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1

Use of Mini-Sprinklers to Strip Trichloroethylene and Tetrachloroethylene from Contaminated Ground Water  

Microsoft Academic Search

Berisford, Y.C., P.B. Bush, J.I. Blake, and C.L. Bayer. 2003. Use of mini-sprinklers to strip trichloroethylene and tetrachloroethylene from contaminated ground water. J. Env. Qual. 32:801-815.;\\u000a;\\u000aThree low-volume mini-sprinklers were tested for their efficacy to strip trichloroethylene (TCE) and tetrachloroethylene (PCE) from water. Deionized water spiked with TCE and PCE was pumped through a mini-sprinkler supported on top of

Brerisford; C. Yvette; B. Parshall; John Blake; Cassandra L. Bayer

2003-01-01

2

Mechanism of Trichloroethylene Oxidation by Toluene Dioxygenase: Implications for Bioremediation.  

National Technical Information Service (NTIS)

The oxidation of trichloroethylene (TCE) by toluene dioxygenase in vivo and in vitro has been investigated. In a previous study, the initial rate of TCE oxidation by Pseudomonas putida Fl declined rapidly. This was shown in vivo, in the present study, to ...

L. P. Wackett

1991-01-01

3

Urinary excretion of total trichloro-compounds, trichloroethanol, and trichloroacetic acid as a measure of exposure to trichloroethylene and tetrachloroethylene  

PubMed Central

Ikeda, M., Ohtsuji, H., Imamura, T., and Komoike, Y. (1972).Brit. J. industr. Med.,29, 328-333. Urinary excretion of total trichloro-compounds, trichloroethanol, and trichloroacetic acid as a measure of exposure to trichloroethylene and tetrachloroethylene. To investigate the relation between trichloroethylene and tetrachloroethylene concentrations in working environments and metabolite concentrations in urine, a series of surveys was conducted at 17 workshops where the vapour concentration in the air of each workshop was relatively constant. Urine samples collected from 85 male workers were analysed for total trichloro-compounds (TTC), and trichloroacetic acid (TCA). Trichloroethanol (TCE) was estimated by difference. Statistical analyses of the data revealed that the urinary concentrations of both TTC and TCE were proportional to the atmospheric concentration of trichloroethylene. The concentration of TCA was also related to the vapour concentration up to 50 p.p.m. but not at higher concentrations. Further calculations suggested that only one-third of the trichloroethylene absorbed through the lungs was excreted in the urine during working time. In tetrachloroethylene exposure, urinary metabolite levels increased until the atmospheric concentration of the solvent reached 50 to 100 p.p.m., but little increase occurred at higher concentration. This observation was further confirmed by experimental exposure of rats. The toxicological significance of changes in the metabolism of the two solvents is discussed in relation to the possible necessity of reducing the threshold limit value from the current value of 100 p.p.m.

Ikeda, Masayuki; Ohtsuji, Hatsue; Imamura, Toshiko; Komoike, Yoshihiko

1972-01-01

4

Kinetic and isotope analyses of tetrachloroethylene and trichloroethylene degradation by model Fe(II)-bearing minerals.  

PubMed

The kinetics and in some cases stable carbon isotope fractionation associated with abiotic reductive dechlorination of tetrachloroethylene (PCE) and trichloroethylene (TCE) by model Fe(II)-bearing minerals present in anaerobic soils were measured. The minerals studied were chloride green rust (GR-Cl), sulfate green rust (GR-SO(4)), pyrite, magnetite, and adsorbed Fe(II) or FeS formed at the surface of goethite by treatment with dissolved Fe(II) or S(-II). We observed some abiotic transformation of PCE and TCE in every system studied, as evidenced by the presence of abiotic reaction products. Bulk enrichment factors (epsilon(bulk) values) for TCE transformation by GR-Cl and pyrite were -23.0+/-1.8 per thousand and -21.7+/-1.0 per thousand, respectively, which are more negative than reported values for microbial TCE dechlorination and could provide one means for distinguishing microbial from abiotic dechlorination of TCE in the environment. Considering the time scale of subsurface remediation technologies, including natural attenuation, minerals such as green rusts, pyrite, and magnetite have the potential to contribute to the transformation of PCE and TCE at contaminated sites. PMID:19111888

Liang, Xiaoming; Philp, R Paul; Butler, Elizabeth C

2008-12-27

5

Use of mini-sprinklers to strip trichloroethylene and tetrachloroethylene from contaminated ground water.  

PubMed

Three low-volume mini-sprinklers were tested for their efficacy to strip trichloroethylene (TCE) and tetrachloroethylene (PCE) from water. Deionized water spiked with TCE and PCE was pumped for approximately 1 h at 0.19 to 0.21 MPa (28 to 30 lb in(-2)) through a mini-sprinkler supported on top of a 1.8-m-tall riser. Water was collected in collection vessels at 0.61 and 1.22 m above the ground on support columns that were spaced at 0.61-m intervals from the riser base, and samples were composited per height and distance from the riser. Overall, air-stripping reduced dissolved concentrations of TCE and PCE by 99.1 to 100 and 96.9 to 100%, respectively, from mean influent dissolved concentrations of 466 to 1675 microg L(-1) TCE and 206 to 940 microg L(-1) PCE. In terms of mass removed, the mini-sprinklers removed TCE and PCE at a rate of approximately 1400 to 1700 and 700 to 900 microg L(-1), respectively, over a 1-h test period. Mini-sprinklers offer the advantages of (i) easy setup in series that can be used on practically any terrain; (ii) operation over a long period of time that does not threaten aquifer depletion; (iii) use in small or confined aquifers in which the capacity is too low to support large irrigation or purging systems; and (iv) use in forests in which the small, low-impact droplets of the mini-sprinklers do not damage bark and in which trees can help manage (via evapotranspiration) excess waste water. PMID:12809281

Berisford, Yvette C; Bush, Parshall B; Blake, John I; Bayer, Cassandra L

6

Kinetics of the transformation of trichloroethylene and tetrachloroethylene by iron sulfide  

SciTech Connect

The transformation of trichloroethylene (TCE), tetrachloroethylene (PCE), and 1,1-dichloroethylene FeS in aqueous solution at pH 8.3 was studied in batch experiments. TCE and PCE were transformed by FeS with pseudo-first-order rate constants, corrected for partitioning to the sample headspace, of (1.49 [+-] 0.14) [times] 10[sup [minus]3] h[sup [minus]1] (TCE) and (5.7 [+-] 1.0) [times] 10[sup [minus]4] h[sup [minus]1] (PCE). A 17% decrease in the concentration of 1,3-DCE was observed over 120 days; however, no reaction products were detected. TCE and PCE transformation data were fit to a rate law assuming transformation of TCE via parallel reaction pathways to acetylene and cis-1,2-dichloroethylene (cis-DCE) and transformation of PCE via parallel reaction pathways to acetylene and TCE. Acetylene was the major reaction product for both TCE and PCE. Determination of rate constants for each reaction pathway indicated that TCE was transformed to acetylene 11.8 [+-] 1.1 times faster than to cis-DCE and that PCE was transformed to acetylene 8.2 [+-] 1.8 times faster than to TCE. Additional minor reaction products were vinyl chloride (VC) for TCE and cis-DCE for PCE. Detection of acetylene as the major product of both TCE and PCE transformation by FeS contrasts with the sequential hydrogenolysis products typically observed in the microbial transformation of these compounds, making acetylene a potential indicator of abiotic transformation of TCE and PCE by FeS in natural systems.

Butler, E.C.; Hayes, K.F. (Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Civil and Environmental Engineering)

1999-06-15

7

Trichloroethylene oxidation by purified toluene 2-monooxygenase: products, kinetics, and turnover-dependent inactivation.  

PubMed Central

Trichloroethylene is oxidized by several types of nonspecific bacterial oxygenases. Toluene 2-monooxygenase from Burkholderia cepacia G4 is implicated in trichloroethylene oxidation and is uniquely suggested to be resistant to turnover-dependent inactivation in vivo. In this work, the oxidation of trichloroethylene was studied with purified toluene 2-monooxygenase. All three purified toluene 2-monooxygenase protein components and NADH were required to reconstitute full trichloroethylene oxidation activity in vitro. The apparent Km and Vmax were 12 microM and 37 nmol per min per mg of hydroxylase component, respectively. Ten percent of the full activity was obtained when the small-molecular-weight enzyme component was omitted. The stable oxidation products, accounting for 84% of the trichloroethylene oxidized, were carbon monoxide, formic acid, glyoxylic acid, and covalently modified oxygenase proteins that constituted 12% of the reacted [14C]trichloroethylene. The stable oxidation products may all derive from the unstable intermediate trichloroethylene epoxide that was trapped by reaction with 4-(p-nitrobenzyl)pyridine. Chloral hydrate and dichloroacetic acid were not detected. This finding differs from that with soluble methane monooxygenase and cytochrome P-450 monooxygenase, which produce chloral hydrate. Trichloroethylene-dependent inactivation of toluene 2-monooxygenase activity was observed. All of the protein components were covalently modified during the oxidation of trichloroethylene. The addition of cysteine to reaction mixtures partially protected the enzyme system against inactivation, most notably protecting the NADH-oxidoreductase component. This suggested the participation of diffusible intermediates in the inactivation of the oxidoreductase.

Newman, L M; Wackett, L P

1997-01-01

8

Trichloroethylene (TCE) and toluene effects on the structure and function of the soil community  

Microsoft Academic Search

The effects of trichloroethylene (TCE) and toluene on indigenous soil communities were examined in soil microcosms, with special emphasis on community structure and function. Soil communities were exposed to TCE (1, 30 and 60 ?g ml?1) plus toluene (20 ?g ml?1), TCE only (1, 30 and 60 ?g ml?1), and toluene only (20, 60, 100 and 200 ?g ml?1) (all

Mark E. Fuller; Kate M. Scow; Sean Lau; Howard Ferris

1997-01-01

9

Assessing interaction thresholds for trichloroethylene in combination with tetrachloroethylene and 1,1,1-trichloroethane using gas uptake studies and PBPK modeling  

Microsoft Academic Search

The volatile organic solvents trichloroethylene (TCE), tetrachloroethylene (perchloroethylene, PERC), and 1,1,1-trichloroethane (methylchloroform, MC) are widely distributed environmental pollutants and common contaminants of many chemical waste sites. To investigate the mode of pharmacokinetic interactions among TCE, PERC, and MC and to calculate defined \\

Ivan D. Dobrev; Melvin E. Andersen; Raymond S. Yang

2001-01-01

10

Novel Pathway of Toluene Catabolism in the Trichloroethylene-Degrading Bacterium G4  

PubMed Central

o-Cresol and 3-methylcatechol were identified as successive transitory intermediates of toluene catabolism by the trichloroethylene-degrading bacterium G4. The absence of a toluene dihydrodiol intermediate or toluene dioxygenase and toluene dihydrodiol dehydrogenase activities suggested that G4 catabolizes toluene by a unique pathway. Formation of a hybrid species of 18O- and 16O-labeled 3-methylcatechol from toluene in an atmosphere of 18O2 and 16O2 established that G4 catabolizes toluene by successive monooxygenations at the ortho and meta positions. Detection of trace amounts of 4-methylcatechol from toluene catabolism suggested that the initial hydroxylation of toluene was not exclusively at the ortho position. Further catabolism of 3-methylcatechol was found to proceed via catechol-2,3-dioxygenase and hydroxymuconic semialdehyde hydrolase activities.

Shields, Malcolm S.; Montgomery, Stacy O.; Chapman, Peter J.; Cuskey, Stephen M.; Pritchard, P. H.

1989-01-01

11

Biodegradation of trichloroethylene and toluene by indigenous microbial populations in vadose sediments  

Microsoft Academic Search

The unsaturated subsurface (vadose zone) receives significant amounts of hazardous chemicals, yet little is known about its microbial communities and their capacity to biodegrade pollutants. Trichloroethylene (TCE) biodegradation occurs readily in surface soils; however, the process usually requires enzyme induction by aromatic compounds, methane, or other cosubstrates. The aerobic biodegradation of toluene and TCE by indigenous microbial populations was measured

M. E. Fuller; D. Y. Mu; K. M. Scow

1995-01-01

12

Cometabolic degradation of trichloroethylene in a hollow fiber membrane reactor with toluene as a substrate  

Microsoft Academic Search

Contamination of air by volatile organic components (VOCs) is a serious health concern in the present industrial age. To address this issue, a study was devoted to the development of a hollow fiber membrane bioreactor (HMBR), where microorganisms immobilized on the outside of a polyvinylidene fluoride (PVDF) membrane contribute to removing toluene and trichloroethylene (TCE) from air passing through the

Ya Zhao; Zhijun Liu; Fengxia Liu; Zhiyi Li

2011-01-01

13

Reductive dechlorination of tetrachloroethylene and trichloroethylene catalyzed by vitamin B{sub 12} in homogeneous and heterogeneous systems  

SciTech Connect

The reduction of tetrachloroethylene (PCE) and trichloroethylene (TCE) catalyzed by vitamin B{sub 12} was examined in homogeneous and heterogeneous (B{sub 12} bound to agarose) batch systems using titanium(III) citrate as the bulk reductant. The solution and surface-mediated reaction rates at similar B{sub 12} loadings were comparable, indicating that binding vitamin B{sub 12} to a surface did not lower catalytic activity. No loss in PCE reducing activity was observed with repeated usage of surface-bound vitamin B{sub 12}. Carbon mass recoveries were 81-84% for PCE reduction and 89% for TCE reduction, relative to controls. In addition to sequential hydrogenolysis, a second competing reaction mechanism for the reduction of PCE and TCE by B{sub 12}, reductive {beta}-elimination, is proposed to account for the observation of acetylene as a significant reaction intermediate. Reductive {beta}-elimination should be considered as a potential pathway in other reactive systems involving the reduction of vicinal polyhaloethenes. Surface-bound catalysts such as vitamin B{sub 12} may have utility in the engineered degradation of aqueous phase chlorinated ethenes. 19 refs., 6 figs., 1 tab.

Burris, D.R.; Smith, M.H. [Armstrong Lab., Tyndall Air Force Base, FL (United States); Delcomyn, C.A. [Applied Research Associates, Inc., Tyndall Air Force Base, FL (United States); Roberts, A.L. [Johns Hopkins Univ., Baltimore, MD (United States)

1996-10-01

14

Trichloroethylene removal and oxidation toxicity mediated by toluene dioxygenase of Pseudomonas putida.  

PubMed Central

Whole cells of Pseudomonas putida containing toluene dioxygenase were able to remove all detectable trichloroethylene (TCE) from assay mixtures. The capacity of cells to remove TCE was 77 microM/mg of protein with an initial rate of removal of 5.2 nmol/min/ng of protein. TCE oxidation resulted in a decrease in the growth rate of cultures and caused rapid cell death. Addition of dithiothreitol to assay mixtures increased the TCE removal capacity of cells by up to 67% but did not prevent TCE-mediated cell death. TCE induced toluene degradation by whole cells to a rate approximately 40% of that induced by toluene itself.

Heald, S; Jenkins, R O

1994-01-01

15

Recruitment and expression of toluene/trichloroethylene biodegradation genes in bacteria native to deep-subsurface sediments  

SciTech Connect

Four plasmids, each encoding a combination of either an Escherichia coli or Pseudomonas putida promoter and either toluene dioxygenase or toluene monooxygenase, were electroporated into five bacterial strains isolated from sediments found at depths of 91 to 295 m. Four of these engineered bacterial strains demonstrated both toluene and trichloroethylene degradation activities. 26 refs., 2 tabs.

Romine, M.F.; Brockman, F.J. [Pacific Northwest National Lab., Richland, WA (United States)

1996-07-01

16

Kinetic analysis of a tod-lux bacterial reporter for toluene degradation and trichloroethylene cometabolism.  

PubMed

Kinetics of toluene and trichloroethylene (TCE) degradation and bioluminescence from the bioreporter Pseudomonas putida B2 and TVA8 were investigated utilizing batch and continuous culture, respectively. Degradation was modeled using a Michaelis-Menten expression for the competition of two substrates for a single enzyme system, and bioluminescence was modeled assuming a luciferase enzyme saturational dependence on toluene as the inducer and growth substrate. During the batch experiments, bioluminescence increased at approximately 90 namp/min for initial toluene concentrations of 10 to 50 mg/L, but more slowly at higher toluene concentrations, suggesting maximum promoter induction at below 10 mg/L and toxic effects above 50 mg/L toluene. TCE degradation did not occur until toluene depletion, presumably due to competition between toluene and TCE for the toluene dioxygenase enzyme. During continuous culture, bioluminescence transiently increased, then gradually decreased in response to increasing step changes in toluene feed concentration. Bioluminescence in the CSTR appeared to be limited by growth substrate and/or inducer. PMID:10861405

Kelly, C J; Bienkowski, P R; Sayler, G S

2000-08-01

17

Effect of trichloroethylene (TCE) and toluene concentrations on TCE and toluene biodegradation and the population density of TCE and toluene degraders in soil  

SciTech Connect

Toluene is one of several cosubstrates able to support the cometabolism of trichloroethylene (TCE) by soil microbial communities. Indigenous microbial populations in soil degraded TCE in the presence, but not the absence, of toluene after a 60- to 80-h lag period. Initial populations of toluene and TCE degraders ranged from 0.2 x 10{sup 3} to 4 x 10{sup 3} cells per g of soil and increased by more than 4 orders of magnitude after the addition of 20 {mu}g of toluene and 1 {mu}g of TCE per mol of soil solution. The numbers of TCE and toluene degraders and the percent removal of TCE increased with an increase in initial toluene concentration. As the initial TCE concentration was increased from 1 to 20 {mu}g/ml, the numbers of toluene and TCE degraders and the rate of toluene degradation decreased, and no TCE degradation occurred. No toluene or TCE degradation occurred at a TCE concentration of 50 {mu}g/ml. 22 refs., 3 figs., 2 tabs.

Mu, D.Y.; Scow, K.M. [Univ. of California, Davis, CA (United States)

1994-07-01

18

Changes in soil microbial community composition induced by cometabolism of toluene and trichloroethylene  

Microsoft Academic Search

The effects of trichloroethylene (TCE) on microbial community composition were analyzed by reverse sample genome probing. Soil enrichments were incubated in dessicators containing an organic phase of either 1 or 10% (w\\/w) toluene in vacuum pump oil, delivering constant equilibrium aqueous concentrations of 16 and 143?mg\\/l, respectively. Increasing the equilibrium aqueous concentration of TCE from 0 to 10?mg\\/l led to

Casey Hubert; Yin Shen; Gerrit Voordouw

2005-01-01

19

Kinetics of trichloroethylene cometabolism and toluene biodegradation: Model application to soil batch experiments  

SciTech Connect

Trichloroethylene (TCE) biodegradation in soil under aerobic conditions requires the presence of another compound, such as toluene, to support growth of microbial populations and enzyme induction. The biodegradation kinetics of TCE and toluene were examined by conducting three groups of experiments in soil: toluene only, toluene combined with low TCE concentrations, and toluene with TCE concentrations similar to or higher than toluene. The biodegradation of TCE and toluene and their interrelationships were modeled using a combination of several biodegradation functions. In the model, the pollutants were described as existing in the solid, liquid, and gas phases of soil, with biodegradation occurring only in the liquid phase. The distribution of the chemicals between the solid and liquid phase was described by a linear sorption isotherm, whereas liquid-vapor partitioning was described by Henry's law. Results from 12 experiments with toluene only could be described by a single set of kinetic parameters. The same set of parameters could describe toluene degradation in 10 experiments where low TCE concentrations were present. From these 10 experiments a set of parameters describing TCE cometabolism induced by toluene also was obtained. The complete set of parameters was used to describe the biodegradation of both compounds in 15 additional experiments, where significant TCE toxicity and inhibition effects were expected. Toluene parameters were similar to values reported for pure culture systems. Parameters describing the interaction of TCE with toluene and biomass were different from reported values for pure cultures, suggesting that the presence of soil may have affected the cometabolic ability of the indigenous soil microbial populations.

El-Farhan, Y.H.; Scow, K.M.; Fan, S.; Rolston, D.E.

2000-06-01

20

Aerobic degradation of tetrachloroethylene by toluene-o-xylene monooxygenase of Pseudomonas stutzeri OX1  

Microsoft Academic Search

Tetrachloroethylene (PCE) is thought to have no natural source, so it is one of the most difficult contaminants to degrade biologically. This common groundwater pollutant was thought completely nonbiodegradable in the presence of oxygen. Here we report that the wastewater bacterium Pseudomonas stutzeri OX1 degrades aerobically 0.56 ?mol of 2.0 ?mol PCE in 21 h (Vmax ? 2.5 nmol min?1

Doohyun Ryoo; Hojae Shim; Paola Barbieri; Thomas K. Wood

2000-01-01

21

Comparison of factors influencing trichloroethylene degradation by toluene-oxidizing bacteria.  

PubMed Central

The degradation of trichloroethylene (TCE) by toluene-oxidizing bacteria has been extensively studied, and yet the influence of environmental conditions and physiological characteristics of individual strains has received little attention. To consider these effects, the levels of TCE degradation by strains distinguishable on the basis of toluene and nitrate metabolism were compared under aerobic or hypoxic conditions in the presence and absence of nitrate and an exogenous electron donor, lactate. Under aerobic conditions with toluene-induced cells, strains expressing toluene dioxygenases (Pseudomonas putida F1, Pseudomonas sp. strain JS150, Pseudomonas fluorescens CFS215, and Pseudomonas sp. strain W31) degraded TCE at low rates, with less than 12% of the TCE removed in 18 h. In contrast, strains expressing toluene monooxygenases (Burkholderia cepacia G4, Burkholderia pickettii PKO1, and Pseudomonas mendocina KR1) degraded 36 to 67% of the TCE over the same period. Under hypoxic conditions (1.7 mg of dissolved oxygen per liter) or when lactate was added as an electron donor, the extent of TCE degradation by toluene-induced cells was generally lower. In the presence of lactate, degradation of TCE by denitrifying strain PKO1 was enhanced by nitrate under conditions in which dissimilatory nitrate reduction was observed. The results of experiments performed with strains F1, G4, PKO1, and KR1 suggested that TCE or an oxidation product induces toluene degradation and that TCE induces its own degradation in the monooxygenase strains. The role of TCE as an inducer of toluene oxygenase activity in PKO1 was confirmed by performing a promoter probe analysis, in which we found that TCE activates transcription from the PKO1 3-monooxygenase operon promoter.

Leahy, J G; Byrne, A M; Olsen, R H

1996-01-01

22

Heterogeneous Photocatalytic Oxidation of Trichloroethylene and Toluene Mixtures in Air: Kinetic Promotion and Inhibition, Time-Dependent Catalyst Activity  

Microsoft Academic Search

Photocatalyzed degradation of trace level trichloroethylene (TCE) and toluene in air were carried out over near-UV-illuminated titanium dioxide (anatase) powder in a flow reactor using a residence time of about 5–6 ms. Concentration ranges for TCE and toluene were 0–800 mg\\/m3. TCE photooxidation was very rapid under our experimental conditions, and ?100% conversion was achieved for TCE concentration examined up

Yang Luo; David F. Ollis

1996-01-01

23

Experiments and three phase modelling of a biofilter for the removal of toluene and trichloroethylene.  

PubMed

Volatile organic compounds, namely, toluene, trichloroethylene, styrene, etc., disposed off by electronics and polymer industries, are very harmful. The treatment of VOC laden air through biochemical route is one of the potential options for reduction of their concentration in parts per million or parts per billion level. Under the present investigation, a 0.05-m diameter and 0.58-m high trickle bed biofilter has been studied for the removal of VOCs namely toluene and trichloroethylene from a simulated air-VOC mixture using pure strain of Pseudomonas putida (NCIM2650) in immobilized form. Inlet concentrations of VOCs have been varied in two ranges, the lower being 0.20-2.00 g/m(3) and higher being 10-20 g/m(3), respectively. The Monod type rate kinetics of removal of VOCs has been determined. A three-phase deterministic mathematical model has been developed taking the simultaneous reaction kinetics and interphase (gas to liquid to biofilm) mass transfer rate of VOCs into consideration. Experimentally determined kinetic parameters and mass transfer coefficients calculated using standard correlations have been used. Concentrations have been simulated for all the three phases. Simulated results based on the model have been compared with the experimental ones for both gas and liquid phases satisfactorily. The mathematical model validated through the successful comparison with experimental data may be utilized for the prediction of performance of biofilters undergoing removal of different VOCs in any further investigation and may be utilized for the scale-up of the system to industrial scale. PMID:21170726

Das, Chhaya; Chowdhury, Ranjana; Bhattacharya, Pinaki

2010-12-19

24

Oxidation of trichloroethylene, 1,1-dichloroethylene, and chloroform by toluene\\/o-xylene monooxygenase from Pseudomonas stutzeri OX1  

Microsoft Academic Search

Toluene\\/o-xylene monooxygenase (ToMO) from Pseudomonas stutzeri OX1, which oxidizes toluene and o-xylene, was examined for its ability to degrade the environmental pollutants trichloroethylene (TCE), 1,1-dichloroethylene (1,1-DCE), cis-1,2-DCE, trans-1,2-DCE, chloroform, dichloromethane, phenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, 2,3,5,6-tetrachlorophenol, and 2,3,4,5,6-pentachlorophenol. Escherichia coli JM109 that expressed ToMO from genes on plasmid pBZ1260 under control of the lac promoter degraded TCE, 1,1-DCE, and chloroform at

SADHANA CHAUHAN; T. K. Wood; P. Barbieri

1998-01-01

25

Rhizoremediation of Trichloroethylene by a Recombinant, Root-Colonizing Pseudomonas fluorescens Strain Expressing Toluene ortho-Monooxygenase Constitutively  

Microsoft Academic Search

Trichloroethylene (TCE) was removed from soils by using a wheat rhizosphere established by coating seeds with a recombinant, TCE-degrading Pseudomonas fluorescens strain that expresses the tomA1 (toluene o-mono- oxygenase) genes from Burkholderia cepacia PR123(TOM23C). A transposon integration vector was used to insert tomA1 into the chromosome of P. fluorescens 2-79, producing a stable strain that expressed constitutively the monooxygenase at

DENNIS C. YEE; JENNIFER A. MAYNARD; THOMAS K. WOOD

1998-01-01

26

Oxidation of trichloroethylene, 1,1-dichloroethylene, and chloroform by toluene/o-xylene monooxygenase from Pseudomonas stutzeri OX1  

SciTech Connect

Toluene/o-xylene monooxygenase (ToMO) from Pseudomonas stutzeri OX1, which oxidizes toluene and o-xylene, was examined for its ability to degrade the environmental pollutants trichloroethylene (TCE), 1,1-dichloroethylene (1,1-DCE), cis-1,2-DCE, trans-1,2-DCE, chloroform, dichloromethane, phenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, 2,3,5,6-tetrachlorophenol, and 2,3,4,5,6-pentachlorophenol. Escherichia coli JM109 that expressed ToMO from genes on plasmid pBZ1260 under control of the lac promoter degraded TCE, 1,1-DCE, and chloroform at initial rates of 3.1, 3.6, and 1.6 nmol, respectively. Stoichiometric amounts of chloride release were seen, indicating mineralization. Thus, the substrate range of ToMO is extended to include aliphatic chlorinated compounds.

Chauhan, S.; Wood, T.K. [Univ. of California, Irvine, CA (United States). Dept. of Chemical and Biochemical Engineering; Barbieri, P. [Univ. degli Studi di Milano, Milan (Italy). Dept. di Genetica e di Biologia dei Microrganismi

1998-08-01

27

Modeling trichloroethylene degradation by a recombinant pseudomonad expressing toluene ortho-monooxygenase in a fixed-film bioreactor  

SciTech Connect

Burkholderia cepacia PR1{sub 23}(TOM{sub 23C}), expressing constitutively the TCE-degrading enzyme toluene ortho-monooxygenase (Tom), was immobilized on SIRAN{trademark} glass beads in a biofilter for the degradation and mineralization of gas-phase trichloroethylene (TCE). To interpret the experimental results, a mathematical model has been developed which includes axial dispersion, convection, film mass-transfer, and biodegradation coupled with deactivation of the TCE-degrading enzyme. Parameters used for numerical simulation were determined from either independent experiments or values reported in the literature. The model was compared with the experimental data, and there was good agreement between the predicted and measured TCE breakthrough curves. The simulations indicated that TCE degradation in the biofilter was not limited by mass transfer of TCE or oxygen from the gas phase to the liquid/biofilm phase (biodegradation limits), and predicts that improving the specific TCE degradation rates of bacteria will not significantly enhance long-term biofilter performance. The most important factors for prolonging the performance of biofilter are increasing the amount of active biomass and the transformation capacity enhancing resistance to TCE metabolism.

Sun, A.K.; Hong, J.; Wood, T.K. [Univ. of California, Irvine, CA (United States). Dept. of Chemical and Biochemical Engineering

1998-07-05

28

Rhizoremediation of Trichloroethylene by a Recombinant, Root-Colonizing Pseudomonas fluorescens Strain Expressing Toluene ortho-Monooxygenase Constitutively  

PubMed Central

Trichloroethylene (TCE) was removed from soils by using a wheat rhizosphere established by coating seeds with a recombinant, TCE-degrading Pseudomonas fluorescens strain that expresses the tomA+ (toluene o-monooxygenase) genes from Burkholderia cepacia PR123(TOM23C). A transposon integration vector was used to insert tomA+ into the chromosome of P. fluorescens 2-79, producing a stable strain that expressed constitutively the monooxygenase at a level of 1.1 nmol/min · mg of protein (initial TCE concentration, 10 ?M, assuming that all of the TCE was in the liquid) for more than 280 cell generations (36 days). We also constructed a salicylate-inducible P. fluorescens strain that degraded TCE at an initial rate of 2.6 nmol/min · mg of protein in the presence of 10 ?M TCE [cf. B. cepacia G4 PR123(TOM23C), which degraded TCE at an initial rate of 2.5 nmol/min · mg of protein]. A constitutive strain, P. fluorescens 2-79TOM, grew (maximum specific growth rate, 0.78 h?1) and colonized wheat (3 × 106 CFU/cm of root) as well as wild-type P. fluorescens 2-79 (maximum specific growth rate, 0.77 h?1; level of colonization, 4 × 106 CFU/cm of root). Rhizoremediation of TCE was demonstrated by using microcosms containing the constitutive monooxygenase-expressing microorganism, soil, and wheat. These closed microcosms degraded an average of 63% of the initial TCE in 4 days (20.6 nmol of TCE/day · plant), compared to the 9% of the initial TCE removed by negative controls consisting of microcosms containing wild-type P. fluorescens 2-79-inoculated wheat, uninoculated wheat, or sterile soil.

Yee, Dennis C.; Maynard, Jennifer A.; Wood, Thomas K.

1998-01-01

29

[Effects of benzene, toluene on reductive dechlorination of trichloroethylene and its daughter product cis-1,2-dichloroethylene by granular iron].  

PubMed

Mixed plumes contained chlorinated solvents and petroleum hydrocarbons which mainly refers to BTEX (benzene, toluene, ethylbenzene and xylenes) in groundwater can be remediated by sequential units combined an iron permeable reactive barrier (Fe0-PRB) with an anoxic wall. In design of the Fe0-PRB it should be taken into account the necessity of altering the width of the iron cell in the presence of BTEX. Three column experiments were conducted to evaluate the effects of benzene, toluene on the long-term performance of reductive dechlorination of trichloroethylene (TCE) by granular iron. The results showed that the kinetics of TCE (at the initial concentration of 2 mg x L(-1) more or less) reduction was accorded with pseudo first-order even in the presence of benzene or toluene (at about 1-2 mg x L(-1), respectively). The existence of benzene and toluene inhibited the removal of TCE by 15.1% and 18. 5% , respectively; however, the presence of benzene slightly increased cis-1,2-DCE reduction rate by 4.5%, and the presence of toluene increased cis-1,2-DCE reduction rate by 42.8%. The inhibition of benzene and toluene other than mineral precipitates was not one of the decisive factors in the long-term performance of an Feo-PRB; in addition, the kinds of chlorinated daughter products of TCE in the presence/absence of benzene or toluene were identical and cis-1,2-dichloroethylene (cis-1,2-DCE), the major intermediate, firstly broke through from all the 3 columns at concentrations about 2-75 microg x L(-1), indicating that designing the width of an Fe0-PRB should be based on the hydraulic residence time of cis-1,2-DCE. In conclusion, if only considering the TCE remedial goals and disregarding the effects of cis-1,2-DCE on BTEX biodegradation downgradient the Fe0-PRB, the results suggested that it should be not necessary to increase the width of the iron cell for constructing sequential permeable reactive barriers (SPRBs) to rescue TCE- and BTEX-contaminated aquifers. PMID:20825021

Liu, Yu-long; Xia, Fan; Liu, Fei; Chen, Hong-han

2010-07-01

30

Leaching of tetrachloroethylene from vinyl-lined pipe  

Microsoft Academic Search

Tetrachloroethylene has been used in the manufacture of vinyl-lined asbestos cement pipe installed in water distribution systems in certain New England communities. Tetrachloroethylene was used as a solvent for Piccotex, a vinyl-toluene ..cap alpha..-methyl styrene co-polymer, which was then sprayed on the interior of the finished asbestos cement pipe. The migration of tetrachloroethylene through the vinyl lining was modeled as

Avery H. Demond

1985-01-01

31

A freshwater anaerobe coupling acetate oxidation to tetrachloroethylene dehalogenation.  

PubMed Central

Strain TT4B has been isolated from anaerobic sediments known to be contaminated with a variety of organic solvents. It is a gram-negative, rod-shaped bacterium and grew anaerobically with acetate as the electron donor and tetrachloroethylene as the electron acceptor in a mineral medium. cis-Dichloroethylene was the halogenated product. This strain did not grow fermentatively and used only acetate or pyruvate as electron donors. Tetrachloroethylene and trichloroethylene were used as electron acceptors, as were ferric nitriloacetate and fumarate. Nitrogen and sulfur oxyanions were not able to substitute as the electron acceptor for this organism. Modest growth occurred in a two-phase system with 1 ml of hexadecane containing 50 to 200 mM tetrachloroethylene (aqueous concentrations, 25 to 100 microM) and 10 ml of anaerobic mineral solution with Na2S as the reducing agent. Growth was completely inhibited at tetrachloroethylene levels above 100 microM.

Krumholz, L R; Sharp, R; Fishbain, S S

1996-01-01

32

The Removal of Tri (TCE) and Tetrachloroethylene (PCE) from Aqueous Solution using High Energy Electrons  

Microsoft Academic Search

Trichloroethylene (TCE) and tetrachloroethylene (PCE) are common groundwater contaminants that persist inithe environment. An innovative treatment process employing high energy electron beam irradiation has been shown to be an effective process for treating TCE- or PCE-contaminated water, wastewater, and water containing suspended solids.Experiments conducted at the Electron Beam Research Facility, Miami, Florida, have led to a better understanding of the

William J. Cooper; David E. Meacham; Michael G. Nickelsen; Kaijun Lin; David B. Ford; Charles N. Kuruczand; Thomas D. Waite

1993-01-01

33

Tetrachloroethylene leached from lined asbestos-cement pipe into drinking water [with Discussion  

Microsoft Academic Search

Tetrachloroethylene has been detected in concentrations ranging from a few micrograms per litre to several milligrams per litre in dead ends of water distribution systems made of vinyl-toluene-lined asbestos-cement pipe. About 1600 km (1000 mi) of this lined pipe is being used, primarily in New England. Tetrachloroethylene concentrations can be lessened by flushing and installing continuous bleeders, two of the

Charles D. Larson; O. Thomas Love Jr.; Gardiner Reynolds III; S. Wyatt McCallie; R. H. Moser; Edward J. Calabrese

1983-01-01

34

Constitutive Degradation of Trichloroethylene by an Altered Bacterium in a Gas-Phase Bioreactor.  

National Technical Information Service (NTIS)

Pseudomonas cepacia G4 expresses a unique toluene orth-monooxygenase (Tom) that enables it to degrade toluene and trichloroethylene (TCE). Transposon mutants of G4 have been isolated that constitutively express Tom. Two fixed-film bioreactor designs were ...

M. S. Shields M. J. Reagin R. R. Gerger C. Somerville R. Schaubhut R. Campbell J. Hu-Primmer

1994-01-01

35

Cytotoxicity Associated with Trichloroethylene Oxidation in Burkholderia cepacia G4  

Microsoft Academic Search

The effects of trichloroethylene (TCE) oxidation on toluene 2-monooxygenase activity, general respiratory activity, and cell culturability were examined in the toluene-oxidizing bacterium Burkholderia cepacia G4. Nonspecific damage outpaced inactivation of toluene 2-monooxygenase in B. cepacia G4 cells. Cells that had degraded approximately 0.5 mmol of TCE (mg of cells 21 ) lost 95% of their acetate-dependent O2 uptake activity (a

CHRIS M. YEAGER; PETER J. BOTTOMLEY; DANIEL J. ARP

2001-01-01

36

MUTANTS OF PSEUDOMONAS CEPACIA G4 DEFECTIVE IN CATABOLISM OF AROMATIC COMPOUNDS AND TRICHLOROETHYLENE  

EPA Science Inventory

Pseudomonas cepacia strain G4 possesses a novel pathway of toluene catabolism that is shown to be responsible for the degradation of trichloroethylene (TCE). his pathway involves conversion of toluene via o-cresol to 3-methylcatechol. o determine the enzyme f toluene degradation ...

37

TRICHLOROETHYLENE IHIBITS VOLTAGE-SENSITIVE CALCIUM CURRENTS IN DIFFERENTIATED PC 12 CELLS.  

EPA Science Inventory

ABSTRACT BODY: It has been demonstrated recently that volatile organic compounds (VOCs)such as toluene, perchloroethylene and trichloroethylene inhibit function of voltage-sensitive calcium channels (VSSC). Such actions are hypothesized to contribute to the acute neurotoxicity of...

38

40 CFR 433.11 - Specialized definitions.  

Code of Federal Regulations, 2011 CFR

...Bis (2-chloroethoxy) methane Methylene chloride (dichloromethane) Methyl chloride (chloromethane) Methyl bromide (bromomethane...Tetrachloroethylene Toluene Trichloroethylene Vinyl chloride (chloroethylene) Aldrin Dieldrin...

2011-07-01

39

The photodissociation dynamics of tetrachloroethylene  

SciTech Connect

We present a direct current slice imaging study of tetrachloroethylene (C{sub 2}Cl{sub 4}) photodissociation, probing the resulting ground state Cl ({sup 2}P{sub 3/2}) and spin-orbit excited state Cl* ({sup 2}P{sub 1/2}) products. We report photofragment images, total translational energy distributions and the product branching ratio of Cl*/Cl following dissociation at 235 and 202 nm, obtained using a two-color reduced-Doppler dissociation/probe. Near 235 nm, the Cl translational energy distribution shows a peak at the limit of the available energy, indicating a direct dissociation through a {sigma}*(C-Cl) (leftarrow){pi} (C=C) transition, which is superimposed on a broader underlying distribution. The ground state Cl image and associated translational energy distribution at 202 nm is broad and peaked at lower energy, suggesting either internal conversion to the ground state or a lower excited state prior to dissociation. The Cl* images are similarly broad at both wavelengths. The branching ratio is presented as a function of recoil energy, but after integration shows a near-statistical average of Cl:Cl* as 70:30 at both wavelengths. All the images are largely isotropic, with anisotropy parameters ({beta}) of 0.05 {+-} 0.03.

Herath, Nuradhika; Hause, Michael L.; Suits, Arthur G. [Department of Chemistry, Wayne State University, Detroit, Michigan 48202 (United States)

2011-04-28

40

Trichloroethylene. I. An overview  

Microsoft Academic Search

Trichloroethylene (TCE) has been an industrial chemical of some importance for the past 50 years. First synthesized by Fischer in 1864, TCE has enjoyed considerable industrial usage as a degreaser and limited medical use as an inhalation anesthetic and analgesic.This TCE overview provides a narrative survey of the reference literature. Highlights include history, nomenclature, physical and chemical properties, manufacture, analysis,

E. M. Waters; H. B. Gerstner; J. E. Huff

1977-01-01

41

Tetrachloroethylene Emissions and Exposure in Dry Cleaning  

Microsoft Academic Search

Tetrachloroethylene (PCE) emissions and the exposure of workers in six commercial and three industrial dry-cleaning establishments that use dry-to-dry machines were determined. The personal samples and area samples [8-hr time-weighted average (TWA) and short-term exposure] were collected with charcoal tubes and passive monitors. The temporal variation of PCE concentration in the workplace air was monitored using a Fourier transform infrared

J. Räisänen; R. Niemelä; C. Rosenberg

2001-01-01

42

Trichloroethylene (TCE) adsorption using sustainable organic mulch.  

PubMed

Soluble substrates (electron donors) have been commonly injected into chlorinated solvent contaminated plume to stimulate reductive dechlorination. Recently, different types of organic mulches with economic advantages and sustainable benefits have received much attention as new supporting materials that can provide long term sources of electron donors for chlorinated solvent bioremediation in engineered biowall systems. However, sorption capacities of organic mulches for chlorinated solvents have not been studied yet. In this study, the physiochemical properties of organic mulches (pine, hardwood and cypress mulches) were measured and their adsorption capacity as a potential media was elucidated. Single, binary and quaternary isotherm tests were conducted with trichloroethylene (TCE), tetrachloroethylene (PCE), trans-dichloroethylene (trans-DCE) and cis-dichloroethylene (cis-DCE). Among the three tested mulches, pine mulch showed the highest sorption capacity for the majority of the tested chemicals in single isotherm test. In binary or quaternary isotherm tests, competition among chemicals appears to diminish the differences in Q(e) for tested mulches. However, pine mulch also showed higher adsorption capacity for most chemicals when compared to hardwood and cypress mulches in the two isotherm tests. Based upon physicochemical properties of the three mulches, higher sorption capacity of pine mulch over hardwood and cypress mulches appears to be attributed to a higher organic carbon content and the lower polarity. PMID:20605328

Wei, Zongsu; Seo, Youngwoo

2010-05-02

43

ROUTE-DEPENDENT EFFECTS OF TOLUENE ON SIGNAL DETECTION BEHAVIOR IN RATS.  

EPA Science Inventory

The acute effects of toluene and other solvents on behavior are thought to depend upon their concentration in the brain. We have shown previously that inhaled toluene and trichloroethylene disrupt sustained attention in rats as assessed with a visual signal detection task (SDT). ...

44

Co-metabolic degradation of trichloroethylene by Pseudomonas putida in a fibrous bed bioreactor  

Microsoft Academic Search

Co-metabolic degradation of trichloroethylene (TCE) by Pseudomonas putida F1 was investigated in a novel bioreactor with a fibrous bed. A pseudo-first-order rate constant for TCE degradation was 1.4 h-1 for 2.4 to 100 mg TCE l-1. Competitive inhibition of toluene on TCE removal could be prevented in this bioreactor. 90% TCE was removed over 4 h when 95 mg toluene

Gia-Luen Guo; Dyi-Hwa Tseng; Shir-Ly Huang

2001-01-01

45

Toluene embryopathy  

SciTech Connect

Three children with microcephaly, central nervous system dysfunction, minor craniofacial and limb anomalies, and variable growth deficiency were born to women who inhaled large quantities of pure toluene throughout pregnancy. The features in there patients were reminiscent of the patterns of malformation previously described following in utero exposure to alcohol, certain anticonvulsants, and hyperphenylalaninemia. It is possible that there is a variable and nonspecific teratogenic phenotype characterized by alterations in growth, development, and morphogenesis. Careful evaluation and monitoring of infants exposed to toluene in utero are needed to determine the significance of these findings.

Hersh, J.H.; Podruch, P.E.; Rogers, G.; Weisskopf, B.

1985-06-01

46

Selection of a 'Pseudomonas cepacia' Strain Constitutive for the Degradation of Trichloroethylene.  

National Technical Information Service (NTIS)

Tn5 insertion mutants of Pseudomonas cepacia G4 that were unable to degrade trichloroethylene (TCE), toluene, or phenol or to transform m-trifluoromethyl phenol (TFMP) to 7,7,7-trifluoro-2-hydroxy-6-oxo-2,4-heptadienoic acid (TFHA) were produced. Spontane...

M. S. Shields M. J. Reagin

1992-01-01

47

UNCERTAINTIES IN TRICHLOROETHYLENE PHARMACOKINETIC MODELS  

EPA Science Inventory

Understanding the pharmacokinetics of a chemical¯its absorption, distribution, metabolism, and excretion in humans and laboratory animals ¯ is critical to the assessment of its human health risks. For trichloroethylene (TCE), numerous physiologically-based pharmacokinetic (PBPK)...

48

Atmospheric oxidation of tetrachloroethylene: an ab initio study.  

PubMed

A number of experimental studies have been conducted to determine the atmospheric oxidation of tetrachloroethylene, many indicating phosgene as the major product. Although various mechanisms have been suggested, the mechanism of phosgene production is unclear. Additionally, confusion has arisen over the role chlorine atoms may play in the oxidation of tetrachloroethylene and the products produced. To clarify these points, this study presents a comprehensive computational study of both the hydroxyl radical and the chlorine atom initiated atmospheric oxidation mechanism of tetrachloroethylene. The energetics for the oxidation of tetrachloroethylene (C(2)Cl(4)) are computed using ab initio methods. Potential energy surfaces of the reaction pathways are determined from the computations. This study clarifies the involvement of the Cl-initiated reaction pathways in the oxidation of tetrachloroethylene. Results from this work suggest that the final products are primarily from the Cl-initiated oxidation and include: trichloroacetyl chloride [ClC(O)CCl(3)], phosgene [C(O)Cl(2)], and regeneration of the initiating chlorine atom. PMID:20669984

Christiansen, Carrie J; Francisco, Joseph S

2010-09-01

49

Transformation capacities of chlorinated organics by mixed cultures enriched on methane, propane, toluene, or phenol  

Microsoft Academic Search

The degradation of trichloroethylene (TCE), chloroform (CF), and 1,2-dichloroethane (1,2-DCA) by four aerobic mixed cultures (methane, propane, toluene, and phenol oxidizers) growth under similar chemostat conditions was measured. Methane and propane oxidizers were capable of degrading both saturated and unsaturated chlorinated organics (TCE, CF, and 1,2-DCA). Toluene and phenol oxidizers degraded TCE but were not able to degrade CF, 1,2-DCA,

Hsiao-Lung Chang; Lisa Alvarez-Cohen

1995-01-01

50

Constitutive degradation of trichloroethylene by an altered bacterium in a gas-phase bioreactor. Book chapter  

SciTech Connect

Pseudomonas cepacia G4 expresses a unique toluene orth-monooxygenase (Tom) that enables it to degrade toluene and trichloroethylene (TCE). Transposon mutants of G4 have been isolated that constitutively express Tom. Two fixed-film bioreactor designs were investigated for the exploitation of one such constitutive strain (G4 PR1) in the degradation of vapor-phase TCE. DNA probe analysis indicates that the genes responsible for the toluene catabolic pathway are located on a large plasmid of G4 (> or = 150 kb) termed pG4L. The authors propose that pG4L will serve as a archetype for a new class of catabolic plasmid known as Tom, which encodes an ortho-hydroxylation pathway for the degradation of benzene, toluene, o-xylene, cresols, and phenol.

Shields, M.S.; Reagin, M.J.; Gerger, R.R.; Somerville, C.; Schaubhut, R.

1994-01-01

51

Cometabolic Degradation of Trichloroethylene by Single and Two-Phase Systems  

Microsoft Academic Search

The cometabolic degradation of trichloroethylene (TCE) by Pseudomonas putida F1 (strain ATCC 700007) at different concentrations was studied in single- and two-phase systems using 2-undecanone as the second organic phase. Toluene vapors were used as the primary growth substrate for Pseudomonas putida F1. The effects of the biomass concentration and the phase ratio on the biodegradation process were investigated. The

Tareq Abu Hamed; Emine Bayraktar; Tanju Mehmetoglu; Ülkü Mehmetoglu

2012-01-01

52

Removal of gaseous trichloroethylene (TCE) in a composite membrane biofilm reactor  

Microsoft Academic Search

A membrane biofilm reactor (MBfR) was investigated for the degradation of trichloroethylene (TCE) vapors inoculated by Burkholderia vietnamiensis G4. Toluene (TOL) was used as the primary substrate. The MBfR was loaded sequentially with TOL, TCE (or both) during 110 days. In this study, a maximum steady-state TCE removal efficiency of 23% and a maximum volumetric elimination capacity (EC) of 2.1

Amit Kumar; Aline Vercruyssen; Jo Dewulf; Piet Lens; Herman Van Langenhove

2012-01-01

53

Mutants of Pseudomonas cepacia G4 defective in catabolism of aromatic compounds and trichloroethylene.  

PubMed Central

Pseudomonas cepacia G4 possesses a novel pathway of toluene catabolism that is shown to be responsible for the degradation of trichloroethylene (TCE). This pathway involves conversion of toluene via o-cresol to 3-methylcatechol. In order to determine the enzyme of toluene degradation that is responsible for TCE degradation, chemically induced mutants, blocked in the toluene ortho-monooxygenase (TOM) pathway of G4, were examined. Mutants of the phenotypic class designated TOM A- were all defective in their ability to oxidize toluene, o-cresol, m-cresol, and phenol, suggesting that a single enzyme is responsible for conversion of these compounds to their hydroxylated products (3-methylcatechol from toluene, o-cresol, and m-cresol and catechol from phenol) in the wild type. Mutants of this class did not degrade TCE. Two other mutant classes which were blocked in toluene catabolism, TOM B-, which lacked catechol-2,3-dioxygenase, and TOM C-, which lacked 2-hydroxy-6-oxoheptadienoic acid hydrolase activity, were fully capable of TCE degradation. Therefore, TCE degradation is directly associated with the monooxygenation capability responsible for toluene, cresol, and phenol hydroxylation.

Shields, M S; Montgomery, S O; Cuskey, S M; Chapman, P J; Pritchard, P H

1991-01-01

54

SURFACTANT ENHANCED REMEDIATION OF SOIL COLUMNS CONTAMINATED BY RESIDUAL TETRACHLOROETHYLENE  

EPA Science Inventory

The ability of aqueous surfactant solutions to recover tetrachloroethylene (PCE) entrapped in Ottawa and was evaluated in four column experiments. esidual PCE was emplaced by injecting 14 C-labeled PCE into water-saturated soil columns and displacing the free product with water. ...

55

The effect of sulfide on the reductive dehalogenation of tetrachloroethylene  

Microsoft Academic Search

One of the potential variables that appears to play a major role in the development and dehalogenation ability of bacterial cultures is the external reductant employed in the research to reduce the liquid anaerobic medium. In this research, the effect of the addition of the external reductant, sodium sulfide, on the reductive dehalogenation of tetrachloroethylene was examined. Variations in dehalogenation,

Robert Watson Holden

1999-01-01

56

40 CFR 469.12 - Specialized definitions.  

Code of Federal Regulations, 2011 CFR

...Dichlorobenzene 1,4, Dichlorobenzene ethylbenzene 1,1,1 Trichloroethane methylene chloride naphthalene 2 Nitrophenol phenol bis (2-ethylhexyl) phthalate tetrachloroethylene toluene trichloroethylene 2 Chlorophenol 2,4 Dichlorophenol...

2011-07-01

57

UPDATED CARCINOGENICITY ASSESSMENT FOR TETRACHLOROETHYLENE (PERCHLOROETHYLENE, PERC, PCE): ADDENDUM TO THE HEALTH ASSESSMENT DOCUMENT FOR TETRACHLOROETHYLENE (PERCHLOROETHYLENE). EXTERNAL REVIEW DRAFT  

EPA Science Inventory

The Office of Health and Environmental Assessment has prepared the addendum to serve as a source document for EPA use. The addendum updates EPA's July 1985 Health Assessment Document for Tetrachloroethylene (Perchloroethylene, PERC, PCE) by providing a review of the findings of t...

58

Mutants of Pseudomonas cepacia G4 defective in catabolism of aromatic compounds and trichloroethylene  

SciTech Connect

Pseudomonas cepacia G4 possesses a novel pathway of toluene catabolism that is shown to be responsible for the degradation of trichloroethylene (TCE). This pathway involves conversion of toluene via o-cresol to 3-methylcatechol. In order to determine the enzyme of toluene degradation that is responsible for TCE degradation, chemically induced mutants, blocked in the toluene ortho-monooxygenase (TOM) pathway of G4, were examined. Mutants of the phenotypic class designated TOM A{sup {minus}} were all defective in their ability to oxidize toluene, o-cresol, m-cresol, and phenol, suggesting that a single enzyme is responsible for conversion of these compounds to their hydroxylated products (3-methylcatechol from toluene, o-cresol, and m-cresol and catechol from phenol) in the wild type. Mutants of this class did not degrade TCE. Two other mutant classes which lacked 2-hydroxy-6-oxoheptadienoic acid hydrolase activity, were fully capable of TCE degradation. Therefore, TCE degradation is directly associated with the monooxygenation capability responsible for toluene, cresol, and phenol hydroxylation.

Sheilds, M.S.; Montgomery, S.O. (Technical Resources Inc., Gulf Breeze, FL (USA)); Cuskey, S.M.; Chapman, P.J.; Pritchard, P.H. (Environmental Protection Agency, Gulf Breeze, FL (USA))

1991-07-01

59

Lactate Injection by Electric Currents for Bioremediation of Tetrachloroethylene in Clay.  

