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1

Metabolism of trichloroethylene and tetrachloroethylene in human subjects.  

PubMed Central

A linear correlation exists between the trichloroethylene concentration in the work environments and the level of total trichloro compounds in the urine of the workers, as expressed by the equation: Gamma = 7.25=chi + 5.5, where Gamma is trichloroethylene in air (ppm) is Chi is total trichloro compounds in urine (mg/l). Trichloroethanol level is also linearly related to trichloroethylene concentration, while trichloroacetic acid level deviates from the linear relation when trichloroethylene level exceeds 50 ppm. In the case of tetrachloroethylene exposure, both trichloroethanol and trichloroacetic acid levels, and consequently the total trichloro compound level, reach a plateau at tetrachloroethylene level well below 100 ppm. The mean urinary biological half-life is 41 hr for trichloroethylene and 144 hr for tetrachloroethylene. The two values are the largest of the values so far obtained with organic solvents. The respiratory half-life is shorter than the urinary half-life, both in richloroethylene and in tetrachloroethylene. Applications of the urinalyses in clinical cases are described. In one case of trichlorethylene dependency, a longer urinary half-life of 73 hr was observed. An automated system is presented for the determination of total trichloro compounds in human urine. The system can analyze the samples at the rate of 20 samples per hour with an accuracy comparable to that of the time-consuming manual analysis.

Ikeda, M

1977-01-01

2

Degradation of trichloroethylene by toluene dioxygenase in whole-cell studies with Pseudomonas putida F1.  

PubMed Central

Toluene-induced cells of Pseudomonas putida F1 removed trichloroethylene from growth media at a significantly greater initial rate than the methanotroph Methylosinus trichosporium OB3b. With toluene-induced P. putida F1, the initial degradation rate varied linearly with trichloroethylene concentration over the range of 8 to 80 microM (1.05 to 10.5 ppm). At 80 microM (10.5 ppm) trichloroethylene and 30 degrees C, the initial rate was 1.8 nmol/min per mg of total cell protein, but the rate decreased rapidly with time. A series of mutant strains derived from P. putida F1 that are defective in the todC gene, which encodes the oxygenase component of toluene dioxygenase, failed to degrade trichloroethylene and to oxidize indole to indigo. A spontaneous revertant selected from a todC culture regained simultaneously the abilities to oxidize toluene, to form indigo, and to degrade trichloroethylene. The three isomeric dichloroethylenes were degraded by P. putida F1, but tetrachloroethylene, vinyl chloride, and ethylene were not removed from incubation mixtures.

Wackett, L P; Gibson, D T

1988-01-01

3

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

National Technical Information Service (NTIS)

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 de...

M. S. Shields S. O. Montgomery P. J. Chapman S. M. Cuskey P. H. Pritchard

1989-01-01

4

ADVANCED OXIDATION PROCESSES FOR TREATING GROUNDWATER CONTAMINATED WITH TCE (TRICHLOROETHYLENE) AND PCE (TETRACHLOROETHYLENE): LABORATORY STUDIES (JOURNAL VERSION)  

EPA Science Inventory

Oxidation of trichloroethylene (TCE) and tetrachloroethylene (PCE) with various dosages of ozone or ozone plus hydrogen peroxide was studied in laboratory experiments. The results show that hydrogen peroxide accelerates the oxidation of TCE and PCE by ozone. At peroxide-to-ozone ...

5

Potential of physiologically based pharmacokinetics to amalgamate kinetic data of trichloroethylene and tetrachloroethylene obtained in rats and man  

Microsoft Academic Search

A physiologically based pharmacokinetic model was used to amalgamate information obtained in rats and man by various routes of exposure to trichloroethylene (TRI) and tetrachloroethylene (TETRA). Since there have been no pharmacokinetic data on drinking water exposure, drinking water exposure to TRI was conducted in rats using 14C-TRI. Several partition coefficients of TRI and TETRA were also determined in the

A Koizumi

1989-01-01

6

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

7

Potential biomarkers of trichloroethylene and toluene exposure in Corbicula fluminea  

Microsoft Academic Search

Freshwater clams Corbicula fluminea were exposed in aquariums to four doses of trichloroethylene-TCE-(1.56 up to 100 mg\\/1) or toluene-TOL-(7.5 up to 60 mg\\/1) for 5 days. At the end of exposure, components of (de)toxification metabolism of phases I and II, parameters related to oxidative stress and propionylcholinesterase activity were assayed. Determination of TCE and TOL concentrations in water revealed an

Mary-Laure Vidal; Anne Bassères; Jean-François Narbonne

2001-01-01

8

Toluene-Degrading Bacteria Are Chemotactic towards the Environmental Pollutants Benzene, Toluene, and Trichloroethylene  

PubMed Central

The bioremediation of polluted groundwater and toxic waste sites requires that bacteria come into close physical contact with pollutants. This can be accomplished by chemotaxis. Five motile strains of bacteria that use five different pathways to degrade toluene were tested for their ability to detect and swim towards this pollutant. Three of the five strains (Pseudomonas putida F1, Ralstonia pickettii PKO1, and Burkholderia cepacia G4) were attracted to toluene. In each case, the response was dependent on induction by growth with toluene. Pseudomonas mendocina KR1 and P. putida PaW15 did not show a convincing response. The chemotactic responses of P. putida F1 to a variety of toxic aromatic hydrocarbons and chlorinated aliphatic compounds were examined. Compounds that are growth substrates for P. putida F1, including benzene and ethylbenzene, were chemoattractants. P. putida F1 was also attracted to trichloroethylene (TCE), which is not a growth substrate but is dechlorinated and detoxified by P. putida F1. Mutant strains of P. putida F1 that do not oxidize toluene were attracted to toluene, indicating that toluene itself and not a metabolite was the compound detected. The two-component response regulator pair TodS and TodT, which control expression of the toluene degradation genes in P. putida F1, were required for the response. This demonstration that soil bacteria can sense and swim towards the toxic compounds toluene, benzene, TCE, and related chemicals suggests that the introduction of chemotactic bacteria into selected polluted sites may accelerate bioremediation processes.

Parales, Rebecca E.; Ditty, Jayna L.; Harwood, Caroline S.

2000-01-01

9

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

10

Coupling transport and biodegradation of toluene and trichloroethylene in unsaturated soils  

NASA Astrophysics Data System (ADS)

Trichloroethylene (TCE), a common groundwater pollutant generally resistant to aerobic biodegradation, can be cometabolized in the presence of another compound such as toluene. The coupled transport and biodegradation of TCE and toluene was investigated and modeled in laboratory soil columns. Toluene biodegradation was linked to microbial growth using Monod kinetics, while TCE degradation was described using Michaelis-Menten kinetics modified to account for changing enzyme levels. Biodegradation of TCE was modeled as a mass fraction of the toluene degradation rate. Both growth and decay were incorporated into the equations to model microbial population dynamics. With the exception of the initial biomass, a single set of parameters to describe both degradation functions was obtained from independent soil batch experiments. Physical parameters were obtained from sterile soil columns. The initial biomass declined from the inlet to the outlet side of the chamber. Toluene was fully degraded in the soil column with the majority occurring closest to the inlet chamber. A substantial amount of TCE was not degraded because it diffused faster and was transformed at a lower rate than toluene.

El-Farhan, Y. H.; Scow, K. M.; de Jonge, L. W.; Rolston, D. E.; Moldrup, P.

1998-03-01

11

Biodegradation of trichloroethylene and toluene by indigenous microbial populations in soil.  

PubMed Central

The biodegradation of trichloroethylene (TCE) and toluene, incubated separately and in combination, by indigenous microbial populations was measured in three unsaturated soils incubated under aerobic conditions. Sorption and desorption of TCE (0.1 to 10 micrograms ml-1) and toluene (1.0 to 20 micrograms ml-1) were measured in two soils and followed a reversible linear isotherm. At a concentration of 1 micrograms ml-1, TCE was not degraded in the absence of toluene in any of the soils. In combination, both 1 microgram of TCE ml-1 and 20 micrograms of toluene ml-1 were degraded simultaneously after a lag period of approximately 60 to 80 h, and the period of degradation lasted from 70 to 90 h. Usually 60 to 75% of the initial 1 microgram of TCE ml-1 was degraded, whereas 100% of the toluene disappeared. A second addition of 20 micrograms of toluene ml-1 to a flask with residual TCE resulted in another 10 to 20% removal of the chemical. Initial rates of degradation of toluene and TCE were similar at 32, 25, and 18 degrees C; however, the lag period increased with decreasing temperature. There was little difference in degradation of toluene and TCE at soil moisture contents of 16, 25, and 30%, whereas there was no detectable degradation at 5 and 2.5% moisture. The addition of phenol, but not benzoate, stimulated the degradation of TCE in Rindge and Yolo silt loam soils, methanol and ethylene slightly stimulated TCE degradation in Rindge soil, glucose had no effect in either soil, and dissolved organic carbon extracted from soil strongly sorbed TCE but did not affect its rate of biodegradation.

