, and becomes a tree possibly with multiple edges if we contract each benzene ring into a single virtual atom of valence 6. All tree-like chemical graphs with a given tree representation are called the substituted benzene isomers of . When we replace each virtual atom in with a benzene ring to obtain a substituted benzene isomer, distinct isomers of are caused by the difference in arrangements of atom groups around a benzene ring. In this paper, we propose an efficient algorithm that enumerates all substituted benzene isomers of a given tree representation . Our algorithm first counts the number of all the isomers of the tree representation by a dynamic programming method. To enumerate all the isomers, for each , our algorithm then generates the th isomer by backtracking the counting phase of the dynamic programming. We also implemented our algorithm for computational experiments.

40 CFR 80.1295 - How are gasoline benzene credits used?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false How are gasoline benzene credits used... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1295 How are gasoline benzene credits used? (a) Credit use. (1) Gasoline benzene...

40 CFR 80.1295 - How are gasoline benzene credits used?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 17 2012-07-01 2012-07-01 false How are gasoline benzene credits used... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1295 How are gasoline benzene credits used? (a) Credit use. (1) Gasoline benzene...

40 CFR 80.1295 - How are gasoline benzene credits used?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 17 2014-07-01 2014-07-01 false How are gasoline benzene credits used... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1295 How are gasoline benzene credits used? (a) Credit use. (1) Gasoline benzene...

40 CFR 80.1295 - How are gasoline benzene credits used?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 17 2013-07-01 2013-07-01 false How are gasoline benzene credits used... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1295 How are gasoline benzene credits used? (a) Credit use. (1) Gasoline benzene...

40 CFR 80.1295 - How are gasoline benzene credits used?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 16 2011-07-01 2011-07-01 false How are gasoline benzene credits used... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1295 How are gasoline benzene credits used? (a) Credit use. (1) Gasoline benzene...

46 CFR 151.50-60 - Benzene.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Benzene. 151.50-60 Section 151.50-60 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-60 Benzene. The person in charge of a...

46 CFR 151.50-60 - Benzene.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Benzene. 151.50-60 Section 151.50-60 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-60 Benzene. The person in charge of a...

46 CFR 151.50-60 - Benzene.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Benzene. 151.50-60 Section 151.50-60 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-60 Benzene. The person in charge of a...

46 CFR 151.50-60 - Benzene.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Benzene. 151.50-60 Section 151.50-60 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-60 Benzene. The person in charge of a...

46 CFR 151.50-60 - Benzene.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Benzene. 151.50-60 Section 151.50-60 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-60 Benzene. The person in charge of a...

Collision-induced dissociation processes of protonated benzoic acid and related compounds: competitive generation of protonated carbon dioxide or protonated benzene.

PubMed

Xu, Sihang; Pavlov, Julius; Attygalle, Athula B

2017-04-01

Upon activation in the gas phase, protonated benzoic acid (m/z 123) undergoes fragmentation by several mechanisms. In addition to the predictable water loss followed by a CO loss, the m/z 123 ion more intriguingly eliminates a molecule of benzene to generate protonated carbon dioxide (H - O +  ═ C ≡ O, m/z 45), or a molecule of carbon dioxide to yield protonated benzene (m/z 79). Experimental evidence shows that the incipient proton ambulates during the fragmentation processes. For the CO 2 or benzene loss, protonated benzoic acid transfers the charge-imparting proton initially to the ortho position and then to the ipso position to generate a transient species which dissociates to form an ion-neutral complex between benzene and protonated CO 2 . The formation of the m/z 45 ion is not a phenomenon unique to benzoic acid: spectra from protonated isophthalic acid, terephthalic acid, trans-cinnamic acid and some aliphatic acids also displayed a peak for m/z 45. However, the m/z 45 peak is structurally diagnostic only for certain benzene polycarboxylic acids because the spectra of compounds with two carboxyl groups on adjacent ring carbons do not produce a peak at m/z 45. For the m/z 79 ion to be formed, an intramolecular reaction should take place in which protonated CO 2 within the ion-neutral complex acts as the attacking electrophile to transfer a proton to benzene. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Charge transfer complex studies between some non-steroidal anti-inflammatory drugs and π-electron acceptors

NASA Astrophysics Data System (ADS)

Duymus, Hulya; Arslan, Mustafa; Kucukislamoglu, Mustafa; Zengin, Mustafa

2006-12-01

Charge transfer (CT) complexes of some non-steroidal anti-inflammatory drugs, naproxen and etodolac which are electron donors with some π-acceptors, such as tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano- p-benzoquinone (DDQ), p-chloranil ( p-CHL), have been investigated spectrophotometrically in chloroform at 21 °C. The coloured products are measured spectrophotometrically at different wavelength depending on the electronic transition between donors and acceptors. Beer's law is obeyed and colours were produced in non-aqueous media. All complexes were stable at least 2 h except for etodolac with DDQ stable for 5 min. The equilibrium constants of the CT complexes were determined by the Benesi-Hildebrand equation. The thermodynamic parameters Δ H, Δ S, Δ G° were calculated by Van't Hoff equation. Stochiometries of the complexes formed between donors and acceptors were defined by the Job's method of the continuous variation and found in 1:1 complexation with donor and acceptor at the maximum absorption bands in all cases.

Benzene: a case study in parent chemical and metabolite interactions.

PubMed

Medinsky, M A; Kenyon, E M; Schlosser, P M

1995-12-28

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene in humans are well documented and include aplastic anemia and pancytopenia, and acute myelogenous leukemia. A combination of metabolites (hydroquinone and phenol for example) is apparently necessary to duplicate the hematotoxic effect of benzene, perhaps due in part to the synergistic effect of phenol on myeloperoxidase-mediated oxidation of hydroquinone to the reactive metabolite benzoquinone. Since benzene and its hydroxylated metabolites (phenol, hydroquinone and catechol) are substrates for the same cytochrome P450 enzymes, competitive interactions among the metabolites are possible. In vivo data on metabolite formation by mice exposed to various benzene concentrations are consistent with competitive inhibition of phenol oxidation by benzene. In vitro studies of the metabolic oxidation of benzene, phenol and hydroquinone are consistent with the mechanism of competitive interaction among the metabolites. The dosimetry of benzene and its metabolites in the target tissue, bone marrow, depends on the balance of activation processes such as enzymatic oxidation and deactivation processes such as conjugation and excretion. Phenol, the primary benzene metabolite, can undergo both oxidation and conjugation. Thus, the potential exists for competition among various enzymes for phenol. However, zonal localization of Phase I and Phase II enzymes in various regions of the liver acinus regulates this competition. Biologically-based dosimetry models that incorporate the important determinants of benzene flux, including interactions with other chemicals, will enable prediction of target tissue doses of benzene and metabolites at low exposure concentrations relevant for humans.

Benzene construction via organocatalytic formal [3+3] cycloaddition reaction.

PubMed

Zhu, Tingshun; Zheng, Pengcheng; Mou, Chengli; Yang, Song; Song, Bao-An; Chi, Yonggui Robin

2014-09-25

The benzene unit, in its substituted forms, is a most common scaffold in natural products, bioactive molecules and polymer materials. Nearly 80% of the 200 best selling small molecule drugs contain at least one benzene moiety. Not surprisingly, the synthesis of substituted benzenes receives constant attentions. At present, the dominant methods use pre-existing benzene framework to install substituents by using conventional functional group manipulations or transition metal-catalyzed carbon-hydrogen bond activations. These otherwise impressive approaches require multiple synthetic steps and are ineffective from both economic and environmental perspectives. Here we report an efficient method for the synthesis of substituted benzene molecules. Instead of relying on pre-existing aromatic rings, here we construct the benzene core through a carbene-catalyzed formal [3+3] reaction. Given the simplicity and high efficiency, we expect this strategy to be of wide use especially for large scale preparation of biomedicals and functional materials.

Anaerobic degradation of benzene by marine sulfate-reducing bacteria

NASA Astrophysics Data System (ADS)

Musat, Florin; Wilkes, Heinz; Musat, Niculina; Kuypers, Marcel; Widdel, Friedrich

2010-05-01

Benzene, the archetypal aromatic hydrocarbon is a common constituent of crude oil and oil-refined products. As such, it can enter the biosphere through natural oil seeps or as a consequence of exploitation of fossil fuel reservoirs. Benzene is chemically very stable, due to the stabilizing aromatic electron system and to the lack of functional groups. Although the anaerobic degradation of benzene has been reported under denitrifying, sulfate-reducing and methanogenic conditions, the microorganisms involved and the initial biochemical steps of degradation remain insufficiently understood. Using marine sediment from a Mediterranean lagoon a sulfate-reducing enrichment culture with benzene as the sole organic substrate was obtained. Application of 16S rRNA gene-based methods showed that the enrichment was dominated (more than 85% of total cells) by a distinct phylotype affiliated with a clade of Deltaproteobacteria that include degraders of other aromatic hydrocarbons, such as naphthalene, ethylbenzene and m-xylene. Using benzoate as a soluble substrate in agar dilution series, several pure cultures closely related to Desulfotignum spp. and Desulfosarcina spp. were isolated. None of these strains was able to utilize benzene as a substrate and hybridizations with specific oligonucleotide probes showed that they accounted for as much as 6% of the total cells. Incubations with 13C-labeled benzene followed by Halogen in situ Hybridization - Secondary Ion Mass Spectroscopy (HISH-SIMS) analysis showed that cells of the dominant phylotype were highly enriched in 13C, while the accompanying bacteria had little or no 13C incorporation. These results demonstrate that the dominant phylotype was indeed the apparent benzene degrader. Dense-cell suspensions of the enrichment culture did not show metabolic activity toward added phenol or toluene, suggesting that benzene degradation did not proceed through anaerobic hydroxylation or methylation. Instead, benzoate was identified in

Isomer-Specific Spectroscopy of Benzene-(H2O)n, n = 6,7: Benzene's Role in Reshaping Water's Three-Dimensional Networks.

PubMed

Tabor, Daniel P; Kusaka, Ryoji; Walsh, Patrick S; Sibert, Edwin L; Zwier, Timothy S

2015-05-21

The water hexamer and heptamer are the smallest sized water clusters that support three-dimensional hydrogen-bonded networks, with several competing structures that could be altered by interactions with a solute. Using infrared-ultraviolet double resonance spectroscopy, we record isomer-specific OH stretch infrared spectra of gas-phase benzene-(H2O)(6,7) clusters that demonstrate benzene's surprising role in reshaping (H2O)(6,7). The single observed isomer of benzene-(H2O)6 incorporates an inverted book structure rather than the cage or prism. The main conformer of benzene-(H2O)7 is an inserted-cubic structure in which benzene replaces one water molecule in the S4-symmetry cube of the water octamer, inserting itself into the water cluster by engaging as a π H-bond acceptor with one water and via C-H···O donor interactions with two others. The corresponding D(2d)-symmetry inserted-cube structure is not observed, consistent with the calculated energetic preference for the S4 over the D(2d) inserted cube. A reduced-dimension model that incorporates stretch-bend Fermi resonance accounts for the spectra in detail and sheds light on the hydrogen-bonding networks themselves and on the perturbations imposed on them by benzene.

Benzene and childhood acute leukemia in Oklahoma.

PubMed

Janitz, Amanda E; Campbell, Janis E; Magzamen, Sheryl; Pate, Anne; Stoner, Julie A; Peck, Jennifer D

2017-10-01

Although childhood cancer is a leading cause of childhood mortality in the US, evidence regarding the etiology is lacking. The goal of this study was to evaluate the association between benzene, a known carcinogen, and childhood acute leukemia. We conducted a case-control study including cases diagnosed with acute leukemia between 1997 and 2012 (n = 307) from the Oklahoma Central Cancer Registry and controls matched on week of birth from birth certificates (n = 1013). We used conditional logistic regression to evaluate the association between benzene, measured with the 2005 National-Scale Air Toxics Assessment (NATA) at census tract of the birth residence, and childhood acute leukemia. We observed no differences in benzene exposure overall between cases and controls. However, when stratified by year of birth, cases born from 2005 to 2010 had a three-fold increased unadjusted odds of elevated exposure compared to controls born in this same time period (4th Quartile OR: 3.53, 95% CI: 1.35, 9.27). Furthermore, the estimates for children with acute myeloid leukemia (AML) were stronger than those with acute lymphoid leukemia, though not statistically significant. While we did not observe an association between benzene and childhood leukemia overall, our results suggest that acute leukemia is associated with increased benzene exposure among more recent births, and children with AML may have increased benzene exposure at birth. Using the NATA estimates allowed us to assess a specific pollutant at the census tract level, providing an advantage over monitor or point source data. Our study, however, cannot rule out the possibility that benzene may be a marker of other traffic-related exposures and temporal misclassification may explain the lack of an association among earlier births. Copyright © 2017 Elsevier Inc. All rights reserved.

Single metal catalysis: DFT and CAS modelling of species involved in the Fe cation assisted transformation of acetylene to benzene

NASA Astrophysics Data System (ADS)

Altun, Zikri; Bleda, Erdi; Trindle, Carl

2017-09-01

Gas phase conversion of acetylene to benzene, assisted by a single metal cation such as Fe(+), Ru(+) and Rh(+), offers an attractive prospect for application of computational modelling techniques to catalytic processes. Gas phase processes are not complicated by environmental effects and the participation of a single metal atom is a significant simplification. Still the process is complex, owing to the possibility of several low-energy spin states and the abundance of alternative structures. By density functional theory modelling using recently developed models with range and dispersion corrections, we locate and characterise a number of extreme points on the FeC6H6(+) surface, some of which have not been described previously. These include eta-1, eta-2 and eta-3 complexes of Fe(+) with the C4H4 ring. We identify new FeC6H6(+) structures as well, which may be landmarks for the Fe(+)-catalysed production of benzene from acetylene. The Fe(+) benzene complex is the most stable species on the FeC6H6 cation surface. With the abundant energy of complexation available in the isolated gas phase species, detachment of the Fe(+) and production of benzene can be efficient. We address the issue raised by other investigators whether multi-configurational self-consistent field methods are essential to the proper description of these systems. We find that the relative energy of intrinsically multi-determinant doublets is strongly affected, but judge that the density functional theory (DFT) description provides more accurate estimates of energetics and a more plausible reaction path.

Benzene exposure and risk of non-Hodgkin lymphoma.

PubMed

Smith, Martyn T; Jones, Rachael M; Smith, Allan H

2007-03-01

Exposure to benzene, an important industrial chemical and component of gasoline, is a widely recognized cause of leukemia, but its association with non-Hodgkin lymphoma (NHL) is less clear. To clarify this issue, we undertook a systematic review of all case-control and cohort studies that identified probable occupational exposures to benzene and NHL morbidity or mortality. We identified 43 case-control studies of NHL outcomes that recognized persons with probable occupational exposure to benzene. Forty of these 43 (93%) studies show some elevation of NHL risk, with 23 of 43 (53%) studies finding statistically significant associations between NHL risk and probable benzene exposure. We also identified 26 studies of petroleum refinery workers reporting morbidity or mortality for lymphomas and all neoplasms and found that in 23 (88%), the rate of lymphoma morbidity or mortality was higher than that for all neoplasms. A substantial healthy-worker effect was evident in many of the studies and a comprehensive reevaluation of these studies with appropriate adjustments should be undertaken. Numerous studies have also reported associations between benzene exposure and the induction of lymphomas in mice. Further, because benzene is similar to alkylating drugs and radiation in producing leukemia, it is plausible that it might also produce lymphoma as they do and by similar mechanisms. Potential mechanisms include immunotoxicity and the induction of double-strand breaks with subsequent chromosome damage resulting in translocations and deletions. We conclude that, overall, the evidence supports an association between occupational benzene exposure and NHL.

40 CFR 721.1230 - Benzene, ethenyl-, ar-bromo derivatives.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzene, ethenyl-, ar-bromo... Specific Chemical Substances § 721.1230 Benzene, ethenyl-, ar-bromo derivatives. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, ethenyl-, ar...

40 CFR 721.1230 - Benzene, ethenyl-, ar-bromo derivatives.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, ethenyl-, ar-bromo... Specific Chemical Substances § 721.1230 Benzene, ethenyl-, ar-bromo derivatives. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, ethenyl-, ar...

40 CFR 721.1350 - Benzene, (1-methylethyl)(2-phenylethyl)-.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzene, (1-methylethyl)(2-phenylethyl... Substances § 721.1350 Benzene, (1-methylethyl)(2-phenylethyl)-. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (1-methylethyl)(2...

40 CFR 721.1350 - Benzene, (1-methylethyl)(2-phenylethyl)-.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzene, (1-methylethyl)(2-phenylethyl... Substances § 721.1350 Benzene, (1-methylethyl)(2-phenylethyl)-. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (1-methylethyl)(2...

40 CFR 721.1230 - Benzene, ethenyl-, ar-bromo derivatives.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzene, ethenyl-, ar-bromo... Specific Chemical Substances § 721.1230 Benzene, ethenyl-, ar-bromo derivatives. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, ethenyl-, ar...

40 CFR 721.1230 - Benzene, ethenyl-, ar-bromo derivatives.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzene, ethenyl-, ar-bromo... Specific Chemical Substances § 721.1230 Benzene, ethenyl-, ar-bromo derivatives. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, ethenyl-, ar...

40 CFR 721.1350 - Benzene, (1-methylethyl)(2-phenylethyl)-.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzene, (1-methylethyl)(2-phenylethyl... Substances § 721.1350 Benzene, (1-methylethyl)(2-phenylethyl)-. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (1-methylethyl)(2...

40 CFR 721.1350 - Benzene, (1-methylethyl)(2-phenylethyl)-.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzene, (1-methylethyl)(2-phenylethyl... Substances § 721.1350 Benzene, (1-methylethyl)(2-phenylethyl)-. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (1-methylethyl)(2...

40 CFR 721.1350 - Benzene, (1-methylethyl)(2-phenylethyl)-.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, (1-methylethyl)(2-phenylethyl... Substances § 721.1350 Benzene, (1-methylethyl)(2-phenylethyl)-. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (1-methylethyl)(2...

40 CFR 721.1230 - Benzene, ethenyl-, ar-bromo derivatives.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzene, ethenyl-, ar-bromo... Specific Chemical Substances § 721.1230 Benzene, ethenyl-, ar-bromo derivatives. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, ethenyl-, ar...

Excited state of protonated benzene and toluene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esteves-López, Natalia; Dedonder-Lardeux, Claude; Jouvet, Christophe, E-mail: Christophe.jouvet@univ-amu.fr

We present photo-fragmentation electronic spectra of the simplest protonated aromatic molecules, protonated benzene and toluene, recorded under medium resolution conditions and compared with the photo-fragmentation spectrum of protonated pyridine. Despite the resolution and cold temperature achieved in the experiment, the electronic spectra of protonated benzene and toluene are structure-less, thus intrinsically broadened. This is in agreement with the large geometrical changes and the fast dynamic toward internal conversion predicted by ab initio calculations for protonated benzene [Rode et al., J. Phys. Chem. A 113, 5865–5873 (2009)].

Studies on the mechanism of benzene toxicity.

PubMed Central

Snyder, R; Dimitriadis, E; Guy, R; Hu, P; Cooper, K; Bauer, H; Witz, G; Goldstein, B D

1989-01-01

Using the 59Fe uptake method of Lee et al. it was shown that erythropoiesis in female mice was inhibited following IP administration of benzene, hydroquinone, p-benzoquinone, and muconaldehyde. Toluene protected against the effects of benzene. Coadministration of phenol plus either hydroquinone or catechol resulted in greatly increased toxicity. The combination of metabolites most effective in reducing iron uptake was hydroquinone plus muconaldehyde. We have also shown that treating animals with benzene leads to the formation of adducts of bone marrow DNA as measured by the 32P-postlabeling technique. PMID:2792049

Spatial variability in levels of benzene, formaldehyde, and total benzene, toluene, ethylbenzene and xylenes in New York City: a land-use regression study.

PubMed

Kheirbek, Iyad; Johnson, Sarah; Ross, Zev; Pezeshki, Grant; Ito, Kazuhiko; Eisl, Holger; Matte, Thomas

2012-07-31

to common toxic volatile organic compounds in New York City. Land-use regression models were successfully developed for benzene, formaldehyde, and total BTEX using spatial indicators of on-road vehicle emissions and emissions from stationary sources. These estimates will improve the understanding of health effects of individual pollutants in complex urban pollutant mixtures and inform local air quality improvement efforts that reduce disparities in exposure.

High level theoretical study of benzene-halide adducts: the importance of C-H-anion hydrogen bonding.

PubMed

Coletti, Cecilia; Re, Nazzareno

2009-02-26

High level ab initio calculations were performed on the interaction of halide anions (F(-), Cl(-), Br(-), and I(-)) to benzene. For these systems recent experimental and theoretical data are rather scarce, in spite of their growingly acknowledged importance for binding in complex biological systems. We have thus explored the complete basis set limit and the effect of counterpoise basis set superposition error corrections on the minimum geometries and energies of benzene-halide adducts in their possible interaction modes. The binding energy and enthalpy values (ranging from -15.3 kcal/mol for fluoride to -6.1 kcal/mol for iodide) show that the hydrogen bonding occurring in these complexes cannot be described as a weak interaction. We have furthermore investigated the topology of the minima and of other selected sections of the potential energy surface, so to gain further insight on the nature of the halide-benzene interaction. In particular, the geometry corresponding to the C(6v) symmetry, although being overall repulsive, has displayed the unprecedented presence of a small flex (a minimum in C(6v) symmetry) with interaction energy close to zero or slightly attractive.

The nature of cation-pi binding: interactions between tetramethylammonium ion and benzene in aqueous solution.

PubMed Central

Gao, J; Chou, L W; Auerbach, A

1993-01-01

A combined quantum mechanical and molecular mechanical Monte Carlo simulation method was used to determine the free energy of binding between tetramethylammonium ion (TMA+) and benzene in water. The computed free energy as a function of distance (the potential of mean force) has two minima that represent contact and solvent-separated complexes. These species are separated by a broad barrier of about 3 kJ/mol. The results are in good accord with experimental data and suggest that TMA+ binds to benzene more favorably than to chloride ion, with an association constant of about 0.8 M-1. Images FIGURE 2 PMID:8369448

Validated spectroflurimetric determination of some H1 receptor antagonist drugs in pharmaceutical preparations through charge transfer complexation.

PubMed

el-Din, Mohie K Sharaf; Ibrahim, Fawzia; Eid, Manal I; Wahba, Mary E K

2012-01-01

A validated simple, rapid, and selective spectrofluorimetric method was developed for the determination of some antihistaminic H(1) receptor antagonist drugs namely ebastine (EBS), cetirizine dihydrochloride (CTZ), and fexofenadine hydrochloride (FXD). The method is based on the reaction of the cited drugs with some Π acceptors namely p-chloranilic acid (CLA), tetracyanoethylene (TCNE), and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) to give highly fluorescent derivatives. The fluorescence intensity-concentration plots were rectilinear over the concentration ranges of 0.2-3.0, 0.2-2.5 and 0.15-2.0 μg/ml for EBS with CLA, DDQ, and TCNE respectively; 0.5-7.0, 0.5-6.0, and 0.2-4.0 μg/ml for CTZ with the previously mentioned reagents, and 0.2-3.5, 0.5-6.0, and 0.2-3.5 μg/ml for FXD. The factors affecting the formation of the reaction products were carefully studied and optimized. The method was applied for the determination of the studied drugs in their dosage forms. The results obtained were in good agreement with those obtained by the comparison methods. Reactions Stoichiometries of the complexes formed between the studied drugs and Π acceptors were defined by the Job's method of the continuous variation and found in 1:1 in all cases.

40 CFR 721.10028 - Disubstituted benzene metal salts (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Disubstituted benzene metal salts... Specific Chemical Substances § 721.10028 Disubstituted benzene metal salts (generic). (a) Chemical... as disubstituted benzene metal salts (PMNs P-01-901 and P-01-902) are subject to reporting under this...

40 CFR 721.10028 - Disubstituted benzene metal salts (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Disubstituted benzene metal salts... Specific Chemical Substances § 721.10028 Disubstituted benzene metal salts (generic). (a) Chemical... as disubstituted benzene metal salts (PMNs P-01-901 and P-01-902) are subject to reporting under this...

40 CFR 721.10028 - Disubstituted benzene metal salts (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Disubstituted benzene metal salts... Specific Chemical Substances § 721.10028 Disubstituted benzene metal salts (generic). (a) Chemical... as disubstituted benzene metal salts (PMNs P-01-901 and P-01-902) are subject to reporting under this...

40 CFR 721.10028 - Disubstituted benzene metal salts (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Disubstituted benzene metal salts... Specific Chemical Substances § 721.10028 Disubstituted benzene metal salts (generic). (a) Chemical... as disubstituted benzene metal salts (PMNs P-01-901 and P-01-902) are subject to reporting under this...

40 CFR 721.10028 - Disubstituted benzene metal salts (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Disubstituted benzene metal salts... Specific Chemical Substances § 721.10028 Disubstituted benzene metal salts (generic). (a) Chemical... as disubstituted benzene metal salts (PMNs P-01-901 and P-01-902) are subject to reporting under this...

Benzene selectivity in competitive arene hydrogenation: effects of single-site catalyst···acidic oxide surface binding geometry.

PubMed

Gu, Weixing; Stalzer, Madelyn Marie; Nicholas, Christopher P; Bhattacharyya, Alak; Motta, Alessandro; Gallagher, James R; Zhang, Guanghui; Miller, Jeffrey T; Kobayashi, Takeshi; Pruski, Marek; Delferro, Massimiliano; Marks, Tobin J

2015-06-03

Organozirconium complexes are chemisorbed on Brønsted acidic sulfated ZrO2 (ZrS), sulfated Al2O3 (AlS), and ZrO2-WO3 (ZrW). Under mild conditions (25 °C, 1 atm H2), the supported Cp*ZrMe3, Cp*ZrBz3, and Cp*ZrPh3 catalysts are very active for benzene hydrogenation with activities declining with decreasing acidity, ZrS ≫ AlS ≈ ZrW, arguing that more Brønsted acidic oxides (those having weaker corresponding conjugate bases) yield stronger surface organometallic electrophiles and for this reason have higher benzene hydrogenation activity. Benzene selective hydrogenation, a potential approach for carcinogenic benzene removal from gasoline, is probed using benzene/toluene mixtures, and selectivities for benzene hydrogenation vary with catalyst as ZrBz3(+)/ZrS(-), 83% > Cp*ZrMe2(+)/ZrS(-), 80% > Cp*ZrBz2(+)/ZrS(-), 67% > Cp*ZrPh2(+)/ZrS(-), 57%. For Cp*ZrBz2(+)/ZrS(-), which displays the highest benzene hydrogenation activity with moderate selectivity in benzene/toluene mixtures. Other benzene/arene mixtures are examined, and benzene selectivities vary with arene as mesitylene, 99%, > ethylbenzene, 86% > toluene, 67%. Structural and computational studies by solid-state NMR spectroscopy, XAS, and periodic DFT methods applied to supported Cp*ZrMe3 and Cp*ZrBz3 indicate that larger Zr···surface distances are present in more sterically encumbered Cp*ZrBz2(+)/AlS(-) vs Cp*ZrMe2(+)/AlS(-). The combined XAS, solid state NMR, and DFT data argue that the bulky catalyst benzyl groups expand the "cationic" metal center-anionic sulfated oxide surface distances, and this separation/weakened ion-pairing enables the activation/insertion of more sterically encumbered arenes and influences hydrogenation rates and selectivity patterns.