PubMed

Biological transformation of tetrachloroethylene (PCE) in silty clay samples by ionic injection of lactate under electric fields is evaluated. To prepare contaminated samples, a silty clay slurry was mixed with PCE, inoculated with KB-1(®) dechlorinators and was consolidated in a 40 cm long cell. A current density between 5.3 and 13.3 A m(-2) was applied across treated soil samples while circulating electrolytes containing 10 mg L(-1) lactate concentration between the anode and cathode compartments to maintain neutral pH and chemically reducing boundary conditions. The total adsorbed and aqueous PCE was degraded in the soil to trichloroethylene (TCE), cis-1,2-dichloroethene (cis-DCE), vinyl chloride (VC) and ethene in 120 d, which is about double the time expected for transformation. Lactate was delivered into the soil by a reactive transport rate of 3.7 cm(2) d(-1) V(-1). PCE degradation in the clay samples followed zero order transformation rates ranging from 1.5 to 5 mg L(-1) d(-1) without any significant formation of TCE. cis-DCE transformation followed first order transformation rates of 0.06 to 0.10 per day. A control experiment conducted with KB-1 and lactate, but without electricity did not show any significant lactate buildup or cis-DCE transformation because the soil was practically impermeable (hydraulic conductivity of 2×10(-7) cm s(-1)). It is concluded that ionic migration will deliver organic additives and induce biological activity and complete PCE transformation in clay, even though the transformation occurs under slower rates compared to ideal conditions. PMID:23264697

Wu, Xingzhi; Gent, David B; Davis, Jeffrey L; Alshawabkeh, Akram N

2012-06-22

60

Reductive dechlorination of tetrachloroethylene and trichloroethylene by mackinawite (FeS) in the presence of metals: reaction rates.  

PubMed

Reductive dechlorination by mackinawite (FeS) is an important transformation pathway for chloroethylenes in anoxic environments. Yet, the impact of metals on reductive dechlorination is not well understood, despite their frequent cooccurrence with chloroethylenes. Fe(II), Co(II), Ni(II), and Hg(II) were evaluated for their impact on the dechlorination rates of PCE and TCE by FeS. Compared with unamended FeS batches, the dechlorination rates of both chloroethylenes decreased by addition of 0.01 M Fe(II). Relative to 0.01 M Fe(II)-added FeS batches, the dechlorination rates increased in FeS batches amended with 0.01 M of Co(II) and Hg(II), whereas the rates decreased in 0.01 M Ni(II)-added batches. While significantly impacting the dechlorination rates, the amended metals were quantitatively sequestered by FeS mainly because of formation of metal sulfides. Comparison of the dechlorination rates between metal-added FeS batches and metal sulfide batches suggests that discrete metal sulfides do not form in metal-added FeS batches. The observed exceptionally high reactivity of CoS suggests that it may be useful in reactive permeable barrier applications because of its stability in anoxic waters. The dechlorination rates of PCE and TCE significantly varied with Fe(ll) amendment concentrations (Fe(II)0), indicating the presence of different types of solid-bound Fe phases with Fe(II)o. PMID:17948784

Jeong, Hoon Y; Hayes, Kim F

2007-09-15

61

DECHLORINATION OF TRICHLOROETHYLENE USING ELECTROCHEMICAL METHODS  

EPA Science Inventory

Electrochemical degradation (ECD) is used to decontaminate organic and inorganic contaminants through oxidative or reductive processes. The ECD of Trichloroethylene (TCE) dechlorinates TCE through electric reduction. TCE dechlorination presented in the literature utilized electro...

62

Biodegradation of Trichloroethylene and Biomanipulation of Aquifers.  

National Technical Information Service (NTIS)

Three distinct aspects of the biodegradation process in a porous media were addressed. The effect of the trichloroethylene(TCE) concentration on bacterial activity was investigated. The results showed that the dissolved phase concentration directly affect...

P. R. Jaffe S. W. Taylor N. H. Baek P. Christopher D. Milly

1988-01-01

63

NIOSH (National Institute for Occupational Safety and Health) Criteria for a Recommended Standard: Occupational Exposure to Tetrachloroethylene (Perchloroethylene).  

National Technical Information Service (NTIS)

The report provides relevant data concerning the exposure of humans to tetrachloroethylene within the workplace. Recommendations for a tetrachloroethylene standard are provided based on analysis of data. The document covers the workplace environment, medi...

1976-01-01

64

Systematic Literature Review of Uses and Levels of Occupational Exposure to Tetrachloroethylene  

Microsoft Academic Search

Tetrachloroethylene has been one of the most widely used chlorinated solvents in the United States. This review provides a basis for tetrachloroethylene exposure assessment in population-based case-control studies. We performed literature searches in MEDLINE, TOXLINE, NIOSHTIC, and the NIOSH Health Hazard Evaluation databases using relevant search terms. We calculated weighted arithmetic means from the measurement data and compiled these into

Laura S. Gold; Anneclaire J. De Roos; Martha Waters; Patricia Stewart

2008-01-01

65

Effect of sorption and desorption resistance on aerobic trichloroethylene biodegradation in soils.  

PubMed

Biodegradation of trichloroethylene (TCE) by toluene-degrading bacteria was measured under aerobic conditions in aqueous and soil-slurry batch microcosms. For soil-phase experiments, a freshly contaminated soil and a soil containing only the desorption-resistant fraction of TCE were tested. In both cases, presence of soil resulted in biodegradation rates substantially lower than those determined in the absence of soil. In aqueous-phase experiments, an appreciable increase in the rate and extent of TCE biodegradation was observed in microcosms when toluene was added multiple times. The TCE degradation rates were clearly correlated with toluene dioxygenase (TOD) enzyme activity over time, thus providing an indication of the cometabolic pathway employed by the microbial population. In soil-slurry experiments containing freshly contaminated soil, a TCE degradation rate of approximately 150 microg TCE/kg/h was observed during the first 39-h period, and then the TCE degradation rate slowed considerably to 0.59 and 0.84 microg TCE/kg/h for microcosms receiving one and two additions of toluene, respectively. The TCE degradation rates in soil-slurry microcosms containing the desorption-resistant fraction of TCE-contaminated soil were approximately 0.27 and 0.32 microg TCE/kg/h in microcosms receiving one and two additions of toluene, respectively. It is clear from these results that mass transfer into the aqueous phase limited bioavailability of TCE in the contaminated soil. PMID:12152760

Lee, Sangjin; Moe, William M; Valsaraj, Kalliat T; Pardue, John H

2002-08-01

66

Trichloroethylene and cancer: a carcinogen on trial.  

PubMed

The organic solvent trichloroethylene has been used in dry cleaning, as an industrial degreasing agent and as a solvent for oils and resins; large numbers of workers have been exposed to trichloroethylene, mainly by inhalation. Trichloroethylene has been categorised as a Group 2A carcinogen (probably carcinogenic to humans) by the International Agency for Research on Cancer (World Health Organization) and a Category 2 carcinogen (to be regarded as carcinogenic to humans) by the Australian National Industrial Chemicals Notification and Assessment Scheme. The Administrative Appeals Tribunal was asked to determine the validity of classifying trichloroethylene as a Category 2 rather than a Category 3 (data inadequate for making a satisfactory assessment) carcinogen. In the AAT's determination, relevant epidemiological evidence was not taken into account because such evidence concerned tumour sites apart from the kidney (the site of tumour induction by trichloroethylene in rats). This mode of evaluation is fundamentally different from that used by the International Agency for Research on Cancer. The precedent set by the consideration of carcinogenicity data in this case could have significant implications for classification of other putative carcinogens PMID:11280697

Stewart, B W

2001-03-01

67

Early Lifestage Exposure and Potential Developmental Susceptibility to Tetrachloroethylene [Journal Article  

EPA Science Inventory

Tetrachloroethylene, also known as perchloroethylene or "perc", is a highly volatile and lipophilic solvent widely used in dry cleaning, textile processing, and metal-cleaning operations. The limited epidemiological and toxicological data available for developmental lifestage ex...

68

Benzene and toluene biodegradation down gradient of a zero-valent iron permeable reactive barrier.  

PubMed

This study simulated benzene and toluene biodegradation down gradient of a zero-valent iron permeable reactive barrier (ZVI PRB) that reduces trichloroethylene (TCE). The effects of elevated pH (10.5) and the presence of a common TCE dechlorination by product [cis-1,2-dichloroethene (cis-1,2-DCE)] on benzene and toluene biodegradation were evaluated in batch experiments. The data suggest that alkaline pH (pH 10.5), often observed down gradient of ZVI PRBs, inhibits Fe(III)-mediated biotransformation of both benzene and toluene. Removal was reduced by 43% for benzene and 26% for toluene as compared to the controls. The effect of the addition of cis-1,2-DCE on benzene and toluene biodegradation was positive and resulted in removal that was greater than or equal to the controls. These results suggest that, at least for cis-1,2-DCE, its formation may not be toxic to iron-reducing benzene and toluene degrading bacteria; however, for microbial benzene and toluene removal down gradient of a ZVI PRB, it may be necessary to provide pH control, especially in the case of a biological PRB that is downstream from a ZVI PRB. PMID:21316847

Chen, Liang; Liu, Fei; Liu, Yulong; Dong, Hongzhong; Colberg, Patricia J S

2011-01-26

69

Silylene- and disilyleneacetylene polymers from trichloroethylene  

DOEpatents

Organosilane polymers having recurring silyleneacetylene and/or disilyleneacetylene units are prepared in a one-pot synthesis from trichloroethylene. Depending on the organic substituents (R and R'), these polymers have useful film-forming properties, and are converted to the ceramic, silicon carbide upon heating in very uniform high yields. They can also be pulled into fibers.

Barton, Thomas J. (Ames, IA); Ijadi-Maghsoodi, Sina (Ames, IA)

1990-07-10

70

Silylene- and disilyleneacetylene polymers from trichloroethylene  

DOEpatents

Organosilane polymers having recurring silyleneacetylene and/or disilyleneacetylene units are prepared in a one-pot synthesis from trichloroethylene. Depending on the organic substituents (R and R[prime]), these polymers have useful film-forming properties, and are converted to the ceramic, silicon carbide upon heating in very uniform high yields. They can also be pulled into fibers.

Barton, T.J.; Ijadi-Maghsoodi, S.

1990-07-10

71

Toxicology of Toluene Diisocyanate  

Microsoft Academic Search

In studies on animals, toluene diisocyanate (TDI) was a contact and respiratory sensitizer, was not toxic by the oral or dermal routes, but was irritating, and toxic by inhalation. The respiratory tract was the target in acute, subchronic, and chronic exposure studies. Typically, at concentrations of above 0.1 ppm (parts per million), clinical signs of nasal irritation were evident, and

Michael A. Collins

2002-01-01

72

Photoinduced decomposition of trichloroethylene in soil components  

SciTech Connect

The photoinduced decomposition of trichloroethylene adsorbed on Ca-montmorillonite by long-wavelength UV irradiation has been studied in a quartz tube open to air or through which air or oxygen is passed. Solid-sample and liquid-solution NMR techniques were used to identify apparent products or intermediates of the photodecomposition. Dichloroacetic acid was identified as a major organic product/intermediate; substantial amounts of pentachloroethane and trichloroacetic acid were also identified. The formation of CO{sub 2} was characterized quantitatively by wet chemical analysis. About 40% and 57%, respectively, of the total carbon of trichloroethylene was converted to carbon dioxide in air and O{sub 2} environments over a period of 16 days. Phosgene and HCl were also detected. The photodecomposition of trichloroethylene adsorbed on whole soil, on Zn{sup 2+}-exchanged and Cu{sup 2+}-exchanged montmorillonites, on kaolinite, and on silica gel was also examined in less detail; qualitatively, the conversion of trichloroethylene to dichloroacetic acid in a 48-h period occurred with the following order of decreasing efficiencies: Zn{sup 2+}-montmorillonite > silica gel > kaolinite > Ca{sup 2+}-montmorillonite > whole soil > Cu{sup 2+}-montmorillonite. These results show that the photoinduced decomposition of adsorbed trichloroethylene occurs on a variety of adsorbents, generating products and intermediates that are similar to what have been reported previously for TiO{sub 2}-based photodecomposition but with much longer time scales. These conversions can, therefore, be expected to occur in sunlight at the air-soil interface.

Tao, T.; Yang, J.J.; Maciel, G.E. [Colorado State Univ., Fort Collins, CO (United States). Dept. of Chemistry

1999-01-01

73

Linking indoor air and pharmacokinetic models to assess tetrachloroethylene risk  

SciTech Connect

Physiologically based pharmacokinetic (PBPK) models describing the uptake, metabolism, and excretion of xenobiotic compounds are now proposed for use in regulatory health-risk assessments. In this study the authors investigate the extent of PCE metabolism arising from domestic respiratory exposure to tetrachloroethylene (PCE) from ground water, as predicted using a PBPK model. Indoor exposure patterns they use as input to the PBPK model are realistic ones generated from a three-compartment model describing volatilization of PCE from domestic water into household air. Values they use for the metabolic parameters of the PBPK model are estimated from data on urinary metabolites in workers exposed to PCE. It is shown that for respiratory PCE exposure due to typical levels of PCE in ground water, use of time-weighted average air concentrations with a steady-state PBPK model yields estimates of total metabolized PCE similar to those obtained using completely dynamic modeling, despite considerable uncertainty in key exposure- and metabolic-model parameters. These findings suggest that, for PCE, risk estimation taking pharmacokinetics into account may be accomplished using a simple analytic approach.

Bogen, K.T.; McKone, T.E.

1988-12-01

74

Indoor tetrachloroethylene levels and determinants in Paris dwellings.  

PubMed

There is growing public health concern about indoor air quality. Tetrachloroethylene (PERC), a chlorinated volatile organic compound widely used as a solvent in dry cleaning facilities, can be a residential indoor air pollutant. As part of an environmental investigation included in the PARIS (Pollution and asthma Risk: an Infant Study) birth cohort, this study firstly aimed to document domestic PERC levels, and then to identify the factors influencing these levels using standardized questionnaires about housing characteristics and living conditions. Air samples were collected in the child's bedroom over one week using passive devices when infants were 1, 6, 9, and 12 months. PERC was identified and quantified by gas chromatography/mass spectrometry. PERC annual domestic level was calculated by averaging seasonal levels. PERC was omnipresent indoors, annual levels ranged from 0.6 to 124.2 ?g/m3. Multivariate linear and logistic regression models showed that proximity to dry cleaning facilities, do-it-yourself activities (e.g.: photographic development, silverware), presence of air vents, and building construction date (<1945) were responsible for higher domestic levels of PERC. This study, conducted in an urban context, provides helpful information on PERC contamination in dwellings, and identifies parameters influencing this contamination. PMID:23127492

Roda, Célina; Kousignian, Isabelle; Ramond, Anna; Momas, Isabelle

2012-11-03

75

Development and Characterization of a Green Fluorescent Protein-Based Bacterial Biosensor for Bioavailable Toluene and Related Compounds†  

PubMed Central

A green fluorescent protein-based Pseudomonas fluorescens strain A506 biosensor was constructed and characterized for its potential to measure benzene, toluene, ethylbenzene, and related compounds in aqueous solutions. The biosensor is based on a plasmid carrying the toluene-benzene utilization (tbu) pathway transcriptional activator TbuT from Ralstonia pickettii PKO1 and a transcriptional fusion of its promoter PtbuA1 with a promoterless gfp gene on a broad-host-range promoter probe vector. TbuT was not limiting, since it was constitutively expressed by being fused to the neomycin phosphotransferase (nptII) promoter. The biosensor cells were readily induced, and fluorescence emission after induction periods of 3 h correlated well with toluene, benzene, ethylbenzene, and trichloroethylene concentrations. Our experiments using flow cytometry show that intermediate levels of gfp expression in response to toluene reflect uniform induction of cells. As the toluene concentration increases, the level of gfp expression per cell increases until saturation kinetics of the TbuT-PtbuA1 system are observed. Each inducer had a unique minimum concentration that was necessary for induction, with Kapp values that ranged from 3.3 ± 1.8 ?M for toluene to 35.6 ± 16.6 ?M for trichloroethylene (means ± standard errors of the means), and maximal fluorescence response. The fluorescence response was specific for alkyl-substituted benzene derivatives and branched alkenes (di- and trichloroethylene, 2-methyl-2-butene). The biosensor responded in an additive fashion to the presence of multiple inducers and was unaffected by the presence of compounds that were not inducers, such as those present in gasoline. Flow cytometry revealed that, in response to toxic concentrations of gasoline, there was a small uninduced population and another larger fully induced population whose levels of fluorescence corresponded to the amount of effectors present in the sample. These results demonstrate the potential for green fluorescent protein-based bacterial biosensors to measure environmental contaminants.

Stiner, Lawrence; Halverson, Larry J.

2002-01-01

76

Saturation Mutagenesis of Toluene ortho-Monooxygenase of Burkholderia cepacia G4 for Enhanced 1Naphthol Synthesis and Chloroform Degradation  

Microsoft Academic Search

Directed evolution of toluene ortho-monooxygenase (TOM) of Burkholderia cepacia G4 previously created the hydroxylase -subunit (TomA3) V106A variant (TOM-Green) with increased activity for both trichloroethylene degradation (twofold enhancement) and naphthalene oxidation (six-times-higher activity). In the present study, saturation mutagenesis was performed at position A106 with Escherichia coli TG1\\/pBS(Kan)TOMV106A to improve TOM activity for both chloroform degradation and naphthalene oxidation. Whole

Lingyun Rui; Young Man Kwon; Ayelet Fishman; Kenneth F. Reardon; Thomas K. Wood

2004-01-01

77

Photocatalytic oxidation of trichloroethylene in humidified atmosphere  

Microsoft Academic Search

Gas-phase UV-assisted catalytic oxidation of trichloroethylene (TCE) has been studied over TiO2 glass fiber cloth (TiO2-GFC) in a cylindrical batch reactor at different humidity levels. The apparent intermediates and products were determined by Fourier transform infrared (FTIR) spectroscopy. The effect of humidity on the photochemical oxidation reaction of TCE has also been studied in order to further elucidate the inhibitive

Placidus B. Amama; Kiminori Itoh; Masayuki Murabayashi

2001-01-01

78

Toluene biofiltration enhanced by ryegrass.  

PubMed

Toluene biofiltration by microorganisms (an unplanted treatment) and by the combination of ryegrass (Lolium perenne L.) and microorganisms (a planted treatment) was investigated in this study. The results showed that toluene was completely removed by the unplanted and the planted biofilters in less than 0.2 g m?³ inlet toluene concentration. Toluene removal capacity for the planted biofilter was significantly higher than that for the unplanted biofilter in the range of 0.2-0.5 g m?³ inlet toluene concentration. This study revealed a significant (p < 0.01) increase in the microbial activity in the planted biofilter in comparison with the unplanted biofilter, indicating that ryegrass growing in a biofilter would significantly (p < 0.05) enhance toluene biodegradation. PMID:23455043

Xu, Zhongjun; Wu, Meng; He, Yanyun

2013-03-03

79

Pulmonary reactions caused by welding-induced decomposed trichloroethylene  

SciTech Connect

This is the report of a welder who performed argon-shielded electric arc welding in an atmosphere containing trichloroethylene. He developed immediate respiratory symptoms, pulmonary edema 12 hours after exposure, and recurring dyspnea ten days after exposure. These pulmonary reactions might be explained by inhalation of decomposition products of trichloroethylene such as dichloroacetyl chloride and phosgene.

Sjoegren, B.P.; Plato, N.; Alexandersson, R.; Eklund, A.; Falkenberg, C. (Karolinska Hospital, Stockholm (Sweden))

1991-01-01

80

Cosolvent effects of alcohols on the Henry's law constant and aqueous solubility of tetrachloroethylene (PCE)  

Microsoft Academic Search

The effects of selected cosolvents ethyl alcohol (EtOH), isopropyl alcohol (IPA), and tertbutyl alcohol (TBA) on the Henry's law constant (H) of tetrachloroethylene (PCE) in aqueous solutions were investigated using the static headspace method. Alcohols in solution at a concentration around 20% and above acted as cosolvents increasing the aqueous solubility of PCE, which resulted in lower H values for

Tarek I Ladaa; Cindy M Lee; John T Coates; Ronald W Falta

2001-01-01

81

Continuous Determination of High-Vapor Phase Concentrations of Tetrachloroethylene Using On-Line Mass Spectrometry  

EPA Science Inventory

A method was developed to determine the vapor concentration of tetrachloroethylene (PCE) at and below its equilibrium vapor phase concentration, 168,000 μg/L (25°C). Vapor samples were drawn by vacuum into a six-port sampling valve and injected through a jet separator into an io...

82

SUBCHRONIC TOXICITY OF TETRACHLOROETHYLENE (PERCHLOROETHYLENE) ADMINISTERED IN THE DRINKING WATER OF RATS  

EPA Science Inventory

The study provides data on the effects of tetrachloroethylene in drinking solutions. The acute oral LD(50) was determined in male and female Charles River rats and found to be 3835 mg/kg for males and 3005 mg/kg for females. Male and female rats received theoretical daily doses o...

83

Euro Chlor Risk Assessment for the Marine Environment Osparcom Region: North Sea - Tetrachloroethylene  

Microsoft Academic Search

This risk assessment on tetrachloroethylene (PER) was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488\\/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs

Christ De Rooij; Jean Charles Boutonnet; Veronique Garny; Andre Lecloux; Roger Papp; Roy S Thompson; Dolf Van Wijk

1998-01-01

84

Spontaneous abortions and congenital malformations among women exposed to tetrachloroethylene in dry cleaning  

Microsoft Academic Search

STUDY OBJECTIVE: The aim of the study was to determine whether exposure to tetrachloroethylene during the first trimester of pregnancy has harmful effects on pregnancy outcome. DESIGN: The study used record linkage identification of cases and case-control comparison. SETTING: The study involved dry cleaner and laundry workers throughout Finland who had become pregnant during the study period. Controls were age

P. Kyyroenen; H. Taskinen; M. L. Lindbohm; K Hemminki; O P Heinonen

1989-01-01

85

Selection of a pseudomonas cepacia strain constitutive for the degradation of trichloroethylene  

SciTech Connect

Tn5 insertion mutants of Pseudomonas cepacia G4 that were unable to degrade trichloroethylene (TCE), toluene, or phenol or to transform m-trifluoromethyl phenol (TFMP) to 7,7,7-trifluoro-2-hydroxy-6-oxo-2,4-heptadienoic acid (TFHA) were produced. Spontaneous reversion to growth on phenol or toluene as the sole source of carbon was observed in one mutant strain, G4 5223, at a frequency of about .0004 per generation. One such revertant, G4 5223-PR1, metabolized TFMP to TFHA and degraded TCE. Unlike wild-type G4, G4 5223-PR1 constitutively metabolized both TFMP and TCE without aromatic induction. G4 5223-PR1 also degraded cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, and 1,1-dichloroethylene and oxidized naphthalene to alpha naphthol constitutively. G4 5223-PR1 exhibited a slight retardation in growth rate at TCE concentrations of greater than or equal to 530 microM, whereas G4 (which was unable to metabolize TCE under the same noninducing growth conditions) remained unaffected. The constitutive degradative phenotype of G4 5223-PR1 was completely stable through 100 generations of nonselective growth. (Copyright (c) 1992, American Society for Microbiology.)

Shields, M.S.; Reagin, M.J.

1992-01-01

86

Mineralization of Trichloroethylene by Heterotrophic Enrichment Cultures  

PubMed Central

Microbial consortia capable of aerobically degrading more than 99% of exogenous trichloroethylene (TCE) (50 mg/liter) were collected from TCE-contaminated subsurface sediments and grown in enrichment cultures. TCE at concentrations greater than 300 mg/liter was not degraded, nor was TCE used by the consortia as a sole energy source. Energy sources which permitted growth included tryptone-yeast extract, methanol, methane, and propane. The optimum temperature range for growth and subsequent TCE consumption was 22 to 37°C, and the pH optimum was 7.0 to 8.1. Utilization of TCE occurred only after apparent microbial growth had ceased. The major end products recovered were hydrochloric acid and carbon dioxide. Minor products included dichloroethylene, vinylidine chloride, and, possibly, chloroform.

Fliermans, C. B.; Phelps, T. J.; Ringelberg, D.; Mikell, A. T.; White, D. C.

1988-01-01

87

Effect of Trichloroethylene on Male Sexual Behavior: Possible Opioid Role.  

National Technical Information Service (NTIS)

Trichloroethylene (TCE) is a chlorinated hydrocarbon solvent which is widely used as an industrial degreasing agent. Workers exposed to TCE often exhibit symptoms similar to those symptoms produced by narcotics. The present studies evaluated the effects o...

J. L. Nelson H. Zenick

1986-01-01

88

Atmospheric oxidation of trichloroethylene: an ab initio study.  

PubMed

The atmospheric oxidation of trichloroethylene has previously been studied experimentally. Phosgene is thought to be the dominant product, although the mechanism of production is not well understood. Additionally, studies omitting a chlorine scavenger show the production of dichloroacetyl chloride. This influence of the chlorine atom on the trichloroethylene oxidation is not well understood. Using ab initio methods, this study presents a comprehensive computational study of both the hydroxyl radical and chlorine atom initiated atmospheric oxidation mechanisms of trichloroethylene (C(2)HCl(3)). Potential energy surfaces, including activation energies and enthalpies, are determined. The results from this study, in connection with experimental work, confirm the influence of the Cl-initiated oxidation in determining the product profile of the trichloroethylene oxidation. These products include dichloroacetyl chloride [Cl(2)CHC(O)Cl], formyl chloride [CH(O)Cl], phosgene [C(O)Cl(2)], and regeneration of the chlorine atom. PMID:20687539

Christiansen, Carrie J; Francisco, Joseph S

2010-09-01

89

National Exposure Registry Trichloroethylene (TCE) Subregistry Baseline through Followup 3.  

National Technical Information Service (NTIS)

This report provides an overview of the ATSDR Trichloroethylene (TCE) Subregistry population for Baseline through Followup 3 activities, and the results of the comparison of reporting rates of health outcomes with national norms. The TCE Subregistry inclu...

1999-01-01

90

MODEL DEVELOPMENT AND EVALUATION FOR TRICHLOROETHYLENE METABOLISM IN HUMANS  

EPA Science Inventory

Trichloroethylene (TCE) is an industrial chemical and an environmental contaminant. TCE and its metabolites may be carcinogenic and affect human health. Physiologically based pharmacokinetic (PBPK) models that differ in compartmentalization are developed for TCE metabolism, and...

91

Toxicological profile for toluene. Update. Final report  

SciTech Connect

This Statement was prepared to give you information about toluene and to emphasize the human health effects that may result from exposure to it. Toluene has been found in at least 851 of the sites on the NPL. However, the number of NPL sites evaluated for toluene is not known. This information is important because exposure to toluene may cause harmful health effects and because these sites are potential or actual sources of human exposure to toluene.

Dorsey, A.S.; Donohue, J.M.

1994-05-01

92

Study of restacked single molecular layer molybdenum disulfide with organic tetrachloroethylene included  

Microsoft Academic Search

The structure of restacked monomolecular layers of MoS2 with organic tetrachloroethylene (TCE) included was studied using X-ray powder diffraction and X-ray diffraction of thin films in reflection and transmission. It was found that the MoS2 host layers are turbostratically stacked, separated by a monolayer of TCE and that the MoS2 is strongly distorted, with the Mo in an octahedral coordination.

X. Zhou; D. Yang; R. F. Frindt

1996-01-01

93

Effects of Tetrachloroethylene on the Viability and Development of Embryos of the Japanese Medaka, Oryzias latipes  

Microsoft Academic Search

We evaluated the acute toxicity of Tetrachloroethylene (C2Cl4), and investigated its sub-chronic effects on the embryonic development of Japanese medaka (Oryzias latipes). One-day-old eggs\\/embryos of this fish species were exposed, under static renewal conditions, to serial concentrations (0,\\u000a 20, 40, 60, and 80 mg\\/L) of C2Cl4 for 96 h (acute) and 10 days (sub-chronic) time periods. The toxic endpoints evaluated

H. B. Spencer; W. R. Hussein; P. B. Tchounwou

2002-01-01

94

Exposure to Tetrachloroethylene-Contaminated Drinking Water and the Risk of Pregnancy Loss  

Microsoft Academic Search

There is little information on the impact of solvent-contaminated drinking water on pregnancy outcomes. This retrospective\\u000a cohort study examined whether maternal exposure to tetrachloroethylene (PCE)-contaminated drinking water in the Cape Cod region\\u000a of Massachusetts influenced the risk of clinically recognized pregnancy loss. The study identified exposed (n=959) and unexposed (1,087) women who completed a questionnaire on their residential and pregnancy

Ann Aschengrau; Janice M. Weinberg; Lisa G. Gallagher; Michael R. Winter; Veronica M. Vieira; Thomas F. Webster; David M. Ozonoff

2009-01-01

95

Spontaneous abortions and congenital malformations among women exposed to tetrachloroethylene in dry cleaning.  

PubMed Central

STUDY OBJECTIVE: The aim of the study was to determine whether exposure to tetrachloroethylene during the first trimester of pregnancy has harmful effects on pregnancy outcome. DESIGN: The study used record linkage identification of cases and case-control comparison. SETTING: The study involved dry cleaner and laundry workers throughout Finland who had become pregnant during the study period. Controls were age matched but otherwise unselected women giving birth to normal babies in the study period. SUBJECTS: Cases were defined as women who had been treated for spontaneous abortion or had delivered a malformed child. Out of 5700 workers nearly half had been pregnant during the study period. One pregnancy only was randomly selected for study per worker, and the final study population was 247 women with spontaneous abortions and 33 with malformed infants. Three age matched controls were selected for each abortion case and five for each malformation case. MEASUREMENTS AND MAIN RESULTS: Three women out of four had worked in early pregnancy. Exposure information was collected from 1108 women by mailed questionnaires, with a 77% response, and was partly confirmed by biological monitoring data. Exposure to tetrachloroethylene was found to be significantly associated with spontaneous abortions (odds ratio 3.6, p less than 0.05). CONCLUSION: The findings, together with other available data, indicate that exposure of pregnant women to tetrachloroethylene needs to be minimised.

Kyyronen, P; Taskinen, H; Lindbohm, M L; Hemminki, K; Heinonen, O P

1989-01-01

96

Subchronic toxicity of tetrachloroethylene (perchloroethylene) administered in the drinking water of rats  

SciTech Connect

This study provides data on the effects of tetrachloroethylene in drinking solutions. The acute oral LD50 in male and female Charles River rats was found to be 3835 mg/kg for males and 3005 mg/kg for females. Male and female rats received theoretical daily doses of 14,400, and 1400 mg tetrachloroethylene/kg body wt/day for 90 consecutive days. There were no compound-related deaths. Body weights were significantly lower in male and female rats at the higher doses. There were no consistent dose-related effects on any of the hematological, clinical chemistry, or urinalysis parameters. 5'-Nucleotidase activity was increased in a dose-dependent manner, suggesting possible hepatotoxicity; however, other serum indicators of hepatic function were unaffected by the treatment. There were no gross pathological effects observed. Liver and kidney body weight ratios, but not brain weight ratios, were elevated at the higher doses. There was no other evidence of compound-related toxicity. These data suggest that exposure of humans to reported levels of tetrachloroethylene in drinking water (approximately 1 microgram/liter) does not constitute a serious health hazard.

Hayes, J.R.; Condie, L.W. Jr.; Borzelleca, J.F.

1986-07-01

97

Metabolic acidosis in toluene sniffing.  

PubMed

ABSTRACTToluene sniffing, frequently described under the generic category of "glue sniffing," is a potential cause of normal anion gap metabolic acidosis due to distal renal tubular acidosis. Urine anion gap is used to diagnose metabolic acidosis of a normal anion gap variety; however, pitfalls exist when using urine anion gap in the setting of toluene sniffing. We present the case of a young woman who had a normal anion gap metabolic acidosis due to toluene sniffing and an unexpectedly low urine anion gap. In such a scenario, the urine anion gap will underestimate the rate of ammonia excretion when the conjugate bases of acids other than HCl are excreted in large quantities. Estimation of the urine osmolal gap will provide a more accurate ammonia excretion rate in these circumstances. The challenges in interpretation of the urine anion gap and ammonia excretion in the setting of distal renal tubular acidosis due to toluene toxicity are discussed. PMID:23778000

Tuchscherer, Jon; Rehman, Habib

2013-07-01

98

Decomposition of dilute trichloroethylene by nonthermal plasma  

SciTech Connect

Decomposition performance of a dilute toxic organic compound, trichloroethylene (TCE), in air by using nonthermal plasma processing was studied extensively. The nonthermal plasma was generated by the high-frequency (2 kHz) or commercial-frequency (50 Hz) barrier discharge in a fused silica tube. Three types of reactors, bolt type, rod type (both are barrier-discharge type), and coil type (surface-discharge type), were tested. Analysis of byproducts, residual materials, and end products generated by the plasma process was performed by a gas chromatography mass spectrometer of gas chromatography. Most organic byproducts decrease with an increase of the electric discharge power, but only toxic phosgene increases with the increase of the discharge power. As a post process, NaOH solution was used to test effluent from the plasma reactor. The solution was found effective in phosgene absorption. Comparison between nonthermal plasma and UV irradiation for TCE decomposition was also made. In regard to the energy efficiency of the TCE decomposition, UV irradiation is found much better than discharge plasma.

Oda, Tetsuji; Takahashi, Tadashi; Tada, Keiko [Univ. of Tokyo (Japan). Dept. of Electrical Engineering

1999-03-01

99

Persulfate regeneration of trichloroethylene spent activated carbon.  

PubMed

The objective of this study was to demonstrate the regeneration of trichloroethylene (TCE) spent activated carbon using persulfate oxidation and iron activated persulfate (IAP) oxidation. Both processes resulted in decreases in the adsorbability of regenerated activated carbons. IAP was shown to rapidly degrade the aqueous TCE and causes a significant mineralization of the TCE. The release of chloride ions provided evidence of this. Persulfate oxidation mainly resulted in desorption of TCE from the activated carbon and only partial mineralization of the TCE through a carbon activated persulfate reaction mechanism. Concerning destruction of the TCE, in the regeneration test using persulfate, 30% of the original TCE was present in the solution and 9% remained on the activated carbon after the first regeneration cycle. In contrast, in the test that used IAP, it was observed that no TCE was present in the solution and only approximately 5% of the original TCE remained on the activated carbon after the first regeneration. Following the regeneration cycles, elemental analysis was carried out on the samples. BET surface area and EDS analysis showed some effects on the physico-chemical properties of the activated carbon such as a slight decrease in the surface area and the presence of iron precipitates on the carbon. PMID:19264399

Liang, Chenju; Lin, Ya-Ting; Shin, Wu-Hang

2009-02-12

100

The Decomposition of Toluene by Soil Bacteria  

Microsoft Academic Search

SUMMARY Strains of two bacteria, a Pseudomonas and an Achromobacter, which grow with toluene, benzene or certain other related aromatic com- pounds as sole carbon source were isolated from soil. The use of aromatic compounds by these bacteria was an induced phenomenon. Toluene-grown organisms oxidized without lag toluene, benzene, catechol, &methyl- catechol, benzyl alcohol and, more slowly, o- and m-cresol,

D. Claus; N. Walker

1964-01-01

101

NEUROBEHAVIORAL EFFECTS OF TOLUENE: A REVIEW  

EPA Science Inventory

Toluene appears to produce reversible effects upon liver, renal and nervous systems. Its usual route of intake is via respiration. The nervous system appears to be the most sensitive to the effects of toluene. Although there are few studies of toluene's neurotoxicity, some tenuou...

102

Trichloroethylene risk assessment: a review and commentary.  

PubMed

Trichloroethylene (TCE) is a widespread environmental contaminant that is carcinogenic when given in high, chronic doses to certain strains of mice and rats. The capacity of TCE to cause cancer in humans is less clear. The current maximum contaminant level (MCL) of 5 ppb (microg/L) is based on an US Environment Protection Agency (USEPA) policy decision rather than the underlying science. In view of major advances in understanding the etiology and mechanisms of chemically induced cancer, USEPA began in the late 1990s to revise its guidelines for cancer risk assessment. TCE was chosen as the pilot chemical. The USEPA (2005) final guidelines emphasized a "weight-of-evidence" approach with consideration of dose-response relationships, modes of action, and metabolic/toxicokinetic processes. Where adequate data are available to support reversible binding of the carcinogenic moiety to biological receptors as the initiating event (i.e., a threshold exists), a nonlinear approach is to be used. Otherwise, the default assumption of a linear (i.e., nonthreshold) dose-response is utilized. When validated physiologically based pharmacokinetic (PBPK) models are available, they are to be used to predict internal dosimetry as the basis for species and dose extrapolations. The present article reviews pertinent literature and discusses areas where research may resolve some outstanding issues and facilitate the reassessment process. Key research needs are proposed, including role of dichloroacetic acid (DCA) in TCE-induced liver tumorigenesis in humans; extension of current PBPK models to predict target organ deposition of trichloroacetic acid (TCA) and DCA in humans ingesting TCE in drinking water; use of human hepatocytes to ascertain metabolic rate constants for use in PBPK models that incorporate variability in metabolism of TCE by potentially sensitive subpopulations; measurement of the efficiency of first-pass elimination of trace levels of TCE in drinking water; and assessment of exogenous factors' (e.g., alcohol, drugs) ability to alter metabolic activation and risks at such low-level exposure. PMID:19852561

Jollow, David J; Bruckner, James V; McMillan, David C; Fisher, Jeffrey W; Hoel, David G; Mohr, Lawrence C

2009-01-01

103

Fate and Disposition of Trichloroethylene in Surface Soils.  

National Technical Information Service (NTIS)

Trichloroethylene (TCE) is a widely detected contaminant in groundwater. This study investigated fate of TCE in two similar soils with differing organic carbon contents. TCE was applied to soil columns in one 5 or 10 m1 quantity, then eluted with 50 or 10...

T. J. Walker

1984-01-01

104

Biotransformation of trichloroethylene by a phenol-induced mixed culture  

Microsoft Academic Search

Biodegradation of trichloroethylene (TCE) was studied using a mixed culture of aerobic, phenol-induced organisms. Abiotic experiments showed that sorption of TCE to biomass was negligible in the systems studied. The effects of influent phenol and TCE concentration on the TCE degradation capacity of the culture were studied using chemostats. A relationship exists between the influent phenol\\/TCE ratio and TCE biodegradation.

Mathew M. Shurtliff; Gene F. Parkin; D. T. Gibson; L. J. Weathers

1996-01-01

105

Sonolysis of an aqueous mixture of trichloroethylene and chlorobenzene  

Microsoft Academic Search

The effect of the initial concentration on the ultrasonic degradation of two volatile organic compounds trichloroethylene (TCE) and chlorobenzene (CB) was investigated. At higher concentrations, slower sonolysis rates were obtained due to the lowering of the average specific heat ratio ? of the gas inside the cavitation bubbles. Furthermore, the effect of different concentrations of CB on the sonolysis of

D. Drijvers; H. van Langenhove; L. Nguyen Thi Kim; L. Bray

1999-01-01

106

USE OF GRANULAR GRAPHITE FOR ELECTROLYTIC DECHLORINATION OF TRICHLOROETHYLENE  

EPA Science Inventory

Granular graphite is a potential electrode material for the electrochemical remediation of refractory chlorinated organic compounds such as trichloroethylene (TCE). However, the use of granular graphite can complicate the experimental results. On one hand, up to 99% of TCE was re...

107

EFFECTS OF TRICHLOROETHYLENE EXPOSURE ON MALE REPRODUCTIVE FUNCTION IN RATS  

EPA Science Inventory

The present study was designed to evaluate the influences of trichloroethylene (TCE) on the reproductive system of male rats. In addition, information was obtained on the distribution and metabolism of TCE. At 100 days of age, male rats were allowed to copulate with ovariectomize...

108

Chronic dysphagia and trigeminal anesthesia after trichloroethylene exposure  

SciTech Connect

A patient is described who inhaled trichloroethylene fumes while working in a closed underground pit. At the time of exposure he developed dysphagia, dysarthria and dyspnea. Assessment of his condition 11 years after the incident indicated major damage of cranial nerves, particularly the trigeminal, chronic involvement of the bulbar cranial nerves, and resultant esophageal and pharnygeal motility impairment. (JMT)

Lawrence, W.H.; Partyka, E.K.

1981-12-01

109

EFFECTS OF ORAL EXPOSURE TO TRICHLOROETHYLENE ON FEMALE REPRODUCTIVE FUNCTION  

EPA Science Inventory

In the present study, the distribution, metabolism and reproductive toxicity of trichloroethylene (TCE) administered by the oral route to female rats were examined. The distribution study with 14C-TCE indicated that relatively high levels of radioactivity accumulated in the ovary...

110

PBPK modeling of the metabolic interactions of carbon tetrachloride and tetrachloroethylene in B6C3F1 mice  

Microsoft Academic Search

Potential exists for widespread human exposure to low levels of carbon tetrachloride (CT) and tetrachloroethylene (TET). These halocarbons are metabolized by the cytochrome P450 system. CT is known to inhibit its own metabolism (suicide inhibition) and to cause liver injury by generation of metabolically derived free radicals. The objective of this research was to use develop a physiologically based pharmacokinetic

J Fisher; M Lumpkin; J Boyd; D Mahle; J. V Bruckner; H. A El-Masri

2004-01-01

111

Preparation of carbon foams with supercritical toluene  

Microsoft Academic Search

Carbon foams with pore sizes of 10–50 ?m were prepared with mesophase pitch and toluene as the carbonaceous precursor and\\u000a supercritical agent, respectively. Results revealed that the light pitch components and dissolved toluene in pitch significantly\\u000a affected the pore structures of resultant carbon foams. The amount of toluene dissolved in molten pitch is greatly dependent\\u000a on the foaming conditions, such as

Juan Li; Can Wang; Guo Cheng; Yan-Li Wang; Liang Zhan; Wen-Ming Qiao; Li-Cheng Ling

2010-01-01

112

Effect of carbon starvation on toluene degradation activity by toluene monooxygenase-expressing bacteria  

Microsoft Academic Search

Subsurface bacteria commonly exist in a starvation state with only periodic exposure to utilizable sources of carbon and energy. In this study, the effect of carbon starvation on aerobic toluene degradation was quantitatively evaluated with a selection of bacteria representing all the known toluene oxygenase enzyme pathways. For all the investigated strains, the rate of toluene biodegradation decreased exponentially with

David R. Johnson; Jerome J. Kukor; Linda M. Abriola

2006-01-01

113

Estimating amounts of toluene inhaled by workers with protective mask using biological indicators of toluene  

Microsoft Academic Search

Personal air samplers were attached to workers wearing protective masks to determine the levels of toluene vapor in the breathing zone. Concentrations of toluene in exhaled air, blood and urine; and hippuric acid and o-cresol concentrations in the urine of the workers were determined. Subsequently, toluene concentrations in the air inhaled by workers with and without gas masks were estimated

Masana Ogata; Hiromi Michitsuji; Yukio Fujiki

1999-01-01

114

Simulation calculations of tetrachloroethylene decomposition in air mixtures under electron beam irradiation  

NASA Astrophysics Data System (ADS)

Theoretical simulation calculations of tetrachloroethylene (PCE) decomposition in air mixtures under electron beam (EB) irradiation have been carried out based on the experimental results. A computer code Kinetic and a Gear method were used and 324 reactions and 76 species were considered. From calculated results, we learn that more than 99% PCE is decomposed at 4.4 kGy dose when the initial concentration of PCE is 322 ppm; concentrations of inorganic carbons (CO+CO2) increases with the dose, and the relative carbon concentration of inorganic carbons is about 17% at 13.1 kGy; phosgene (COCl2) and trichloroacetyl chloride (CCl3COCl) are predicted as main organic products and are confirmed by the experimental results. The good agreement is obtained between the calculated results and the experimental data.

Sun, Y.; Chmielewski, A. G.; Bu?ka, S.; Zimek, Z.; Nichipor, H.

2009-07-01

115

Factors affecting the adsorption of trichloroethylene onto activated carbons  

Microsoft Academic Search

In this work, an experimental study aimed at the assessment of the factors affecting the adsorption of trichloroethylene (TCE) from water solutions onto activated carbons is presented. The influence of sorbent properties, such as B.E.T. surface area, micropore volume, chemical composition and acid\\/basic surface functional groups on TCE adsorption capacity is experimentally assessed by testing a set of 12 sorbents.

A. Erto; R. Andreozzi; A. Lancia; D. Musmarra

2010-01-01

116

Physiological pharmacokinetic modeling of inhaled trichloroethylene in rats  

Microsoft Academic Search

The pharmacokinetics of trichloroethylene (TCE) was characterized during and following inhalation exposures of male Sprague-Dawley rats. The blood and exhaled breath TCE time-course data were used to formulate and assess the accuracy of predictions of a physiologically based pharmacokinetic (PB-PK) model for TCE inhalation. Fifty or 500 ppm TCE was inhaled by unanesthetized rates of 325-375g for 2 hrs through

C. E. Dallas; J. M. Gallo; R. Ramanathan; S. Muralidhara; J. V. Bruckner

1991-01-01

117

Trichloroethylene biodegradation by a methane-oxidizing bacterium  

Microsoft Academic Search

Trichloroethylene (TCE), a common ground water contaminant, is a suspected carcinogen that is highly resistant to aerobic biodegradation. An aerobic, methane-oxidizing bacterium was isolated that degrades TCE in pure culture at concentrations commonly observed in contaminated ground water. Strain 46-1, a type I methanotrophic bacterium, degraded TCE if grown on methane or methanol, producing COâ and water-soluble products. Gas chromatography

C. D. Little; A. V. Palumbo; S. E. Herbes; M. E. Lidstrom; R. L. Tyndall; P. J. Gilmer

1988-01-01

118

Trichloroethylene effects on gene expression during cardiac development  

Microsoft Academic Search

Background: Halogenated hydrocarbon exposure is associated with changes in gene expression in adult and embryonic tissue. The present study was undertaken to identify differentially expressed mRNA transcripts in embryonic hearts from Sprague-Dawley rats exposed to trichloroethylene (TCE) or potential bio-transformation products of TCE, Dichloroethylene (DCE) and Trichloroacetic acid (TCAA). Methods: cDNA subtractive hybridization was used to selectively amplify expressed mRNA

John Michael Collier; Ornella Selmin; Paula D. Johnson; Raymond B. Runyan

2003-01-01

119

Effect of mineral media on trichloroethylene oxidation by aquifer methanotrophs  

Microsoft Academic Search

The effect of growth in different mineral media on subsequent oxidation of trichloroethylene (TCE) by type I and type II aquifer\\u000a methanotrophs was evaluated. Mixed culture MM1, containing a type II methanotroph, and a type I pure culture tentatively identified\\u000a as aMethylomonas sp., were enriched and isolated from an uncontaminated groundwater aquifer. The second-order rate coefficients (k\\/Ks) for TCE oxidation

Susan M. Henry; Dunja Grbic-Galic

1990-01-01

120

Aerobic Mineralization of Trichloroethylene, Vinyl Chloride, and Aromatic Compounds by Rhodococcus Species  

PubMed Central

Two Rhodococcus strains which were isolated from a trichloroethylene (TCE)-degrading bacterial mixture and Rhodococcus rhodochrous ATCC 21197 mineralized vinyl chloride (VC) and TCE. Greater than 99.9% of a 1-mg/liter concentration of VC was degraded by cell suspensions. [1,2-14C]VC was degraded by cell suspensions, with the production of greater than 66% 14CO2 and 20% 14C-aqueous phase products and incorporation of 10% of the 14C into the biomass. Cultures that utilized propane as a substrate were able to mineralize greater than 28% of [1,2-14C]TCE to 14CO2, with approximately 40% appearing in 14C-aqueous phase products and another 10% of 14C incorporated into the biomass. VC degradation was oxygen dependent and occurred at a pH range of 5 to 10 and temperatures of 4 to 35°C. Cell suspensions degraded up to 5 mg of TCE per liter and up to 40 mg of VC per liter. Propane competitively inhibited TCE degradation. Resting cell suspensions also degraded other chlorinated aliphatic hydrocarbons, such as chloroform, 1,1-dichloroethylene, and 1,1,1-trichloroethane. The isolates degraded a mixture of aromatic and chlorinated aliphatic solvents and utilized benzene, toluene, sodium benzoate, naphthalene, biphenyl, and n-alkanes ranging in size from propane to hexadecane as carbon and energy sources. The environmental isolates appeared more catabolically versatile than R. rhodochrous ATCC 21197. The data report that environmental isolates of Rhodococcus species and R. rhodochrous ATCC 21197 have the potential to degrade TCE and VC in addition to a variety of aromatic and chlorinated aliphatic compounds either individually or in mixtures.

Malachowsky, K. J.; Phelps, T. J.; Teboli, A. B.; Minnikin, D. E.; White, D. C.

1994-01-01

121

Toluene inhibits hippocampal neurogenesis in adult mice.  

PubMed

Toluene, a representative industrial solvent and abused inhalant, decreases neuronal activity in vitro and causes mental depression and cognitive impairment in humans. However, the effects of toluene on brain function and the sites of its action are poorly understood. This study investigated the temporal changes of neurogenesis in the hippocampus of adult C57BL/6 mice after acute administration of toluene using two immunohistochemical markers for neurogenesis, Ki-67 and doublecortin (DCX). In addition, after toluene treatment, depression-like behaviors and learning and memory tasks were examined to assess hippocampal neurogenesis-related behavioral dysfunction. The number of Ki-67- and DCX-positive cells in the dentate gyrus of adult hippocampi declined acutely between 0 h and 24 h after toluene treatment (500 mg/kg, i.p.) and increased gradually from 2 to 8 days post-administration. The level of Ki-67 and DCX immunoreactivity decreased in a dose-dependent manner within the range of toluene administered (0-1000 mg/kg). In tail suspension and forced-swim tests performed at 1 and 4 days after toluene treatment (500 mg/kg), mice showed significant depression-like behaviors compared to the vehicle-treated controls. In the contextual fear conditioning and object recognition memory test, the mice trained at 1 and 4 days after toluene treatment showed significant memory defects compared to the vehicle-treated controls. This study suggests that acute exposure to toluene reduces the rate of adult hippocampal neurogenesis and can cause hippocampal dysfunction such as depression and cognitive impairment. PMID:19969016

Seo, Heung-Sik; Yang, Miyoung; Song, Myoung-Sub; Kim, Joong-Sun; Kim, Sung-Ho; Kim, Jong-Choon; Kim, Heechul; Shin, Taekyun; Wang, Hongbing; Moon, Changjong

2009-12-05

122

Composition of Toluene-Degrading Microbial Communities from Soil at Different Concentrations of Toluene  

PubMed Central

Toluene-degrading bacteria were isolated from hydrocarbon-contaminated soil by incubating liquid enrichment cultures and agar plate cultures in desiccators in which the vapor pressure of toluene was controlled by dilution with vacuum pump oil. Incubation in desiccators equilibrated with either 100, 10, or 1% (wt/wt) toluene in vacuum pump oil and testing for genomic cross-hybridization resulted in four genomically distinct strains (standards) capable of growth on toluene (strains Cstd1, Cstd2, Cstd5, and Cstd7). The optimal toluene concentrations for growth of these standards on plating media differed considerably. Cstd1 grew best in an atmosphere equilibrated with 0.1% (wt/wt) toluene, but Cstd5 failed to grow in this atmosphere. Conversely, Cstd5 grew well in the presence of 10% (wt/wt) toluene, which inhibited growth of Cstd1. 16S ribosomal DNA sequencing and cross-hybridization analysis indicated that both Cstd1 and Cstd5 are members of the genus Pseudomonas. An analysis of the microbial communities in soil samples that were incubated with 10% (wt/wt) toluene with reverse sample genome probing indicated that Pseudomonas strain Cstd5 was the dominant community member. However, incubation of soil samples with 0.1% (wt/wt) toluene resulted in a community that was dominated by Pseudomonas strain Q7, a toluene degrader that has been described previously (Y. Shen, L. G. Stehmeier, and G. Voordouw, Appl. Environ. Microbiol. 64:637–645, 1998). Q7 was not able to grow by itself in an atmosphere equilibrated with 0.1% (wt/wt) toluene but grew efficiently in coculture with Cstd1, suggesting that toluene or metabolic derivatives of toluene were transferred from Cstd1 to Q7.

Hubert, Casey; Shen, Yin; Voordouw, Gerrit

1999-01-01

123

TRICHLOROETHYLENE ACCELERATES AN AUTOIMMUNE RESPONSE IN ASSOCIATION WITH TH1 T-CELL ACTIVATION IN MRL+/+ MICE. (R826409)  

EPA Science Inventory

Abstract Trichloroethylene (1,1,2-trichloroethene) is a major environmental contaminant. There is increasing evidence relating exposure to trichloroethylene with autoimmunity. To investigate potential mechanisms, we treated the autoimmune-prone MRL+/+ mice with trichlo...

124

Quantitative Evaluation of the Matabolic Interactions between Trichloroethylene and 1,1-Dichloroethylene In vivo Using Gas Uptake Methods,  

National Technical Information Service (NTIS)

Quantitative Evaluation of the Metabolic Interactions between Trichloroethylene and 1,1-Dichloroethylene in Vivo Using Gas Uptake Methods. Gas uptake simulation methods were used to determine kinetic constants for trichloroethylene (TCE) and 1,1-dichloroe...