Fan, S; Scow, K M

1993-01-01

12

Toluene-Degrading Bacteria Are Chemotactic towards the Environmental Pollutants Benzene, Toluene, and Trichloroethylene  

Microsoft Academic Search

The bioremediation of polluted groundwater and toxic waste sites requires that bacteria come into close physical contact with pollutants. This can be accomplished by chemotaxis. Five motile strains of bacteria that use five different pathways to degrade toluene were tested for their ability to detect and swim towards this pollutant. Three of the five strains (Pseudomonas putida F1, Ralstonia pickettii

REBECCA E. PARALES; JAYNA L. DITTY; CAROLINE S. HARWOOD

2000-01-01

13

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

2011-05-01

14

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

15

Activity-Dependent Enzymatic Assay for the Detection of Toluene-Oxidizing Bacteria Capable of Trichloroethylene Degradation  

NASA Astrophysics Data System (ADS)

Toluene-oxidizing bacteria produce enzymes that cometabolically degrade trichloroethylene (TCE). These inducible enzymes are produced only in the presence of certain aromatic substrates such as toluene or phenol. Recent laboratory studies have utilized analog chemical substrates to identify production of bacterial enzymes capable of degrading trichloroethylene. These analog substrates produce chromogenic and/or fluorescent products when biotransformed by the enzymes of interest. In this study, 3-hydroxyphenylacetylene (3-HPA) was identified as an activity-dependent enzymatic probe for the detection of three of the four known toluene oxygenase enzymes capable of TCE degradation. Laboratory studies were conducted using pure cultures of Burkholderia cepacia G4, Burkholderia pickettii PKO1, and Pseudomonas putida F1. Cell cultures grown on lactate (non-enzyme inducing) or lactate and toluene (inducing) were trapped trapped on black polycarbonate filters, exposed to 3-HPA, and examined for fluorescence using an epifluorescent microscope. Additionally, B. cepacia G4 cells were grown under the same conditions, but in the presence of mineral and basalt specimens to allow for bacterial attachment. The specimens were then exposed to 3-HPA and examined under an epifluorescent microscope. Our results demonstrate that cells induced for the production of oxygenase enzymes, both unattached and attached, are able to transform 3-HPA to a fluorescent product, although cells attached to geologic materials, such as basalt, take substantially longer to transform the probe. Cells grown under non-inducing conditions do not transform the probe, regardless of their attachment status. Additionally, well water samples taken from a TCE-contaminated aquifer were successfully assayed using the 3-HPA enzymatic probe. The development of this enzyme activity-dependent enzymatic assay provides a fast and reliable method to assess the potential for TCE and aromatic contaminant bioremediation.

Kauffman, M. E.; Kauffman, M. E.; Keener, W. K.; Watwood, M. E.; Lehman, R. M.

2001-12-01

16

BIOTRANSFORMATION OF TRICHLOROETHYLENE IN SOIL  

EPA Science Inventory

The organic contaminants that are most commonly detected in groundwater are low-molecular-weight, chlorinated aliphatic hydrocarbons such as trichloroethylene (TCE), tetrachloroethylene (PCE), 1,1,1-trichloroethane, carbon tetrachloride, and chloroform. The authors exposed unsatu...

17

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

18

Toxicological Profile for Tetrachloroethylene (Update).  

National Technical Information Service (NTIS)

Tetrachloroethylene has been found in at least 771 of the 1,430 current or former NPL sites. Tetrachloroethylene in a synthetic chemical that is widely used for dry cleaning of fabrics and for metal-degreasing operations. It is also used as a starting mat...

C. Eisenmann S. Yee-Wan

1997-01-01

19

Correlation of tetrachloroethylene in blood and in drinking water: A case of well water pollution  

SciTech Connect

Tetrachloroethylene has been widely used for the cleaning of cloth for many years. Currently, this chemical together with trichloroethylene (TRI) appears to be the most prevailing pollutant of ground water in various countries including Japan. While the biological monitoring of TETRA exposure is popular in occupational health, TETRA was seldom analyzed in the subjects exposed through the general environment. In the present report, a case of water pollution with TETRA is described in which up to 5 {mu}g/L TETRA was detected in the blood of the inhabitants in a area where well water was contaminated with TETRA.

Kido, Kazuhiro; Shiratori, Takehiko; Watanabe, Takao; Nakatsuka, Haruo; Ohashi, Mariko; Ikeda, Masayuki (Tohoku Univ. School of Medicine, Sendai (Japan))

1989-09-01

20

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...

21

Mutants of 'Pseudomonas cepacia' G4 Defective in Catabolism of Aromatic Compounds and Trichloroethylene.  

National Technical Information Service (NTIS)

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

M. S. Shields S. O. Montgomery S. M. Cuskey P. J. Chapman

1991-01-01

22

CONSTITUTIVE DEGRADATION OF TRICHLOROETHYLENE BY AN ALTERED BACTERIUM IN A GAS-PHASE BIOREACTOR  

EPA Science Inventory

Pseudomonas cepacia G4 expresses a unique toluene ortho-monooxygenase (Tom) that enables it to degrade toluene and trichloroethylene (TCE). ransposon mutants of G4 have been isolated that constitutively express Tom. wo fixed-film bioreactor designs were investigated for the explo...

23

HEALTH ASSESSMENT DOCUMENT FOR TETRACHLOROETHYLENE (PERCHLOROETHYLENE)  

EPA Science Inventory

Tetrachloroethylene (PERC) is believed to exert its adverse effects upon humans via metabolism by the liver. Concern that PERC is likely to be a human carcinogen is based upon the evidence of the National Cancer Institute bioassay, in which PERC induced a statistically significan...

24

Induction of rat liver drug-metabolizing enzymes by tetrachloroethylene  

Microsoft Academic Search

The effect of tetrachloroethylene on Phase I and II drug-metabolizing enzymes in rat liver was examined. Rats were treated orally with tetrachloroethylene daily for five days, at doses of 125, 250, 500, 1,000 and 2,000 mg\\/kg. The higher doses (>500 mg\\/kg) of tetrachloroethylene induced the hepatic microsomal 7-pentoxyresorufin O-depentylase and 7-benzyloxyresorufin O-debenzylase activities associated with the CYP2B subfamily. 7-ethoxyresorufin O-deethylase

N. Hanioka; H. Jinno; T. Toyo'oka; T. Nishimura; M. Ando

1995-01-01

25

Diverse manifestations of trichloroethylene.  

PubMed Central

Trichloroethylene, a solvent used in a variety of industrial settings for more than 60 years, has caused adverse health effects on the central and peripheral nervous system, the skin, liver, kidney, and heart. Three men have shown relatively unusual manifestations secondary to exposure to trichloroethylene in degreasing operations in the jewelry industry. Toxic encephalopathy, hepatitis, and carpal spasm occurred among young, healthy workers. Clinical and laboratory data, including measurement of urinary trichloroacetic acid concentrations, are presented.

McCunney, R J

1988-01-01

26

Diverse manifestations of trichloroethylene.  

PubMed

Trichloroethylene, a solvent used in a variety of industrial settings for more than 60 years, has caused adverse health effects on the central and peripheral nervous system, the skin, liver, kidney, and heart. Three men have shown relatively unusual manifestations secondary to exposure to trichloroethylene in degreasing operations in the jewelry industry. Toxic encephalopathy, hepatitis, and carpal spasm occurred among young, healthy workers. Clinical and laboratory data, including measurement of urinary trichloroacetic acid concentrations, are presented. PMID:3342194

McCunney, R J

1988-02-01

27

ACUTE TOXICITY OF TETRACHLOROETHYLENE AND TETRACHLOROETHYLENE WITH DIMETHYLFORMAMIDE TO RAINBOW TROUT (SALMO GAIRDNERI)  

EPA Science Inventory

In this study, two acute toxicity tests were conducted with tetrachloroethylene (TCE) using rainbow trout. DMF was used as an additive in one of the tests and was proportionally diluted with the toxicant. The 96 hr LC50 was 4.99 mg/l in the test without DMF and 5.84 mg/l for DMF ...

28

Development of genetically engineered bacteria for trichloroethylene degradation  

Microsoft Academic Search

The genes coding for toluene monooxygenase (TMO), an enzyme also capable of degrading trichloroethylene (TCE), from Pseudomonas mendocina KR1 were cloned into both narrow? and broad?host?range vectors and introduced into Escherichia coli and P. putida. TMO activity expressed by a number of strain\\/plasmid combinations was assayed by determining decreases in the fluorescence of indble. Degradation of TCE was investigated in

T. E. Ward; D. Bulmer; M. R. Walton; W. A. Apel

1998-01-01

29

Lactational transfer of tetrachloroethylene in rats.  