40 CFR 721.10096 - Benzene, 1,4-bis (methoxymethyl)-.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzene, 1,4-bis (methoxymethyl)-. 721... Substances § 721.10096 Benzene, 1,4-bis (methoxymethyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1,4-bis (methoxymethyl)- (PMN P-03...

40 CFR 721.10096 - Benzene, 1,4-bis (methoxymethyl)-.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, 1,4-bis (methoxymethyl)-. 721... Substances § 721.10096 Benzene, 1,4-bis (methoxymethyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1,4-bis (methoxymethyl)- (PMN P-03...

40 CFR 721.10096 - Benzene, 1,4-bis (methoxymethyl)-.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzene, 1,4-bis (methoxymethyl)-. 721... Substances § 721.10096 Benzene, 1,4-bis (methoxymethyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1,4-bis (methoxymethyl)- (PMN P-03...

40 CFR 721.10096 - Benzene, 1,4-bis (methoxymethyl)-.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzene, 1,4-bis (methoxymethyl)-. 721... Substances § 721.10096 Benzene, 1,4-bis (methoxymethyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1,4-bis (methoxymethyl)- (PMN P-03...

40 CFR 721.10096 - Benzene, 1,4-bis (methoxymethyl)-.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzene, 1,4-bis (methoxymethyl)-. 721... Substances § 721.10096 Benzene, 1,4-bis (methoxymethyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1,4-bis (methoxymethyl)- (PMN P-03...

Genotoxic effects of occupational exposure to benzene in gasoline station workers

PubMed Central

SALEM, Eman; EL-GARAWANI, Islam; ALLAM, Heba; EL-AAL, Bahiga Abd; HEGAZY, Mofrih

2017-01-01

Benzene, a hazardous component of gasoline, is a genotoxic class I human carcinogen. This study evaluated the genotoxic effects of occupational exposure to benzene in gasoline stations. Genotoxicity of exposure to benzene was assessed in peripheral blood leucocytes of 62 gasoline station workers and compared with an equal numbers of matched controls using total genomic DNA fragmentation, micronucleus test and cell viability test. An ambient air samples were collected and analyzed for Monitoring of benzene, toluene, ethyl benzene and xylene (BTEX) in work environment and control areas. DNA fragmentation, micronucleus and dead cells percent were significantly higher in exposed workers than controls. Level of benzene, Toluene, Ethyl benzene and xylene in the work environment were higher than the control areas and the permissible limits. Gasoline station workers occupationally exposed to benzene are susceptible to genotoxic effects indicated by increased DNA fragmentation, higher frequency of micronucleus and decreased leukocytes viability. PMID:29070767

Genotoxic effects of occupational exposure to benzene in gasoline station workers.

PubMed

Salem, Eman; El-Garawani, Islam; Allam, Heba; El-Aal, Bahiga Abd; Hegazy, Mofrih

2018-04-07

Benzene, a hazardous component of gasoline, is a genotoxic class I human carcinogen. This study evaluated the genotoxic effects of occupational exposure to benzene in gasoline stations. Genotoxicity of exposure to benzene was assessed in peripheral blood leucocytes of 62 gasoline station workers and compared with an equal numbers of matched controls using total genomic DNA fragmentation, micronucleus test and cell viability test. An ambient air samples were collected and analyzed for Monitoring of benzene, toluene, ethyl benzene and xylene (BTEX) in work environment and control areas. DNA fragmentation, micronucleus and dead cells percent were significantly higher in exposed workers than controls. Level of benzene, Toluene, Ethyl benzene and xylene in the work environment were higher than the control areas and the permissible limits. Gasoline station workers occupationally exposed to benzene are susceptible to genotoxic effects indicated by increased DNA fragmentation, higher frequency of micronucleus and decreased leukocytes viability.

Benzene waste operations NESHAP. Waiver guidance document

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-01-01

Subpart FF of 40 CFR Part 61 addresses benzene emissions from waste operations at petroleum refineries, chemical manufacturing plants, coke by-product plants, and waste management units that manage wastes from these facilities. Subpart FF, also known as the benzene waste operations national emission standards for hazardous air pollutants (NESHAP), was amended and published in the Federal Register on January 7, 1993. Facilities unable to comply with the NESHAP by April 7, 1993, may apply for a waiver of compliance for a period that shall not extend beyond January 7, 1995. As a condition of the waiver, facilities will be requiredmore » to mitigate benzene air emissions that result from the delay in compliance with the NESHAP. The document outlines the goals and objectives of the benzene waste NESHAP waiver policy, and provides guidance for preparing, reviewing and evaluating waiver requests.« less

Two-photon absorption properties of cationic 1,4-bis(styryl)benzene derivative and its inclusion complexes with cyclodextrins.

PubMed

Nag, Okhil Kumar; Nayak, Rati Ranjan; Lim, Chang Su; Kim, In Hong; Kyhm, Kwangseuk; Cho, Bong Rae; Woo, Han Young

2010-07-29

Two-photon absorption properties of 1,4-bis{4'-[N,N-bis(6''-trimethylammoniumhexyl)amino]styryl}benzene tetrabromide (C1) and its inclusion complexes (ICs) with cyclodextrins (CDs) have been studied. Upon complexation with CDs, the absorption spectra of C1 showed a slight red shift, whereas the emission spectra showed a blue shift with concomitant increase in the fluorescence quantum efficiency. A Stern-Volmer study using K(3)Fe(CN)(6) as a quencher revealed significant reduction in the photoinduced charge transfer quenching, in accord with the IC formation. Comparison of the spectroscopic results reveals that C1 forms increasingly more stable ICs in the order C1/beta-CD < C1/gamma-CD < C1/(3gamma:beta)-CD (gamma-CD/beta-CD 3:1, mole ratio). Moreover, the two-photon action cross section of C1 increased from 200 GM for C1 to 400 GM for C1/beta-CD, 460 GM for C1/gamma-CD, and 650 GM for C1/(3gamma:beta)-CD, respectively. Furthermore, the two-photon microscopy images of HeLa cells stained with C1 emitted strong two-photon excited fluorescence in the plasma membrane. These results provide a useful guideline for the development of efficient two-photon materials for bioimaging applications.

Oxidation Chemistry of Inorganic Benzene Complexes.

PubMed

Fleischmann, Martin; Dielmann, Fabian; Balázs, Gábor; Scheer, Manfred

2016-10-17

The oxidation of the 28 VE cyclo-E 6 triple-decker complexes [(Cp R Mo) 2 (μ,η 6 :η 6 -E 6 )] (E=P, Cp R =Cp(2 a), Cp*(2 b), Cp Bn (2 c)=C 5 (CH 2 Ph) 5 ; E=As, Cp R =Cp*(3)) by Cu + or Ag + leads to cationic 27 VE complexes that retain their general triple-decker geometry in the solid state. The obtained products have been characterized by cyclic voltammetry (CV), EPR, Evans NMR, multinuclear NMR spectroscopy, MS, and structural analysis by single-crystal X-ray diffraction. The cyclo-E 6 middle decks of the oxidized complexes are distorted to a quinoid (2 a) or bisallylic (2 b, 2 c, 3) geometry. DFT calculations of 2 a, 2 b, and 3 persistently result in the bisallylic distortion as the minimum geometry and show that the oxidation leads to a depopulation of the σ-system of the cyclo-E 6 ligands in 2 a-3. Among the starting complexes, 2 c is reported for the first time including its preparation and full characterization. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Clinical analysis of 43 cases of chronic benzene poisoning.

PubMed

Kuang, Shouren; Liang, Weihui

2005-05-30

Benzene can result in bone marrow suppression. Chronic benzene poisoning (CBP) can be found among workers with excessive benzene exposure. CBP could give the appearance of different types of disorders such as leukopenia, agranulocytosis, anemia, pancytopenia, aplastic anemia (AA), myelodysplastic syndrome (MDS), and leukemia. This paper describes 43 CBP cases with the patients' ages ranging from 18 to 36 years (average: 23 years). Among them, 13 (30%) were male and 30 (70%) were female. Their job titles were furniture maker, shoemaker, industrial painter and metal shop worker. Their work durations ranged from 1.5 to 72 months (average: 14 months). Benzene levels in these workplaces exceeded 30 mg/m3. Ten of the 43 cases (23%) were diagnosed as mild cases of CBP, another 10 (23%) were moderate, and 23 (53%) were severe. Treatment for CBP included the following: cessation of benzene exposure, general supportive therapy, antibiotics, vitamins, corticosteroids, androgens, colony-stimulating factors (G-CSF, GM-CSF), blood component therapy, and traditional Chinese medicine. Thirty-three (77%) of the cases recovered completely, nine (21%) cases improved, and one (2%) died. In general, prognosis of CBP cases is optimistic when appropriate treatment is given. However, a few of the benzene-induced AA cases showed no response to treatment, which raises questions about the traditional view of the pathogenesis of the illness. Furthermore, only a part of the population with the same level of benzene exposure would suffer from the disease. Still, CBP cases with the same benzene exposure level exhibited different extents of severity of the illness. This evidence suggests strongly the existence of individual susceptibility. Detection of the biological markers regarding the individual susceptibility would be valuable for screening workers who are not suitable to be exposed to benzene.

Benzene degradation in a denitrifying biofilm reactor: activity and microbial community composition.

PubMed

van der Waals, Marcelle J; Atashgahi, Siavash; da Rocha, Ulisses Nunes; van der Zaan, Bas M; Smidt, Hauke; Gerritse, Jan

2017-06-01

Benzene is an aromatic compound and harmful for the environment. Biodegradation of benzene can reduce the toxicological risk after accidental or controlled release of this chemical in the environment. In this study, we further characterized an anaerobic continuous biofilm culture grown for more than 14 years on benzene with nitrate as electron acceptor. We determined steady state degradation rates, microbial community composition dynamics in the biofilm, and the initial anaerobic benzene degradation reactions. Benzene was degraded at a rate of 0.15 μmol/mg protein/day and a first-order rate constant of 3.04/day which was fourfold higher than rates reported previously. Bacteria belonging to the Peptococcaceae were found to play an important role in this anaerobic benzene-degrading biofilm culture, but also members of the Anaerolineaceae were predicted to be involved in benzene degradation or benzene metabolite degradation based on Illumina MiSeq analysis of 16S ribosomal RNA genes. Biomass retention in the reactor using a filtration finger resulted in reduction of benzene degradation capacity. Detection of the benzene carboxylase encoding gene, abcA, and benzoic acid in the culture vessel indicated that benzene degradation proceeds through an initial carboxylation step.

Superconductivity in solid benzene molecular crystal.

PubMed

Zhong, Guo-Hua; Yang, Chun-Lei; Chen, Xiao-Jia; Lin, Hai-Qing

2018-06-20

Light-element compounds hold great promise of high critical temperature superconductivity judging from the theoretical perspective. A hydrogen-rich material, benzene, is such a kind of candidate but also an organic compound. A series of first-principles calculations are performed on the electronic structures, dynamics properties, and electron-phonon interactions of solid benzene at high pressures. Benzene is found to be dynamically stable in the pressure range of 180-200 GPa and to exhibit superconductivity with a maximum transition temperature of 20 K at 195 GPa. The phonon modes of carbon atoms are identified to mainly contribute to the electron-phonon interactions driving this superconductivity. The predicted superconductivity in this simplest pristine hydrocarbon shows a common feature in aromatic hydrocarbons and also makes it a bridge to organic and hydrogen-rich superconductors.

Superconductivity in solid benzene molecular crystal

NASA Astrophysics Data System (ADS)

Zhong, Guo-Hua; Yang, Chun-Lei; Chen, Xiao-Jia; Lin, Hai-Qing

2018-06-01

Light-element compounds hold great promise of high critical temperature superconductivity judging from the theoretical perspective. A hydrogen-rich material, benzene, is such a kind of candidate but also an organic compound. A series of first-principles calculations are performed on the electronic structures, dynamics properties, and electron–phonon interactions of solid benzene at high pressures. Benzene is found to be dynamically stable in the pressure range of 180–200 GPa and to exhibit superconductivity with a maximum transition temperature of 20 K at 195 GPa. The phonon modes of carbon atoms are identified to mainly contribute to the electron–phonon interactions driving this superconductivity. The predicted superconductivity in this simplest pristine hydrocarbon shows a common feature in aromatic hydrocarbons and also makes it a bridge to organic and hydrogen-rich superconductors.

Single-molecule conductance through multiple π-π-stacked benzene rings determined with direct electrode-to-benzene ring connections.

PubMed

Schneebeli, Severin T; Kamenetska, Maria; Cheng, Zhanling; Skouta, Rachid; Friesner, Richard A; Venkataraman, Latha; Breslow, Ronald

2011-02-23

Understanding electron transport across π-π-stacked systems will help to answer fundamental questions about biochemical redox processes and benefit the design of new materials and molecular devices. Herein we employed the STM break-junction technique to measure the single-molecule conductance of multiple π-π-stacked aromatic rings. We studied electron transport through up to four stacked benzene rings held together in an eclipsed fashion via a paracyclophane scaffold. We found that the strained hydrocarbons studied herein couple directly to gold electrodes during the measurements; hence, we did not require any heteroatom binding groups as electrical contacts. Density functional theory-based calculations suggest that the gold atoms of the electrodes bind to two neighboring carbon atoms of the outermost cyclophane benzene rings in η(2) fashion. Our measurements show an exponential decay of the conductance with an increasing number of stacked benzene rings, indicating a nonresonant tunneling mechanism. Furthermore, STM tip-substrate displacement data provide additional evidence that the electrodes bind to the outermost benzene rings of the π-π-stacked molecular wires.

Increased leukemia-associated gene expression in benzene-exposed workers

PubMed Central

Li, Keqiu; Jing, Yaqing; Yang, Caihong; Liu, Shasha; Zhao, Yuxia; He, Xiaobo; Li, Fei; Han, Jiayi; Li, Guang

2014-01-01

Long-term exposure to benzene causes several adverse health effects, including an increased risk of acute myeloid leukemia. This study was to identify genetic alternations involved in pathogenesis of leukemia in benzene-exposed workers without clinical symptoms of leukemia. This study included 33 shoe-factory workers exposed to benzene at levels from 1 ppm to 10 ppm. These workers were divided into 3 groups based on the benzene exposure time, 1- < 7, 7- < 12, and 12- < 24 years. 17 individuals without benzene exposure history were recruited as controls. Cytogenetic analysis using Affymetrix Cytogenetics Array found copy-number variations (CNVs) in several chromosomes of benzene-exposed workers. Expression of targeted genes in these altered chromosomes, NOTCH1 and BSG, which play roles in leukemia pathogenesis, was further examined using real-time PCR. The NOTCH1 mRNA level was significantly increased in all 3 groups of workers, and the NOTCH1 mRNA level in the 12- < 24 years group was significantly higher than that in 1- < 7 and 7- < 12 years groups. Compared to the controls, the BSG mRNA level was significantly increased in 7- < 12 and 12- < 24 years groups, but not in the 1- < 7 years group. These results suggest that CNVs and leukemia-related gene expression might play roles in leukemia development in benzene-exposed workers. PMID:24993241

Environmental and occupational exposure to benzene in Thailand.

PubMed

Navasumrit, Panida; Chanvaivit, Sirirat; Intarasunanont, Pornpat; Arayasiri, Manaswee; Lauhareungpanya, Narumon; Parnlob, Varaporn; Settachan, Daam; Ruchirawat, Mathuros

2005-05-30

Exposure to benzene in air is a concern in Thailand, particularly since it was observed that the incidence of blood-related cancers, such as leukemia and lymphoma, has increased in the past few decades. In Bangkok, the mean atmospheric levels of benzene on main roads and in schools were 33.71 and 8.25 ppb, respectively, while in gasoline service stations and petrochemical factories the mean ambient levels were 64.78 and 66.24 ppb, respectively. Cloth vendors (22.61 ppb) and grilled-meat vendors (28.19 ppb) working on the roadsides were exposed to significantly higher levels of benzene than the control group (12.95 ppb; p<0.05). Bangkok school children (5.50 ppb) were exposed to significantly higher levels of benzene than provincial school children (2.54 ppb; p<0.01). Factory workers (73.55 ppb) and gasoline service attendants (121.67 ppb) were exposed to significantly higher levels of benzene than control workers (4.77 ppb; p<0.001). In accordance with the increased benzene exposures, levels of urinary trans,trans-muconic acid (MA) were significantly increased in all benzene-exposed groups. In school children, the levels of MA were relatively high, taking into account the much lower level of exposure. Blood benzene levels were also significantly increased in Bangkok school children (77.97 ppt; p<0.01), gasoline service attendants (641.84 ppt; p<0.05) and factory workers (572.61 ppt; p<0.001), when compared with the respective controls. DNA damage, determined as DNA strand breaks, was found to be elevated in gasoline service attendants, petrochemical factory workers, and Bangkok school children (p<0.001). The cytogenetic challenge assay, which measures DNA repair capacity, showed varying levels of significant increases in the numbers of dicentrics and deletions in gasoline service attendants, petrochemical factory workers and Bangkok school children, indicating a decrease in DNA repair capacity in these subjects.

Benzene inhalation effects upon tetanus antitoxin. Responses and leukemogenesis in mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stoner, R D; Drew, R T; Bernstein, D M

1980-01-01

The effects of inhaled benzene on primary and secondary antibody responses and the incidence of leukemia in mice are reported. Young adult mice were given 5, 12, or 22 exposures to 400 ppM benzene for 6 hrs/day 5 days/week. After the exposure periods, the mice were immunized with absorbed tetanus toxoid (APTT) and/or fluid tetanus toxid (FTT). Exposure to benzene increasingly suppressed primary antibody responses to both antigens. Secondary antibody responses to FTT were nearly normal in animals given 10, 15, or 20 exposures to 400 ppM benzene. Other groups of mice were exposed to either 200 ppM or 50more » ppM benzene. Primary antibody responses elicited with FTT and/or APTT were nearly normal in all mice exposed to 50 ppM benzene and in mice exposed to 200 ppM benzene for 5 days. However, 10 and 20 exposures to 200 ppM benzene inhibited antibody production. The effects of chronically inhaled 300 ppM benzene on the time of onset and incidence of leukemia in 400 7-month-old female HRS/J mice were also studied. Two genotypes were used; the (hr/hr) hairless mice are leukemia-prone, whereas the (hr/+) haired mice are more resistant to leukemia. The exposure continued for a period of 6 months. Lymphoid, myeloid, and mixed (lymphoid and myeloid) leukemias were observed. Ninety percent of the (hr/hr) mice exposed to benzene died from leukemia as compared with 91% for the (hr/hr) air control group. Eighty-five percent of the (hr/+) mice exposed to benzene died from leukemia as compared with 81% for the (hr/+) air control group. Exposures to 300 ppM benzene did not alter the time of onset or the incidence of leukemia commonly expected in HRS/J mice.« less

Acclimation of aerobic-activated sludge degrading benzene derivatives and co-metabolic degradation activities of trichloroethylene by benzene derivative-grown aerobic sludge.

PubMed

Wang, Shizong; Yang, Qi; Bai, Zhiyong; Wang, Shidong; Wang, Yeyao; Nowak, Karolina M

2015-01-01

The acclimation of aerobic-activated sludge for degradation of benzene derivatives was investigated in batch experiments. Phenol, benzoic acid, toluene, aniline and chlorobenzene were concurrently added to five different bioreactors which contained the aerobic-activated sludge. After the acclimation process ended, the acclimated phenol-, benzoic acid-, toluene-, aniline- and chlorobenzene-grown aerobic-activated sludge were used to explore the co-metabolic degradation activities of trichloroethylene (TCE). Monod equation was employed to simulate the kinetics of co-metabolic degradation of TCE by benzene derivative-grown sludge. At the end of experiments, the mixed microbial communities grown under different conditions were identified. The results showed that the acclimation periods of microorganisms for different benzene derivatives varied. The maximum degradation rates of TCE for phenol-, benzoic acid-, toluene-, aniline- and chlorobenzene-grown aerobic sludge were 0.020, 0.017, 0.016, 0.0089 and 0.0047 mg g SS(-1) h(-1), respectively. The kinetic of TCE degradation in the absence of benzene derivative followed Monod equation well. Also, eight phyla were observed in the acclimated benzene derivative-grown aerobic sludge. Each of benzene derivative-grown aerobic sludge had different microbial community composition. This study can hopefully add new knowledge to the area of TCE co-metabolic by mixed microbial communities, and further the understanding on the function and applicability of aerobic-activated sludge.

Low-dose metabolism of benzene in humans: science and obfuscation

PubMed Central

Rappaport, Stephen M.

2013-01-01

Benzene is a ubiquitous air pollutant that causes human leukemia and hematotoxic effects. Although the mechanism by which benzene causes toxicity is unclear, metabolism is required. A series of articles by Kim et al. used air and biomonitoring data from workers in Tianjin, China, to investigate the dose-specific metabolism (DSM) of benzene over a wide range of air concentrations (0.03–88.9 p.p.m.). Kim et al. concluded that DSM of benzene is greatest at air concentrations <1 p.p.m. This provocative finding motivated the American Petroleum Institute to fund a study by Price et al. to reanalyze the original data. Although their formal ‘reanalysis’ reproduced Kim’s finding of enhanced DSM at sub-p.p.m. benzene concentrations, Price et al. argued that Kim’s methods were inappropriate for assigning benzene exposures to low exposed subjects (based on measurements of urinary benzene) and for adjusting background levels of metabolites (based on median values from the 60 lowest exposed subjects). Price et al. then performed uncertainty analyses under alternative approaches, which led them to conclude that ‘… the Tianjin data appear to be too uncertain to support any conclusions …’ regarding the DSM of benzene. They also argued that the apparent low-dose metabolism of benzene could be explained by ‘lung clearance.’ In addressing these criticisms, we show that the methods and arguments presented by Price et al. are scientifically unsound and that their results are unreliable. PMID:23222815

Temporal Variation in the Association between Benzene and Leukemia Mortality

PubMed Central

Richardson, David B.

2008-01-01

Background Benzene is a human carcinogen. Exposure to benzene occurs in occupational and environmental settings. Objective I evaluated variation in benzene-related leukemia with age at exposure and time since exposure. Methods I evaluated data from a cohort of 1,845 rubber hydrochloride workers. Benzene exposure–leukemia mortality trends were estimated by applying proportional hazards regression methods. Temporal variation in the impact of benzene on leukemia rates was assessed via exposure time windows and fitting of a multistage cancer model. Results The association between leukemia mortality and benzene exposures was of greatest magnitude in the 10 years immediately after exposure [relative rate (RR) at 10 ppm-years = 1.19; 95% confidence interval (CI), 1.10–1.29]; the association was of smaller magnitude in the period 10 to < 20 years after exposure (RR at 10 ppm-years = 1.05; 95% CI, 0.97–1.13); and there was no evidence of association ≥ 20 years after exposure. Leukemia was more strongly associated with benzene exposures accrued at ≥ 45 years of age (RR at 10 ppm-years = 1.11; 95% CI, 1.04–1.17) than with exposures accrued at younger ages (RR at 10 ppm-years = 1.01; 95% CI, 0.92–1.09). Jointly, these temporal effects can be efficiently modeled as a multistage process in which benzene exposure affects the penultimate stage in disease induction. Conclusions Further attention should be given to evaluating the susceptibility of older workers to benzene-induced leukemia. PMID:18335105

[Epidemiological study of cytopenia among benzene-exposed workers and its influential factors].

PubMed

Peng, Juan-juan; Liu, Mei-xia; Yang, Feng; Guo, Wei-wei; Zhuang, Ran; Jia, Xian-dong

2013-03-01

To evaluate the benzene exposure level and cytopenia among the benzene exposed workers in Shanghai, China and to analyze the influential factors for the health of benzene-exposed workers. A total of 3314 benzene-exposed workers, who were from 85 benzene-related enterprises selected by stratified random sampling based on enterprise sizes and industries, were included in the study. The time-weighted average (TWA) concentration of benzene in each workshop was measured by individual sampling and fixed point sampling, and the benzene exposure level in workshop was evaluated accordingly. The occupational health examination results and health status of benzene-exposed workers were collected. The median of TW A concentrations of benzene was 0.3 mg/m3. The TWA concentrations measured at 7 ( 1.4%) of the 504 sampling points were above the safety limit. Of the 7 points, 3 were from large enterprises, 2 from medium enterprises, and 2 from small enterprises; 3 were from shipbuilding industry, 1 from chemical industry, and 3 from light industry. Of the 3314 benzene-exposed workers, 451 ( 13.6%) had cytopenia, including 339 males ( 339/2548, 13.3%) and 112 females ( 112/766, 14.6% ). There were significant differences in the incidence rates of leukopenia and neutropenia among the benzene-exposed workers of different sexes and ages (P<0.05); there were significant differences in the incidence rate of cytopenia among the benzene-exposed workers of different ages and working years ( P<0.05 ); there were significant differences in the incidence of neutropenia among the benzene exposed workers of different working years ( P<0.05). Monitoring and intervention measures should be enhanced to protect the benzene-exposed workers in the large enterprises in shipbuilding industry and medium and private enterprises in chemical industry from occupational hazards.

40 CFR 80.1290 - How are standard benzene credits generated?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 17 2012-07-01 2012-07-01 false How are standard benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1290 How are standard benzene credits generated? (a) The standard credit averaging...

40 CFR 721.1240 - Benzene, (2-bromoethyl)-, ar-bromo derivatives.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzene, (2-bromoethyl)-, ar-bromo... Specific Chemical Substances § 721.1240 Benzene, (2-bromoethyl)-, ar-bromo derivatives. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene...

40 CFR 80.1290 - How are standard benzene credits generated?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 16 2011-07-01 2011-07-01 false How are standard benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1290 How are standard benzene credits generated? (a) The standard credit averaging...

40 CFR 721.1240 - Benzene, (2-bromoethyl)-, ar-bromo derivatives.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzene, (2-bromoethyl)-, ar-bromo... Specific Chemical Substances § 721.1240 Benzene, (2-bromoethyl)-, ar-bromo derivatives. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene...

40 CFR 721.1240 - Benzene, (2-bromoethyl)-, ar-bromo derivatives.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzene, (2-bromoethyl)-, ar-bromo... Specific Chemical Substances § 721.1240 Benzene, (2-bromoethyl)-, ar-bromo derivatives. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene...

40 CFR 80.1290 - How are standard benzene credits generated?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 17 2014-07-01 2014-07-01 false How are standard benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1290 How are standard benzene credits generated? (a) The standard credit averaging...

40 CFR 721.1240 - Benzene, (2-bromoethyl)-, ar-bromo derivatives.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzene, (2-bromoethyl)-, ar-bromo... Specific Chemical Substances § 721.1240 Benzene, (2-bromoethyl)-, ar-bromo derivatives. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene...

40 CFR 80.1290 - How are standard benzene credits generated?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false How are standard benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1290 How are standard benzene credits generated? (a) The standard credit averaging...

40 CFR 80.1290 - How are standard benzene credits generated?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 17 2013-07-01 2013-07-01 false How are standard benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1290 How are standard benzene credits generated? (a) The standard credit averaging...

40 CFR 721.1240 - Benzene, (2-bromoethyl)-, ar-bromo derivatives.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, (2-bromoethyl)-, ar-bromo... Specific Chemical Substances § 721.1240 Benzene, (2-bromoethyl)-, ar-bromo derivatives. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene...