M. E. Anderson M. L. Gargas H. J. Clewell K. M. Severyn

1987-01-01

125

Development of Binary Liquid-Vapor Phase Diagram Laboratory Procedures to Replace the Traditional Tetrachloroethylene\\/Cyclohexanone System  

Microsoft Academic Search

Two chemical systems were investigated and implemented as alternatives to the traditional tetrachloroethylene\\/cyclohexanone system used in the binary liquid-vapor phase diagram physical chemistry laboratory. Both the 2-butanone\\/cyclohexane and the ethyl acetate\\/cyclohexane systems reduce the cost of waste disposal and eliminate the use of chlorinated solvents. Student data showed that the azeotropic composition and temperature could be easily identified from a

Kelly J. Gordon; Laura Kenkel; Stephanie Prescia; Marcy Towns

126

A field experiment to study the behavior of tetrachloroethylene below the water table: Spatial distribution of residual and pooled DNAPL  

Microsoft Academic Search

This paper describes a field experiment involving the release of 230.9 liters of tetrachloroethylene (PCE) below the water table in a naturally occurring, unconfined sand aquifer. The release was executed in a 3m [times] 3m [times] 3.4m deep, sealable-joint steel sheet-pile cell anchored into an underlying clay aquitard. After allowing 28 days for redistribution, excavation of the upper approximately 0.9

B. H. Kueper; M. Mah; D. Redman; R. C. Starr; S. Reitsma

2009-01-01

127

Polydispersity of asphaltenes in toluene  

SciTech Connect

Asphaltenes have been reported to exhibit colloidal behavior in solutions. However, the thermodynamics of their self-association and the resulting particle polydispersity was not yet fully investigated. In this paper, the authors measured the structure and polydispersity of the asphaltene particles in toluene using small-angle neutron scattering (SANS). To study their self-association they systematically increased the solution temperature to observe the evolution, if any, of the particle structure and size. In order to determine the asphaltene size distribution and the corresponding polydispersity they fitted the SANS data with a polydispersity model in which one more adjustable parameter (than monodisperse analysis) was used to account for the particle size distribution. Because of one more free parameter used in data fitting, an ambiguous result due to multiple convergence may lead to a misinterpretation. In order to minimize this ambiguity and obtain a realistic particle size distribution they developed a method by which one can self-consistently verify the obtained particle size distribution. From SANS data analysis they found that the Schultz distribution function properly described the asphaltene particle sizes and the polydispersity decreases whenever temperature or concentration increases.

Sheu, E.Y.; Liang, K.S.; Sinha, S.K.; Overfield, R.E. (Exxon Research and Engineering Co., Annandale, NJ (United States))

1990-08-01

128

Process waste assessment: Petroleum jelly removal from semiconductor die using trichloroethylene  

SciTech Connect

The process analyzed involves non-production, laboratory environment use of trichloroethylene for the cleaning of semiconductor devices. The option selection centered on the replacement of the trichloroethylene with a non-hazardous material. This process waste assessment was performed as part of a pilot project.

Curtin, D.P.

1993-05-01

129

Triplet States of Liquid Benzene and Toluene.  

National Technical Information Service (NTIS)

The sensitization of biacetyl phosphorescence has been used to study the triplet states of benzene and toluene in the undiluted (neat) liquids. The results are not consistent with the expected triplet-triplet transfer and suggest that the transferring spe...

J. W. van Loben Sels J. T. Dubois

1966-01-01

130

Toxicokinetics of toluene in occupationally exposed volunteers.  

PubMed

The influence on the kinetics of toluene from long-term occupational exposure, cigarette smoking, and ethanol consumption was studied in 26 male spray painters. A group of spray painters with reported subjective symptoms such as concentration deficits, fatigue, and dizziness due to the solvent exposure did not differ in the uptake and disposition of toluene from a group of spray painters with no symptoms. In occupationally exposed workers, a tendency for an enhanced clearance of toluene from the blood was observed in relation to personal habits such as smoking and/or moderate chronic ethanol intake. Long-term occupational exposure to a mixture of organic solvents does not exert any effect on the metabolic rate of toluene as compared with that of an unexposed group. PMID:3823807

Wallén, M

1986-12-01

131

THE EFFECT OF LOW CONCENTRATIONS OF TETRACHLOROETHYLENE ON THE PERFORMANCE OF PEM FUEL CELLS  

SciTech Connect

Polymer electrolyte membrane (PEM) fuel cells use components that are susceptible to contaminants in the fuel stream. To ensure fuel quality, standards are being set to regulate the amount of impurities allowable in fuel. The present study investigates the effect of chlorinated impurities on fuel cell systems using tetrachloroethylene (PCE) as a model compound for cleaning and degreasing agents. Concentrations between 0.05 parts per million (ppm) and 30 ppm were studied. We show how PCE causes rapid drop in cell performances for all concentrations including 0.05 ppm. At concentrations of 1 and 0.05 ppm, PCE poisoned the cell at a rate dependent on the dosage of the contaminant delivered to the cell. PCE appears to affect the cell when the cell potential was over potentials higher than approximately 0.2 V. No effects were observed at voltages around or below 0.2 V and the cells could be recovered from previous poisoning performed at higher potentials. Recoveries at those low voltages could be induced by changing the operating voltage or by purging the system. Poisoning did not appear to affect the membrane conductivity. Measurements with long-path length IR results suggested catalytic decomposition of the PCE by hydrogen over the anode catalyst.

COLON-MERCHADO, H.; MARTINEZ-RODRIGUEZ, M.; FOX, E.; RHODES, W.; MCWHORTER, C.; GREENWAY, S.

2011-04-18

132

Determination of bioconcentration potential of tetrachloroethylene in marine algae by 13C.  

PubMed

The use of stable isotope of organic-carbon, organic-13C, as a tracer for the determination of the concentration of tetrachloroethylene (PCE), CA, in Heterosigma akashiwo and Skeletonema costatum was examined. CA determined by the 13C and GC methods showed good agreement with each other. This suggests that it is reasonable and reliable to determine the bioconcentration potential of PCE in marine algae. Fitting values of bioconcentration potential parameters, including uptake rate constant k1, elimination rate constant k2 and bioconcentration factor on the basis of dry weight BCFD, were done not only to the time course for PCE uptake by the algae with the bioconcentration model, but also to experimental data for "percent inhibition(%) approximately exposure concentration of PCE approximately time" with the combined bioconcentration and probability model. The values obtained from the bioconcentration model were consistent with those from the combined bioconcentration and probability model. With the parameters (such as k1, k2, growth rate constant kG, critical concentration of HOCs in the organism resulting in growth inhibition CA* and spread factor S) the variability in toxicity (such as EC10, EC50, EC70) can be estimated from the combined bioconcentration and probability model, which fits well with the experimental observations. PMID:8759313

Wang, X; Harada, S; Watanabe, M; Koshikawa, H; Sato, K; Kimura, T

1996-09-01

133

Tetrachloroethylene metabolism resulting from domestic respiratory exposure: Pharmacokinetic considerations relevant to risk assessment  

SciTech Connect

Physiologically based pharmacokinetic (PBPK) models describing the uptake, metabolism, and excretion of xenobiotic compounds are now proposed for use in regulatory health-risk assessments. In this study we compare how different scenarios for domestic respiratory exposure to tetrachloroethylene (PCE) from ground water influence the extent of PCE metabolism predicted using a PBPK model. Indoor exposure patterns we use as input to the PBPK model are realistic ones generated from a three-compartment model describing volatilization of PCE from domestic water into household air. Values we use for the metabolic parameters of the PBPK model are estimated from data on urinary metabolites in workers exposed to PCE. For respiratory PCE exposure due to typical levels of PCE in ground water, use of time-weighted average air concentrations with a steady-state PBPK model yields estimates of total metabolized PCE similar to those obtained using completely dynamic modeling, despite considerable uncertainty in key exposure and metabolic-model parameters. These findings suggest that, in this case, risk estimation taking pharmacokinetics into account may be accomplished using simple analytic methods. 31 refs., 8 figs., 3 tabs.

Bogen, K.T.; McKone, T.E.

1987-10-01

134

Continuous determination of high-vapor-phase concentrations of tetrachloroethylene using on-line mass spectrometry.  

PubMed

A method was developed to determine the vapor concentration of tetrachloroethylene (PCE) at and below its equilibrium vapor-phase concentration, 168 000 microg/L (25 degrees C). Vapor samples were drawn by vacuum into a six-port sampling valve and injected through a jet separator into an ion trap mass spectrometer (MS). This on-line MS can continuously sample a vapor stream and provide vapor concentrations every 30 s. Calibration of the instrument was done by creating a saturated stream of PCE vapor, sampling the vapor with the on-line MS and with thermal desorption tubes, and correlating the peak area response from the MS with the vapor concentration determined by automated thermal desorption gas chromatography mass spectrometry. Dilution of the saturated stream provided lower concentrations of PCE vapor. The method was developed to monitor the vapor concentration of PCE that was sparged from a two-dimensional flow chamber and for determination of the total PCE mass removed during each sparge event. The method has potential application for analysis of gas-phase tracers. PMID:18205332

Fine, Dennis; Brooks, Michael C; Bob, Mustafa; Mravik, Susan; Wood, Lynn

2008-01-19

135

A risk-based cleanup criterion for PCE in soil. [Tetrachloroethylene  

SciTech Connect

The most important attribute of a chemical contaminant at a hazardous-wastes site for decision makers to consider with regard to its cleanup is the potential risk associated with human exposure. For this reason we have developed a strategy for establishing a risk-based cleanup criterion for chemicals in soil. We describe this strategy by presenting a cleanup criterion for tetrachloroethylene (PCE) in soil associated with a representative California landscape. We being by discussing the environmental fate and transport model, developed at the Lawrence Livermore National Laboratory (LLNL), that we used to predict the equilibrium concentration of PCE in five environmental media from a steady-state source in soil. Next, we explain the concept and application of pathway-exposure factors (PEFs), the hazard index, and cancer-potency factors (CPFs) for translating the predicted concentrations of PCE into estimated potential hazard or risk for hypothetically exposed individuals. Finally, the relationship between concentration and an allowable level of risk is defined and the societal and financial implications are discussed. 22 refs., 6 tabs.

Daniels, J.I.; McKone, T.E.; Hall, L.C.

1990-09-26

136

Adult neuropsychological performance following prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water.  

PubMed

This population-based retrospective cohort study examined adult performance on a battery of neuropsychological tests in relation to prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using pipe network information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling software, and a Geographic Information System (GIS). Results of crude and multivariate analyses among 35 exposed and 28 unexposed subjects showed no association between prenatal and early postnatal exposure and decrements on tests that assess abilities in the domains of omnibus intelligence, academic achievement or language. The results were suggestive of an association between prenatal and early postnatal PCE exposure and diminished performance on tests that assessed abilities in the domains of visuospatial functioning, learning and memory, motor, attention and mood. Because the sample size was small, most findings were not statistically significant. Future studies with larger sample sizes should be conducted to further define the neuropsychological consequences of early developmental PCE exposure. PMID:22522125

Janulewicz, Patricia A; White, Roberta F; Martin, Brett M; Winter, Michael R; Weinberg, Janice M; Vieira, Veronica; Aschengrau, Ann

2012-04-12

137

Modeling of TCE and Toluene Toxicity to Pseudomonas putida F1  

NASA Astrophysics Data System (ADS)

Prediction of viable bacterial distribution with respect to contaminants is important for efficient bioremediation of contaminated ground-water aquifers, particularly those contaminated with residual NAPLs. While bacterial motility and chemotaxis may help situate bacteria close to high concentrations of contaminant thereby enhancing bioremediation, prolonged exposure to high concentrations of contaminates is toxic to contaminant-degrading bacteria. The purpose of this work is to model the toxicity of trichloroethylene and toluene to Pseudomonas putida F1. The Live/Dead® bacterial viability assay was used to determine the toxic effect of chemical contaminants on the viability of P. putida F1 in a sealed zero head-space experimental environment. Samples of bacterial suspensions were exposed to common ground-water pollutants, TCE and toluene, for different durations. Changes in live and dead cell populations were monitored over the course of experiments using fluorescence microscopy. Data obtained from these toxicity experiments were fit to simple linear and exponential bacterial decay models using non-linear regression to describe loss of bacterial viability. TCE toxicity to P. putida F1 was best described with an exponential decay model (Figure 1a), with a decay constant kTCE = 0.025 h-4.95 (r2 = 0.956). Toluene toxicity showed a marginally better fit to the linear decay model (Figure 1b) (r2 = 0.971), with a decay constant ktoluene = 0.204 h-1. Best-fit model parameters obtained for both TCE and toluene were used to predict bacterial viability in toxicity experiments with higher contaminant concentrations and matched well with experimental data. Results from this study can be used to predict bacterial accumulation and viability near NAPL sources, and thus may be helpful in improving bioremediation performance assessment of contaminated sites. Figure 1: Survival ratios (S = N/No) of P. putida F1 in TCE- (a) and toluene- (b) stressed samples (observed (‘x’), linear model (‘—’) and exponential model (‘---’)) and non-TCE stressed samples (‘o’) at different time intervals throughout toxicity experiments. Error bars represent standard errors for five replicate experiments.

Singh, R.; Olson, M. S.

2009-12-01

138

ACTIVITY COEFFICIENTS OF CARBAMOYLMETHYLPHOSPHORYL EXTRACTANTS IN TOLUENE  

Microsoft Academic Search

The activity coefficients of four extractants belonging to the carbamoylmethylphosphoryl class were measured by vapor-phase osmometry. All of the activity coefficients were within 15% of unity for concentrations up to 0.5 M in toluene. As the basicity of the extractant's phosphoryl-group increases, its activity coefficient decreases. Octylphenyl-N,N-diisobutylcarbamoylmethyl-phosphine oxide [O?D(iB)CMPO] in toluene exhibited a marked decrease in activity coefficient upon equilibration

H. Diamond; E. P. Horwitz; P. R. Danesi

1986-01-01

139

Carbon doping of MgB2 by toluene and malic-acid-in-toluene  

NASA Astrophysics Data System (ADS)

The decomposition of malic acid (C4H6O5) in the presence of Mg and B was studied using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) which revealed that malic acid reacted with Mg but not B. Also, the addition of toluene (C7H8) to dissolve malic acid followed by subsequent drying resulted in no reaction with Mg, indicating that the malic acid had decomposed during the dissolution/drying stage. The total carbon contributed by toluene versus a toluene/5 wt.% malic acid mixture was measured using a LECO CS600 carbon analyzer. The toluene sample contained ˜0.4 wt.% C while the toluene/malic acid mixture had ˜1.5 wt.% C, demonstrating that the toluene contributed a significant amount of carbon to the final product. Resistivity measurements on powder-in-tube MgB2 monofilamentary wires established that the toluene/malic acid doped sample had the highest Bc2. However, the toluene-only sample had the highest transport Jc over most of the magnetic field range (0-9 T), equaled only by that of toluene/malic-acid sample in fields above 9 T.

Bohnenstiehl, S. D.; Susner, M. A.; Yang, Y.; Collings, E. W.; Sumption, M. D.; Rindfleisch, M. A.; Boone, R.

2011-02-01

140

Menstrual function in workers exposed to toluene.  

PubMed Central

Rates of menstrual disorders were studied in 231 female production workers with high exposure to toluene (mean 88 (range 50-150 ppm) in a factory manufacturing audio speakers and compared with a control group of 58 female production workers in other departments in the same factory who had little or no exposure to toluene (0-25 ppm). An external community control group of 187 working class women under routine care at public maternal and child health centres were also studied. Detailed menstrual and reproductive histories were obtained by personal interview using a structured questionnaire. The rates for dysfunctional uterine bleeding (cycle irregularity and prolonged or heavy menstrual bleeding) were similar in all groups. Dysmenorrhoea seemed to occur more often in the women highly exposed to toluene compared with women at maternal and child health centres, but not compared with factory controls with low exposure to toluene. There was no evidence that dysfunctional uterine bleeding was likely to result from exposure to toluene. It is uncertain whether dysmenorrhoea was associated specifically with exposure to toluene, as other behavioural and work related factors may also result in dysmenorrhoea.

Ng, T P; Foo, S C; Yoong, T

1992-01-01

141

Toluene-induced ototoxicity by subcutaneous administration  

SciTech Connect

Inhalation exposure of rats to toluene causes irreversible hearing loss (e.g., Pryor et al.). To determine whether noise emanating from the inhalation system was a major contributing factor and whether exposure by a noninhalation route would cause a similar effect, weanling, male Fischer-344 rats were injected SC twice daily in a quiet environment with PEG-300 (control) or with 1.5 or 1.7 g/kg of toluene for 7 days. After being trained to perform a multisensory conditioned avoidance response (CAR) task, tone intensity-response functions were generated at 4, 8, 12, and 20 kHz, and behavioral auditory response thresholds were estimated. Toluene caused a dose-related hearing loss at frequencies of 8 kHz and above, with no effect on performance of the CAR in response to light, nonaversive footshock, or the 4-kHz tone. The similarity of this effect to that observed following inhalation exposure indicates that noise is not a major factor in the toluene-induced hearing loss, although possible interactions between noise and toluene remain to be investigated. These results also demonstrate that direct penetration of the toluene vapors through the external ear structure, as might occur during inhalation exposure, is not a necessary condition for inducing the hearing loss.

Pryor, G.T.; Howd, R.A.

1986-01-01

142

Constitutive expression of the cloned phenol hydroxylase gene(s) from Alcaligenes eutrophus JMP134 and concomitant trichloroethylene oxidation.  

PubMed Central

Given the demonstrated phenol-dependent trichloroethylene (TCE) degradation in Alcaligenes eutrophus JMP134 (A. R. Harker and Y. Kim, Appl. Environ. Microbiol. 56:1179-1181, 1990), this work represents a purposeful effort to create a constitutive degrader of TCE. Genes responsible for phenol hydroxylase activity were identified by Tn5 transposon mutagenesis. Mutants lacked both phenol hydroxylase and catechol 2,3-dioxygenase activities. Southern blot analysis of total DNA showed that all mutants contained a single copy of Tn5 inserted in the same 11.5-kb EcoRI fragment. Complementation with a cosmid-based gene bank constructed from A. eutrophus AEK101 allowed the isolation of three recombinant cosmids carrying a common 16.8-kb HindIII fragment. Deletion and subcloning analysis localized the genes involved in phenol hydroxylase and catechol 2,3-dioxygenase activities. Partial sequence analysis of regions within the cloned phenol hydroxylase-expressing fragment shows significant homology to the oxygenase and oxidoreductase subunits of toluene-3-monooxygenase from Pseudomonas pickettii. The Tn5-induced phl mutant, carrying a recombinant plasmid expressing the phenol hydroxylase activity, degrades TCE in the absence of induction. Complete removal of TCE (50 microM) within 24 h was observed in minimal medium containing only 0.05% ethanol as a carbon source. The bacterium removed 200 microM TCE to below detectable levels within 2 days under noninducing and nonselective conditions.

Kim, Y; Ayoubi, P; Harker, A R

1996-01-01

143

TOLUENE BLOOD LEVEL FOLLOWING SUBCUTANEOUS INJECTION OF TOLUENE IN THE RAT  

EPA Science Inventory

A model of toluene level in blood following subcutaneous injection of toluene mixed with polyoxyethylated-vegetable-oil vehicle was developed. The purpose was to provide a means of predicting dose received for subsequent toxicologic studies for any time and dose combination. The ...

144

The selective catalytic oxidation of toluene  

NASA Astrophysics Data System (ADS)

It was found for the first time that the selectivity of toluene transformations into benzaldehyde and benzoic acid decreased and into maleic anhydride and deep oxidation products increased as the ability of vanadium-containing catalysts of toluene oxidation to generate the singlet form of molecular oxygen grew. A scheme of the formation of the products of toluene oxidation with oxygen was suggested. Quinones were shown to be final rather than intermediate oxidation products. The selectivity of the reaction with respect to mild oxidation products in the presence of V2O5, MoO3, and V2O5 · MoO3 could be increased by changing the temperature of catalyst preparation from 400 to 500°C.

Boikov, E. V.; Vishnetskaya, M. V.; Emel'Yanov, A. N.; Tomskii, I. S.; Shcherbakov, N. V.

2008-12-01

145

On the atmospheric oxidation of liquid toluene.  

PubMed

This communication presents preliminary computational results on the interaction between triplet (3Sigma) and singlet (1Sigma, 1Delta) oxygen molecules with toluene. All three oxygen species form very weak complexes with toluene and all also appear capable of abstracting a benzylic hydrogen atom to form the HO2 radical. Reaction with singlet molecular oxygen does not convincingly explain the formation of benzylhydroperoxide from toluene residues stored over a long time in brown glass bottles, and it is speculated that this may be a surface-catalysed photochemical reaction. The possible involvement of singlet oxygen molecules in the spontaneous ignition of tyre rubber and of soft coal is discussed briefly and the need for new experimental studies is stressed. PMID:17047753

Pritchard, Huw O

2006-09-12

146

Isobaric vapor-liquid equilibria of tetrachloroethylene + 1-propanol and + 2-propanol at 20 and 100 kPa  

SciTech Connect

Isobaric vapor-liquid equilibria were obtained for tetrachloroethylene + 1-propanol and +2-propanol systems at 20 and 100 kPa using a dynamic still. The experimental error in temperature was {+-} 0.1 K, in pressure {+-} 0.01 kPa and {+-} 0.1 kPa for the experiments carried out at 20 and 100 kPa, respectively, and in liquid and vapor composition 0.001. The two systems satisfy the point-to-point thermodynamic consistency test. Both systems show a positive deviation from ideality. The data were well correlated with the Wilson equation.

Dejoz, A.; Gonzalez-Alfaro, V.; Miguel, P.J.; Vazquez, M.I. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1996-11-01

147

Lipid peroxidation induced by trichloroethylene in rat liver  

SciTech Connect

It is well-known that trichloroethylene (TRI) is metabolized by cytochrome P-450 to TRI oxide, which binds irreversibly to cell macromolecules to generates hepatic damage. TRI oxide was metabolized to Chloral and Chloral hydrate, as an intramolecular rearrangement product of TRI oxide. However, recent studies have demonstrated that TRI oxide is not an obligate intermediate in the conversion of TRI to chloral. Therefore, there is no satisfactory explanation about the hepatic toxicity of TRI. On the other hand, the hepatic toxicity of halogenated compounds, may be closely related to lipid peroxidation, TRI enhances carbon tetrachloride hepatotoxicity in association with lipid peroxidation. In this report, the authors studied the effect of TRI on lipid peroxidation in vivo and in vitro.

Ogino, Keiki; Hobara, Tatuya; Kobayashi, Haruo; Ishiyama, Hironobu; Gotoh, Masayuki; Imamura, Akihisa; Egami, Norio (Yamaguchi Univ. (Japan))

1991-03-01

148

Dioxinlike properties of a trichloroethylene combustion-generated aerosol  

SciTech Connect

Conventional chemical analyses of incineration by-products identify compounds of known toxicity but often fail to indicate the presence of other chemicals that may pose health risks. In a previous report, extracts from soot aerosols formed during incomplete combustion of trichloroethylene (TCE) and pyrolysis of plastics exhibited a dioxinlike response when subjected to a keratinocyte assay. To verify this dioxinlike effect, the complete extract, its polar and nonpolar fractions, some containing primarily halogenated aromatic hydrocarbons, were evaluated for toxicity using an embryo assay, for antiestrogenicity using primary liver cell cultures, and for the ability to transform the aryl hydrocarbon receptor into its DNA binding form using liver cytosol in a gel retardation assay. Each of these assays detect dioxinlike effects. Medaka (Oryzias latipes) embryos and primary liver cell cultures of rainbow trout (Oncorhynchus mykiss) were exposed to concentrations of extract ranging from 0.05 to 45 {mu}g/l. 67 refs., 7 figs., 3 tabs.

Villalobos, S.A.; Anderson, M.J.; Hinton, D.E. [Univ. of California, Davis, CA (United States)] [and others

1996-07-01

149

Performance Characterization of a Model Bioreactor for the Biodegradation of Trichloroethylene by 'Pseudomonas cepacia' G4.  

National Technical Information Service (NTIS)

Of the volatile organic chemicals present in common groundwater contaminants, trichloroethylene (TCE) is the one most commonly found. TCE has been shown to be biodegraded by axenic cultures of aerobic organisms. Pseudomonas cepacia G4 grown in chemostats ...

B. R. Folsom P. J. Chapman

1991-01-01

150

Micellar Enhanced Ultrafiltration for Recovery and Concentration of Trichloroethylene in Groundwater.  

National Technical Information Service (NTIS)

The objective of this experimental investigation was to determine the feasability of micellar-enhanced ultrafiltration (MEUF) and vacuum stripping process in concentrating and separating trichloroethylene (TCE) from contaminated groundwater. The theory is...

B. L. Roberts J. F. Scamehorn S. D. Christian E. E. Tucker H. Uchiyama

1992-01-01

151

New perspectives on the cancer risks of trichloroethylene, its metabolites, and chlorination by-products.  

National Technical Information Service (NTIS)

Scientific developments in the 1990's have important implications for the assessment of cancer risks posed by exposures to trichloroethylene (TCE). These new developments include: epidemiological studies; experimental studies of TCE carcinogenicity, metab...

K. T. Bogen T. Slone L. S. Gold N. Manley K. Revzan

1994-01-01

152

PHENOL AND TRICHLOROETHYLENE DEGRADATION BY PSEUDOMONAS CEPACIA STRAIN G4: KINETICS AND INTERACTIONS BETWEEN COMETABOLITES  

EPA Science Inventory

Intact cells of pseudomonas cepacia strain G4 completely degraded trichloroethylene (TCE) following growth with phenol. egradation kinetics were determined for both phenol, used to induce requisite enzymes, and TCE, the target substrate. pparent Ks and Vmax values for degradation...

153

PHYSIOLOGICALLY BASED PHARMACOKINEITC (PBPK) MODELING OF METABOLIC INHIBITION FOR INTERACTION BETWEEN TRICHLOROETHYLENE AND CHLOROFORM  

EPA Science Inventory

Trichloroethylene (TCE) and chloroform (CHCl3) are two of the most common environmental contaminants found in water. PBPK models have been increasingly used to predict target dose in internal tissues from available environmental exposure concentrations. A closed inhalation (or g...

154

COVALENT BINDING OF TRICHLOROETHYLENE TO PROTEINS IN HUMAN AND RAT HEPATOCYTES. (R826409)  

EPA Science Inventory

The environmental contaminant and occupational solvent trichloroethylene is metabolized to a reactive intermediate that covalently binds to specific hepatic proteins in exposed mice and rats. In order to compare covalent binding between humans and rodents, primary hepatocyte c...

155

ELECTROCHEMICAL DECHLORINATION OF TRICHLOROETHYLENE USING GRANULAR-GRAPHITE ELECTRODES: IDENTIFICATION AND QUANTIFICATION OF DECHLORINATION PRODUCTS  

EPA Science Inventory

Electrochemical degradation (ECD) utilizes high redox potential at the anode and low redox potential at the cathode to oxidize and/or reduce organic and inorganic contaminants. ECD of Trichloroethylene (TCE), although theoretically possible, has not been experimentally proven. Th...

156

Development of Packed-Tower Air Strippers for Trichloroethylene Removal at Wurtsmith Air Force Base, Michigan.  

National Technical Information Service (NTIS)

Packed-tower air stripping was researched and developed to treat trichloroethylene (TCE)-contaminated groundwater at Wurtsmith Air Force Base (Oscoda), Michigan. A leaking underground storage tank has caused a 1000 meters (3200 feet) long, 500 meters (160...

R. L. Gross

1985-01-01

157

Effect of Tetraethyl Thiuram Disulphide (Disulfiram) on Metabolism of Trichloroethylene in Man  

PubMed Central

The amounts of trichloroethanol and trichloroacetic acid excreted in the urine of four subjects who inhaled trichloroethylene in a concentration of about 1 mg./l. for a period of five hours in a laboratory experiment were determined. This experiment was repeated under the same conditions after tetraethyl thiuram disulphide (disulfiram) had been given in divided doses, totalling 3 or 3·5 g. The elimination of trichloroethanol in urine was decreased by 40 to 64%, and of trichloroacetic acid by 72 to 87%. The trichloroethylene excreted by the lungs in two of the subjects increased up to 65% of that retained within five hours. It is concluded that tetraethyl thiuram disulphide (disulfiram) strikingly inhibits the oxidation of trichloroethylene. The possible therapeutic use of this substance in cases of severe peroral trichloroethylene intoxication is discussed.

Bartonicek, V.; Teisinger, J.

1962-01-01

158

EFFECTS OF REACTOR CONDITIONS ON ELECTROCHEMICAL DECHLORINATION OF TRICHLOROETHYLENE USING GRANULAR-GRAPHITE ELECTRODE.  

EPA Science Inventory

Trichloroethylene (TCE) was electrochemically dechlorinated in aqueous environments using granular graphite cathode in a mixed reactor. Effects of pH, current, electrolyte type, and flow rate on TCE dechlorination rate were evaluated. TCE dechlorination rate constant and gas pr...

159

EFFECTS OF REACTION PARAMETERS ON ELECTROCHEMICAL DECHLORINATION OF TRICHLOROETHYLENE RATE AND BY-PRODUCTS  

EPA Science Inventory

Trichloroethylene (TCE) was electrochemically dechlorinated in aqueous environments using granular graphite cathode in a mixed reactor. Effects of pH, current, electrolyte type, and flow rate on TCE dechlorination rate were evaluated. TCE dechlorination rate constant and gas prod...

160

EFFECTS OF REACTOR CONDITIONS ON ELECTROCHEMICAL DECHLORINATION OF TRICHLOROETHYLENE USING GRANULAR-GRAPHITE ELECTRODE  

EPA Science Inventory

Trichloroethylene (TCE) was electrochemically dechlorinated in aqueous environments using granular graphite cathode in a mixed reactor. Effects of pH, current, electrolyte type, and flow rate on TCE dechlorination rate were evaluated. TCE dechlorination rate constant and gas pr...

161

EFFECTS OF TEMPERATURE ON TRICHLOROETHYLENE DESORPTION FROM SILICA GEL AND NATURAL SEDIMENTS. 1. ISOTHERMS. (R822626)  

EPA Science Inventory

Aqueous phase isotherms were calculated from vapor phase desorption isotherms measured at 15, 30, and 60 C for trichloroethylene on a silica gel, an aquifer sediment, a soil, a sand fraction, and a clay and silt fraction, all at...

162

EFFECTS OF TEMPERATURE ON TRICHLOROETHYLENE DESORPTION FROM SILICA GEL AND NATURAL SEDIMENTS. 2. KINETICS. (R822626)  

EPA Science Inventory

Isothermal desorption rates were measured at 15, 30, and 60 C for trichloroethylene (TCE) on a silica gel, an aquifer sediment, a soil, a sand fraction, and a clay and silt fraction, all at 100% relative humidity. Temperature-st...

163

Consideration of the Target Organ Toxicity of Trichloroethylene in Terms of Metabolite Toxicity and Pharmacokinetics.  

National Technical Information Service (NTIS)

Trichloroethylene (TRI) is readily absorbed into the body through the lungs and gastrointestinal mucosa. Exposure to TRI can occur from contamination of air, water, and food; and the contamination may be sufficient to produce adverse effects in the expose...

I. W. F. Davidson R. P. Beliles

1992-01-01

164

Development of a replacement for trichloroethylene in the two-stage cleaning process  

NASA Astrophysics Data System (ADS)

Isopropyl alcohol, d-limonene, and a synthetic mineral spirits were compared for effectiveness as replacements for trichloroethylene in an ultrasonic cleaning process. All were found to be suitable. Isopropyl alcohol is recommended as the replacement.

Harding, W. B.

1992-12-01

165

DEGRADATION OF TRICHLOROETHYLENE UNDER HIGH-TEMPERATURE THERMAL SOURCE-ZONE REMOVAL CONDITIONS (ABSTRACT ONLY)  

EPA Science Inventory

Trichloroethylene (TCE) is a contaminant commonly found in the subsurface at industrial and military installations in the United States. Oxidation of TCE (C2HCl3) to carbon dioxide (CO2) and chloride ions (Cl-) has been reported to occu...

166

Dynamics of toluene degradation in biofilters  

SciTech Connect

Biodegradation processes have been validated as a promising alternative to other conventional air pollution control technologies. The objective of this research was to systematically investigate the transient behavior of shut down and restart-up operation and shock loading of the biofilter. Experiments were conducted in three laboratory-scale biofilters with mixtures of chaff/compost, D.E. (diatomaceous earth)/compost, and GAC (granular activated carbon)/compost, respectively as the filter materials. Toluene was used as the gas pollutant in this study. The response of each biofilter to shock loading was studied by abruptly changing the concentration or flow rate of the inlet gas. For each transient operation, toluene concentration was continuously measured until a new steady state was achieved. The results indicated that the biofilters responded effectively to the shut down and restart-up operation and shock loading of toluene concentration or gas flow rate. Moreover, the highly adsorptive GAC could improve the biofilter performance, especially for the treatment of less water soluble compounds such as toluene. Therefore, the GAC/compost biofilter had the highest maximum elimination capacity of 97 (g hr{sup {minus}1} m{sup {minus}3}). 17 refs., 8 figs.

Tang, Hsiu-Mu; Hwang, Shyh-Jye [National Tsing Hua Univ., Hsin Chu (Taiwan, Province of China); Hwang, Sz-Chwun [ITRI, Hsin Chu (Taiwan, Province of China)

1995-12-31

167

Degradation of trichloroethylene using highly adsorptive allophane–TiO 2 nanocomposite  

Microsoft Academic Search

A highly adsorptive allophane–TiO2 nanocomposite photocatalyst was prepared by dispersing nanoparticles of the natural clay mineral allophane into a titanium alkoxide solution by the sol–gel method. During the photocatalytic degradation of trichloroethylene using the allophane–TiO2 nanocomposite, emission of the intermediate product, phosgene, was drastically inhibited. Trichloroethylene was transformed into the intermediate products, phosgene and dichloroacetyl chloride, on the TiO2 during

Hiromasa Nishikiori; Masaru Furukawa; Tsuneo Fujii

2011-01-01

168

Effect of Trichloroethylene on the Photocatalytic Oxidation of Methanol on TiO 2  

Microsoft Academic Search

During photocatalytic oxidation (PCO), methanol reacts to formaldehyde, some of which desorbs from TiO2 at room temperature. Formaldehyde that remains on the surface oxidizes to adsorbed formate, which dehydrogenates to CO2 in a single step without forming any long-lived intermediates. Adding trichloroethylene (TCE) during PCO of methanol increases the rates of methanol ? formaldehyde and formic acid ? CO2. Trichloroethylene

Darrin S. Muggli; Michael J. Odland; Lucas R. Schmidt

2001-01-01

169

Criteria for a Recommended Standard - Occupational Exposure to Toluene.  

National Technical Information Service (NTIS)

The report provides relevant data concerning the exposure of humans to toluene within the workplace. Recommendations for a toluene standard are provided based on analysis of data. The document covers the workplace environment (Air), medical, labelling (Po...

1973-01-01

170

Project Overview: IRIS TOXICOLOGICAL REVIEW AND SUMMARY DOCUMENTS FOR TOLUENE  

EPA Science Inventory

Toluene is used as an additive to gasoline mixtures (BTEX) to increase octane ratings, in benzene production, and as a solvent in paints, coatings, inks, adhesives, and cleaners. Additionally, toluene is used in the production of nylon, plastics, and polyurethanes. Toluene was o...

171

Apartment residents' and day care workers' exposures to tetrachloroethylene and deficits in visual contrast sensitivity.  

PubMed Central

Tetrachloroethylene (also called perchloroethylene, or perc), a volatile organic compound, has been the predominant solvent used by the dry-cleaning industry for many years. The U.S. Environmental Protection Agency (EPA) classified perc as a hazardous air pollutant because of its potential adverse impact on human health. Several occupational studies have indicated that chronic, airborne perc exposure adversely affects neurobehavioral functions in workers, particularly visual color discrimination and tasks dependent on rapid visual-information processing. A 1995 study by Altmann and colleagues extended these findings, indicating that environmental perc exposure at a mean level of 4,980 microg/m(3) (median=1,360 microg/m(3)) alters neurobehavioral functions in residents living near dry-cleaning facilities. Although the U.S. EPA has not yet set a reference concentration guideline level for environmental exposure to airborne perc, the New York State Department of Health set an air quality guideline of 100 microg/m(3). In the current residential study, we investigated the potential for perc exposure and neurologic effects, using a battery of visual-system function tests, among healthy members of six families living in two apartment buildings in New York City that contained dry-cleaning facilities on the ground floors. In addition, a day care investigation assessed the potential for perc exposure and effects among workers at a day care center located in the same one-story building as a dry-cleaning facility. Results from the residential study showed a mean exposure level of 778 microg/m(3) perc in indoor air for a mean of 5.8 years, and that perc levels in breath, blood, and urine were 1-2 orders of magnitude in excess of background values. Group-mean visual contrast sensitivity (VCS), a measure of the ability to detect visual patterns, was significantly reduced in the 17 exposed study participants relative to unexposed matched-control participants. The groups did not differ in visual acuity, suggesting that the VCS deficit was of neurologic origin. Healthy workers in the day care investigation were chronically exposed to airborne perc at a mean of 2,150 microg/m(3) for a mean of 4.0 years. Again, group-mean VCS, measured 6 weeks after exposure cessation, was significantly reduced in the nine exposed workers relative to matched controls, and the groups did not differ significantly in visual acuity. These results suggested that chronic, environmental exposure to airborne perc adversely affects neurobehavioral function in healthy individuals. Further research is needed to assess the susceptibility of the young and elderly to perc-induced effects, to determine whether persistent solvent-induced VCS deficits are a risk factor for the development of neurologic disease, and to identify the no observable adverse effect level for chronic, environmental, perc exposure in humans.

Schreiber, Judith S; Hudnell, H Kenneth; Geller, Andrew M; House, Dennis E; Aldous, Kenneth M; Force, Michael S; Langguth, Karyn; Prohonic, Elizabeth J; Parker, Jean C

2002-01-01

172

Interfacial Properties of a Hydrophobic Dye in the Tetrachloroethylene-Water-Glass Systems  

SciTech Connect

Interfacial effects play an important role in governing multiphase fluid behavior in porous media. Strongly hydrophobic organic dyes, used in many experimental studies to facilitate visual observation of the phase distributions, have generally been implicitly assumed to have no influence on the interfacial properties of the various phases in porous media. Sudan IV is the most commonly used dye for non-aqueous phase liquids (NAPLs) in laboratory experiments. It has also been used in at least one field experiment. The effects of this dye on the tetrachloroethylene (PCE)-water-glass system were investigated to test the assumption that the dye does not effect the interfacial properties and therefore PCE mobility. The results indicate that the dye does indeed change the interfacial relationships.The effect of the dye on the interfacial relationships is a complex function of the dye concentration, the solid phase composition, and the dynamic rate of new interface formation. The dye caused a slight (<10 percent) increase in interfacial tension at low concentrations (<0.1 g/L) and high rates of new interface formation. The dye reduced interfacial tension between PCE and water at low rates of new interface formation for all dye concentrations tested (0.00508 to 5.08 g/L). At the highest dye concentration, the PCE-water interfacial tension was significantly reduced regardless of the rate of new interface formation. The apparent interfacial tension increase at low dye concentrations is suspected to be an artifact of a low measured IFT value for the undyed PCE caused by leaching of rubber o-rings by the PCE prior to testing in the final drop-volume configuration.In addition to reducing interfacial tension, the dye was found to significantly alter the wetting relationship between PCE and water on a glass surface at and above the range of reported dye concentrations cited in the literature (1.1 to 1.7 g/L). The wetting relationship was rendered neutral from a water-wet initial condition at the highest dye concentration. The contact angle, measured through the aqueous phase, changed from 58 degrees for undyed PCE to 93 degrees at a dye concentration of 5.08 g/L. Complete reversal of the wettability is likely given the short equilibration time used in this study (approximately five minutes) together with literature indications that hundreds to thousands of hours may be required to reach equilibrium during contact angle measurements. Observations suggesting changing wetting relationships were also noted between PCE, water, and the platinum-iridium surface used in the standard du No/374y ring method for measuring interfacial tension.Observations of the dyed-PCE-water interface behavior during du No/374y ring interfacial tension measurements were similar to observations noted previously during measurements of the interfacial tension between the Savannah River Site (SRS) M-Area Settling Basin DNAPL (M-Area DNAPL) and water. This observation suggests that the M-Area DNAPL may contain surface active components. If this proves to be the case, it would have significant implications for how the M-Area DNAPL is distributed and moves in the SRS subsurface.

Tuck, D.M.

1999-02-23

173

Behavior of toluene added to sludge-amended soils  

SciTech Connect

Toluene is a priority pollutant that can be introduced to soils in a variety of wastes, including some municipal sludges. Laboratory experiments were conducted to study the behavior of toluene in two soils in the presence and absence of municipal sludge. Sludge additions increased toluene adsorption in two soils because of increased organic C content. The source of organic C (soil or sludge) and soil clay content also influenced toluene adsorption. Toluene adsorption-desorption was reversible in one soil, but slightly hysteretic in the other soil. An air-flow incubation system was used to evaluate toluene volatilization and degradation. The primary fate of surface-applied toluene in both soils was volatilization. Toluene volatilization rates were independent of sludge treatments. Toluene degradation was negligible in all treatments because of rapid volatilization losses. Despite increased toluene adsorption in the presence of sludge and reduced volatilization in saturated soils, gaseous transfer dominated all soils and treatments so that no toluene remained after 10 d.

Jin, Y.; O'Connor, G.A.

1990-01-01

174

Physiologically-based pharmacokinetic (PBPK) modeling of two binary mixtures: metabolic activation of carbon tetrachloride by trichloroethylene and metabolic inhibition of chloroform by trichloroethylene.  

EPA Science Inventory

The interaction between trichloroethylene (TCE) and chloroform (CHCI3) has been described as less than additive, with co-exposure to TCE and CHC13 resulting in less hepatic and renal toxicity than observed with CHCl3 alone. In contrast, the nonadditive interaction between TCE and...

175

Biotransformation of trichloroethylene by a phenol-induced mixed culture  

SciTech Connect

Biodegradation of trichloroethylene (TCE) was studied using a mixed culture of aerobic, phenol-induced organisms. Abiotic experiments showed that sorption of TCE to biomass was negligible in the systems studied. The effects of influent phenol and TCE concentration on the TCE degradation capacity of the culture were studied using chemostats. A relationship exists between the influent phenol/TCE ratio and TCE biodegradation. TCE transformation yields ranged from 0.052 to 0.222 mg TCE removed/mg phenol removed. Monod kinetic coefficients for phenol degradation were determined. Monod kinetic coefficients were also determined for TCE biotransformation by resting cells. The concept of transformation capacity was used to model the decrease in active biomass concentration caused by TCE transformation. In mineralization studies using {sup 14}C-labeled TCE, 22% of the degraded mass of TCE was transformed to carbon dioxide, 8.8% was incorporated into biomass, 42% was transformed to nonvolatile products, with the remaining, unrecovered 27% most likely transformed into volatile or semivolatile products.

Shurtliff, M.M. [CH2M Hill, Gainesville, FL (United States); Parkin, G.F.; Gibson, D.T. [Univ. of Iowa, Iowa City, IA (United States); Weathers, L.J. [Univ. of Maine, Orono, ME (United States). Dept. of Civil and Environmental Engineering

1996-07-01

176

Complete dissolution of trichloroethylene in saturated porous media  

SciTech Connect

Porous media containing trichloroethylene (TCE) trapped at residual saturation in otherwise water-saturated porous media were flushed with water to asses the dissolution rate of TCE as TCE volumetric fractions approached zero. Careful attention to column design and experimental methods limited the effect of column materials on effluent concentrations. Effluent concentration measurements during TCE dissolution are presented for a glass bead porous medium, a mixed sand, and a treated soil. Effluent concentrations were measured as they decreased below 5 {micro}g/L, the maximum allowable contaminant level, in the glass bead and mixed sand media. Effluent concentrations from columns packed with treated soil were measured down to 20 {micro}g/L. Solvent extraction of the treated soil after the dissolution experiments revealed that extremely small quantities of TCE were retained in this medium. Results from parallel experiments on columns exposed to only aqueous TCE suggest that TCE remaining in the treated soil columns was sorbed to the porous medium. Existing power-law models were capable of describing TCE dissolution in these media, if the exponent on the TCE volume fraction was modified appropriately.

Imhoff, P.T. [Univ. of Delaware, Newark, DE (United States). Dept. of Civil and Environmental Engineering; Arthur, M.H.; Miller, C.T. [Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Environmental Sciences and Engineering

1998-08-15

177

Plasma remediation of gas streams contaminated by trichloroethylene  

SciTech Connect

There is increasing interest in using plasmas to cleanse gas streams of toxic gases and for toxic waste remediation. Silent discharges (or dielectric barrier discharges) are attractive in this regard because they operate stably at high power deposition and atmospheric pressure. The authors have experimentally and computationally investigated the removal of trichloroethylene (C{sub 2}HCl{sub 3}) or TCE from Ar/O{sub 2}/H{sub 2}O gas streams using a silent discharge. Experimental results will be discussed where TCE is removed from the gas stream (1000 ppm reduced to < 1 ppm) with moderate energy deposition (10s mJ-cm{sup {minus}3}). The desired reaction products are CO{sub 2} and UC1. The plasma removal of TCE, however, directly produces undesirable products such as CHOCl and COCl{sub 2} (phosgene). These products can also be oxidized and removed from the gas stream by further increasing power deposition beyond that required for removal of TCE. Reaction mechanisms will be discussed with results from a plasma chemistry computer model.

Evans, D.; Kushner, M.K. [Univ. of Illinois, Urbana, IL (United States); Rosocha, L.A. [Los Alamos National Lab., NM (United States)

1992-12-01

178

Trichloroethylene exposure. Biological monitoring by breath and urine analyses.  

PubMed Central

A mathematical model developed previously has been used to study some aspects of biological monitoring of exposure to trichloroethylene (TRI) by the analysis of this solvent in alveolar air or of its metabolites, trichloroethanol (TCE) and trichloroacetic acid (TCA), in urine. Assuming that a biological control must be representative of the time-weighted average concentration (TWA), it was found that sampling for TRI and TCE analyses must be carried out the morning after the exposure being considered. On the other hand, for a TCA analysis, the timing of urine sampling is not a determinant factor. Theortical limit concentrations have been set up for these biological indicators, but it is shown that their application must be restricted to exposures which are quantitatively reproducible from one day to the next. In all other cases, it appears that this monitoring method can lead to errors in the estimated exposure concentrations. A tentative method of biological monitoring is therefore proposed. It is based on the analysis of TCE in the urine or TRI in the alveolar air before and after the exposure being monitored. TCA is not considered to be sensitive enough to variations in the inspired concentration to be used as an indicator of a single exposure risk.

Droz, P O; Fernandez, J G

1978-01-01

179

Pharmacokinetic modeling of trichloroethylene and trichloroacetic acid in humans  

SciTech Connect

The development and application of appropriate physiologically based pharmaocokinetic (PBPK) models of chemical contaminants will provide a rational basis for risk assessment extrapolation. Trichloroethylene (TCE) is a widespread contaminant found in soil, groundwater, and the atmosphere. Exposures to TCE and its metabolities have been found to be carcinogenic in rodents. In this study, a PBPK model for TCE and its major metabolite, trichloracetic acid (TCA), is developed for humans. The model parameters, estimated from the relevant published literature on human exposures to TCE and its metabolites, are described. Key parameters describing the metabolism of TCE and the kinetics of TCA were estimated by optimization. The optimization was accomplished by simultaneously matching model predictions to observations of TCE concentrations in blood and exhaled breath, TCA plasma concentrations, and urinary TCA excretin from five published studies. The optimized human PBPK model provides an excellent description of TCE and TCA kinetics. The predictions were especially good for TCA plasma concentrations following repeated TCE inhalation, an exposure scenario similar to that occurring in the workplace. The human PBPK model can be used to estimate dose metrics resulting from TCE exposures and is therefore useful when considering the estimation of human health risks associated with such exposures.

Allen, B.C. (Clement International Corp. Ruston, LA (United States)); Fisher, J.W. (Armstrong Lab, Wright-Patterson AFB, OH (United States))

1993-02-01

180

Physiological pharmacokinetic modeling of inhaled trichloroethylene in rats  

SciTech Connect

The pharmacokinetics of trichloroethylene (TCE) was characterized during and following inhalation exposures of male Sprague-Dawley rats. The blood and exhaled breath TCE time-course data were used to formulate and assess the accuracy of predictions of a physiologically based pharmacokinetic (PB-PK) model for TCE inhalation. Fifty or 500 ppm TCE was inhaled by unanesthetized rates of 325-375g for 2 hrs through a miniaturized one-way breathing valve. Repetitive samples of the inhaled and exhaled breath streams, as well as arterial blood, were collected concurrently during and for 3 hrs following the exposures and analyzed fo TCE by headspace gas chromatography. Respiratory rates and volumes were continuously monitored and used in conjunction with the pharmacokinetic data to delineate uptake and elimination profiles. Levels of TCE in the exhaled breath attained near steady-state soon after the beginning of exposures, and were then directly proportional to the inhaled concentration. Exhaled breath levels of TCE in rats were similar in magnitude to values previously published for TCE inhalation exposures of humans. The uptake and elimination profiles were accurately simulated by the PB-PK model for both the 50 and 500 ppm TCE exposure levels. Such a model may be quite useful in risk assessments in predicting internal (i.e., systemically absorbed) doses of TCE and other volatile organics under a variety of exposure scenarios.

Dallas, C.E.; Gallo, J.M.; Ramanathan, R.; Muralidhara, S.; Bruckner, J.V.

1991-01-01

181

Mass recovery methods for trichloroethylene in plant tissue.  

SciTech Connect

Monitoring expenses form a significant fraction of the costs associated with remediation of contaminated soil and groundwater sites. A novel monitoring method that could result in significant cost savings is the use of plants as monitoring devices; previous work indicates that plant tissue samples, especially trunk (core) and branch samples, can be used to delineate soil and groundwater plumes at phytoremediation sites. An important factor in reducing the uncertainty associated with this sampling method is development of a technique to analyze, both consistently and accurately, the chemicals stored in plant tissue samples. The present research presents a simple, robust, and inexpensive technique to recover most of the contaminant in plant branch tissue, irrespective of the age or species of the plant. Trichloroethylene (TCE) was the chemical analyzed. A number of headspace and solvent extraction techniques in the literature were evaluated, including headspace extraction at different incubation times and temperatures and solvent extraction using hexane or hot methanol. Extraction using hot methanol was relatively fast, simple, and reliable; this method recovered more than 89% of the TCE present in branches of five different tree species.

Gopalakrishnan, G.; Negri, M. C.; Werth, C. J.; Energy Systems; Univ. of Illionis

2009-06-01

182

Cometabolic degradation of trichloroethylene in a bubble column bioscrubber  

SciTech Connect

A bubble column bioreactor was used as bioscrubber to carry out a feasibility study for the cometabolic degradation of trichloroethylene (TCE). Phenol was used as cosubstrate and inducer. The bioreactor was operated like a conventional chemostat with regard to the cosubstrate and low dilution rates were used to minimize the liquid outflow. TCE degradation measurements were carried out using superficial gas velocities between 0.47 and 4.07 cm s{sup {minus}1} and TCE gas phase loads between 0.07 and 0.40 mg L{sup {minus}1}. Depending on the superficial gas velocity used, degrees of conversion between 30% and 80% were obtained. A simplified reactor model using plug flow for the gas phase, mixed flow for the liquid phase, and pseudo first order reaction kinetics for the conversion of TCE was established. The model is able to give a reasonable approximation of the experimental data. TCE degradation at the used experimental conditions is mainly limited by reaction rate rather than by mass transfer rate. The model can be used to calculate the reactor value and the biomass concentration for a required conversion.

Hecht, V.; Brebbermann, D.; Bremer, P.; Deckwer, W.D. [Bereich Bioverfahrenstechnik, Braunschweig (Germany). Gesellschaft fuer Biotechnologische Forschung mbH

1995-08-20

183

Destruction of pollutants in water with ozone in combination with ultraviolet radiation. 1. General principles and oxidation of tetrachloroethylene  

SciTech Connect

Oxidation of organic micropollutants in water is significantly faster with ozone in combination with ultraviolet radiation than one would predict on the basis of the individual processes involved. A formalism for the analysis of O/sub 3//UV kinetics is presented in which substrate decay is represented as a linear combination of terms representing purging, ozonation, photolysis, and photolytic ozonation (O/sub 3//UV). For the substrate tetrachloroethylene (TCE) the process is overall first order in TCE. With a continuously sparged stirred tank reactor, times for the elimination of 63% of the substrate (T/sub 1/) have values of 100, 26, 20, and 7 min for purging, ozonation only, photolysis only, and photolytic ozonation, respectively. Significant retardation of O/sub 3//UV kinetics is observed in a lake-water matrix as opposed to purified water, possible due to a radical intermediate involved in the O/sub 3//UV process.

Peyton, G.R.; Huang, F.Y.; Burleson, J.L.; Glaze, W.H.

1982-08-01

184

Identification and removal of trichloroethylene contamination: A case study at Wright-Patterson Air Force Base. Master's thesis  

Microsoft Academic Search

The purpose of this thesis was to determine the parameters associated with installing monitoring wells to detect trichloroethylene contamination, and to determine what emphasis or weights were placed on the nine National Contingency Plan criteria to select a treatment method that would remove trichloroethylene. The results of this study should help installation restoration project officers understand what parameters should be

Butterfield

1991-01-01

185

Propane-induced biodegradation of vapor phase trichloroethylene  

SciTech Connect

Microbial degradation of trichloroethylene (TCE) has been demonstrated under aerobic conditions with propane. The primary objective of this research was to evaluate the feasibility of introducing a vapor phase form of TCE in the presence of propane to batch bioreactors containing a liquid phase suspension of Mycobacterium vaccae JOB5 to accomplish degradation. The reactor system consisted of three phases: a vapor phase introducing air, propane, and a solid phase in the form of the microorganisms. Long-term and initial rate experiments were conducted on three culture sets to evaluate microbial response. In two long-term tests fed propane and approximately 0.1 mg/L and 1 mg/L of TCE, respectively, propane utilization was more efficient at the high TCE concentration because the propane degradation rate was approximately the same for both tests. In addition, TCE utilization decreased after complete propane consumption. Initial rate tests on culture sets fed propane only revealed that cells with a history of exposure to a high concentration of TCE had the highest specific growth rate, but the lowest half-saturation constant. Tests fed variable TCE concentration (0.031 to 5.378 mg/L in the liquid phase) with no propane showed TCE depletion but no biomass growth. The tests revealed that the TCE removal increased as the TCE concentration increased, indicating a greater removal efficiency at the higher concentrations. Tests with a constant initial propane concentration and variable liquid phase TCE concentration revealed that specific propane utilization was essentially the same.