PubMed

Tetrachloroethylene (PCE) is a commonly used organic solvent and a suspected human carcinogen, reportedly transferred to human breast milk following inhalation exposure. Transfer of PCE to milk may represent a threat to the nursing infant. A physiologically based pharmacokinetic (PBPK) model was developed to quantitatively assess the transfer of inhaled PCE into breast milk and the consequent exposure of the nursing infant. The model was validated in lactating rats. Lactating Sprague-Dawley female rats were exposed via inhalation to PCE at concentrations ranging from 20-1000 ppm, and then returned to their nursing, 10- to 11-day-old pups. Tetrachloroethylene concentrations in the air, blood, milk, and tissue were determined by gas chromatography and compared to model predictions. The model described the distribution of inhaled PCE in maternal blood and milk, as well as the nursed pup's gastrointestinal tract, blood, and tissue. Several computer simulations of PCE distribution kinetics in exhaled air, blood, and milk of exposed human subjects were run and compared with limited human data available from the literature. It is concluded that the PBPK model successfully described the concentration of PCE in both lactating rats and humans. Although predictions vs. observations were good, the model slightly underpredicted the peak whole pup PCE concentration and underpredicted systemic clearance of PCE from the pup. PMID:8029506

Byczkowski, J Z; Fisher, J W

1994-06-01

30

Anaerobic biodegradation of alkylbenzenes and trichloroethylene in aquifer sediment down gradient of a sanitary landfill  

Microsoft Academic Search

The objective of this investigation was to evaluate the anaerobic biodegradability of benzene, toluene, ethylbenzene, ortho-, meta- and para-xylene (BTEX) and trichloroethylene (TCE) in aquifer sediment down gradient of an unlined landfill. The major organic contaminants identified in the shallow unconfined aquifer are cis-dichloroethylene (c-DCE) and toluene. The biodegradative potential of the contaminated aquifer was measured in three sets of

James J. Johnston; Robert C. Borden; Morton A. Barlaz

1996-01-01

31

Superfund Fact Sheet: Trichloroethylene.  

National Technical Information Service (NTIS)

The fact sheet describes trichloroethylene (TCE), a chemical that can be found in a variety of products, including some glues, paints and paint removers, and spot removers and cleaners. Explanations of how TCE can get into the body and how it can affect h...

1992-01-01

32

TRICHLOROETHYLENE (TCE) ISSUE PAPERS  

EPA Science Inventory

These issue papers are a part of EPA's effort to develop a trichloroethylene (TCE) human health risk assessment. These issue papers were developed by EPA to provide scientific and technical information to the National Academy of Sciences (NAS) for use in developing their advice ...

33

IRIS TOXICOLOGICAL REVIEW OF TETRACHLOROETHYLENE (PERCHLOROETHYLENE) (INTERAGENCY SCIENCE DISCUSSION DRAFT)  

EPA Science Inventory

EPA is releasing the draft report, Toxicological Review of Tetrachloroethylene (Perchloroethylene), that was distributed to Federal agencies and White House Offices for comment during the Science Discussion step of the IRIS Assessment...

34

KINETICS OF THE TRANSFORMATION OF TRICHLOROETHYLENE AND TETRACHLOROETHYLENE BY IRON SULFIDE. (R825958)  

EPA Science Inventory

The transformation of nine halogenated aliphatic compounds by 10 g/L (0.5 m2/L) FeS at pH 8.3 was studied in batch experiments. These compounds were as follows: pentachloroethane (PCA), 1,1,2,2- and 1,1,1,2-tetrachloroethanes (1122-TeCA and 1112-TeCA), 1,1,...

35

Induction of the tod operon by trichloroethylene in Pseudomonas putida TVA8  

SciTech Connect

Bioluminescence, mRNA levels, and toluene degradation rates in Pseudomonas putida TVA8 were measured as a function of various concentrations of toluene and trichloroethylene (TCE). TVA8 showed an increasing bioluminescence response to increasing TCE and toluene concentrations. Compared to uninduced TVA8 cultures, todC1 mRNA levels increased 11-fold for TCE-treated cultures and 13-fold for toluene-treated cultures. Compared to uninduced P. putida F1 cultures, todC1 mRNA levels increased 4,4-fold for TCE-induced cultures and 4.9-fold for toluene-induced cultures. Initial toluene degradation rates were linearly correlated with specific bioluminescence in TVA8 cultures.

Shingleton, J.T.; Applegate, B.M.; Nagel, A.C.; Bienkowski, P.R.; Sayler, G.S. [Univ. of Tennessee, Knoxville, TN (United States)

1998-12-01

36

Biodegradation of trichloroethylene and involvement of an aromatic biodegradative pathway.  

PubMed Central

Biodegradation of trichloroethylene (TCE) by bacterial strain G4 resulted in complete dechlorination of the compound, as indicated by the production of inorganic chloride. A component of the water from which strain G4 was isolated that was required for TCE degradation was identified as phenol. Strain G4 degraded TCE in the presence of chloramphenicol only when preinduced with phenol. Toluene, o-cresol. and m-cresol could replace the phenol requirement. Two of the inducers of TCE metabolism, phenol and toluene, apparently induced the same aromatic degradative pathway that cleaved the aromatic ring by meta fission. Cells induced with either phenol or toluene had similar oxidation rates for several aromatic compounds and had similar levels of catechol-2,3-dioxygenase. The results indicate that one or more enzymes of an inducible pathway for aromatic degradation in strain G4 are responsible for the degradation of TCE.

Nelson, M J; Montgomery, S O; Mahaffey, W R; Pritchard, P H

1987-01-01

37

40 CFR 469.22 - Specialized definitions.  

Code of Federal Regulations, 2013 CFR

...naphthalene 2 Nitrophenol phenol bis (2-ethylhexyl) phthalate tetrachloroethylene toluene trichloroethylene 2 Chlorophenol...Dichlorophenol 4 Nitrophenol pentachlorophenol di-n-butyl phthalate anthracene 1,2 Diphenylhydrazine isophorone butyl...

2013-07-01

38

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)...

39

IRIS Toxicological Review of Tetrachloroethylene (Perchloroethylene) (External Review Draft)  

EPA Science Inventory

EPA conducted a peer review of the scientific basis supporting the human health hazard and dose-response assessment of tetrachloroethylene that will appear on the Integrated Risk Information System (IRIS) database. Peer review is meant to ensure that science is used credibly and ...

40

Visual Contrast Sensitivity in Children Exposed to Tetrachloroethylene  

Microsoft Academic Search

This study examined relationships between indoor air, breath, and blood tetrachloroethylene (perc) levels and visual contrast sensitivity (VCS) among adult and child residents of buildings with or without a colocated dry cleaner using perc. Decreasing trends in proportions of adults or children with maximum VCS scores indicated decreased VCS at a single spatial frequency (12 cycles per degree [cpd]) among

Jan E. Storm; Kimberly A. Mazor; Kenneth M. Aldous; Benjamin C. Blount; Scott E. Brodie; Janet B. Serle

2011-01-01

41

Health Assessment Document for Tetrachloroethylene (Perchloroethylene) (Final Report)  

EPA Science Inventory

Tetrachloroethylene (PCE) is a volatile solvent with important commercial applications. It has been detected in the ambient air of a variety of urban and nonurban areas of the United States. It has less frequently been detected in water but has been monitored generally at levels ...

42

STATUS ASSESSMENT OF TOXIC CHEMICALS: TRICHLOROETHYLENE  

EPA Science Inventory

The production processes, uses, and properties of trichloroethylene are revealed in this report. The sources and amounts of trichloroethylene pollution are identified as well as the health effects and environmental significance. Current control technologies are identified, along ...

43

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

44

Rhizosphere Competitiveness of Trichloroethylene-Degrading, Poplar-Colonizing Recombinant Bacteria  

Microsoft Academic Search

Indigenous bacteria from poplar tree (Populus canadensis var. eugenei 'Imperial Carolina') and southern California shrub rhizospheres, as well as two tree-colonizing Rhizobium strains (ATCC 10320 and ATCC 35645), were engineered to express constitutively and stably toluene o-monooxygenase (TOM) from Burkhold- eria cepacia G4 by integrating the tom locus into the chromosome. The poplar and Rhizobium recombinant bacteria degraded trichloroethylene at

HOJAE SHIM; SADHANA CHAUHAN; DOOHYUN RYOO; KALLY BOWERS; STUART M. THOMAS; JOEL G. BURKEN; THOMAS K. WOOD

2000-01-01

45

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

PubMed

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. PMID:1892384

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

1991-07-01

46

Biodegradation of tetrachloroethylene in upflow anaerobic sludge blanket reactor  

Microsoft Academic Search

The laboratory study using upflow anaerobic sludge blanket (UASB) reactor in high strength wastewater containing tetrachloroethylene (PCE) was carried out to develop granular sludge in the presence of PCE (2 mg\\/l) and to assess the potential of UASB reactor in treating PCE containing wastewater. The granules of 0.25–4 mm size were observed after 82 days having mostly Methanothrix and Methanosarcina