Velocity-dependent emission factors of benzene, toluene and C 2-benzenes of a passenger car equipped with and without a regulated 3-way catalyst

NASA Astrophysics Data System (ADS)

Heeb, Norbert V.; Forss, Anna-Maria; Bach, Christian; Mattrel, Peter

Time-resolved chemical ionization mass spectrometry (CI-MS) has been used to investigate the velocity-dependent emission factors for benzene, toluene, the C 2-benzenes (xylenes and ethyl benzene) and nitrogen monoxide of a gasoline-driven passenger car (1.4 l, model year 1995) driven with or without catalytic exhaust gas treatment. A set of seven different driving cycles - including the European Driving Cycle (EDC), the US Urban (FTP 75) and the Highway driving cycles - with a total driving time of 12,000 s have been studied. From the obtained emission data, two sets of 15,300 and 17,200 data points which represent transient driving in the velocity range of 0-150 km h -1 and in an acceleration window of -2-3 m s -2 were explored to gain velocity-dependent emission factors. The passenger car, equipped with a regulated rhodium-platinum based three-way catalyst, showed optimal conversion efficiency (>95%) for benzene in the velocity range of 60-120 km h -1. The conversion of benzene was reduced (<80%) when driving below 50 km h -1 and the BTXE emissions significantly increased when driven at higher speed and engine load (>130 km h -1). Whereas the conversion efficiency for the class of C 2-benzenes was reduced to 10%, no net conversion could be found for toluene and benzene when driven above 130 km h -1. In contrast, the benzene and toluene emissions exceeded those of the untreated exhaust gas in the velocity range of 130-150 km h -1 by 50-92% and by 10-34%, respectively. Thus, benzene and toluene were formed across the examined three-way catalyst if the engine is operated for an extended time in a fuel-rich mode (lambda<1).

Biomonitoring of gasoline station attendants exposed to benzene: Effect of gender.

PubMed

Moro, Angela M; Brucker, Natália; Charão, Mariele F; Baierle, Marília; Sauer, Elisa; Goethel, Gabriela; Barth, Anelise; Nascimento, Sabrina N; Gauer, Bruna; Durgante, Juliano; Amaral, Beatriz S; Neto, Francisco R A; Gioda, Adriana; Garcia, Solange C

2017-01-01

Women are employed in increasing numbers as gasoline station attendants, a work category with risk of exposure to benzene. We have assessed the effect of gender on biomarkers of occupational benzene exposure. Gasoline station attendants (20 men and 20 women) and 40 control individuals (20 men and 20 women) with no history of occupational benzene exposure were evaluated. Benzene exposure was monitoring by environmental and biological measurements. Urinary trans,trans-muconic acid levels, well-known genetic and hematological alterations linked to benzene exposure, and non-cancer effects on the immune, hepatic, and renal systems were investigated. Our results suggest a potential effect of gender on some effects of occupational benzene exposure, particularly the hematological parameters and trans,trans-muconic acid levels. Despite limitations of our study, our findings provide important considerations about occupational exposure of women to benzene and may contribute to the development of occupational protection standards. Copyright © 2016 Elsevier B.V. All rights reserved.

40 CFR 80.1275 - How are early benzene credits generated?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 16 2011-07-01 2011-07-01 false How are early benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1275 How are early benzene credits generated? (a) For each averaging period per...

40 CFR 80.1275 - How are early benzene credits generated?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 17 2013-07-01 2013-07-01 false How are early benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1275 How are early benzene credits generated? (a) For each averaging period per...

40 CFR 80.1275 - How are early benzene credits generated?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 17 2012-07-01 2012-07-01 false How are early benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1275 How are early benzene credits generated? (a) For each averaging period per...

40 CFR 80.1275 - How are early benzene credits generated?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false How are early benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1275 How are early benzene credits generated? (a) For each averaging period per...

40 CFR 80.1275 - How are early benzene credits generated?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 17 2014-07-01 2014-07-01 false How are early benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1275 How are early benzene credits generated? (a) For each averaging period per...

Biological monitoring of workers exposed to benzene in the coke oven industry.

PubMed Central

Drummond, L; Luck, R; Afacan, A S; Wilson, H K

1988-01-01

Workers in the coke oven industry are potentially exposed to low concentrations of benzene. There is a need to establish a well validated biological monitoring procedure for low level benzene exposure. The use of breath and blood benzene and urinary phenol has been explored in conjunction with personal monitoring data. At exposures of about 1 ppm benzene, urinary phenol is of no value as an indicator of uptake/exposure. Benzene in blood was measured by head space gas chromatography but the concentrations were only just above the detection limit. The determination of breath benzene collected before the next shift is non-specific in the case of smokers. The most useful monitor at low concentrations appears to be breath benzene measured at the end-of-shift. PMID:3378002

Benzene selectivity in competitive arene hydrogenation: Effects of single-site catalyst···acidic oxide surface binding geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, Weixing; Stalzer, Madelyn Marie; Nicholas, Christopher P.

Organozirconium complexes are chemisorbed on Brønsted acidic sulfated ZrO 2 (ZrS), sulfated Al 2O 3 (AlS), and ZrO 2–WO 3 (ZrW). Under mild conditions (25 °C, 1 atm H 2), the supported Cp*ZrMe 3, Cp*ZrBz 3, and Cp*ZrPh 3 catalysts are very active for benzene hydrogenation with activities declining with decreasing acidity, ZrS >> AlS ≈ ZrW, arguing that more Brønsted acidic oxides (those having weaker corresponding conjugate bases) yield stronger surface organometallic electrophiles and for this reason have higher benzene hydrogenation activity. Benzene selective hydrogenation, a potential approach for carcinogenic benzene removal from gasoline, is probed using benzene/toluene mixtures,more » and selectivities for benzene hydrogenation vary with catalyst as ZrBz 3 +/ZrS –, 83% > Cp*ZrMe 2 +/ZrS –, 80% > Cp*ZrBz 2 +/ZrS –, 67% > Cp*ZrPh 2 +/ZrS –, 57%. For Cp*ZrBz 2+/ZrS –, which displays the highest benzene hydrogenation activity with moderate selectivity in benzene/toluene mixtures. Other benzene/arene mixtures are examined, and benzene selectivities vary with arene as mesitylene, 99%, > ethylbenzene, 86% > toluene, 67%. Structural and computational studies by solid-state NMR spectroscopy, XAS, and periodic DFT methods applied to supported Cp*ZrMe 3 and Cp*ZrBz 3 indicate that larger Zr···surface distances are present in more sterically encumbered Cp*ZrBz 2 +/AlS – vs Cp*ZrMe 2 +/AlS –. Furthermore, the combined XAS, solid state NMR, and DFT data argue that the bulky catalyst benzyl groups expand the “cationic” metal center–anionic sulfated oxide surface distances, and this separation/weakened ion-pairing enables the activation/insertion of more sterically encumbered arenes and influences hydrogenation rates and selectivity patterns.« less

Benzene selectivity in competitive arene hydrogenation: Effects of single-site catalyst···acidic oxide surface binding geometry

DOE PAGES

Gu, Weixing; Stalzer, Madelyn Marie; Nicholas, Christopher P.; ...

2015-04-17

Organozirconium complexes are chemisorbed on Brønsted acidic sulfated ZrO 2 (ZrS), sulfated Al 2O 3 (AlS), and ZrO 2–WO 3 (ZrW). Under mild conditions (25 °C, 1 atm H 2), the supported Cp*ZrMe 3, Cp*ZrBz 3, and Cp*ZrPh 3 catalysts are very active for benzene hydrogenation with activities declining with decreasing acidity, ZrS >> AlS ≈ ZrW, arguing that more Brønsted acidic oxides (those having weaker corresponding conjugate bases) yield stronger surface organometallic electrophiles and for this reason have higher benzene hydrogenation activity. Benzene selective hydrogenation, a potential approach for carcinogenic benzene removal from gasoline, is probed using benzene/toluene mixtures,more » and selectivities for benzene hydrogenation vary with catalyst as ZrBz 3 +/ZrS –, 83% > Cp*ZrMe 2 +/ZrS –, 80% > Cp*ZrBz 2 +/ZrS –, 67% > Cp*ZrPh 2 +/ZrS –, 57%. For Cp*ZrBz 2+/ZrS –, which displays the highest benzene hydrogenation activity with moderate selectivity in benzene/toluene mixtures. Other benzene/arene mixtures are examined, and benzene selectivities vary with arene as mesitylene, 99%, > ethylbenzene, 86% > toluene, 67%. Structural and computational studies by solid-state NMR spectroscopy, XAS, and periodic DFT methods applied to supported Cp*ZrMe 3 and Cp*ZrBz 3 indicate that larger Zr···surface distances are present in more sterically encumbered Cp*ZrBz 2 +/AlS – vs Cp*ZrMe 2 +/AlS –. Furthermore, the combined XAS, solid state NMR, and DFT data argue that the bulky catalyst benzyl groups expand the “cationic” metal center–anionic sulfated oxide surface distances, and this separation/weakened ion-pairing enables the activation/insertion of more sterically encumbered arenes and influences hydrogenation rates and selectivity patterns.« less

Environmental and biological monitoring of benzene during self-service automobile refueling.

PubMed Central

Egeghy, P P; Tornero-Velez, R; Rappaport, S M

2000-01-01

Although automobile refueling represents the major source of benzene exposure among the nonsmoking public, few data are available regarding such exposures and the associated uptake of benzene. We repeatedly measured benzene exposure and uptake (via benzene in exhaled breath) among 39 self-service customers using self-administered monitoring, a technique rarely used to obtain measurements from the general public (130 sets of measurements were obtained). Benzene exposures averaged 2.9 mg/m(3) (SD = 5.8 mg/m(3); median duration = 3 min) with a range of < 0.076-36 mg/m(3), and postexposure breath levels averaged 160 microg/m(3) (SD = 260 microg/m(3)) with a range of < 3.2-1,400 microg/m(3). Log-transformed exposures and breath levels were significantly correlated (r = 0.77, p < 0.0001). We used mixed-effects statistical models to gauge the relative influences of environmental and subject-specific factors on benzene exposure and breath levels and to investigate the importance of various covariates obtained by questionnaire. Model fitting yielded three significant predictors of benzene exposure, namely, fuel octane grade (p = 0.0011), duration of exposure (p = 0.0054), and season of the year (p = 0.032). Likewise, another model yielded three significant predictors of benzene concentration in breath, specifically, benzene exposure (p = 0.0001), preexposure breath concentration (p = 0.0008), and duration of exposure (p = 0.038). Variability in benzene concentrations was remarkable, with 95% of the estimated values falling within a 274-fold range, and was comprised entirely of the within-person component of variance (representing exposures of the same subject at different times of refueling). The corresponding range for benzene concentrations in breath was 41-fold and was comprised primarily of the within-person variance component (74% of the total variance). Our results indicate that environmental rather than interindividual differences are primarily responsible for

Hexa-μ-chlorido-hexa­chlorido(η6-hexa­methyl­benzene)trialuminium(III)lanthanum(III) benzene solvate

PubMed Central

Filatov, Alexander S.; Gifford, Sarah N.; Kumar, D. Krishna; Petrukhina, Marina A.

2009-01-01

In the title compound, [Al3LaCl12(C12H18)]·C6H6, all mol­ecules are located on a mirror plane. Three chloridoaluminate groups and a hexa­methyl­benzene mol­ecule are bound to the central lanthanum(III) ion, forming a distorted penta­gonal bipyramid with the η6-coordinated arene located at the apical position. The hexa­methyl­benzene ligand disordered between two orientations in a 1:1 ratio is also involved in parallel-slipped π–π stacking inter­molecular inter­actions with a benzene solvent mol­ecule [centroid–centroid distance 3.612 (4) Å]. PMID:21582071

Residual toxicity after biodegradation: interactions among benzene, toluene, and chloroform.

PubMed

da Silva Nunes-Halldorson, Vânia; Steiner, Robert L; Smith, Geoffrey B

2004-02-01

A microbial enrichment originating from a pristine aquifer was found to aerobically biodegrade benzene and toluene, but not chloroform. This enrichment culture was used to study changes in pollutant toxicity as affected by biodegradative activity. Two assays for toxicity were used: (1) a 48-h acute toxicity test using the freshwater invertebrate Ceriodaphnia dubia and (2) microbial biodegradation activity as affected by the presence of mixed pollutants. At 20-ppm concentrations, toluene was significantly more toxic (99% mortality) to C. dubia than benzene (48% mortality) or chloroform (40% mortality). Also at 20-ppm concentrations, but before biodegradation, toluene was significantly more toxic (88% mortality) to C. dubia than benzene (33% mortality). After biodegradation of 98% of toluene and benzene, significant residual toxicity still remained in the bacterial supernatant: toluene-degraded supernatant caused 33% mortality in C. dubia and benzene-degraded supernatant caused 24% mortality. In the second toxicity assay, examining the effect of mixed pollutants on biodegradation activity, the presence of benzene slowed the biodegradation of toluene, but chloroform had no effect on either benzene or toluene biodegradation. Results indicate that significant toxicity remain after biodegradation and that halogenated aliphatic hydrocarbons may have little or no effect on aromatic hydrocarbon biodegradation at sites impacted by mixed pollutants.

MiR-133a regarded as a potential biomarker for benzene toxicity through targeting Caspase-9 to inhibit apoptosis induced by benzene metabolite (1,4-Benzoquinone).

PubMed

Chen, Yujiao; Sun, Pengling; Bai, Wenlin; Gao, Ai

2016-11-15

Benzene is an environmental and industrial chemical which is widely utilized in various applications. Our previous study showed that miR-133a expression was down-regulated in chronic benzene poisoning workers, but the mechanism of miR-133a in benzene-induced hematotoxicity remains unclear. In this population-based study, benzene-exposed group recruited workers whose concentration of air benzene was 3.50±1.60mg/m(3), and control workers who were exposed to 0.06±0.01mg/m(3) air benzene. By comparison, Caspase-9 and Caspase-3 was up-regulated while miR-133a expression decreased in benzene-exposed workers. Pearson correlation analysis showed that miR-133a was reversely correlated with pro-apoptotic gene Caspase-9 in population-based study. Moreover, multiple linear regressions indicated that miR-133a was positively associated with blood cells count. To explore the underlying mechanism of miR-133a in benzene-induced hematotoxicity, AO/EB staining and TEM ultrastructural analysis were conducted to verify the activation of apoptosis in Human Leukemic U937 Cells induced by benzene metabolites (1,4-Benzoquinone, 1,4-BQ), while the mechanism of miR-133a in 1,4-BQ-induced apoptosis was performed using lentivirus vectors transfection. The results demonstrated that 1,4-BQ evidently induced mitochondria-mediated apoptosis and increased pro-apoptotic genes (Caspase-9 and Caspase-3) expression in a dose-dependent manner. The mechanistic study showed 1,4-BQ decreased miR-133a expression and miR-133a over-expression attenuated 1, 4-BQ-caused upregulation of Caspase-9, Caspase-3 and apoptosis. In conclusion, our research suggested that benzene induced hematotoxicity by decreasing miR-133a and caspase-dependent apoptosis which might contribute to the underlying mechanism of miR-133a in benzene-induced hematotoxicity. Copyright © 2016 Elsevier B.V. All rights reserved.

Bis[2-(2-pyridylmethyl­eneamino)benzene­sulfonato-κ3 N,N′,O]cobalt(II) dihydrate

PubMed Central

Huang, Xue-Ren; Ou-Yang, Miao; Yang, Ge-Ge; Meng, Xiu-Jin; Jiang, Yi-Min

2009-01-01

The title complex, [Co(C12H9N2O3S)2]·2H2O, has site symmetry 2 with the CoII cation located on a twofold rotation axis. Two tridentate 2-(2-pyridylmethyl­eneamino)benzene­sulfonate (paba) ligands chelate to the CoII cation in a distorted octa­hedral geometry. The pyridine and benzene rings in the paba ligand are oriented at a dihedral angle of 42.86 (13)°. Inter­molecular O—H⋯O and C—H⋯O hydrogen bonding is present in the crystal structure. PMID:21578190

40 CFR 721.10366 - Benzene, 4-bromo-1,2-dimethyl-.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzene, 4-bromo-1,2-dimethyl-. 721... Substances § 721.10366 Benzene, 4-bromo-1,2-dimethyl-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 4-bromo-1,2-dimethyl-(PMN P-10-76...

40 CFR 721.10366 - Benzene, 4-bromo-1,2-dimethyl-.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzene, 4-bromo-1,2-dimethyl-. 721... Substances § 721.10366 Benzene, 4-bromo-1,2-dimethyl-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 4-bromo-1,2-dimethyl-(PMN P-10-76...

40 CFR 721.10366 - Benzene, 4-bromo-1,2-dimethyl-.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzene, 4-bromo-1,2-dimethyl-. 721... Substances § 721.10366 Benzene, 4-bromo-1,2-dimethyl-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 4-bromo-1,2-dimethyl-(PMN P-10-76...

40 CFR 721.1193 - Benzene, 2-bromo-1,4-dimethoxy-.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzene, 2-bromo-1,4-dimethoxy-. 721... Substances § 721.1193 Benzene, 2-bromo-1,4-dimethoxy-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 2-bromo-1,4-dimethoxy- (PMN P-95...

40 CFR 721.1193 - Benzene, 2-bromo-1,4-dimethoxy-.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzene, 2-bromo-1,4-dimethoxy-. 721... Substances § 721.1193 Benzene, 2-bromo-1,4-dimethoxy-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 2-bromo-1,4-dimethoxy- (PMN P-95...

40 CFR 721.1193 - Benzene, 2-bromo-1,4-dimethoxy-.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzene, 2-bromo-1,4-dimethoxy-. 721... Substances § 721.1193 Benzene, 2-bromo-1,4-dimethoxy-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 2-bromo-1,4-dimethoxy- (PMN P-95...

40 CFR 721.1193 - Benzene, 2-bromo-1,4-dimethoxy-.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzene, 2-bromo-1,4-dimethoxy-. 721... Substances § 721.1193 Benzene, 2-bromo-1,4-dimethoxy-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 2-bromo-1,4-dimethoxy- (PMN P-95...

40 CFR 721.1193 - Benzene, 2-bromo-1,4-dimethoxy-.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, 2-bromo-1,4-dimethoxy-. 721... Substances § 721.1193 Benzene, 2-bromo-1,4-dimethoxy-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 2-bromo-1,4-dimethoxy- (PMN P-95...

Methane, benzene and alkyl benzene cold start emission data of gasoline-driven passenger cars representing the vehicle technology of the last two decades

NASA Astrophysics Data System (ADS)

Heeb, Norbert V.; Forss, Anna-Maria; Saxer, Christian J.; Wilhelm, Patrick

The US urban driving cycle (FTP-75) is widely used to estimate both the emissions under hot engine conditions as well as those associated with the cold start. Applying fast analysis techniques such as chemical ionization mass spectrometry (CI-MS) the warm-up behavior of individual vehicles can be monitored at a time resolution of 1 s. CI-MS has been used to investigate the emissions of methane, benzene and the alkyl benzene class of compounds. The amount of the emissions at cold start influence was deduced from the time-resolved emission data of four gasoline-driven vehicle classes representing the vehicle technology of the last two decades. Overall, the emissions of five EURO-0, 20 EURO-1, 18 EURO-2 and so far of six EURO-3 passenger cars were recorded. The test vehicles were selected from the currently operating Swiss car fleet based on the car sales statistics. The average methane, benzene and alkyl benzene cold start emissions are reported using both, the traditional bag method as well as the regression model. At room temperature a clear reduction of 94%, 81% and 85% was found for the methane, benzene and alkyl benzene cold start emissions from EURO-0 to EURO-3 technology, respectively.

REACTION OF BENZENE OXIDE WITH THIOLS INCLUDING GLUTATHIONE

EPA Science Inventory

This study accounts for the observations that the metabolism of benzene is dominated by the formation of phenol. As demonstrated here, the pathway leading to S-phenylmercapturic acid is necessarily minor on account of the low efficiency of benzene oxide capture by glutathione at ...

Carcinogenic Effects of Benzene: An Update (Draft Report)

EPA Science Inventory

The major issue addressed in this document involves the nature and magnitude of the risk of cancer to humans exposed to low levels of benzene. Occupational studies continue to provide the bulk of evidence of benzenes carcinogenicity. Workers are exposed at much higher levels than...

Dehydrogenation of benzene on Pt(111) surface

NASA Astrophysics Data System (ADS)

Gao, W.; Zheng, W. T.; Jiang, Q.

2008-10-01

The dehydrogenation of benzene on Pt(111) surface is studied by ab initio density functional theory. The minimum energy pathways for benzene dehydrogenation are found with the nudge elastic band method including several factors of the associated barriers, reactive energies, intermediates, and transient states. The results show that there are two possible parallel minimum energy pathways on the Pt(111) surface. Moreover, the tilting angle of the H atom in benzene can be taken as an index for the actual barrier of dehydrogenation. In addition, the properties of dehydrogenation radicals on the Pt(111) surface are explored through their adsorption energy, adsorption geometry, and electronic structure on the surface. The vibrational frequencies of the dehydrogenation radicals derived from the calculations are in agreement with literature data.

Hydrogen bonding in the benzene-ammonia dimer

NASA Technical Reports Server (NTRS)

Rodham, David A.; Suzuki, Sakae; Suenram, Richard D.; Lovas, Frank J.; Dasgupta, Siddharth; Goddard, William A., III; Blake, Geoffrey A.

1993-01-01

High-resolution optical and microwave spectra of the gas-phase benzene-ammonia dimer were obtained, showing that the ammonia molecule resides above the benzene plane and undergoes free, or nearly free, internal rotation. To estimate the binding energy (De) and other global properties of the intermolecular potential, theoretical calculations were performed for the benzene-ammonia dimer, using the Gaussian 92 (Fritsch, 1992) program at the MP2/6-31G** level. The predicted De was found to be at the lowest end of the range commonly accepted for hydrogen bonding and considerably below that of C6H6-H2O, consistent with the gas-phase acidities of ammonia and water. The observed geometry greatly resembles the amino-aromatic interaction found naturally in proteins.

Dehydrogenation of benzene on Pt(111) surface.

PubMed

Gao, W; Zheng, W T; Jiang, Q

2008-10-28

The dehydrogenation of benzene on Pt(111) surface is studied by ab initio density functional theory. The minimum energy pathways for benzene dehydrogenation are found with the nudge elastic band method including several factors of the associated barriers, reactive energies, intermediates, and transient states. The results show that there are two possible parallel minimum energy pathways on the Pt(111) surface. Moreover, the tilting angle of the H atom in benzene can be taken as an index for the actual barrier of dehydrogenation. In addition, the properties of dehydrogenation radicals on the Pt(111) surface are explored through their adsorption energy, adsorption geometry, and electronic structure on the surface. The vibrational frequencies of the dehydrogenation radicals derived from the calculations are in agreement with literature data.

Biodegradation of Benzene by Halophilic and Halotolerant Bacteria under Aerobic Conditions

PubMed Central

A. Nicholson, Carla; Z. Fathepure, Babu

2004-01-01

A highly enriched halophilic culture was established with benzene as the sole carbon source by using a brine soil obtained from an oil production facility in Oklahoma. The enrichment completely degraded benzene, toluene, ethylbenzene, and xylenes within 1 to 2 weeks. Also, [14C]benzene was converted to 14CO2, suggesting the culture's ability to mineralize benzene. Community structure analysis revealed that Marinobacter spp. were the dominant members of the enrichment. PMID:14766609

Biodegradation of benzene by halophilic and halotolerant bacteria under aerobic conditions.

PubMed

Nicholson, Carla A; Fathepure, Babu Z

2004-02-01

A highly enriched halophilic culture was established with benzene as the sole carbon source by using a brine soil obtained from an oil production facility in Oklahoma. The enrichment completely degraded benzene, toluene, ethylbenzene, and xylenes within 1 to 2 weeks. Also, [14C]benzene was converted to 14CO2, suggesting the culture's ability to mineralize benzene. Community structure analysis revealed that Marinobacter spp. were the dominant members of the enrichment.

40 CFR 80.55 - Measurement methods for benzene and 1,3-butadiene.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 17 2013-07-01 2013-07-01 false Measurement methods for benzene and 1... Measurement methods for benzene and 1,3-butadiene. (a) Sampling for benzene and 1,3-butadiene must be... 86.109. (b) Benzene and 1,3-butadiene must be analyzed by gas chromatography. Expected values for...

40 CFR 80.55 - Measurement methods for benzene and 1,3-butadiene.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Measurement methods for benzene and 1... Measurement methods for benzene and 1,3-butadiene. (a) Sampling for benzene and 1,3-butadiene must be... 86.109. (b) Benzene and 1,3-butadiene must be analyzed by gas chromatography. Expected values for...

40 CFR 80.55 - Measurement methods for benzene and 1,3-butadiene.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 17 2012-07-01 2012-07-01 false Measurement methods for benzene and 1... Measurement methods for benzene and 1,3-butadiene. (a) Sampling for benzene and 1,3-butadiene must be... 86.109. (b) Benzene and 1,3-butadiene must be analyzed by gas chromatography. Expected values for...

40 CFR 80.55 - Measurement methods for benzene and 1,3-butadiene.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 16 2011-07-01 2011-07-01 false Measurement methods for benzene and 1... Measurement methods for benzene and 1,3-butadiene. (a) Sampling for benzene and 1,3-butadiene must be... 86.109. (b) Benzene and 1,3-butadiene must be analyzed by gas chromatography. Expected values for...

40 CFR 80.55 - Measurement methods for benzene and 1,3-butadiene.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 17 2014-07-01 2014-07-01 false Measurement methods for benzene and 1... Measurement methods for benzene and 1,3-butadiene. (a) Sampling for benzene and 1,3-butadiene must be... 86.109. (b) Benzene and 1,3-butadiene must be analyzed by gas chromatography. Expected values for...

UV spectral shift of benzene in sub- and supercritical water

NASA Astrophysics Data System (ADS)

Kometani, Noritsugu; Takemiya, Koji; Yonezawa, Yoshiro; Amita, Fujitsugu; Kajimoto, Okitsugu

2004-08-01

UV absorption spectra of benzene have been measured over the wide range of temperature and pressure from the ambient state to the supercritical state ( T = 400 °C and P = 40 MPa). The analysis of the spectral shift of benzene in water relative to that in the gas indicates that at T = 380 and 390 °C the local solvent density around benzene is likely to be depressed below the bulk density for densities near the critical density. It is found that π-hydrogen bond between benzene and water becomes evident with lowering temperature below T = 340 °C.

Catalytic conversion of alcohols to hydrocarbons with low benzene content

DOEpatents

Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

2016-09-06

A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

Catalytic conversion of alcohols to hydrocarbons with low benzene content

DOEpatents

Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

2016-03-08

A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

Formation of Benzene in the Interstellar Medium

NASA Technical Reports Server (NTRS)

Jones, Brant M.; Zhang, Fangtong; Kaiser, Ralf I.; Jamal, Adeel; Mebel, Alexander M.; Cordiner, Martin A.; Charnley, Steven B.; Crim, F. Fleming (Editor)

2010-01-01

Polycyclic aromatic hydrocarbons and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block-the aromatic benzene molecule-has remained elusive for decades. Here we demonstrate in crossed molecular beam experiments combined with electronic structure and statistical calculations that benzene (C6H6) can be synthesized via the barrierless, exoergic reaction of the ethynyl radical and 1,3- butadiene, C2H + H2CCHCHCH2 --> C6H6, + H, under single collision conditions. This reaction portrays the simplest representative of a reaction class in which aromatic molecules with a benzene core can be formed from acyclic precursors via barrierless reactions of ethynyl radicals with substituted 1,3-butadlene molecules. Unique gas-grain astrochemical models imply that this low-temperature route controls the synthesis of the very first aromatic ring from acyclic precursors in cold molecular clouds, such as in the Taurus Molecular Cloud. Rapid, subsequent barrierless reactions of benzene with ethynyl radicals can lead to naphthalene-like structures thus effectively propagating the ethynyl-radical mediated formation of aromatic molecules in the interstellar medium.