Wilcox, D.W. [John Carollo Engineers, College Station, TX (United States); Autenrieth, R.L.; Bonner, J.S. [Texas A and M Univ., College Station, TX (United States). Dept. of Civil Engineering

1995-05-20

186

Trichloroethylene Does Not Accelerate Autoimmune Diabetes in NOD Mice.  

PubMed

Pre-existing or contributing risk factors, including genetic predisposition and environmental influences, are largely thought to play a crucial (though ill-elucidated) role in the development of autoimmunity. Trichloroethylene (TCE) is a widely used organic solvent, which has been suspected of increasing the prevalence of autoimmune diseases, e.g., lupus, following environmental contamination. Although few epidemiological data are available, several studies reported an accelerated and more severe disease in TCE-exposed autoimmunity-prone MRL(+/+) mice. To test whether TCE can exert similar deleterious effects on organ-specific autoimmune diseases, non obese diabetic (NOD) mice were given 5 mg/ml TCE via the drinking water for 12 weeks. TCE administration induced a decrease in CD44(+) splenic T-cells and CD45RB(high), CD54(+) blood and splenic T-cells. Conversely, the number of CD45RB(low) splenocytes was increased. Interestingly, the progressive increase in serum TNF-alpha and IFN-gamma levels normally seen with age in these mice was inhibited by TCE. There was also a relative lower incidence of histological changes in the pancreas of TCE-exposed NOD mice than in unexposed mice. Contrary to what has been found in systemic models of autoimmunity, TCE did not accelerate the diabetes of NOD mice and may have a protective effect. This finding suggests that comparative studies using different genetically related autoimmune-prone models are needed to investigate the role of xenobiotics in the precipitation of autoimmunity, particularly in sensitive populations. PMID:18958647

Ravel, Guillaume; Christ, Marielle; Perron-Lepage, Marie-France; Condevaux, Fabienne; Descotes, Jacques

2005-07-01

187

Conditions affecting the mutagenicity of trichloroethylene in Salmonella  

SciTech Connect

Trichloroethylene (TCE) is a high production volume chemical frequency stabilized with oxiranes. These oxiranes may be responsible for the mutagenic activity of TCE in Salmonella, which has been occasionally, but not consistently, reported. High purity and oxirane-stabilized TCE samples were tested for their mutagenic potential in Salmonella typhimurium strains TA 1535, TA 98, and TA 100. Stabilized TCE was tested using a preincubation protocol up to a dose level of 10,000 {mu}g per plate, but not mutagenic response was observed in either the presence or absence of a supplementary metabolic activation system (S9 mix) derived from Aroclor 1254-induced male rat liver. TCE without oxirane stabilizers also was nonmutagenic when tested in a vapor delivery system at nominal concentrations of up to 20% and using S9 mix derived from either rat or hamster. TCE containing 0.5-0.6% 1,2-epoxybutane did induce mutagenic responses from strains TA 1535 and TA 100 in the presence and absence of S9 mix. Vapor-phase tests with 1,2-epoxybutane showed that an atmospheric concentration of 0.009% could induce 12-fold and 3-fold increases, respectively, in strains TA 1535 and TA 100. These increases would account for the mutagenic activity of the stabilized TCE sample. The absence of a significant response caused by unstabilized TCE in the presence of S9 mix is probably due to a lack of assay sensitivity, since chloral, a metabolite of TCE, is a mutagen in TA 100.

McGregor, D.B.; Reynolds, D.M. (Inveresk Research International, Musselburg (England)); Zeiger, E. (National Institute of Environmental Health Sciences, Research Triangle Park, NC (USA))

1989-01-01

188

Inhalation studies of the genotoxicity of trichloroethylene to rodents.  

PubMed

Trichloroethylene (TCE) (CAS No. 79-01-6) is an industrial solvent used in degreasing, dry cleaning, and numerous other medical and industrial processes. Controlled inhalation studies were performed using male C57BL/6 mice and CD rats to determine if TCE can induce cytogenetic damage in vivo. Animals were exposed in groups of five to target concentrations of either 0, 5, 500, or 5000 ppm TCE for 6 h. Tissue samples were taken between 18 and 19 h post exposure. Peripheral blood lymphocytes (PBLs) in rats and splenocytes in mice were cultured and analyzed for the induction of sister-chromatid exchanges, chromosome aberrations, and micronuclei (MN) in cytochalasin B-blocked binucleated cells. Bone marrow polychromatic erythrocytes (PCEs) were analyzed for MN. The only positive response observed was for MN in rat bone marrow PCEs. TCE caused a statistically significant increase in MN at all concentrations, inducing an approximate fourfold increase over control levels at 5000 ppm. TCE was also cytotoxic in rats, causing a significant concentration-related decrease in the ratio of PCEs/normochromatic erythrocytes. This study indicates that there may be species-specific cytogenetic effects attributed to TCE inhalation exposure. In follow-up studies, CD rats were exposed for 6 h/day over 4 consecutive days to either 0, 5, 50 or 500 ppm TCE. No statistically significant concentration-related increases in cytogenetic damage were observed. While the MN frequencies in the 4-day study were comparable to those at the equivalent concentrations in the 1-day study, they were not significantly elevated due to an unusually high MN frequency in the controls. A subsequent replication of the 1-day 5000 ppm TCE exposure with rats again showed a highly significant increase in MN frequencies compared to concurrent controls. PMID:7519326

Kligerman, A D; Bryant, M F; Doerr, C L; Erexson, G L; Evansky, P A; Kwanyuen, P; McGee, J K

1994-08-01

189

Impact of iron sulfide transformation on trichloroethylene degradation  

SciTech Connect

Trichloroethylene (TCE) is one of the most common and persistent groundwater contaminants encountered at hazardous waste sites around the world. A growing body of evidence indicates that iron sulfides play an important role in degrading TCE in natural environments and in engineered systems designed for groundwater cleanup. In this study, we investigate transformation processes of iron sulfides and consequent impacts on TCE degradation using batch experimental techniques, transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). Our results show that mackinawite is highly reactive toward TCE and no detectable mineralogical changes were detected during the course of reaction. However, freeze-dried FeS transformed to a mixture of mackinawite and greigite during the freeze drying process, with further mineralogical changes during reaction with TCE to lepidocrocite, goethite and pyrite. Newly formed lepidocrocite is a transient phase, with conversion to goethite over time. TCE transformation kinetics show that freeze-dried FeS is 20-50 times less reactive in degrading TCE than non-freeze-dried FeS, and the TCE degradation rate increases with pH (from 5.4 to 8.3), possibly due to an increase of surface deprotonation or electron transfer at higher pH. Results suggest that freeze drying could cause FeS particle aggregation, decreased surface area and availability of reactive sites; it also could change FeS mineralogy and accelerate mineral transformation. These aspects could contribute to the lower reactivity of freeze-dried FeS toward TCE degradation. Modeling results show that FeS transformation in natural environments depends on specific biogeochemical conditions, and natural FeS transformation may affect mineral reactivity in a similar way as compared to the freeze drying process. Rapid transformation of FeS to FeS{sub 2} could significantly slow down TCE degradation in both natural and engineered systems.

He, Y. Thomas; Wilson, John T.; Wilkin, Richard T. (EPA)

2010-05-04

190

In-situ chemical oxidation of trichloroethylene using hydrogen peroxide  

SciTech Connect

Laboratory studies were conducted to determine the feasibility of injection and mixing hydrogen peroxide (H{sub 2}O{sub 2}) solutions into clay soils contaminated with trichloroethylene (TCE) to achieve in-situ chemical oxidation. Bench-scale slurry studies were conducted first using 0.3 L slurry reactors and TCE concentrations in the 1.9 to 34 mg/kg range. TCE reductions as high as 98% of the initial concentration were achieved with a H{sub 2}O{sub 2} dose of 28 g H{sub 2}O{sub 2}/kg soil. TCE degradation increased with increasing hydrogen peroxide strength and appeared independent of the initial TCE concentration. Column studies were conducted with an apparatus fabricated to simulate in-situ mixing and chemical oxidant injection. Stainless steel columns 20 cm in diameter and 23 cm long, which were packed with clay soil, were mixed with an auger blade while H{sub 2}O{sub 2} solutions were injected through orifices at the back of the mixing blade. The H{sub 2}O{sub 2} doses for the column studies were 1.2 and 2.5 g H{sub 2}O{sub 2}/kg soil, based on an injection concentration of 5% weight H{sub 2}O{sub 2} at volumetric additions of 5% and 10% of the soil volume treated. TCE reductions of 88% and 75% were achieved at the two dosing rates. Based on the results of these laboratory studies, in-situ chemical oxidation of contaminated soils appears to be a viable soil remediation technique that is dependent on the efficient delivery and distribution of H{sub 2}O{sub 2} throughout the region to be treated.

Gates, D.D.; Siegrist, R.L. [Oak Ridge National Lab., TN (United States). Environmental Science Division

1995-09-01

191

Natural attenuation of trichloroethylene in fractured shale bedrock.  

PubMed

This paper describes one of the first well-documented field examples of natural attenuation of trichloroethylene (TCE) in groundwater in a fractured shale bedrock. The study was carried out adjacent to a former waste burial site in Waste Area Grouping 5 (WAG5) on the Oak Ridge Reservation, Oak Ridge, TN. A contaminant plume containing TCE and its daughter products were detected downgradient from the buried waste pits, with most of the contamination occurring in the upper 6 m of the bedrock. The monitoring well array consists of a 35-m-long transect of multilevel sampling wells, situated along a line between the waste pits and a seep which discharges into a small stream. Concentrations of volatile organic carbons (VOCs) were highest in the waste trenches and decreased with distance downgradient towards the seep. Sampling wells indicated the presence of overlapping plumes of TCE, cis-dichloroethylene (cDCE), vinyl chloride (VC), ethylene, ethane, and methane, with the daughter products extending further downgradient than the parent (TCE). This type of distribution suggests anaerobic biodegradation. Measurements of redox potential at the site indicated that iron-reduction, sulfate reduction, and potentially methanogensis were occurring and are conducive to dechlorination of TCE. Bacteria enrichment of groundwater samples revealed the presence of methanotrophs, methanogens, iron-reducing bacteria and sulfate-reducing bacteria, all of which have previously been implicated in anaerobic biodegradation of TCE. 16S rDNA sequence from DNA extracted from two wells were similar to sequences of organisms previously implicated in the anaerobic biodegradation of chlorinated solvents. The combined data strongly suggest that anaerobic biodegradation of the highly chlorinated compounds is occurring. Aerobic biodegradation may also be occurring in oxygenated zones, including near a seep where groundwater exits the site, or in the upper bedrock during seasonal fluctuations in water table elevation and oxygen levels. PMID:12814878

Lenczewski, M; Jardine, P; McKay, L; Layton, A

2003-07-01

192

Permeation of polymeric materials by toluene  

SciTech Connect

The permeation of toluene through protective clothing materials composed of butyl, butyl-coated nomex, neoprene, and polyvinyl alcohol was tested at 25/sup 0/C and 45/sup 0/C with the use of ASTM method F-739. Butyl exhibited breakthrough of 18 min at 25/sup 0/C and 11 min at 45/sup 0/ C. Butyl nomex exhibited breakthrough times of 11 min and 25/sup 0/C and 6 min at 45/sup 0/C. PVA showed no breakthrough in 20 hr. The steady-state permeation rates and the diffusion coefficients were determined.

Vahdat, N.

1987-02-01

193

Electronic and Photoelectron Spectroscopy of Toluene  

NASA Astrophysics Data System (ADS)

Electronic and photoelectron spectra of toluene are presented and discussed. The utilization of a recently reported scheme for assigning the normal vibrations of substituted benzenes allows these spectra to be compared to those of other molecules with unprecedented clarity. Changes in vibrational activity within a series of substituted benzene molecules will be discussed, specifically the increased rate of intramolecular vibrational energy redistribution observed in molecules where the substituent is a methyl group. A. M. Gardner and T. G. Wright, J. Chem. Phys., 135, 114305 (2011)

Gardner, Adrian M.; Green, Alistair M.; Tame-Reyes, Victor; Wright, Timothy G.

2012-06-01

194

Fermentative toluene degradation in anaerobic defined syntrophic cocultures  

Microsoft Academic Search

A syntrophic coculture of a new sulfate-reducing isolate, strain TRM1, with Wolinella succinogenes degraded toluene with either fumarate or NO3? as the terminal electron acceptor. Neither strain TRM1 nor W. succinogenes could metabolise toluene under these conditions in pure culture. Syntrophic degradation was 2–3 times slower than toluene utilisation by strain TRM1 in pure culture with sulfate as electron acceptor.

Rainer U Meckenstock

1999-01-01

195

Stable isotope (C, Cl, and H) fractionation during vaporization of trichloroethylene  

Microsoft Academic Search

Stable isotope fractionation during vaporization of trichloroethylene has been measured, with possible application as a technique to investigate subsurface behavior. The equilibrium value of ι³C{sub vapor-liquid} has been measured between 5 and 35 C, and ι³C{sub vapor-liquid}, γ⁷Cl{sub vapor-liquid}, and ÎD{sub vapor-liquid} have been measured during progressive evaporation of liquid trichloroethylene at 22 {+-} 2 C. Equilibrium values of ι³C{sub

Simon R. Poulson; James I. Drever

1999-01-01

196

Transformation of toluene and benzene by mixed methanogenic cultures.  

PubMed Central

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.

Grbic-Galic, D; Vogel, T M

1987-01-01

197

Cascade regulation of the toluene-3-monooxygenase operon (tbuA1UBVA2C) of Burkholderia pickettii PKO1: role of the tbuA1 promoter (PtbuA1) in the expression of its cognate activator, TbuT.  

PubMed Central

Burkholderia pickettii PKO1 metabolizes toluene and benzene via a chromosomally encoded toluene-3-monooxygenase pathway. Expression of the toluene-3-monooxygenase operon (tbuA1UBVA2C) is activated by the regulator, TbuT, in the presence of toluene. We have identified the TbuT coding region downstream of the toluene-3-monooxygenase structural genes by nucleotide sequence analysis and have shown that although TbuT is similar to XylR and DmpR, two members of the NtrC family of transcriptional activators which control toluene-xylene and (methyl)phenol catabolism, respectively, it is significantly different in the domain associated with effector specificity. Using a tbuA1-lacZ fusion reporter system, we determined that TbuT is activated not only by aromatic effectors but also the chlorinated aliphatic hydrocarbon trichloroethylene. Expression of tbuT and that of the tbuA1UBVA2C operon were found to be linked by readthrough transcription of tbuT from the toluene-3-monooxygenase promoter. As a result, transcription of tbuT is low when the toluene-3-monooxygenase operon is uninduced and high when expression of tbuA1UBVA2C is induced by toluene. Thus, the toluene-3-monooxygenase promoter drives the cascade expression of both the toluene-3-monooxygenase operon and tbuT, resulting in a positive feedback circuit. Examination of the nucleotide sequence upstream of the toluene-3-monooxygenase operon for promoter-like sequences revealed a -24 TGGC, -12 TTGC sequence, characteristic of sigma54 (rpoN)-dependent promoters. Primer extension and tbuA1-lacZ fusion analyses demonstrated that this -24, -12 promoter sequence, referred to as PtbuA1, was the toluene-3-monooxygenase promoter. Upstream of PtbuA1, a DNA region with dyad symmetry exhibited homology with the XylR-binding site present upstream of the Pu promoter. Deletions within this DNA sequence resulted in complete loss of expression from PtbuA1, suggesting that this region may serve as the TbuT-binding site.

Byrne, A M; Olsen, R H

1996-01-01

198

Behavioral toxicology of carbon disulfide and toluene.  

PubMed Central

Organic solvents are pervasive in the communal and industrial environments. Although many are potent central nervous system agents, clearly delineated behavioral effects have played only a minor role in the formation of exposure standards. A comprehensive behavioral pharmacology and toxicology of these compounds is one aim of US/USSR collaboration. The current report describes some actions of carbon disulfide and toulene. Earlier data about the actions of carbon disulfide on pigeon operant performance indicated disruption of schedule-controlled key-pecking. Primate data are now described from a situation designed to determine aversive thresholds to electrical stimulation. Effective concentrations of carbon disulfide produced both a rise in the amount of electric shock tolerated and a diminution of the response force exerted by the monkeys. In experiments with toluene, pigeons were shown to elevate key-pecking rate in an operant situation at certain concentrations. Toluene also was studied for its capacity to maintain self-administration in the same way as drugs of abuse. Monkeys worked to gain access to toulene vapor just as they work for opiates or amphetamines. The current experiments demonstrate how comprehensive the range of behavioral toxicology needs to be to deal with environmental health issues. Images FIGURE 3. FIGURE 5.

Weiss, B; Wood, R W; Macys, D A

1979-01-01

199

Cinnarizinium bis-(p-toluene-sulfonate) dihydrate  

PubMed Central

The asymmetric unit of the title salt [systematic name: 1-benzhydryl-4-cinnamylpiperazine-1,4-diium bis­(p-toluene­sulfonate) dihydrate], C26H30N2 2+·2C7H7O3S?·2H2O, consists of a diprotonated cinnarizinium cation hydrogen bonded through two water mol­ecules to two independent p-toluene­sulfonate anions, one which is disordered over two sets of sites in a 0.793?(3):0.207?(3) ratio. In the cation, the piperazine ring adopts a chair configuration and contains two positively charged N atoms with quarternery character. The dihedral angle between the two benzene rings in the benzhydr­yl group is 71.8?(1)°. The benzene ring flanked opposite the piperazine ring is twisted by 75.9?(9) and 8.8?(3)° from these two benzene rings. In the crystal, the [N—H?Owater—H?O( S)]2 hydrogen-bonded asymmetric unit is connected by further O—H?O hydrogen bonds linking the components into chains along [100].

Kavitha, C. N.; Butcher, Ray J.; Jasinski, Jerry P.; Yathirajan, H. S.; Dayananda, A. S.

2013-01-01

200

Benzene\\/toluene\\/ p -xylene degradation. Part I. Solvent selection and toluene degradation in a two-phase partitioning bioreactor  

Microsoft Academic Search

A two-phase organic\\/aqueous reactor configuration was developed for use in the biodegradation of benzene, toluene and p-xylene, and tested with toluene. An immiscible organic phase was systematically selected on the basis of predicted and experimentally\\u000a determined properties, such as high boiling points, low solubilities in the aqueous phase, good phase stability, biocompatibility,\\u000a and good predicted partition coefficients for benzene, toluene

L. D. Collins; A. J. Daugulis

1999-01-01

201

Copper Enhanced Monooxygenase Activity and FT-IR Spectroscopic Characterisation of Biotransformation Products in Trichloroethylene Degrading Bacterium: Stenotrophomonas maltophilia PM102  

PubMed Central

Stenotrophomonas maltophilia PM102 (NCBI GenBank Acc. no. JQ797560) is capable of growth on trichloroethylene as the sole carbon source. In this paper, we report the purification and characterisation of oxygenase present in the PM102 isolate. Enzyme activity was found to be induced 10.3-fold in presence of 0.7?mM copper with a further increment to 14.96-fold in presence of 0.05?mM NADH. Optimum temperature for oxygenase activity was recorded at 36°C. The reported enzyme was found to have enhanced activity at pH 5 and pH 8, indicating presence of two isoforms. Maximum activity was seen on incubation with benzene compared to other substrates like TCE, chloroform, toluene, hexane, and petroleum benzene. Km and Vmax for benzene were 3.8?mM and 340?U/mg/min and those for TCE were 2.1?mM and 170?U/mg/min. The crude enzyme was partially purified by ammonium sulphate precipitation followed by dialysis. Zymogram analysis revealed two isoforms in the 70% purified enzyme fraction. The activity stain was more prominent when the native gel was incubated in benzene as substrate in comparison to TCE. Crude enzyme and purified enzyme fractions were assayed for TCE degradation by the Fujiwara test. TCE biotransformation products were analysed by FT-IR spectroscopy.

Mukherjee, Piyali; Roy, Pranab

2013-01-01

202

Use of starvation promoters to limit growth and selectively enrich expression of trichloroethylene- and phenol-transforming activity in recombinant Escherichia coli [corrected  

PubMed Central

The expression of much useful bacterial activity is facilitated by rapid growth. This coupling can create problems in bacterial fermentations and in situ bioremediation. In the latter process, for example, it necessitates addition of large amounts of nutrients to contaminated environments, such as aquifers. This approach, termed biostimulation, can be technically difficult. Moreover, the resulting in situ bacterial biomass production can have undesirable consequences. In an attempt to minimize coupling between expression of biodegradative activity and growth, we used Escherichia coli starvation promoters to control toluene monooxygenase synthesis. This enzyme complex can degrade the environmental contaminants trichloroethylene (TCE) and phenol. Totally starving cell suspensions of such strains degraded phenol and TCE. Furthermore, rapid conversions occurred in the postexponential batch or very slow growth (dilution) rate chemostat cultures, and the nutrient demand and biomass formation for transforming a given amount of TCE or phenol were reduced by 60 to 90%. Strong starvation promoters have recently been clones and characterized in environmentally relevant bacteria like Pseudomonas species; thus, starvation promoter-driven degradative systems can now be constructed in such bacteria and tested for in situ efficacy.

Matin, A; Little, C D; Fraley, C D; Keyhan, M

1995-01-01

203

Trichloroethylene cometabolic degradation by Rhodococcus sp. L4 induced with plant essential oils  

Microsoft Academic Search

Cometabolic degradation of TCE by toluene-degrading bacteria has the potential for being a cost-effective bioremediation technology.\\u000a However, the application of toluene may pose environmental problems. In this study, several plant essential oils and their\\u000a components were examined as alternative inducer for TCE cometabolic degradation in a toluene-degrading bacterium, Rhodococcus sp. L4. Using the initial TCE concentration of 80 ?M, lemon and

Oramas Suttinun; Rudolf Müller; Ekawan Luepromchai

2009-01-01

204

Dioxinlike properties of a trichloroethylene combustion-generated aerosol.  

PubMed

Conventional chemical analyses of incineration by-products identify compounds of known toxicity but often fail to indicate the presence of other chemicals that may pose health risks. In a previous report, extracts from soot aerosols formed during incomplete combustion of trichloroethylene (TCE) and pyrolysis of plastics exhibited a dioxinlike response when subjected to a keratinocyte assay. To verify this dioxinlike effect, the complete extract, its polar and nonpolar fractions, some containing primarily halogenated aromatic hydrocarbons, were evaluated for toxicity using an embryo assay, for antiestrogenicity using primary liver cell cultures, and for the ability to transform the aryl hydrocarbon receptor into its DNA binding form using liver cytosol in a gel retardation assay. Each of these assays detect dioxinlike effects. Medaka (Oryzias latipes) embryos and primary liver cell cultures of rainbow trout (Oncorhynchus mykiss) were exposed to concentrations of extract ranging from 0.05 to 45 micrograms/l. Cardiotoxicity with pericardial, yolk sac, and adjacent peritoneal edema occurred after exposure of embryos to concentrations of 7 micrograms/l or greater. These same exposure levels were associated with abnormal embryo development and, at the higher concentrations, death. Some of the fractions were toxic but none was as toxic as the whole extract. In liver cells, total cellular protein and cellular lactate dehydrogenase activity were not altered by in vitro exposure to whole extract (0.05-25 micrograms/l). However, induction of cytochrome P4501A1 protein and ethoxyresorufin O-deethylase activity occurred. In the presence of whole extract, estradiol-dependent vitellogenin synthesis was reduced. Of the fractions, only fraction 1 (nonpolar) showed a similar trend, although vitellogenin synthesis inhibition was not significant. The soot extract and fractions bound to the Ah receptor and showed a significantly positive result in the gel retardation/DNA binding test. Chemical analyses using GC-MS with detection limits for 2,3,7,8-tetrachlorodibenzo-p-dioxin and dibenzofuran in the picomole range did not show presence of these compounds. Our results indicate that other chemicals associated with TCE combustion and not originally targeted for analysis may also pose health risks through dioxinlike mechanisms. PMID:8841759

Villalobos, S A; Anderson, M J; Denison, M S; Hinton, D E; Tullis, K; Kennedy, I M; Jones, A D; Chang, D P; Yang, G; Kelly, P

1996-07-01

205

Reduction of trichloroethylene and nitrate by zero-valent iron with peat  

Microsoft Academic Search

The feasibility of using zero-valent iron (ZVI) and peat mixture as in situ barriers for contaminated sediments and groundwater was investigated. Trichloroethylene (TCE) and nitrate (NO3 ), redox sensitive contaminants were reduced by ZVI and peat soil mixture under anaerobic condition. Peat was used to support the sorption of TCE, microbial activity for biodegradation of TCE and denitrification while TCE

Jee-Eun Min; Meejeong Kim; John H. Pardue; Jae-Woo Park

2008-01-01

206

QUANTIFICATION OF PRODUCTS FROM ELECTROCHEMICAL DECHLORINATION OF TRICHLOROETHYLENE USING GRANULAR-GRAPHITE ELECTRODES  

EPA Science Inventory

Electrochemical dechlorination of Trichloroethylene (TCE) in aqueous phase was studied using graphite as a cathode in a packed bed reactor in a closed system. TCE contaminated matrix solution was circulated through the electrochemical reactor where TCE was reduced at the graphite...

207

HUMAN ALPHA-7 NICOTINIC ACETYLCHOLINE RECEPTORS EXPRESSED IN XENOPUS OOCYTES ARE INHIBITED BY TRICHLOROETHYLENE.  

EPA Science Inventory

Trichloroethylene (TCE) is a volatile organic solvent (VOC) that is used as a metal degreasing agent and in paints and glue. In addition to being a commonly abused inhalant, run-off from hazardous waste sites contain enough TCE and other VOCs to contaminate ground water and near...

208

EXPOSURE DOSE REPONSE MODELING FOR THE EFFECTS OF HAZARDOUS AIR POLLUTANTS ON HEALTH: TRICHLOROETHYLENE  

EPA Science Inventory

Trichloroethylene (TCE) is a neurotoxic volatile organic compound (VOC) that is produced in large quantities as a degreasing agent and general solvent, and it appears on the list of 188 HAPs specified by the Clean Air Act Amendments of 1990. TCE was selected as a model VOC for de...

209

A Physiologically Based Pharmacokinetic Model for Trichloroethylene in the Male Long-Evans Rat  

Microsoft Academic Search

A physiologically based pharmacokinetic (PBPK) model for trichloroethylene (TCE) in the male Long-Evans (LE) rat was needed to aid in evaluation of neurotoxicity data collected in this rodent stock. The purpose of this study was to develop such a model with the greatest possible specificity for the LE rat. The PBPK model consisted of 5 compartments: brain, fat, slowly per-

J. E. Simmons; W. K. Boyes; P. J. Bushnell; J. H. Raymer; T. Limsakun; A. McDonald; Y. M. Sey; M. V. Evans

2002-01-01

210

Gas phase trichloroethylene (TCE) photooxidation and byproduct formation: photolysis vs. titania\\/silica based photocatalysis  

Microsoft Academic Search

Photooxidation of trichloroethylene (TCE) was examined in comparative study using photolysis and photocatalysis. Degussa P25 titania coated on reactor wall and deposited on silica based microporous support were used as photocatalyst. The destruction of TCE and formation of potential byproducts were investigated under steady state conditions using annular photoreactors. Experimental work involved passing polluted air containing TCE through the UV

Madjid Mohseni

2005-01-01

211

Trichloroethylene Cancer Risk: Simplified Calculation of PBPK-Based MCLs for Cytotoxic End Points  

Microsoft Academic Search

Cancer risk assessments for trichloroethylene (TCE) based on linear extrapolation from bioassay results are questionable in light of new data on TCE's likely mechanism of action involving induced cytotoxicity, for which a threshold-type dose–response model may be more appropriate. Previous studies have shown that if a genotoxic mechanism for TCE is assumed, algebraic methods can considerably simplify the use of

KENNETH T. BOGEN; Lois Swirsky Gold

1997-01-01

212

FY00 Phytoremediation of Trichloroethylene and Perchloroethylene in the Southern Sector of SRS  

SciTech Connect

This treatability study addresses the fate of volatile organic contaminants (VOCs) in an experiment that simulates a vegetated seepline supplied with trichloroethylene (TCE) and perchloroethylene (PCE) -contaminated groundwater. The primary objective is to determine how the trees uptake TCE and PCE, accumulate it, and/or transform it.

Brigmon, R.L.

2000-12-15

213

Evaluating the risk of liver cancer in humans exposed in trichloroethylene using physiological models  

Microsoft Academic Search

Trichloroethylene (TCE) is a widespread environmental pollutant. TCE is classified as a rodent carcinogen by the U.S. Environmental Protection Agency (EPA). Using the rodent cancer bioassay findings and estimates of metabolized dose, the SPA has estimated lifetime exposure cancer risks for humans that ingest TCE in drinking water or inhale TCE. In this study, a physiologically based pharmacokinetic (PB-PK) model

Jeffrey W. Fisher; Bruce C. Allen

1993-01-01

214

MICROCOSM AND IN SITU FIELD STUDIES OF ENHANCED BIOTRANSFORMATION OF TRICHLOROETHYLENE BY PHENOL-UTILIZING MICROORGANISMS  

EPA Science Inventory

The ability of different aerobic groundwater microorganisms to cometabolically degrade trichloroethylene (TCE), 1,2-cis-dichloroethylene (c-DCE), and 1,2-trans-dichloroethylene (t-DCE) was evaluated both in groundwater-fed microcosms and in situ in a shallow aquifer. icrocosms am...

215

Cardiogenic Effects of Trichloroethylene and Trichloroacetic Acid Following Exposure during Heart Specification of Avian Development  

Microsoft Academic Search

Trichloroethylene (TCE) and its metabolite trichloroacetic acid (TCA) are common drinking water contaminants in the United States. Both chemicals have been implicated in causing congenital heart defects (CHD) in human epidemiological and animal model studies. However, the latter studies have primarily focused on assessment of cardiac morphology at late embryonic stages. Here, we tested whether treating avian embryos with TCE

Victoria J. Drake; Stacy L. Koprowski; Norman Hu; Susan M. Smith; John Lough

2006-01-01

216

EFFECTS OF TRICHLOROETHYLENE AND ITS METABOLITES ON RODENT HEPATOCYTE INTERCELLULAR COMMUNICATION  

EPA Science Inventory

Chronic exposure to trichloroethylene (TCE) results in hepatocellular cancer in mice but not rats. The induction of hepatic tumors by TCE appears to be mediated through nongenotoxic or tumor promotion mechanisms. One cellular effect exhibited by a number of nongentoxic carcinogen...

217

Vapor-liquid equilibria of the trimethyl borate (1)-trichloroethylene (2) system  

SciTech Connect

Vapor-liquid equilibria for the binary system trimethyl borate (1)-trichloroethylene (2) have been measured at 101.325 kPa. Data is shown to approach ideality and could also be reasonably represented by a constant relative volatility {alpha}/sub 12/ = 1.782.

Owensby, G.S.; Plank, C.A.; Laukhuf, W.L.S. (Louisville Univ., KY (USA). Dept. of Chemical and Environmental Engineering)

1989-04-01

218

INHIBITION OF HUMAN A7 NEURONAL NICOTINIC ACETYLCHOLINE RECEPTORS BY THE VOLATILE ORGANIC SOLVENT TRICHLOROETHYLENE.  

EPA Science Inventory

Volatile organic compounds such as toleune, trichloroethylene and perchloroethylene are potent and reversible blockers of voltage-gated calcium current in nerve growth factor (NGF)-differentiated pheochromocytoma (PC12) cells. It is hypothesized that effects of VOCs on ICa contri...

219

Long-Term Capacity of Plant Mulch to Remediate Trichloroethylene in Groundwater  

EPA Science Inventory

Passive reactive barriers are commonly used to treat groundwater that is contaminated with chlorinated solvents such as trichloroethylene (TCE). A number of passive reactive barriers have been constructed with plant mulch as the reactive medium. The TCE is removed in these barr...

220

Ozonation of trichloroethylene in acetic acid solution with soluble and solid humic acid  

Microsoft Academic Search

The combined flushing and oxidation process using acetic acid and ozone has been used successfully to remove trichloroethylene (TCE) completely from contaminated soil. In this study, the effects of humic acid, a fraction of the organic matter in soil, over the performance of TCE decomposition was evaluated. TCE decomposition by ozone was enhanced by the presence of humic acid at

Martha E. Alcántara-Garduño; Tetsuji Okuda; Wataru Nishijima; Mitsumasa Okada

2008-01-01

221

Phase-transfer catalysis applied to the oxidation of nonaqueous phase trichloroethylene by potassium permanganate  

Microsoft Academic Search

The use of potassium permanganate to oxidize chlorinated solvents has been demonstrated as an effective process for treating nonaqueous phase liquids in ground-water systems. This study evaluates the effectiveness of phase-transfer catalysts (PTCs) in enhancing the degradation rate. PTCs work by transferring permanganate ion into the nonaqueous phase where it initiates oxidative decomposition. We studied the oxidation of trichloroethylene (TCE)

Yongkoo Seol; Franklin W. Schwartz

1999-01-01

222

Protective Effects of Ginkgo biloba Leaf Extracts on Trichloroethylene-Induced Human Keratinocyte Cytotoxicity and Apoptosis  

Microsoft Academic Search

The objective of this study was to assess the protective effects of Ginkgo biloba leaf extracts (EGb) on trichloroethylene (TCE)-induced cytotoxicity and apoptosis in normal human epidermal keratinocytes (NHEK). Cytotoxicity was determined by neutral red uptake, and lipid peroxidation of the cells was assessed by malondialdehyde (MDA) and superoxide dismutase (SOD). Electron microscopy and flow cytometry were used to evaluate

Q.-X. Zhu; T. Shen; D.-Y. Tu; R. Ding; Z.-Z. Liang; X.-J. Zhang

2005-01-01

223

Cytotoxicity of trichloroethylene and perchloroethylene on normal human epidermal keratinocytes and protective role of Vitamin E  

Microsoft Academic Search

Trichloroethylene (TCE) and perchloroethylene (PERC), the most common alkenyl halides, have been extensively used in industry, and can cause skin damage. To evaluate their cytotoxic potential on skin, the effects of these agents on the normal human epidermal keratinocytes (NHEK) were investigated. Their action on cell viability, membrane integrity and lipid peroxidation (LPO) was assessed by neutral red uptake (NRU)

Qi-Xing Zhu; Tong Shen; Rui Ding; Zhao-Zhao Liang; Xue-Jun Zhang

2005-01-01

224

Euro Chlor Risk Assessment for the Marine Environment Osparcom Region: North Sea - Trichloroethylene  

Microsoft Academic Search

This risk assessment on trichloroethylene (TRI) was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488\\/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs

Jean-Charles Boutonnet; Christ De Rooij; Veronique Garny; Andre Lecloux; Roger Papp; Roy S Thompson; Dolf Van Wijk

1998-01-01

225

Activated carbon adsorption of trichloroethylene (TCE) vapor stripped from TCE-contaminated water  

Microsoft Academic Search

Ground water contaminated with trichloroethylene (TCE) used in electronic, electric, dry cleaning and the like industries is often treated by air-stripping. In this treatment process, TCE in its vapor form is stripped from ground water by air stream and sometimes emitted into the atmosphere without any additional treatments. Activated carbon adsorption is one of the practical and useful processes for

Yusaku Miyake; Akiyoshi Sakoda; Hiroaki Yamanashi; Hirotaka Kaneda; Motoyuki Suzuki

2003-01-01

226

Degradation of trichloroethylene in wetland microcosms containing broad-leaved cattail and eastern cottonwood  

Microsoft Academic Search

Remediation of aquifers containing trichloroethylene (TCE) relies primarily on physical extraction of contaminated groundwater and soil. Unfortunately, this is typically expensive and does not always attain the desired treatment goals. In situ bioremediation via natural attenuation is an alternative treatment process in which TCE is transformed by indigenous microorganisms and plants. In this study, TCE was observed in a surficial

Jamie L. Bankston; Daniel L. Sola; Andrew T. Komor; Daryl F. Dwyer

2002-01-01

227

Impacts of CoSolvent Flushing on Microbial Populations Capable of Degrading Trichloroethylene  

Microsoft Academic Search

With increased application of co-solvent flushing technologies for removal of nonaqueous phase liquids from groundwater aquifers, concern over the effects of the solvent on native micro- organisms and their ability to degrade residual contaminant has also arisen. This study assessed the impact of ethanol flushing on the numbers and activity potentials of trichloroethylene (TCE)- degrading microbial populations present in aquifer

Vijayalakshmi Ramakrishnan; Andrew V. Ogram; Angela S. Lindner

2004-01-01

228

Use of specific gene analysis to assess the effectiveness of surfactant-enhanced trichloroethylene cometabolism  

Microsoft Academic Search

The objective of this study was to evaluate the effectiveness of in situ bioremediation of trichloroethylene (TCE)-contaminated groundwater using specific gene analyses under the following conditions: (1) pretreatment with biodegradable surfactants [Simple Green™ (SG) and soya lecithin (SL)] to enhance TCE desorption and dissolution, and (2) supplementation with SG, SL, and cane molasses as primary substrates to enhance the aerobic

S. H. Liang; J. K. Liu; K. H. Lee; Y. C. Kuo; C. M. Kao

229

SPERMATID MICRONUCLEUS ANALYSES OF TRICHLOROETHYLENE AND CHLORAL HYDRATE EFFECTS IN MICE  

EPA Science Inventory

Mice were exposed by inhalation to trichloroethylene (TCE), or by i.p. injection to the TCE metabolite, chloral hydrate (CH). arly spermatids were analyzed for micronucleus (MN) frequency and kinetochore status (presence or absence) using fluorochrome-labeled anti-kinetochore ant...

230

Predictive Models for Gaseous-Phase Carbon Adsorption and Humidity Effects on Trichloroethylene Adsorption.  

National Technical Information Service (NTIS)

Theoretical models were applied to the adsorption of trichloroethylene (TCE) at influent concentrations ranging from 300 to 1350 mg/cum in air on granular activated carbon at low relative humidity. The models are shown to predict both the adsorptive capac...

M. D. Werner R. L. Gross E. C. Heyse

1985-01-01

231

Effect of Trichloroethylene on Cytochrome P450 Enzymes in the Rat Liver  

Microsoft Academic Search

Trichloroethylene (TCE) is extensively used in industry, primarily as a dry cleaning solvent and a metal decreasing agent. It is no longer applied as a grain fumigant and is only occasionally used in anesthesia. The most significant uptake of TCE in humans is through inhalation of the vapour, but uptake can also occur through the skin or via the gastrointestinal

N. Hanioka; E. Omae; R. Yoda; H. Jinno; T. Nishimura; M. Ando

1997-01-01

232

A SEARCH FOR RESIDUAL BEHAVIORAL EFFECTS OF TRICHLOROETHYLENE (TCE) IN RATS EXPOSED AS YOUNG ADULTS  

EPA Science Inventory

Trichloroethylene (TCE) is a solvent of concern to the EPA due to its extensive use in industry, its prevalence in urban air, and its appearance in water supplies. Human clinical studies have associated short and long-termsolvent exposures with cognitive dysfunction including att...

233

Evaluation of biological monitoring parameters for occupational exposure to toluene  

Microsoft Academic Search

Summary A survey was conducted in a rotogravure printing plant with inhalatory and percutaneous exposure to toluene. Workers (n=9) were followed for 2 consecutive days and the frequency and duration of skin contact with toluene were monitored. In order to assess percutaneous absorption an airstream helmet was worn during one day. Urine and exhaled air samples were collected simultaneously 5

Aart C. Monster; Sanja K?zi?; Iris van de Gevel; Frederik A. de Wolff

1993-01-01

234

DRINKING WATER CRITERIA DOCUMENT FOR TOLUENE (FINAL DRAFT) 1985  

EPA Science Inventory

The Office of Drinking Water (ODW), U.S. Environmental Protection Agency has prepared a drinking water criteria document on toluene. The criteria document is an extensive review of the following topics: Physical and chemical properties of toluene toxicokinetics and human exposure...

235

CARDIOVASCULAR AND THERMOREGULATORY RESPONSE TO ORAL TOLUENE IN THE RAT.  

EPA Science Inventory

Toluene and other volatile organic compounds have often been shown to affect behavior in animals when given by inhalation, and less effective when given orally. Previous work showed that toluene increased heart rate (HR) and motor activity (MA), and reduced core temperature (Tc) ...

236

Incineration of toluene and chlorobenzene in a laboratory incinerator  

Microsoft Academic Search

This paper reports results on incineration of toluene and chlorobenzene in a small laboratory incinerator. The incinerator temperature, excess air ratio and mean residence time were varied to simulate both complete and incomplete combustion conditions. The flue gas was monitored on line using Fourier transform infrared (FTIR) spectroscopy coupling with a heated long path cell (LPC). Methane, toluene, benzene, chlorobenzene,

Zhuoxiong Mao; M. J. McIntosh; J. C. Demirgian

1992-01-01

237

Detailed Mechanism of Toluene Oxidation and Comparison with Benzene.  

National Technical Information Service (NTIS)

A detailed mechanism for the oxidation of toluene in both argon and nitrogen dilutents is presented. The mechanism was used to compute experimentally ignition delay times for shock-heated toluene-oxygen-argon mixtures with resonably good success over a wi...

D. A. Bittker

1988-01-01

238

Organic aerosol formation during the atmospheric degradation of toluene.  

PubMed

Organic aerosol formation during the atmospheric oxidation of toluene was investigated using smog chamber systems. Toluene oxidation was initiated by the UV irradiation of either toluene/air/NOx or toluene/air/CH3ONO/NO mixtures. Aerosol formation was monitored using scanning mobility particle sizers and toluene loss was monitored by in-situ FTIR spectroscopy or GC-FID techniques. The experimental results show that the reaction of OH radicals, NO3 radicals and/or ozone with the first generation products of toluene oxidation are sources of organic aerosol during the atmospheric oxidation of toluene. The aerosol results fall into two groups, aerosol formed in the absence and presence of ozone. An analytical expression for aerosol formation is developed and values are obtained for the yield of the aerosol species. In the absence of ozone the aerosol yield, defined as aerosol formed per unit toluene consumed once a threshold for aerosol formation has been exceeded, is 0.075 +/- 0.004. In the presence of ozone the aerosol yield is 0.108 +/- 0.004. This work provides experimental evidence and a simple theory confirming the formation of aerosol from secondary reactions. PMID:11348067

Hurley, M D; Sokolov, O; Wallington, T J; Takekawa, H; Karasawa, M; Klotz, B; Barnes, I; Becker, K H

2001-04-01

239

40 CFR 721.10610 - Toluene diisocyanate, polymers with polyalkylene glycol (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Toluene diisocyanate, polymers with polyalkylene glycol (generic...721.10610 Toluene diisocyanate, polymers with polyalkylene glycol (generic...generically as toluene diisocyanate, polymers with polyalkylene glycol (PMNs...

2013-07-01

240

Isolation and Characterization of Toluene-Sensitive Mutants from the Toluene-Resistant Bacterium Pseudomonas putida GM73  

PubMed Central

To understand the mechanism underlying toluene resistance of a toluene-tolerant bacterium, Pseudomonas putida GM73, we carried out Tn5 mutagenesis and isolated eight toluene-sensitive mutants. None of the mutants grew in the presence of 20% (vol/vol) toluene in growth medium but exhibited differential sensitivity to toluene. When wild-type cells were treated with toluene (1% [vol/vol]) for 5 min, about 2% of the cells could form colonies. In the mutants Ttg1, Ttg2, Ttg3, and Ttg8, the same treatment killed more than 99.9999% of cells (survival rate, <10?6). In Ttg4, Ttg5, Ttg6, and Ttg7, about 0.02% of cells formed colonies. We cloned the Tn5-inserted genes, and the DNA sequence flanking Tn5 was determined. From comparison with a sequence database, putative protein products encoded by ttg genes were identified as follows. Ttg1 and Ttg2 are ATP binding cassette (ABC) transporter homologs; Ttg3 is a periplasmic linker protein of a toluene efflux pump; both Ttg4 and Ttg7 are pyruvate dehydrogenase; Ttg5 is a dihydrolipoamide acetyltransferase; and Ttg7 is the negative regulator of the phosphate regulon. The sequences deduced from ttg8 did not show a significant similarity to any DNA or proteins in sequence databases. Characterization of these mutants and identification of mutant genes suggested that active efflux mechanism and efficient repair of damaged membranes were important in toluene resistance.

Kim, Kwang; Lee, Sungjin; Lee, Kyunghee; Lim, Dongbin

1998-01-01

241

Comparison between urinary o-cresol and toluene as biomarkers of toluene exposure.  

PubMed

The characteristics of urinary o-cresol (o-C) and urinary toluene (TOL-U) as biomarkers of occupational exposure to toluene were comparatively evaluated. One hundred healthy male rotogravure printing workers and 161 male and female control subjects were studied. Personal exposure to airborne toluene (TOL-A) during the shift was determined as a time-weighted average. Simple analytical procedures based on solid phase microextraction followed by gas chromatography/mass spectometry analysis were applied to the determination of end-shift o-C and TOL-U. Median TOL-A was 48 (6.0-162.0) mg/m3 in printers and 0.021 (<0.003-0.137) mg/m3 in controls. o-C was 0.185 (0.032-0.948) mg/g creatinine in printers and 0.027 (<0.006-0.330) mg/g creatinine in the controls. TOL-U was 7.6 (1.8-23.9) microg/L in printers and 0.140 (0.094-0.593) microg/L in the controls. According to all indices, exposure to toluene was higher in printers than in the controls. Nevertheless, the distribution of o-C in the two groups partially overlapped, whereas such behavior was not found in TOL-U. Both o-C and TOL-U in printers were correlated with TOL-A (Pearson's on log10-transformed variables r = 0.704 and 0.844, respectively) and with each other (r = 0.683). Smoking habits significantly increased the excretion of o-C but not of TOL-U. From the point of view of sampling conditions and analytical requirements, TOL-U and o-C showed similar properties, but comparison of their intrinsic characteristics showed that TOL-U had higher specificity and sensitivity, lower background values, was better correlated with airborne exposure, and was not influenced by cigarette smoking. Therefore TOL-U may be considered superior to o-C as a biomarker of occupational exposure to toluene. PMID:17162475

Fustinoni, Silvia; Mercadante, Rosa; Campo, Laura; Scibetta, Licia; Valla, Carla; Consonni, Dario; Foà, Vito

2007-01-01

242

Photocatalytic oxidation of toluene to benzaldehyde by molecular oxygen  

SciTech Connect

The visible light irradiation of aqueous solutions containing toluene, uranyl(VI) ions, and O{sub 2} results in the formation of benzaldehyde as a major product. Small amounts of PhCH{sub 2}OH are also formed. The yields of benzaldehyde are 3 times greater for toluene-h{sub 8} than for toluene-d{sub 8}, but the kinetic isotope effect for the quenching of the excited state {sup *}UO{sub 2}{sup 2+} by toluene is negligible (k{sub toluene-h(8)}/k{sub toluene-d(8)}=1.2). This and other evidence indicate that the quenching takes place in two parallel pathways. The major one involves the aromatic portion of tolune and leads to the recovery of the reactants. The minor, productive path takes place by hydrogen atom abstraction from the methyl group, followed by the oxidation of PhCH{sub 2}{sup {center_dot}}. Cumene, benzyl alcohol, and benzaldehyde react similarly. 31 refs., 5 figs., 1 tab.

Mao, Y.; Bakac, A. [Ames LAb., IA (United States)]|[Iowa State Univ., Ames, IA (United States)

1996-03-07

243

Final Amended Report of the Safety Assessment of Toluene2,5Diamine, Toluene2,5Diamine Sulfate, and Toluene3,4Diamine as Used in Cosmetics  

Microsoft Academic Search

Toluene-2,5-diamine, toluene-2,5-diamine sulfate, and toluene-3,4-diamine are diaminotoluenes used as colorants in permanent hair dyes and tints. Toluene-2,5-diamine is used in 79 products at concentrations up to 3%; toluene-2,5-diamine sulfate is used in 168 products at concentrations up to 4%. Toluene-3,4-diamine does not appear to be in current use. Previously, the Cosmetic Ingredient Review Expert Panel determined that all 3 ingredients

Christina L. Burnett; Wilma F. Bergfeld; Donald V. Belsito; Curtis D. Klaassen; James G. Marks; Ronald C. Shank; Thomas J. Slaga; Paul W. Snyder; F. Alan Andersen

2010-01-01

244

Reductive dehalogenation of chlorinated benzenes and toluenes under methanogenic conditions.  

PubMed Central

The anaerobic metabolism of chlorinated benzenes and toluenes was evaluated in soil slurry microcosms under methanogenic conditions. A mixture of hexachlorobenzene, pentachlorobenzene, and 1,2,4-trichlorobenzene (TCB) in soil slurries was biotransformed through sequential reductive dechlorination to chlorobenzene (CB). The metabolic pathway for hexachlorobenzene and pentachlorobenzene decay proceeded via 1,2,3,4-tetrachlorobenzene (TTCB)-->1,2,3-TCB + 1,2,4-TCB-->1,2-dichlorobenzene (DCB) + 1,4-DCB-->CB. In a mineral salts medium, the CB-adapted soil microorganisms dehalogenated individual 1,2,4,5-TTCB, 1,2,3,4-TTCB, 1,2,3-TCB, and 1,2,4-TCB but not 1,2,3,5-TTCB or 1,3,5-TCB. Similarly, a mixture of 2,3,6-trichlorotoluene (TCT), 2,5-dichlorotoluene (DCT), and 3,4-DCT was reductively dechlorinated in soil slurries to predominantly toluene and small amounts of 2-, 3-, and 4-chlorotoluene (CT). Toluene was further degraded. When tested individually in a mineral salts medium, the CT-adapted soil microorganisms dechlorinated several TCT and DCT isomers. Key metabolic routes for TCTs followed: 2,3,6-TCT-->2,5-DCT-->2-CT-->toluene; 2,4,5-TCT-->2,5-DCT + 3,4-DCT-->3-CT + 4-CT-->toluene. Among DCTs tested, 2,4-DCT and 3,4-DCT were dechlorinated via the removal of o- and m-chlorine, respectively, to 4-CT and subsequently to toluene via p-chlorine removal. Likewise, 2,5-DCT was dechlorinated via 2-CT to toluene. Evidently, microorganisms capable of removing o-, m-, and p-chlorines are present in the soil system, as reflected by the dechlorination of different isomers of CBs and CTs to CB and toluene, respectively. These findings help clarify the metabolic fate of chlorinated benzenes and toluenes in anaerobic environments.

Ramanand, K; Balba, M T; Duffy, J

1993-01-01

245

INFLUENCES OF PH AND CURRENT ON ELECTROLYTIC DECHLORINATION OF TRICHLOROETHYLENE AT A GRANULAR-GRAPHITE PACKED ELECTRODE  

EPA Science Inventory

Electrolytic dechlorination using a granular-graphite packed cathode is an alternative method for the remediation of chlorinated organic compounds. Its effectiveness under various conditions needs experimental investigation. Dechlorination of trichloroethylene (TCE) was conducted...

246

Tetrachloroethylene-contaminated drinking water in Massachusetts and the risk of colon-rectum, lung, and other cancers.  

PubMed Central

We conducted a population-based case-control study to evaluate the relationship between cancer of the colon-rectum (n = 326), lung (n = 252), brain (n = 37), and pancreas (n = 37), and exposure to tetrachloroethylene (PCE) from public drinking water. Subjects were exposed to PCE when it leached from the vinyl lining of drinking-water distribution pipes. Relative delivered dose of PCE was estimated using a model that took into account residential location, years of residence, water flow, and pipe characteristics. Adjusted odds ratios (ORs) for lung cancer were moderately elevated among subjects whose exposure level was above the 90th percentile whether or not a latent period was assumed [ORs and 95% confidence intervals (CIs), 3.7 (1.0-11.7), 3.3 (0.6-13.4), 6.2 (1.1-31.6), and 19.3 (2.5-141.7) for 0, 5, 7, and 9 years of latency, respectively]. The adjusted ORs for colon-rectum cancer were modestly elevated among ever-exposed subjects as more years of latency were assumed [OR and CI, 1.7 (0.8-3.8) and 2.0 (0.6-5.8) for 11 and 13 years of latency, respectively]. These elevated ORs stemmed mainly from associations with rectal cancer. Adjusted ORs for rectal cancer among ever-exposed subjects were more elevated [OR and CI, 2.6 (0. 8-6.7) and 3.1 (0.7-10.9) for 11 and 13 years of latency, respectively] than were corresponding estimates for colon cancer [OR and CI, 1.3 (0.5-3.5) and 1.5 (0.3-5.8) for 11 and 13 years of latency, respectively]. These results provide evidence for an association between PCE-contaminated public drinking water and cancer of the lung and, possibly, cancer of the colon-rectum.

Paulu, C; Aschengrau, A; Ozonoff, D

1999-01-01

247

Prenatal exposure to tetrachloroethylene-contaminated drinking water and the risk of congenital anomalies: a retrospective cohort study  

PubMed Central

Background Prior animal and human studies of prenatal exposure to solvents including tetrachloroethylene (PCE) have shown increases in the risk of certain congenital anomalies among exposed offspring. Objectives This retrospective cohort study examined whether PCE contamination of public drinking water supplies in Massachusetts influenced the occurrence of congenital anomalies among children whose mothers were exposed around the time of conception. Methods The study included 1,658 children whose mothers were exposed to PCE-contaminated drinking water and a comparable group of 2,999 children of unexposed mothers. Mothers completed a self-administered questionnaire to gather information on all of their prior births, including the presence of anomalies, residential histories and confounding variables. PCE exposure was estimated using EPANET water distribution system modeling software that incorporated a fate and transport model. Results Children whose mothers had high exposure levels around the time of conception had an increased risk of congenital anomalies. The adjusted odds ratio of all anomalies combined among children with prenatal exposure in the uppermost quartile was 1.5 (95% CI: 0.9, 2.5). No meaningful increases in the risk were seen for lower exposure levels. Increases were also observed in the risk of neural tube defects (OR: 3.5, 95% CI: 0.8, 14.0) and oral clefts (OR 3.2, 95% CI: 0.7, 15.0) among offspring with any prenatal exposure. Conclusion The results of this study suggest that the risk of certain congenital anomalies is increased among the offspring of women who were exposed to PCE-contaminated drinking water around the time of conception. Because these results are limited by the small number of children with congenital anomalies that were based on maternal reports, a follow-up investigation should be conducted with a larger number of affected children who are identified by independent records.