S. M. Prakash; S. K. Gupta

2000-01-01

47

Human Health Effects of Tetrachloroethylene: Key Findings and Scientific Issues  

PubMed Central

Background: The U.S. Environmental Protection Agency (EPA) completed a toxicological review of tetrachloroethylene (perchloroethylene, PCE) in February 2012 in support of the Integrated Risk Information System (IRIS). Objectives: We reviewed key findings and scientific issues regarding the human health effects of PCE described in the U.S. EPA’s Toxicological Review of Tetrachloroethylene (Perchloroethylene). Methods: The updated assessment of PCE synthesized and characterized a substantial database of epidemiological, experimental animal, and mechanistic studies. Key scientific issues were addressed through modeling of PCE toxicokinetics, synthesis of evidence from neurological studies, and analyses of toxicokinetic, mechanistic, and other factors (tumor latency, severity, and background rate) in interpreting experimental animal cancer findings. Considerations in evaluating epidemiological studies included the quality (e.g., specificity) of the exposure assessment methods and other essential design features, and the potential for alternative explanations for observed associations (e.g., bias or confounding). Discussion: Toxicokinetic modeling aided in characterizing the complex metabolism and multiple metabolites that contribute to PCE toxicity. The exposure assessment approach—a key evaluation factor for epidemiological studies of bladder cancer, non-Hodgkin lymphoma, and multiple myeloma—provided suggestive evidence of carcinogenicity. Bioassay data provided conclusive evidence of carcinogenicity in experimental animals. Neurotoxicity was identified as a sensitive noncancer health effect, occurring at low exposures: a conclusion supported by multiple studies. Evidence was integrated from human, experimental animal, and mechanistic data sets in assessing adverse health effects of PCE. Conclusions: PCE is likely to be carcinogenic to humans. Neurotoxicity is a sensitive adverse health effect of PCE. Citation: Guyton KZ, Hogan KA, Scott CS, Cooper GS, Bale AS, Kopylev L, Barone S Jr, Makris SL, Glenn B, Subramaniam RP, Gwinn MR, Dzubow RC, Chiu WA. 2014. Human health effects of tetrachloroethylene: key findings and scientific issues. Environ Health Perspect 122:325–334;?http://dx.doi.org/10.1289/ehp.1307359

Hogan, Karen A.; Scott, Cheryl Siegel; Cooper, Glinda S.; Bale, Ambuja S.; Kopylev, Leonid; Barone, Stanley; Makris, Susan L.; Glenn, Barbara; Subramaniam, Ravi P.; Gwinn, Maureen R.; Dzubow, Rebecca C.; Chiu, Weihsueh A.

2014-01-01

48

Extraction of Tetrachloroethylene from Weathered Soils: A Comparison between Soxhlet Extraction and Microwave-Assisted Extraction  

Microsoft Academic Search

The inadvertent ingestion of contaminated soil can be an important source of xenobiotic exposure to the humans. Our study focuses on chlorinated hydrocarbons in soil, particularly tetrachloroethylene. Tetrachloroethylene is used for dry cleaning and textile processing, as a chemical intermediate and as a degreasing agent. It is also used for rubber coatings, solvent soaps, printing inks, adhesives, polishes, lubricants and

H. Chua

49

Health risk assessment of tetrachloroethylene (PCE) in California drinking water  

SciTech Connect

This document presents an assessment of the potential health risks associated with exposure to tetrachloroethylene (also known as perchloroethylene or PCE) dissolved in California drinking waters. A primary goal of this health-risk assessment is to evaluate dose-response relationships for observed and potential toxic end points of PCE in order to define dose rates that can be used to establish standards that will protect members of the general public from adverse health effects resulting solely from water-based exposures to PCE. We also analyze the extent of human exposures attributable to PCE-contaminated ground water in California.

Bogen, K.T.; Hall, L.C.; McKone, T.E.; Layton, D.W.; Patton, S.E.

1987-04-10

50

Ultrasonic and microwave desulfurization of coal in tetrachloroethylene  

SciTech Connect

The extractive desulfurization of four high sulfur coals from China were promoted with ultrasonic and microwave in tetrachloroethylene organic solvents. It was shown that the joint promotion with ultrasonic and microwave had an active effect on extractive desulfurization. The rate of desulfurization increased with the increase of time in ultrasonic field as well as with the power of ultrasonic, but declined with the increase of the particle size of coal. The rate of desulfurization was not identical for different coal, which was perhaps related to the existed forms of organic sulfur in coal.

Mi, J.; Ren, J.; Wang, J.C.; Bao, W.R. [Taiyuan University of Technology, Taiyuan (China)

2007-07-01

51

SUMMARY REPORT OF THE PEER REVIEW WORKSHOP ON THE NEUROTOXICITY OF TETRACHLOROETHYLENE (PERCHLOROETHYLENE) DISCUSSION PAPER  

EPA Science Inventory

The report, Summary Report of the Peer Review Workshop on the Neurotoxicity of Tetrachloroethylene (Perchloroethylene) Discussion , summarizes the discussions at a February 25, 2004, workshop that brought together recognized scientific experts to engage in a public discussi...

52

RESPONSE TO ISSUES AND DATA SUBMISSIONS ON THE CARCINOGENICITY OF TETRACHLOROETHYLENE (PERCHLOROETHYLENE)  

EPA Science Inventory

The scientific debate over the potential carcinogenicity of tetrachloroethylene (perchloroethylene, perc, PCE) spans several years. his document reviews the issues considered by the EPA's Science Advisory Board (SAB) during its review of the Draft Addendum to the Health Assessmen...

53

THE ADDITION OF CYCLIC ETHERS TO TETRACHLOROETHYLENE BY THE $gamma$RAY IRRADIATION  

Microsoft Academic Search

The radiation-induced addition reaction between tetrachloroethylene and ; cyclic ethers, tetrahydrofuran and paradioxane, was studied. In a glass ampule ; tetrachloroethylene and cyclic ether were placed and the ampule was deaerated, ; sealed, and then irradiated with gamma rays at a dose rate of 1.2 to 6.0 x 10\\/sup ; 4\\/ r\\/hr at room temperature. The reaction mixture was distilled

T. Matsuda; T. Yumoto; K. Iseda

1963-01-01

54

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...

55

Ethanol-Induced Changes in Trichloroethylene Toxicity.  

National Technical Information Service (NTIS)

This project was aimed at determining the extent to which the metabolism of trichloroethylene (TCE) to trichloroacetate (TCA) was responsible for its hepatotoxic effects in rodents. Originally ethanol co-administration was to be used to selectively decrea...

R. J. Bull

1988-01-01

56

Cometabolic degradation of trichloroethylene by Burkholderia cepacia G4 with poplar leaf homogenate.  

PubMed

Trichloroethylene (TCE), a chlorinated organic solvent, is one of the most common and widespread groundwater contaminants worldwide. Among the group of TCE-degrading aerobic bacteria, Burkholderia cepacia G4 is the best-known representative. This strain requires the addition of specific substrates, including toluene, phenol, and benzene, to induce the enzymes to degrade TCE. However, the substrates are toxic and introducing them into the soil can result in secondary contamination. In this study, poplar leaf homogenate containing natural phenolic compounds was tested for the ability to induce the growth of and TCE degradation by B. cepacia G4. The results showed that the G4 strain could grow and degrade TCE well with the addition of phytochemicals. The poplar leaf homogenate also functioned as an inducer of the toluene-ortho-monooxygenase (TOM) gene in B. cepacia G4. PMID:24992516

Kang, Jun Won; Doty, Sharon Lafferty

2014-07-01

57

Prenatal and Early Childhood Exposure to Tetrachloroethylene and Adult Vision  

PubMed Central

Background: Tetrachloroethylene (PCE; or perchloroethylene) has been implicated in visual impairments among adults with occupational and environmental exposures as well as children born to women with occupational exposure during pregnancy. Objectives: Using a population-based retrospective cohort study, we examined the association between prenatal and early childhood exposure to PCE-contaminated drinking water on Cape Cod, Massachusetts, and deficits in adult color vision and contrast sensitivity. Methods: We estimated the amount of PCE that was delivered to the family residence from participants’ gestation through 5 years of age. We administered to this now adult study population vision tests to assess acuity, contrast sensitivity, and color discrimination. Results: Participants exposed to higher PCE levels exhibited lower contrast sensitivity at intermediate and high spatial frequencies compared with unexposed participants, although the differences were generally not statistically significant. Exposed participants also exhibited poorer color discrimination than unexposed participants. The difference in mean color confusion indices (CCI) was statistically significant for the Farnsworth test but not Lanthony’s D-15d test [Farnsworth CCI mean difference = 0.05, 95% confidence interval (CI): 0.003, 0.10; Lanthony CCI mean difference = 0.07, 95% CI: –0.02, 0.15]. Conclusions: Prenatal and early childhood exposure to PCE-contaminated drinking water may be associated with long-term subclinical visual dysfunction in adulthood, particularly with respect to color discrimination. Further investigation of this association in similarly exposed populations is necessary.

Getz, Kelly D.; Janulewicz, Patricia A.; Rowe, Susannah; Weinberg, Janice M.; Winter, Michael R.; Martin, Brett R.; Vieira, Veronica M.; White, Roberta F.

2012-01-01

58

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

59

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

2013-01-01

60

Toluene removal biofilter modeling.  