40 CFR 721.10621 - Distillation bottoms, alkylated benzene by-product (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... benzene by-product (generic). 721.10621 Section 721.10621 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.10621 Distillation bottoms, alkylated benzene by... substance identified generically as distillation bottoms, alkylated benzene by-product (PMN P-12-196) is...

40 CFR 721.10621 - Distillation bottoms, alkylated benzene by-product (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... benzene by-product (generic). 721.10621 Section 721.10621 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.10621 Distillation bottoms, alkylated benzene by... substance identified generically as distillation bottoms, alkylated benzene by-product (PMN P-12-196) is...

Time-Resolved DNA Stable Isotope Probing Links Desulfobacterales- and Coriobacteriaceae-Related Bacteria to Anaerobic Degradation of Benzene under Methanogenic Conditions

PubMed Central

Noguchi, Mana; Kurisu, Futoshi; Kasuga, Ikuro; Furumai, Hiroaki

2014-01-01

To identify the microorganisms involved in benzene degradation, DNA-stable isotope probing (SIP) with 13C-benzene was applied to a methanogenic benzene-degrading enrichment culture. Pyrosequencing of ribosomal RNA (rRNA) gene sequences revealed that the community structure was highly complex in spite of a 3-year incubation only with benzene. The culture degraded 98% of approximately 1 mM 13C-benzene and mineralized 72% of that within 63 d. The terminal restriction fragment length polymorphism (T-RFLP) profiles of the buoyant density fractions revealed the incorporation of 13C into two phylotypes after 64 d. These two phylotypes were determined to be Desulfobacterales- and Coriobacteriaceae-related bacteria by cloning and sequencing of the 16S rRNA gene in the 13C-labeled DNA abundant fraction. Comparative pyrosequencing analysis of the buoyant density fractions of 12C- and 13C-labeled samples indicated the incorporation of 13C into three bacterial and one archaeal OTUs related to Desulfobacterales, Coriobacteriales, Rhodocyclaceae, and Methanosarcinales. The first two OTUs included the bacteria detected by T-RFLP-cloning-sequencing analysis. Furthermore, time-resolved SIP analysis confirmed that the activity of all these microbes appeared at the earliest stage of degradation. In this methanogenic culture, Desulfobacterales- and Coriobacteriaceae-related bacteria were most likely to be the major benzene degraders. PMID:24909708

40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

Code of Federal Regulations, 2014 CFR

2014-07-01

... average benzene concentration determined? 80.1238 Section 80.1238 Protection of Environment ENVIRONMENTAL... Benzene Gasoline Benzene Requirements § 80.1238 How is a refinery's or importer's average benzene concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or imported...

40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

Code of Federal Regulations, 2010 CFR

2010-07-01

... average benzene concentration determined? 80.1238 Section 80.1238 Protection of Environment ENVIRONMENTAL... Benzene Gasoline Benzene Requirements § 80.1238 How is a refinery's or importer's average benzene concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or imported...

40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

Code of Federal Regulations, 2013 CFR

2013-07-01

... average benzene concentration determined? 80.1238 Section 80.1238 Protection of Environment ENVIRONMENTAL... Benzene Gasoline Benzene Requirements § 80.1238 How is a refinery's or importer's average benzene concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or imported...

40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

Code of Federal Regulations, 2012 CFR

2012-07-01

... average benzene concentration determined? 80.1238 Section 80.1238 Protection of Environment ENVIRONMENTAL... Benzene Gasoline Benzene Requirements § 80.1238 How is a refinery's or importer's average benzene concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or imported...

40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

Code of Federal Regulations, 2011 CFR

2011-07-01

... average benzene concentration determined? 80.1238 Section 80.1238 Protection of Environment ENVIRONMENTAL... Benzene Gasoline Benzene Requirements § 80.1238 How is a refinery's or importer's average benzene concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or imported...

Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes.

PubMed

Mao, Feng; Ong, Say Kee; Gaunt, James A

2015-09-01

Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0×10(-9) to 2.8×10(-9) cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

An analysis of violations of Osha's (1987) occupational exposure to benzene standard.

PubMed

Williams, Pamela R D

2014-01-01

The Occupational Safety and Health Administration (OSHA), which was formed by the Occupational Safety and Health Act of 1970 (OSH Act), establishes enforceable health and safety standards in the workplace and issues violations and penalties for non-compliance with these standards. The purpose of the current study was to evaluate the number and type of violations of the OSHA (1987) Occupational Exposure to Benzene Standard. Violations of the OSHA Hazard Communication Standard (HCS), particularly those that may pertain to specific provisions of the benzene standard, were also assessed. All analyses were based on OSHA inspection data that have been collected since the early 1970s and that are publicly available from the U.S. Department of Labor enforcement website. Analysis of these data shows that fewer than a thousand OSHA violations of the benzene standard have been issued over the last 25+ years. The results for benzene are in contrast to those for some other toxic and hazardous substances that are regulated by OSHA, such as blood-borne pathogens, lead, and asbestos, for which there have been issued tens of thousands of OSHA violations. The number of benzene standard violations also varies by time period, standard provision, industry sector, and other factors. In particular, the greatest number of benzene standard violations occurred during the late 1980s to early/mid 1990s, soon after the 1987 final benzene rule was promulgated. The majority of benzene standard violations also pertain to noncompliance with specific provisions and subprovisions of the standard dealing with initial exposure monitoring requirements, the communication of hazards to employees, and medical surveillance programs. Only a small fraction of HCS violations are attributed, at least in part, to potential benzene hazards in the workplace. In addition, most benzene standard violations are associated with specific industries within the manufacturing sector where benzene or benzene

Treatment of co-mingled benzene, toluene and TCE in groundwater.

PubMed

Chen, Liang; Liu, Yulong; Liu, Fei; Jin, Song

2014-06-30

This work addressed a hypothetical but practical scenario that includes biological oxidation and reductive dechlorination in treating groundwater containing co-mingled plume of trichloroethene (TCE), benzene and toluene. Groundwater immediately downgradient from the commonly used zero-valent iron (ZVI) has shown alkaline pH (up to 10.7). The elevated pH may influence BTEX compounds (i.e., benzene, toluene, ethyl benzene, and xylenes) biodegradation, which could also be inhibited by elevated concentrations of TCE. Data from this work suggests that the inhibition coefficients (IC) value for 100 μg/L and 500 μg/L of TCE on benzene and toluene degradation are 2.1-2.8 at pH 7.9, and 3.5-6.1 at pH 10.5. For a co-mingled plume, it appears to be more effective to reduce TCE by ZVI before addressing benzene and toluene biodegradation. The ample buffering capacity of most groundwater and the adaptation of benzene and toluene-degrading microbes are likely able to eliminate the adverse influence of pH shifts downgradient from a ZVI-PRB. Copyright © 2014 Elsevier B.V. All rights reserved.

Adsorption of benzene, toluene, and xylene by two tetramethylammonium-smectites having different charge densities

USGS Publications Warehouse

Lee, Jiunn-Fwu; Mortland, Max M.; Chiou, Cary T.; Kite, Daniel E.; Boyd, Stephen A.

1990-01-01

A high-charge smectite from Arizona [cation-exchange capacity (CEC) = 120 meq/100 g] and a low-charge smectite from Wyoming (CEC = 90 meq/100 g) were used to prepare homoionic tetramethylammonium (TMA)-clay complexes. The adsorption of benzene, toluene, and o-xylene as vapors by the dry TMA-clays and as solutes from water by the wet TMA-clays was studied. The adsorption of the organic vapors by the dry TMA-smectite samples was strong and apparently consisted of interactions with both the aluminosilicate mineral surfaces and the TMA exchange ions in the interlayers. In the adsorption of organic vapors, the closer packing of TMA ions in the dry high-charge TMA-smectite, compared with the dry low-charge TMA-smectite, resulted in a somewhat higher degree of shape-selective adsorption of benzene, toluene, and xylene. In the presence of water, the adsorption capacities of both samples for the aromatic compounds were significantly reduced, although the uptake of benzene from water by the low-charge TMA-smectite was still substantial. This lower sorption capacity was accompanied by increased shape-selectivity for the aromatic compounds. The reduction in uptake and increased selectivity was much more pronounced for the water-saturated, high-charge TMA-smectite than for the low-charge TMA-smectite. Hydration of the TMA exchange ions and/or the mineral surfaces apparently reduced the accessibility of the aromatic molecules to interlamellar regions. The resulting water-induced sieving effect was greater for the high-charge TMA-smectite due to the higher density of exchanged TMA-ions. The low-charge Wyoming TMA-smectite was a highly effective adsorbent for removing benzene from water and may be useful for purifying benzene-contaminated water.

[Factors affecting benzene diffusion from contaminated soils to the atmosphere and flux characteristics].

PubMed

Du, Ping; Wang, Shi-Jie; Zhao, Huan-Huan; Wu, Bin; Han, Chun-Mei; Fang, Ji-Dun; Li, Hui-Ying; Hosomi, Masaaki; Li, Fa-Sheng

2013-12-01

The influencing factors of benzene diffusion fluxes from sand and black soil to atmosphere were investigated using a flux chamber (30.0 cm x 17.5 cm x 29.0 cm). In this study, the benzene diffusion fluxes were estimated by measuring the benzene concentrations both in the headspace of the chamber and in the soils of different layers. The results indicated that the soil water content played an important role in benzene diffusion fluxes. The diffusion flux showed positive correlation with the initial benzene concentration and the benzene dissolution concentration for both soil types. The changes of air flow rate from 300 to 900 mL x min(-1) and temperature from 20 degrees C to 40 degrees C resulted in increases of the benzene diffusion flux. Our study of benzene diffusion fluxes from contaminated soils will be beneficial for the predicting model, and emergency management and precautions.

Peer Review Comments on the IRIS Assessment of Benzene

EPA Pesticide Factsheets

Attachment to IRIS file for benzene, January 19, 2000, RESPONSE TO THE PEER REVIEW COMMENTS, II. Extrapolation of the Benzene Inhalation Unit Risk Estimate to the Oral Route of Exposure (EPA/NCEA-W-0517, July 1999)

Benzene exposure: An overview of monitoring methods and their findings

PubMed Central

Weisel, Clifford P.

2014-01-01

Benzene has been measured throughout the environment and is commonly emitted in several industrial and transportation settings leading to widespread environmental and occupational exposures. Inhalation is the most common exposure route but benzene rapidly penetrates the skin and can contaminant water and food resulting in dermal and ingestion exposures. While less toxic solvents have been substituted for benzene, it still is a component of petroleum products, including gasoline, and is a trace impurity in industrial products resulting in continued sub to low ppm occupational exposures, though higher exposures exist in small, uncontrolled workshops in developing countries. Emissions from gasoline/petrochemical industry are its main sources to the ambient air, but a person’s total inhalation exposure can be elevated from emissions from cigarettes, consumer products and gasoline powered engines/tools stored in garages attached to homes. Air samples are collected in canisters or on adsorbent with subsequent quantification by gas chromatography. Ambient air concentrations vary from sub-ppb range, low ppb, and tens of ppb in rural/suburban, urban, and source impacted areas, respectively. Short-term environmental exposures of ppm occur during vehicle fueling. Indoor air concentrations of tens of ppb occur in microenvironments containing indoor sources. Occupational and environmental exposures have declined where regulations limit benzene in gasoline (<1%) and cigarette smoking has been banned from public and work places. Similar controls should be implemented worldwide to reduce benzene exposure. Biomarkers of benzene used to estimate exposure and risk include: benzene in breath, blood and urine; its urinary metabolites: phenol, t,t-muconic acid (t,tMA) and S-phenylmercapturic acid (sPMA); and blood protein adducts. The biomarker studies suggest benzene environmental exposures are in the sub to low ppb range though non-benzene sources for urinary metabolites

STABILITY OF HEMOGLOBIN AND ALBUMIN ADDUCTS OF BENZENE OXIDE AND 1,4-BENZOQUINONE AFTER ADMINISTRATION OF BENZENE TO F344 RATS

EPA Science Inventory

The stability of cysteinyl adducts of benzene oxide (BO) and mono-S-substituted cysteinyl adducts of 1,4-benzoquinone (1,4-BQ) was investigated in both hemoglobin (Hb) and albumin (Alb) following administration of a single oral dose of 400 mg [U-14C/13C6]benzene/kg body weight ...

Establishment of a Methanogenic Benzene-Degrading Culture and its Implication in Bioremediation

NASA Astrophysics Data System (ADS)

Qiao, W.; Luo, F.; Bawa, N.; Guo, S.; Ye, S.; Edwards, E.

2017-12-01

Benzene is a known human carcinogen and it is a common pollutant in groundwater, mainly resulting from petrochemical industry. Anaerobic degradation of benzene has significant advantages over aerobic processes for in situ bioremediation. In this study, new methanogenic and sulfate-reducing benzene degrading cultures have been enriched. Microbial community composition was characterized with two other previously established benzene-degrading cultures, and their potential use in bioaugmentation is investigated. In this study, a lab microcosm study was conducted anaerobically with contaminated soil and groundwater from a former chemical plant. Benzene degradation was observed in the presence of co-contaminants and electron donor. Through repetitive amendment of benzene, two enrichment cultures have been developed under sulfate and methanogenic conditions. Results from DNA amplicon sequencing and qPCR analysis revealed that an organism similar to previously described benzene-degrading Deltaproteobacterium has been enriched. The microbial community of this culture was compared with other two methanogenic benzene-degrading enrichment cultures that were derived from an oil refinery and a decommissioned gasoline station, and have been maintained for decades. Deltaproteobacterium ORM2-like microbes were dominate in all enrichment cultures, which brought to light benzene-degrading microbes, ORM2 were enriched under different geological conditions distributed around the world. The relative abundance of methanogens was much lower compared to previously established cultures, although substantial amount of methane was produced. The peripheral organisms also vary. To investigate effectiveness of using ORM2-dominant enrichment cultures in bioremediation, microcosm studies were set up using contaminated materials, and a ORM2-dominating methanogenic benzene-degrading culture was used for bioaugmentation. Results revealed that benzene degradation was speeded up under methanogenic or

"Plug-and-Play" potentials: Investigating quantum effects in (H2)2-Li+-benzene

NASA Astrophysics Data System (ADS)

D'Arcy, Jordan H.; Kolmann, Stephen J.; Jordan, Meredith J. T.

2015-08-01

Quantum and anharmonic effects are investigated in (H2)2-Li+-benzene, a model for hydrogen adsorption in metal-organic frameworks and carbon-based materials, using rigid-body diffusion Monte Carlo (RBDMC) simulations. The potential-energy surface (PES) is calculated as a modified Shepard interpolation of M05-2X/6-311+G(2df,p) electronic structure data. The RBDMC simulations yield zero-point energies (ZPE) and probability density histograms that describe the ground-state nuclear wavefunction. Binding a second H2 molecule to the H2-Li+-benzene complex increases the ZPE of the system by 5.6 kJ mol-1 to 17.6 kJ mol-1. This ZPE is 42% of the total electronic binding energy of (H2)2-Li+-benzene and cannot be neglected. Our best estimate of the 0 K binding enthalpy of the second H2 to H2-Li+-benzene is 7.7 kJ mol-1, compared to 12.4 kJ mol-1 for the first H2 molecule. Anharmonicity is found to be even more important when a second (and subsequent) H2 molecule is adsorbed; use of harmonic ZPEs results in significant error in the 0 K binding enthalpy. Probability density histograms reveal that the two H2 molecules are found at larger distance from the Li+ ion and are more confined in the θ coordinate than in H2-Li+-benzene. They also show that both H2 molecules are delocalized in the azimuthal coordinate, ϕ. That is, adding a second H2 molecule is insufficient to localize the wavefunction in ϕ. Two fragment-based (H2)2-Li+-benzene PESs are developed. These use a modified Shepard interpolation for the Li+-benzene and H2-Li+-benzene fragments, and either modified Shepard interpolation or a cubic spline to model the H2-H2 interaction. Because of the neglect of three-body H2, H2, Li+ terms, both fragment PESs lead to overbinding of the second H2 molecule by 1.5 kJ mol-1. Probability density histograms, however, indicate that the wavefunctions for the two H2 molecules are effectively identical on the "full" and fragment PESs. This suggests that the 1.5 kJ mol-1 error is

"Plug-and-Play" potentials: Investigating quantum effects in (H2)2-Li(+)-benzene.

PubMed

D'Arcy, Jordan H; Kolmann, Stephen J; Jordan, Meredith J T

2015-08-21

Quantum and anharmonic effects are investigated in (H2)2-Li(+)-benzene, a model for hydrogen adsorption in metal-organic frameworks and carbon-based materials, using rigid-body diffusion Monte Carlo (RBDMC) simulations. The potential-energy surface (PES) is calculated as a modified Shepard interpolation of M05-2X/6-311+G(2df,p) electronic structure data. The RBDMC simulations yield zero-point energies (ZPE) and probability density histograms that describe the ground-state nuclear wavefunction. Binding a second H2 molecule to the H2-Li(+)-benzene complex increases the ZPE of the system by 5.6 kJ mol(-1) to 17.6 kJ mol(-1). This ZPE is 42% of the total electronic binding energy of (H2)2-Li(+)-benzene and cannot be neglected. Our best estimate of the 0 K binding enthalpy of the second H2 to H2-Li(+)-benzene is 7.7 kJ mol(-1), compared to 12.4 kJ mol(-1) for the first H2 molecule. Anharmonicity is found to be even more important when a second (and subsequent) H2 molecule is adsorbed; use of harmonic ZPEs results in significant error in the 0 K binding enthalpy. Probability density histograms reveal that the two H2 molecules are found at larger distance from the Li(+) ion and are more confined in the θ coordinate than in H2-Li(+)-benzene. They also show that both H2 molecules are delocalized in the azimuthal coordinate, ϕ. That is, adding a second H2 molecule is insufficient to localize the wavefunction in ϕ. Two fragment-based (H2)2-Li(+)-benzene PESs are developed. These use a modified Shepard interpolation for the Li(+)-benzene and H2-Li(+)-benzene fragments, and either modified Shepard interpolation or a cubic spline to model the H2-H2 interaction. Because of the neglect of three-body H2, H2, Li(+) terms, both fragment PESs lead to overbinding of the second H2 molecule by 1.5 kJ mol(-1). Probability density histograms, however, indicate that the wavefunctions for the two H2 molecules are effectively identical on the "full" and fragment PESs. This suggests that

Cultivating microbial dark matter in benzene-degrading methanogenic consortia.

PubMed

Luo, Fei; Devine, Cheryl E; Edwards, Elizabeth A

2016-09-01

The microbes responsible for anaerobic benzene biodegradation remain poorly characterized. In this study, we identified and quantified microbial populations in a series of 16 distinct methanogenic, benzene-degrading enrichment cultures using a combination of traditional 16S rRNA clone libraries (four cultures), pyrotag 16S rRNA amplicon sequencing (11 cultures), metagenome sequencing (1 culture) and quantitative polymerase chain reaction (qPCR; 12 cultures). An operational taxonomic unit (OTU) from the Deltaproteobacteria designated ORM2 that is only 84% to 86% similar to Syntrophus or Desulfobacterium spp. was consistently identified in all enrichment cultures, and typically comprised more than half of the bacterial sequences. In addition to ORM2, a sequence belonging to Parcubacteria (candidate division OD1) identified from the metagenome data was the only other OTU common to all the cultures surveyed. Culture transfers (1% and 0.1%) were made in the presence and absence of benzene, and the abundance of ORM2, OD1 and other OTUs was tracked over 415 days using qPCR. ORM2 sequence abundance increased only when benzene was present, while the abundance of OD1 and other OTUs increased even in the absence of benzene. Deltaproteobacterium ORM2 is unequivocally the benzene-metabolizing population. This study also hints at laboratory cultivation conditions for a member of the widely distributed yet uncultivated Parcubacteria (OD1). © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Formation of benzene in the interstellar medium

PubMed Central

Jones, Brant M.; Zhang, Fangtong; Kaiser, Ralf I.; Jamal, Adeel; Mebel, Alexander M.; Cordiner, Martin A.; Charnley, Steven B.

2011-01-01

Polycyclic aromatic hydrocarbons and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block—the aromatic benzene molecule—has remained elusive for decades. Here we demonstrate in crossed molecular beam experiments combined with electronic structure and statistical calculations that benzene (C6H6) can be synthesized via the barrierless, exoergic reaction of the ethynyl radical and 1,3-butadiene, C2H + H2CCHCHCH2 → C6H6 + H, under single collision conditions. This reaction portrays the simplest representative of a reaction class in which aromatic molecules with a benzene core can be formed from acyclic precursors via barrierless reactions of ethynyl radicals with substituted 1,3-butadiene molecules. Unique gas-grain astrochemical models imply that this low-temperature route controls the synthesis of the very first aromatic ring from acyclic precursors in cold molecular clouds, such as in the Taurus Molecular Cloud. Rapid, subsequent barrierless reactions of benzene with ethynyl radicals can lead to naphthalene-like structures thus effectively propagating the ethynyl-radical mediated formation of aromatic molecules in the interstellar medium. PMID:21187430

Crystal structures of 4-meth-oxy-N-(4-methyl-phenyl)benzene-sulfonamide and N-(4-fluoro-phenyl)-4-meth-oxy-benzene-sulfonamide.

PubMed

Rodrigues, Vinola Z; Preema, C P; Naveen, S; Lokanath, N K; Suchetan, P A

2015-11-01

Crystal structures of two N-(ar-yl)aryl-sulfonamides, namely, 4-meth-oxy-N-(4-methyl-phen-yl)benzene-sulfonamide, C14H15NO3S, (I), and N-(4-fluoro-phen-yl)-4-meth-oxy-benzene-sulfonamide, C13H12FNO3S, (II), were determined and analyzed. In (I), the benzene-sulfonamide ring is disordered over two orientations, in a 0.516 (7):0.484 (7) ratio, which are inclined to each other at 28.0 (1)°. In (I), the major component of the sulfonyl benzene ring and the aniline ring form a dihedral angle of 63.36 (19)°, while in (II), the planes of the two benzene rings form a dihedral angle of 44.26 (13)°. In the crystal structure of (I), N-H⋯O hydrogen bonds form infinite C(4) chains extended in [010], and inter-molecular C-H⋯πar-yl inter-actions link these chains into layers parallel to the ab plane. The crystal structure of (II) features N-H⋯O hydrogen bonds forming infinite one dimensional C(4) chains along [001]. Further, a pair of C-H⋯O inter-molecular inter-actions consolidate the crystal packing of (II) into a three-dimensional supra-molecular architecture.

[Myelofibrosis in a benzene-exposed cleaning worker].

PubMed

Bausà, Roser; Navarro, Lydia; Cortès-Franch, Imma

Long-term exposure to benzene has been associated with several blood malignancies, including aplastic anemia, myeloproliferative neoplasms, and different leukemias. We present a case of primary myelofibrosis in a 59-year-old woman who worked as a cleaner at a car dealership and automobile mechanic shop. For 25 years, she used gasoline as a degreaser and solvent to clean engine parts, floors and work desks on a daily basis. She was referred by her primary care provider to the Occupational Health Unit of Barcelona to assess whether her illness was work-related. Review of her job history and working conditions revealed chronic exposure to benzene in the absence of adequate preventive measures. An association between benzene exposure and myeloproliferative disease was established, suspicious for an occupational disease. Copyright belongs to the Societat Catalana de Salut Laboral.

Distorted allotropes of bi-benzene: vibronic interactions and electronic excitations

NASA Astrophysics Data System (ADS)

Krasnenko, V.; Boltrushko, V.; Hizhnyakov, V.

2017-05-01

Bi-benzene - chemically bound two benzene molecules in stuck position is studied both analytically and numerically. There are several allotropes of bi-benzene having different geometry. The reason of the existence of sundry distorted structures is the pseudo-Jahn-Teller effect. The parameters of vibronic couplings causing distortions are found. For the calculation of these parameters both, the vibronic coupling of carbon atoms in different C6 rings and the vibronic coupling in the rings are considered. The contribution of the distortion of C6-planes to the latter coupling is also found. The energies of all the electronic states of π-electrons in all bi-benzene allotropes are determined by using the calculated vibronic interaction parameters.

Association between Promoter Methylation of Gene ERCC3 and Benzene Hematotoxicity.

PubMed

Zheng, Min; Lin, Feiliang; Hou, Fenxia; Li, Guilan; Zhu, Caiying; Xu, Peiyu; Xing, Caihong; Wang, Qianfei

2017-08-16

Benzene is a primary industrial chemical and a ubiquitous environmental pollutant. ERCC3 is a key player in nucleotide excision repair. Recent studies suggested that site-specific methylation is a possible mechanism of the transcriptional dysregulation by blocking transcription factors binding. We previously found that the average promoter methylation level of ERCC3 was increased in benzene-exposed workers. In order to test whether specific CpG sites of ERCC3 play an important role in benzene-induced epigenetic changes and whether the specific methylation patterns are associated with benzene hematotoxicity, we analyzed the promoter methylation levels of individual CpG sites, transcription factor binding motif and the correlation between aberrant CpG methylation and hematotoxicity in 76 benzene-exposed workers and 24 unexposed controls in China. Out of all the CpGs analyzed, two CpG units located 43 bp upstream and 99 bp downstream of the transcription start site of ERCC3 (CpG 2-4 and CpG 17-18, respectively), showed the most pronounced increase in methylation levels in benzene-exposed workers, compared with unexposed controls (Mean ± SD: 5.86 ± 2.77% vs. 4.92 ± 1.53%, p = 0.032; 8.45 ± 4.09% vs. 6.79 ± 2.50%, p = 0.024, respectively). Using the JASPAR CORE Database, we found that CpG 2-4 and CpG 17-18 were bound by three putative transcription factors (TFAP2A, E2F4 and MZF1). Furthermore, the methylation levels for CpG 2-4 were correlated negatively with the percentage of neutrophils ( β = -0.676, p = 0.005) in benzene-exposed workers. This study demonstrates that CpG-specific DNA methylation in the ERCC3 promoter region may be involved in benzene-induced epigenetic modification and it may contribute to benzene-induced hematotoxicity.

40 CFR 80.1285 - How does a refiner apply for a benzene baseline?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false How does a refiner apply for a benzene... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1285 How does a refiner apply for a benzene baseline? (a) A benzene baseline...

40 CFR 80.1285 - How does a refiner apply for a benzene baseline?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 17 2012-07-01 2012-07-01 false How does a refiner apply for a benzene... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1285 How does a refiner apply for a benzene baseline? (a) A benzene baseline...

40 CFR 80.1285 - How does a refiner apply for a benzene baseline?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 17 2014-07-01 2014-07-01 false How does a refiner apply for a benzene... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1285 How does a refiner apply for a benzene baseline? (a) A benzene baseline...

40 CFR 80.1285 - How does a refiner apply for a benzene baseline?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 16 2011-07-01 2011-07-01 false How does a refiner apply for a benzene... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1285 How does a refiner apply for a benzene baseline? (a) A benzene baseline...

40 CFR 80.1285 - How does a refiner apply for a benzene baseline?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 17 2013-07-01 2013-07-01 false How does a refiner apply for a benzene... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1285 How does a refiner apply for a benzene baseline? (a) A benzene baseline...

Transformation of toluene and benzene by mixed methanogenic cultures.