2009-01-01

248

Neurotoxicologic examination of rats exposed to 1,1,2,2-tetrachloroethylene (perchloroethylene) vapor for 13 weeks.  

PubMed

Large evoked potential and EEG changes occurred in a pilot study in Fischer 344 rats during exposure to 800 ppm of 1,1,2,2-tetrachloroethylene [perchloroethylene (Perc)], a cleaning solvent with anesthetic properties. In the main study, rats were evaluated for persistent nervous system effects the week following exposure to 0, 50, 200, or 800 ppm Perc for 6 h/day, 5 days/week, for 13 weeks. The only effect related to treatment was in the flash evoked potential (FEP-V), recorded from the visual cortex. The longer latency potentials (N3) of the FEP-V had a greater amplitude in the 800 ppm Perc group. The FEP-Vs were of normal shape and latency. Although mild neurotoxicity could not be ruled out completely, amplitude changes in N3 can occur for a variety of psychophysiological reasons other than neurotoxicity. Consequently, as a stand-alone finding, the toxicologic significance of the larger FEP in the 800 ppm exposure group was unknown. Other data did not support a diagnosis of neurotoxicity. No treatment-related alterations were noted in expanded clinical observations, in the FEP recorded from the cerebellum (as opposed to visual cortex FEP-V), or in auditory, somatosensory, or caudal nerve evoked potentials. No treatment-related lesions were noted during histopathologic examination of eyes, optic nerves, optic tract, or multiple sections of brain, spinal cord, peripheral nerves, or limb muscles. The no-observed-effect-level (NOEL) was 200 ppm, based on increased amplitude of the longer latency potentials of the FEP at 800 ppm. PMID:9511173

Mattsson, J L; Albee, R R; Yano, B L; Bradley, G; Spencer, P J

249

Rheology of asphaltene-toluene/water interfaces.  

PubMed

The stability of water-in-crude oil emulsions is frequently attributed to a rigid asphaltene film at the water/oil interface. The rheological properties of these films and their relationship to emulsion stability are ill defined. In this study, the interfacial tension, elastic modulus, and viscous modulus were measured using a drop shape analyzer for model oils consisting of asphaltenes dissolved in toluene for concentrations varying from 0.002 to 20 kg/m(3). The effects of oscillation frequency, asphaltene concentration, and interface aging time were examined. The films exhibited viscoelastic behavior. The total modulus increased as the interface aged at all asphaltene concentrations. An attempt was made to model the rheology for the full range of asphaltene concentration. The instantaneous elasticity was modeled with a surface equation of state (SEOS), and the elastic and viscous moduli, with the Lucassen-van den Tempel (LVDT) model. It was found that only the early-time data could be modeled using the SEOS-LVDT approach; that is, the instantaneous, elastic, and viscous moduli of interfaces aged for at most 10 minutes. At longer interface aging times, the SEOS-LVDT approach was invalid, likely because of irreversible adsorption of asphaltenes on the interface and the formation of a network structure. PMID:16316096

Sztukowski, Danuta M; Yarranton, Harvey W

2005-12-01

250

Transformations of toluene radical cation in ZSM-5 and Silicalite.  

National Technical Information Service (NTIS)

Toluene radical cations produced by (gamma) irradiation at 77 K in ZSM-5 and Silicalite (isomorphous with ZSM-5 but nonpolar) undergo a reversible transformation to the norbornadiene radical cation at temperatures (le)150K. The transformation occurs to a ...

M. V. Barnabas D. W. Werst A. D. Trifunac

1992-01-01

251

Preparation of Toluenes Specifically Labelled with C-14.  

National Technical Information Service (NTIS)

The attempt to prepare toluene-2 C-14 starting from ethyl acetoacetate failed because the reaction of sodium ethyl acetoacetate with dibromopropane could not be performed. This labelling was also attempted starting from methyl tetrahydropyran. This synthe...

F. Hoessel

1977-01-01

252

Incineration of toluene and chlorobenzene in a laboratory incinerator.  

National Technical Information Service (NTIS)

This paper reports experimental results on the incineration of toluene and chlorobenzene in a small laboratory incinerator. Temperature of the incinerator, excess air ratio and mean residence time were varied to simulate both complete and incomplete combu...

Z. Mao M. J. Mcintosh J. C. Demirgian

1992-01-01

253

Incineration of toluene and chlorobenzene in a laboratory incinerator.  

National Technical Information Service (NTIS)

This paper reports results on incineration of toluene and chlorobenzene in a small laboratory incinerator. The incinerator temperature, excess air ratio and mean residence time were varied to simulate both complete and incomplete combustion conditions. Th...

Z. Mao M. J. McIntosh J. C. Demirgian

1992-01-01

254

Metabolism of benzene, toluene, and xylene hydrocarbons in soil  

Microsoft Academic Search

Enrichment cultures obtained from soil exposed to benzene, toluene, and xylene (BTX) mineralized benzene and toluene but cometabolized only xylene isomers, forming polymeric residues. This observation prompted the authors to investigate the metabolism of ¹⁴C-labeled BTX hydrocarbons in soil, either individually or as mixtures. BTX-supplemented soil was incubated aerobically for up to 4 weeks in a sealed system that automatically

C.-W. TSAO; H.-G. SONG; R. Bartha

1998-01-01

255

Secondary organic aerosol formation from m -xylene, toluene, and benzene  

Microsoft Academic Search

Secondary organic aerosol (SOA) formation from the photooxidation of m-xylene, toluene, and benzene is in- vestigated in the Caltech environmental chambers. Exper- iments are performed under two limiting NOx conditions; under high-NOx conditions the peroxy radicals (RO2) react only with NO, while under low-NOx conditions they react only with HO2. For all three aromatics studied (m-xylene, toluene, and benzene), the

N. L. Ng; J. H. Kroll; A. W. H. Chan; P. S. Chhabra; R. C. Flagan; J. H. Seinfeld

2007-01-01

256

Hydrogenation kinetics of toluene on Pt\\/ZSM-22  

Microsoft Academic Search

Kinetic experiments on the hydrogenation of toluene were performed on 0.5wt.% Pt\\/ZSM-22 at temperatures in the range 423–498K, H2 inlet partial pressures of 100–300kPa and toluene inlet partial pressures of 10–60kPa. Construction of a kinetic model was based on a critical evaluation of available literature data on the hydrogenation of aromatic components together with physicochemical studies on the interaction of

Joris W. Thybaut; Mark Saeys; Guy B. Marin

2002-01-01

257

Psychomotor performance and subjective symptoms at low level toluene exposure  

Microsoft Academic Search

Objectives: Possible effects of long term occupational exposure to toluene below the level of 100 ppm on psychomotor performance and subjective symptoms were investigated in a cross sectional approach.Methods: From German rotogravure printing plants 278 male workers, mean age 39.8 years, mean duration of employment 14.9 years, were examined. A mean lifetime weighted average exposure (LWAE) of 45.1 ppm toluene

M Zupanic; P Demes; A Seeber

2002-01-01

258

Solar\\/UV?induced photocatalytic degradation of volatile toluene  

Microsoft Academic Search

The degradations of gaseous toluene (2–20 ppmv) by solar irradiation (solar), solar irradiation and ozone (solar + O3), solar photocatalytic reaction (solar + TiO2) and solar photocatalytic reaction in the presence of ozone (solar + O3 + TiO2) were studied in a pilot plant. The effects of the inlet concentration of toluene, flow rate and relative humidity on the decomposition

Fares Al Momani; Nabeel Jarrah

2009-01-01

259

EFFECTS OF PH ON DECHLORINATION OF TRICHLOROETHYLENE BY ZERO-VALENT IRON  

EPA Science Inventory

The surface normalized reaction rate constants (ksa) of trichloroethylene (TCE) and zero-valent iron (ZVI) was quantified in batch reactors at pH values between 1.7 and 10. The ksa of TCE linearly decreased from 0.044 to 0.009 L/hr-m2 between pH 3.8 and 8.0, whereas the ksa at pH...

260

Diversity in kinetics of trichloroethylene-degrading activities exhibited by phenol-degrading bacteria  

Microsoft Academic Search

Whole-cell kinetics of phenol- and trichloroethylene (TCE)-degrading activities expressed by 13 phenol-degrading bacteria were analyzed. The Ks (apparent affinity constant in Haldane's equation) values for TCE were unexpectedly diverse, ranging from 11 µM to over 800 µM. The Vmax\\/Ks values for phenol were three orders of magnitude higher than the values for TCE in all bacteria analyzed, suggesting that these

Hiroyuki Futamata; Shigeaki Harayama; Kazuya Watanabe

2001-01-01

261

Tissue Repair Response as a Function of Dose during Trichloroethylene Hepatotoxicity  

Microsoft Academic Search

Trichloroethylene (TCE), a widely used organic solvent and degreasing agent, is regarded as a hepatotoxicant. The objective of the present studies was to investigate whether the extent and timeliness of tissue repair has a determining influence on the ultimate outcome of hepatotoxicity. Male Sprague–Dawley rats (200–250 g) were injected with a 10-fold dose range of TCE and hepatotoxicity and tissue

Madhusudan G. Soni; Raja S. Mangipudy; Moiz M. Mumtaz; Harihara M. Mehendale

1998-01-01

262

Anaerobic dechlorination of trichloroethylene (TCE) to ethylene using complex organic materials  

Microsoft Academic Search

Reductive dechlorination of trichloroethylene (TCE) to ethylene was supported by complex organic matter such as cane molasses and ligno-cellulosic materials as a substrate and electron donor under methanogenic conditions. The studies were performed with an anaerobic dechlorinating, methanogenic microbial consortium at 20–22°C. A high molar ratio between methane and ethylene (158mol\\/mol) was observed during rapid dechlorination of TCE with cane

Wei-Min Wu; Jeffery Nye; Mahendra K. Jain; Robert F. Hickey

1998-01-01

263

Phylogenetic analysis of trichloroethylene-degrading bacteria newly isolated from soil polluted with this contaminant  

Microsoft Academic Search

Five methanotrophs (strains 18-2, EB1, KSWIII, KSPIII and KSPIII) and three aromatic compound oxidizers (strains KP22, KP24 and KT1) were isolated from the natural field polluted with trichloroethylene (TCE). Phylogenetic analysis based on 16S rRNA gene sequence suggested that all of the isolates belonged to the class Proteobacteria. Two of the methanotrophic isolates, strains 18-2 and EB1, were closely related

Satoshi Hanada; Toru Shigematsu; Katsutoshi Shibuya; Masahiro Eguchi; Takeshi Hasegawa; Fusako Suda; Yoichi Kamagata; Takahiro Kanagawa; Ryuichiro Kurane

1998-01-01

264

Fasciitis (not scleroderma) following prolonged exposure to an organic solvent (trichloroethylene).  

PubMed

We describe 2 cases of diffuse fasciitis with eosinophilia (DFE) associated with prolonged exposure to the industrial solvent trichloroethylene (TCE). The medical and personal histories, examinations, and laboratory and pathological investigations were reviewed and summarized. The 2 case reports, representing the first and 2nd cases of DFE associated with TCE, were compared with 8 reported cases of systemic sclerosis associated with TCE and suggest a direct association between TCE exposure and the development of fasciitis (DFE). PMID:7983667

Waller, P A; Clauw, D; Cupps, T; Metcalf, J S; Silver, R M; Leroy, E C

1994-08-01

265

Stable isotope (C, Cl, and H) fractionation during vaporization of trichloroethylene  

SciTech Connect

Stable isotope fractionation during vaporization of trichloroethylene has been measured, with possible application as a technique to investigate subsurface behavior. The equilibrium value of {Delta}{sup 13}C{sub vapor-liquid} has been measured between 5 and 35 C, and {Delta}{sup 13}C{sub vapor-liquid}, {Delta}{sup 37}Cl{sub vapor-liquid}, and {Delta}D{sub vapor-liquid} have been measured during progressive evaporation of liquid trichloroethylene at 22 {+-} 2 C. Equilibrium values of {Delta}{sup 13}C{sub vapor-liquid} show a total range of 0.07--0.82{per{underscore}thousand}, with a trend of decreasing {Delta}{sup 13}C{sub vapor-liquid} with increasing temperature, from approximately +0.7{per{underscore}thousand} at 5--15 C to approximately +0.1{per{underscore}thousand} at 35 C. Progressive evaporation experiments yield values of {Delta}{sup 13}C{sub vapor-liquid} = +0.35{per{underscore}thousand} and +0.24{per{underscore}thousand}, {Delta}{sup 37}Cl{sub vapor-liquid} = {minus}1.64{per{underscore}thousand}, and {Delta}D{sub vapor-liquid} = +8.9{per{underscore}thousand}. The positive values for carbon and hydrogen isotope fractionation, while unexpected, are consistent with available quantitative and qualitative data for trichloroethylene and other contaminant hydrocarbons, but a satisfactory explanation for these observations, particularly in combination with the negative value for chlorine, remains elusive, Vapor-liquid fractionation factors have application to the investigation of the behavior of trichloroethylene at contaminated sites, particularly sites undergoing remediation by techniques such as soil vapor extraction and soil bioventing.

Poulson, S.R.; Drever, J.I.

1999-10-15

266

Decomposition of trichloroethylene and 2,4-dichlorophenol by ozonation in several organic solvents  

Microsoft Academic Search

The effects of chemical characteristics of organic solvents on the decomposition rate constants of undissociative trichloroethylene (TCE) and dissociative 2,4-dichlorophenol (2,4-DCP) by ozonation were studied. The TCE and 2,4-DCP decomposition by ozonation in organic solvents followed to the first-order reaction kinetics with respect to TCE or 2,4-DCP concentration. The orders of the rate constants among organic solvents for undissociative TCE

Tsung-Yueh Tsai; Kiyokazu Okawa; Yoichi Nakano; Wataru Nishijima; Mitsumasa Okada

2004-01-01

267

Effect of phosphate and sediment bacteria on trichloroethylene dechlorination with zero valent iron  

Microsoft Academic Search

The effects of sediment-isolated bacteria and phosphate on the efficacy of zero valent iron (ZVI) for the dechlorination of trichloroethylene (TCE) were examined in batch experiments. TCE (0.3 mM) and a constant concentration of sediment bacteria were simultaneously exposed to ZVI in the presence of 0 mmol, 15 mmol, and 30 mmol of phosphate. TCE profiles, starting from 0.3 mM

Jee-Eun Min; In Sun Park; Seokoh Ko; Won Sik Shin; Jae-Woo Park

2009-01-01

268

Impact of Vegetable Oil on Distribution of Trichloroethylene in Groundwater During Enhanced Bioremediation  

Microsoft Academic Search

Vegetable oils are increasingly being used as long-term carbon donors to stimulate reductive dechlorination of trichloroethylene (TCE). Besides potential enhancement of biodegradation, the addition of vegetables oils may impact TCE fate and distribution within the aquifer by acting as non-aqueous phase liquids (NAPL). Distribution coefficients for TCE between groundwater and four vegetable oils were determined using a slow-stir technique. Log

Min Pu; R. Ryan Dupont; William J. Doucette

2008-01-01

269

A study of photocatalytic degradation of trichloroethylene in vapor phase on TiO 2 photocatalyst  

Microsoft Academic Search

This investigation used a packed-bed reactor filled with coated titanium dioxide glass beads which was activated by a 365 nm UV light for heterogeneous photocatalytic decomposition of trichloroethylene under different conditions of flowrate, oxygen content, moisture and light intensity. For the flowrate of feed gas between 100–500 mL\\/min, the reaction rates increased with an increasing flowrate below 300 mL\\/min. When

Kuo-Hua Wang; Huan-Hung Tsai; Yung-Hsu Hsieh

1998-01-01

270

A new bacterial biosensor for trichloroethylene detection based on a three-dimensional carbon nanotubes bioarchitecture  

Microsoft Academic Search

Trichloroethylene (TCE), a suspected human carcinogen, is one of the most common volatile groundwater contaminants. Many different\\u000a methodologies have already been developed for the determination of TCE and its degradation products in water, but most of\\u000a them are costly, time-consuming and require well-trained operators. In this work, a fast, sensitive and miniaturised whole\\u000a cell conductometric biosensor was developed for the

Mouna Hnaien; Florence Lagarde; Joan Bausells; Abdelhamid Errachid; Nicole Jaffrezic-Renault

2011-01-01

271

Kinetics of Chlorinated Hydrocarbon Degradation by Methylosinus trichosporium OB3b and Toxicity of Trichloroethylene  

Microsoft Academic Search

The kinetics of the degradation of trichloroethylene (TCE) and seven other chlorinated aliphatic hydrocarbons by Methylosinus trichosporium OB3b were studied. All experiments were performed with cells grown under copper stress and thus expressing soluble methane monooxygenase. Compounds that were readily degraded included chloroform, trans-1,2-dichloroethylene, and TCE, with Vmax values of 550, 330, and 290 nmol min-1 mg of cells-1, respectively.

Dick B. Janssen; Jacob J. van der Waarde; Johannes Y. Oedzes; Roelof Oldenhuis

1991-01-01

272

Photooxidation and biotrickling filtration for controlling industrial emissions of trichloroethylene and perchloroethylene  

Microsoft Academic Search

A two-stage process integrating ultraviolet oxidation and biotrickling filtration (UV–BTF) was developed for treatment of industrial air streams contaminated with trichloroethylene (TCE) and perchloroethylene (PCE). Laboratory-scale studies demonstrated that the UV–BTF system consistently achieved contaminant removal efficiencies of 99–100% under optimal conditions. The UV–BTF process employs an advanced oxidation process (AOP) such as UV photooxidation as pretreatment for alleviating biological

Walter Den; Varadarajan Ravindran; Massoud Pirbazari

2006-01-01

273

Momentary Brain Concentration of Trichloroethylene Predicts the Effects on Rat Visual Function  

Microsoft Academic Search

The relationship between the concentration of trichloroethylene (TCE) in the brain and changes in brain function, indicated by the amplitude of steady-state pattern-elicited visual evoked potentials (VEP), was evaluated in Long-Evans rats. VEPs were recorded from visual cortex following stimulation of the eyes and, thus, reflect the function of the afferent visual pathway and, in broad terms, may be indicative

William K. Boyes; Mark Bercegeay; Todd Krantz; Marina Evans; Vernon Benignus; Jane Ellen Simmons

2005-01-01

274

Atrioventricular conduction abnormality and hyperchloremic metabolic acidosis in toluene sniffing.  

PubMed

Toluene is an aromatic hydrocarbon with widespread industrial use as an organic solvent. As a result of the euphoric effect and availability of these substances, inhalation of toluene-based products is popular among young adults and children. Chronic or acute exposure is known to cause acid-base and electrolyte disorders, and to be toxic to the nervous and hematopoietic systems. We report a 38-year-old man who suffered from general muscular weakness of all extremities after toluene sniffing, which was complicated with hypokalemic paralysis, atrioventricular conduction abnormality, and normal anion gap hyperchloremic metabolic acidosis. Renal function, serum potassium and acid-base status normalized within 3 days after aggressive potassium chloride and intravenous fluid replacement. Electrocardiography showed regression of first-degree atrioventricular block. Exposure to toluene can lead to cardiac arrhythmias and sudden sniffing death syndrome. Tachyarrhythmia is the classical manifestation of toluene cardiotoxicity. Atrioventricular conduction abnormalities have been rarely mentioned in the literature. Knowledge of the toxicology and medical complications associated with toluene sniffing is essential for clinical management of these patients. PMID:21982470

Tsao, Jian-Hsiung; Hu, Yu-Hui; How, Chorng-Kuang; Chern, Chii-Hwa; Hung-Tsang Yen, David; Huang, Chun-I

2011-09-09

275

Toluene Diffusion and Reaction in Unsaturated Pseudomonas putida Biofilms  

PubMed Central

Biofilms are frequently studied in the context of submerged or aquatic systems. However, much less is known about biofilms in unsaturated systems, despite their importance to such processes as food spoilage, terrestrial nutrient cycling, and biodegradation of environmental pollutants in soils. Using modeling and experimentation, we have described the biodegradation of toluene in unsaturated media by bacterial biofilms as a function of matric water potential, a dominant variable in unsaturated systems. We experimentally determined diffusion and kinetic parameters for Pseudomonas putida biofilms, then predicted biodegradation rates over a range of matric water potentials. For validation, we measured the rate of toluene depletion by intact biofilms and found the results to reasonably follow the model predictions. The diffusion coefficient for toluene through unsaturated P. putida biofilm averaged 1.3 × 10?7 cm2/s, which is approximately two orders of magnitude lower than toluene diffusivity in water. Our studies show that, at the scale of the microbial biofilm, the diffusion of toluene to biodegrading bacteria can limit the overall rate of biological toluene depletion in unsaturated systems.

Holden, Patricia A.; Hunt, James R.; Firestone, Mary K.

2010-01-01

276

Reproductive and developmental toxicity of toluene: a review.  

PubMed Central

Toluene is a widely used industrial solvent, and humans may also have high exposures to toluene from the deliberate inhalation ("sniffing") of paint reducer, paint thinner, or paint for their narcotic effects. A number of case reports describe neonatal effects that have been attributed to toluene abuse during pregnancy. These effects may include intrauterine growth retardation, premature delivery, congenital malformations, and postnatal developmental retardation. The possibility of exposures to other fetotoxic agents, either as impurities or admixtures in toluene-containing products, or by deliberate or accidental exposures to other chemicals or drugs, cannot be excluded in these cases. The fetotoxic effects of toluene have been demonstrated in controlled studies in animals and are comparable to those observed in humans who have abused toluene-containing products before or during pregnancy. Intrauterine developmental retardation is the most clearly established effect in animals, as evidenced by decreased late fetal weight and retarded skeletal development. There is also limited evidence in rodents for skeletal and kidney abnormalities, as well as some evidence for effects on postnatal physical and possibly neurobehavioral development. Estimated daily exposures from experimental studies in animals are compared to estimated human daily intakes at the occupational permissible exposure level and at the level reported to produce euphoria in humans. Acceptable human intakes under California's Proposition 65 and under U.S. Environmental Protection Agency procedures are discussed.

Donald, J M; Hooper, K; Hopenhayn-Rich, C

1991-01-01

277

Diffusion of trichloroethylene through the threaded joints of PVC (polyvinylchloride) pipe  

SciTech Connect

The data engineers and scientists use to determine if the groundwater supply is contaminated are derived from analysis of samples taken largely from monitoring wells. For these data to be reliable several factors must be considered. One factor is the integrity of the monitoring well. In this project, emphasis has been placed on the potential impact on water quality caused by diffusion across the threaded joints of PVC pipe. In this study, the diffusion of trichloroethylene across several common types of threaded joints (i.e., square flush, modified ACME, modified ACME stub, and ACME) has been measured. Samples were obtained from the water inside the pipe sections and analyzed for trichloroethylene by gas chromatography. Breakthrough occurs within days of the samples being placed in the baths. The softened PVC joints of the pipes in the pure trichloroethylene split before the first sample interval of 1.5 weeks. The data show great variability in casting joints from the same manufacturer, and indicate a need for increased precision in the manufacturing of the PVC pipe joints. A one-dimensional diffusion model is used to determine an equivalent gap size through which the diffusion occurs. Flow rates through the threaded joints are calculated by using the equivalent gap width and a formula for flow through a rectangular duct running full. Comparison of the results of the gap size calculations and of the flow rates is presented. 20 refs., 13 figs. 11 tabs.

Jerome, K.M. (Pennsylvania State Univ., University Park, PA (USA). Dept. of Civil Engineering)

1990-12-01

278

Oxidative degradation of trichloroethylene adsorbed on active carbons: Use of microwave energy  

SciTech Connect

Chlorinated hydrocarbon compounds (CHCl), such as chlorinated alkanes/alkenes, benzene and biphenyl etc, represent an important fraction of the industrial hazardous wastes produced. Trichloroethylene (TCE) can be removed from waste streams by adsorption on active carbons. The primary objective of the present work was to study the detoxification in air-stream of TCE adsorbed on different types of active carbons using in situ microwave heating. A secondary objective was to examine the regeneration of used carbons from the effects of repeated cyclic operations (adsorption- detoxification). The experimental study has shown that trichloroethylene adsorbed on active carbon can be oxidatively degradated in presence of microwave radiation. Energy can be transferred efficiently to the reaction sites without losing heat to the surrounding vessel. One of the decomposition product of trichloroethylene is free chlorine which is held very strongly on active carbon. Hydrochloric acid on the other hand seems to be less strongly held and appears in large concentration in the exit gas. Production of free chlorine can be avoided by using chlorohydrocarbon mixed with sufficient internal hydrogen. This is also expected to minimize the problem of carbon regeneration encountered in this study. The results obtained from studies on the oxidative degradation of TCE under microwave radiation are promising in a number of respects: (1) the detoxification of TCE adsorbed on active carbon can be conducted at moderate (<400{degree}C) temperatures, and (2) the used carbon bed can be regenerated. A patent on the process has been issued. 9 refs., 2 figs., 2 tabs.

Varma, R.; Nandi, S.P.

1991-01-01

279

Methyl rotor dependent vibrational interactions in toluene.  

PubMed

The methyl rotor dependence of a three state Fermi resonance in S1 toluene at ?460 cm(-1) has been investigated using two-dimensional laser induced fluorescence. An earlier time-resolved study has shown the Fermi resonance levels to have different energy spacings at the two lowest methyl rotor states, m = 0 and 1 [J. A. Davies, A. M. Green, and K. L. Reid, Phys. Chem. Chem. Phys. 12, 9872 (2010)]. The overlapped m = 0 and 1 spectral features have been separated to provide direct spectral evidence for the m dependence of the resonance. The resonance has been probed at m = 3a(") 1 for the first time and found to be absent, providing further evidence for a large change in the interaction with m. Deperturbing the resonance at m = 0 and 1 reveals that the m dependence arises through differences in the separations of the "zero-order," locally coupled states. It is shown that this is the result of the local "zero-order" states being perturbed by long-range torsion-vibration coupling that shifts their energy by small amounts. The m dependence of the shifts arises from the ?m = ±3n (n = 1, 2, ...) coupling selection rule associated with torsion-rotation coupling in combination with the m(2) scaling of the rotor energies, which changes the ?E for the interaction for each m. There is also an increase in the number of states that can couple to m = 1 compared with m = 0. Consideration of the magnitude of reported torsion-rotation coupling constants suggests that this effect is likely to be pervasive in molecules with methyl rotors. PMID:23574222

Gascooke, Jason R; Lawrance, Warren D

2013-04-01

280

Methyl rotor dependent vibrational interactions in toluene  

NASA Astrophysics Data System (ADS)

The methyl rotor dependence of a three state Fermi resonance in S1 toluene at ~460 cm-1 has been investigated using two-dimensional laser induced fluorescence. An earlier time-resolved study has shown the Fermi resonance levels to have different energy spacings at the two lowest methyl rotor states, m = 0 and 1 [J. A. Davies, A. M. Green, and K. L. Reid, Phys. Chem. Chem. Phys. 12, 9872 (2010)]. The overlapped m = 0 and 1 spectral features have been separated to provide direct spectral evidence for the m dependence of the resonance. The resonance has been probed at m = 3a''1 for the first time and found to be absent, providing further evidence for a large change in the interaction with m. Deperturbing the resonance at m = 0 and 1 reveals that the m dependence arises through differences in the separations of the ``zero-order,'' locally coupled states. It is shown that this is the result of the local ``zero-order'' states being perturbed by long-range torsion-vibration coupling that shifts their energy by small amounts. The m dependence of the shifts arises from the ?m = +/-3n (n = 1, 2, ...) coupling selection rule associated with torsion-rotation coupling in combination with the m2 scaling of the rotor energies, which changes the ?E for the interaction for each m. There is also an increase in the number of states that can couple to m = 1 compared with m = 0. Consideration of the magnitude of reported torsion-rotation coupling constants suggests that this effect is likely to be pervasive in molecules with methyl rotors.

Gascooke, Jason R.; Lawrance, Warren D.

2013-04-01

281

Soot formation in shock-tube pyrolysis of toluene- n-heptane and toluene-iso-octane mixtures  

Microsoft Academic Search

Soot formation during the pyrolysis of argon-diluted mixtures of toluene and n-heptane and of toluene and iso-octane in a reflected-shock tube was studied. Soot induction times and rates of formation measured at 632.8 nm by laser beam attenuation showed an Arrhenius dependence on reflected-shock temperature. The maximum in bell-shaped distribution of soot yield and concentration as a function of temperature

A. Alexiou; A. Williams

1995-01-01

282

Nonrecombinant Genetic Modification of Aquifer Bacteria to Achieve Constitutive Degradation of Trichloroethylene.  

National Technical Information Service (NTIS)

Aquifer bacteria were isolated for their capacity to predominate following nutrient enrichment (field application vectors (FAVs)), and screened as hosts for the Tn5 containing, constitutive toluene ortho-monoxygenase (Tom) expressing plasmid: TOM(31c) (wh...

M. S. Shields

1996-01-01

283

Stable Hydrogen and Carbon Isotope Fractionation during Microbial Toluene Degradation: Mechanistic and Environmental Aspects  

Microsoft Academic Search

Primary features of hydrogen and carbon isotope fractionation during toluene degradation were studied to evaluate if analysis of isotope signatures can be used as a tool to monitor biodegradation in contaminated aquifers. D\\/H hydrogen isotope fractionation during microbial degradation of toluene was measured by gas chromatography. Per-deuterated toluene-d8 and nonlabeled toluene were supplied in equal amounts as growth substrates, and

BARBARA MORASCH; HANS H. RICHNOW; BERNHARD SCHINK; RAINER U. MECKENSTOCK

2001-01-01

284

Immunotoxicological evaluation of toluene exposure via drinking water in mice  

SciTech Connect

Toluene is a known contaminant found in trace amounts in groundwater. Male CD-1 mice were exposed to 0, 17, 80, and 405 mg/liter toluene in drinking water for 4 weeks. Immune function assays were selected to evaluate specific humoral and cell-mediated immunity, interleukin-2 (IL-2) activity, hematology, along with general toxicity. Toluene produced an increase in liver weight and decrease in thymus mass at the highest dose. No effects on body weights and hematological parameters, including erythrocytes, leukocytes, and their differentials were noticed. Mitogenesis by lipopolysaccharide, pokeweed mitogen, concanavalin A, and phytohemagglutinin were suppressed in splenocytes from treated mice. Splenocyte lymphoproliferation to alloantigens decreased at the 405 mg/liter concentration only. Numbers of sheep red blood cell (SRBC)-specific plaque-forming cells decreased in the highest dosed animals; however, no significant change was observed in the serum {alpha}-SRBC antibody level. Toluene also adversely affected IL-2 synthesis at the 405 mg/liter concentration. Findings suggest that alteration of immune functions of mice ingesting toluene was generally evident at relatively high doses, except for splenic lymphocyte responses to selected mitogens.

Hsieh, G.C.; Sharma, R.P.; Parker, R.D.R. (Utah State Univ., Logan (USA))

1989-06-01

285

Dielectric relaxation of polychlorinated biphenyl/toluene mixtures: component dynamics.  

PubMed

The dynamics of homogenous polychlorinated biphenyl (PCB54)/toluene mixtures have been investigated by means of broadband dielectric spectroscopy. The mixture presents dynamical heterogeneity, alike miscible polymer blends, which is manifested with the presence of two relaxational processes. The relatively slow one has been attributed to the motion of PCB54 in the mixture, whereas the relatively fast one was related to the toluene dynamics in the mixture. These results have been interpreted according to the self-concentration concept, first introduced to describe the dynamics of miscible polymer blends, which relies on the limited size of the cooperative length scale in glass-forming liquids. The self-concentration concept has been incorporated in the Adam-Gibbs theory of the glass transition relating the characteristic relaxation time and the length scale for structural relaxation to the configurational entropy. This allowed the determination of the cooperative length scale of PCB54 and toluene both in mixture and alone through the fitting of a single parameter, namely, that connecting the cooperative length scale to the configurational entropy. This length scale resulted to be in the range of 1-2 nm for all systems. Finally, the out-of-equilibrium dynamics of toluene induced by the selective freezing in of PCB54 has been examined and its relation to the Johari-Goldstein relaxation of pure toluene was critically discussed. PMID:18554030

Cangialosi, Daniele; Alegría, Angel; Colmenero, Juan

2008-06-14

286

Dielectric relaxation of polychlorinated biphenyl/toluene mixtures: Component dynamics  

NASA Astrophysics Data System (ADS)

The dynamics of homogenous polychlorinated biphenyl (PCB54)/toluene mixtures have been investigated by means of broadband dielectric spectroscopy. The mixture presents dynamical heterogeneity, alike miscible polymer blends, which is manifested with the presence of two relaxational processes. The relatively slow one has been attributed to the motion of PCB54 in the mixture, whereas the relatively fast one was related to the toluene dynamics in the mixture. These results have been interpreted according to the self-concentration concept, first introduced to describe the dynamics of miscible polymer blends, which relies on the limited size of the cooperative length scale in glass-forming liquids. The self-concentration concept has been incorporated in the Adam-Gibbs theory of the glass transition relating the characteristic relaxation time and the length scale for structural relaxation to the configurational entropy. This allowed the determination of the cooperative length scale of PCB54 and toluene both in mixture and alone through the fitting of a single parameter, namely, that connecting the cooperative length scale to the configurational entropy. This length scale resulted to be in the range of 1-2 nm for all systems. Finally, the out-of-equilibrium dynamics of toluene induced by the selective freezing in of PCB54 has been examined and its relation to the Johari-Goldstein relaxation of pure toluene was critically discussed.

Cangialosi, Daniele; Alegría, Angel; Colmenero, Juan

2008-06-01

287

Similarities of toluene and o-cresol neuroexcitation in rats.  

PubMed

Exposure to high concentrations of toluene vapors, or to intravenous o-cresol (a toluene metabolite) at about 0.9 mg/min, caused excitation of the somatosensory evoked potential (SEP) and EEG of Fischer 344 rats. SEP excitation was characterized by a large increase in a positive waveform at about 20-50 msec. Prolonged exposure to either compound caused numerous oscillations to appear from 20 msec to the end of the recording (150 msec). Both substances induced an increase in EEG beta activity and caused a large increase in activity at 5 Hz. Toluene exposed rats were lightly anesthetized, while o-cresol rats were conscious but hyperreactive. If exposure was continued, both sets of rats had involuntary muscle movements and tremors. Benzoic acid and hippuric acid, also metabolites of toluene, were similarly tested. Neither caused neuroexcitation (about 2.4 mg/min IV, 144 mg total dose). It was concluded, therefore, that metabolically derived cresols are plausible candidates for the neuroexcitatory properties of toluene. PMID:2818714

Mattsson, J L; Albee, R R; Gorzinski, S J

288

Linking Toluene Degradation with Specific Microbial Populations in Soil  

PubMed Central

Phospholipid fatty acid (PLFA) analysis of a soil microbial community was coupled with 13C isotope tracer analysis to measure the community’s response to addition of 35 ?g of [13C]toluene ml of soil solution?1. After 119 h of incubation with toluene, 96% of the incorporated 13C was detected in only 16 of the total 59 PLFAs (27%) extracted from the soil. Of the total 13C-enriched PLFAs, 85% were identical to the PLFAs contained in a toluene-metabolizing bacterium isolated from the same soil. In contrast, the majority of the soil PLFAs (91%) became labeled when the same soil was incubated with [13C]glucose. Our study showed that coupling 13C tracer analysis with PLFA analysis is an effective technique for distinguishing a specific microbial population involved in metabolism of a labeled substrate in complex environments such as soil.

Hanson, Jessica R.; Macalady, Jennifer L.; Harris, David; Scow, Kate M.

1999-01-01

289

Incineration of toluene and chlorobenzene in a laboratory incinerator  

SciTech Connect

This paper reports results on incineration of toluene and chlorobenzene in a small laboratory incinerator. The incinerator temperature, excess air ratio and mean residence time were varied to simulate both complete and incomplete combustion conditions. The flue gas was monitored on line using Fourier transform infrared (FTIR) spectroscopy coupling with a heated long path cell (LPC). Methane, toluene, benzene, chlorobenzene, hydrogen chloride and carbon monoxide in the flue gas were simultaneously analyzed. Experimental results indicate that benzene is a major product of incomplete combustion (PIC), besides carbon monoxide, in the incineration of toluene and chlorobenzene and is very sensitive to the combustion conditions. This suggests that benzene is a target analyte to be monitored in full-scale incinerators.

Mao, Zhuoxiong; McIntosh, M.J.; Demirgian, J.C.

1992-12-31

290

Incineration of toluene and chlorobenzene in a laboratory incinerator  

SciTech Connect

This paper reports results on incineration of toluene and chlorobenzene in a small laboratory incinerator. The incinerator temperature, excess air ratio and mean residence time were varied to simulate both complete and incomplete combustion conditions. The flue gas was monitored on line using Fourier transform infrared (FTIR) spectroscopy coupling with a heated long path cell (LPC). Methane, toluene, benzene, chlorobenzene, hydrogen chloride and carbon monoxide in the flue gas were simultaneously analyzed. Experimental results indicate that benzene is a major product of incomplete combustion (PIC), besides carbon monoxide, in the incineration of toluene and chlorobenzene and is very sensitive to the combustion conditions. This suggests that benzene is a target analyte to be monitored in full-scale incinerators.

Mao, Zhuoxiong; McIntosh, M.J.; Demirgian, J.C.

1992-01-01

291

Incineration of toluene and chlorobenzene in a laboratory incinerator  

SciTech Connect

This paper reports experimental results on the incineration of toluene and chlorobenzene in a small laboratory incinerator. Temperature of the incinerator, excess air ratio and mean residence time were varied to simulate both complete and incomplete combustion conditions. The flue gas was monitored on line using Fourier transform infrared (FTIR) spectroscopy coupling with a heated long path cell (LPC). Methane, toluene, benzene, chlorobenzene, hydrogen chloride and carbon monoxide in the flue gas were simultaneously analyzed. Experimental results indicate that benzene is a major product of incomplete combustion (PIC) besides carbon monoxide in the incineration of toluene and chlorobenzene, and is very sensitive to combustion conditions. This suggests that benzene is a target analyle to be monitored in full-scale incinerators.

Mao, Z.; Mcintosh, M.J.; Demirgian, J.C.

1992-01-01

292

Mass Spectrometry Study of OH-initiated Photooxidation of Toluene  

NASA Astrophysics Data System (ADS)

The composition of products formed from photooxidation of the aromatic hydrocarbon toluene was investigated. The OH-initiated photooxidation experiments were conducted by irradiating toluene/CH3ONO/NO/air mixtures in a smog chamber, the gaseous products were detected under the supersonic beam conditions by utilizing vacuum ultraviolet photoionization mass spectrometer using synchrotron radiation in real-time. And an aerosol time-of-flight mass spectrometer was used to provide on-line measurements of the individual secondary organic aerosol particle resulting from irradiating toluene. The experimental results demonstrated that there were some differences between the gaseous products and that of particle-phase, the products of glyoxal, 2-hydroxyl-3-oxo-butanal, nitrotoluene, and methyl-nitrophenol only existed in the particle-phase. However, furane, methylglyoxal, 2-methylfurane, benzaldehyde, cresol, and benzoic acid were the predominant photooxidation products in both the gas phase and particle phase.

Huang, Ming-qiang; Zhang, Wei-jun; Wang, Zhen-ya; Fang, Li; Kong, Rui-hong; Shan, Xiao-bin; Liu, Fu-yi; Sheng, Liu-si

2011-12-01

293

Silica encapsulation of toluene soluble quantum dots with high photostability.  

PubMed

We report the silica encapsulation of toluene soluble single quantum dots (QDs) with various silica layer thicknesses. The photoluminescence of silica-encapsulated QD showed a blue shift as the silica layer increased. Although the measured decay lifetime and the quantum yields of the silica-encapsulated QDs decreased as the SiO2 layer increased, the silica-encapsulated QDs showed good photostability for certain silica layer thicknesses. Furthermore, photoblinking, the characteristic optical property of single QD, did not change after silica encapsulation. Silica encapsulation of toluene soluble QDs offers great potential for advanced optical applications. PMID:23375808

Isnaeni; Jin, Li-Hua; Cho, Yong-Hoon

2013-01-12

294

Selective toluene disproportionation over pore size controlled MFI zeolite  

SciTech Connect

Selective disproportionate of toluene to p-xylene was studied over modified MFI aluminosilicate. The relationship between extent of silica deposition and para selectivity was established. The effect of reaction parameters such as temperature and weight hourly space velocity (WHSV) on para selectivity was considered. Kinetics of reaction in the temperature range 723--773 K was carried out. The estimated activation energy value is lower than reported for toluene disproportionation in the literature. This has been explained on the basis of enhanced intracrystalline diffusion in the modified zeolite.

Das, J.; Bhat, Y.S.; Halgeri, A.B. (Indian Petrochemicals Corp. Ltd., Gujarat (India). Research Centre)

1994-02-01

295

Multiplexed detection of xylene and trichloroethylene in water by photonic crystal absorption spectroscopy.  

PubMed

We experimentally demonstrate simultaneous selective detection of xylene and trichloroethylene (TCE) using multiplexed photonic crystal waveguides (PCWs) by near-infrared optical absorption spectroscopy on a chip. Based on the slow light effect of photonic crystal structure, the sensitivity of our device is enhanced to 1 ppb (v/v) for xylene and 10 ppb (v/v) for TCE in water. Multiplexing is enabled by multimode interference power splitters and Y-combiners that integrate multiple PCWs on a silicon chip in a silicon-on-insulator platform. PMID:24081056

Lai, Wei-Cheng; Chakravarty, Swapnajit; Zou, Yi; Chen, Ray T

2013-10-01

296

Trichloroethylene--a review of the literature from a health effects perspective.  

PubMed

This report reviews the literature on the impact of exposure to trichloroethylene (TCE) on human health. Special emphasis is given to the health effects reported in excess of national norms by participants in the TCE Subregistry of the Volatile Organic Compounds Registry of the National Exposure Registries--persons with documented exposure to TCE through drinking and use of contaminated water. The health effects reported in excess by some or all of the sex and age groups studied were speech and hearing impairments, effects of stroke, liver problems, anemia and other blood disorders, diabetes, kidney disease, urinary tract disorders, and skin rashes. PMID:7482570

Gist, G L; Burg, J R

297

Microbial degradation of trichloroethylene in the rhizosphere: potential application to biological remediation of waste sites.  

PubMed Central

The possibility that vegetation may be used to actively promote microbial restoration of chemically contaminated soils was tested by using rhizosphere and nonvegetated soils collected from a trichloroethylene (TCE)-contaminated field site. Biomass determinations, disappearance of TCE from the headspace of spiked soil slurries, and mineralization of [14C]TCE to 14CO2 all showed that microbial activity is greater in rhizosphere soils and that TCE degradation occurs faster in the rhizosphere than in the edaphosphere. Thus, vegetation may be an important variable in the biological restoration of surface and near-surface soils.

Walton, B T; Anderson, T A

1990-01-01

298

Comparison of isopropyl alcohol and trichloroethylene in removing solder flux: Topical report  

SciTech Connect

This work evaluated a nontoxic solvent for its ability to remove solder flux as compared to trichloroethylene solvent. Isopropyl alcohol was evaluated for its cleaning efficiency for solder flux removal using a high pressure spray process (minimum spray pressure of 80 psig). Cleanliness levels were measured by the Meseran Surface Analyzer. Test samples also underwent gas chromatograph/mass spectrometer Analysis and were visually inspected under a longwave ultraviolet lamp. Detailed analyses of flux removal by the two solvents were made as related to solder flux types, solder flux diluted by 50% with isopropyl alcohol, and solder process conditions. 2 refs., 2 figs., 12 tabs.

Benkovich, M.G.

1988-01-01

299

SYNCHROTRON X-RAY MICROTOMOGRAPHY, ELECTRON PROBE MICROANALYSIS, AND NMR OF TOLUENE WASTE IN CEMENT.  

SciTech Connect

Synchrotron X-ray microtomography shows vesicular structures for toluene/cement mixtures, prepared with 1.22 to 3.58 wt% toluene. Three-dimensional imaging of the cured samples shows spherical vesicles, with diameters ranging from 20 to 250 {micro}m; a search with EPMA for vesicles in the range of 1-20 {micro}m proved negative. However, the total vesicle volume, as computed from the microtomography images, accounts for less than 10% of initial toluene. Since the cements were cured in sealed bottles, the larger portion of toluene must be dispersed within the cement matrix. Evidence for toluene in the cement matrix comes from {sup 29}Si MAS NMR spectroscopy, which shows a reduction in chain silicates with added toluene. Also, {sup 2}H NMR of d{sub 8}-toluene/cement samples shows high mobility for all, toluene and thus no toluene/cement binding. A model that accounts for all observations follows: For loadings below about 3 wt%, most toluene is dispersed in the cement matrix, with a small fraction of the initial toluene phase separating from the cement paste and forming vesicular structures that are preserved in the cured cement. Furthermore, at loadings above 3 wt%, the abundance of vesicles formed during toluene/cement paste mixing leads to macroscopic phase separation (most toluene floats to the surface of the cement paste).

BUTLER,L.G.

1999-07-22

300

Shape selective toluene methylation over chromia pillared montmorillonites  

Microsoft Academic Search

Methylation of toluene is done on pillared clays. Effect of mixed pillaring on the catalytic activity and selectivity is studied. Pillaring improves the thermal stability and porosity, which makes clays suitable for high temperature, shape selective xylene preparation without higher substitution, and low deactivation. Pillared systems are found to be regenerable up to four cycles. The enhanced structural and textural

N. N. Binitha; S. Sugunan

2008-01-01

301

Pressure Dependence of the Ultrasonic Absorption in Toluene and Hexane.  

National Technical Information Service (NTIS)

Ultrasonic absorption and sound speed have been measured in toluene and n-hexane in the pressure range 1-10,000 kg/sq cm at 30C. In these Kneser-type liquids, for which the absorption may be attributed to thermal relaxational processes as well as to the d...

J. Allegra S. Hawley G. Holton

1970-01-01

302

Metabolism of benzene, toluene, and xylene hydrocarbons in soil  

SciTech Connect

Enrichment cultures obtained from soil exposed to benzene, toluene, and xylene (BTX) mineralized benzene and toluene but cometabolized only xylene isomers, forming polymeric residues. This observation prompted the authors to investigate the metabolism of {sup 14}C-labeled BTX hydrocarbons in soil, either individually or as mixtures. BTX-supplemented soil was incubated aerobically for up to 4 weeks in a sealed system that automatically replenished any O{sub 2} consumed. The decrease in solvent vapors and the production of {sup 14}CO{sub 2} were monitored. At the conclusion of each experiment, {sup 14}C distribution in solvent-extractable polymers, biomass, and humic material was determined, obtaining {sup 14}C mass balances of 85 to 98%. BTX compounds were extensively mineralized in soil, regardless of whether they were presented singly or in combinations. No evidence was obtained for the formation of solvent-extractable polymers from xylenes in soil, but {sup 14}C distribution in biomass and humus was unusual for all BTX compounds and especially for toluene and the xylenes. The results suggest that catechol intermediates of BTX degradation are preferentially polymerized into the soil humus and that the methyl substituents of the catechols derived from toluene and especially from xylenes enhance this incorporation. In contrast to inhibitory residues formed from xylene cometabolism in culture, the humus-incorporated xylene residues showed no significant toxicity in the Microtox assay.

Tsao, C.W.; Song, H.G.; Bartha, R. [Rutgers--the State Univ., New Brunswick, NJ (United States)

1998-12-01

303

PHOSPHOLIPIDS OF FIVE PSEUDOMONAD ARCHETYPES FOR DIFFERENT TOLUENE DEGRADATION PATHWAYS  

EPA Science Inventory

Liquid chromatography/electrospray ionization/mass spectrometry (LC/ESI/MS) was used to determine phospholipid profiles for five reference pseudomonad strains harboring distinct toluene catabolic pathways: Pseudomonas putida mt-2, Pseudomonas putida F1, Burkholderia cepacia G4, B...

304

Carbon Isotope Fractionation of Benzene and Toluene by Progressive Evaporation  

NASA Astrophysics Data System (ADS)

Evaporation experiments were performed to investigate carbon isotope fractionation of benzene and toluene during progressive evaporation at room temperature. Considerable carbon isotope fractionation occurred during evaporative enrichment of benzene and toluene. Carbon isotope compositions of residual compounds increased exponentially with increasing evaporation. This result was compatible with the direction of isotopic changes associated with both microbial degradation and natural evaporation previously observed in oil fields, but was not consistent with previous equilibrium volatilization findings. Although the enrichment factors obtained from non-equilibrium evaporation were much smaller than those from microbial degradation, our data indicated that carbon isotope fractionation of benzene and toluene caused by microbial degradation can be complicated by kinetic evaporation effects if both processes occur together in unsaturated zones. However, in the natural environment, carbon isotope fractionation of BTEXs by evaporation can be virtually overwhelmed by microbial degradation because enrichment factors of BTEXs are much lower in non- equilibrium evaporation than in microbial degradation. Consequently, our data are fundamental for evaluating the carbon isotope fractionation of benzene and toluene by evaporation and for tracking their fate and transport mechanisms in subsurface environments.

Lee, K.; Han, S.; Shin, W.

2008-12-01

305

NUMERICAL MODEL OF THE MIGRATION OF TOLUENE IN POROUS MEDIA  

Microsoft Academic Search

A Volatile Organic Compound (VOC) model describing migration of toluene concentration in subsurface system of porous media was developed. To investigate pollutant transport of nonaqueous phase liquids (NAPL) for VOC, requires a solution of multiphase fluid flow, heat flow and pollutant transport in a deforming porous media. The nonlinear saturation and relative permeability functions were incorporated into Galerkin finite element

Zainab Mohamed Yusof; Norhan Abd

306

Metabolism of Benzene, Toluene, and Xylene Hydrocarbons in Soil†  

PubMed Central

Enrichment cultures obtained from soil exposed to benzene, toluene, and xylene (BTX) mineralized benzene and toluene but cometabolized only xylene isomers, forming polymeric residues. This observation prompted us to investigate the metabolism of 14C-labeled BTX hydrocarbons in soil, either individually or as mixtures. BTX-supplemented soil was incubated aerobically for up to 4 weeks in a sealed system that automatically replenished any O2 consumed. The decrease in solvent vapors and the production of 14CO2 were monitored. At the conclusion of each experiment, 14C distribution in solvent-extractable polymers, biomass, and humic material was determined, obtaining 14C mass balances of 85 to 98%. BTX compounds were extensively mineralized in soil, regardless of whether they were presented singly or in combinations. No evidence was obtained for the formation of solvent-extractable polymers from xylenes in soil, but 14C distribution in biomass (5 to 10%) and humus (12 to 32%) was unusual for all BTX compounds and especially for toluene and the xylenes. The results suggest that catechol intermediates of BTX degradation are preferentially polymerized into the soil humus and that the methyl substituents of the catechols derived from toluene and especially from xylenes enhance this incorporation. In contrast to inhibitory residues formed from xylene cometabolism in culture, the humus-incorporated xylene residues showed no significant toxicity in the Microtox assay.

Tsao, C.-W.; Song, H.-G.; Bartha, R.

1998-01-01

307

Electrocardiographic effects of toluene in the anesthetized rat.  

PubMed

The influence of inhalation of near lethal quantities of toluene on some ECG parameters, as well as the possible cardiac sensitizing effect of the solvent, were determined in chloralose-anesthetized rats. These actions were compared with those of its close analogue benzene. Both solvents produced tachycardia; toluene increased the duration of QRS and specially PR, while benzene decreased P wave duration. No other systematic changes in ECG morphology or evidence of arrhythmia were observed. Toluene appeared to decrease the number of ectopic beats induced by epinephrine, in contrast to benzene, which increased it markedly. These results suggest that toluene administered by inhalation up to near lethal doses is devoid of untoward ECG effect in the chloralose-anesthetized rat, its only action being a decrease in intraventricular and particularly AV conduction. It does not share the myocardial sensitizing properties of benzene and in fact appears to elicit some protection from the arrhythmogenic effects of epinephrine, although no definite conclusions as to this action can be derived due to limitations in the experimental model used. PMID:3963933

Vidrio, H; Magos, G A; Lorenzana-Jimenez, M

1986-01-01

308

Incineration of toluene and chlorobenzene in a laboratory incinerator  

Microsoft Academic Search

This paper reports experimental results on the incineration of toluene and chlorobenzene in a small laboratory incinerator. Temperature of the incinerator, excess air ratio and mean residence time were varied to simulate both complete and incomplete combustion conditions. The flue gas was monitored on line using Fourier transform infrared (FTIR) spectroscopy coupling with a heated long path cell (LPC). Methane,

Z. Mao; M. J. Mcintosh; J. C. Demirgian

1992-01-01

309

Instrument for benzene and toluene emission measurements of glycol regenerators  

NASA Astrophysics Data System (ADS)

We introduce an in-field and in-explosive atmosphere useable instrument, which can measure the benzene and toluene concentration in two gas and two glycol samples produced by natural gas dehydration units. It is a two-phase, on-line gas chromatograph with a photoacoustic spectroscopy based detector. The time resolution is 10 min per cycle and the minimum detectable concentrations are 2 mg m?3 for benzene, 3 mg m?3 for toluene in natural gas, and 5 g m?3 for benzene and 6 g m?3 for toluene in glycol. Test measurements were carried out at a dehydration plant belonging to MOL Hungarian Oil and Gas Company. Benzene and toluene emissions of gas dehydration unit are calculated from the measured values based on mass balance of a glycol regenerator. The relationship between the outdoor temperature and the measured concentration was observed which is caused by temperature-dependent operation of the whole dehydration unit. Emission decreases with increase of outdoor temperature.