PubMed

On the basis of the model proposed by De Visscher and Van Cleemput for methane oxidation in landfill cover soils, simulation models for biofiltration of toluene-contaminated air were performed for biofilters with or without substrate inhibition and operated at constant or varying airflow rates. The toluene oxidizing activity (V(max)) expressions of the derived models clearly indicate that V(max) is not a constant along a biofilter height. The equations derived when V(max) is set to zero can be used to predict the minimum concentration requirement for a viable biofiltration process. The simulation results show that the model of De Visscher and Van Cleemput, modified to incorporate Haldane kinetics, provides a good description of the biofiltration performance for toluene removal biofilters. Predictions of the minimum concentration that can be treated indicate that conventional biofilters are not suitable for indoor air pollutant removal. PMID:18672719

Li, Gui Qin; De Visscher, Alex

2008-07-01

61

Soot formation in shock-tube pyrolysis of toluene, toluene-methanol, toluene-ethanol, and toluene-oxygen mixtures  

Microsoft Academic Search

Soot formation during the pyrolysis of argon diluted mixtures of toluene and binary mixtures of toluene-methanol and toluene-ethanol, and during the oxidation of toluene has been studied in a reflected shock tube. Soot induction times and rates of soot formation were measured at 632.8 and 1152.0 nm by a laser beam attenuation method and these showed an Arrhenius dependence on

A. Alexiou; A. Williams

1996-01-01

62

Tetrachloroethylene Exposure and Bladder Cancer Risk: A Meta-Analysis of Dry-Cleaning-Worker Studies  

PubMed Central

Background: In 2012, the International Agency for Research on Cancer classified tetrachloroethylene, used in the production of chemicals and the primary solvent used in dry cleaning, as “probably carcinogenic to humans” based on limited evidence of an increased risk of bladder cancer in dry cleaners. Objectives: We assessed the epidemiological evidence for the association between tetrachloroethylene exposure and bladder cancer from published studies estimating occupational exposure to tetrachloroethylene or in workers in the dry-cleaning industry. Methods: Random-effects meta-analyses were carried out separately for occupational exposure to tetrachloroethylene and employment as a dry cleaner. We qualitatively summarized exposure–response data because of the limited number of studies available. Results: The meta-relative risk (mRR) among tetrachloroethylene-exposed workers was 1.08 (95% CI: 0.82, 1.42; three studies; 463 exposed cases). For employment as a dry cleaner, the overall mRR was 1.47 (95% CI: 1.16, 1.85; seven studies; 139 exposed cases), and for smoking-adjusted studies, the mRR was 1.50 (95% CI: 0.80, 2.84; 4 case–control studies). Conclusions: Our meta-analysis demonstrates an increased risk of bladder cancer in dry cleaners, reported in both cohort and case–control studies, and some evidence for an exposure–response relationship. Although dry cleaners incur mixed exposures, tetrachloroethylene could be responsible for the excess risk of bladder cancer because it is the primary solvent used and it is the only chemical commonly used by dry cleaners that is currently identified as a potential bladder carcinogen. Relatively crude approaches in exposure assessment in the studies of “tetrachloroethylene-exposed workers” may have attenuated the relative risks. Citation: Vlaanderen J, Straif K, Ruder A, Blair A, Hansen J, Lynge E, Charbotel B, Loomis D, Kauppinen T, Kyyronen P, Pukkala E, Weiderpass E, Guha N. 2014. Tetrachloroethylene exposure and bladder cancer risk: a meta-analysis of dry-cleaning-worker studies. Environ Health Perspect 122:661–666;?http://dx.doi.org/10.1289/ehp.1307055

Vlaanderen, Jelle; Straif, Kurt; Ruder, Avima; Blair, Aaron; Hansen, Johnni; Lynge, Elsebeth; Charbotel, Barbara; Loomis, Dana; Kauppinen, Timo; Kyyronen, Pentti; Pukkala, Eero; Weiderpass, Elisabete

2014-01-01

63

Physiological pharmacokinetic modeling of inhalation exposure of tetrachloroethylene in rats and humans  

SciTech Connect

A physiologically-based pharmacokinetic model which incorporates biophysical parameters such as breathing and blood flow rates, blood and tissue volumes, and chemical partition coefficients is described. The model is used to predict chemical transport and metabolism in rats and humans for tetrachloroethylene, a chemical used extensively as a dry cleaning solvent. The concept of using body weight scaling of the physiological parameters is used to extrapolate results for exhaled air from rats to humans. Model results for inhalation of tetrachloroethylene are compared to empirical data for both species. 12 refs., 3 figs., 4 tabs.

Hetrick, D.M.; Ward, R.C.; Travis, C.C.

1986-01-01

64

Tetrachloroethylene exposure and bladder cancer risk: a meta-analysis of dry-cleaning-worker studies.  

PubMed

Background: In 2012, the International Agency for Research on Cancer classified tetrachloroethylene, used in the production of chemicals and the primary solvent used in dry cleaning, as "probably carcinogenic to humans" based on limited evidence of an increased risk of bladder cancer in dry cleaners.Objectives: We assessed the epidemiological evidence for the association between tetrachloroethylene exposure and bladder cancer from published studies estimating occupational exposure to tetrachloroethylene or in workers in the dry-cleaning industry.Methods: Random-effects meta-analyses were carried out separately for occupational exposure to tetrachloroethylene and employment as a dry cleaner. We qualitatively summarized exposure-response data because of the limited number of studies available.Results: The meta-relative risk (mRR) among tetrachloroethylene-exposed workers was 1.08 (95% CI: 0.82, 1.42; three studies; 463 exposed cases). For employment as a dry cleaner, the overall mRR was 1.47 (95% CI: 1.16, 1.85; seven studies; 139 exposed cases), and for smoking-adjusted studies, the mRR was 1.50 (95% CI: 0.80, 2.84; 4 case-control studies).Conclusions: Our meta-analysis demonstrates an increased risk of bladder cancer in dry cleaners, reported in both cohort and case-control studies, and some evidence for an exposure-response relationship. Although dry cleaners incur mixed exposures, tetrachloroethylene could be responsible for the excess risk of bladder cancer because it is the primary solvent used and it is the only chemical commonly used by dry cleaners that is currently identified as a potential bladder carcinogen. Relatively crude approaches in exposure assessment in the studies of "tetrachloroethylene-exposed workers" may have attenuated the relative risks.Citation: Vlaanderen J, Straif K, Ruder A, Blair A, Hansen J, Lynge E, Charbotel B, Loomis D, Kauppinen T, Kyyronen P, Pukkala E, Weiderpass E, Guha N. 2014. Tetrachloroethylene exposure and bladder cancer risk: a meta-analysis of dry-cleaning-worker studies. Environ Health Perspect 122:661-666;?http://dx.doi.org/10.1289/ehp.1307055. PMID:24659585

Vlaanderen, Jelle; Straif, Kurt; Ruder, Avima; Blair, Aaron; Hansen, Johnni; Lynge, Elsebeth; Charbotel, Barbara; Loomis, Dana; Kauppinen, Timo; Kyyronen, Pentti; Pukkala, Eero; Weiderpass, Elisabete; Guha, Neela

2014-07-01

65

Solubilization of trichloroethylene by polyelectrolyte/surfactant complexes  

SciTech Connect

An automated vapor pressure method is used to obtain solubilization isotherms for trichloroethylene (TCE) in polyelectrolyte/surfactant complexes throughout a wide range of solute activities at 20 and 25 C. The polyelectrolyte chosen is sodium poly(styrenesulfonate), PSS< and the surfactant is cetylpyridinium chloride or N-hexadecylpyridinium chloride, CPC. Data are fitted to the quadratic equation K = K[sub 0](1[minus][alpha]X + [beta]X[sup 2]), which correlates the solubilization equilibrium constant (K) with the mole fraction of TCE (X) in the micelles or complexes at each temperature. Activity coefficients are also obtained for TCE in the PSS/CPC complexes as a function of X. The general solubilization of TCE in PSS/CPC complexes resembles that of TCE in CPC micelles, as well as that of benzene or toluene in CPC micelles, suggesting that TCE solubilizes in ionic micelles both within the hydrocarbon micellar interior and near the micellar surface. The presence of the polyelectrolyte causes a small decrease in the ability of the cationic surfactant to solubilize TCE, while greatly reducing the concentration of the surfactant present in monomeric form. PSS/CPC complexes may be useful in colloid-enhanced ultrafiltration processes to purify organic-contaminated water.

Uchiyama, Hirotaka; Christian, S.D.; Tucker, E.E.; Scamehorn, J.F. (Univ. of Oklahoma, Norman, OK (United States))

1994-12-01

66

Apartment Residents' and Day Care Workers' Exposures to Tetrachloroethylene and Deficits in Visual Contrast Sensitivity  

Microsoft Academic Search

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

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

67

Dissolution of residual tetrachloroethylene in fractional wettability porous media: correlation development and application  

Microsoft Academic Search

This work explores the dissolution behavior of residual tetrachloroethylene (PCE) in chemically heterogeneous soils. A numerical solute transport simulator, that incorporates rate-limited dissolution and desorption using linear driving force expressions, was developed and applied to analyze soil column dissolution data and to conduct numerical dissolution experiments. Published mass transfer coefficients were unable to accurately predict the observed dissolution of entrapped

Scott A. Bradford; Thomas J. Phelan; Linda M. Abriola

2000-01-01

68

Anaerobic granule formation and tetrachloroethylene (TCE) removal in an upflow anaerobic sludge blanket (UASB) reactor  

Microsoft Academic Search

The granulation process was examined using synthetic wastewater containing tetrachloroethylene (TCE) in a 2 liters laboratory upflow anaerobic sludge blanket (UASB) reactor. The anaerobic biotransformation of TCE was investigated during the granulation process by reducing the HRT and increasing the chemical oxygen demand (COD) and TCE loadings. Anaerobic unacclimated sludge and glucose were used as seed and primary substrate, respectively.