PubMed Central

Grbić-Galić, D; Vogel, T M

1987-01-01

The aromatic hydrocarbons toluene and benzene were anaerobically transformed by mixed methanogenic cultures derived from ferulic acid-degrading sewage sludge enrichments. In most experiments, toluene or benzene was the only semicontinuously supplied carbon and energy source in the defined mineral medium. No exogenous electron acceptors other than CO2 were present. The cultures were fed 1.5 to 30 mM unlabeled or 14C-labeled aromatic substrates (ring-labeled toluene and benzene or methyl-labeled toluene). Gas production from unlabeled substrates and 14C activity distribution in products from the labeled substrates were monitored over a period of 60 days. At least 50% of the substrates were converted to CO2 and methane (greater than 60%). A high percentage of 14CO2 was recovered from the methyl group-labeled toluene, suggesting nearly complete conversion of the methyl group to CO2 and not to methane. However, a low percentage of 14CO2 was produced from ring-labeled toluene or from benzene, indicating incomplete conversion of the ring carbon to CO2. Anaerobic transformation pathways for unlabeled toluene and benzene were studied with the help of gas chromatography-mass spectrometry. The intermediates detected are consistent with both toluene and benzene degradation via initial oxidation by ring hydroxylation or methyl oxidation (toluene), which would result in the production of phenol, cresols, or aromatic alcohol. Additional reactions, such as demethylation and ring reduction, are also possible. Tentative transformation sequences based upon the intermediates detected are discussed. PMID:3105454

Infrared identification of the σ-complex of Cl-C6H6 in the reaction of chlorine atom and benzene in solid para-hydrogen.

PubMed

Bahou, Mohammed; Witek, Henryk; Lee, Yuan-Pern

2013-02-21

The reaction of a chlorine atom with benzene (C6H6) is important in organic chemistry, especially in site-selective chlorination reactions, but its product has been a subject of debate for five decades. Previous experimental and theoretical studies provide no concrete conclusion on whether the product is a π- or σ-form of the Cl-C6H6 complex. We took advantage of the diminished cage effect of para-hydrogen (p-H2) to produce Cl in situ to react with C6H6 (or C6D6) upon photolysis of a Cl2/C6H6 (or C6D6)/p-H2 matrix at 3.2 K. The infrared spectrum, showing intense lines at 1430.5, 833.6, 719.8, 617.0, and 577.4 cm(−1), and several weaker ones for Cl-C6H6, and the deuterium shifts of observed new lines unambiguously indicate that the product is a 6-chlorocyclohexadienyl radical, i.e., the σ-complex of Cl-C6H6. Observation of the σ-complex rather than the π-complex indicates that the σ-complex is more stable in solid p-H2 at 3.2 K. The spectral information is crucial for further investigations of the Cl + C6H6 reaction either in the gaseous or solution phase.

Evidence for non-linear metabolism at low benzene exposures? A reanalysis of data.

PubMed

McNally, K; Sams, C; Loizou, G D; Jones, K

2017-12-25

The presence of a high-affinity metabolic pathway for low level benzene exposures of less than one part per million (ppm) has been proposed although a pathway has not been identified. The variation of metabolite molar fractions with increasing air benzene concentrations was suggested as evidence of significantly more efficient benzene metabolism at concentrations <0.1 ppm The evidence for this pathway is predicated on a rich data set from a study of Chinese shoe workers exposed to a wide range of benzene concentrations (not just "low level"). In this work we undertake a further independent re-analysis of this data with a focus on the evidence for an increase in the rate of metabolism of benzene exposures of less than 1 ppm. The analysis dataset consisted of measurements of benzene and toluene from personal air samplers, and measurements of unmetabolised benzene and toluene and five metabolites (phenol hydroquinone, catechol, trans, trans-muconic acid and s-phenylmercapturic acid) from post-shift urine samples for 213 workers with an occupational exposure to benzene (and toluene) and 139 controls. Measurements from control subjects were used to estimate metabolite concentrations resulting from non-occupational sources, including environmental sources of benzene. Data from occupationally exposed subjects were used to estimate metabolite concentrations as a function of benzene exposure. Correction for background (environmental exposure) sources of metabolites was achieved through a comparison of geometric means in occupationally exposed and control populations. The molar fractions of the five metabolites as a function of benzene exposure were computed. A supra-linear relationship between metabolite concentrations and benzene exposure was observed over the range 0.1-10 ppm benzene, however over the range benzene exposures of between 0.1 and 1 ppm only a modest departure from linearity was observed. The molar fractions estimated in this work were near constant over

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Disubstituted benzene ether, polymer... Significant New Uses for Specific Chemical Substances § 721.1580 Disubstituted benzene ether, polymer with... chemical substance generically identified as disubstituted benzene ether, polymer with substituted phenol...

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Disubstituted benzene ether, polymer... Significant New Uses for Specific Chemical Substances § 721.1580 Disubstituted benzene ether, polymer with... chemical substance generically identified as disubstituted benzene ether, polymer with substituted phenol...

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Disubstituted benzene ether, polymer... Significant New Uses for Specific Chemical Substances § 721.1580 Disubstituted benzene ether, polymer with... chemical substance generically identified as disubstituted benzene ether, polymer with substituted phenol...

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Disubstituted benzene ether, polymer... Significant New Uses for Specific Chemical Substances § 721.1580 Disubstituted benzene ether, polymer with... chemical substance generically identified as disubstituted benzene ether, polymer with substituted phenol...

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Disubstituted benzene ether, polymer... Significant New Uses for Specific Chemical Substances § 721.1580 Disubstituted benzene ether, polymer with... chemical substance generically identified as disubstituted benzene ether, polymer with substituted phenol...

Aromaticity of benzene derivatives: an exploration of the Cambridge Structural Database.

PubMed

Majerz, Irena; Dziembowska, Teresa

2018-04-01

The harmonic oscillator model of aromaticity (HOMA) index, one of the most popular aromaticity indices for solid-state benzene rings in the Cambridge Structural Database (CSD), has been analyzed. The histograms of HOMA for benzene, for benzene derivatives with one formyl, nitro, amino or hydroxy group as well as the histograms for the derivatives with two formyl, nitro, amino or hydroxy groups in ortho, meta and para positions were investigated. The majority of the substituted benzene derivatives in the CSD are characterized by a high value of HOMA, indicating fully aromatic character; however, the distribution of the HOMA value from 1 to about 0 indicates decreasing aromaticity down to non-aromatic character. Among the benzene derivatives investigated, a significant decrease in aromaticity can be related to compounds with diamino and dinitro groups in the meta position.

Effects of nitrogenous substituent groups on the benzene dication

NASA Astrophysics Data System (ADS)

Forgy, C. C.; Schlimgen, A. W.; Mazziotti, D. A.

2018-05-01

The benzene dication possesses a pentagonal-pyramidal structure with a hexacoordinated carbon. In contrast, halogenated benzene dications retain a similar structure to their parent molecules. In this work, we report on theoretical studies of the structures of the dications of benzene with nitrogenous substituents. We find that the nitrobenzene dication favours a near ideal pentagonal-pyramidal structure, while the aniline dication favours a flat, hexagonal structure. Reduced-density-matrices methods give predictions in agreement with available ab initio calculations and experiment. These results are also compared with those from the Hartree-Fock method and density functional theory.

The immunotoxicological pattern of subchronic and chronic benzene exposure in rats.

PubMed

Karaulov, Alexander V; Mikhaylova, Irina V; Smolyagin, Alexander I; Boev, Viktor M; Kalogeraki, Alexandra; Tsatsakis, Aristides M; Engin, Ayse Basak

2017-06-05

Exposure to benzene and its inevitable metabolites can result in deleterious effects on human health, including lymphocytopenia, hematotoxicity and cancer. However, the duration of exposure might alter the effects including immune consequences. The aim of this study was to determine whether benzene could modulate lymphocyte proliferation induced by the T cell mitogen concanavalin A, in rats, at different exposure durations. 386 Wistar rats were assigned into control and treatment groups which were subdivided into groups for 45, 90 and 135days for 0,6mL/kg of drinking water mixed benzene treatment. The percentage of CD3+, CD4+, CD8+ spleen lymphocytes was defined using the flow cytometer. Interleukin (IL)-4, IL-6, IL-10 and interferon-gamma, in supernatants of splenocyte cultures stimulated with Concanavalin A, were assessed by enzyme-linked immunosorbent assay (ELISA) technique. The decrease in the total lymphocyte and T cell counts were associated with increased benzene exposure duration. Th2-type cytokine, IL-4 significantly increased, whereas IL-6, CD4+T cells, CD4+/CD8+ ratio and CD3+ T cells decreased. Despite the positive correlation between benzene toxicity and indicated increased immune responses, 45-day exposure to benzene appeared to be the most sensitive time point for evaluating benzene cytotoxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

40 CFR 721.10367 - Hydroxy-aryl, polymer with substituted benzene, cyanate (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... benzene, cyanate (generic). 721.10367 Section 721.10367 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10367 Hydroxy-aryl, polymer with substituted benzene... substance identified generically as hydroxy-aryl, polymer with substituted benzene, cyanate (PMN P-10-83) is...

40 CFR 721.10367 - Hydroxy-aryl, polymer with substituted benzene, cyanate (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... benzene, cyanate (generic). 721.10367 Section 721.10367 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10367 Hydroxy-aryl, polymer with substituted benzene... substance identified generically as hydroxy-aryl, polymer with substituted benzene, cyanate (PMN P-10-83) is...

40 CFR 721.10367 - Hydroxy-aryl, polymer with substituted benzene, cyanate (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... benzene, cyanate (generic). 721.10367 Section 721.10367 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10367 Hydroxy-aryl, polymer with substituted benzene... substance identified generically as hydroxy-aryl, polymer with substituted benzene, cyanate (PMN P-10-83) is...

XUV-induced reactions in benzene on sub-10 fs timescale: nonadiabatic relaxation and proton migration.

PubMed

Galbraith, M C E; Smeenk, C T L; Reitsma, G; Marciniak, A; Despré, V; Mikosch, J; Zhavoronkov, N; Vrakking, M J J; Kornilov, O; Lépine, F

2017-08-02

Unraveling ultrafast dynamical processes in highly excited molecular species has an impact on our understanding of chemical processes such as combustion or the chemical composition of molecular clouds in the universe. In this article we use short (<7 fs) XUV pulses to produce excited cationic states of benzene molecules and probe their dynamics using few-cycle VIS/NIR laser pulses. The excited states produced by the XUV pulses lie in an especially complex spectral region where multi-electronic effects play a dominant role. We show that very fast τ ≈ 20 fs nonadiabatic processes dominate the relaxation of these states, in agreement with the timescale expected for most excited cationic states in benzene. In the CH 3 + fragmentation channel of the doubly ionized benzene cation we identify pathways that involve structural rearrangement and proton migration to a specific carbon atom. Further, we observe non-trivial transient behavior in this fragment channel, which can be interpreted either in terms of propagation of the nuclear wavepacket in the initially excited electronic state of the cation or as a two-step electronic relaxation via an intermediate state.

INVESTIGATION OF BENZENE OXIDE IN BONE MARROW AND OTHER TISSUES OF F344 RATS FOLLOWING METABOLISM OF BENZENE IN VITRO AND IN VIVO

EPA Science Inventory

This study examines the initial activation of benzene, exploring key aspects of its metabolism by measurement of benzene oxide (BO) and BO-protein adducts in vitro and in vivo. To assess the potential influence of various factors on the production of BO, microsomes were prepare...

Desorption Kinetics of Benzene and Cyclohexane from a Graphene Surface.

PubMed

Smith, R Scott; Kay, Bruce D

2018-01-18

The desorption kinetics for benzene and cyclohexane from a graphene covered Pt(111) surface were investigated using temperature-programmed desorption (TPD). The benzene desorption spectra show well-resolved monolayer and multilayer desorption peaks. The benzene monolayer and submonolayer TPD spectra for coverages greater than ∼0.1 ML have nearly the same desorption peak temperature and have line shapes which are consistent with first-order desorption kinetics. For benzene coverages greater than 1 ML, the TPD spectra align on a common leading edge which is consistent with zero-order desorption. An "inversion" procedure in which the prefactor is varied to find the value that best reproduces the entire set of experimental desorption spectra was used to analyze the benzene data. The inversion analysis of the benzene TPD spectra yielded a desorption activation energy of 54 ± 3 kJ/mol with a prefactor of 10 17±1 s -1 . The TPD spectra for cyclohexane also have well-resolved monolayer and multilayer desorption features. The desorption leading edges for the monolayer and the multilayer TPD spectra are aligned indicating zero-order desorption kinetics in both cases. An Arrhenius analysis of the monolayer cyclohexane TPD spectra yielded a desorption activation energy of 53.5 ± 2 kJ/mol with a prefactor of 10 16±1 ML s -1 .

40 CFR 80.1230 - What are the gasoline benzene requirements for refiners and importers?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 16 2011-07-01 2011-07-01 false What are the gasoline benzene... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Gasoline Benzene Requirements § 80.1230 What are the gasoline benzene requirements for refiners...

40 CFR 80.1230 - What are the gasoline benzene requirements for refiners and importers?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false What are the gasoline benzene... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Gasoline Benzene Requirements § 80.1230 What are the gasoline benzene requirements for refiners...

40 CFR 80.1230 - What are the gasoline benzene requirements for refiners and importers?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 17 2012-07-01 2012-07-01 false What are the gasoline benzene... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Gasoline Benzene Requirements § 80.1230 What are the gasoline benzene requirements for refiners...

40 CFR 80.1230 - What are the gasoline benzene requirements for refiners and importers?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 17 2014-07-01 2014-07-01 false What are the gasoline benzene... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Gasoline Benzene Requirements § 80.1230 What are the gasoline benzene requirements for refiners...

40 CFR 80.1230 - What are the gasoline benzene requirements for refiners and importers?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 17 2013-07-01 2013-07-01 false What are the gasoline benzene... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Gasoline Benzene Requirements § 80.1230 What are the gasoline benzene requirements for refiners...

Dermal exposure assessment to benzene and toluene using charcoal cloth pads.

PubMed

van Wendel de Joode, Berna; Tielemans, Erik; Vermeulen, Roel; Wegh, Hillion; Kromhout, Hans

2005-01-01

Charcoal cloth pads have been used to assess volatile chemicals on the skin in a laboratory setting; however, they have not yet been applied to measure dermal exposure in occupational settings. This study aimed at evaluating whether charcoal pads can be used to assess dermal exposure to benzene and toluene in workers of a petrochemical plant. Inhalation and dermal exposure levels to benzene and toluene were assessed for workers of a petrochemical plant performing different jobs. Benzene uptake was assessed by determining S-phenylmercapturic acid in workers' urine samples. Dermal exposure levels on the charcoal pads were adjusted for ambient air levels of benzene and toluene by subtracting the amount of benzene or toluene measured in personal air from the amount of benzene or toluene measured on the charcoal pad. In general, measured external and internal exposure levels were low. The estimated contribution of the dermal route to internal benzene exposure levels was less than 0.06% for all jobs. Toluene personal air concentrations and benzene and toluene dermal exposure levels differed statistically significantly between job titles. For benzene, differences between jobs were larger for adjusted dermal exposures (maximum 17-fold, P = 0.02) than for inhalation exposures (maximum two-fold, P = 0.08). Also for toluene, although less clear, differences between jobs were larger for adjusted dermal exposures (maximum 23-fold, P = 0.01) as compared to inhalation exposures (maximum 10-fold, P = 0.01). Charcoal pads appeared to measure dermal exposures to benzene and toluene in addition to ambient air levels. Future studies applying charcoal cloth pads for the dermal exposure assessment at workplaces with higher dermal exposure to organic solvents may provide more insight into the biological relevance of dermal exposure levels measured by charcoal cloth pads. In addition, the design of the dermal sampler might be improved by configuring a dermal sampler, where part of the

40 CFR 80.1361 - What penalties apply under the gasoline benzene program?

Code of Federal Regulations, 2011 CFR

2011-07-01

... gasoline benzene program? 80.1361 Section 80.1361 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1361 What penalties apply under the gasoline benzene program? (a) Any person liable for a...

40 CFR 80.1361 - What penalties apply under the gasoline benzene program?

Code of Federal Regulations, 2012 CFR

2012-07-01

... gasoline benzene program? 80.1361 Section 80.1361 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1361 What penalties apply under the gasoline benzene program? (a) Any person liable for a...

40 CFR 80.1361 - What penalties apply under the gasoline benzene program?

Code of Federal Regulations, 2010 CFR

2010-07-01

... gasoline benzene program? 80.1361 Section 80.1361 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1361 What penalties apply under the gasoline benzene program? (a) Any person liable for a...

40 CFR 80.1361 - What penalties apply under the gasoline benzene program?

Code of Federal Regulations, 2014 CFR

2014-07-01

... gasoline benzene program? 80.1361 Section 80.1361 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1361 What penalties apply under the gasoline benzene program? (a) Any person liable for a...

40 CFR 80.1361 - What penalties apply under the gasoline benzene program?

Code of Federal Regulations, 2013 CFR

2013-07-01

... gasoline benzene program? 80.1361 Section 80.1361 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1361 What penalties apply under the gasoline benzene program? (a) Any person liable for a...

Diffusion of benzene confined in the oriented nanochannels of chrysotile asbestos fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mamontov, E.; Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742-2115; Kumzerov, Yu.A.

We used quasielastic neutron scattering to study the dynamics of benzene that completely fills the nanochannels of chrysotile asbestos fibers with a characteristic diameter of about 5 nm. The macroscopical alignment of the nanochannels in fibers provided an interesting opportunity to study anisotropy of the dynamics of confined benzene by means of collecting the data with the scattering vector either parallel or perpendicular to the fibers axes. The translational diffusive motion of benzene molecules was found to be isotropic. While bulk benzene freezes at 278.5 K, we observed the translational dynamics of the supercooled confined benzene on the time scalemore » of hundreds of picoseconds even below 200 K, until at about 160 K its dynamics becomes too slow for the {mu}eV resolution of the neutron backscattering spectrometer. The residence time between jumps for the benzene molecules measured in the temperature range of 260 K to 320 K demonstrated low activation energy of 2.8 kJ/mol.« less

Structural Degradation and Swelling of Lipid Bilayer under the Action of Benzene.

PubMed

Odinokov, Alexey; Ostroumov, Denis

2015-12-03

Benzene and other nonpolar organic solvents can accumulate in the lipid bilayer of cellular membranes. Their effect on the membrane structure and fluidity determines their toxic properties and antibiotic action of the organic solvents on the bacteria. We performed molecular dynamics simulations of the interaction of benzene with the dimyristoylphosphatidylcholine (DMPC) bilayer. An increase in the membrane surface area and fluidity was clearly detected. Changes in the acyl chain ordering, tilt angle, and overall bilayer thickness were, however, much less marked. The dependence of all computed quantities on the benzene content showed two regimes separated by the solubility limit of benzene in water. When the amount of benzene exceeded this point, a layer of almost pure benzene started to grow between the membrane leaflets. This process corresponds to the nucleation of a new phase and provides a molecular mechanism for the mechanical rupture of the bilayer under the action of nonpolar compounds.

Alternatives for Benzene in the Extraction of Bitumen Fume from Exposure Sample Media.

PubMed

Sutter, Benjamin; Ravera, Christel; Hussard, Caroline; Langlois, Eddy

2016-01-01

Benzene is frequently used to extract collected bitumen fumes from personal sampler substrates. However, this solvent is particularly dangerous because of its carcinogenicity (group 1 of the International Agency for Research on Cancer classification). Therefore, to prevent the exposure of laboratory technicians to benzene during the fume extraction step from samplers, a compromise had to be found to identify a less toxic solvent with the same extraction capacity. To compare the extraction capacities of selected solvents, bitumen fumes were generated in the laboratory from three different batches of road surfacing bitumen collected on dedicated bitumen fume samplers. The samplers were then extracted by benzene and the solvents tested. Of 11 selected solvents less toxic than benzene and used in studies on bitumen and bitumen fume analyses, n-hexane and n-heptane were identified as alternatives to benzene. In particular, the results demonstrated that n-heptane was the best candidate solvent for benzene replacement, due to its extraction efficiency comparable to benzene for the three bitumen fumes tested and its low toxicity, which is highly compatible with benzene replacement. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Which ornamental plant species effectively remove benzene from indoor air?

NASA Astrophysics Data System (ADS)

Liu, Yan-Ju; Mu, Yu-Jing; Zhu, Yong-Guan; Ding, Hui; Crystal Arens, Nan

Phytoremediation—using plants to remove toxins—is an attractive and cost effective way to improve indoor air quality. This study screened ornamental plants for their ability to remove volatile organic compounds from air by fumigating 73 plant species with 150 ppb benzene, an important indoor air pollutant that poses a risk to human health. The 10 species found to be most effective at removing benzene from air were fumigated for two more days (8 h per day) to quantify their benzene removal capacity. Crassula portulacea, Hydrangea macrophylla, Cymbidium Golden Elf., Ficus microcarpa var. fuyuensis, Dendranthema morifolium, Citrus medica var. sarcodactylis, Dieffenbachia amoena cv. Tropic Snow; Spathiphyllum Supreme; Nephrolepis exaltata cv. Bostoniensis; Dracaena deremensis cv. Variegata emerged as the species with the greatest capacity to remove benzene from indoor air.

Self-collected breath sampling for monitoring low-level benzene exposures among automobile mechanics.

PubMed

Egeghy, Peter P; Nylander-French, Leena; Gwin, Kristin K; Hertz-Picciotto, Irva; Rappaport, Stephen M

2002-07-01

Automobile mechanics are exposed to benzene through their contact with gasoline vapor and engine exhaust. This study investigated the benzene uptake associated with these exposures. We first evaluated the reliability of self-collected breath samples among a subset of subjects and found good agreement between these samples and those collected under expert supervision (intraclass correlation coefficient 0.79, n = 69). We then used self-monitoring together with a longitudinal sampling design (with up to three measurements per worker) to measure benzene in air and benzene in end-exhaled breath among 81 workers from 12 automobile repair garages in North Carolina. A statistically significant difference (P < 0.0001, Mann-Whitney rank sum test) was observed between non-smokers and smokers for post-exposure benzene concentration in breath (median values of 18.9 and 39.1 micro g/m(3), respectively). Comparing pre- and post-exposure breath concentrations within these two groups, the difference was significant among non-smokers (P < 0.0001) but not significant among smokers (P > 0.05). Mixed effects regression analysis using backwards elimination yielded five significant predictors of benzene concentration in breath, namely benzene exposure (P < 0.0001), pre-exposure benzene concentration in breath (P = 0.021), smoking status (P < 0.0001), fuel system work (P = 0.0043) and carburetor cleaner use (P < 0.0001). The between-person variance component comprised only 28% of the total variance in benzene levels in breath, indicating that differences among individuals related to physiological and metabolic characteristics had little influence on benzene uptake among these workers.

Association between Promoter Methylation of Gene ERCC3 and Benzene Hematotoxicity

PubMed Central

Lin, Feiliang; Hou, Fenxia; Li, Guilan; Zhu, Caiying; Xu, Peiyu; Xing, Caihong; Wang, Qianfei

2017-01-01

Benzene is a primary industrial chemical and a ubiquitous environmental pollutant. ERCC3 is a key player in nucleotide excision repair. Recent studies suggested that site-specific methylation is a possible mechanism of the transcriptional dysregulation by blocking transcription factors binding. We previously found that the average promoter methylation level of ERCC3 was increased in benzene-exposed workers. In order to test whether specific CpG sites of ERCC3 play an important role in benzene-induced epigenetic changes and whether the specific methylation patterns are associated with benzene hematotoxicity, we analyzed the promoter methylation levels of individual CpG sites, transcription factor binding motif and the correlation between aberrant CpG methylation and hematotoxicity in 76 benzene-exposed workers and 24 unexposed controls in China. Out of all the CpGs analyzed, two CpG units located 43 bp upstream and 99 bp downstream of the transcription start site of ERCC3 (CpG 2–4 and CpG 17–18, respectively), showed the most pronounced increase in methylation levels in benzene-exposed workers, compared with unexposed controls (Mean ± SD: 5.86 ± 2.77% vs. 4.92 ± 1.53%, p = 0.032; 8.45 ± 4.09% vs. 6.79 ± 2.50%, p = 0.024, respectively). Using the JASPAR CORE Database, we found that CpG 2–4 and CpG 17–18 were bound by three putative transcription factors (TFAP2A, E2F4 and MZF1). Furthermore, the methylation levels for CpG 2–4 were correlated negatively with the percentage of neutrophils (β = −0.676, p = 0.005) in benzene-exposed workers. This study demonstrates that CpG-specific DNA methylation in the ERCC3 promoter region may be involved in benzene-induced epigenetic modification and it may contribute to benzene-induced hematotoxicity. PMID:28813025

Environmental exposure to benzene: an update.

PubMed Central

Wallace, L

1996-01-01

During the 1990s, several large-scale studies of benzene concentrations in air, food, and blood have added to our knowledge of its environmental occurrence. In general, the new studies have confirmed the earlier findings of the U.S. Environmental Protection Agency Total Exposure Assessment Methodology (TEAM) studies and other large-scale studies in Germany and the Netherlands concerning the levels of exposure and major sources. For example, the new studies found that personal exposures exceeded indoor concentrations of benzene, which in turn exceeded outdoor concentrations. The new studies of food concentrations have confirmed earlier indications that food is not an important pathway for benzene exposure. The results of the National Health and Nutrition Examination Survey on blood levels in a nationwide sample of 883 persons are in good agreement with the concentrations in exhaled breath measured in about 800 persons a decade earlier in the TEAM studies. Major sources of exposure continue to be active and passive smoking, auto exhaust, and driving or riding in automobiles. New methods in breath and blood sampling and analysis offer opportunities to investigate short-term peak exposures and resulting body burden under almost any conceivable field conditions. PMID:9118882

46 CFR 197.565 - Notifying personnel of benzene hazards.

Code of Federal Regulations, 2010 CFR

2010-10-01

... personal protective equipment in emergency situations; (vi) The meaning of a regulated area and the means..., control measures such as personal protection equipment, and first aid procedures for benzene. A copy of... to benzene; (iv) The measures that may be taken and the equipment that may be used to protect persons...

46 CFR 197.565 - Notifying personnel of benzene hazards.

Code of Federal Regulations, 2011 CFR

2011-10-01

... personal protective equipment in emergency situations; (vi) The meaning of a regulated area and the means..., control measures such as personal protection equipment, and first aid procedures for benzene. A copy of... to benzene; (iv) The measures that may be taken and the equipment that may be used to protect persons...

Toxicity of Naphthalene and Benzene on Tribollium castaneum Herbst.

PubMed

Pajaro-Castro, Nerlis; Caballero-Gallardo, Karina; Olivero-Verbel, Jesus

2017-06-21

Naphthalene and benzene are widely-used volatile organic compounds. The aim of this research was to examine the toxicological effects of naphthalene and benzene against Tribolium castaneum as an animal model. Adult insects were exposed to these aromatic compounds to assess mortality after 4-48 h of exposure. The lethal concentration 50 (LC 50 ) for naphthalene, naphthalin, and benzene were 63.6 µL/L, 20.0 µL/L, and 115.9 µL/L in air, respectively. Real-time polymerase chain reaction (PCR) analysis revealed expression changes in genes related to oxidative stress and metabolism [Glutathione S-Transferase (Gst), and Cytochrome P450 6BQ8 (Cyp6bq8)]; reproduction and metamorphosis [Hormone receptor in 39-like protein (Hr39), Ecdysone receptor: (Ecr), and Chitin synthase 2 (Chs2)]; and neurotransmission [Histamine-gated chloride channel 2 (Hiscl2)] in insects exposed for 4 h to 70.2 µL/L naphthalene. Adults exposed to benzene (80 µL/L; 4 h) overexpressed genes related to neurotransmission [GABA-gated anion channel (Rdl), Hiscl2, and GABA-gated ion channel (Grd)]; reproduction and metamorphosis [Ultraspiracle nuclear receptor (USP), Ecr; and Hr39]; and development (Chs2). The data presented here provides evidence that naphthalene and benzene inhalation are able to induce alterations on reproduction, development, metamorphosis, oxidative stress, metabolism, neurotransmission, and death of the insect.