Hanyecz, Veronika; Mohácsi, Árpád; Puskás, Sándor; Vágó, Árpád; Szabó, Gábor

2013-11-01

310

Fenton-like initiation of a toluene transformation mechanism  

EPA Science Inventory

In Fenton-driven oxidation treatment systems, reaction intermediates derived from parent compounds can play a significant role in the overall treatment process. Fenton-like reactions in the presence of toluene or benzene, involved a transformation mechanism that was highly effici...

311

Inhibition of gap junction currents by the abused solvent toluene  

Microsoft Academic Search

Abused inhalants are a large class of compounds that are inhaled for their intoxicating and mood altering effects. They include chemicals with known therapeutic uses such as anesthetic gases as well as volatile organic solvents like toluene that are found in paint thinners and adhesives. Because of their widespread commercial use and availability, inhalants are often among the first drugs

Angelo M. Del Re; John J. Woodward

2005-01-01

312

Toluene Recycle in the Synthesis of TATB. Progress Report, October--December 1975.  

National Technical Information Service (NTIS)

Laboratory and pilot-plant aminations of trichlorotrinitrobenzene have shown that the toluene reaction solvent can be recycled at least once without purification and without significantly degrading the TATB product. Subsequent recycles of the toluene resu...

V. H. Evans W. T. Quinlin C. L. Schaffer Z. L. Estes

1975-01-01

313

Cation transport in gaseous, critical, and liquid benzene and toluene  

NASA Astrophysics Data System (ADS)

The mobilities ?+ of cations in the fluids of benzene and toluene are 200-3000 fold lower than those of electrons. However, the variations of the cation mobilities with density and temperature are qualitatively similar to those of electrons, to an unexpected degree. In the liquid phase under its vapor pressure at T/Tc<0.8 the cation mobility in benzene obeys Walden's rule (?+~?-x, x=1.0), but in toluene it does not (x=1.1). The ratio of the diffusion coefficients (cation/solvent molecule) is equal to about 0.25 in toluene and 0.50 in benzene. Near the critical point there is a slight maximum in ?+. The maximum is more marked in the density normalized mobility ?+n; it occurs at n/nc=2.0 in benzene and 1.6 in toluene. The mobilities in the critical fluids are 2.76×10-3 and 2.50×10-3 cm2/V s in benzene and toluene, respectively. In the low density gases the ion scattering cross sections, taken to have the form ?v=A? v-?, display ?=1.4 for benzene and 1.5 for toluene. The cross sections, appropriately averaged over the Maxwellian distribution of velocities, have magnitudes similar to those expected from scattering by the r-4 polarization potential, but have a greater than expected value of ?. The average ion scattering cross sections are about eightfold greater than the corresponding electron scattering cross sections. The value of ?+n in the coexistence vapor is 6.3×1018 molecule/cm V s in benzene up to n/nc=1.0, and is 6.0×1018 in toluene up to n/nc=0.15. At higher densities in the latter ?+n decreases gently, reaching (?+n)min=4.4×1018 at n/nc=0.9. The temperature coefficient of ?+ at constant n increases with n up to nc, near the coexistence curve. The increased temperature coefficient is attributed to clustering, but the clusters are small.

Huang, Sam S.-S.; Freeman, Gordon R.

1980-02-01

314

Final amended report of the safety assessment of toluene-2,5-diamine, toluene-2,5-diamine sulfate, and toluene-3,4-diamine as used in cosmetics.  

PubMed

Toluene-2,5-diamine, toluene-2,5-diamine sulfate, and toluene-3,4-diamine are diaminotoluenes used as colorants in permanent hair dyes and tints. Toluene-2,5-diamine is used in 79 products at concentrations up to 3%; toluene-2,5-diamine sulfate is used in 168 products at concentrations up to 4%. Toluene-3,4-diamine does not appear to be in current use. Previously, the Cosmetic Ingredient Review Expert Panel determined that all 3 ingredients were safe for use as hair dyes. New data suggest that differences in toxicity, especially with respect to carcinogenicity, may exist as a function of placement of amine groups around the benzene ring. The Expert Panel concluded that toluene-2,5-diamine and toluene-2,5-diamine sulfate and are safe as hair dye ingredients in the present practices of use and concentrations but that there are insufficient data supporting the safety of toluene-3,4-diamine. PMID:20448268

Burnett, Christina L; Bergfeld, Wilma F; Belsito, Donald V; Klaassen, Curtis D; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Alan Andersen, F

2010-05-01

315

A kinetic model for the oxidation of toluene near 1200 K  

Microsoft Academic Search

An improved kinetic model for the high-temperature oxidation of toluene has been developed using previously established reaction mechanisms for benzene and toluene. The model is compared to benzene and toluene flow reactor experiments near 1100 and 1200 K, respectively. Fuel decay rates and many intermediate species profiles are reproduced successfully for both lean and rich equivalence ratios. A linear sensitivity

J. L. Emdee; K. Brezinsky; I. Glassman

1992-01-01

316

40 CFR 721.1850 - Toluene sulfonamide bis-phe-nol A epoxy adduct.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Toluene sulfonamide bis-phe-nol A epoxy adduct. 721...Substances § 721.1850 Toluene sulfonamide bis-phe-nol A epoxy adduct. ...substance identified generically as toluene sulfonamide bisphenol A epoxy adduct (PMN...

2010-07-01

317

40 CFR 721.1850 - Toluene sulfonamide bis-phe-nol A epoxy adduct.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Toluene sulfonamide bis-phe-nol A epoxy adduct. 721...Substances § 721.1850 Toluene sulfonamide bis-phe-nol A epoxy adduct. ...substance identified generically as toluene sulfonamide bisphenol A epoxy adduct (PMN...

2009-07-01

318

Acute Toluene Exposure and Rat Visual Function in Proportion to Momentary Brain Concentration  

Microsoft Academic Search

Acute exposure to toluene was assessed in two experiments to determine the relationship between brain toluene concentration and changes in neurophysiological function. The concentration of toluene in brain tissue at the time of assessment was estimated using a physiologically based pharmacokinetic model. Brain neurophysiological function was measured using pattern-elicited visual evoked potentials (VEP) recorded from electrodes located over visual cortex

William K. Boyes; Mark Bercegeay; Quentin Todd Krantz; Elaina M. Kenyon; Ambuja S. Bale; Timothy J. Shafer; Philip J. Bushnell; Vernon A. Benignus

2007-01-01

319

Effects of Toluene on Microbially-Mediated Processes Involved in the Soil Nitrogen Cycle  

Microsoft Academic Search

The effects of toluene on indigenous microbial populations involved in the soil nitrogen cycle were examined. Ammonia oxidation potential (AOP) and nitrite oxidation potential (NOP) were both reduced after incubation with high toluene concentrations for 45 days, with the former activity showing greater sensitivity. KCl-extractable ammonium (NH 4 + ext) levels increased dramatically in soil exposed to high toluene levels,

M. E. Fuller; K. M. Scow

1996-01-01

320

Occupational exposure limits based on biological monitoring: the Japan Society for Occupational Health  

Microsoft Academic Search

The Japan Society for Occupational Health started to recommend an occupational exposure limit based on biological monitoring\\u000a (OEL-B) in 1993. Up to 1998, OEL-Bs for mercury, lead, hexane and 3,3?-dichloro-4,4?-diaminodiphenylmethane had been adopted\\u000a and those for 17 chemical substances (arsenic, cadmium, chromium, nickel, acetone, methanol, benzene, toluene, xylene, styrene,\\u000a tetrachloroethylene, trichloroethylene, N,N-dimethylacetoamide, N,N-dimethylformamide,carbon disulfide, carbon monoxide, and organophospate insecticides) are

K. Omae; T. Takebayashi; H. Sakurai

1999-01-01

321

MID-FREQUENCY HEARING LOSS IN RATS FOLLOWING INHALATION EXPOSURE TO TRICHLOROETHYLENE: EVIDENCE FROM REFLEX MODIFICATION AUDIOMETRY  

EPA Science Inventory

The present experiments were undertaken in order to characterize the hearing loss associated with 1,1,2-trichloroethylene (TCE) exposure. dult male LE rats were exposed to TCE via inhalation (whole body) for 6hr/day for 5 days. he concentration-effect function (0-4000 ppm) was de...

322

Plasma-assisted decomposition of methanol and trichloroethylene in atmospheric pressure air streams by electrical discharge processing  

SciTech Connect

Experiments are presented on the plasma-assisted decomposition of dilute concentrations of methanol and trichloroethylene in atmospheric pressure air streams by electrical discharge processing. This investigation used two types of discharge reactors, a dielectric-barrier and a pulsed corona discharge reactor, to study the effects of gas temperature and electrical energy input on the decomposition chemistry and byproduct formation. Our experimental data on both methanol and trichloroethylene show that, under identical gas conditions, the type of electrical discharge reactor does not affect the energy requirements for decomposition or byproduct formation. Our experiments on methanol show that discharge processing converts methanol to CO{sub {ital x}} with an energy yield that increases with temperature. In contrast to the results from methanol, CO{sub {ital x}} is only a minor product in the decomposition of trichloroethylene. In addition, higher temperatures decrease the energy yield for trichloroethylene. This effect may be due to increased competition from decomposition of the byproducts dichloroacetyl chloride and phosgene. In all cases plasma processing using an electrical discharge device produces CO preferentially over CO{sub 2}.

Hsiao, M.C.; Merritt, B.T.; Penetrante, B.M.; Vogtlin, G.E.; Wallman, P.H. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)

1995-09-01

323

USE OF CARBON STABLE ISOTOPE FOR THE DECHLORINATION OF TRICHLOROETHYLENE ON GRANULAR-GRAPHITE PACKED ELECTRODES (PRESENTATION)  

EPA Science Inventory

Trichloroethylene (TCE) is widely used as a solvent in metal processing and electronic manufacturing industries, but waste and spilled TCE often results in blocks of non-aqueous liquid in vadose and saturated zones which become continuous contamination sources for groundwater. El...

324

Evaluation of Methanotrophic Bacteria during Injection of Gaseous Nutrients for In Situ Trichloroethylene Bioremediation in a Sanitary Landfill  

Microsoft Academic Search

Methanotrophic bacterial populations were quantified in an aquifer that was amended with air (oxygen), methane, triethyl-phosphate, and nitrous oxide to evaluate their effectiveness to stimulate aerobic bioremediation of vinyl chloride (VC), dichloroethylene, and trichloroethylene (TCE). Contaminants in groundwater resulted from leachate originating from a nearby landfill. Groundwater samples were taken during gas injection and analyzed for changes in bacterial populations.

Brigmon

1999-01-01

325

Nonadditive Developmental Toxicity in Mixtures of Trichloroethylene, Di(2-ethylhexyl) Phthalate, and Heptachlor in a 5 × 5 × 5 Design  

Microsoft Academic Search

Nonadditive Developmental Toxicity in Mixtures of Trichloroethylene, Di(2-ethylhexyl) Phthalate, and Heptachlor in a 5 × 5 × 5 Design. Narotsky, M. G., Weller, E. A., Chinchilli V. M., and Kavlock, R. J. (1995). Fundam. Appl. Toxicol. 27, 203-216.In order to identify nonadditive effects on development, three compounds were combined using five dosages of each agent (a 5 × 5 ×

Michael G. Narotsky; Edie A. Weller; Vernon M. Chinchilli; Robert J. Kavlock

1995-01-01

326

Vapor–liquid equilibrium of binary mixtures of trichloroethylene with 1-pentanol, 2-methyl-1-butanol and 3-methyl-1-butanol at 100 kPa  

Microsoft Academic Search

Isobaric vapor–liquid equilibria (VLE) have been obtained for the systems trichloroethylene+1-pentanol, trichloroethylene+2-methyl-1-butanol and trichloroethylene+3-methyl-1-butanol at 100 kPa using a dynamic still. The experimental error in temperature is ±0.1 K, in pressure ±0.1 kPa, and in the liquid and vapor mole fraction ±0.001. The three systems satisfy the point-to-point thermodynamic consistency test. All the systems show positive deviations from ideality. The

Ana Dejoz; Vicenta González-Alfaro; Francisco J Llopis; Pablo J Miguel; M. Isabel Vázquez

1999-01-01

327

Methyl-substitution of benzene and toluene in preparations of human bone marrow  

SciTech Connect

The metabolism of benzene and toluene was investigated in preparations of human bone marrow incubated with S-adenosyl-L-methionine. Benzene undergoes a methyl-substitution reaction to yield toluene as a metabolite. Furthermore, toluene undergoes methyl-substitution in preparations of human bone marrow incubated with S-adenosyl-L-methionine to yield o-xylene, m-xylene, and p-xylene. Metabolites were detected by gas chromatography and mass spectroscopy. No metabolism of either benzene or toluene was detected when a boiled bone marrow preparation was used in the incubation, demonstrating the enzymatic nature of the S-adenosyl-L-methionine dependent methylation of both benzene and toluene.

Flesher, J.W.; Myers, S.R. (Univ. of Kentucky, Lexington (USA))

1991-01-01

328

Phenol- and toluene-degrading microbial populations from an aquifer in which successful trichloroethene cometabolism occurred  

SciTech Connect

The use of phenol or toluene to stimulate cometabolism of trichloroethene (TCE) has become an attractive approach for attempting in situ remediation of TCE. This study characterized the phenol and toluene degrading population that grew in response to toluene, phenol, and TCE additions to the Moffett Field aquifer. The objectives were to evaluate conditions for improved recovery of indigenous populations of toluene and phenol degraders; elucidation of major characteristics of the isolate collection; comparison of the rates of toluene use and TCE cometabolism among the more common aquifer strains. 25 refs., 5 figs., 4 tabs.

Fries, M.R.; Forney, L.J.; Tiedje, J.M. [Michigan State Univ., East Lansing, MI (United States)

1997-04-01

329

Synergistic effects of non-thermal plasma-assisted catalyst and ultrasound on toluene removal.  

PubMed

A wire-mesh catalyst coated by La0.8Sr0.2MnO3 was combined with a dielectric barrier discharge (DBD) reactor for toluene removal at atmospheric pressure. It was found that toluene removal efficiency and carbon dioxide selectivity were enhanced in the catalytic packed-bed reactor. In addition, ozone and nitrogen monoxide from the gas effluent byproducts decreased. This is the first time that ultrasound combined with plasma has been used for toluene removal. A synergistic effect on toluene removal was observed in the plasma-assisted ultrasound system. At the same time, the system increased toluene conversion and reduced ozone emission. PMID:22893967

Sun, Yongli; Zhou, Libo; Zhang, Luhong; Sui, Hong

2012-01-01

330

Ground discarded tires remove naphthalene, toluene, and mercury from water.  

PubMed

Ground discarded tires adsorb naphthalene, toluene, and mercury ions (Hg2+) from aqueous solutions. Their sorption properties and kinetics were determined by batch equilibration techniques at 20 degrees C. The isotherms were linear for naphthalene and toluene and their sorption coefficients were about 1340 and 255 (ml/g), respectively. Sorption of the organic compounds by the ground rubber particles was relatively fast (within 30 min). However, the mercury isotherms were non-linear, and its sorption was slow as compared to the sorption of the organics. The rubber particles had a strong affinity for Hg2+. These results show that ground discarded tires are effective in removing organic compounds and Hg2+ from wastewater and other contaminated environments. In addition it would be a useful, environmentally friendly use of discarded tires (one tire per year per capita is discarded in the United States). PMID:10901240

Gunasekara, A S; Donovan, J A; Xing, B

2000-10-01

331

Linking toluene degradation with specific microbial populations in soil  

SciTech Connect

Phospholipid fatty acid (PLFA) analysis of a soil microbial community was coupled with {sup 13}C isotope tracer analysis to measure the community's response to addition of 35 {micro}g of [{sup 13}C]tolene ml of soil solution{sup {minus}1}. After 119 h of incubation with toluene, 96% of the incorporated {sup 13}C was detected in only 16 of the total 59 PLFAs (27%) extracted from the soil. Of the total {sup 13}C-enriched PLFAs, 85% were identical to the PLFAs contained in a toluene-metabolizing bacterium isolated from the same soil. In contrast, the majority of the soil PLFAs became labeled when the same soil was incubated with [{sup 13}C]glucose. Their study showed that coupling {sup 13}C tracer analysis with PLFA analysis is an effective technique for distinguishing a specific microbial population involved in metabolism of a labeled substrate in complex environments such as soil.

Hanson, J.R.; Macalady, J.L.; Harris, D.; Scow, K.M.

1999-12-01

332

Friedel–Crafts acylation of toluene catalyzed by solid superacids  

Microsoft Academic Search

Benzoylation of toluene (141mmol) with 2mmol of benzoic anhydride or benzoyl chloride was carried out in liquid phase over 0.5g of solid superacids of sulfated and supported metal oxides at 100°C for 3h. Yields of o-, m-, and p-methylbenzophenones in the distribution of 20–30% o-, 2–4% m-, and 70–80% p-isomers were 92, 48, 28, 27, 26, and 0% for the

Kazushi Arata; Hideo Nakamura; Miyuki Shouji

2000-01-01

333

A comprehensive light scattering study of the glass former toluene  

Microsoft Academic Search

We present depolarized light scattering data of the glass former toluene as obtained from tandem Fabry-Perot interferometry and Raman scattering covering a frequency range 0.5 GHz

J. Wiedersich; N. V. Surovtsev; E. Rössler

2000-01-01

334

Deaths and tumours among rotogravure printers exposed to toluene.  

PubMed Central

A cohort of 1020 rotogravure printers exposed to toluene and employed for a minimum period of three months in eight plants during 1925-85 was studied. Air levels of toluene were available since 1943 in one plant and since 1969 in most. Based on these measurements and on present concentrations of toluene in blood and subcutaneous fat, the yearly average air levels in each plant were estimated. They reached a maximum of about 450 ppm in the 1940s and 1950s but were only about 30 ppm by the mid-1980s. Exposure to benzene had occurred up to the beginning of the 1960s. Compared with regional rates, total mortality did not increase during the observation period 1952-86 (129 observed deaths v 125 expected; SMR = 1.03). There was no increase in mortality from non-malignant diseases of the lungs, nervous system, or gastrointestinal and urinary tracts. There was no overall excess of tumours 1958-85 (68 v 54, SMR = 1.26; 95% confidence interval, CI = 0.95-1.7). Among the specific cancers, only those of the respiratory tract were significantly increased (16 v 9; SMR = 1.76, CI = 1.03-2.9). Statistical significance was not attained, however, when only subjects with an exposure period of at least five years and a latency period of at least 10 years were considered. Further, there were no dose response relations with cumulated toluene dose (ppm years). There were no significant increases of tumours at other sites, including leukaemias/lymphomas/myelomas.

Svensson, B G; Nise, G; Englander, V; Attewell, R; Skerfving, S; Moller, T

1990-01-01

335

Toluene and naphthalene sorption by iron oxide\\/clay composites  

Microsoft Academic Search

This study investigates the sorption of toluene and naphthalene by a sodium bentonite (BFN), an organoclay (WS35) and by their\\u000a respective iron oxide hydrate composites Mag_BFN and Mag_S35. The organic matter content of WS35 and Mag_S35, determined by\\u000a thermogravimetry, was used to obtain their organic matter sorption coefficients, which show that they are effective sorbents\\u000a to remove organic contaminants from

Marilda M. G. R. Vianna; Jo Dweck; Frank H. Quina; Flavio M. S. Carvalho; Claudio A. O. Nascimento

2010-01-01

336

Intramolecular noncovalent interactions: Bis(toluene)chromium(0) conformers  

NASA Astrophysics Data System (ADS)

The structure of trans- and cis-conformers of bis(toluene)chromium(0) and the intramolecular interactions in them are studied by means of MP2 and density functional theory along with topological and NBO analyses. It was concluded for the first time that the locations of two hydrogen atoms of each methyl group between the phenyl ring planes in the most stable cis-conformer of bis(toluene)chromium(0) are largely determined by the stabilizing interactions of methyl C-H bonds and their hydrogen atoms with the metal atom and chromium-carbon bonds. It was concluded from the obtained data that the C-H...Cr contacts in the studied conformers should be considered as hydrogen bonds rather than agostic interactions. Contrary to the existing conception of the quantum theory of atoms in molecules, repulsive interaction is shown to occur between the pairs of hydrogen atoms of the two methyl groups in bis(toluene)chromium(0) cis-conformers rather than the stabilizing hydrogen-hydrogen interactions.

Dem'yanov, P. I.; Poleshchuk, P. M.; Gloriozov, I. P.; Vasil'Kov, A. Yu.

2010-10-01

337

Toluene nitration in irradiated nitric acid and nitrite solution  

SciTech Connect

The kinetics, mechanisms, and stable products produced for the aryl alkyl mild ortho-para director - toluene, in irradiated nitric acid and neutral nitrite solutions were investigated using ?, and pulse radiolysis. Electron pulse radiolysis was used to determine the bimolecular rate constants for the reaction of toluene with different transient species produced by irradiation. HPLC with UV detection was primarily used to assess the stable reaction products. GC-MS and LC-MS were used to confirm the results from HPLC. Free-radical nitration reaction products were found in irradiated acidic and neutral media. In acidic medium, the ring substitution and side chain substitution and oxidation produced different nitro products. In ring substitution, nitrogen oxide radicals were added mainly to hydroxyl radical-produced cyclohexadienyl radical, and in side chain substitution they were added to the carbon-centered benzyl radical produced by H-atom abstraction. In neutral nitrite toluene solution, radiolytic ring nitration products approached a statistically random distribution, suggesting a free-radical reaction involving addition of the •NO2 radical.

Gracy Elias; Bruce J. Mincher; Stephen P. Mezyk; Jim Muller; Leigh R. Martin

2011-04-01

338

Visual evoked potentials in rotogravure printers exposed to toluene.  

PubMed Central

Visual evoked potentials (VEPs) from stimulation by checkerboard pattern reversal were examined in 54 rotogravure printers exposed to toluene (all men, aged 22-64 years, duration of exposure 1-41 years). A control group consisted of 46 subjects (23 men and 23 women; aged 22-54 years). Compared with controls the exposed group showed more frequent responses with reduced reproducibility or absence of some waves, or both; the mean P1 wave latency was prolonged and mean amplitudes N1P1 and P1N2 were reduced. The VEPs were abnormal in 24% of workers. The frequency of abnormal VEPs correlated positively with the duration of exposure to toluene and also with the degree of alcohol drinking. No association was found between measurements of VEP and electroencephalogram (EEG) or electromyogram (EMG) examinations. A VEP measurement was made in 78% of the exposed workers two years after the first examination. No statistically significant difference between the two results was found. This suggests a marked stability of the observed VEP changes. These changes can be interpreted as a subclinical sign of dysfunction of the central nervous system (CNS) related to exposure to toluene and also to alcohol consumption.

Urban, P; Lukas, E

1990-01-01

339

Cost comparison of solar detoxification with conventional alternatives for the destruction of trichloroethylene  

SciTech Connect

The purpose of this analysis is to compare the cost of solar waste detoxification processes with conventional alternatives for the treatment of trichloroethylene (TCE) in air. The solar processes that were evaluated are high flux photothermal oxidation (PHOTOX), high flux thermal catalytic reforming (SOLTOX), and low flux photocatalytic oxidation (PHOCAT). The high flux processes, PHOTOX and SOLTOX, were based on dish concentrator technology. The low flux photocatalytic process was based on parabolic trough concentrating technology. The conventional alternatives are thermal oxidation, thermal catalytic oxidation, off-site carbon regeneration, and on-site solvent recovery. Analysis of the seven processes showed PHOCAT to be the most economical treatment method. PHOTOX showed slightly better economics relative to SOLTOX. Both were competitive, with the best conventional destruction process, thermal oxidation. Off-site carbon regeneration was the most expensive treatment method. 9 refs., 7 figs.

Glatzmaier, G.C.

1991-12-01

340

Byproduct identification and mechanism determination in plasma chemical decomposition of trichloroethylene  

SciTech Connect

Plasma chemical behavior of trichloroethylene (TCE) was investigated with a packed-bed ferroelectric pellet reactor and a pulsed corona reactor. Volatile byproducts were identified by gas chromatography and mass spectrometry (GC-MS), and it was shown that reactor type, TCE concentration, flow rate, background gas, and moisture affected TCE decomposition efficiency and product distribution. Byproduct distributions in nitrogen and the negative effect of oxygen and moisture on TCE decomposition efficiency show that TCE decomposition proceeds via initial elimination of chlorine and hydrogen atoms, the addition of which to TCE accelerates its decomposition. Active oxygen species like OH radical is less likely involved in the initial step of TCE decomposition in plasma. Triplet oxygen molecules ({sup 3}O{sub 2}) scavenge intermediate carbon radicals derived from TCE decomposition to give much lower yields of organic byproducts.

Futamura, Shigeru [National Inst. for Resources and Environment, Ibaraki (Japan); Yamamoto, Toshiaki [Research Triangle Inst., Research Triangle Park, NC (United States)

1997-03-01

341

Remediation of trichloroethylene in an artificial aquifer with trees: A controlled field study  

SciTech Connect

Poplar trees have been evaluated in the field for the control of contaminated groundwater movement, but to date, the fate of the contaminants has not been demonstrated. In the present study, the authors tested a hybrid poplar for the uptake and degradation of trichloroethylene (TCE). Plants were exposed to TCE-contaminated groundwater under field conditions in lined cells for three years. During the growing seasons, the trees were able to remove over 99% of the added TCE. Less than 9% of the TCE was transpired to the atmosphere during the second and third years, and examination of the tissue showed expected metabolites, but at low levels. Chloride did not significantly accumulate in the plant tissues, but chloride ion increased in the soil in amounts that approximately corresponded to TCE loss. These results demonstrate that treatment of TCE-contaminated groundwater with this poplar clone can result in efficient destruction of TCE.

Newman, L.A.; Wang, X.; Muiznieks, I.A. [Univ. of Washington, Seattle, WA (United States)] [and others

1999-07-01

342

Trichloroethylene degradation in a coupled anaerobic/aerobic reactor oxygenated using hydrogen peroxide.  

PubMed

In this work, trichloroethylene (TCE) degradation under combined anaerobic-aerobic conditions was studied in an ethanol-fed biofilm reactor oxygenated using hydrogen peroxide. The reactor was inoculated with a biomass originating from an anaerobic digestor. Granulated peat was added to the reactor as a substratum for biofilm development. Extensive characterization of reactor populations using activity tests and PCR analysis revealed the development of a mutualistic consortium, particularly methanotrophic and methanogenic microorganisms. This consortium was shown to degrade TCE by a combination of reductive and oxidative pathways. A near complete degradation of TCE at a load of 18 mg L(R)(-1) day(-1) was evidenced by a stoichiometric release of inorganic chloride. PMID:14717201

Tartakovsky, B; Manuel, M F; Guiot, S R

2003-12-15

343

Trichloroethylene adsorption by pine needle biochars produced at various pyrolysis temperatures.  

PubMed

In this study, pine needles were converted to biochar (BC) at different pyrolysis temperatures of 300, 500, and 700 °C to sorb trichloroethylene (TCE), and the changes in BC properties with each temperature were evaluated. Pyrolysis temperature showed a pronounced effect on BC properties. Decreases in molar H/C and O/C ratios resulted from removing O- and H-containing functional groups with increasing temperature, and produced high aromaticity and low polarity BCs. BCs produced at higher temperature showed greater TCE removal efficiency from water due to their high surface area, micro-porosity, and carbonized extent. The performance of various BCs for TCE removal was assessed by the Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich adsorption models, among which the Temkin and Dubinin-Radushkevich models best described TCE adsorption onto various BCs, indicating prevailing sorption mechanism as pore-filling. PMID:23838320

Ahmad, Mahtab; Lee, Sang Soo; Rajapaksha, Anushka Upamali; Vithanage, Meththika; Zhang, Ming; Cho, Ju Sik; Lee, Sung-Eun; Ok, Yong Sik

2013-06-19

344

Ozonation of trichloroethylene in acetic acid solution with soluble and solid humic acid.  

PubMed

The combined flushing and oxidation process using acetic acid and ozone has been used successfully to remove trichloroethylene (TCE) completely from contaminated soil. In this study, the effects of humic acid, a fraction of the organic matter in soil, over the performance of TCE decomposition was evaluated. TCE decomposition by ozone was enhanced by the presence of humic acid at concentrations lower than 8mgCL(-1) and then inhibited at higher concentrations. It is possible that the presence of the soluble humic acid fraction during the ozonation of TCE in acetic acid solutions produces hydroxyl radicals during the TCE ozonation which appears to be the reason for the enhanced TCE decomposition rate. Solid humic acid reduced TCE decomposition rate by acting as an ozone scavenger. Similarly, sorbed TCE reduced the amount of TCE available for decomposition by ozone in solution. PMID:18511186

Alcántara-Garduño, Martha E; Okuda, Tetsuji; Nishijima, Wataru; Okada, Mitsumasa

2008-03-30

345

Competition by aquifer materials in a bimetallic nanoparticle/persulfate system for the treatment of trichloroethylene.  

PubMed

It has been suggested in the literature that aquifer materials can compete with the target organic compounds in an activated peroxygen system. In this study, we employed a rapid treatment method using persulfate activated with bimetallic nanoparticles to investigate the competition between aquifer materials and the dissolved phase of a target organic compound. The concentration of dissolved trichloroethylene (TCE) remaining after using the activated persulfate system was two- to three-fold higher in a soil slurry batch system than in an aqueous batch system. For all five aquifer materials investigated, an increase in the mass of the aquifer solids significantly decreased the degradation of TCE. A linear relationship was observed between the mass of aquifer materials and the initial TCE degradation rate, suggesting that the organic carbon and/or aquifer material constituents (e.g., carbonates and bicarbonates) compete with the oxidation of TCE. PMID:23949733

Al-Shamsi, Mohammed Ahmad; Thomson, Neil R

2013-09-25

346

IR-Fourier spectroscopic studies of structural changes in fullerenes C60 and C70-Toluene systems  

NASA Astrophysics Data System (ADS)

The C60-toluene and C70-toluene complexes were studied by IR-Fourier spectroscopy. The complexes were obtained by crystallization from a toluene solution at room temperature. The changes in the IR spectra caused by the deformation of toluene molecules in the complexes allowed us to study the phase transitions in the fullerene-aromatic solvent systems.

Aksenova, V. V.; Nikonova, R. M.; Lad'yanov, V. I.; Mukhgalin, V. V.; Sterkhova, I. V.

2013-06-01

347

Physiologically Based Pharmacokinetic Modeling of the Lactating Rat and Nursing Pup: A Multiroute Exposure Model for Trichloroethylene and its Metabolite, Trichloroacetic Acid.  

National Technical Information Service (NTIS)

A physiologically based pharmacokinetic (PB-PK) model was developed to describe trichloroethylene (TCE) kinetics in the lactating rate and nursing pup. The lactating dam was exposed to TCE either by inhalation or by ingestion in drinking water. The nursin...

D. H. Taylor H. J. Clewell J. W. Fisher M. E. Andersen T. A. Whittaker

1990-01-01

348

Protecting the Ogallala Aquifer. Recommendations for Characterization of Trichloroethylene at the Pantex Plant Burning Brounds. Final Report to the Secretary of Energy.  

National Technical Information Service (NTIS)

This report is primarily focused on efforts to characterize the extent of trichloroethylene (TCE) contamination beneath the Burning Grounds. However, this report also discusses other contamination beneath Pantex and includes four recommendations for the D...

2000-01-01

349

Photocatalytic decomposition of aqueous trichloroethylene and direct red-79 with TiO sub 2 as a function of irradiation indensity  

SciTech Connect

The degradation of aqueous trichloroethylene (TCE) to CO{sub 2} and HCl is accomplished photocatalytically by irradiated TCE solutions, which contain suspensions of anatase TiO{sub 2}, which simulated sunlight.

Magrini, K.A.; Webb, J.D.

1991-01-01

350

Suppression of Pulmonary Host Defenses and Enhanced Susceptibility to Respiratory bacterial Infection in mice Following Inhalation Exposure to Trichloroethylene and Chloroform  

EPA Science Inventory

Numerous epidemiologic studies have associated episodes of increased air pollution with increased incidence of respiratory disease, including pneumonia, croup, and bronchitis. Trichloroethylene (TCE) and chloroform are among 33 hazardous air pollutants identified by the U.S. Env...

351

Acute behavioural comparisons of toluene and ethanol in human subjects.  

PubMed Central

A comparison of toluene and ethanol (EtOH) induced changes in central nervous system (CNS) function and symptoms were evaluated in two studies, and when possible the effects of toluene were expressed in EtOH equivalent units. The toluene concentrations were 0, 75, and 150 ppm, bracketing the American Conference of Governmental Industrial Hygienists threshold limit value (ACGIH TLV) of 100 ppm. The socially relevant EtOH doses were 0.00, 0.33, and 0.66 g EtOH/kg body weight, equivalent to two and four 3.5% 12 ounce beers. Forty two paid college students were used in each study. In the first study, subjects were exposed to toluene and an odour masking agent menthol (0.078 ppm) for seven hours over three days. In the second study EtOH or a placebo was administered at 1530 across three days also in the presence of menthol. Verbal and visual short term memory (Sternberg, digit span, Benton, pattern memory), perception (pattern recognition), psychomotor skill (simple reaction time, continuous performance, symbol-digit, hand-eye coordination, finger tapping, and critical tracking), manual dexterity (one hole), mood (profile on mood scales (POMS), fatigue (fatigue checklist), and verbal ability were evaluated at 0800, 1200, and 1600. Voluntary symptoms and observations of sleep were collected daily. A 3 x 3 latin square design evaluated solvent effects simultaneously controlling for learning and dose sequence. An analysis of variance and test for trend were performed on am-pm differences reflecting an eight hour workday and on pm scores for each solvent, in which subjects were their own control Intersubject variation in absorbance was monitored in breath. A 5 to 10% decrement was considered meaningful if consistent with a linear trend at p less than 0.05. At 150 ppm toluene, losses in performance were 6.0% for digit span, 12.1% for pattern recognition (latency), 5% for pattern memory (number correct), 6.5% for one hole, and 3% for critical tracking. The number of headaches and eye irritation also increased in a dose-response manner. The greatest effect was found for an increasing number of observations of sleep. A range of 2 to 7% decrements suggest the ACGIH TLV of 100 ppm toluene may be a good estimate of the biological threshold supporting a re-evaluation of the TLV. At 0.66 g EtOH/kg body weight symptoms and performance decrements were 6.6% for digit span, 9.2% for pattern recognition, 4.0% for continuous performance, 7.9% for symbol-digit, 16.5% for finger tapping, 6.2% for critical tracking, and 5.2% for the one hole test. The EtOH equivalents at 150 ppm toluene for digit span (0.56g EtOH/kg/body weight), the latency for pattern recognition (0.66 g EtOH kg body weight), and the one hole element "move" (0.37 g EtOH kg body weight) show that the first two measures would be affected at or above the 50 mg% blood alcohol concentration. This concentration is recognised as the lowest alcohol concentration associated with increased numbers of automobile accidents. The results suggest that EtOH may be a useful acute standard to compare the effects of various industrial solvents and support investigating an association between exposure to solvents and increased risk to safety in industry.

Echeverria, D; Fine, L; Langolf, G; Schork, T; Sampaio, C

1991-01-01

352

Acute behavioural comparisons of toluene and ethanol in human subjects.  

PubMed

A comparison of toluene and ethanol (EtOH) induced changes in central nervous system (CNS) function and symptoms were evaluated in two studies, and when possible the effects of toluene were expressed in EtOH equivalent units. The toluene concentrations were 0, 75, and 150 ppm, bracketing the American Conference of Governmental Industrial Hygienists threshold limit value (ACGIH TLV) of 100 ppm. The socially relevant EtOH doses were 0.00, 0.33, and 0.66 g EtOH/kg body weight, equivalent to two and four 3.5% 12 ounce beers. Forty two paid college students were used in each study. In the first study, subjects were exposed to toluene and an odour masking agent menthol (0.078 ppm) for seven hours over three days. In the second study EtOH or a placebo was administered at 1530 across three days also in the presence of menthol. Verbal and visual short term memory (Sternberg, digit span, Benton, pattern memory), perception (pattern recognition), psychomotor skill (simple reaction time, continuous performance, symbol-digit, hand-eye coordination, finger tapping, and critical tracking), manual dexterity (one hole), mood (profile on mood scales (POMS), fatigue (fatigue checklist), and verbal ability were evaluated at 0800, 1200, and 1600. Voluntary symptoms and observations of sleep were collected daily. A 3 x 3 latin square design evaluated solvent effects simultaneously controlling for learning and dose sequence. An analysis of variance and test for trend were performed on am-pm differences reflecting an eight hour workday and on pm scores for each solvent, in which subjects were their own control Intersubject variation in absorbance was monitored in breath. A 5 to 10% decrement was considered meaningful if consistent with a linear trend at p less than 0.05. At 150 ppm toluene, losses in performance were 6.0% for digit span, 12.1% for pattern recognition (latency), 5% for pattern memory (number correct), 6.5% for one hole, and 3% for critical tracking. The number of headaches and eye irritation also increased in a dose-response manner. The greatest effect was found for an increasing number of observations of sleep. A range of 2 to 7% decrements suggest the ACGIH TLV of 100 ppm toluene may be a good estimate of the biological threshold supporting a re-evaluation of the TLV. At 0.66 g EtOH/kg body weight symptoms and performance decrements were 6.6% for digit span, 9.2% for pattern recognition, 4.0% for continuous performance, 7.9% for symbol-digit, 16.5% for finger tapping, 6.2% for critical tracking, and 5.2% for the one hole test. The EtOH equivalents at 150 ppm toluene for digit span (0.56g EtOH/kg/body weight), the latency for pattern recognition (0.66 g EtOH kg body weight), and the one hole element "move" (0.37 g EtOH kg body weight) show that the first two measures would be affected at or above the 50 mg% blood alcohol concentration. This concentration is recognised as the lowest alcohol concentration associated with increased numbers of automobile accidents. The results suggest that EtOH may be a useful acute standard to compare the effects of various industrial solvents and support investigating an association between exposure to solvents and increased risk to safety in industry. PMID:1954153

Echeverria, D; Fine, L; Langolf, G; Schork, T; Sampaio, C

1991-11-01

353

Selection of a Pseudomonas cepacia strain constitutive for the degradation of trichloroethylene  

SciTech Connect

Groundwater contamination by organic pollutants, particularly volatile organics including TCE, DCE, I,I-DCE, and vinyl chloride, is of concern throughout the industrialized world. The capability of biologically degrading such contaminants at the site of pollution should be of considerable treatment value. However, all TCE-degrading bacterial, with one exception, require the addition of an exogenous inducer substrate such as toluene, phenol, methane, isoprene, propane or 2,4-dichlorophenoxyacetic acid to induce the enzymes require for the degradation TCE. This paper describes a Tn5-induced mutant of Pseudomonas cepacia G4 (Tom-) that does not express toluene ortho-monooxygenase (TOM) but spontaneously reverts to the constitutive expression of TOM. This revertant no longer requires aromatic induction of the TOM pathway enzyme(s) in order to degrade TCE.

Shields, M.S. (Univ. of West Florida, Pensacola (United States)); Reagin, M.J. (Technical Resources Inc., Gulf Breeze, FL (United States) Environmental Protection Agency, Gulf Breeze, FL (United States))

1992-12-01

354

Protective effect of quercetin on liver damage induced by chronic toluene exposure in rats.  

PubMed

The aim of this study was to evaluate the possible protective effects of quercetin (QE) on liver injury caused by chronic toluene exposure in rats. The rats were randomly allotted into one of three experimental groups: control, toluene treated and toluene treated with QE; each group contained 10 animals. The control group received 1 ml physiologic serum, and toluene treatment was performed by inhalation of 3000 ppm toluene, for 8 h/day and 6 days/week for 12 weeks. The rats in the QE-treated groups were given QE (15 mg/kg, intraperitoneal) once a day for 12 weeks starting just after toluene exposure. Tissue samples were obtained for histopathological investigation. To date, no histopathological changes in the liver of rats after chronic toluene exposure by QE treatment have been reported. Light microscopic evaluation of liver tissue samples of toluene-exposed rats revealed enlarged sinusoids filled with blood. In addition, some of the hepatocytes showed loss of cytoplasm, and some had a hyperchromatic nucleus. QE treatment attenuated alterations in liver histology. The alpha smooth muscle actin, transforming growth factor beta-positive cells and the activity of terminal deoxynucleotidyl transferase dUTP nick end labeling in the toluene-treated group were observed to be reduced with QE treatment. The data indicate that QE attenuates toluene-induced liver injury, but further investigation is still absolutely necessary. PMID:21859773

Kanter, Mehmet

2011-08-22

355

Protective effects of quercetine on the neuronal injury in frontal cortex after chronic toluene exposure.  

PubMed

The aim of this study was designed to evaluate the possible protective effects of quercetine (QE) on the neuronal injury in the frontal cortex after chronic toluene exposure in rats. The rats were randomly allotted into one of the three experimental groups, namely, groups A (control), B (toluene treated) and C (toluene-treated with QE), where each group contains 10 animals. Control group received 1 ml of normal saline solution, and toluene treatment was performed by the inhalation of 3000 ppm toluene in an 8-h/day and 6-day/week order for 12 weeks. The rats in QE-treated group was given QE (15 mg/kg body weight) once a day intraperitoneally for 12 weeks, starting just after toluene exposure. Tissue samples were obtained for histopathological investigation. To date, no histopathological changes of neurodegeneration in the frontal cortex after chronic toluene exposure in rats by QE treatment have been reported. In this study, the morphology of neurons in the QE treatment group was well protected. Chronic toluene exposure caused severe degenerative changes, shrunken cytoplasm and extensively dark picnotic nuclei in neurons of the frontal cortex. We conclude that QE therapy causes morphologic improvement in neurodegeneration of frontal cortex after chronic toluene exposure in rats. We believe that further preclinical research into the utility of QE may indicate its usefulness as a potential treatment on neurodegeneration after chronic toluene exposure in rats. PMID:22252859

Kanter, Mehmet

2012-01-17

356

Impact of trichloroethylene contaminated groundwater discharged to the main canal and Indian River lagoon, Vero Beach, Florida  

SciTech Connect

Groundwater highly contaminated with trichloroethylene (TCE) from a leaky storage tank was detected in Vero Beach, Florida in 1978. Aware of this problem, the local and state authorities gave permission to pump out the contaminated water as a means of reducing concentrations in the aquifer. The water was air sprayed to strip the organic compounds and subsequently discharged and mixed by means of a hydraulic pump in the drainage canal. The average discharge rate of contaminated water into the canal was approximately 0.2 million gallons per day. This project was initiated to determine the spatial distribution of pollutants in the canal and river as well as rainfall and canal flow rate effects on water, sediment, and biological organisms. Prior to flushing the well, a baseline survey of trichloroethylene and other related compounds in the canal and river was performed.

Wang, T.; Lenahan, R.; Kanik, M.

1985-04-01

357

Interactions between benzene, toluene, and p-xylene (BTX) during their biodegradation  

SciTech Connect

A microbial consortium and Pseudomonas strain (PPO1) were used in studying biodegradation of benzene, toluene, and p-xylene under aerobic conditions. Studies involved removal of each compound individually as well as in mixture with the others. Both cultures exhibited a qualitatively similar behavior toward each compound. Both the pure culture and the consortium grew on benzene following Monod kinetics, on toluene following inhibitory kinetics, whereas neither could grow on p-xylene. Benzene and toluene mixtures were removed under cross-inhibitory (competitive inhibition) kinetics. In the presence of benzene and/or toluene, p-xylene was cometabolically utilized by both cultures, but was not completely mineralized. Metabolic intermediates of p-xylene accumulated in the medium and were identified. Benzene and toluene were completely mineralized. Cometabolic removal of p-xylene reduced the yields on both benzene and toluene. Except for cometabolism, kinetic constants were determined from data analysis and are compared with values published recently by other researchers.

Oh, Y.S.; Bartha, R. (Rutgers Univ., New Brunswick, NJ (United States). Dept. of Biochemistry and Microbiology); Shareefdeen, Z.; Baltzis, B.C. (New Jersey Inst. of Tech., Newark, NJ (United States). Dept. of Chemical Engineering)

1994-08-05

358

Toluene formation from coadsorbed methanethiol and benzenethiol on the Ni(III) surface  

SciTech Connect

We report our observation of interspecies carbon-carbon bond formation during the reaction of coadsorbed methanethiol and benzenethiol on the Ni(III) surface. Toluene formation has been detected between 250 and 320 K in addition to methane and benzene, the hydrogenolysis products. Increased concentrations of benzenethiolate and methanethiolate, the surface intermediates, increase the amount of toluene formed. Water formation below the toluene formation temperature decreases surface hydrogen, causing toluene yield to increase substantially compared to methane and benzene yield. Toluene increases up to a factor of 20 were observed for high coadsorbed coverages. Together, these results clearly indicate that competition between hydrogen addition and alkylation controls toluene formation. 28 refs., 3 figs.

Kane, S.M.; Gland, J.L. [Univ. of Michigan, Ann Arbor, MI (United States); Huntley, D.R. [Oak Ridge National Lab., TN (United States)

1996-04-17

359

Active site dynamics of toluene hydroxylation by cytochrome P-450  

SciTech Connect

Rat liver cytochrome P-450 hydroxylates toluene to benzyl alcohol plus o-, m-, and p-cresol. Deuterated toluenes were incubated under saturating conditions with liver microsomes from phenobarbital-pretreated rats, and product yields and ratios were measured. Stepwise deuteration of the methyl leads to stepwise decreases in the alcohol/cresol ratio without changing the cresol isomer ratios. Extensive deuterium retention in the benzyl alcohols from PhCH{sub 2}D and PhCHD{sub 2} suggests there is a large intrinsic isotope effect for benzylic hydroxylation. After replacement of the third benzylic H by D, the drop in the alcohol/cresol ratio was particularly acute, suggsting that metabolic switching from D to H within the methyl group was easier than switching from the methyl to the ring. Comparison of the alcohol/cresol ratio for PhCH{sub 3} vs PhCD{sub 3} indicated a net isotope effect of 6.9 for benzylic hydroxylation. From product yield data for PhCH{sub 3} and PhCD{sub 3}, {sup D}V for benzyl alcohol formation is only 1.92, whereas {sup D}V for total product formation is 0.67 (i.e., inverse). From competitive incubations of PhCH{sub 3}/PhCD{sub 3} mixtures {sup D}(V/K) isotope effects on benzyl alcohol formation and total product formation (3.6 and 1.23, respectively) are greatly reduced, implying strong commitment to catalysis. In contrast, {sup D}(V/K) for the alcohol/cresol ratio is 6.3, indicating that the majority of the intrinsic isotope effect is expressed through metabolic switching. Overall, these data are consistent with reversible formation of a complex between toluene and the active oxygen form of cytochrome P-450, which rearranges internally and reacts to form products faster than it dissociates back to release substrate.

Hanzlik, R.P.; Kahhiing John Ling (Univ. of Kansas, Lawrence (United States))

1990-06-22

360

Adsorption behavior of toluene on modified 1X molecular sieves.  

PubMed

In this paper, the toluene adsorption/desorption properties of modified 13X molecular sieves (M-13X) are discussed. M-13X molecular sieves were prepared by acidic and steam treatments of 13X molecular sieves. The structural parameters of M-13X were evaluated and compared with those of other molecular sieves (HY, HZSM-5, Cs7NaMOR, and a commercial 13X). The results show that the specific surface area, average pore diameter and pore volume of M-13X were 414.17 m2/g, 2.98 nm, and 0.31 mL/g, respectively. The pore size distribution of M-13X was 1.8-3.0 nm. Because of its larger Si/Al ratio (Si/Al = 6.77), the hydrophobicity of M-13X is much higher than that of 13X (Si/Al = 1.28), indicating that it is particularly well suited to toluene control applications. The saturation adsorption capacity of M-13X was 0.045 g/g for simulated toluene at a temperature of 293 K and a relative humidity of 50%. The optimal regeneration temperature of M-13X was 473 K for 120 min with a hot air flow rate of 140 L/min. Implications: The modified 13X molecular sieves (M-13X) are adsorbents with a high adsorption capacity and great hydrophobicity, suitable for the treatment of VOCs. The purpose of the present investigation is to provide a practical guide for their design. PMID:23155869

Yu, Yunfeng; Zheng, Liangwei; Wang, Jiade

2012-10-01

361

Considering pharmacokinetic and mechanistic information in cancer risk assessments for environmental contaminants: Examples with vinyl chloride and trichloroethylene  

Microsoft Academic Search

Risk assessments for vinyl chloride (VC) and trichloroethylene (TCE) are presented as examples of approaches for incorporating chemical-specific pharmacokinetic and mechanistic information into a more scientifically plausible cancer risk assessment. For VC, the evidence regarding mode of action includes direct reaction of a metabolite with DNA, resulting in DNA adducts and mistranscription, and cross-species target-tissue correspondence of a rare tumor

H. J. Clewell; P. R. Gentry; J. M. Gearhart; B. C. Allen; M. E. Andersen

1995-01-01

362

Trichloroethylene decomposition and in-situ dry sorption of Cl-products by calcium oxides prepared from hydrated limes  

Microsoft Academic Search

A comparison of CaOs produced by calcining two types of hydrated lime and calcium carbonate was made for decomposition of trichloroethylene and in-situ dry sorption of the decomposed Cl-products using a lab-scale gas flow type tubular packed bed reactor. About 20mg of CaO sample was mixed with about 2g of Al2O3 particles and packed in the reactor and allowed to

Yoshimi Gotoh; Goichi Iwata; Kyaw Choh; Mitsuhiro Kubota; Hitoki Matsuda

2011-01-01

363

The use of in vitro metabolic parameters and physiologically based pharmacokinetic (PBPK) modeling to explore the risk assessment of trichloroethylene  

Microsoft Academic Search

A physiologically based pharmacokinetic (PBPK) model has been developed for trichloroethylene (1,1,2-trichloroethene, TRI) for rat and humans, based on in vitro metabolic parameters. These were obtained using individual cytochrome P450 and glutathione S-transferase enzymes. The main enzymes involved both for rats and humans are CYP2E1 and the ?- and ?-class glutathione S-transferases. Validation experiments were performed in order to test

Erna M. Hissink; Jan J. P. Bogaards; Andreas P. Freidig; Jan N. M. Commandeur; Nico P. E. Vermeulen; Peter J. van Bladeren

2002-01-01

364

Recovery of asphalt from methylene chloride and trichloroethylene by the abson method. Final report, November 1987August 1989  

Microsoft Academic Search

The objective of the in-house study was to determine if methylene chloride (CH2Cl2) can be used to recover asphalts using the Abson method (AASHTO T 170 and ASTM D 1856), and to compare its effects on recovered binder properties to those of trichloroethylene (C2HCl3). Current nationally standardized test procedures (AASHTO and ASTM) do not allow methylene chloride in the Abson

K. D. Stuart; D. Kumari; K. T. Tran

1989-01-01

365

Evaluation of trichloroethylene degradation by E. coli transformed with dimethyl sulfide monooxygenase genes and\\/or cumene dioxygenase genes  

Microsoft Academic Search

Pseudomonas fluorescens IP01 grown on isopropylbenzene (cumene) and Acinetobacter sp. 20B grown on dimethyl sulfide (DMS) degraded up to 90% and 25% of 1.5 mg trichloroethylene (TCE)\\/l, respectively. Escherichia coli harboring the DMS monooxygenase genes from strain 20B, the cumene dioxygenase genes from strain IP01 and both oxygenase genes, degraded up to 50%, 75% and 88% of 75 mg TCE\\/l, respectively. The

Wako Takami; Msae Horinouchi; Hideaki Nojiri; Hisakazu Yamane; Toshio Omori

1999-01-01

366

Determination of dichloromethane, trichloroethylene and perchloroethylene in urine samples by headspace solid phase microextraction gas chromatography–mass spectrometry  

Microsoft Academic Search

A method for the determination of volatile chlorinated hydrocarbons, namely dichloromethane (DCM), trichloroethylene (TCE), and perchloroethylene (PCE), in urine samples was developed using headspace solid phase microextraction (HS-SPME) gas chromatography–mass spectrometry (GC–MS). HS-SPME was performed using a 75?m Carboxen-polydimethylsiloxane fiber. Factors, which affect the HS-SPME process, such as adsorption and desorption times, stirring, salting-out effect, and temperature of sampling have

Diana Poli; Paola Manini; Roberta Andreoli; Innocente Franchini; Antonio Mutti

2005-01-01

367

The effect of ionic strength and hardness of trichloroethylene-contaminated synthetic groundwater on remediation using granular activated carbon  

Microsoft Academic Search

The objective of this study is to evaluate the effect of ionic strength and hardness of trichloroethylene (TCE)-contaminated\\u000a synthetic groundwater on remediation using granular activated carbon (GAC). The TCE sorption rate onto GAC in synthetic groundwater\\u000a was observed by batch experiments and ranged from 86.2% to 100%. As the ionic strength and hardness of the synthetic groundwater\\u000a increased, the TCE

Joong-Hyeok Heo; Dal-Heui Lee; Dong-Chan Koh; Ho-Wan Chang

2007-01-01

368

Photocatalytic degradation of trichloroethylene over TiO 2 \\/SiO2 in an annulus fluidized bed reactor  

Microsoft Academic Search

The effects of superficial gas velocity (Ug), wavelength and intensity of ultraviolet (UV) light, oxygen and H2O concentration on the photocatalytic degradation of TCE (Trichloroethylene) over TiO2\\/SiO2 catalyst have been determined in an annulus fluidized bed photoreactor. The key factor in determining the performance of\\u000a the annulus fluidized bed photoreactor is found to be an optimum superficial gas velocity (Ug)

Tak-Hyoung Lim; Sang-Done Kim

2002-01-01

369

Investigation of the long-term performance of zero-valent iron for reductive dechlorination of trichloroethylene  

Microsoft Academic Search

This research investigated the long-term performance of zero-valent iron for mediating the reductive dechlorination of trichloroethylene (TCE). Over a 2-year period, rates of TCE dechlorination in columns packed with iron filings were measured in simulated groundwaters containing either 3 mM CaSOâ, 5 mM CaClâ, or 5 mM Ca(NOâ)â. At early elapsed times, TCE reaction rates were pseudo-first-order in TCE concentration

James Farrell; Mark Kason; Nicos Melitas; Tie Li

2000-01-01

370

The Equilibrium Constant for the Methylcyclohexane–Toluene System  

Microsoft Academic Search

The equilibrium constant for the methylcyclohexane–toluene system has been experimentally determined due to a lack of fit appearing in kinetic evaluations when using literature values for the equilibrium constant. The most recent literature value of Keq(T=650 K)=4.61±0.04×109 kPa3 due to J. Akyurtlu and W. E. Stewart (J. Catal.51, 101 (1978)) was redetermined to a value of Keq(T=650 K)=3.60±0.05×109 kPa3 with

T Schildhauer; E Newson; St Müller

2001-01-01

371

Conversion studies with substrate analogues of toluene in a sulfate-reducing bacterium, strain Tol2  

Microsoft Academic Search

Anaerobic toluene oxidation by the sulfate-reducing bacterium, strain Tol2 (proposed nameDesulfobacula toluolica) was specifically inhibited by benzyl alcohol when added at concentrations around 500 ?M. Benzyl alcohol added at lower,\\u000a non-inhibitory concentrations (around 5 ?M) was not oxidized by active cells pregrown on toluene, indicating that the alcohol\\u000a is not a free intermediate of toluene metabolism in the sulfate reducer.