Delia Teresa Sponza

2001-01-01

69

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...

70

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...

71

ACUTE AND CHRONIC TOXICITY OF SOME CHLORINATED BENZENES, CHLORINATED ETHANES, AND TETRACHLOROETHYLENE TO 'DAPHNIA MAGNA'  

EPA Science Inventory

Chronic effect and no effect concentrations (28 day) and acute toxicity (48 hr, LC50 and EC50) values were determined for Daphnia magna with some chlorinated benzenes, chlorinated ethanes, and tetrachloroethylene. Acute and chronic toxicity generally increased with the degree of ...

72

Biological exposure assessment to tetrachloroethylene for workers in the dry cleaning industry  

Microsoft Academic Search

BACKGROUND: The purpose of this study was to assess the feasibility of conducting biological tetrachloroethylene (perchloroethylene, PCE) exposure assessments of dry cleaning employees in conjunction with evaluation of possible PCE health effects. METHODS: Eighteen women from four dry cleaning facilities in southwestern Ohio were monitored in a pilot study of workers with PCE exposure. Personal breathing zone samples were collected

Lauralynn T McKernan; Avima M Ruder; Martin R Petersen; Misty J Hein; Christy L Forrester; Wayne T Sanderson; David L Ashley; Mary A Butler

2008-01-01

73

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

74

Test Pile Reactivity Loss Due to Trichloroethylene  

SciTech Connect

The presence of trichloroethylene in the test pile caused a continual decrease in pile reactivity. A system which removed, purified, and returned 12,000 cfh helium to the pile has held contamination to a negligible level and has permitted normal pile operation.

Plumlee, K.E.

2001-03-09

75

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

76

Excretion of Trichloroethylene Metabolites in Human Urine  

Microsoft Academic Search

Five healthy subjects were exposed to known concentrations of trichloroethylene (T.R.I.) for five hours. The amount retained was calculated. The excretion of the metabolites monochloroacetic acid (M.C.A.), trichloroacetic acid (T.C.A.), and trichloroethanol (T.C.E.) in the urine was measured over the next seven to 14 days. Metabolites excreted represented an average of 73% of the dose of T.R.I. retained (M.C.A. 4%,

B. Sou?ek; D. Vlachová

1960-01-01

77

Impacts of microbial community composition on isotope fractionation during reductive dechlorination of tetrachloroethylene  

Microsoft Academic Search

Isotope fractionation has been used with increasing frequency as a tool to quantify degradation of chlorinated aliphatic\\u000a pollutants in the environment. The objective of this research was to determine if the electron donor present in enrichment\\u000a cultures prepared from uncontaminated sediments influenced the extent of isotope fractionation of tetrachloroethylene (PCE),\\u000a either directly, or through its influence on microbial community composition.

Yiran Dong; Elizabeth C. Butler; R. Paul Philp; Lee R. Krumholz

2011-01-01

78

Rapid granulation and sludge retention for tetrachloroethylene removal in an upflow anaerobic sludge blanket reactor  

Microsoft Academic Search

A laboratory scale upflow anaerobic sludge blanket (UASB) reactor was operated at 35 °C for over 200 days to investigate the granulation mechanism during tetrachloroethylene (TCE) biodegradation. Anaerobic, unacclimated sludge and glucose were used as seed and primary substrate, respectively. TCE-degrading granules developed after 1.5 months of start-up. They grew at an accelerated pace for 7 months. The TCE-degrading granules

Delia Teresa Sponza

2001-01-01

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

Mineralization of trichloroethylene by heterotrophic enrichment cultures  

SciTech Connect

Microbial consortia capable of aerobically degrading greater than 99% of 50 mg/l exogenous trichloroethylene (TCE) have been enriched from TCE contaminated subsurface sediments. Concentrations of TCE greater than 300 mg/l were not degraded nor was TCE used as a sole energy source. Successful electron donors for growth included tryptone-yeast extract, methanol, methane or propane. The optimum temperature for growth was 22--37 C and the ph optimum was 7.0--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.

Phelps, T.J.; Ringelberg, D.; Mikell, A.T.; White, D.C. [Univ. of Tennessee, Knoxville, TN (United States). Inst. for Applied Microbiology]|[Oak Ridge National Lab., Knoxville, TN (United States); Fliermans, C.B. [E.I. DuPont de Nemours and Co., Aiken, SC (United States). Savannah River Lab.

1988-12-31

81

The treatment of Fasciolopsis buski infection in children: a comparison of thiabendazole, mebendazole, levamisole, pyrantel pamoate, hexylresorcinol and tetrachloroethylene.  

PubMed

Four relatively new broad spectrum anthelmintics (thiabendazole, mebendazole, levamisole and pyrantel pamoate) were compared with two older anthelmintics, (tetrachloroethylene and hexylresorcinol) to treat heavy Fasciolopis buski infections in 17 children aged 4-13 years in hospital. Tetrachloroethylene was the most effective drug in these 17 children and another 49. Large numbers of worms were expelled and faecal egg counts were markedly reduced (99%). The mean number of worms per child was 122 with a range of 7 to 818. All the other anthelmintics tested were ineffective; no worms or only a few were expelled after treatment. However, the oral administration of tetrachloroethylene and hexylresorcinol were associated with severe anaphylactic reactions which were prevented by prior treatment with antihistamines. PMID:4082261

Rabbani, G H; Gilman, R H; Kabir, I; Mondel, G

1985-01-01

82

C60 1,1,2,2-tetra-chloro-ethyl-ene tetra-solvate  

PubMed Central

In the title complex, C60·4C2Cl4, the C60 mol­ecule is located on an inversion centre and there are two tetra­chloro­ethyl­ene (TCE) mol­ecules in the asymmetric unit. Both TCE mol­ecules show positional disorder, with occupancy ratios of 0.75:0.25 and 0.56:0.44. Four fullerene C atoms form short contacts [3.208?(17) and 3.223?(17)?Å] with the centres of the TCE double bonds, indicating that C60–solvent inter­actions are largely ?–? in nature.

Arunkumar, C.; Bhyrappa, P.; Varghese, B.

2008-01-01

83

TETRACHLOROETHYLENE EXPOSURE AND RISK OF SCHIZOPHRENIA: OFFSPRING OF DRY CLEANERS IN A POPULATION BIRTH COHORT, PRELIMINARY FINDINGS  

PubMed Central

Tetrachloroethylene is a solvent used in dry cleaning with reported neurotoxic effects. Using proportional hazard methods, we examined the relationship between parental occupation as a dry cleaner and risk for schizophrenia in a prospective population-based cohort of 88, 829 offspring born in Jerusalem from 1964 through 1976, followed from birth to age 21–33 years. Of 144 offspring whose parents were dry cleaners, 4 developed schizophrenia. We observed an increased incidence of schizophrenia in offspring of parents who were dry cleaners (RR = 3.4, 95% CI, 1.3–9.2, p=0.01). Tetrachloroethylene exposure warrants further investigation as a risk factor for schizophrenia.

Perrin, Mary C.; Opler, Mark G.; Harlap, Susan; Harkavy-Friedman, Jill; Kleinhaus, Karine; Nahon, Daniella; Fennig, Shmuel; Susser, Ezra S.; Malaspina, Dolores

2009-01-01

84

Criteria for a Recommended Standard. Occupational Exposure to Trichloroethylene.  

National Technical Information Service (NTIS)

The report presents the criteria and the recommended standard based thereon which were prepared to meet the need for preventing occupational diseases arising from exposure to trichloroethylene. The proposed standard applies only to the processing, manufac...

1973-01-01

85

Simulation Studies Examining Possible Mechanisms of Trichloroethylene Carcinogenicity.  

National Technical Information Service (NTIS)

There has been much recent interest regarding methods of evaluating potential human cancer risks associated with trichloroethylene (TCE). Stochastic biologically based dose-response (BBDR) models offer possible means of quantifying these risks. BBDR model...

R. C. Lee G. E. Luebeck S. M. Bartell W. Griffith E. M. Faustman

1998-01-01

86

Bacterial Treatment System for the Remediation of Trichloroethylene.  

National Technical Information Service (NTIS)

14. Abstract A genetically altered bacterium Burkholderia (Pseudomonas) cepacia PR123 and closely related genetic derivatives were tested for bioreactor and in situ trichloroethylene (TOE) degradation. PRi 23 was shown to degrade TOE in a plugged flow bio...

M. S. Shields

1996-01-01

87

IRIS Toxicological Review of Trichloroethylene (Interagency Science Discussion Draft)  

EPA Science Inventory

EPA is releasing the draft report, Toxicological Review of Trichloroethylene, that was distributed to Federal agencies and White House Offices for comment during the Science Discussion step of the IRIS Assessment Development Process. Comments received from other Federal agencies ...

88

Gaseous Behavior of TCE (Trichloroethylene) Overlying a Contaminated Aquifer.  

National Technical Information Service (NTIS)

Shallow soil gas (<2 meters deep) was collected and analyzed for trichloroethylene (TCE) to determine the relationship with ground-water contamination directly below. The gaseous TCE plume was mapped with 46 probes and spanned three orders of magnitude in...