Photocatalytic Hydrogen-Evolution Cross-Couplings: Benzene C-H Amination and Hydroxylation.

PubMed

Zheng, Yi-Wen; Chen, Bin; Ye, Pan; Feng, Ke; Wang, Wenguang; Meng, Qing-Yuan; Wu, Li-Zhu; Tung, Chen-Ho

2016-08-17

We present a blueprint for aromatic C-H functionalization via a combination of photocatalysis and cobalt catalysis and describe the utility of this strategy for benzene amination and hydroxylation. Without any sacrificial oxidant, we could use the dual catalyst system to produce aniline directly from benzene and ammonia, and phenol from benzene and water, both with evolution of hydrogen gas under unusually mild conditions in excellent yields and selectivities.

Disturbance response indicators of Impatiens walleriana exposed to benzene and chromium.

PubMed

Campos, V; Lessa, S S; Ramos, R L; Shinzato, M C; Medeiros, T A M

2017-08-03

The purpose of this study was to evaluate the remediation potential and disturbance response indicators of Impatiens walleriana exposed to benzene and chromium. Numerous studies over the years have found abundant evidence of the carcinogenicity of benzene and chromium (VI) in humans. Benzene and chromium are two toxic industrial chemicals commonly found together at contaminated sites, and one of the most common management strategies employed in the recovery of sites contaminated by petroleum products and trace metals is in situ remediation. Given that increasing interest has focused on the use of plants as depollution agents, direct injection tests and benzene misting were performed on I. walleriana to evaluate the remediation potential of this species. I. walleriana accumulated hexavalent chromium, mainly in the root system (164.23 mg kg -1 ), to the detriment of the aerial part (39.72 mg kg -1 ), and presented visible damage only at the highest concentration (30 mg L -1 ). Unlike chromium (VI), chromium (III) was retained almost entirely by the soil, leaving it available for removal by phytotechnology. However, after the contamination stopped, I. walleriana responded positively to the detoxification process, recovering its stem stiffness and leaf color. I. walleriana showed visible changes such as leaf chlorosis during the ten days of benzene contamination. When benzene is absorbed by the roots, it is translocated to and accumulated in the plant's aerial part. This mechanism the plant uses ensures its tolerance to the organic compound, enabling the species to survive and reproduce after treatment with benzene. Although I. walleriana accumulates minor amounts of hexavalent chromium in the aerial part, this amount suffices to induce greater oxidative stress and to increase the amount of hydrogen peroxide when compared to that of benzene. It was therefore concluded that I. walleriana is a species that possesses desirable characteristics for phytotechnology.

Electrophilic and free radical nitration of benzene and toluene with various nitrating agents*

PubMed Central

Olah, George A.; Lin, Henry C.; Olah, Judith A.; Narang, Subhash C.

1978-01-01

Electrophilic nitration of toluene and benzene was studied under various conditions with several nitrating systems. It was found that high orthopara regioselectivity is prevalent in all reactions and is independent of the reactivity of the nitrating agent. The methyl group of toluene is predominantly ortho-para directing under all reaction conditions. Steric factors are considered to be important but not the sole reason for the variation in the ortho/para ratio. The results reinforce our earlier views that, in electrophilic aromatic nitrations with reactive nitrating agents, substrate and positional selectivities are determined in two separate steps. The first step involves a π-aromatic-NO2+ ion complex or encounter pair, whereas the subsequent step is of arenium ion nature (separate for the ortho, meta, and para positions). The former determines substrate selectivity, whereas the latter determines regioselectivity. Thermal free radical nitration of benzene and toluene with tetranitromethane in sharp contrast gave nearly statistical product distributions. PMID:16592503

40 CFR 721.10260 - Benzene, 1,3-bis(1-chloro-1-methylethyl)-.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzene, 1,3-bis(1-chloro-1... Specific Chemical Substances § 721.10260 Benzene, 1,3-bis(1-chloro-1-methylethyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1,3...

40 CFR 721.10280 - Benzene ethenyl-, polymer with 1,3-butadiene, brominated.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzene ethenyl-, polymer with 1,3... Specific Chemical Substances § 721.10280 Benzene ethenyl-, polymer with 1,3-butadiene, brominated. (a... benzene ethenyl-, polymer with 1,3-butadiene, brominated (PMN P-10-476; CAS No. 1195978-93-8)) is subject...

40 CFR 721.10260 - Benzene, 1,3-bis(1-chloro-1-methylethyl)-.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzene, 1,3-bis(1-chloro-1... Specific Chemical Substances § 721.10260 Benzene, 1,3-bis(1-chloro-1-methylethyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1,3...

40 CFR 721.10260 - Benzene, 1,3-bis(1-chloro-1-methylethyl)-.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzene, 1,3-bis(1-chloro-1... Specific Chemical Substances § 721.10260 Benzene, 1,3-bis(1-chloro-1-methylethyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1,3...

40 CFR 721.10280 - Benzene ethenyl-, polymer with 1,3-butadiene, brominated.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzene ethenyl-, polymer with 1,3... Specific Chemical Substances § 721.10280 Benzene ethenyl-, polymer with 1,3-butadiene, brominated. (a... benzene ethenyl-, polymer with 1,3-butadiene, brominated (PMN P-10-476; CAS No. 1195978-93-8)) is subject...

Diallyl trisulfide (DATS) suppresses benzene-induced cytopenia by modulating haematopoietic cell apoptosis.

PubMed

Han, Wenting; Wang, Shuo; Jiang, Lulu; Wang, Hui; Li, Ming; Wang, Xujing; Xie, Keqin

2017-12-01

Benzene is a well-known occupational and environmental toxicant associated with cytopenia, which is characterized by a disorder in the peripheral blood cell counts. However, no effective preventive strategy has been developed yet to tackle the exposure to benzene in daily life. The aim of this study was to evaluate the protective effects of diallyl trisulfide (DATS) on benzene-induced haematopoietic damage and to reveal its potential mechanisms of action. In our study, male Sprague-Dawley rats were divided into six groups. Rats were administered with benzene (1.3 g/kg BW by gavage) to establish the benzene poisoning model, while the DATS treatment groups were treated with benzene plus DATS (15 mg/kg, 30 mg/kg, 45 mg/kg, respectively, by gavage) for 28 days. Our results demonstrated that the counts of peripheral blood WBC and RBC decreased to 31.0% and 79.2%, respectively, in the benzene poisoning model group compared to the control. However, blood cell counts were restored by DATS treatment (30 mg/kg, 45 mg/kg). The apoptosis rates of peripheral blood mononuclear cells (PBMCs) and bone marrow cells (BMCs) were increased to 274% and 284%, respectively, following benzene exposure. Furthermore, expression levels of Bcl-2, PI3K and p-Akt were downregulated and those of Bax were upregulated in both cell types. Moreover, the oxidative parameters (oxygen species, malonaldehyde) were significantly increased, while the non-enzymatic GSH/GSSG ratios and the activities of enzymatic antioxidants (superoxide dismutase, glutathione peroxidase and catalase) were decreased. Interestingly, DATS treatment can restore the WBC number by 267.1% and 304.8% while RBC number by 108.6% and 117.7% in 30,45 mg/k DATS treated groups. In summary, we demonstrated that benzene-induced cytopenia was related to the apoptosis of PBMCs and BMCs, and DATS treatment could prevent benzene-induced cytopenia by suppressing oxidative stress-mediated cell apoptosis via the PI3K/Akt pathway. Copyright

1-(3,3-Dichloro-all-yloxy)-2-nitro-benzene.

PubMed

Ren, Dong-Mei; Wang, Yong-Yi

2012-04-01

In the title compound, C(9)H(7)Cl(2)NO(3), the dihedral angle between the benzene ring and the plane of the nitro group is 50.2 (1)°, and that between the benzene ring and the best plane through the dichloro-allyl fragment is 40.1 (1)°.

Infrared Spectroscopy of Metal Ion Complexes: Models for Metal Ligand Interactions and Solvation

NASA Astrophysics Data System (ADS)

Duncan, Michael

2006-03-01

Weakly bound complexes of the form M^+-Lx (M=Fe, Ni, Co, etc.; L=CO2, C2H2, H2O, benzene, N2) are prepared in supersonic molecular beams by laser vaporization in a pulsed-nozzle cluster source. These species are mass analyzed and size-selected in a reflectron time-of-flight mass spectrometer. Clusters are photodissociated at infrared wavelengths with a Nd:YAG pumped infrared optical parametric oscillator/amplifier (OPO/OPA) laser or with a tunable infrared free-electron laser. M^+-(CO2)x complexes absorb near the free CO2 asymmetric stretch near 2349 cm-1 but with an interesting size dependent variation in the resonances. Small clusters have blue-shifted resonances, while larger complexes have additional bands due to surface CO2 molecules not attached to the metal. M^+(C2H2)n complexes absorb near the C-H stretches in acetylene, but resonances in metal complexes are red-shifted with repect to the isolated molecule. Ni^+ and Co^+ complexes with acetylene undergo intracluster cyclization reactions to form cyclobutadiene. Transition metal water complexes are studied in the O-H stretch region, and partial rotational structure can be measured. M^+(benzene) and M^+(benzene)2 ions (M=V, Ti, Al) represent half-sandwich and sandwich species, whose spectra are measured near the free benzene modes. These new IR spectra and their assignments will be discussed as well as other new IR spectra for similar complexes.

Geogenic sources of benzene in aquifers used for public supply, California

USGS Publications Warehouse

Landon, Matthew K.; Belitz, Kenneth

2012-01-01

Statistical evaluation of two large statewide data sets from the California State Water Board's Groundwater Ambient Monitoring and Assessment Program (1973 wells) and the California Department of Public Health (12417 wells) reveals that benzene occurs infrequently (1.7%) and at generally low concentrations (median detected concentration of 0.024 μg/L) in groundwater used for public supply in California. When detected, benzene is more often related to geogenic (45% of detections) than anthropogenic sources (27% of detections). Similar relations are evident for the sum of 17 hydrocarbons analyzed. Benzene occurs most frequently and at the highest concentrations in old, brackish, and reducing groundwater; the detection frequency was 13.0% in groundwater with tritium <1 pCi/L, specific conductance >1600 μS/cm, and anoxic conditions. This groundwater is typically deep (>180 m). Benzene occurs somewhat less frequently in recent, shallow, and reducing groundwater; the detection frequency was 2.6% in groundwater with tritium ≥1 pCi/L, depth <30 m, and anoxic conditions. Evidence for geogenic sources of benzene include: higher concentrations and detection frequencies with increasing well depth, groundwater age, and proximity to oil and gas fields; and higher salinity and lower chloride/iodide ratios in old groundwater with detections of benzene, consistent with interactions with oil-field brines.

Current understandings and perspectives on non-cancer health effects of benzene: A global concern

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bahadar, Haji; Pharmaceutical Sciences Research Center and Faculty of Pharmacy, Tehran University of Medical Sciences; Mostafalou, Sara

Objective: Benzene, as a volatile organic compound, is known as one of the main air pollutants in the environment. The aim of this review is to summarize all available evidences on non-cancerous health effects of benzene providing an overview of possible association of exposure to benzene with human chronic diseases, specially, in those regions of the world where benzene concentration is being poorly monitored. Methodology: A bibliographic search of scientific databases including PubMed, Google Scholar, and Scirus was conducted with key words of “benzene toxic health effects”, “environmental volatile organic compounds”, “diabetes mellitus and environmental pollutants”, “breast cancer and environmentalmore » pollution”, “prevalence of lung cancer”, and “diabetes prevalence”. More than 300 peer reviewed papers were examined. Experimental and epidemiologic studies reporting health effects of benzene and volatile organic compounds were included in the study. Results: Epidemiologic and experimental studies suggest that benzene exposure can lead to numerous non-cancerous health effects associated with functional aberration of vital systems in the body like reproductive, immune, nervous, endocrine, cardiovascular, and respiratory. Conclusion: Chronic diseases have become a health burden of global dimension with special emphasis in regions with poor monitoring over contents of benzene in petrochemicals. Benzene is a well known carcinogen of blood and its components, but the concern of benzene exposure is more than carcinogenicity of blood components and should be evaluated in both epidemiologic and experimental studies. Aspect of interactions and mechanism of toxicity in relation to human general health problems especially endocrine disturbances with particular reference to diabetes, breast and lung cancers should be followed up. - Highlights: • Benzene is a volatile organic compound and established blood carcinogen. • Exposure to benzene

Maternal Personal Exposure to Airborne Benzene and Intrauterine Growth

PubMed Central

Slama, Rémy; Thiebaugeorges, Olivier; Goua, Valérie; Aussel, Lucette; Sacco, Paolo; Bohet, Aline; Forhan, Anne; Ducot, Béatrice; Annesi-Maesano, Isabella; Heinrich, Joachim; Magnin, Guillaume; Schweitzer, Michel; Kaminski, Monique; Charles, Marie-Aline

2009-01-01

Background Studies relying on outdoor pollutants measures have reported associations between air pollutants and birth weight. Objective Our aim was to assess the relation between maternal personal exposure to airborne benzene during pregnancy and fetal growth. Methods We recruited pregnant women in two French maternity hospitals in 2005–2006 as part of the EDEN mother–child cohort. A subsample of 271 nonsmoking women carried a diffusive air sampler for a week during the 27th gestational week, allowing assessment of benzene exposure. We estimated head circumference of the offspring by ultrasound measurements during the second and third trimesters of pregnancy and at birth. Results Median benzene exposure was 1.8 μg/m3 (5th, 95th percentiles, 0.5, 7.5 μg/m3). Log-transformed benzene exposure was associated with a gestational age–adjusted decrease of 68 g in mean birth weight [95% confidence interval (CI), −135 to −1 g] and of 1.9 mm in mean head circumference at birth (95% CI, −3.8 to 0.0 mm). It was associated with an adjusted decrease of 1.9 mm in head circumference assessed during the third trimester (95% CI, −4.0 to 0.3 mm) and of 1.5 mm in head circumference assessed at the end of the second trimester of pregnancy (95% CI, −3.1 to 0 mm). Conclusions Our prospective study among pregnant women is one of the first to rely on personal monitoring of exposure; a limitation is that exposure was assessed during 1 week only. Maternal benzene exposure was associated with decreases in birth weight and head circumference during pregnancy and at birth. This association could be attributable to benzene and a mixture of associated traffic-related air pollutants. PMID:19672414

Maternal personal exposure to airborne benzene and intrauterine growth.

PubMed

Slama, Rémy; Thiebaugeorges, Olivier; Goua, Valérie; Aussel, Lucette; Sacco, Paolo; Bohet, Aline; Forhan, Anne; Ducot, Béatrice; Annesi-Maesano, Isabella; Heinrich, Joachim; Magnin, Guillaume; Schweitzer, Michel; Kaminski, Monique; Charles, Marie-Aline

2009-08-01

Studies relying on outdoor pollutants measures have reported associations between air pollutants and birth weight. Our aim was to assess the relation between maternal personal exposure to airborne benzene during pregnancy and fetal growth. We recruited pregnant women in two French maternity hospitals in 2005-2006 as part of the EDEN mother-child cohort. A subsample of 271 nonsmoking women carried a diffusive air sampler for a week during the 27th gestational week, allowing assessment of benzene exposure. We estimated head circumference of the offspring by ultrasound measurements during the second and third trimesters of pregnancy and at birth. Median benzene exposure was 1.8 microg/m(3) (5th, 95th percentiles, 0.5, 7.5 microg/m(3)). Log-transformed benzene exposure was associated with a gestational age-adjusted decrease of 68 g in mean birth weight [95% confidence interval (CI), -135 to -1 g] and of 1.9 mm in mean head circumference at birth (95% CI, -3.8 to 0.0 mm). It was associated with an adjusted decrease of 1.9 mm in head circumference assessed during the third trimester (95% CI, -4.0 to 0.3 mm) and of 1.5 mm in head circumference assessed at the end of the second trimester of pregnancy (95% CI, -3.1 to 0 mm). Our prospective study among pregnant women is one of the first to rely on personal monitoring of exposure; a limitation is that exposure was assessed during 1 week only. Maternal benzene exposure was associated with decreases in birth weight and head circumference during pregnancy and at birth. This association could be attributable to benzene and a mixture of associated traffic-related air pollutants.

The pyrolysis of toluene and ethyl benzene

NASA Technical Reports Server (NTRS)

Sokolovskaya, V. G.; Samgin, V. F.; Kalinenko, R. A.; Nametkin, N. S.

1987-01-01

The pyrolysis of toluene at 850 to 950 C gave mainly H2, CH4, and benzene; PhEt at 650 to 750 C gave mainly H2, CH4, styrene, benzene, and toluene. The rate constants for PhEt pyrolysis were 1000 times higher than those for toluene pyrolysis; the chain initiation rate constants differed by the same factor. The activation energy differences were 46 kJ/mole for the total reaction and 54 kJ/mole for chain initiation. The chain length was evaluated for the PhEt case (10 + or - 2).

40 CFR 721.1325 - Benzene, 1-(1-methyl-bu-toxy)-4-nitro-.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzene, 1-(1-methyl-bu-toxy)-4-nitro... Substances § 721.1325 Benzene, 1-(1-methyl-bu-toxy)-4-nitro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1-(1-methylbutoxy)-4-nitro- (PMN P...

40 CFR 721.1325 - Benzene, 1-(1-methyl-bu-toxy)-4-nitro-.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzene, 1-(1-methyl-bu-toxy)-4-nitro... Substances § 721.1325 Benzene, 1-(1-methyl-bu-toxy)-4-nitro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1-(1-methylbutoxy)-4-nitro- (PMN P...

40 CFR 721.1325 - Benzene, 1-(1-methyl-bu-toxy)-4-nitro-.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, 1-(1-methyl-bu-toxy)-4-nitro... Substances § 721.1325 Benzene, 1-(1-methyl-bu-toxy)-4-nitro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1-(1-methylbutoxy)-4-nitro- (PMN P...

40 CFR 721.1325 - Benzene, 1-(1-methyl-bu-toxy)-4-nitro-.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzene, 1-(1-methyl-bu-toxy)-4-nitro... Substances § 721.1325 Benzene, 1-(1-methyl-bu-toxy)-4-nitro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1-(1-methylbutoxy)-4-nitro- (PMN P...

40 CFR 721.1325 - Benzene, 1-(1-methyl-bu-toxy)-4-nitro-.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzene, 1-(1-methyl-bu-toxy)-4-nitro... Substances § 721.1325 Benzene, 1-(1-methyl-bu-toxy)-4-nitro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1-(1-methylbutoxy)-4-nitro- (PMN P...

Molecular simulation study on Hofmeister cations and the aqueous solubility of benzene.

PubMed

Ganguly, Pritam; Hajari, Timir; van der Vegt, Nico F A

2014-05-22

We study the ion-specific salting-out process of benzene in aqueous alkali chloride solutions using Kirkwood-Buff (KB) theory of solutions and molecular dynamics simulations with different empirical force field models for the ions and benzene. Despite inaccuracies in the force fields, the simulations indicate that the decrease of the Setchenow salting-out coefficient for the series NaCl > KCl > RbCl > CsCl is determined by direct benzene-cation correlations, with the larger cations showing weak interactions with benzene. Although ion-specific aqueous solubilities of benzene may be affected by indirect ion-ion, ion-water, and water-water correlations, too, these correlations are found to be unimportant, with little to no effect on the Setchenow salting-out coefficients of the various salts. We further considered LiCl, which is experimentally known to be a weaker salting-out agent than NaCl and KCl and, therefore, ranks at an unusual position within the Hofmeister cation series. The simulations indicate that hydrated Li(+) ions can take part of the benzene hydration shell while the other cations are repelled by it. This causes weaker Li(+) exclusion around the solute and a resulting, weaker salting-out propensity of LiCl compared to that of the other salts. Removing benzene-water and benzene-salt electrostatic interactions in the simulations does not affect this mechanism, which may therefore also explain the smaller effect of LiCl, as compared to that of NaCl or KCl, on aqueous solvation and hydrophobic interaction of nonpolar molecules.

Nucleotide sequencing and characterization of the genes encoding benzene oxidation enzymes of Pseudomonas putida.

PubMed Central

Irie, S; Doi, S; Yorifuji, T; Takagi, M; Yano, K

1987-01-01

The nucleotide sequence of the genes from Pseudomonas putida encoding oxidation of benzene to catechol was determined. Five open reading frames were found in the sequence. Four corresponding protein molecules were detected by a DNA-directed in vitro translation system. Escherichia coli cells containing the fragment with the four open reading frames transformed benzene to cis-benzene glycol, which is an intermediate of the oxidation of benzene to catechol. The relation between the product of each cistron and the components of the benzene oxidation enzyme system is discussed. Images PMID:3667527

Hydrogeologic characterization and assessment of bioremediation of chlorinated benzenes and benzene in wetland areas, Standard Chlorine of Delaware, Inc. Superfund Site, New Castle County, Delaware, 2009-12

USGS Publications Warehouse

Lorah, Michelle M.; Walker, Charles W.; Baker, Anna C.; Teunis, Jessica A.; Emily Majcher,; Brayton, Michael J.; Raffensperger, Jeff P.; Cozzarelli, Isabelle M.

2015-01-01

Wetlands at the Standard Chlorine of Delaware, Inc. Superfund Site (SCD) in New Castle County, Delaware, are affected by contamination with chlorobenzenes and benzene from past waste storage and disposal, spills, leaks, and contaminated groundwater discharge. In cooperation with the U.S. Environmental Protection Agency, the U.S. Geological Survey began an investigation in June 2009 to characterize the hydrogeology and geochemistry in the wetlands and assess the feasibility of monitored natural attenuation and enhanced bioremediation as remedial strategies. Groundwater flow in the wetland study area is predominantly vertically upward in the wetland sediments and the underlying aquifer, and groundwater discharge accounts for a minimum of 47 percent of the total discharge for the subwatershed of tidal Red Lion Creek. Thus, groundwater transport of contaminants to surface water could be significant. The major contaminants detected in groundwater in the wetland study area included benzene, monochlorobenzene, and tri- and di-chlorobenzenes. Shallow wetland groundwater in the northwest part of the wetland study area was characterized by high concentrations of total chlorinated benzenes and benzene (maximum about 75,000 micrograms per liter [μg/L]), low pH, and high chloride. In the northeast part of the wetland study area, wetland groundwater had low to moderate concentrations of total chlorinated benzenes and benzene (generally not greater than 10,000 μg/L), moderate pH, and high sulfate concentrations. Concentrations in the groundwater in excess of 1 percent of the solubility of the individual chlorinated benzenes indicate that a contaminant source is present in the wetland sediments as dense nonaqueous phase liquids (DNAPLs). Consistently higher contaminant concentrations in the shallow wetland groundwater than deeper in the wetland sediments or the aquifer also indicate a continued source in the wetland sediments, which could include dissolution of DNAPLs and

[Association between polymorphisms of XPD gene and susceptibility to chronic benzene poisoning].

PubMed

Huang, Hui-long; Xu, Jian-ning; Wang, Quan-kai; Wang, Ya-wen; Yang, Min; Chen, Yan; Li, Gui-lan

2006-07-01

To explore the relationship between genetic polymorphisms of XPD gene and susceptibility to chronic benzene poisoning. A case control study was conducted. Eighty patients diagnosed with chronic benzene poisoning and 62 workers occupationally exposed to benzene who were engaged in the same working time and job title as patients were investigated. PCR-RFLP was used for detecting the single nucleotide polymorphisms (SNPs) on codon156, codon312 and codon751 of XPD gene. There was a 2.903 times (95% CI: 1.054 - 7.959, P = 0.039 2) increased risk of chronic benzene poisoning in the subjects carrying XPD 751Gln variant allele compared with those carrying XPD 751Lys/Lys genotype, after adjusted for sex, length of service, smoking and drinking status. The subjects with XPD 751Gln variant allele are more susceptive to benzene.

Benzene observations and source appointment in a region of oil and natural gas development

NASA Astrophysics Data System (ADS)

Halliday, Hannah Selene

Benzene is a primarily anthropogenic volatile organic compound (VOC) with a small number of well characterized sources. Atmospheric benzene affects human health and welfare, and low level exposure (< 0.5 ppbv) has been connected to measureable increases in cancer rates. Benzene measurements have been increasing in the region of oil and natural gas (O&NG) development located to the north of Denver. High time resolution measurements of VOCs were collected using a proton-transfer-reaction quadrupole mass spectrometry (PTR-QMS) instrument at the Platteville Atmospheric Observatory (PAO) in Colorado to investigate how O&NG development impacts air quality within the Wattenburg Gas Field (WGF) in the Denver-Julesburg Basin. The measurements were carried out in July and August 2014 as part of NASA's DISCOVER-AQ field campaign. The PTR-QMS data were supported by pressurized whole air canister samples and airborne vertical and horizontal surveys of VOCs. Unexpectedly high benzene mixing ratios were observed at PAO at ground level (mean benzene = 0.53 ppbv, maximum benzene = 29.3 ppbv), primarily at night (mean nighttime benzene = 0.73 ppbv). These high benzene levels were associated with southwesterly winds. The airborne measurements indicate that benzene originated from within the WGF, and typical source signatures detected in the canister samples implicate emissions from O&NG activities rather than urban vehicular emissions as primary benzene source. This conclusion is backed by a regional toluene-to-benzene ratio analysis which associated southerly flow with vehicular emissions from the Denver area. Weak benzene-to-CO correlations confirmed that traffic emissions were not responsible for the observed high benzene levels. Previous measurements at the Boulder Atmospheric Observatory (BAO) and our data obtained at PAO allow us to locate the source of benzene enhancements between the two atmospheric observatories. Fugitive emissions of benzene from O&NG operations in the

Chromosome-wide aneuploidy study (CWAS) in workers exposed to an established leukemogen, benzene

PubMed Central

Zhang, Luoping; Lan, Qing; Guo, Weihong; Hubbard, Alan E.; Li, Guilan; Rappaport, Stephen M.; McHale, Cliona M.; Shen, Min; Ji, Zhiying; Vermeulen, Roel; Yin, Songnian; Rothman, Nathaniel; Smith, Martyn T.

2011-01-01

Evidence suggests that de novo, therapy-related and benzene-induced acute myeloid leukemias (AML) occur via similar cytogenetic and genetic pathways, several of which involve aneuploidy, the loss or gain of chromosomes. Aneuploidy of specific chromosomes has been detected in benzene-related leukemia patients as well as in healthy benzene-exposed workers, suggesting that aneuploidy precedes and may be a potential mechanism underlying benzene-induced leukemia. Here, we analyzed the peripheral blood lymphocytes of 47 exposed workers and 27 unexposed controls using a novel OctoChrome fluorescence in situ hybridization (FISH) technique that simultaneously detects aneuploidy in all 24 chromosomes. Through this chromosome-wide aneuploidy study (CWAS) approach, we found heterogeneity in the monosomy and trisomy rates of the 22 autosomes when plotted against continuous benzene exposure. In addition, statistically significant, chromosome-specific increases in the rates of monosomy [5, 6, 7, 10, 16 and 19] and trisomy [5, 6, 7, 8, 10, 14, 16, 21 and 22] were found to be dose dependently associated with benzene exposure. Furthermore, significantly higher rates of monosomy and trisomy were observed in a priori defined ‘susceptible’ chromosome sets compared with all other chromosomes. Together, these findings confirm that benzene exposure is associated with specific chromosomal aneuploidies in hematopoietic cells, which suggests that such aneuploidies may play roles in benzene-induced leukemogenesis. PMID:21216845

Benzene contamination at a metal plating facility

NASA Astrophysics Data System (ADS)

Memon, B. A.; Burston, M. R.