Ralf Rabus; Friedrich Widdel

1995-01-01

372

Evaluating the NMDA-Glutamate Receptor as a Site of Action for Toluene, In Vivo  

Microsoft Academic Search

Acute exposure to toluene and other volatile organic solvents results in neurotoxicity characterized by nervous system depres- sion, cognitive and motor impairment, and alterations in visual function. In vitro, toluene disrupts the function of N-methyl-D- aspartate (NMDA)-glutamate receptors, indicating that effects on NMDA receptor function may contribute to toluene neurotoxicity. NMDA-glutamate receptors are widely present in the visual system and

Ambuja S. Bale; Meredith D. Jackson; Quentin Todd Krantz; Vernon A. Benignus; Philip J. Bushnell; Timothy J. Shafer; William K. Boyes

2007-01-01

373

Effect of ceria nanoparticles on soot inception and growth in toluene–oxygen–argon mixtures  

Microsoft Academic Search

Soot formation from the combustion of toluene (C6H5CH3) and of two concentrations of nano-sized-ceria-laden toluene was monitored using a shock tube to observe the effect of the organometallic additive on the formation of soot from its point of inception. Two concentrations of ceria, of chemical composition CeO1.63, were employed to examine the effect on soot production of toluene over the

B. Rotavera; A. Kumar; S. Seal; E. L. Petersen

2009-01-01

374

Toluene and n-heptane sorption in Matrimid ® asymmetric hollow fiber membranes  

Microsoft Academic Search

Equilibrium and transient sorption isotherms were obtained for toluene and n-heptane in both annealed and non-annealed Matrimid® asymmetric hollow fiber membranes at 35°C. Equilibrium sorption follows the dual mode model except for toluene sorption into annealed fibers above a pressure of 0.5psia. Except at the highest toluene exposure pressure, the equilibrium uptake of penetrant in annealed fibers was signigicantly less

Jong Suk Lee; Ryan T. Adams; William Madden; William J. Koros

2009-01-01

375

Diversity of Five Anaerobic Toluene-Degrading Microbial Communities Investigated Using Stable Isotope Probing  

PubMed Central

Time-series DNA-stable isotope probing (SIP) was used to identify the microbes assimilating carbon from [13C]toluene under nitrate- or sulfate-amended conditions in a range of inoculum sources, including uncontaminated and contaminated soil and wastewater treatment samples. In all, five different phylotypes were found to be responsible for toluene degradation, and these included previously identified toluene degraders as well as novel toluene-degrading microorganisms. In microcosms constructed from granular sludge and amended with nitrate, the putative toluene degraders were classified in the genus Thauera, whereas in nitrate-amended microcosms constructed from a different source (agricultural soil), microorganisms in the family Comamonadaceae (genus unclassified) were the key putative degraders. In one set of sulfate-amended microcosms (agricultural soil), the putative toluene degraders were identified as belonging to the class Clostridia (genus Desulfosporosinus), while in other sulfate-amended microcosms, the putative degraders were in the class Deltaproteobacteria, within the family Syntrophobacteraceae (digester sludge) or Desulfobulbaceae (contaminated soil) (genus unclassified for both). Partial benzylsuccinate synthase gene (bssA, the functional gene for anaerobic toluene degradation) sequences were obtained for some samples, and quantitative PCR targeting this gene, along with SIP, was further used to confirm anaerobic toluene degradation by the identified species. The study illustrates the diversity of toluene degraders across different environments and highlights the utility of ribosomal and functional gene-based SIP for linking function with identity in microbial communities.

Sun, Weimin

2012-01-01

376

Sonochemical treatment of benzene/toluene contaminated wastewater  

SciTech Connect

Studies of the destruction of benzene and toluene in water were undertaken using ultrasonic irradiation in a parallel place Near Field Acoustic Processor (NAP). This magnetostrictive system is capable of degrading both benzene and toluene in a continuous stirred tank reactor configuration. The reaction kinetics were characterized by first order rate constants for the disappearance of the parent compound; these ranged from 2.7 {times} 1{sup {minus}3} to 3.7 {times} 10{sup {minus}2} mm{sup {minus}1} over an applied power density range of 0.6 to 3.6 watt mL{sup {minus}1} and target concentration of approximately 25 to 900 {micro}M. The rate constant is shown to be inversely proportional to the target compound concentration, indicating higher order reaction kinetics. The conversion efficiency for the system was characterized through the G efficiency commonly used in radiation chemistry. The G efficiency ranged between 4 {times} 10{sup {minus}5} to 2.2 {times} 10{sup {minus}4} molecules destroyed per 100 eV of electrical energy drawn from the wall outlet. These values are comparable to those of other advanced oxidation processes. Suggestions are made regarding methods to improve this technology.

Thoma, G.; Gleason, M. [Univ. of Arkansas, Fayetteville, AR (United States). Dept. of Chemical Engineering; Popov, V. [Scientific Production Association Typhoon, Obninsk (Russian Federation). Inst. of Experimental Meterology

1998-12-31

377

Effect of nitrogen limitation on performance of toluene degrading biofilters.  

PubMed

The literature reports conflicting observations regarding the need for nutrient addition to biofilters treating contaminated gases. Such conflicts are often based on quasi-steady-state performance data collected on biofilters operated under continuous loading conditions. In the studies described herein, the impact of nitrogen limitations on two toluene-fed biofilters was assessed over a 97-day period. The biofilters were packed with polyurethane foam medium and contained different initial levels of nitrate-nitrogen. Toluene and CO2 concentration profiles were monitored during both normal steady loading conditions and short-term, unsteady-state transient loading conditions (e.g., shock loads). Packing medium samples were periodically removed and analyzed to quantify changes in nitrate-nitrogen content over time. Data are presented which show that over long-time periods (several months), nutrient-induced kinetic limitations diminished biofilter performance during transient, unsteady-state conditions even when performance during normal steady loading was not adversely affected. Elemental analysis of biomass removed from the biofilters support nitrate-nitrogen and CO2 concentration profile data and clearly illustrate how kinetically limited biofilters fail during shock loads even when there is an overall stoichiometric excess of nutrients. PMID:11317887

Moe, W M; Irvine, R L

2001-04-01

378

Nondisjunction induced in mouse spermatogenesis by chloral hydrate, a metabolite of trichloroethylene.  

PubMed

The effects of chloral hydrate (CH), an in vivo metabolite of trichloroethylene, have been evaluated by cytogenetic observations of mouse secondary spermatocytes after ip treatment with 82.7, 165.4, or 413.5 mg/kg bw. Hyper-haploid metaphases have been scored to determine whether previous observations in various nonmammalian organisms about an effect of this drug on the mitotic spindle could be confirmed in mice. At each dose, the frequencies of hyper-haploid cells have been estimated to assess the response of pachytene, preleptotene, premeiotic, and staminal gonial cells. Significant increases above the control value have been observed particularly after treatment of actively dividing gonial cells, confirming the results obtained with the same batch of the drug in a parallel collaborative investigation with Aspergillus nidulans. Thus: a) chloral hydrate has been shown to be effective in inducing nondisjunction in a mammalian system; b) a prevalent action on the mitotic spindle has been confirmed and quantified; and c) the usefulness of parallel investigations with different methods is stressed, particularly to collect information about the mechanisms of induction of nondisjunction events. PMID:6479114

Russo, A; Pacchierotti, F; Metalli, P

1984-01-01

379

Removal of trichloroethylene by zerovalent iron/activated carbon derived from agricultural wastes.  

PubMed

Activated carbon (AC) and zerovalent iron (ZVI) have been widely used in the adsorption and dehalogenation process, respectively, for the removal of organic compounds in environmental treatments. This study aims to prepare ZVI/AC derived from an agricultural waste, coir pith, through simple one-step pyrolysis. The effect of activation temperature and time on the surface area, iron content, and zerovalent iron ratio of ZVI/AC was systemically investigated. The results indicated that the activation of AC by FeSO4 significantly increased surface area of AC and distributed elemental iron over the AC. The X-ray diffraction (XRD), electron spectroscopy for chemical analysis (ESCA), and X-ray absorption near edge structure (XANES) spectra of ZVI/AC revealed that zerovalent iron was present. As compared to AC without FeSO4 activation, ZVI/AC increased the trichloroethylene removal rate constant by 7 times. The dechlorination ability of ZVI/AC was dominated by the zerovalent iron content. We have shown that lab-made ZVI/AC from coir pith can effectively adsorb and dehalogenate the chlorinated compounds in water. PMID:23994578

Su, Yuh-Fan; Cheng, Yu-Ling; Shih, Yang-Hsin

2013-08-28

380

Deactivation model for the adsorption of trichloroethylene vapor on an activated carbon bed  

SciTech Connect

In this work, the adsorption of trichloroethylene (TCE) vapor was investigated in a laboratory-scale packed-bed adsorber by using granular activated carbon (GAC) at constant pressure (101.3 kPa). The packed-bed adsorber (PBA) was operated batchwise with the charges of GAC particles in the ranges of 2.5--10.0 g for obtaining TCE breakthrough curves. Experiments were carried out at different temperatures (25.6 {le} T({degree}C) {le} 35.8) and TCE feedstock concentrations (6,350 {le} C (ppm TCE) {le} 7,950) within the range of space velocity (5,000 {le} {var_theta} (h{sup {minus}1}) {le} 17,000). The effects of TCE inlet concentration, operating temperature, and mass of adsorbent (m{sub Ads}) on the TCE breakthrough curves were investigated, respectively. The deactivation model (DM) was tested for these curves by using the analogy between the adsorption of TCE and the deactivation of catalyst particles. Observed adsorption rate constants (k{sub S}) and first-order deactivation rate constants (k{sub d}) were obtained from the model. It was found that the deactivation model describes the experimental breakthrough curves more accurately compared to the adsorption isotherms given in the literature.

Suyadal, Y.; Erol, M.; Oguz, H.

2000-03-01

381

Evaluation of the effectiveness of using alfalfa and buffalo grass for remediation of trichloroethylene from groundwater  

SciTech Connect

Phytoremediation is receiving increasing attention due to the potential for vegetation to play a significant role in bioremediation of contaminated soils and groundwater. The purpose of this research was to conduct a pilot study to determine if buffalo grass would enhance the remediation of groundwater contaminated with trichloroethylene (TCE). A mass-balance experiment was designed and executed to determine the extent of TCE remediation/degradation occurring through buffalo grass. Measurements for TCE in air, water, and soil were completed for three treatments: (1) buffalo grass, (2) alfalfa, and (3) soil following challenge with a water-TCE mixture. In total, 267 air samples, 43 water samples, 85 soil samples, and 40 vegetative samples were collected and analyzed. The analysis identified two important facts. First, there were no significant differences detected between TCE concentrations in soil, water, and air between groups. Second, there is a significant difference in the amount of the TCE-water mixture consumed in chambers with plants versus chambers without plants. The mass balance of the experiment was not achieved due to unaccountable losses of TCE from the chambers. The major loss mechanism for TCE appears to be from the breakthrough of air sampling media during the experiment. Thus, the data are insufficient to determine if remediation occurred via plants or by preferential pathways through the soil. Future experiments should be designed to include daily monitoring of the aquifer, humidity tolerant air sampling protocol, and relief from the build-up of humidity and transpiration inside the chambers.

Caravello, V.

1998-06-03

382

Effect of nitrogen source on growth and trichloroethylene degradation by methane-oxidizing bacteria  

SciTech Connect

The effect of nitrogen source on methane-oxidizing bacteria with respect to cellular growth and trichloroethylene (TCE) degradation ability were examined. One mixed chemostat culture and two pure type II methane-oxidizing strains, Methylosinus trichosporium OB3b and strain CAC-2, which was isolated from the chemostat culture, were used in this study. All cultures were able to grow with each of three different nitrogen sources: ammonia, nitrate, and molecular nitrogen. Both M. trichosporium OB3b and strain CAC-2 showed slightly lower net cellular growth rates and cell yields but exhibited higher methane uptake rates, levels of poly-{beta}-hydroxybutyrate (PHB) production, and naphthalene oxidation rates when grown under nitrogen-fixing conditions. The TCE-degrading ability of each culture was measured in terms of initial TCE oxidation rates and TCE transformation capacities, measured both with and without external energy sources. Higher initial TCE oxidation rates and TCE transformation capacities were observed in nitrogen-fixing mixed, M. trichosporium OB3b, and CAC-2 cultures than in nitrate- or ammonia-supplied cells. TCE transformation capacities were found to correlate with cellular PHB content in all three cultures. The results of this study suggest that the nitrogen-fixing capabilities of methane-oxidizing bacteria can be used to select for high-activity TCE degraders for the enhancement of bioremediation in fixed-nitrogen-limited environments.

Chu, K.H.; Alvarez-Cohen, L. [Univ. of California, Berkeley, CA (United States). Dept. of Civil and Environmental Engineering

1998-09-01

383

Continuous degradation of trichloroethylene by Xanthobacter sp. strain Py2 during growth on propene  

SciTech Connect

Propene-grown Xanthobacter sp. strain Py2 cells can degrade trichloroethylene (TCE), but the transformation capacity of such cells was limited and depended on both the TCE concentration and the biomass concentration. Toxic metabolites presumably accumulated extracellularly, because the fermentation of glucose by yeast cells was inhibited by TCE degradation products formed by strain Py2. The affinity of the propene monooxygenase for TCE was low, and this allowed strain Py2 to grow on propene in the presence of TCE. During batch growth with propene and TCE, the TCE was not degraded before most of the propene had been consumed. Continuous degradation of TCE in a chemostat culture of strain Py2 growing with propene was observed with TCE concentrations up to 206 {mu}M in the growth medium without washout of the fermentor occurring. At this TCE concentration the specific degradation rate was 1.5 nmol/min/mg of biomass. The total amount of TCE that could be degraded during simultaneous growth on propene depended on the TCE concentration and ranged from 0.03 to 0.34 g of TCE per g of biomass. The biomass yield on propene was not affected by the cometabolic degradation of TCE. 23 refs., 5 figs., 2 tabs.

Reij, M.W.; Kieboom, J.; De Bont, J.A.M.; Hartmans, S. [Wageningen Agricultural Univ. (Netherlands)

1995-08-01

384

The kinetics of the combustion of trichloroethylene for low Cl/H ratios  

SciTech Connect

A kinetic model has been developed for the combustion of trichloroethylene (TCE) under low Cl/H ratio conditions. Flame species concentration profiles, measured for CH{sub 4}/O{sub 2}/Ar flames, reveal that the most important reaction channels in the decomposition of TCE in the CH{sub 4}/TCE/O{sub 2}/Ar flame are the displacement by H atoms of Cl atoms from TCE,1,1-dichloroethylene (DCE), and vinyl chloride. The displacement of Cl atoms from TCE by OH also contributes to the decomposition of TCE, and leads to the production of 2,2-dichloroethanol, a species unobserved in previous flame studies. Other species found in large concentrations in the present CH{sub 4}/TCE/O{sub 2}/Ar flames, but not observed in previous TCE/O{sub 2}/Ar flame studies at higher chlorine-too-hydrogen ratios, are ketene, chloroketene, and dichloroketene. Finally, the presence of TCE catalyzes the formation of C{sub 3}-C{sub 6} hydrocarbons. The presence of significant concentrations of C{sub 3}H{sub 3}, C{sub 3}H{sub 4}, and C{sub 6}H{sub 6} is consistent with odd carbon species mechanisms previously suggested for benzene formation in hydrocarbon flames.

Werner, J.H.; Cool, T.A.

2000-01-01

385

E-beam treatment of trichloroethylene-air mixtures: products and rates  

NASA Astrophysics Data System (ADS)

Electron beam (E-beam) treatment of 3000 ppmv trichloroethylene (TCE) vapor in dry and wet air led to rapid, nearly quantitative, conversion of TCE to dichloroacetyl chloride, plus small amounts of phosgene. Higher E-beam doses, up to 110 kGy, led to oxidation of the initial products to CO, CO2, HCl and Cl2. The results parallel results found for photo- and Cl-atom initiated oxidation of TCE vapor, and are accounted for by an efficient Cl-atom chain oxidation. Lack of effect of 28,000 ppmv water vapor (90% RH) on rates or products reflects a very high efficiency for the Cl-atom chain oxidation and the very slow reaction of vapor phase water with acyl halides. Irradiation experiments conducted with TCE dissolved in aerated and deaerated water at 10 and 300 ppm showed marked differences in radiolytic products from those found in the vapor phase. A preliminary cost estimate indicates that E-beam treatment of TCE vapor is very competitive with conventional activated carbon treatment and catalytic oxidation.

Mill, Theodore; Su, Minggong; Yao, C. C. David; Matthews, Stephen M.; Wang, Francis T. S.

1997-09-01

386

Bioremediation of Trichloroethylene-Contaminated Sediments Augmented with a Dehalococcoides Consortia  

SciTech Connect

At the Department of Energy's (DOE) Savannah River Site (SRS) in Aiken, SC there are a number of sites contaminated with Chlorinated Ethenes (CE) due to past disposal practices. Sediments from two CE contaminated SRS locations were evaluated for trichloroethylene (TCE) biodegradation through anaerobic laboratory microcosms. The testing included addition of amendments and bioaugmentation of sediments. The anaerobic microcosms were first amended with substrates including acetate, lactate, molasses, soybean oil, methanol, sulfate, yeast extract, Regenesis HRC(R), and MEAL (methanol, ethanol, acetate, lactate mixture). Microcosms were analyzed after biostimulation for 9 months and no significant TCE biodegradation was observed. At 10 months, additional TCE, fresh amendments, and a mixed culture containing Dehalococcoides ethenogenes were added to active microcosms. A significant decrease in TCE concentrations and an increase in biodegradation products cis-dichloroethylene (cDCE) and vinyl chloride (VC) were noted within 2 weeks of bioaugmentation. Microcosms amended with lactate and sulfate showed complete transformation of TCE (3 ppm) to ethene within 40 days after bioaugmentation. Microcosms amended with other substrates - soybean oil, acetate, yeast extract, and methanol - also show enhanced biodegradation of TCE to ethene. Microcosms amended with molasses and Regenesis HRC showed limited TCE transformation. No TCE transformation was seen in killed control microcosms. On the basis of these successful results, plans are underway for field-scale in-situ deployment of biostimulation/bioaugmentation at SRS.

McKinsey, P.C.

2003-02-20

387

Supported Pd/Sn bimetallic nanoparticles for reductive dechlorination of aqueous trichloroethylene.  

PubMed

A Pd/Sn bimetallic nanoparticles resin (nano-Pd/Sn/resin) was successfully synthesized for reductive transformation of aqueous trichloroethylene (TCE). The physicochemical properties of the prepared resin were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, N(2) isothermal sorption at and X-ray photospectroscopy. The surface-area-normalized rate constants (k(SA)) of Sn particles in the nanoscale range (50-100 nm) were 4.5 times larger than the k(SA) for powdered Sn (0.04 mm). After depositing 1 wt% Pd onto nano-Sn surface, k(SA) was further enhanced by about a factor of 2. Groundwater constituents such as sulfide nitrate and dissolved oxygen had significant negative effects on the rate of TCE degradation by the nano-Pd/Sn/resin. A wet-chemical method regeneration method was observed to effectively restore the reactivity of the poisoned nano-Pd/Sn/resin after dipping in sulfide solution for 2d. In all cases, less than 0.5% of the degraded TCE appeared as chlorinated byproducts including the three dichloroethene isomers. The nano-Pd/Sn/resin technique performs well in transforming TCE into nontoxic hydrocarbons, as compared with other published methods. PMID:18992911

Lin, Chin Jung; Liou, Ya Hsuan; Lo, Shang-Lien

2008-11-06

388

Trichloroethylene-contaminated drinking water and congenital heart defects: a critical analysis of the literature.  

PubMed

The organic solvent trichloroethylene (TCE) is a metal degreasing agent and an intermediate in the production of fluorochemicals and polyvinyl chloride. TCE is also a common, persistent drinking water contaminant. Several epidemiological studies have alleged links between TCE exposure during pregnancy and offspring health problems including congenital heart defects (CHDs); however, the results of these studies are inconsistent, difficult to interpret, and involve several confounding factors. Similarly, the results of animal studies examining the potential of TCE to elicit cardiac anomalies have been inconsistent, and they have often been performed at doses far exceeding the highest levels ever reported in the drinking water. To determine what is known about the relationship between TCE and the incidence of CHDs, a comprehensive analysis of all available epidemiological data and animal studies was performed. Additionally, in vivo and in vitro studies examining possible mechanisms of action for TCE were evaluated. The specific types of heart defects alleged to have been caused by TCE in animal and human epidemiology studies were categorized by the morphogenetic process responsible for the defect in order to determine whether TCE might disrupt any specific developmental process. This analysis revealed that no single process was clearly affected by TCE, providing support that gestational TCE exposure does not increase the prevalence of CHDs. As a final evaluation, application of Hill's causality guidelines to the collective body of data revealed no indication of a causal link between gestational TCE exposure at environmentally relevant concentrations and CHDs. PMID:16181768

Watson, Rebecca E; Jacobson, Catherine F; Williams, Amy Lavin; Howard, W Brian; DeSesso, John M

2005-09-21

389

Immunological techniques as tools to characterize the subsurface microbial community at a trichloroethylene contaminated site  

SciTech Connect

Effective in situ bioremediation strategies require an understanding of the effects pollutants and remediation techniques have on subsurface microbial communities. Therefore, detailed characterization of a site's microbial communities is important. Subsurface sediment borings and water samples were collected from a trichloroethylene (TCE) contaminated site, before and after horizontal well in situ air stripping and bioventing, as well as during methane injection for stimulation of methane-utilizing microorganisms. Subsamples were processed for heterotrophic plate counts, acridine orange direct counts (AODC), community diversity, direct fluorescent antibodies (DFA) enumeration for several nitrogen-transforming bacteria, and Biolog [reg sign] evaluation of enzyme activity in collected water samples. Plate counts were higher in near-surface depths than in the vadose zone sediment samples. During the in situ air stripping and bioventing, counts increased at or near the saturated zone, remained elevated throughout the aquifer, but did not change significantly after the air stripping. Sporadic increases in plate counts at different depths as well as increased diversity appeared to be linked to differing lithologies. AODCs were orders of magnitude higher than plate counts and remained relatively constant with depth except for slight increases near the surface depths and the capillary fringe. Nitrogen-transforming bacteria, as measured by serospecific DFA, were greatly affected both by the in situ air stripping and the methane injection. Biolog[reg sign] activity appeared to increase with subsurface stimulation both by air and methane. The complexity of subsurface systems makes the use of selective monitoring tools imperative.

Fliermans, C.B.; Dougherty, J.M.; Franck, M.M.; McKinzey, P.C.; Hazen, T.C.

1992-01-01

390

Immunological techniques as tools to characterize the subsurface microbial community at a trichloroethylene contaminated site  

SciTech Connect

Effective in situ bioremediation strategies require an understanding of the effects pollutants and remediation techniques have on subsurface microbial communities. Therefore, detailed characterization of a site`s microbial communities is important. Subsurface sediment borings and water samples were collected from a trichloroethylene (TCE) contaminated site, before and after horizontal well in situ air stripping and bioventing, as well as during methane injection for stimulation of methane-utilizing microorganisms. Subsamples were processed for heterotrophic plate counts, acridine orange direct counts (AODC), community diversity, direct fluorescent antibodies (DFA) enumeration for several nitrogen-transforming bacteria, and Biolog {reg_sign} evaluation of enzyme activity in collected water samples. Plate counts were higher in near-surface depths than in the vadose zone sediment samples. During the in situ air stripping and bioventing, counts increased at or near the saturated zone, remained elevated throughout the aquifer, but did not change significantly after the air stripping. Sporadic increases in plate counts at different depths as well as increased diversity appeared to be linked to differing lithologies. AODCs were orders of magnitude higher than plate counts and remained relatively constant with depth except for slight increases near the surface depths and the capillary fringe. Nitrogen-transforming bacteria, as measured by serospecific DFA, were greatly affected both by the in situ air stripping and the methane injection. Biolog{reg_sign} activity appeared to increase with subsurface stimulation both by air and methane. The complexity of subsurface systems makes the use of selective monitoring tools imperative.

Fliermans, C.B.; Dougherty, J.M.; Franck, M.M.; McKinzey, P.C.; Hazen, T.C.

1992-12-31

391

Trichloroethylene transformation by natural mineral pyrite: the deciding role of oxygen.  

PubMed

The transformation of trichloroethylene (TCE) in natural mineral iron disulfide (pyrite) aqueous suspension under different oxygen conditions was investigated in laboratory batch experiments. TCE transformation was pursued by monitoring its disappearance and products released with time. The effect of oxygen was studied by varying the initial dissolved oxygen concentration (DO(i)) inside each reactor. Transformation rates depended strongly on DO(i) in the system. In anaerobic pyrite suspension, TCE did not transform as it did under aerobic conditions. The transformation rate increased with an increase in DO(i). The TCE transformation kinetics was fitted to a pseudo-first-order reaction with a rate constant k (h(-1)) varying from 0.004 to 0.013 for closed systems with DO(i) varying from 0.017 to 0.268 mmol/L under the experimental conditions. In the aerobic systems, TCE transformed to several organic acids including dichloroacetic acid, glyoxylic acid, oxalic acid, formic acid, and finally to CO2 and chloride ion. Dichloroacetic acid was the only chlorinated intermediate found. Both TCE and the pyrite surface were oxidized in the presence of O2. Oxygen consumption profiles showed O2 was the common oxidant in both TCE and pyrite oxidation reactions. Ferric ion cannot be used as an alternative oxidant to oxygen for TCE transformation. PMID:18939588

Pham, Hoa T; Kitsuneduka, Masashi; Hara, Junko; Suto, Koichi; Inoue, Chihiro

2008-10-01

392

In situ bioremediation of trichloroethylene-contaminated water by a resting-cell methanotrophic microbial filter  

SciTech Connect

The Lawrence Livermore National Laboratory is testing and developing an in situ microbial filter technology for remediating migrating subsurface plumes contaminated with low concentrations of trichloroethylene (TCE). Their current focus is the establishment of a replenishable bioactive zone (catalytic filter) along expanding plume boundaries by the Injection of a representative methanotrophic bacterium, Methylosinus trichosporium OB3b. We have successfully demonstrated this microbial filter strategy using emplaced, attached resting cells (no methane additions) in a 1.1-m flow-through test bed loaded with water-saturated sand. Two separate 24 h pulses of TCE (109 ppb and 85 ppb), one week apart, were pumped through the system at a flow velocity of 1.5 cm/h; no TCE (<0.5 ppb) was detected on the downstream side of the microbial filter. Subsequent excavation of the wet sand confirmed the existence of a TCE-bioactive zone 19 days after it had been created. An enhanced longevity of the cellular, soluble-form methane monooxygenase produced by this methanotroph Is a result of our laboratory bioreactor culturing conditions. Additional experiments with cells in sealed vials and emplaced in the 1.1-m test bed yielded a high resting-cell finite TCE biotransformation capacity of [approximately] 0.25 mg per mg of bacteria; this is suitable for a planned sand-filled trench field demonstration at a Lawrence Livermore National Laboratory site.

Taylor, R.T.; Duba, A.G.; Durham, W.B.; Hanna, M.L.; Jackson, K.J.; Jovanovich, M.C.; Knapp, R.B.; Knezovich, J.P.; Shah, N.N.; Shonnard, D.R.; Wijesinghe, A.M.

1992-10-01

393

In situ bioremediation of trichloroethylene-contaminated water by a resting-cell methanotrophic microbial filter  

SciTech Connect

The Lawrence Livermore National Laboratory is testing and developing an in situ microbial filter technology for remediating migrating subsurface plumes contaminated with low concentrations of trichloroethylene (TCE). Their current focus is the establishment of a replenishable bioactive zone (catalytic filter) along expanding plume boundaries by the Injection of a representative methanotrophic bacterium, Methylosinus trichosporium OB3b. We have successfully demonstrated this microbial filter strategy using emplaced, attached resting cells (no methane additions) in a 1.1-m flow-through test bed loaded with water-saturated sand. Two separate 24 h pulses of TCE (109 ppb and 85 ppb), one week apart, were pumped through the system at a flow velocity of 1.5 cm/h; no TCE (<0.5 ppb) was detected on the downstream side of the microbial filter. Subsequent excavation of the wet sand confirmed the existence of a TCE-bioactive zone 19 days after it had been created. An enhanced longevity of the cellular, soluble-form methane monooxygenase produced by this methanotroph Is a result of our laboratory bioreactor culturing conditions. Additional experiments with cells in sealed vials and emplaced in the 1.1-m test bed yielded a high resting-cell finite TCE biotransformation capacity of {approximately} 0.25 mg per mg of bacteria; this is suitable for a planned sand-filled trench field demonstration at a Lawrence Livermore National Laboratory site.

Taylor, R.T.; Duba, A.G.; Durham, W.B.; Hanna, M.L.; Jackson, K.J.; Jovanovich, M.C.; Knapp, R.B.; Knezovich, J.P.; Shah, N.N.; Shonnard, D.R.; Wijesinghe, A.M.

1992-10-01

394

Effects of Phenol Feeding Pattern on Microbial Community Structure and Cometabolism of Trichloroethylene  

PubMed Central

Cometabolism of trichloroethylene (TCE) by phenol-fed enrichments was evaluated in four reactors with distinct phenol feeding patterns. The reactors were inoculated from the same source, operated at the same average dilution rate, and received the same mass of phenol over time. Only the timing of phenol addition differed. Reactor C received phenol continuously; reactor SC5 received phenol semicontinuously--alternating between 5 h of feed and 3 h without feed; reactor SC2 alternated between 2 h of feed and 6 h without feed; and reactor P received a single pulse every 24 h. The structure of the enrichments and their capacity for TCE transformation were analyzed. In long-term operation, reactors C and SC5 were dominated by fungi, had higher levels of predators, were more susceptible to biomass fluctuations, and exhibited reduced capacity for TCE transformation. Reactors P and SC2 were characterized by lower levels of fungi, higher bacterial biomass, higher concentrations of TCE-degrading organisms, and higher rates of TCE transformation. After 200 days of operation, rates of TCE transformation increased 10-fold in reactor P, resulting in TCE transformation rates that were 20 to 100 times higher than the rates of the other reactor communities. The cause of this shift is unknown. Isolates capable of the highest rates of TCE transformation were obtained from reactor P. We conclude that cometabolic activity depends upon microbial community structure and that the community structure can be manipulated by altering the growth substrate feeding pattern.

Shih, C.; Davey, M. E.; Zhou, J.; Tiedje, J. M.; Criddle, C. S.

1996-01-01

395

Biodegradation of trichloroethylene and its anaerobic daughter products in freshwater wetland sediments  

USGS Publications Warehouse

Laboratory microcosms were prepared under methanogenic, sulfate-reducing, and aerobic conditions using sediment and groundwater from a freshwater wetland that is a discharge area for a trichloroethylene (TCE) to evaluate potential biodegradation rates of TCE and its anaerobic daughter products (cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, and vinyl chloride (VC)). Anaerobic degradation of TCE was about an order of magnitude faster under methanogenic conditions than under sulfate-reducing conditions. Both 12DCE and VC were found under sulfate-reducing conditions in the microcosms containing the wetland sediment, but their production, especially for VC, was substantially slower than under methanogenic conditions. Methane concentrations remained approximately constant (when losses in the formalin-amended controls are considered) in the microcosms amended with TCE and increased in the microcosms amended with the 12DCE isomers and VC during the first 18-25 days of incubation. The most rapid decrease in concentrations of TCE, cis-12DCE, trans-12DCE, and VC was found after aerobic methane-oxidizing conditions were definitely established.

Lorah, M. M.; Olsen, L. D.

2001-01-01

396

Second moment method for evaluating human health risks from groundwater contaminated by trichloroethylene.  

PubMed Central

Pollutants in groundwater aquifers may constitute a significant human health risk. A large variation in response may result among human populations experiencing the same level and duration of exposure to pollutants. Variability in response, as a result of exposure to a carcinogenic contaminant such as trichloroethylene (TCE), can be represented by a distribution function of safe doses. Spatial variability in aquifer characteristics and contaminant transport parameters requires the use of stochastic transport models to quantify variability in exposure concentrations. A second moment method is used to evaluate the probability of exceeding safe dose levels for a contaminated aquifer. The name of this method stems from the fact that the formulation is based on the first and second moments of the random variables. With this method, the probability is a function of the variability of contaminant concentration (which incorporates variability in hydrogeologic parameters such as hydraulic conductivity) and the variability in response in the human population. In this manner, the severity of the health risk posed by a contaminated aquifer and the evaluation of appropriate strategies and technologies for aquifer remediation are a function of contaminant concentrations and human health risks. The applicability and limitations of this method are demonstrated with data on groundwater contaminated by TCE at Hill Air Force Base, Utah. Images Figure 1. Figure 2. Figure 3. Figure 4.

Jacobs, T L; Warmerdam, J M; Medina, M A; Piver, W T

1996-01-01

397

In situ detection of organic molecules: Optrodes for TCE (trichloroethylene) and CHCl sub 3  

SciTech Connect

We have developed new absorption-based chemical indicators for detecting chloroform (CHCl{sub 3}) and trichloroethylene (TCE). These indicators were used to make very sensitive optical chemical sensors (optrodes) for each of these two contaminants. Concentrations below 10 ppb can be accurately measured using these sensors. Furthermore, they are selective and do not response to similar contaminants commonly found with TCE and CHCl{sub 3} in contaminated groundwater. In addition, the sensor response is linearly proportional to the chemical concentration. In this report, we describe the details of this optrode and the putative reaction sequences of the indicator chemistries with CHCl{sub 3} and TCE and present an analysis of the spectral data obtained from the reaction products. A key part of the development of this optrode was designing a simple readout device. The readout is a dual-channel fiber-optic fluorimeter modified to measure transmission or absorption of light. The system is controlled by a lap-top microcomputer and is fully field portable. In addition to describing the final absorption optrode, details of the chemical indicator reactions are presented for both absorption- (colorimetric) and fluorescence-based optrodes. Finally, we report on the syntheses of several compounds used to evaluate the indicator chemical reactions that led to the development of the absorption optrode. 23 refs., 26 figs., 1 tab.

Angel, S. M.; Langry, K. C.; Ridley, M. N.

1990-05-01

398

Regeneration of granular activated carbon with adsorbed trichloroethylene using wet peroxide oxidation.  

PubMed

The objective of this study is to clarify the regeneration of granular activated carbon (GAC) adsorbed trichloroethylene (TCE) using wet peroxide oxidation (WPO). TCE and TOC concentrations decreased during WPO, whereas Cl(-) accumulated in water indicating that TCE was not only decomposed but was also mineralized to Cl(-) and CO(2) using WPO. Regeneration efficiencies (q/q(0)) of GAC regenerated at 150, 165 and 180 degrees C (initial pH 4) were 0.36, 0.45, 0.48, respectively. In addition, regeneration efficiencies of GAC regenerated in the solution of various initial pH (2.5, 3.0, 4.0) at 180 degrees C were 0.71, 0.60, 0.48, respectively. These results suggest that regeneration of GAC is more effective at higher reaction temperature and lower initial pH of the solution. In the repeated regeneration of GAC, the adsorption capacity of GAC for TCE gradually decreased and regeneration efficiency of the regenerated GAC at sixth step was 0.40. The adsorption capacity loss of regenerated GAC is probably due to oxidation of GAC during WPO. PMID:17224174

Okawa, Kiyokazu; Suzuki, Kazuyoshi; Takeshita, Toshihiro; Nakano, Katsuyuki

2007-01-16

399

Biodegradation of trichloroethylene in continuous-recycle expanded-bed bioreactors  

SciTech Connect

Experimental bioreactors operated as recirculated closed systems were inoculated with bacterial cultures that utilized methane, propane, and tryptone-yeast extract as aerobic carbon and energy sources and degraded trichloroethylene (TCE). Up to 95% removal of TCE was observed after 5 days of incubation. Uninoculated bioreactors inhibited with 0.5% Formalin and 0.2% sodium azide retained greater than 95% of their TCE after 20 days. Each bioreactor consisted of an expanded-bed column through which the liquid phase was recirculated and a gas recharge column which allowed direct headspace sampling. Pulses of TCE (20 mg/liter) were added to bioreactors, and gas chromatography was used to monitor TCE, propane, methane, and carbon dioxide. Pulsed feeding of methane and propane with air resulted in 1 mol of TCE degraded per 55 mol of substrate utilized. Perturbation studies revealed the pH shifts from 7.2 to 7.5 decreased TCE degradation by 85%. The bioreactors recovered to baseline activities within 1 day after the pH returned to neutrality.

Phelps, T.J.; Niedzielski, J.J.; Schram, R.M. (Univ. of Tennessee, Knoxville, (USA)); Herbes, S.E.; White, D.C. (Oak Ridge National Lab., TN (USA))

1990-06-01

400

Effect of nanopore size distributions on trichloroethylene adsorption and desorption on carbogenic adsorbents  

SciTech Connect

Two carbon adsorbents, Ambersorb-600 and Ambersorb-563 (A-600 and A-563), were compared for vapor-phase trichloroethylene (TCE) adsorption from humid air streams. These adsorbents retained capacity for TCE in humid environments and were regenerable in situ. Enhanced desorption, and hence, increased working capacities, were achieved with bimodal pore size distributions and hydrophobic surface chemistry. Vapor-phase TCE isotherms confirmed that both of these adsorbents have high capacities for TCE. Only a small difference between the micropore size distributions of A-563 and A-600 was determined by room-temperature methyl chloride adsorption and the modified Horvath-Kawazoe model. Besides differences in particle size and pore volume there was a measurable, but small change, in the fraction of the pores in the ultramicropore range (5 {angstrom} or smaller) of the A-600 adsorbent versus that of A-563. In packed-bed breakthrough curve experiments, A-600 displayed a sharper mass-transfer zone than A-563, but maintained essentially the same capacity for TCE in a humid environment. Both materials were amenable to in-situ regeneration, and the A-600 provided higher overall working capacity than that of A-563.

Kane, M.S.; Bushong, J.H.; Foley, H.C. [Univ. of Delaware, Newark, DE (United States); Brendley, W.H. Jr. [Philadelphia Coll. of Textiles, Philadelphia, PA (United States). Dept. of Chemistry

1998-06-01

401

Redox control for electrochemical dechlorination of trichloroethylene in bicarbonate aqueous media.  

PubMed

The role of iron anode on electrochemical dechlorination of aqueous trichloroethylene (TCE) is evaluated using batch mixed-electrolyte experiments. A significantly higher dechlorination rate, up to 99%, is reported when iron anode and copper foam cathodes are used. In contrast to the oxygen-releasing inert anode, the cast iron anode generates ferrous species, which regulate the electrolyte to a reducing condition (low ORP value) and favor the reduction of TCE. The main products of TCE electrochemical reduction on copper foam cathode include ethene and ethane. The ratio of these two hydrocarbons gases varied with the electrolyte ORP condition and current density as more ethane gas generates at more reducing electrolyte condition and at higher current condition. A pseudofirst-order model is used to describe the degradation of TCE; the first-order rate constant (k) increases with the current applied but exhibits a negative relation with initial concentration. Depending on the current, electrolysis by iron anode causes a reduction in the ORP and an increase in the pH of the mixed electrolyte. Enhanced reaction rates in this investigation indicate that the electrochemical reduction using copper foam and iron anode may be a promising process for remediation of groundwater contaminated with chlorinated organic compounds. PMID:21671641

Mao, Xuhui; Ciblak, Ali; Amiri, Mohammad; Alshawabkeh, Akram N

2011-07-01

402

Microcosm and in situ field studies of enhanced biotransformation of trichloroethylene by phenol-utilizing microorganisms.  

PubMed Central

The ability of different aerobic groundwater microorganisms to cometabolically degrade trichloroethylene (TCE), 1,2-cis-dichloroethylene (c-DCE), and 1,2-trans-dichloroethylene (t-DCE) was evaluated both in groundwater-fed microcosms and in situ in a shallow aquifer. Microcosms amended with phenol or toulene were equally effective in removing c-DCE (> 90%) followed by TCE (60 to 70%), while the microcosm fed methane was most effective in removing t-DCE (> 90%). The microcosm fed ammonia was the least effective. None of the microcosms effectively degraded 1,1,1-trichloroethane. At the Moffett Field groundwater test site, in situ removal of c-DCE and TCE coincided with biostimulation through phenol and oxygen injection and utilization, with c-DCE removed more rapidly than TCE. Greater TCE and c-DCE removal was observed when the phenol concentration was increased. Over 90% removal of c-DCE and TCE was observed in the 2-m biostimulated zone. This compares with 40 to 50% removal of c-DCE and 15 to 25% removal of TCE achieved by methane-grown microorganisms previously evaluated in an adjacent in situ test zone. The in situ removal with phenol-grown microorganisms agrees qualitatively with the microcosm studies, with the rates and extents of removal ranked as follows: c-DCE > TCE > t-DCE. These studies demonstrate the potential for in situ TCE bioremediation using microorganisms grown on phenol.

Hopkins, G D; Semprini, L; McCarty, P L

1993-01-01

403

Reactions of water vapor or molecular hydrogen with trichloroethylene in a microwave plasma reactor  

SciTech Connect

The reaction of trichloroethylene (C/sub 2/HCl/sub 3/) with water vapor or molecular hydrogen has been studied in a low-pressure (ca. 5 Torr (0.67 kPa)) microwave plasma tubular flow reactor. The experimental apparatus included feed introduction systems, a microwave plasma reactor, and full product analysis by flame ionization and thermal-conductivity gas chromatography, mass spectrometry, and specific ion or pH detection for hydrogen chloride (HCl). Conversions of C/sub 2/HCl/sub 3/ in the range 50 to almost 100% are achieved. Product analyses indicate conversion to HCl, some light hydrocarbons, nonparent chlorocarbons, and soot C/sub (s)/. For the H/sub 2/O case, carbon monoxide and trace carbon dioxide were produced in place of some light hydrocarbons and C/sub (s)/. At least 85 mole % of chlorine (Cl) from the converted parent C/sub 2/HCl/sub 3/ forms thermodynamically stable HCl at parent conversions of 80% or more. The remaining chlorine was present as nonparent chlorocarbons. Preliminary kinetic analyses were performed. The global reaction in the plasma was found to follow one-half-order kinetic dependence on each of C/sub 2/HCl/sub 3/ and H/sub 2/O or H/sub 2/. Elementary plasma reaction mechanisms are presented to account for C/sub 2/HCl/sub 3/ conversion and the observed product distribution.

Bozzelli, J.W.; Barat, R.B.

1988-09-01

404

Lack of trigeminal nerve toxicity in rats exposed to trichloroethylene vapor for 13 weeks.  

PubMed

Male and female Fischer-344 rats were exposed to 1,1,2-trichloroethylene (TCE) at 250, 800, or 2500 ppm for 6 h/day, 5 days/week, for 13 weeks. Weekly body weights and daily clinical observations were recorded and a functional observational battery (FOB) was performed monthly. Postexposure neurotoxicological evaluations included an electrodiagnostic evaluation of auditory function, the trigeminal nerve, and a comprehensive neuropathological examination. After 8 weeks of exposure, female, but not male, rats exposed to 2500 ppm were slightly more reactive to handling than the controls but not after 13 weeks of exposure. After 13 weeks, female rats exposed to 2500 ppm TCE were slightly more active during the 1-min observation period than the controls. There were no treatment-related differences in grip performance, landing foot splay, or on the trigeminal nerve-evoked potential at any dose. At 2500 ppm TCE, mild frequency-specific hearing deficits were observed, including elevated tone-pip auditory brainstem response thresholds. Focal loss of hair cells in the upper basal turn of the cochlea was observed in 2500 ppm-exposed rats. Except for the cochleas of 2500 ppm-exposed rats, no treatment-related lesions were noted during the neuro-histopathologic examination. The no-observable-adverse-effect level for this study was 800 ppm based on ototoxicity at 2500 ppm. PMID:17132611

Albee, Ralph R; Spencer, Pamela J; Johnson, Keith A; Bradley, Greg J; Marable, Brian R; Wilmer, Jan W; Mattsson, Joel L

405

A pilot study on the stability of toluene in blood from workers  

PubMed Central

Background Biological monitoring is used to assess toluene exposure in medical examinations. The American Conference of Industrial Hygienists, Japanese Society for Occupational Health and Deutsche Forschungsgemeinschaft have proposed various biological exposure determinants, such as toluene in blood and urine, and o-cresol in urine. Toluene in blood is a common biomarker among them. Toluene is a volatile organic solvent; therefore, sample preservation under appropriate conditions before measurement is necessary. However, little study has been done on the stability of toluene in workers’ blood samples under conditions simulating those of a medical examination. Finding We carried out a pilot study on the stability of toluene in blood from humans, according to different methods of sample preservation. Toluene in blood was analyzed by head space-gas chromatography/mass spectrometry. The sealing performance of the vial was examined by using toluene-added blood and the stability of toluene in blood according to the preservation period was examined by using blood from toluene-handling workers, which was collected with vacuum blood tubes. The sealing performance of the headspace vial used in this study was good for three days and toluene in blood in tubes from workers was stable at least within 8 hours up to blood packing at 4°C. Conclusion We could propose that the collected blood need only be transferred into headspace vials on the collection day and analyzed within a few days, if the samples are preserved at 4°C. Our data size is limited; however, it may be considered basic information for biological monitoring in medical examinations.

2012-01-01

406

Health risk assessment of exposure to selected volatile organic compounds emitted from an integrated iron and steel plant.  

PubMed

Workplace air samples from sintering, cokemaking, and hot and cold forming processes in the integrated iron and steel industry were analyzed to determine their volatile organic compound (VOC) concentration. Sixteen VOC species including three paraffins (cyclohexane, n-hexane, methylcyclohexane), five chlorinated VOC species (trichloroethylene, 1,1,1-trichloroethane, tetrachloroethylene, chlorobenzene, 1,4-dichlorobenzene), and eight aromatics (benzene, ethylbenzene, styrene, toluene, m,p-xylene, o-xylene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene) were selected to measure their noncancer risk for workers. Concentrations of toluene, xylene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, dichlorobenzene, and trichloroethylene were high in all four processes. Carbon tetrachloride and tetrachloroethylene concentrations were high in the hot and cold forming processes. The noncancer risk followed the increasing order: cokemaking > sintering > hot forming > cold forming. 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene contributed 44% to 65% and 13% to 20% of noncancer risk, respectively, for the four processes. Benzene accounted for a high portion of the noncancer risk in cokemaking. The hazard index (HI: 17-108) of the average VOC concentrations suggests that health risks can be reduced by improving workplace air quality and protecting workers. PMID:20828338

Chang, E-E; Wei-Chi, Wang; Li-Xuan, Zeng; Hung-Lung, Chiang

2010-09-10

407

Stable hydrogen and carbon isotope fractionation during microbial toluene degradation: mechanistic and environmental aspects.  

PubMed

Primary features of hydrogen and carbon isotope fractionation during toluene degradation were studied to evaluate if analysis of isotope signatures can be used as a tool to monitor biodegradation in contaminated aquifers. D/H hydrogen isotope fractionation during microbial degradation of toluene was measured by gas chromatography. Per-deuterated toluene-d(8) and nonlabeled toluene were supplied in equal amounts as growth substrates, and kinetic isotope fractionation was calculated from the shift of the molar ratios of toluene-d(8) and nondeuterated toluene. The D/H isotope fractionation varied slightly for sulfate-reducing strain TRM1 (slope of curve [b] = -1.219), Desulfobacterium cetonicum (b = -1.196), Thauera aromatica (b = -0.816), and Geobacter metallireducens (b = -1.004) and was greater for the aerobic bacterium Pseudomonas putida mt-2 (b = -2.667). The D/H isotope fractionation was 3 orders of magnitude greater than the (13)C/(12)C carbon isotope fractionation reported previously. Hydrogen isotope fractionation with nonlabeled toluene was 1.7 and 6 times less than isotope fractionation with per-deuterated toluene-d(8) and nonlabeled toluene for sulfate-reducing strain TRM1 (b = -0.728) and D. cetonicum (b = -0.198), respectively. Carbon and hydrogen isotope fractionation during toluene degradation by D. cetonicum remained constant over a growth temperature range of 15 to 37 degrees C but varied slightly during degradation by P. putida mt-2, which showed maximum hydrogen isotope fractionation at 20 degrees C (b = -4.086) and minimum fractionation at 35 degrees C (b = -2.138). D/H isotope fractionation was observed only if the deuterium label was located at the methyl group of the toluene molecule which is the site of the initial enzymatic attack on the substrate by the bacterial strains investigated in this study. Use of ring-labeled toluene-d(5) in combination with nondeuterated toluene did not lead to significant D/H isotope fractionation. The activity of the first enzyme in the anaerobic toluene degradation pathway, benzylsuccinate synthase, was measured in cell extracts of D. cetonicum with an initial activity of 3.63 mU (mg of protein)(-1). The D/H isotope fractionation (b = -1.580) was 30% greater than that in growth experiments with D. cetonicum. Mass spectroscopic analysis of the product benzylsuccinate showed that H atoms abstracted from the toluene molecules by the enzyme were retained in the same molecules after the product was released. Our findings revealed that the use of deuterium-labeled toluene was appropriate for studying basic features of D/H isotope fractionation. Similar D/H fractionation factors for toluene degradation by anaerobic bacteria, the lack of significant temperature dependence, and the strong fractionation suggest that analysis of D/H fractionation can be used as a sensitive tool to assess degradation activities. Identification of the first enzyme reaction in the pathway as the major fractionating step provides a basis for linking observed isotope fractionation to biochemical reactions. PMID:11571192

Morasch, B; Richnow, H H; Schink, B; Meckenstock, R U

2001-10-01

408

Protein Engineering of Toluene Monooxygenases for Synthesis of Chiral Sulfoxides?  

PubMed Central

Enantiopure sulfoxides are valuable asymmetric starting materials and are important chiral auxiliaries in organic synthesis. Toluene monooxygenases (TMOs) have been shown previously to catalyze regioselective hydroxylation of substituted benzenes and phenols. Here we show that TMOs are also capable of performing enantioselective oxidation reactions of aromatic sulfides. Mutagenesis of position V106 in the ?-hydroxylase subunit of toluene ortho-monooxygenase (TOM) of Burkholderia cepacia G4 and the analogous position I100 in toluene 4-monooxygenase (T4MO) of Pseudomonas mendocina KR1 improved both rate and enantioselectivity. Variant TomA3 V106M of TOM oxidized methyl phenyl sulfide to the corresponding sulfoxide at a rate of 3.0 nmol/min/mg protein compared with 1.6 for the wild-type enzyme, and the enantiomeric excess (pro-S) increased from 51% for the wild type to 88% for this mutant. Similarly, T4MO variant TmoA I100G increased the wild-type oxidation rate by 1.7-fold, and the enantiomeric excess rose from 86% to 98% (pro-S). Both wild-type enzymes showed lower activity with methyl para-tolyl sulfide as a substrate, but the improvement in the activity and enantioselectivity of the mutants was more dramatic. For example, T4MO variant TmoA I100G oxidized methyl para-tolyl sulfide 11 times faster than the wild type did and changed the selectivity from 41% pro-R to 77% pro-S. A correlation between regioselectivity and enantioselectivity was shown for TMOs studied in this work. Using in silico homology modeling, it is shown that residue I100 in T4MO aids in steering the substrate into the active site at the end of the long entrance channel. It is further hypothesized that the main function of V106 in TOM is the proper positioning or docking of the substrate with respect to the diiron atoms. The results from this work suggest that when the substrate is not aligned correctly in the active site, the oxidation rate is decreased and enantioselectivity is impaired, resulting in products with both chiral configurations.