D. L. Marrin G. M. Thompson

1987-01-01

89

Biodegradation of trichloroethylene in a rotating biological contactor  

Microsoft Academic Search

A laboratory scale study was carried out to treat synthetic wastewater containing 30 mg\\/l of trichloroethylene in a rotating biological contactor (RBC). A mixed culture of bacteria consisting of nitrifiers, heterotrophs and Thiosphaera pantotropha could be developed and acclimated to achieve 99.89% removal of trichloroethylene (TCE) from synthetic wastewater at TCE loading of 0.0039 m3\\/m2 d and HRT of 3.5 days. A

Satinder K Brar; S. K Gupta

2000-01-01

90

Genotoxicity of trichloroethylene in the natural milieu.  

PubMed

Trichloroethylene (TCE) is a suspected genotoxic and carcinogenic compound which is usually present in the air, soil and water as pollutant. To estimate the genotoxic potential of TCE in a pure chemical form as well as an ingredient of the complex sample, Ames fluctuation test using TA98 and TA100 strains and Allium cepa genotoxicity assay were performed. For the genotoxicity analysis of TCE in natural milieu, the above mentioned tests were performed on the waste waters collected from two different stations of northern India namely Saharanpur and Aligarh, U.P., and these waste waters were supplemented with 50 and 100 mg/l of trichloroethylene. TCE alone was found to be non-genotoxic by both the testing system up to the range of 1000 mg/l concentration (data not shown). However, the test water samples supplemented with 100 mg/l of TCE, exhibited a significant increase in the genotoxicity compared with control by both the testing systems. In Ames fluctuation test, Mi(f) value was found to be increased by 41% and 53% with 100 mg/l of TCE supplemented Saharanpur and Aligarh waste water samples respectively, in the presence of S9 fraction compared with their respective controls. Allium cepa genotoxicity test also showed around 25% increase in total chromosomal aberration frequency following 100 mg/l TCE supplementation. However, supplementation of 50 mg/l TCE to the test water samples could not enhance the genotoxicity to a significant extent. From these results, we can conclude that TCE itself was non-genotoxic but it may promote mutation and/or DNA damage at a concentration of 100 mg/l under certain environmental conditions. We suggest that some chemicals in the test water samples might be interacting with TCE and/or metabolite(s) to cause the enhancement in genotoxicity. The mechanism of these synergistic effects should be explored further. PMID:21920816

Tabrez, Shams; Ahmad, Masood

2012-04-01

91

Neurobehavioral Effects of Toluene: A Review.  

National Technical Information Service (NTIS)

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 n...

V. A. Benignus

1981-01-01

92

Leaching of toluene-neoprene adhesive wastes.  

PubMed

This work consists of the study of the extraction of solvent (toluene) from a polymeric (neoprene) substrate during a leaching process. Total organic carbon (TOC) is the main contaminant parameter in the leaching of these systems due to the solution of the toluene and the dispersion of the polymer. The toxicity of the extracts was measured with a Microtox equipment, using Photobacteria phosphoreum, deducing that the toxicity of the extracts is low due to the low solubility of toluene but that the toxicity of toluene is high. On the basis of the experimental results, the amount of toluene diffused vs time in plane sheet systems was studied. A kinetic model has been developed considering two stages: In the first stage, the toluene diffuses into the system across the neoprene chains at a constant rate, not depending on the initial toluene concentration. This fact is explained by considering that there is a constant difference of the toluene concentration between the interface with the water and the inner part of the sample. In the second stage, the dispersion of the polymer with the corresponding amount of toluene takes place. The diffusion of toluene in the leaching process is compared and analyzed considering the diffusion of toluene in a desorption process in air so that the difference of toluene concentration between the interface and the interior can be estimated. A mathematical model is also proposed for considering the leaching process in other operating conditions. PMID:11351545

Font, R; Sabater, M C; Martínez, M A

2001-03-01

93

27 CFR 21.132 - Toluene.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Toluene. 21.132 Section 21.132 Alcohol...Specifications for Denaturants § 21.132 Toluene. (a) Distillation range. ...Standard No. D 362-75 for industrial grade toluene; for incorporation by reference,...

2009-04-01

94

27 CFR 21.132 - Toluene.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Toluene. 21.132 Section 21.132 Alcohol...Specifications for Denaturants § 21.132 Toluene. (a) Distillation range. ...Standard No. D 362-75 for industrial grade toluene; for incorporation by reference,...

2010-04-01

95

Risk of learning and behavioral disorders following prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water  

Microsoft Academic Search

This population-based retrospective cohort study examined the association between developmental disorders of learning, attention and behavior and prenatal and early postnatal drinking water exposure to tetrachloroethylene (PCE) on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling

Patricia A. Janulewicz; Roberta F. White; Michael R. Winter; Janice M. Weinberg; Lisa E. Gallagher; Veronica Vieira; Thomas F. Webster; Ann Aschengrau

2008-01-01

96

SURFACTANT ENHANCED RECOVERY OF TETRACHLOROETHYLENE FROM A POROUS MEDIUM CONTAINING LOW PERMEABILITY LENSES. 1. EXPERIMENTAL STUDIES. (R825409)  

EPA Science Inventory

Abstract A matrix of batch, column and two-dimensional (2-D) box experiments was conducted to investigate the coupled effects of rate-limited solubilization and layering on the entrapment and subsequent recovery of a representative dense NAPL, tetrachloroethylene (PCE)...

97

Enhancement of granule formation and sludge retainment for tetrachloroethylene (TCE) removal in an upflow anaerobic sludge blanket (UASB) reactor  

Microsoft Academic Search

Tetrachloroethylene (TCE) in wastewater was effectively removed at 35 °C over 200 days in an upflow anaerobic sludge blanket (UASB) reactor in order to investigate the formation of TCE degrading granules. Anaerobic unacclimated sludge and glucose were used as seed and primary substrate, respectively. TCE degrading massive initial granules were developed after 1.5 months of start-up, which grew at an

Delia Teresa Sponza

2003-01-01

98

Toluene stability Space Station Rankine power system  

NASA Technical Reports Server (NTRS)

A dynamic test loop is designed to evaluate the thermal stability of an organic Rankine cycle working fluid, toluene, for potential application to the Space Station power conversion unit. Samples of the noncondensible gases and the liquid toluene were taken periodically during the 3410 hour test at 750 F peak temperature. The results obtained from the toluene stability loop verify that toluene degradation will not lead to a loss of performance over the 30-year Space Station mission life requirement. The identity of the degradation products and the low rates of formation were as expected from toluene capsule test data.

Havens, V. N.; Ragaller, D. R.; Sibert, L.; Miller, D.

1987-01-01

99

Uncertainties in health-risk assessment: an integrated case study based on tetrachloroethylene in California groundwater  

SciTech Connect

Population risk to an environmental contaminant is represented as the product of a source term; the exposure function, which converts the source into a lifetime-equivalent contact rate in the population; the fraction metabolized; the toxic potency associated with the delivered dose; and the size of the exposed population. Using case studies for contamination of groundwater in California with tetrachloroethylene (PCE), the combined uncertainty in exposure and dose-response models is characterized. Three key issues are addressed: (a) uncertainty in quantifying pathway exposure factors that relate measured environmental concentrations to levels of contact in the exposed population; (b) the uncertainty in the human dose-response models derived from animal data; and (c) an overview of important contributors to the overall uncertainty in population risk estimates.

McKone, T.E.; Bogen, K.T. (Lawrence Livermore National Laboratory, University of California, Livermore (United States))

1992-02-01

100

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

PubMed Central

There is little information on the impact of solvent-contaminated drinking water on pregnancy outcomes. This retrospective cohort study examined whether maternal exposure to tetrachloroethylene (PCE) - contaminated drinking water in the Cape Cod region 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 histories, and confounding variables. Exposure was estimated using water distribution system modeling software. No meaningful associations were seen between PCE exposure level and the risk of clinically recognized pregnancy loss at the exposure levels experienced by the study population. Because PCE remains a common water contaminant, it is important to continue monitoring its impact on women and their pregnancies.

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

2010-01-01

101

Behaviour of rats exposed to trichloroethylene vapour.  

PubMed Central

Rats were exposed to trichloroethylene (TCE) vapour for about five five-day weeks at concentrations from 100 to 1 000 ppm, and at 100 ppm for 12 1/2 weeks. The social behaviour of paired male rats was observed periodically in the home cage for five minutes after they had been exposed to TCE. The principal finding was a consistent reduction of up to 24% in the total acitivity. A single day's exposure to TCE was sufficient at the highest concentration. At 100 ppm, a similar decline in activity was significant after 1 1/2 weeks' exposure in one experiment and 8 1/2 weeks' in another. The decline in activity was fairly uniform and not usually because of specific reductions in particular kinds of behaviour. However, exploration of the cage and submission to, or escape from, the other rat were sometimes specifically reduced. In an 'exploration-thirst' test, rats were deprived of water overnight and placed on two or three occasions in a previously unfamiliar cage. Rats exposed to 100, 200, or 1 000 ppm TCE found water and began drinking sooner than their controls without altering the rate of movement about the cage. These results suggest lowered performance in a familiar situation where rats are usually very active and some loss of inhibitory control in an unfamiliar one. At the present threshold limit value, repeated exposure to TCE eventually had effects similar to those of one day's exposure to a higher concentration, but only after a widely variable delay.