2005-08-01

A metal plating facility in central Kentucky was required to complete a RCRA Facility Investigation to address a number of Solid Waste Management Units at the site. Twenty monitoring wells were installed at the facility. Ground water from the wells was sampled for total and dissolved metals, polychlorinated biphenyls, acid extractable compounds, base neutral compounds, and volatile organic compounds. Unexpectedly, relatively large concentrations of benzene, up to 120 μg/l, were detected in samples from some of the wells, including wells that should have been hydraulically upgradient from the facility. As a result of the detection of benzene, the facility completed an investigation to identify the source. A nearby facility had completed a gasoline underground storage tank (UST) closure at about the time of the installation of the 20 wells. Reportedly the UST had small holes when removed. Three potential pathways of migration (a ditch, sanitary sewer, and a sink hole) from the nearby facility to the metal-plating facility and residual soils with very large concentrations of benzene, toluene, ethylbenzene, and xylenes have been identified.

Distribution of chromosome breakpoints in benzene-exposed and unexposed AML patients.

PubMed

Kerzic, Patrick J; Irons, Richard D

2017-10-01

Results of laboratory studies and investigations of occupationally exposed healthy individuals have been used to develop a mode of action for benzene-induced leukemia that mirrors disease following treatment with chemotherapeutic agents. Recently we have described series of AML and MDS cases with benzene exposure history, and have provided cytogenetic, molecular, and pathologic evidence that these cases differ significantly in many features from therapy-related disease. Here we have extended this work, and describe chromosome breakpoints across 441 identifiable regions, in terms of gains or losses, in 710 AML cases collected during the Shanghai Health Study, which include 75 with a history of benzene exposure. Using FISH and cytogenetic analysis, we developed prevalence information and risk ratios for benzene exposure across all regions with a lesion in at least one exposed and unexposed case. These results indicate that AML following benzene exposure mirrors de novo disease, and supports a mechanism for development of hematopoietic disease that bears no resemblance to therapy-related disease. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

A two-dimensional ZnII coordination polymer constructed from benzene-1,2,3-tricarboxylic acid and N,N'-bis[(pyridin-4-yl)methylidene]hydrazine.

PubMed

Wang, Xiangfei; Yang, Fang; Tang, Meng; Yuan, Limin; Liu, Wenlong

2015-07-01

The hydrothermal synthesis of the novel complex poly[aqua(μ4-benzene-1,2,3-tricarboxylato)[μ2-4,4'-(hydrazine-1,2-diylidenedimethanylylidene)dipyridine](μ3-hydroxido)dizinc(II)], [Zn(C9H3O6)(OH)(C12H10N4)(H2O)]n, is described. The benzene-1,2,3-tricarboxylate ligand connects neighbouring Zn4(OH)2 secondary building units (SBUs) producing an infinite one-dimensional chain. Adjacent one-dimensional chains are connected by the N,N'-bis[(pyridin-4-yl)methylidene]hydrazine ligand, forming a two-dimensional layered structure. Adjacent layers are stacked to generate a three-dimensional supramolecular architecture via O-H...O hydrogen-bond interactions. The thermal stability of this complex is described and the complex also appears to have potential for application as a luminescent material.

MGMT hypomethylation is associated with DNA damage in workers exposed to low-dose benzene.

PubMed

Li, Jie; Zhang, Xinjie; He, Zhini; Sun, Qing; Qin, Fei; Huang, Zhenlie; Zhang, Xiao; Sun, Xin; Liu, Linhua; Chen, Liping; Gao, Chen; Wang, Shan; Wang, Fangping; Li, Daochuan; Zeng, Xiaowen; Deng, Qifei; Wang, Qing; Zhang, Bo; Tang, Huanwen; Chen, Wen; Xiao, Yongmei

2017-07-01

This study aims to assess the effects of low-dose benzene on DNA damage and O 6 -methylguanine-DNA methyltransferase (MGMT) methylation in occupational workers. We recruited 96 nonsmoking male petrochemical industry workers exposed to low-dose benzene and 100 matched control workers. Urinary S-phenylmercapturic acid (SPMA) and S-benzylmercapturic acid (SBMA) were measured for indicating internal exposure of benzene and toluene. The degree of DNA damage was determined by the Comet assay. The levels of MGMT methylation were detected quantitatively by bisulphite-PCR pyrosequencing assay. The benzene-exposed workers had significantly higher levels of urinary SPMA, degree of DNA damage but decreased MGMT methylation than the controls (all p < 0.05). In contrast, the level of urinary SBMA does not differ between benzene-exposed workers and the controls. In all participants, MGMT methylation was negatively associated with the urinary SPMA and the degree of DNA damage, indicating that epigenetic regulation might be involved in response to low-dose benzene exposure-induced genetic damage. MGMT methylation could be a potent biomarker associated with low-dose benzene exposure and benzene-induced DNA damage.

Methods for visualising active microbial benzene degraders in in situ microcosms.

PubMed

Schurig, Christian; Mueller, Carsten W; Höschen, Carmen; Prager, Andrea; Kothe, Erika; Beck, Henrike; Miltner, Anja; Kästner, Matthias

2015-01-01

Natural attenuation maybe a cost-efficient option for bioremediation of contaminated sites but requires knowledge about the activity of degrading microbes under in situ conditions. In order to link microbial activity to the spatial distribution of contaminant degraders, we combined the recently improved in situ microcosm approach, so-called 'direct-push bacterial trap' (DP-BACTRAP), with nano-scale secondary ion mass spectrometry (NanoSIMS) analysis on samples from contaminated constructed wetlands. This approach is based on initially sterile microcosms amended with (13)C-labelled benzene as a source of carbon and energy for microorganisms. The microcosms were introduced directly in the constructed wetland, where they were colonised by indigenous microorganisms from the sediment. After incubation in the field, the samples were analysed by NanoSIMS, scanning electron microscopy (SEM) and fluorescence microscopy in order to visualise (13)C-labelled microbial biomass on undisturbed samples from the microcosms. With the approach developed, we successfully visualised benzene-degrading microbes on solid materials with high surface area by means of NanoSIMS. Moreover, we could demonstrate the feasibility of NanoSIMS analysis of unembedded porous media with a highly complex topography, which was frequently reasoned to not lead to sufficient results.

40 CFR 80.1358 - What acts are prohibited under the gasoline benzene program?

Code of Federal Regulations, 2013 CFR

2013-07-01

... gasoline benzene program? 80.1358 Section 80.1358 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1358 What acts are prohibited under the gasoline benzene program? No person shall— (a)(1...

40 CFR 80.1358 - What acts are prohibited under the gasoline benzene program?

Code of Federal Regulations, 2011 CFR

2011-07-01

... gasoline benzene program? 80.1358 Section 80.1358 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1358 What acts are prohibited under the gasoline benzene program? No person shall— (a)(1...

40 CFR 80.1358 - What acts are prohibited under the gasoline benzene program?

Code of Federal Regulations, 2010 CFR

2010-07-01

... gasoline benzene program? 80.1358 Section 80.1358 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1358 What acts are prohibited under the gasoline benzene program? No person shall— (a)(1...

40 CFR 80.1358 - What acts are prohibited under the gasoline benzene program?

Code of Federal Regulations, 2012 CFR

2012-07-01

... gasoline benzene program? 80.1358 Section 80.1358 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1358 What acts are prohibited under the gasoline benzene program? No person shall— (a)(1...

40 CFR 80.1358 - What acts are prohibited under the gasoline benzene program?

Code of Federal Regulations, 2014 CFR

2014-07-01

... gasoline benzene program? 80.1358 Section 80.1358 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1358 What acts are prohibited under the gasoline benzene program? No person shall— (a)(1...

Optical Absorption and Raman Spectroscopy of Multiple Shocked Liquid Benzene to 10 GPa

NASA Astrophysics Data System (ADS)

Root, S.

2005-07-01

Liquid benzene samples were multiply shocked to peak pressures ranging from 3 GPa to 10 GPa to examine physical and chemical changes in benzene. A xenon flashlamp was used to probe the visible spectrum of benzene for loses in transmitted light intensity caused by changes in the electronic structure (absorption) or a possible liquid to solid phase transition (scattering). Raman spectroscopy was used to corroborate transmission measurements by examining changes in the benzene vibrational modes. The C-C symmetric ring breathing mode (992 cm-1), C-H symmetric stretch (3061 cm-1), along with several weaker modes at 607 cm-1, 1178 cm-1, 1586 cm-1, and 1606 cm-1 were monitored during shock loading. An EOS was developed to calculate the temperature of the shock compressed benzene. The present work has demonstrated that liquid benzene remains unchanged during multiple shock loading up to 10 GPa. Work supported by ONR and DOE.

Crystal structures of N-(3-fluoro-benzo-yl)benzene-sulfonamide and N-(3-fluoro-benzo-yl)-4-methyl-benzene-sulfonamide.

PubMed

Suchetan, P A; Naveen, S; Lokanath, N K; Lakshmikantha, H N; Srivishnu, K S; Supriya, G M

2016-04-01

The crystal structures of two N-(aryl-sulfon-yl)aryl-amides, namely N-(3-fluoro-benzo-yl)benzene-sulfonamide, C13H10FNO3S, (I), and N-(3-fluoro-benzo-yl)-4-methyl-benzene-sulfonamide, C14H12FNO3S, (II), are described and compared with related structures. The dihedral angle between the benzene rings is 82.73 (10)° in (I) compared to 72.60 (12)° in (II). In the crystal of (I), the mol-ecules are linked by C-H⋯O and C-H⋯π inter-actions, resulting in a three-dimensional grid-like architecture, while C-H⋯O inter-actions lead to one-dimensional ribbons in (II). The crystals of both (I) and (II) feature strong but non-structure-directing N-H⋯O hydrogen bonds with R 2 (2)(8) ring motifs. The structure of (I) also features π-π stacking inter-actions.

Near infrared study of water-benzene mixtures at high temperatures and pressures.

PubMed

Jin, Yusuke; Ikawa, Shun-Ichi

2004-08-08

Near-infrared absorption of water-benzene mixtures has been measured at temperatures and pressures in the ranges of 473-673 K and 100-400 bar, respectively. Concentrations of water and benzene in the water-rich phase of the mixtures were obtained from the integrated absorption intensities of the OH stretching overtone transition of water and the CH stretching overtone transition of benzene, respectively. Using these concentrations, the densities of the water-rich phase were estimated and compared with the average densities before mixing, which were calculated from literature densities of neat water and neat benzene. It is found that anomalously large volume expansion on the mixing occurs in the region enclosed by an extended line of the three-phase equilibrium curve and the one-phase critical curve of the mixtures, and the gas-liquid equilibrium curve of water. Furthermore, magnitude of the relative volume change increases with decreasing molar fraction of benzene in the present experimental range. It is suggested that dissolving a small amount of benzene in water induces a change in the fluid density from a liquidlike condition to a gaslike condition in the vicinity of the critical region.

Benzene Exposures and Risk Potential for Vehicle Mechanics from Gasoline and Petroleum-Derived Products.

PubMed

Williams, Pamela R D; Mani, Ashutosh

2015-01-01

Benzene exposures among vehicle mechanics in the United States and abroad were characterized using available data from published and unpublished studies. In the United States, the time-weighted-average (TWA) airborne concentration of benzene for vehicle mechanics averaged 0.01-0.05 ppm since at least the late 1970s, with maximal TWA concentrations ranging from 0.03 to 0.38 ppm. Benzene exposures were notably lower in the summer than winter and in the Southwest compared to other geographic regions, but significantly higher during known gasoline-related tasks such as draining a gas tank or changing a fuel pump or fuel filter. Measured airborne concentrations of benzene were also generally greater for vehicle mechanics in other countries, likely due to the higher benzene content of gasoline and other factors. Short-term airborne concentrations of benzene frequently exceeded 1 ppm during gasoline-related tasks, but remained below 0.2 ppm for tasks involving other petroleum-derived products such as carburetor and brake cleaner or parts washer solvent. Application of a two-zone mathematical model using reasonable input values from the literature yielded predicted task-based benzene concentrations during gasoline and aerosol spray cleaner scenarios similar to those measured for vehicle mechanics during these types of tasks. When evaluated using appropriate biomarkers, dermal exposures were found to contribute little to total benzene exposures for this occupational group. Available data suggest that vehicle mechanics have not experienced significant exposures to benzene in the workplace, except perhaps during short-duration gasoline-related tasks, and full-shift benzene exposures have remained well below current and contemporaneous occupational exposure limits. These findings are consistent with epidemiology studies of vehicle mechanics, which have not demonstrated an increased risk of benzene-induced health effects in this cohort of workers. Data and information presented

Colonic migrating motor complexes are inhibited in acute tri-nitro benzene sulphonic acid colitis.

PubMed

Hofma, Ben R; Wardill, Hannah R; Mavrangelos, Chris; Campaniello, Melissa A; Dimasi, David; Bowen, Joanne M; Smid, Scott D; Bonder, Claudine S; Beckett, Elizabeth A; Hughes, Patrick A

2018-01-01

Inflammatory Bowel Disease (IBD) is characterized by overt inflammation of the intestine and is typically accompanied by symptoms of bloody diarrhea, abdominal pain and cramping. The Colonic Migrating Motor Complex (CMMC) directs the movement of colonic luminal contents over long distances. The tri-nitrobenzene sulphonic acid (TNBS) model of colitis causes inflammatory damage to enteric nerves, however it remains to be determined whether these changes translate to functional outcomes in CMMC activity. We aimed to visualize innate immune cell infiltration into the colon using two-photon laser scanning intra-vital microscopy, and to determine whether CMMC activity is altered in the tri-nitro benzene sulphonic (TNBS) model of colitis. Epithelial barrier permeability was compared between TNBS treated and healthy control mice in-vitro and in-vivo. Innate immune activation was determined by ELISA, flow cytometry and by 2-photon intravital microscopy. The effects of TNBS treatment and IL-1β on CMMC function were determined using a specialized organ bath. TNBS colitis increased epithelial barrier permeability in-vitro and in-vivo. Colonic IL-1β concentrations, colonic and systemic CD11b+ cell infiltration, and the number of migrating CD11b+ cells on colonic blood vessels were all increased in TNBS treated mice relative to controls. CMMC frequency and amplitude were inhibited in the distal and mid colon of TNBS treated mice. CMMC activity was not altered by superfusion with IL-1β. TNBS colitis damages the epithelial barrier and increases innate immune cell activation in the colon and systemically. Innate cell migration into the colon is readily identifiable by two-photon intra-vital microscopy. CMMC are inhibited by inflammation, but this is not due to direct effects of IL-1β.

Oxidative desulfurization of benzene fraction on transition metal oxides

NASA Astrophysics Data System (ADS)

Boikov, E. B.; Vishnetskaya, M. V.

2013-02-01

It is established that molecular oxygen is able to oxidize thiophene selectively in a mixture with benzene on V2O5 · MoO3. The introduction of thiophene inhibits the oxidation of benzene. It is shown that the conversion of thiophene during operation of the catalyst is reduced at first and then increases until it reaches its initial value.

Photodissociation spectroscopy of (benzene-toluene) +. Charge delocalization in the hetero-dimer ion

NASA Astrophysics Data System (ADS)

Ohashi, Kazuhiko; Nakane, Youko; Inokuchi, Yoshiya; Nakai, Yasuhiro; Nishi, Nobuyuki

1998-12-01

The electronic spectrum of the benzene-toluene hetero-dimer ion is measured in the 380-1400 nm region. The spectrum shows intense bands around 1175 and 670 nm and a weaker band around 920 nm, which correspond to charge resonance (CR) bands of homo-dimer ions. The observation indicates that the positive charge stays on the benzene part in some probability, although the ionization potential of benzene is 0.4162 eV higher than that of toluene. A local excitation (LE) band is observed around 420 nm, where a π←π transition is locally excited in the charged benzene or toluene molecule. On the basis of the positions of the CR-like bands, as well as the intensity of the LE band relative to that of homo-dimer ions, the probability of finding the charge on the benzene molecule is analyzed to be approximately 36%.

40 CFR 80.1270 - Who may generate benzene credits under the ABT program?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 17 2012-07-01 2012-07-01 false Who may generate benzene credits under... (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1270 Who may generate benzene credits under the ABT program? (a...

40 CFR 80.1270 - Who may generate benzene credits under the ABT program?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 17 2014-07-01 2014-07-01 false Who may generate benzene credits under... (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1270 Who may generate benzene credits under the ABT program? (a...

40 CFR 80.1270 - Who may generate benzene credits under the ABT program?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 17 2013-07-01 2013-07-01 false Who may generate benzene credits under... (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1270 Who may generate benzene credits under the ABT program? (a...

40 CFR 80.1270 - Who may generate benzene credits under the ABT program?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Who may generate benzene credits under... (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1270 Who may generate benzene credits under the ABT program? (a...

40 CFR 80.1270 - Who may generate benzene credits under the ABT program?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 16 2011-07-01 2011-07-01 false Who may generate benzene credits under... (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1270 Who may generate benzene credits under the ABT program? (a...

Reversible intermolecular energy transfer between saturated amines and benzene in non-polar solution

NASA Astrophysics Data System (ADS)

Halpern, Arthur M.; Wryzykowska, Krystyna

1981-01-01

Excitation of a mixture of dimethylethylamine (DEMA) and benzene in n-hexane at 222 nm primarily produces excited amine, while at 261 nm excited benzene predominantly results. The fluorescence spectra appreciably overlap. With 222 nm excitation, DEMA fluorescence is quenched by benzene at the diffusion-controlled rate; this quenching results with nearly unit efficiency in sensitized benzene fluorescence. With 261 nm excitation, some sensitized DEMA fluorescence is observed: the rate constant for tins process is ≈ 2.6 × 10 9 M -1 s -1.

Substrate Interactions during the Biodegradation of Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) Hydrocarbons by the Fungus Cladophialophora sp. Strain T1

PubMed Central

Prenafeta-Boldú, F. X.; Vervoort, J.; Grotenhuis, J. T. C.; van Groenestijn, J. W.

2002-01-01

The soil fungus Cladophialophora sp. strain T1 (= ATCC MYA-2335) was capable of growth on a model water-soluble fraction of gasoline that contained all six BTEX components (benzene, toluene, ethylbenzene, and the xylene isomers). Benzene was not metabolized, but the alkylated benzenes (toluene, ethylbenzene, and xylenes) were degraded by a combination of assimilation and cometabolism. Toluene and ethylbenzene were used as sources of carbon and energy, whereas the xylenes were cometabolized to different extents. o-Xylene and m-xylene were converted to phthalates as end metabolites; p-xylene was not degraded in complex BTEX mixtures but, in combination with toluene, appeared to be mineralized. The metabolic profiles and the inhibitory nature of the substrate interactions indicated that toluene, ethylbenzene, and xylene were degraded at the side chain by the same monooxygenase enzyme. Our findings suggest that soil fungi could contribute significantly to bioremediation of BTEX pollution. PMID:12039717

Why Is Benzene Unique? Screening Magnetic Properties of C6 H6 Isomers.

PubMed

Janda, Tomáš; Foroutan-Nejad, Cina

2018-05-25

Magnetic properties are commonly used to identify new aromatic molecules because it is generally believed that magnetization and energetic stability are correlated. To verify the potential correlation between the energy and magnetic response properties, we examined a set of 198 isomers of C 6 H 6 . The energy and magnetic properties of these molecules can be directly compared with no need to invoke any arbitrary reference state because the studied systems are all isomers. Benzene is the global minimum on the potential energy surface of C 6 H 6 , 35 kcal mol -1 lower in energy than the second most stable isomer, fulvene. Unlike its electronic energy, isotropic magnetizability of benzene is slightly lower than the average magnetizability of its isomers. Altogether, 44 isomers of C 6 H 6 were identified to have more negative magnetic susceptibility than benzene but were between 67.0 to 168.6 kcal mol -1 higher in energy than benzene. However, benzene is unique in two ways. Analyzing the paramagnetic contribution to the magnetic susceptibility as originally suggested by Bilde and Hansen (Mol. Phys., 1997, 92, 237) revealed that 53 molecules have lower paramagnetic susceptibility than benzene but among monocyclic systems benzene has the least paramagnetic susceptibility. Furthermore, benzene has the largest out-of-plane magnetic susceptibility that originates from the strongest ring current among all studied species. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Consistent Assignment of the Vibrations of Monohalosubstituted Benzenes

NASA Astrophysics Data System (ADS)

Harris, Joe; Andrejeva, Anna; Tuttle, William Duncan; Pugliesi, Igor; Schriever, Christian; Wright, Tim

2014-06-01

When substituted benzenes become a focus of a spectroscopic study there are various well known vibrational labelling schemes present, however it was shown in recent works the description of monohalobenzene vibrations in terms of benzene modes (ie. Wilson notation) is questionable in some cases. A new scheme is presented which uses the motions of monofluorobenzene vibrations as a basis for labelling vibrational assignments of monosubstituted benzenes.d The scheme has been successfully applied to the ground and excited states of toluene and its deuterated-methyl group isotopologue. Here we present the application of the scheme to fluorobenzene and its fully deuterated analogue. One-colour resonance-enhanced multiphoton ionization (REMPI) spectroscopy was employed in order to characterise the fluorobenzene and fluorobenzene-d5 excited state. E. B. Wilson Jr., Phys. Rev., 45, 706 (1934) G .Varsanyi, Assignments of the Vibrational Spectra of Seven Hundred Benzene Derivatives,Wiley, New York, 1974, Vol. I and II I. Pugliesi, N. C. Tonge and M. C. R. Cockett, J. Chem. Phys., 129, 104303 (2008) A. M. Gardner and T. G. Wright, J. Chem. Phys., 135,114305 (2011) A. M. Gardner, A. M. Green, V. M. Tame-Reyes, V. H. K. Wilton and T. G. Wright, 138, 134303 (2013) A. M. Gardner, A. M. Green, V. M. Tame-Reyes, K. L. Reid, J. A. Davies, V. H. K. Wilton and T. G. Wright, manuscript accepted

Differential susceptibility of rats and guinea pigs to the ototoxic effects of ethyl benzene.

PubMed

Cappaert, Natalie L M; Klis, Sjaak F L; Muijser, Hans; Kulig, Beverly M; Ravensberg, Luco C; Smoorenburg, Guido F

2002-01-01

The present study was designed to compare the ototoxic effects of volatile ethyl benzene in guinea pigs and rats. Rats showed deteriorated auditory thresholds in the mid-frequency range, based on electrocochleography, after 550-ppm ethyl benzene (8 h/day, 5 days). Outer hair cell (OHC) loss was found in the corresponding cochlear regions. In contrast, guinea pigs showed no threshold shifts and no OHC loss after exposure to much higher ethyl benzene levels (2500 ppm, 6 h/day, 5 days). Subsequently, a limited study (four rats and four guinea pigs) was performed in an attempt to understand these differences in susceptibility. Ethyl benzene concentration in blood was determined in both species after exposure to 500-ppm ethyl benzene (8 h/day, 3 days). At the end of the first day, blood of the rats contained 23.2+/-0.8-microg/ml ethyl benzene, whereas the concentration in guinea pig blood was 2.8+/-0.1 microg/ml. After 3 days, the concentration in both species decreased with respect to the first day, but the ethyl benzene concentration in rat blood was still 4.3 times higher than that in guinea pig blood. Thus, the difference in susceptibility between the species may be related to the ethyl benzene concentration in blood.

Ice growth from supercooled aqueous solutions of benzene, naphthalene, and phenanthrene.

PubMed

Liyana-Arachchi, Thilanga P; Valsaraj, Kalliat T; Hung, Francisco R

2012-08-23

Classical molecular dynamics (MD) were performed to investigate the growth of ice from supercooled aqueous solutions of benzene, naphthalene, or phenanthrene. The main objective of this study is to explore the fate of those aromatic molecules after freezing of the supercooled aqueous solutions, i.e., if these molecules become trapped inside the ice lattice or if they are displaced to the QLL or to the interface with air. Ice growth from supercooled aqueous solutions of benzene, naphthalene, or phenanthrene result in the formation of quasi-liquid layers (QLLs) at the air/ice interface that are thicker than those observed when pure supercooled water freezes. Naphthalene and phenanthrene molecules in the supercooled aqueous solutions are displaced to the air/ice interface during the freezing process at both 270 and 260 K; no incorporation of these aromatics into the ice lattice is observed throughout the freezing process. Similar trends were observed during freezing of supercooled aqueous solutions of benzene at 270 K. In contrast, a fraction of the benzene molecules become trapped inside the ice lattice during the freezing process at 260 K, with the rest of the benzene molecules being displaced to the air/ice interface. These results suggest that the size of the aromatic molecule in the supercooled aqueous solution is an important parameter in determining whether these molecules become trapped inside the ice crystals. Finally, we also report potential of mean force (PMF) calculations aimed at studying the adsorption of gas-phase benzene and phenanthrene on atmospheric air/ice interfaces. Our PMF calculations indicate the presence of deep free energy minima for both benzene and phenanthrene at the air/ice interface, with these molecules adopting a flat orientation at the air/ice interface.

Total cross sections for positron scattering from benzene, cyclohexane, and aniline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zecca, Antonio; Moser, Norberto; Perazzolli, Chiara

2007-08-15

We use a linear transmission technique to measure total cross sections for positron scattering from benzene, cyclohexane, and aniline. In the case of cyclohexane, the energy range of the present study is 0.1-20 eV, while for benzene and aniline it is 0.2-20 eV. With respect to benzene and cyclohexane, comparison is made to the only other existing results we know of [Makochekanwa and co-workers, Phys. Rev. A 68, 032707 (2003); 72, 042705 (2005)]. Agreement with those data is only marginal, being particularly poor at the overlap lower energies. Unlike Kimura et al. [J. Phys. B 37, 1461 (2004)], we findmore » the low-energy dependence of the positron-benzene total cross sections to be qualitatively similar to those found in the electron channel [Gulley et al., J. Phys. B 31, 2735 (1998)]. We believe that the present positron-aniline total cross sections represent the first time such data have been measured. These cross sections are almost identical to those we found for benzene, suggesting that substitution of hydrogen by the amine group on the aromatic ring is largely irrelevant to the scattering process in the energy regimes considered.« less

Reverse isotope dilution method for determining benzene and metabolites in tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bechtold, W.E.; Sabourin, P.J.; Henderson, R.F.

1988-07-01

A method utilizing reverse isotope dilution for the analysis of benzene and its organic soluble metabolites in tissues of rats and mice is presented. Tissues from rats and mice that had been exposed to radiolabeled benzene were extracted with ethyl acetate containing known, excess quantities of unlabeled benzene and metabolites. Butylated hydroxytoluene was added as an antioxidant. The ethyl acetate extracts were analyzed with semipreparative reversed-phase HPLC. Isolated peaks were collected and analyzed for radioactivity (by liquid scintillation spectrometry) and for mass (by UV absorption). The total amount of each compound present was calculated from the mass dilution of themore » radiolabeled isotope. This method has the advantages of high sensitivity, because of the high specific activity of benzene, and relative stability of the analyses, because of the addition of large amounts of unlabeled carrier analogue.« less

Benzene levels in ambient air and breath of smokers and nonsmokers in urban and pristine environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wester, R.C.; Maibach, H.I.; Gruenke, L.D.