Feingersch, Roi; Shainsky, Janna; Wood, Thomas K.; Fishman, Ayelet

2008-01-01

409

CHANGES IN MRNA EXPRESSION PROFILES IN RAT CORTEX AND STRIATUM FOLLOWING SUB CHRONIC TOLUENE EXPOSURE.  

EPA Science Inventory

Toluene, a volatile organic compound (VOC) used in many commercial products, is a ubiquitous air pollutant and therefore of interest to many EPA regulatory programs. A primary concern for toluene and other VOCâ??s is the potential for persistent neurotoxic effects from long term e...

410

Detection of toluene dissolved in water by using PCS fibers excited by an inclined collimated beam  

Microsoft Academic Search

This paper reports results on the sensitivity of straight polymer-clad silica (PCS) detection fibers with short sensing parts coated with polysiloxane polymers to toluene dissolved in water. The detection was based on refractive index changes of the polymers induced by the penetration of toluene into them. These changes were detected by measuring changes of the output power from the detection

Vlastimil Matejec; Miroslav Chomát; Daniela Berkova; Jan Mrazek; Rodinel Ardeleanu; Valeria Harabagiu; Marianna Pinteala; Bogdan C Simionescu

2003-01-01

411

Interactions between benzene, toluene, and p-xylene (BTX) during their biodegradation  

Microsoft Academic Search

A microbial consortium and Pseudomonas strain (PPO1) were used in studying biodegradation of benzene, toluene, and p-xylene under aerobic conditions. Studies involved removal of each compound individually as well as in mixture with the others. Both cultures exhibited a qualitatively similar behavior toward each compound. Both the pure culture and the consortium grew on benzene following Monod kinetics, on toluene

Young-Sook Oh; R. Bartha; Z. Shareefdeen; B. C. Baltzis

1994-01-01

412

Toluene recycle in the synthesis of TATB. Progress report, October--December 1975  

Microsoft Academic Search

Laboratory and pilot-plant aminations of trichlorotrinitrobenzene have shown that the toluene reaction solvent can be recycled at least once without purification and without significantly degrading the TATB product. Subsequent recycles of the toluene results in smaller particle size TATB.

V. H. Evans; W. T. Quinlin; C. L. Schaffer; Z. L. Estes

1975-01-01

413

Toward Cost-Benefit Analysis of Acute Behavioral Effects of Toluene in Humans  

Microsoft Academic Search

There is increasing interest in being able to express the consequences of exposure to potentially toxic compounds in monetary terms in order to evaluate potential cost-benefit relationships of controlling exposure. Behavioral effects of acute toluene exposure could be subjected to cost-benefit analysis if the effects of toluene were quantitatively compared to those of ethanol ingestion, which has been monetized for

Vernon A. Benignus; Philip J. Bushnell; William K. Boyes

2005-01-01

414

WHY DO THE ACUTE BEHAVIORAL EFFECTS OT TOLUENE IN RATS DEPEND ON THE ROUTE OF EXPOSURE?  

EPA Science Inventory

Despite evidence suggesting that the acute effects of organic solvents are related to their concentration in the brain, we have observed route-dependent differences in the acute behavioral effects of toluene. Whereas inhaled toluene disrupts the performance of rats on a visual si...

415

Use of Selective Inhibitors and Chromogenic Substrates to Differentiate Bacteria Based on Toluene Oxygenase Activity  

SciTech Connect

In whole-cell studies, two alkynes, 1-pentyne and phenylacetylene, were selective, irreversible inhibitors of monooxygenase enzymes in catabolic pathways that permit growth of bacteria on toluene. 1-Pentyne selectively inhibited growth of Burkholderia cepacia G4 (toluene 2-monooxygenase [T2MO] pathway) and B. pickettii PKO1 (toluene 3-monooxygenase [T3MO] pathway) on toluene, but did not inhibit growth of bacteria expressing other pathways. In further studies with strain G4, chromogenic transformation of a,a,a-Trifluoro-m-cresol (TFC) was irreversibly inhibited by 1-pentyne, but the presence of phenol prevented this inhibition. Transformation of catechol by G4 was unaffected by 1-pentyne. With respect to the various pathways and bacteria tested, phenylacetylene selectively inhibited growth of Pseudomonas mendocina KR1 (toluene 4-monooxygenase [T4MO] pathway) on toluene, but not on p-cresol. An Escherichia coli transformant expressing T4MO transformed indole or naphthalene in chromogenic reactions, but not after exposure to phenylacetylene. The naphthalene reaction remained diminished in phenylacetylene-treated cells relative to untreated cells after phenylacetylene was removed, indicating irreversible inhibition. These techniques were used to differentiate toluene-degrading isolates from an aquifer. Based on data generated with these indicators and inhibitors, along with results from Biolog analysis for sole carbon source oxidation, the groundwater isolates were assigned to eight separate groups, some of which apparently differ in their mode of toluene catabolism.

Keener, William Kelvin; Schaller, Kastli Dianne; Walton, Michelle Rene; Partin, Judy Kaye; Watwood, Mary Elizabeth; Smith, William Aaron; Chingenpeel, S. R.

2001-09-01

416

Examining the Impact of an Updated Toluene Mechanism on Air Quality in the Eastern US  

EPA Science Inventory

Model simulations were performed using the CB05 chemical mechanism containing the base and an updated toluene mechanisms for the eastern US. The updated toluene mechanism increased monthly mean 8-hr ozone by 1.0-2.0 ppbv in urban areas of Chicago, the northeast US, Detroit, Cleve...

417

Aerobic and Anaerobic Toluene Degradation by a Newly Isolated Denitrifying Bacterium, Thauera sp. Strain DNT-1  

PubMed Central

A newly isolated denitrifying bacterium, Thauera sp. strain DNT-1, grew on toluene as the sole carbon and energy source under both aerobic and anaerobic conditions. When this strain was cultivated under oxygen-limiting conditions with nitrate, first toluene was degraded as oxygen was consumed, while later toluene was degraded as nitrate was reduced. Biochemical observations indicated that initial degradation of toluene occurred through a dioxygenase-mediated pathway and the benzylsuccinate pathway under aerobic and denitrifying conditions, respectively. Homologous genes for toluene dioxygenase (tod) and benzylsuccinate synthase (bss), which are the key enzymes in aerobic and anaerobic toluene degradation, respectively, were cloned from genomic DNA of strain DNT-1. The results of Northern blot analyses and real-time quantitative reverse transcriptase PCR suggested that transcription of both sets of genes was induced by toluene. In addition, the tod genes were induced under aerobic conditions, whereas the bss genes were induced under both aerobic and anaerobic conditions. On the basis of these results, it is concluded that strain DNT-1 modulates the expression of two different initial pathways of toluene degradation according to the availability of oxygen in the environment.

Shinoda, Yoshifumi; Sakai, Yasuyoshi; Uenishi, Hiroshi; Uchihashi, Yasumitsu; Hiraishi, Akira; Yukawa, Hideaki; Yurimoto, Hiroya; Kato, Nobuo

2004-01-01

418

Toxicity of Aromatic Aerobic Biotransformation Products of Toluene to Hela Cells  

Microsoft Academic Search

Petroleum contamination of groundwater is widely recognized as a serious environmental problem. Toluene (methylbenzene) occurs naturally in crude oil and is commonly found as a contaminant in the subsurface as a result of waste disposal and storage activities. Biological transformation and volatilization are the major removal mechanisms for toluene contamination of soils and groundwater. Biological transformation may be expedited through

Y. Shen

1998-01-01

419

Anaerobic degradation of toluene and o-xylene by a methanogenic consortium.  

PubMed Central

Toluene and o-xylene were completely mineralized to stoichiometric amounts of carbon dioxide, methane, and biomass by aquifer-derived microorganisms under strictly anaerobic conditions. The source of the inoculum was creosote-contaminated sediment from Pensacola, Fla. The adaptation periods before the onset of degradation were long (100 to 120 days for toluene degradation and 200 to 255 days for o-xylene). Successive transfers of the toluene- and o-xylene-degrading cultures remained active. Cell density in the cultures progressively increased over 2 to 3 years to stabilize at approximately 10(9) cells per ml. Degradation of toluene and o-xylene in stable mixed methanogenic cultures followed Monod kinetics, with inhibition noted at substrate concentrations above about 700 microM for o-xylene and 1,800 microM for toluene. The cultures degraded toluene or o-xylene but did not degrade m-xylene, p-xylene, benzene, ethylbenzene, or naphthalene. The degradative activity was retained after pasteurization or after starvation for 1 year. Degradation of toluene and o-xylene was inhibited by the alternate electron acceptors oxygen, nitrate, and sulfate. Degradation was also inhibited by the addition of preferred substrates such as acetate, H2, propionate, methanol, acetone, glucose, amino acids, fatty acids, peptone, and yeast extract. These data suggest that the presence of natural organic substrates or contaminants may inhibit anaerobic degradation of pollutants such as toluene and o-xylene at contaminated sites. Images

Edwards, E A; Grbic-Galic, D

1994-01-01

420

EVALUATING THE NMDA-GLUTAMATE RECEPTOR AS A SITE OF ACTION FOR TOLUENE, IN VIVO  

EPA Science Inventory

In vitro, toluene disrupts the function of NMDA-glutamate receptors, indicating that effects on NMDA receptor function may contribute to toluene neurotoxicity. NMDA-glutamate receptors are widely present in the visual system and contribute to pattern-elicited visual evoked potent...

421

Anaerobic degradation of toluene and o-xylene by a methanogenic consortium  

SciTech Connect

Toluene and o-xylene were completely mineralized to stoichiometric amounts of carbon dioxide, methane, and biomass by aquifer-derived microorganisms under strictly anaerobic conditions. The source of the inoculum was creosote-contaminated sediment from Pensacola, Fla. The adaptation periods before the onset of degradation were long (100 to 120 days for toluene degradation and 200 to 255 days for o-xylene). Successive transfers of the toluene- and o-xylene-degrading cultures remained active. Cell density in the cultures progressively increased over 2 to 3 years to stabilize at approximately 10[sup 9] cells per ml. Degradation of toluene and o-xylene in stable mixed methanogenic cultures followed Monod kinetics, with inhibition noted at substrate concentrations above about 700 [mu]M for o-xylene, and 1,800 [mu]M for toluene. The cultures degraded toluene or o-xylene but did not degrade m-xylene, p-xylene, benzene, ethylbenzene, or naphthalene. The degradative activity was retained after pasteurization or after starvation for 1 year. Degradation of toluene and o-xylene was inhibited by the alternate electron acceptors oxygen, nitrate, and sulfate. Degradation was also inhibited by the addition of preferred substrates such as acetate, H[sub 2] propionate, methanol, acetone, glucose, amino acids, fatty acids, peptone, and yeast extract. These data suggest that the presence of natural organic substrates or cocontaminants may inhibit anaerobic degradation of pollutants such as toluene and o-xylene at contaminated sites.

Edwards, E.A.; Grbic-Galic, D. (Stanford Univ., CA (United States))

1994-01-01

422

Simultaneous removal of ethyl acetate and toluene in air streams using compost-based biofilters.  

PubMed

Biofitration was successfully applied to treat air streams containing a mixture of ethyl acetate and toluene. The experiment was performed by two identical bench-scale biofilters, which were acclimated by ethyl acetate and toluene, respectively. During a 3 month steady-state performance, the two biofilters showed equivalent elimination capacity (EC) for toluene (50 g/m(3) bed/h of pure toluene). However, the biofilter acclimated with ethyl acetate showed a much higher EC for ethyl acetate (400 g/m(3) bed/h of pure ethyl acetate) than that acclimated with toluene (250 g/m(3) bed/h). The concurrent biofiltration of toluene was inhibited by the presence of ethyl acetate. The results also showed that more nitrogen and phosphorus were consumed in the process of the biofiltration of toluene compared with the treatment of ethyl acetate. After the 3 month experiment, the pH of the media treating ethyl acetate dropped from 6.71 to 5.50, whereas the pH of the media treating toluene increased from 6.71 to 7.08. PMID:12409249

Liu, Yonghui; Quan, Xie; Sun, Yumei; Chen, Jingwen; Xue, Daming; Chung, Jong Shik

2002-11-11

423

NEUROPHYSIOLOGICAL EFFECTS OF 30 DAY CHRONIC EXPOSURE TO TOLUENE IN RATS  

EPA Science Inventory

Long-Evans hooded rats were exposed to 1000 ppm toluene or 0 ppm toluene 6 hr/day, 5 days/week for 30 days. Following removal from the exposure conditions (18-26 hr) flash-evoked potentials were recorded to paired light flashes and pentylenetetrazol (PTZ) seizure properties were ...

424

Abatement of toluene from gas streams via ferro-electric packed bed dielectric barrier discharge plasma  

Microsoft Academic Search

Destruction of gaseous toluene via ferro-electric packed bed dielectric barrier discharge plasma in a coaxial cylindrical reactor was carried out at atmospheric pressure and room temperature. The difference among three kinds of reactors was compared in terms of specific energy density (SED), energy yield (EY), toluene decomposition. In order to optimize the geometry of the reactor, the removal efficiency of

Wenjun Liang; Jian Li; Jie Li; Yuquan Jin

2009-01-01

425

Abatement of toluene from gas streams via ferro-electric packed bed dielectric barrier discharge plasma.  

PubMed

Destruction of gaseous toluene via ferro-electric packed bed dielectric barrier discharge plasma in a coaxial cylindrical reactor was carried out at atmospheric pressure and room temperature. The difference among three kinds of reactors was compared in terms of specific energy density (SED), energy yield (EY), toluene decomposition. In order to optimize the geometry of the reactor, the removal efficiency of toluene was compared for various inner electrode diameters. In addition, qualitative analysis on by-products and particular discussion on toluene abatement mechanisms were also presented. It has been found that ferro-electric packed bed DBD reactor could effectively decompose toluene. Toluene removal efficiency enhanced with increasing SED. With respect to toluene conversion, 1.62 mm electrode appeared to be superior to 1.06 mm electrodes. BaTiO3 reactor had the highest toluene removal efficiency among the reactors. For NaNO2 reactor, the highest EY could reach 17.0 mg/kWh to a certain extent. PMID:19515490

Liang, Wenjun; Li, Jian; Li, Jie; Jin, Yuquan

2009-05-18

426

Analysis of wax solubility of rubber vulcanizates using wax solution in toluene and molten wax  

Microsoft Academic Search

Wax is commonly used as an antidegradant for rubber materials by formation of an impervious barrier. Wax solubilities in natural rubber (NR), styrene–butadiene rubber (SBR), and butadiene rubber (BR) vulcanizates were measured using wax solution in toluene and molten wax. Wax solubilities using molten wax were much higher than those using wax solution in toluene. The wax solubility of NR

Sung-Seen Choi; Song-Hee Im; Je-Hwan Park; Jae Seong Kim

2009-01-01

427

Toluene inhibits voltage-sensitive calcium channels expressed in pheochromocytoma cells  

Microsoft Academic Search

Commercial solvents such as toluene are commonly used as drugs of abuse by children and adolescents. The cellular and molecular sites and mechanisms of actions of these compounds are not well studied but their effects on behavior resemble those of central nervous system depressants such as alcohol, barbiturates and benzodiazepines. In this study, the effects of toluene on voltage-sensitive calcium

Riddick Tillar; Timothy J. Shafer; John J. Woodward

2002-01-01

428

Incorporation of oxygen from water into toluene and benzene during anaerobic fermentative transformation  

Microsoft Academic Search

Toluene and benzene were anaerobically transformed and eventually mineralized in mixed methanogenic cultures. However, the source of oxygen for the initial oxidation step had been unknown, owing to the presence of both methanol and water. No exogenous electron acceptors other than carbon dioxide, toluene, and benzene were present in the defined mineral medium. Through the use of ¹⁸O-labeled water, the

T. M. Vogel; D. Grbic-Galic

1986-01-01

429

Metabolites formed during anaerobic transformation of toluene and o-xylene and their proposed relationship to the initial steps of toluene mineralization  

SciTech Connect

Strain T1 is a facultative bacterium that is capable of anaerobic toluene degradation under denitrifying conditions. While 80% of the carbon from toluene is either oxidized to carbon dioxide or assimilated into cellular carbon, a significant portion of the remainder is transformed into two dead-end metabolites. These metabolites were produced simultaneous to the mineralization of toluene and were identified as benzylsuccinic acid and benzylfumaric acid. Identification was based on comparison of mass spectra of the methyl esters of the metabolites and authentic compounds that were chemically synthesized. Strain T1 is also capable of o-xylene transformation during growth on toluene, o-Xylene does not serve as a source of carbon and is not mineralized. Rather, it is transformed to analogous dead-end metabolites, (2-methylbenzyl)-succinic acid and (2-methyl-benzyl)-fumaric acid. o-Xylene transformation also occurred during growth on succinic acid, which suggests that attack of the methyl group by succinyl-coenzyme A is a key reaction in this transformation. The authors reason that the main pathway for toluene oxidation to carbon dioxide involves a mechanism similar to that for the formation of the metabolites and involves an attack of the methyl group of toluene by acetyl-coenzyme A.

Evans, P.J.; Ling, W.; Goldschmidt, B.; Young, L.Y. (New York Univ., NY (United States)); Ritter, E.R. (New Jersey Inst. of Tech., Newark (United States))

1992-02-01

430

Hydrodealkylation of toluene using hydrogen-rich reformer gas  

SciTech Connect

A combination unit for benzene production has been put into service at the Ryazan refinery for purposes of using the excess hydrogen-rich reformer gas produced there. The unit consists of sections for catalytic toluene hydrodealkylation, organic treatment of hydrogen-rich gas, and hydrogen production. When using reformer gas in the hydrodealkylation section the benzene production unit was modified to eliminate the hydrogen production section. Provisions are made for supplying the excess reformer gas in two different methods depending on hydrogen content. A material balance analysis before and after modifying the unit demonstrates that operating costs are reduced by lower consumption of fuel gas and treated water. Hydrogen sulfide content, and its favorable effect on the aluminia-chromia catalyst, is controlled by initial passage of the gas through the naphtha hydrotreating section of the reformer. Making the reformer gas heavier was also found to result in enhanced compressor reliability in the diesel fuel hydrotreating unit.

Golubyatnikov, V.I.; Kapustin, V.M.; Lugovskoi, A.I.

1988-05-01

431

Impact of a new condensed toluene mechanism on air quality model predictions in the US  

NASA Astrophysics Data System (ADS)

A new condensed toluene mechanism is incorporated into the Community Multiscale Air Quality Modeling system. Model simulations are performed using the CB05 chemical mechanism containing the existing (base) and the new toluene mechanism for the western and eastern US for a summer month. With current estimates of tropospheric emission burden, the new toluene mechanism increases monthly mean daily maximum 8-h ozone by 1.0-3.0 ppbv in Los Angeles, Portland, Seattle, Chicago, Cleveland, northeastern US, and Detroit compared to that with the base toluene chemistry. It reduces model mean bias for ozone at elevated observed ozone concentrations. While the new mechanism increases predicted ozone, it does not enhance ozone production efficiency. A sensitivity study suggests that it can further enhance ozone if elevated toluene emissions are present. While it increases in-cloud secondary organic aerosol substantially, its impact on total fine particle mass concentration is small.

Sarwar, G.; Appel, K. W.; Carlton, A. G.; Mathur, R.; Schere, K.; Zhang, R.; Majeed, M. A.

2011-03-01

432

Impact of a new condensed toluene mechanism on air quality model predictions in the US  

NASA Astrophysics Data System (ADS)

A new condensed toluene mechanism is incorporated into the Community Multiscale Air Quality Modeling system. Model simulations are performed using the CB05 chemical mechanism containing the existing (base) and the new toluene mechanism for the western and eastern US for a summer month. With current estimates of tropospheric emission burden, the new toluene mechanism increases monthly mean daily maximum 8-h ozone by 1.0-3.0 ppbv in Los Angeles, Portland, Seattle, Chicago, Cleveland, northeastern US, and Detroit compared to that with the base toluene chemistry. It reduces model mean bias for ozone at elevated observed ozone mixing ratios. While the new mechanism increases predicted ozone, it does not enhance ozone production efficiency. Sensitivity study suggests that it can further enhance ozone if elevated toluene emissions are present. While changes in total fine particulate mass are small, predictions of in-cloud SOA increase substantially.

Sarwar, G.; Appel, K. W.; Carlton, A. G.; Mathur, R.; Schere, K.; Zhang, R.; Majeed, M. A.

2010-12-01

433

Toluene inhalation induced changes of gene expression in rat brain: fluorescence differential display PCR analysis.  

PubMed

Toluene, an abused substance in Japan, is well known as a neurotoxic chemical and has been shown to have neurobehavioral and electrophysiological effects. We used a fluorescence differential display PCR technique to analyze the genes expressed in the brain by toluene inhalation. We found 20 genes that were differentially expressed by toluene exposure. We confirmed by re-amplified PCR, nucleotide sequence and quantitative real-time PCR that of the 20 cDNAs, only 10 showed reproducible expression patterns by toluene inhalation. Of these genes, four had high homology with known genes (MIDA1, PEBP2 beta, phosphatidylserine synthase 2 and SKAP55) and six fragments were new sequence tags of unknown genes. This result may contribute to reveal the patho-physiological effects of toluene inhalation on rat brain. PMID:17584516

Ikematsu, Kazuya; Tsuda, Ryouichi; Tsuruya, Shinichiro; Kubo, Shin-ichi; Nakasono, Ichiro

2007-06-20

434

Unusual swelling of HPC in toluene forming a microspherical domain structure that causes Christiansen scattering coloration.  

PubMed

The unusual swelling behavior of hydroxypropyl cellulose (HPC) by toluene is described. At temperatures as high as 100 degrees C, toluene molecules can enter the HPC film up to the weight fraction of 55%; however, they are segregated from the HPC matrix and form microspherical domains. The size of the spherical domain is approximately 4.5 microm in diameter on average. Such an unusual swelling behavior is due to the amphiphilic nature of the HPC; HPC polymers rearrange to contact their hydrophobic group with toluene and confine the toluene molecules in spherical domains. Because of the similarity in refractive indices of the toluene microspherical phase and the HPC continuum phase, the swollen film shows a beautiful scattering color that is called the Christiansen filter effect. PMID:19731958

Edo, Susumu; Okoshi, Kento; Kang, Sungmin; Tokita, Masatoshi; Kaneko, Tatsuo; Watanabe, Junji

2010-02-01

435

A Patient with Systemic Lupus Erythematosus Complicated by Neurological Symptoms of Toluene Poisoning  

PubMed Central

We report a patient with systemic lupus erythematosus complicated by toluene poisoning. She had erythema, alopecia, arthralgia, and various neurological symptoms. Laboratory findings showed leukocytopenia, low levels of complements, and anti-dsDNA antibody. However, normal interleukin-6 level and IgG index of cerebrospinal fluid and brain magnetic resonance imaging and single photon emission computed tomography findings suggested that her neurological symptoms were caused by metabolic disorder but not neuropsychiatric systemic lupus erythematosus. Erythema, alopecia, and arthralgia improved rapidly after administration of prednisolone and tacrolimus, whereas neurological symptoms improved only gradually. Because of a history of exposure to toluene, her neurological symptoms were considered to be due to toluene poisoning. The differentiation of toluene poisoning from neuropsychiatric systemic lupus erythematosus based on symptoms is difficult because both induce various neuropsychiatric disorders. Laboratory findings of cerebrospinal fluid, radiological findings, and medical interview were useful for differentiation of toluene poisoning from neuropsychiatric systemic lupus erythematosus.

Takeuchi, Tohru; Makino, Shigeki; Hanafusa, Toshiaki

2013-01-01

436

Modeling the toxicokinetics of 24-hour toluene exposure in rats, impact of activity patterns and enzyme induction  

EPA Science Inventory

Toluene, a solvent used in numerous consumer and industrial applications, exerts its critical effects on the brain and nervous system following inhalation exposure. Our previously published PBPK model successfully predicted toluene concentrations in blood and brain over a range o...

437

Metabolite Alterations in Basal Ganglia Associated with Psychiatric Symptoms of Abstinent Toluene Users: A Proton MRS Study  

Microsoft Academic Search

Long-term toluene abuse causes a variety of psychiatric symptoms. However, little is known about abnormalities at the neurochemical level in the living human brain after long-term exposure to toluene. To detect neurochemical changes in the basal ganglia of subjects with a history of long-term toluene use, proton magnetic resonance spectroscopy (1H MRS) was performed in 12 abstinent toluene users and

Kiyokazu Takebayashi; Yoshimoto Sekine; Nori Takei; Yoshio Minabe; Haruo Isoda; Hiroyasu Takeda; Katsuhiko Nishimura; Kazuhiko Nakamura; Katsuaki Suzuki; Yasuhide Iwata; Harumi Sakahara; Norio Mori

2004-01-01

438

Electrical Properties of Sand-Clay Mixtures Containing Trichloroethylene and Ethanol  

SciTech Connect

A series of laboratory experiments, including the measurement of electrical properties and permeability, were performed on carefully characterized sand-clay mixtures. Different mixtures and configurations of quartz sand and 0 to 10% Na-montmorillonite clay were investigated using solutions of NaCl, CaCl{sub 2}, and deionized water. Samples containing 10% distributed clay were also studied using fluids containing 20 and 500 ppm trichloroethylene (TCE). Electrical properties were measured at frequencies between 10{sup 6} and 10{sup -2} Hz using the four-electrode method and Ag-AgCl inner electrodes on saturated samples at room temperature and 412 kPa confining pressure, corresponding to a soil depth of 15 to 20 m. Our results show that the addition of TCE has a small effect on electrical resistivity, with resistivity increasing with the addition of TCE. The influence of TCE on the electrical properties was most prominent in plots of loss tangent as a function of frequency. A loss tangent peak occurred at {approx}200 Hz. The height of the peak and the peak frequency both decrease with the addition of TCE. Further experiments were performed on samples containing a distinct clay layer parallel to current flow. Electrical properties were measured on water saturated samples and as a mixture of ethanol and water (80:20) was flowed through the sample. Resistivity increased by about a factor of four as the ethanol mixture replaced the water solution. Non-destructive x-ray imaging of the sample at various stages of dewatering indicates a decrease in the thickness of the clay layer with increasing number of pore volumes of ethanol-water flowed. Our results showed that electrical measurements are a useful tool for characterizing porous rocks and soils and that it is feasible to remotely detect the presence and follow the transport of contaminants such as TCE in the subsurface.

Roberts, J J; Wildenschild, D

2001-12-04

439

Thermodynamic investigation of trichloroethylene adsorption in water-saturated microporous adsorbents  

SciTech Connect

Adsorption of trichloroethylene (TCE) in adsorbents containing hydrophilic and hydrophobic micropores was investigated in order to determine the mechanisms responsible for TCE adsorption on mineral solids. A high-pressure liquid chromatography method was used to measure TCE adsorption isotherms on three microporous adsorbents. Silica gel and zeolite type NaX were used as hydrophilic model adsorbents, and hexamethyldisilazane (HMDS)-treated silica gel was used as a model hydrophobic adsorbent. Batch uptake and desorption isotherms were also measured on the hydrophilic silica gel. Uptake of TCE by all three adsorbents was linear over the concentration range investigated. However, the silica gel desorption isotherm was highly nonlinear, as indicated by its Freundlich isotherm exponent of 0.58. Capillary phase separation into hydrophobic micropores was postulated as being responsible for the isotherm hysteresis. Supporting this hypothesis was the conformance of the TCE adsorption isotherm to Dubinin-Radushkevitch volume filling of micropores theory. The enthalpies for TCE adsorption on all three solids were determined by van't Hoff analysis of distribution coefficients measured over a temperature range from 5 to 90 C. The TCE adsorption enthalpies on the silica gel and HMDS silica gel were exothermic, but on the zeolite adsorption was endothermic. High exothermic adsorption enthalpies on the silica gel adsorbents indicated that TCE adsorption was occurring in hydrophobic micropores, and that adsorption on surfaces with large radii of curvature contributed only minimally to the total uptake. This indicates that the predominant mechanism for TCE adsorption on these mineral solids is not partitioning into the vicinal water layer.

Farrell, J.; Hauck, B.; Jones, M.

1999-08-01

440

New perspectives on the cancer risks of trichloroethylene, its metabolites, and chlorination by-products  

SciTech Connect

Scientific developments in the 1990`s have important implications for the assessment of cancer risks posed by exposures to trichloroethylene (TCE). These new developments include: epidemiological studies; experimental studies of TCE carcinogenicity, metabolism and metabolite carcinogenicity; applications of new physiologically based pharmacokinetic (PBPK) models for TCE; and new pharmacodynamic data obtained for TCE and its rhetabolites. Following a review of previous assessments of TCE carcinogenicity, each of these new sets of developments is summarized. The new epidemiological data do not provide evidence of TCE carcinogenicity in humans, and the new pharmacodynamic data support the hypothesis that TCE carcinogenicity is caused by TCE-induced cytotoxicity. Based on this information, PBPK-based estimates for likely no-adverse effect levels (NOAELs) for human exposures to TCE are calculated to be 16 ppb for TCE in air respired 24 hr/day, and 210 ppb for TCE in drinking water. Cancer risks of zero are predicted for TCE exposures below these calculated NOAELs. For comparison, hypothetical cancer risks posed by lifetime ingestive and multiroute household exposures to TCE in drinking water, at the currently enforced Maximum Contaminant Level (MCL) concentration of 5 ppb are extrapolated from animal bioassay data using a conservative, linear dose-response model. These TCE-related risks are compared to corresponding ones associated with concentrations of chlorination by-products (CBP) in household water. It is shown that, from the standpoint of comparative hypothetical cancer risks, based on conservative linear dose-response extrapolations, there would likely be no health benefit, and more likely a possible health detriment, associated with any switch from a household water supply containing <375 ppb TCE to one containing CBP at levels corresponding to the currently proposed 80-ppb MCL for total trihalomethanes.

Bogen, K.T. [Lawrence Livermore National Lab., CA (United States); Slone, T.; Gold, L.S.; Manley, N.; Revzan, K. [Lawrence Berkeley Lab., CA (United States)

1994-12-08

441

Interactive effects between trichloroethylene and pesticides at metabolic and genetic level in mice.  

PubMed Central

A combined cytogeneticurine metabolite analysis approach was used to assess potential interactive effects between Fenarimol (FN), a fungicide, and trichloroethylene (TRI), a halogenated solvent. FN was demonstrated to selectively induce P450-2B1 isoforms in different organs of treated mice. Since the rate of metabolism and the stereospecificity of metabolism are dependent on the types and amount of P450s available, FN might drastically alter the metabolic activation of a precarcinogen, such as TRI, and its toxicological consequences. Male CD1 mice were divided into untreated, vehicle control, and experimental groups. Animals of the latter groups were treated ip with 150 mg/kg bw FN in corn oil, 457 mg/kg bw TRI in corn oil, TRI plus FN separated by different time intervals. Bone marrow cells were harvested for determination of micronuclei (MN) frequencies in polychromatic erythrocytes (PCE). The presence of the known metabolite of TRI, trichloroethanol (TCE), was quantitated in collected urine by gas chromatography using an electron-capture detector. Linear regression analysis shows that MN frequency by TRI is correlated with TCE concentration in urine. Observed potentiation of genotoxicity of TRI by FN pretreatment (1 hr before TRI treatment) apparently reflects changes in the spectra of enzymes involved in TRI metabolism, and altered toxicokinetic, as witnessed by the 20% difference in TCE excretion from combined treated mice. However, no increased genetic or metabolic effects were observed when FN was administered 3 hr before TRI. No significant interactive effects were observed at a genetic level when FN was administered 1 hr and 3 hr after TRI whereas a 33 to 47% loss in TCE excretion was recorded.(ABSTRACT TRUNCATED AT 250 WORDS)

Hrelia, P; Maffei, F; Vigagni, F; Fimognari, C; Flori, P; Stanzani, R; Cantelli Forti, G

1994-01-01

442

Coupling of zero valent iron and biobarriers for remediation of trichloroethylene in groundwater.  

PubMed

This study attempted to construct a three series barrier system to treat high concentrations of trichloroethylene (TCE; 500 mg/L) in synthetic groundwater. The system consisted of three reactive barriers using iron fillings as an iron-based barrier in the first column, sugarcane bagasse mixed with anaerobic sludge as an anaerobic barrier in the second column, and a biofilm coated on oxygen carbon inducer releasing material as an aerobic barrier in the third column. In order to evaluate the extent of removal of TCE and its metabolites in the aquifer down gradient of the barrier system, a fourth column filled with sand was applied. Residence time of the system was investigated by a bromide tracer test. The results showed that residence time in the column system of the control set and experimental set were 23.62 and 29.99 days, respectively. The efficiency of the three series barrier system in removing TCE was approximately 84% in which the removal efficiency of TCE by the iron filling barrier, anaerobic barrier and aerobic barrier were 42%, 16% and 25%, respectively, cis-Dichloroethylene (cis-DCE), vinyl chloride (VC), ethylene and chloride ions were observed as metabolites following TCE degradation. The presence of chloride ions in the effluent from the column system indicated the degradation of TCE. However, cis-DCE and VC were not fully degraded by the proposed barrier system which suggested that another remediation technology after the barrier treatment such as air sparging and adsorption by activated carbon should be conducted. PMID:21793396

Teerakun, Mullika; Reungsang, Alissara; Lin, Chien-Jung; Liao, Chih-Hsiang

2011-01-01

443

Persulfate oxidation of trichloroethylene with and without iron activation in porous media.  

PubMed

In situ chemical oxidation with persulfate anion (S2O82*) is a viable technique for remediation of groundwater contaminants such as trichloroethylene (TCE). An accelerated reaction using S2O82* to destroy TCE can be achieved via chemical activation with ferrous ion to generate sulfate radicals (SO4*)(E degrees =2.6 V). The column study presented here simulates persulfate oxidation of TCE in porous media (glass beads and a sandy soil). Initial experiments were conducted to investigate persulfate transport in the absence of TCE in the column. The persulfate flushing exhibited a longer residence time and revealed a moderate persulfate interaction with soils. In TCE treatment experiments, the results indicate that the water or persulfate solution would push dissolved TCE from the column. Therefore, the effluent TCE concentration gradually increased to a maximum when about one pore volume was replaced with the flushing solution in the column. The presence of Fe2+ concentration within the column caused a quick drop in effluent TCE concentration and more TCE degradation was observed. When a TCE solution was flushing through the soil column, breakthrough of TCE concentration in the effluent was relatively slow. In contrast, when the soil column was flushed with a mixed solution of persulfate and TCE, persulfate appeared to preferentially oxidize soil oxidizable matter rather than TCE during transport. Hence, persulfate oxidation of soil organics may possibly reduce the interaction between TCE and soil (e.g., adsorption) and facilitate the transport of TCE through soil columns resulting in faster breakthrough. PMID:17692892

Liang, Chenju; Lee, I-Ling; Hsu, I-Yuang; Liang, Ching-Ping; Lin, Yu-Ling

2007-08-10

444

Molecular mechanism of trichloroethylene-induced hepatotoxicity mediated by CYP2E1  

SciTech Connect

Cytochrome P450 (CYP) 2E1 was suggested to be the major enzyme involved in trichloroethylene (TRI) metabolism and TRI-induced hepatotoxicity, although the latter molecular mechanism is not fully understood. The involvement of CYP2E1 in TRI-induced hepatotoxicity and its underlying molecular mechanism were studied by comparing hepatotoxicity in cyp2e1{sup +/+} and cyp2e1{sup -/-} mice. The mice were exposed by inhalation to 0 (control), 1000, or 2000 ppm of TRI for 8 h a day, for 7 days, and TRI-hepatotoxicity was assessed by measuring plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and histopathology. Urinary metabolites of trichloroethanol and trichloroacetic acid (TCA) were considerably greater in cyp2e1{sup +/+} compared to cyp2e1{sup -/-} mice, suggesting that CYP2E1 is the major P450 involved in the formation of these metabolites. Consistent with elevated plasma ALT and AST activities, cyp2e1{sup +/+} mice in the 2000 ppm group showed histopathological inflammation. TRI significantly upregulated PPAR{alpha}, which might function to inhibit NF{kappa}B p50 and p65 signalling. In addition, TRI-induced NF{kappa}B p52 mRNA, and significantly positive correlation between NF{kappa}B p52 mRNA expression and plasma ALT activity levels were observed, suggesting the involvement of p52 in liver inflammation. Taken together, the current study directly demonstrates that CYP2E1 was the major P450 involved in the first step of the TRI metabolism, and the metabolites produced may have two opposing roles: one inducing hepatotoxicity and the other protecting against the toxicity. Intermediate metabolite(s) from TRI to chloral hydrate produced by CYP2E1-mediated oxidation may be involved in the former, and TCA in the latter.

Ramdhan, Doni Hikmat; Kamijima, Michihiro; Yamada, Naoyasu; Ito, Yuki; Yanagiba, Yukie; Nakamura, Daichi; Okamura, Ai; Ichihara, Gaku [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine (Japan); Aoyama, Toshifumi [Department of Metabolic Regulation, Institute of Aging and Adaptation, Shinshu University Graduate School of Medicine (Japan); Gonzalez, Frank J. [Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, MD (United States); Nakajima, Tamie [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine (Japan)], E-mail: tnasu23@med.nagoya-u.ac.jp

2008-09-15

445

Flux-based assessment at a manufacturing site contaminated with trichloroethylene.  

PubMed

Groundwater and contaminant fluxes were measured, using the passive flux meter (PFM) technique, in wells along a longitudinal transect passing approximately through the centerline of a trichloroethylene (TCE) plume at a former manufacturing plant located in the Midwestern US. Two distinct zones of hydraulic conductivity were identified from the measured groundwater fluxes; a 6-m-thick upper zone ( approximately 7 m to 13 m below the ground surface or bgs) with a geometric mean Darcy flux (q(0)) of 2 cm/day, and a lower zone ( approximately 13 m to 16.5m bgs) with a q(0) approximately 15 cm/day; this important hydrogeologic feature significantly impacts any remediation technology used at the site. The flux-averaged TCE concentrations estimated from the PFM results compared well with existing groundwater monitoring data. It was estimated that at least 800 kg of TCE was present in the source zone. The TCE mass discharge across the source control plane (85 m x 38 m) was used to estimate the "source strength" ( approximately 365 g/day), while mass discharges across multiple down-gradient control planes were used to estimate the plume-averaged, TCE degradation rate constant (0.52 year(-1)). This is close to the rate estimated using the conventional centerline approach (0.78 year(-1)). The mass discharge approach provides a more robust and representative estimate than the centerline approach since the latter uses only data from wells along the plume centerline while the former uses all wells in the plume. PMID:16581154

Basu, Nandita B; Rao, P S C; Poyer, Irene C; Annable, M D; Hatfield, K

2006-04-03

446

Identification of antigenic proteins associated with trichloroethylene-induced autoimmune disease by serological proteome analysis  

SciTech Connect

Although many studies indicated that trichloroethylene (TCE) could induce autoimmune diseases and some protein adducts were detected, the proteins were not identified and mechanisms remain unknown. To screen and identify autoantigens which might be involved in TCE-induced autoimmune diseases, three groups of sera were collected from healthy donors (I), patients suffering from TCE-induced exfoliative dermatitis (ED) (II), and the healed ones (III). Serological proteome analysis (SERPA) was performed with total proteins of TCE-treated L-02 liver cells as antigen sources and immunoglobins of the above sera as probes. Highly immunogenic spots (2-fold or above increase compared with group I) in group II and III were submitted to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and tandem mass spectrometry sequencing. Western blot analysis was followed using commercial antibodies and individual serum. Six proteins were identified. Among them, Enoyl Coenzyme A hydratase peroxisoma 1 and lactate dehydrogenase B only showed stronger immunogenicity for group II sera, while Purine nucleoside phosphorylase, ribosomal protein P0 and proteasome activator subunit1 isoform1 also showed stronger immunogenicity for group III sera. Noteworthy, NM23 reacted only with group II sera. Western blot analysis of NM23 expression indicated that all of the individual serum of group II showed immune activity, which confirmed the validity of SERPA result. These findings revealed that there exist autoantibodies in group II and III sera. Besides, autoantibodies of the two stages of disease course were different. These autoantigens might serve as biomarkers to elucidate mechanisms underlying TCE toxicity and are helpful for diagnosis, therapy and prognosis of TCE-induced autoimmune diseases.

Liu Jianjun; Xing Xiumei; Huang Haiyan; Jiang Yingzhi; He Haowei; Xu Xinyun; Yuan Jianhui; Zhou Li; Yang Linqing [Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, No. 21, Rd 1st Tianbei, 518020 Shenzhen (China); Zhuang Zhixiong, E-mail: bio-research@hotmail.co [Key Laboratory of Modern Toxicology of Shenzhen, Shenzhen Center for Disease Control and Prevention, No. 21, Rd 1st Tianbei, 518020 Shenzhen (China)

2009-11-01

447

Impact of nanoscale zero valent iron on geochemistry and microbial populations in trichloroethylene contaminated aquifer materials.  

PubMed

Nanoscale zerovalent iron (NZVI) particles are a promising technology for reducing trichloroethylene (TCE) contamination in the subsurface. Prior to injecting large quantities of nanoparticles into the groundwater it is important to understand what impact the particles will have on the geochemistry and indigenous microbial communities. Microbial populations are important not only for nutrient cycling, but also for contaminant remediation and heavy metal immobilization. Microcosms were used to determine the effects of NZVI addition on three different aquifer materials from TCE contaminated sites in Alameda Point, CA, Mancelona, MI, and Parris Island, SC. The oxidation and reduction potential of the microcosms consistently decreased by more than 400 mV when NZVI was added at 1.5 g/L concentrations. Sulfate concentrations decreased in the two coastal aquifer materials, and methane was observed in the presence of NZVI in Alameda Point microcosms, but not in the other two materials. Denaturing gradient gel electrophoresis (DGGE) showed significant shifts in Eubacterial diversity just after the Fe(0) was exhausted, and quantitative polymerase chain reaction (qPCR) analyses showed increases of the dissimilatory sulfite reductase gene (dsrA) and Archaeal 16s rRNA genes, indicating that reducing conditions and hydrogen created by NZVI stimulate both sulfate reducer and methanogen populations. Adding NZVI had no deleterious effect on total bacterial abundance in the microcosms. NZVI with a biodegradable polyaspartate coating increased bacterial populations by an order of magnitude relative to controls. The lack of broad bactericidal effect, combined with the stimulatory effect of polyaspartate coatings, has positive implications for NZVI field applications. PMID:20350000

Kirschling, Teresa L; Gregory, Kelvin B; Minkley, Edwin G; Lowry, Gregory V; Tilton, Robert D

2010-05-01

448

Trichloroethylene biodegradation by mesophilic and psychrophilic ammonia oxidizers and methanotrophs in groundwater microcosms.  

PubMed Central

This study investigated the efficiency of methane and ammonium for stimulating trichloroethylene (TCE) biodegradation in groundwater microcosms (flasks and batch exchange columns) at a psychrophilic temperature (12 degrees C) typical of shallow aquifers in the northern United States or a mesophilic temperature (24 degrees C) representative of most laboratory experiments. After 140 days, TCE biodegradation rates by ammonia oxidizers and methanotrophs in mesophilic flask microcosms were similar (8 to 10 nmol day-1), but [14C]TCE mineralization (biodegradation to 14CO2) by ammonia oxidizers was significantly greater than that by methanotrophs (63 versus 53%). Under psychrophilic conditions, [14C]TCE mineralization in flask systems by ammonia oxidizers and methanotrophs was reduced to 12 and 5%, respectively. In mesophilic batch exchange columns, average TCE biodegradation rates for methanotrophs (900 nmol liter-1 day-1) were not significantly different from those of ammonia oxidizers (775 nmol liter-1 day-1). Psychrophilic TCE biodegradation rates in the columns were similar with both biostimulants and averaged 145 nmol liter-1 day-1. Methanotroph biostimulation was most adversely affected by low temperatures. At 12 degrees C, the biodegradation efficiencies (TCE degradation normalized to microbial activity) of methanotrophs and ammonia oxidizers decreased by factors of 2.6 and 1.6, respectively, relative to their biodegradation efficiencies at 24 degrees C. Collectively, these experiments demonstrated that in situ bioremediation of TCE is feasible at the psychrophilic temperatures common in surficial aquifers in the northern United States and that for such applications biostimulation of ammonia oxidizers could be more effective than has been previously reported.

Moran, B N; Hickey, W J

1997-01-01

449

Distribution of c-Fos immunoreactivity in the rat brain following abuse-like toluene vapor inhalation  

Microsoft Academic Search

Inhalation of vapors from toluene-containing products results in euphoria accompanied by a variety of cognitive impairments and motor dysfunctions. The profound behavioral changes observed during and following toluene inhalation suggest changes in the activity of cells in potentially many brain regions; however, a comprehensive assessment of the neuroanatomical structures activated by toluene vapor has not been completed. Thus in the

Kristina E. Perit; Jimmie M. Gmaz; J. D. Caleb Browne; Brittany A. Matthews; Mary Beth F. Dunn; Linda Yang; Tanya Raaphorst; Paul E. Mallet; Bruce E. McKay

450

Response of solvent-exposed printers and unexposed controls to six-hour toluene exposure.  

PubMed

The acute effects of toluene were studied in 43 male printers and 43 control subjects matched according to sex, age, educational level, and smoking habits. The mean age of the subjects was 36 (range 29-50) years. The printers had been exposed to solvents for 9 to 25 years during employment at flexo and rotogravure printing plants, while the controls had no history of solvent exposure. Each subject was exposed once in a climate chamber to either 100 ppm of toluene or clean air for 6.5 h preceded by a 1-h acclimatization period. The effects of toluene were measured from subjective votes with linear analogue rating scales on 16 items, and on the performance of 10 different tests measuring psychomotor skills, perceptual skills, and vigilance. Exposure to 100 ppm of toluene compared with exposure to clean air caused discomfort with complaints of low air quality, strong odor, fatigue, sleepiness, a feeling of intoxication, and irritation of the eyes, nose and throat. Furthermore, the subjects exposed to toluene showed decreased manual dexterity, decreased color discrimination, and decreased accuracy in visual perception. There was no significant difference in the effects of toluene on printers compared to those of toluene on controls, but tendencies toward a greater sensitivity were seen for the printers in two tests. PMID:4059890

Baelum, J; Andersen, I B; Lundqvist, G R; Mølhave, L; Pedersen, O F; Vaeth, M; Wyon, D P

1985-08-01

451

Optimizing nutrient supply in a rotatory-switching biofilter for toluene vapor treatment.  

PubMed

The influence of nutrient conditions on the degradation of toluene vapor in a rotatory-switching biofilter (RSB) was investigated. The biofilter consists of four segments connected in series, each with a packing layer made of polyvinyl formal. The influent airstreams including toluene vapors were passed through segments 1-3 as up-flow with a toluene concentration of 0.9-1.2 g m(-3) and with an empty-bed retention time of 26-52 sec. Nutrient solutions were fed to all packed segments once a day by means of immersion. The nutrient solution was used repeatedly and replenished by the addition of (NH4)2SO4. The result at 155 days showed nitrogen depletion was particularly obvious and the lack of nitrogen affected toluene removal. By adding 161 g of nitrogen solution per volumetric cubic meter of reactor, toluene removal efficiency was immediately increased to greater than 99%. With long-term biofilter operation, 21%-32% of ammonium was utilized for nitrification because of the growth of nitrifying bacteria such as Nitrosomonas sp. Based on the carbon-nitrogen balance, the daily nitrogen demand for toluene removal was estimated 2.1 g day(-1) at a toluene load of 70 g m(-3) hr(-1). PMID:22616287

Morita, Yasutaka; Okunishi, Suguru; Higuchi, Takashi; Nakajima, Jun

2012-04-01

452

Reproductive endocrine effects of acute exposure to toluene in men and women  

PubMed Central

OBJECTIVES: Despite observation of adverse reproductive effects of toluene, including alterations of serum gonadotropins (luteinising hormone (LH) and follicle stimulating hormone (FSH)) in humans, little is known of the mechanism of toxicity. The hypothesis was tested that toluene acutely suppresses pulsatile gonadotropin secretion by measuring LH and FSH at frequent intervals during controlled exposure to toluene. METHODS: Women in the follicular and luteal phases of the menstrual cycle and men were randomised to inhale filtered air with or without 50 ppm toluene through a mouthpiece for 3 hours (19% of the OSHA permissible exposure limit). Blood was sampled by intravenous catheter at 20 minute intervals for 3 hours before, 3 hours during, and 3 hours after exposure. Plasma LH, FSH, and testosterone were measured. Pulse amplitude, pulse frequency, and mean concentrations of LH and FSH for each of the 3 hour periods before, during and after exposure to toluene versus sham exposure were calculated with the ULTRA pulse detection program and compared by analysis of variance (ANOVA) with repeated measures. RESULTS: In men mean concentrations of LH showed a significant interaction (p < 0.05) between exposure and sampling period, with a greater LH decline during exposure to toluene than sham exposure. However, there was no concomitant effect on testosterone concentrations. The LH pulse frequency of women in the luteal phase showed a trend towards a significant interaction between exposure and sampling period (p = 0.06), with a greater decline in pulse frequency during exposure to toluene than sham exposure. There were no other significant effects of exposure to toluene. CONCLUSIONS: Three hour exposure to 50 ppm toluene did not result in abnormal episodic LH or FSH secretion profiles, however, subtle effects on LH secretion in men and women in the luteal phase were found. The clinical relevance of these effects is unclear, indicating the need for further study of reproductive function in exposed workers.  

Luderer, U.; Morgan, M. S.; Brodkin, C. A.; Kalman, D. A.; Faustman, E. M.

1999-01-01

453

Binge toluene exposure in pregnancy and pre-weaning developmental consequences in rats.  

PubMed

Binge Toluene Exposure in Pregnancy and Pre-weaning Developmental Consequences in Rats. Bowen, S.E. and Hannigan, J.H. The persistent rate of abuse of inhaled organic solvents, especially among women of child-bearing age, raises the risk for teratogenic effects of maternal toluene abuse. In this study, timed-pregnant Sprague Dawley rats were exposed from Gestation Day (GD) 8 to GD20 to 12,000 or 8000 parts per million (ppm) toluene, or 0ppm (controls) for 30min twice daily, 60min total daily exposure. Pups were assessed from postnatal day (PN) 4 to PN21 using a developmental battery measuring growth (i.e., body weight), maturational milestones (e.g., eye opening & incisor eruption), and biobehavioral development (e.g., negative geotaxis & surface righting). Pups exposed in utero to 12,000ppm or 8000ppm toluene weighed significantly less than the non-exposed control pups beginning at PN4 and PN12 (respectively) until PN21. Toluene resulted in significant increases in an index of poor perinatal outcome, specifically a composite of malformations, defined "runting" and neonatal death. No significant delays were observed in reaching maturational milestones. The results reveal that brief, repeated, prenatal exposure to high concentrations of toluene can cause growth retardation and malformations in rats. A comparison of the present, conservative results with findings in previous studies implies that binge patterns of toluene exposure in pregnant rats modeling human solvent abuse can result in developmental and morphological deficits in offspring. These results do not exclude the possibility that maternal toxicity as well as teratogenic effects of toluene may contribute to outcomes. The results suggest that abuse of inhaled organic solvents like toluene may result in similar early developmental outcomes in humans. PMID:23597557

Bowen, Scott E; Hannigan, John H

2013-04-15

454

Toward cost-benefit analysis of acute behavioral effects of toluene in humans.  

PubMed

There is increasing interest in being able to express the consequences of exposure to potentially toxic compounds in monetary terms in order to evaluate potential cost-benefit relationships of controlling exposure. Behavioral effects of acute toluene exposure could be subjected to cost-benefit analysis if the effects of toluene were quantitatively compared to those of ethanol ingestion, which has been monetized for applied contexts. Behavioral effects of toluene and ethanol were quantified by meta-analysis of studies from the peer-reviewed literature describing their effects on choice reaction time (reaction time in a test requiring a subject to choose among two or more alternatives before responding). The internal doses of these compounds were estimated by a general physiological and toxicokinetic (GPAT) simulation from exposure parameters provided in the reports. The reported effects were converted to a common metric (proportion of baseline) and related to the estimated internal doses of toluene and ethanol, from which dose-effect equations were fitted. The estimated effect of toluene was compared to the estimated effect of ethanol on the same dependent variable by deriving a dose-equivalence equation (DEE) to express the dose of toluene as an equivalent dose of ethanol on the basis of equal effect magnitude. A nomogram was constructed by GPAT simulation to relate the environmental exposure concentration of toluene to the equivalent effect magnitude of a range of ethanol internal doses. Behavioral effects and their evaluation are determined by internal doses, which in turn are determined by a variety of variables. In addition to concentration and duration of exposure, which determine internal dose by pharmacokinetic processes, the activity level of exposed persons is a major factor. This analysis provides a continuous function of the consequences of toluene exposure expressed as ethanol-equivalent doses within confidence limits. The resulting function has the potential to estimate the monetary values of behavioral deficits caused by a range of exposures to toluene from existing monetized information on ethanol. PMID:15876216

Benignus, Vernon A; Bushnell, Philip J; Boyes, William K

2005-04-01

455

Transformation of microflora during degradation of gaseous toluene in a biofilter detected using PCR-DGGE.  

PubMed

A laboratory-scale biofiltration system, the rotatory-switching biofilter (RSB), was operated for 199 days using toluene as a model pollutant. The target gaseous pollutant for the biofiltration experiment was approximately 300 ppmv of toluene. Toluene removal efficiency (RE, %) was initially approximately 20% with a 247-ppmv concentration (0.9 g m(-3)) of toluene during the first 10 days. Although the RE decreased several times whenever nitrogen was consumed, it again reached almost 100% when the nitrogen source was in sufficient supply. Denaturing gradient gel electrophoresis (DGGE) analysis was employed to assess the transformation ofmicroflora during operation of the biofilter The results based on a 16S rRNA gene profile showed that the microbial community structure changed with operation time.