Benzene levels in human breath and in ambient air were compared in the urban area of San Francisco (SF) and in a more remote coastal pristine setting of Stinson Beach, Calif. (SB). Benzene analysis was done by gas chromatography-mass spectroscopy (GC-MS). Ambient benzene levels were sevenfold higher in SF (2.6 +/- 1.3 ppb, n = 25) than SB (0.38 +/- 0.39 ppb, n = 21). In SF, benzene in smokers' breath (6.8 +/- 3.0 ppb) was greater than in nonsmokers' breath (2.5 +/- 0.8 ppb) and smokers' ambient air (3.3 +/- 0.8 ppb). In SB the same pattern was observed:more » benzene in smokers' breath was higher than in nonsmokers' breath and ambient air. Benzene in SF nonsmokers' breath was greater than in SB nonsmokers' breath. Marijuana-only smokers had benzene breath levels between those of smokers and nonsmokers. There was little correlation between benzene in breath and number of cigarettes smoked, or with other benzene exposures such as diet. Of special interest was the finding that benzene in breath of SF nonsmokers (2.5 +/- 0.8 ppb) was greater than that in nonsmokers ambient air (1.4 +/- 0.1 ppb). The same was true in SB, where benzene in nonsmokers breath was greater than ambient air (1.8 +/- 0.2 ppb versus 1.0 +/- 0.1 ppb on d 1 and 1.3 +/- 0.3 ppb versus 0.23 +/- 0.18 ppb on d 2). This suggests an additional source of benzene other than outdoor ambient air.« less

40 CFR 80.1220 - What are the implementation dates for the gasoline benzene program?

Code of Federal Regulations, 2011 CFR

2011-07-01

... the gasoline benzene program? 80.1220 Section 80.1220 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1220 What are the implementation dates for the gasoline benzene program...

40 CFR 80.1220 - What are the implementation dates for the gasoline benzene program?

Code of Federal Regulations, 2010 CFR

2010-07-01

... the gasoline benzene program? 80.1220 Section 80.1220 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1220 What are the implementation dates for the gasoline benzene program...

40 CFR 80.1356 - What are the attest engagement requirements for gasoline benzene compliance?

Code of Federal Regulations, 2011 CFR

2011-07-01

... requirements for gasoline benzene compliance? 80.1356 Section 80.1356 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Attest Engagements § 80.1356 What are the attest engagement requirements for gasoline benzene...

40 CFR 80.1356 - What are the attest engagement requirements for gasoline benzene compliance?

Code of Federal Regulations, 2010 CFR

2010-07-01

... requirements for gasoline benzene compliance? 80.1356 Section 80.1356 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Attest Engagements § 80.1356 What are the attest engagement requirements for gasoline benzene...

40 CFR 80.1356 - What are the attest engagement requirements for gasoline benzene compliance?

Code of Federal Regulations, 2014 CFR

2014-07-01

... requirements for gasoline benzene compliance? 80.1356 Section 80.1356 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Attest Engagements § 80.1356 What are the attest engagement requirements for gasoline benzene...

40 CFR 80.1220 - What are the implementation dates for the gasoline benzene program?

Code of Federal Regulations, 2014 CFR

2014-07-01

... the gasoline benzene program? 80.1220 Section 80.1220 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1220 What are the implementation dates for the gasoline benzene program...

40 CFR 80.1356 - What are the attest engagement requirements for gasoline benzene compliance?

Code of Federal Regulations, 2012 CFR

2012-07-01

... requirements for gasoline benzene compliance? 80.1356 Section 80.1356 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Attest Engagements § 80.1356 What are the attest engagement requirements for gasoline benzene...

40 CFR 80.1220 - What are the implementation dates for the gasoline benzene program?

Code of Federal Regulations, 2013 CFR

2013-07-01

... the gasoline benzene program? 80.1220 Section 80.1220 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1220 What are the implementation dates for the gasoline benzene program...

40 CFR 80.1356 - What are the attest engagement requirements for gasoline benzene compliance?

Code of Federal Regulations, 2013 CFR

2013-07-01

... requirements for gasoline benzene compliance? 80.1356 Section 80.1356 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Attest Engagements § 80.1356 What are the attest engagement requirements for gasoline benzene...

40 CFR 80.1220 - What are the implementation dates for the gasoline benzene program?

Code of Federal Regulations, 2012 CFR

2012-07-01

... the gasoline benzene program? 80.1220 Section 80.1220 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1220 What are the implementation dates for the gasoline benzene program...

SPECIES COMPARISON OF HEPATIC AND PULMONARY METABOLISM OF BENZENE. (R826191)

EPA Science Inventory

Abstract

Benzene is an occupational hazard and environmental toxicant found in cigarette smoke, gasoline, and the chemical industry. The major health concern associated with benzene exposure is leukemia. Studies using microsomal preparations from human, mouse, rabbit, ...

An analysis of historical exposures of pressmen to airborne benzene (1938-2006).

PubMed

Novick, Rachel M; Keenan, James J; Gross, Sherilyn A; Paustenbach, Dennis J

2013-07-01

Benzene is an aromatic hydrocarbon that, with sufficient cumulative lifetime doses, can cause acute myelogenous leukemia. Because of its volatility and solvent properties, it was used in the printing industry in inks, ink solvents, and cleaning agents from the 1930s to the 1970s. This analysis represents the first known attempt to gather and synthesize the available data on historical airborne benzene concentrations in printing facilities and exposures to pressmen. The sources of fugitive benzene vapors from printing operations have been identified as evaporation from ink fountains, exposed sections of the printing cylinder, the paper web, the paper post exit, and spilled ink. In addition, specific activities that could lead to benzene exposure, such as filling the fountains, using solvents to clean the press, and using solvents as personal cleaning agents, potentially occurred multiple times per work period. Eighteen studies were identified that reported workplace airborne concentrations in printing facilities between 1938 and 2006. Typical benzene air concentrations, considering both personal and area samples of various durations, were as high as 200 p.p.m. in the 1930s through the 1950s, 3-35 p.p.m. in the 1960s, 1.3-16 p.p.m. in the 1970s, 0.013-1 in the 1980s, and far less than 1 p.p.m. in the 1990s and 2000s. The decrease in benzene air concentrations by the late 1970s was likely to be linked to the decreased benzene content of printing materials, increased engineering controls, and to more stringent occupational exposure limits.

Outdoor and indoor benzene evaluation by GC-FID and GC-MS/MS.

PubMed

Sousa, José A; Domingues, Valentina F; Rosas, Mónica S; Ribeiro, Susana O; Alvim-Ferraz, Conceiçao M; Delerue-Matos, Cristina F

2011-01-01

The evaluation of benzene in different environments such as indoor (with and without tobacco smoke), a city area, countryside, gas stations and near exhaust pipes from cars running on different types of fuels was performed. The samples were analyzed using gas chromatography (GC) with flame ionization detection (FID) and tandem mass spectrometric detection (MS/MS) (to confirm the identification of benzene in the air samples). Operating conditions for the GC-MS analysis were optimized as well as the sampling and sample preparation. The results obtained in this work indicate that i) the type of fuel directly influences the benzene concentration in the air. Gasoline with additives provided the highest amount of benzene followed by unleaded gasoline and diesel; ii) the benzene concentration in the gas station was always higher than the advisable limit established by law (5 μg m⁻³) and during the unloading of gasoline the achieved concentration was 8371 μg m⁻³; iii) the data from the countryside (Taliscas) and the urban city (Matosinhos) were below 5 μg m⁻³ except 5 days after a fire on a petroleum refinery plant located near the city; iv) it was proven that in coffee shops where smoking is allowed the benzene concentration is higher (6 μg m⁻³) than in coffee shops where this is forbidden (4 μg m⁻³). This method may also be helpful for environmental analytical chemists who use GC-MS/MS for the confirmation or/and quantification of benzene.

Histone Deacetylase Inhibitors Trichostatin A and MCP30 Relieve Benzene-Induced Hematotoxicity via Restoring Topoisomerase IIα.

PubMed

Chen, Jingjing; Zheng, Zhouyi; Chen, Yi; Li, Jiaqi; Qian, Shanhu; Shi, Yifen; Sun, Lan; Han, Yixiang; Zhang, Shenghui; Yu, Kang

2016-01-01

Dysfunction of histone acetylation inhibits topoisomerase IIα (Topo IIα), which is implicated in benzene-induced hematotoxicity in patients with chronic benzene exposure. Whether histone deacetylase (HDAC) inhibitors can relieve benzene-induced hematotoxicity remains unclear. Here we showed that hydroquinone, a main metabolite of benzene, increased the HDAC activity, decreased the Topo IIα expression and induced apoptosis in human bone marrow mononuclear cells in vitro, and treatment with two HDAC inhibitors, namely trichostatin A (TSA) or a mixture of ribosome-inactivating proteins MCP30, almost completely reversed these effects. We further established a benzene poisoning murine model by inhaling benzene vapor in a container and found that benzene poisoning decreased the expression and activity of Topo IIα, and impaired acetylation of histone H4 and H3. The analysis of regulatory factors of Topo IIα promoter found that benzene poisoning decreased the mRNA levels of SP1 and C-MYB, and increased the mRNA level of SP3. Both TSA and MCP30 significantly enhanced the acetylation of histone H3 and H4 in Topo IIα promoter and increased the expression and activity of Topo IIα in benzene poisoning mice, which contributed to relieve the symptoms of hematotoxicity. Thus, treatment with HDAC inhibitors represents an attractive approach to reduce benzene-induced hematotoxicity.

29 CFR 1910.1028 - Benzene.

Code of Federal Regulations, 2014 CFR

2014-07-01

... any vessel or confined space where the benzene concentration might be high without proper safety... believe exposures are high, such as where tanks are opened, filled, unloaded or gauged; where containers... representative employee exposure for that operation during the shift on which the highest exposure is expected...

29 CFR 1910.1028 - Benzene.

Code of Federal Regulations, 2012 CFR

2012-07-01

... any vessel or confined space where the benzene concentration might be high without proper safety... believe exposures are high, such as where tanks are opened, filled, unloaded or gauged; where containers... representative employee exposure for that operation during the shift on which the highest exposure is expected...

29 CFR 1910.1028 - Benzene.

Code of Federal Regulations, 2011 CFR

2011-07-01

... any vessel or confined space where the benzene concentration might be high without proper safety... believe exposures are high, such as where tanks are opened, filled, unloaded or gauged; where containers... representative employee exposure for that operation during the shift on which the highest exposure is expected...

29 CFR 1910.1028 - Benzene.

Code of Federal Regulations, 2013 CFR

2013-07-01

... any vessel or confined space where the benzene concentration might be high without proper safety... believe exposures are high, such as where tanks are opened, filled, unloaded or gauged; where containers... representative employee exposure for that operation during the shift on which the highest exposure is expected...

Critical issues in benzene toxicity and metabolism: the effect of interactions with other organic chemicals on risk assessment.

PubMed

Medinsky, M A; Schlosser, P M; Bond, J A

1994-11-01

Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene are well documented and include aplastic anemia and pancytopenia. Some individuals exposed repeatedly to cytotoxic concentrations of benzene develop acute myeloblastic anemia. It has been hypothesized that metabolism of benzene is required for its toxicity, although administration of no single benzene metabolite duplicates the toxicity of benzene. Several investigators have demonstrated that a combination of metabolites (hydroquinone and phenol, for example) is necessary to duplicate the hematotoxic effect of benzene. Enzymes implicated in the metabolic activation of benzene and its metabolites include the cytochrome P450 monooxygenases and myeloperoxidase. Since benzene and its hydroxylated metabolites (phenol, hydroquinone, and catechol) are substrates for the same cytochrome P450 enzymes, competitive interactions among the metabolites are possible. In vivo data on metabolite formation by mice exposed to various benzene concentrations are consistent with competitive inhibition of phenol oxidation by benzene. Other organic molecules that are substrates for cytochrome P450 can inhibit the metabolism of benzene. For example, toluene has been shown to inhibit the oxidation of benzene in a noncompetitive manner. Enzyme inducers, such as ethanol, can alter the target tissue dosimetry of benzene metabolites by inducing enzymes responsible for oxidation reactions involved in benzene metabolism. The dosimetry of benzene and its metabolites in the target tissue, bone marrow, depends on the balance of activation processes, such as enzymatic oxidation, and deactivation processes, like conjugation and excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

40 CFR 80.1360 - Who is liable for violations under the gasoline benzene program?

Code of Federal Regulations, 2012 CFR

2012-07-01

... gasoline benzene program? 80.1360 Section 80.1360 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1360 Who is liable for violations under the gasoline benzene program? (a) The following...

40 CFR 80.1360 - Who is liable for violations under the gasoline benzene program?

Code of Federal Regulations, 2011 CFR

2011-07-01

... gasoline benzene program? 80.1360 Section 80.1360 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1360 Who is liable for violations under the gasoline benzene program? (a) The following...

40 CFR 80.1225 - Who must register with EPA under the gasoline benzene program?

Code of Federal Regulations, 2012 CFR

2012-07-01

... gasoline benzene program? 80.1225 Section 80.1225 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1225 Who must register with EPA under the gasoline benzene program? (a) Refiners and...

40 CFR 80.1360 - Who is liable for violations under the gasoline benzene program?

Code of Federal Regulations, 2013 CFR

2013-07-01

... gasoline benzene program? 80.1360 Section 80.1360 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1360 Who is liable for violations under the gasoline benzene program? (a) The following...

40 CFR 80.1360 - Who is liable for violations under the gasoline benzene program?

Code of Federal Regulations, 2010 CFR

2010-07-01

... gasoline benzene program? 80.1360 Section 80.1360 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1360 Who is liable for violations under the gasoline benzene program? (a) The following...

40 CFR 80.1225 - Who must register with EPA under the gasoline benzene program?

Code of Federal Regulations, 2013 CFR

2013-07-01

... gasoline benzene program? 80.1225 Section 80.1225 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1225 Who must register with EPA under the gasoline benzene program? (a) Refiners and...

40 CFR 80.1225 - Who must register with EPA under the gasoline benzene program?

Code of Federal Regulations, 2011 CFR

2011-07-01

... gasoline benzene program? 80.1225 Section 80.1225 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1225 Who must register with EPA under the gasoline benzene program? (a) Refiners and...

40 CFR 80.1225 - Who must register with EPA under the gasoline benzene program?

Code of Federal Regulations, 2010 CFR

2010-07-01

... gasoline benzene program? 80.1225 Section 80.1225 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1225 Who must register with EPA under the gasoline benzene program? (a) Refiners and...

40 CFR 80.1360 - Who is liable for violations under the gasoline benzene program?

Code of Federal Regulations, 2014 CFR

2014-07-01

... gasoline benzene program? 80.1360 Section 80.1360 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1360 Who is liable for violations under the gasoline benzene program? (a) The following...

40 CFR 80.1225 - Who must register with EPA under the gasoline benzene program?

Code of Federal Regulations, 2014 CFR

2014-07-01

... gasoline benzene program? 80.1225 Section 80.1225 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1225 Who must register with EPA under the gasoline benzene program? (a) Refiners and...

Antioxidant Compounds in Traditional Indian Pickles May Prevent the Process-Induced Formation of Benzene.

PubMed

Kharat, Mahesh M; Adiani, Vanshika; Variyar, Prasad; Sharma, Arun; Singhal, Rekha S

2016-01-01

Pickles in the Indian market contain ascorbic acid from the raw material used and benzoate as an added preservative that are involved in the formation of benzene in soft drinks. In this work, 24 market pickle samples were surveyed for benzene content, as well as its precursors and other constituents that influence its formation. The analysis showed that pickle samples were high in acid content (low pH) and showed significant amount of ascorbic acid, minerals (Cu and Fe), and benzoic acid present in them. Also, most samples exhibited high antioxidant activity that might be attributed to the ingredients used, such as fruits and spices. The solid-phase microextraction headspace gas chromatography-mass spectrometry method was developed in-house for benzene analysis. Eleven of 24 samples had benzene, with the highest concentration of 4.36 ± 0.82 μg of benzene per kg of pickle for a lime pickle that was also reported to have highest benzoic acid and considerably less hydroxyl radical ((•)OH) scavenging activity. However, benzene levels for all 11 samples were considerably below the World Health Organization regulatory limit of 10 μg/kg for benzene in mineral water. Studies on model systems revealed that the high antioxidant activity of Indian pickles may have had a strong inhibitory effect on benzene formation.

Production of Phenol from Benzene via Cumene

ERIC Educational Resources Information Center

Daniels, D. J.; And Others

1976-01-01

Describes an undergraduate chemistry laboratory experiment involving the production of phenol from benzene with the intermediate production of isopropylbenzene and isopropylbenzene hydroperoxide. (SL)

Antimalarial activity of compounds comprising a primary benzene sulfonamide fragment.

PubMed

Andrews, Katherine T; Fisher, Gillian M; Sumanadasa, Subathdrage D M; Skinner-Adams, Tina; Moeker, Janina; Lopez, Marie; Poulsen, Sally-Ann

2013-11-15

Despite the urgent need for effective antimalarial drugs with novel modes of action no new chemical class of antimalarial drug has been approved for use since 1996. To address this, we have used a rational approach to investigate compounds comprising the primary benzene sulfonamide fragment as a potential new antimalarial chemotype. We report the in vitro activity against Plasmodium falciparum drug sensitive (3D7) and resistant (Dd2) parasites for a panel of fourteen primary benzene sulfonamide compounds. Our findings provide a platform to support the further evaluation of primary benzene sulfonamides as a new antimalarial chemotype, including the identification of the target of these compounds in the parasite. Copyright © 2013 Elsevier Ltd. All rights reserved.

40 CFR 721.984 - Amino-hydroxy sulfonaphthylazo-disubstituted phenyl azo benzene carboxylate salt (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

...-disubstituted phenyl azo benzene carboxylate salt (generic). 721.984 Section 721.984 Protection of Environment...-disubstituted phenyl azo benzene carboxylate salt (generic). (a) Chemical substance and significant new uses...-disubstituted phenyl azo benzene carboxylate salt (PMN P-00-0351) is subject to reporting under this section for...

40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl sulfates...

40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl sulfates...

40 CFR 721.984 - Amino-hydroxy sulfonaphthylazo-disubstituted phenyl azo benzene carboxylate salt (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

...-disubstituted phenyl azo benzene carboxylate salt (generic). 721.984 Section 721.984 Protection of Environment...-disubstituted phenyl azo benzene carboxylate salt (generic). (a) Chemical substance and significant new uses...-disubstituted phenyl azo benzene carboxylate salt (PMN P-00-0351) is subject to reporting under this section for...

40 CFR 721.984 - Amino-hydroxy sulfonaphthylazo-disubstituted phenyl azo benzene carboxylate salt (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

...-disubstituted phenyl azo benzene carboxylate salt (generic). 721.984 Section 721.984 Protection of Environment...-disubstituted phenyl azo benzene carboxylate salt (generic). (a) Chemical substance and significant new uses...-disubstituted phenyl azo benzene carboxylate salt (PMN P-00-0351) is subject to reporting under this section for...

40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl sulfates...

40 CFR 721.984 - Amino-hydroxy sulfonaphthylazo-disubstituted phenyl azo benzene carboxylate salt (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

...-disubstituted phenyl azo benzene carboxylate salt (generic). 721.984 Section 721.984 Protection of Environment...-disubstituted phenyl azo benzene carboxylate salt (generic). (a) Chemical substance and significant new uses...-disubstituted phenyl azo benzene carboxylate salt (PMN P-00-0351) is subject to reporting under this section for...

40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl sulfates...

40 CFR 721.984 - Amino-hydroxy sulfonaphthylazo-disubstituted phenyl azo benzene carboxylate salt (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

...-disubstituted phenyl azo benzene carboxylate salt (generic). 721.984 Section 721.984 Protection of Environment...-disubstituted phenyl azo benzene carboxylate salt (generic). (a) Chemical substance and significant new uses...-disubstituted phenyl azo benzene carboxylate salt (PMN P-00-0351) is subject to reporting under this section for...

40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl sulfates...

Leukemia after exposure to benzene: temporal trends and implications for standards.

PubMed

Finkelstein, M M

2000-07-01

Benzene is a human leukemogen. Risk assessment, and the setting of occupational and environmental standards, has assumed that risk is constant in time after a unit of exposure. Leukemia risk is known to vary with time after exposure to ionizing radiation. A matched case-control study of leukemia risk in relation to the temporal pattern of benzene exposures was performed using data from the National Institute of Occupational Safety and Health. Leukemia risk following exposure to benzene varied with time in a manner similar to that following exposure to ionizing radiation. More recent exposures were more strongly associated with risk than were more distant ones. There was no significant relation between leukemia death and benzene exposures incurred more than 20 years previously. Recent analyses of specific occupational and environmental carcinogens, including benzene and radon, have indicated that cancer risk tends to decline as the time from exposure increases. This suggests that standards for the control of occupational or public risk must be selected to control exposures over a narrower time frame than the usual lifetime one. In the case of benzene, it would appear that risk is attributable primarily to exposures incurred during the previous 10 to 20 years, with exposures in the most recent 10 years being the most potent. To limit risk, exposures must be controlled during that interval. It is important that epidemiologists explore the temporal pattern of risk in their studies to facilitate the risk assessment of other carcinogens. Copyright 2000 Wiley-Liss, Inc.

Benzaldehyde in cherry flavour as a precursor of benzene formation in beverages.

PubMed

Loch, Christine; Reusch, Helmut; Ruge, Ingrid; Godelmann, Rolf; Pflaum, Tabea; Kuballa, Thomas; Schumacher, Sandra; Lachenmeier, Dirk W

2016-09-01

During sampling and analysis of alcohol-free beverages for food control purposes, a comparably high contamination of benzene (up to 4.6μg/L) has been detected in cherry-flavoured products, even when they were not preserved using benzoic acid (which is a known precursor of benzene formation). There has been some speculation in the literature that formation may occur from benzaldehyde, which is contained in natural and artificial cherry flavours. In this study, model experiments were able to confirm that benzaldehyde does indeed degrade to benzene under heating conditions, and especially in the presence of ascorbic acid. Analysis of a large collective of authentic beverages from the market (n=170) further confirmed that benzene content is significantly correlated to the presence of benzaldehyde (r=0.61, p<0.0001). In the case of cherry flavoured beverages, industrial best practices should include monitoring for benzene. Formulations containing either benzoic acid or benzaldehyde in combination with ascorbic acid should be avoided. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantum control of the normal modes of benzene with ultrafast laser pulses

NASA Astrophysics Data System (ADS)

Sauer, Petra; Dou, Yusheng; Torralva, Ben; Allen, Roland

2005-03-01

Remarkable innovations in laser technology have made it possible to create laser pulses with ultrashort durations (below 100 femtoseconds) and ultrahigh intensities (above 1 terawatt per cm^2). To understand the behavior of complex molecules and materials in this new regime of physics, chemistry, biology, and materials science requires innovative techniques which complement experiment and standard theory, and which can treat situations in which conventional approximations like the Born- Oppenheimer approximation, the Franck-Condon principle, and Fermi's golden rule are no longer valid. In this talk we describe a method that we are developing, semiclassical electron-radiation-ion dyanmics (SERID), which can be used to perform simulations of the coupled dynamics of electrons and nuclei in an intense radiation field. We have employed this technique in studying the normal modes of benzene, and the possibility of controlling these modes by optimizing the laser pulses that are applied to the molecule. Animations will be shown of particular normal modes, including the breathing and beating modes, illustrating their symmetries and other properties, and of the photodissociation of benzene when the laser pulse exceeds a threshold intensity.

Fusion of disubstituted benzenes.

PubMed

Martin, E; Yalkowsky, S H; Wells, J E

1979-05-01

The entropy of fusion of 84 disubstituted benzenes was essentially constant and independent of the participation of the compounds in intramolecular or intermolecular hydrogen bonding. It was also independent of the shapes, sizes, and dipole moments of the rigid molecules studied. While the entropy of fusion was independent of these parameters, the melting point and the heat of fusion showed a direct dependence on molecular properties.

Histone Deacetylase Inhibitors Trichostatin A and MCP30 Relieve Benzene-Induced Hematotoxicity via Restoring Topoisomerase IIα

PubMed Central

Chen, Yi; Li, Jiaqi; Qian, Shanhu; Shi, Yifen; Sun, Lan; Han, Yixiang; Zhang, Shenghui; Yu, Kang

2016-01-01

Dysfunction of histone acetylation inhibits topoisomerase IIα (Topo IIα), which is implicated in benzene-induced hematotoxicity in patients with chronic benzene exposure. Whether histone deacetylase (HDAC) inhibitors can relieve benzene-induced hematotoxicity remains unclear. Here we showed that hydroquinone, a main metabolite of benzene, increased the HDAC activity, decreased the Topo IIα expression and induced apoptosis in human bone marrow mononuclear cells in vitro, and treatment with two HDAC inhibitors, namely trichostatin A (TSA) or a mixture of ribosome-inactivating proteins MCP30, almost completely reversed these effects. We further established a benzene poisoning murine model by inhaling benzene vapor in a container and found that benzene poisoning decreased the expression and activity of Topo IIα, and impaired acetylation of histone H4 and H3. The analysis of regulatory factors of Topo IIα promoter found that benzene poisoning decreased the mRNA levels of SP1 and C-MYB, and increased the mRNA level of SP3. Both TSA and MCP30 significantly enhanced the acetylation of histone H3 and H4 in Topo IIα promoter and increased the expression and activity of Topo IIα in benzene poisoning mice, which contributed to relieve the symptoms of hematotoxicity. Thus, treatment with HDAC inhibitors represents an attractive approach to reduce benzene-induced hematotoxicity. PMID:27058040

Normal-phase liquid chromatography retention behavior of polycyclic aromatic hydrocarbon and their methyl-substituted derivatives on an aminopropyl stationary phase.

PubMed

Wilson, Walter B; Hayes, Hugh V; Sander, Lane C; Campiglia, Andres D; Wise, Stephen A

2017-09-01

Retention indices for 124 polycyclic aromatic hydrocarbons (PAHs) and 62 methyl-substituted (Me-) PAHs were determined using normal-phase liquid chromatography (NPLC) on a aminopropyl (NH 2 ) stationary phase. PAH retention behavior on the NH 2 phase is correlated to the total number of aromatic carbons in the PAH structure. Within an isomer group, non-planar isomers generally elute earlier than planar isomers. MePAHs generally elute slightly later but in the same region as the parent PAHs. Correlations between PAH retention behavior on the NH 2 phase and PAH thickness (T) values were investigated to determine the influence of non-planarity for isomeric PAHs with four to seven aromatic rings. Correlation coefficients ranged from r = 0.19 (five-ring peri-condensed molecular mass (MM) 252 Da) to r = -0.99 (five-ring cata-condensed MM 278 Da). In the case of the smaller PAHs (MM ≤ 252 Da), most of the PAHs had a planar structure and provided a low correlation. In the case of larger PAHs (MM ≥ 278 Da), nonplanarity had a significant influence on the retention behavior and good correlation between retention and T was obtained for the MM 278 Da, MM 302 Da, MM 328 Da, and MM 378 Da isomer sets. Graphical abstract NPLC separation of the three-, four-, five-, and six-ring PAH isomers with different number of aromatic carbon atoms and degrees of non-planarity (Thickness, T). The inserted figure plots the number of aromatic carbon atoms vs. the log I value for the 124 parent PAHs.