Silverman, A P; Williams, H

1975-01-01

102

Current trends in trichloroethylene biodegradation: a review.  

PubMed

Over the past few years biodegradation of trichloroethylene (TCE) using different microorganisms has been investigated by several researchers. In this review article, an attempt has been made to present a critical summary of the recent results related to two major processes--reductive dechlorination and aerobic co-metabolism used for TCE biodegradation. It has been shown that mainly Clostridium sp. DC-1, KYT-1, Dehalobacter, Dehalococcoides, Desulfuromonas, Desulfitobacterium, Propionibacterium sp. HK-1, and Sulfurospirillum bacterial communities are responsible for the reductive dechlorination of TCE. Efficacy of bacterial communities like Nitrosomonas, Pseudomonas, Rhodococcus, and Xanthobacter sp. etc. for TCE biodegradation under aerobic conditions has also been examined. Mixed cultures of diazotrophs and methanotrophs have been used for TCE degradation in batch and continuous cultures (biofilter) under aerobic conditions. In addition, some fungi (Trametes versicolor, Phanerochaete chrysosporium ME-446) and Actinomycetes have also been used for aerobic biodegradation of TCE. The available information on kinetics of biofiltration of TCE and its degradation end-products such as CO2 are discussed along with the available results on the diversity of bacterial community obtained using molecular biological approaches. It has emerged that there is a need to use metabolic engineering and molecular biological tools more intensively to improve the robustness of TCE degrading microbial species and assess their diversity. PMID:23057686

Shukla, Awadhesh Kumar; Upadhyay, Siddh Nath; Dubey, Suresh Kumar

2014-06-01

103

Biodegradation of trichloroethylene by Methylosinus trichosporium OB3b.  

PubMed Central

The methanotroph Methylosinus trichosporium OB3b, a type II methanotroph, degraded trichloroethylene at rates exceeding 1.2 mmol/h per g (dry weight) following the appearance of soluble methane monooxygenase in continuous and batch cultures. Cells capable oxidizing trichloroethylene contained components of soluble methane monooxygenase as demonstrated by Western blot (immunoblot) analysis with antibodies prepared against the purified enzyme. Growth of cultures in a medium containing 0.25 microM or less copper sulfate caused derepression of the synthesis of soluble methane monooxygenase. In these cultures, the specific rates of methane and methanol oxidation did not change during growth, while trichloroethylene oxidation increased with the appearance of soluble methane monooxygenase. M. trichosporium OB3b cells that contained soluble methane monooxygenase also degraded vinyl chloride, 1,1-dichloroethylene, cis-1,2-dichloroethylene, and trans-1,2-dichloroethylene. Images

Tsien, H C; Brusseau, G A; Hanson, R S; Waclett, L P

1989-01-01

104

Electrochemical fluorination of trichloroethylene and N, N-dimethyltrifluoroacetamide  

NASA Technical Reports Server (NTRS)

Fluorination of trichloroethylene and N, N-dimethyltrifluoroacetamide was carried out on a laboratory scale in an advanced Simons type electrochemical apparatus which could be operated automatically from ambient to 50 psi pressure. A variety of fluorine-substituted products are formed, depending upon electrolysis conditions and concentrations of reactant relative to the NaF, KF, HF electrolyte. A new reaction mechanism of electrochemical fluorination of trichloroethylene is proposed. The solvency-to-fluorine content relationship of fluorinated N, N-dimethyltrifluoroacetamide is described.

Hsu, L. C.

1979-01-01

105

Displacement of soil pore water by trichloroethylene  

SciTech Connect

Dense nonaqueous phase liquids (DNAPLS) are important pollutants because of their widespread use as chemical and industrial solvents. An example of the pollution caused by the discharge of DNAPLs is found at the Picatinny Arsenal, New Jersey, where trichloroethylene (TCE) has been discharged directly into the unsaturated zone. This discharge has resulted in the formation of a plume of TCE-contaminated water in the aquifer downgradient of the discharge. A zone of dark-colored groundwater containing a high dissolved organic C content has been found near the point of discharge of the TCE. The colored-water plume extends from the point of discharge at least 30 m (100 feet) downgradient. Fulvic acids isolated from the colored-waters plume, from water from a background well that has not been affected by the discharge of chlorinated solvents, and from soil pore water collected in a lysimeter installed at an uncontaminated site upgradient of the study area have been compared. Nuclear magnetic resonance spectra of the fulvic acids from the colored waters and from the lysimeter am very similar, but are markedly different from the nuclear magnetic resonance spectrum of the fulvic acid from the background well. The three-dimensional fluorescence spectrum and the DOC fractionation profile of the colored groundwater and the soil pore water are very similar to each other, but quite different from those of the background water. It is proposed from these observations that this colored water is soil pore water that has been displaced by a separate DNAPL liquid phase downward to the saturated zone. 15 refs., 6 figs., 4 tabs.

Wershaw, R.L.; Aiken, G.R. [Denver Federal Center, CO (United States); Imbrigiotta, T.E. [Geological Survey, West Trenton, NJ (United States)

1994-07-01

106

Tetrachloroethylene in Drinking Water and Birth Outcomes at the US Marine Corps Base at Camp Lejeune, North Carolina  

Microsoft Academic Search

A study of mean birth weight, small-for-gestational-age infants, and preterm birth was conducted at the US Marine Corps Base at Camp Lejeune, North Carolina, where drinking water was contaminated with volatile organic compounds. Tetrachloroethylene (PCE) was the predominant contaminant. The authors used multiple linear and logistic regression to analyze 1968-1985 data from 11,798 birth certificates. Overall, at most weak associations

N. Sonnenfeld; I. Hertz-Picciotto; W. E. Kaye

2001-01-01

107

Tetrachloroethylene as new film-forming additive to propylene carbonate-based electrolytes for lithium ion batteries with graphitic anode  

Microsoft Academic Search

Tetrachloroethylene (TCE) has been investigated as a new film-forming additive to propylene carbonate (PC)-based electrolytes for use in lithium ion batteries. Even in small additive amounts (3 vol.%) TCE was capable of preventing PC co-intercalation into graphite. The formation of a stable passivating film on the graphite surface is believed to be the reason for the improved cell performance. It

Yongsheng Hu; Weihe Kong; Zhaoxiang Wang; Xuejie Huang; Liquan Chen

2005-01-01

108

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

109

Evoked trigeminal nerve potential in chronic trichloroethylene intoxication.  

PubMed

Results of a study of trigeminal nerve impairment resulting from trichloroethylene intoxication by the somatosensory-evoked potential method reveal three kinds of abnormalities: increased stimulation voltage, excessive latency delay with morphological abnormalities, and excessive graph amplitude. These abnormalities confirm clinical disturbance (hypesthesia of the trigeminal nerve area) and open debate about the real mechanism of trichloroethylene neurotoxicity. Industrial intoxication by solvents, particularly trichloroethylene, is common. We have conducted a study of 188 workers chronically exposed to trichloroethylene and have confirmed the selective neurological disturbances of this intoxication in the trigeminal nerve (20%) [3, 10]. We utilized a new experimental method, developed for studies of chronic intoxications effecting the median nerve [5, 8], of recording the somatosensory evoked potential following stimulation of the trigeminal nerve [4, 6, 7]. The workers in this study were selected following clinical evaluation of their facial sensitivity and trigeminal nerve reflexes. In this paper we present our preliminary results on 11 workers, 9 suffering effects of intoxication and 2 controls. PMID:7143527

Barret, L; Arsac, P; Vincent, M; Faure, J; Garrel, S; Reymond, F

1982-06-01

110

Health risk assessment of environmental exposure to trichloroethylene  

Microsoft Academic Search

A review of the animal data showed trichloroethylene (TRI) to be of low acute toxicity. Repeated exposure showed that the target organs were the liver, and to a lesser extent, the kidney. TRI is not mutagenic or only marginally mutagenic. There is no evidence of fetotoxicity or teratogenicity. TRI is judged not to exhibit chronic neurotoxicity. Lifetime bioassays resulted in

L. P. Brown; D. G. Farrar; C. G. de Rooij

1990-01-01

111

EFFECTS OF THERMAL TREATMENTS ON THE CHEMICAL REACTIVITY OF TRICHLOROETHYLENE  

EPA Science Inventory

A series of experiments was completed to investigate abiotic degradation and reaction product formation of trichloroethylene (TCE) when heated. A quartz-tube apparatus was used to study short residence time and high temperature conditions that are thought to occur during thermal ...

112

ADSORPTION AND CATALYTIC DESTRUCTION OF TRICHLOROETHYLENE IN HYDROPHOBIC ZEOLITES  

EPA Science Inventory

Several chromium exchanged ZSM-5 zeolites of varying SiO2/Al2O3 ratio were prepared and investigated for ambient (23 ?C) adsorption and subsequent oxidative destruction (250-400 ?C) of gaseous trichloroethylene (TCE, Cl2C=CHCl) in a humid air stream. With an increase in the SiO2...

113

IRIS Toxicological Review of Trichloroethylene (TCE) (External Review Draft)  

EPA Science Inventory

EPA is conducting a peer review and public comment of the scientific basis supporting the human health hazard and dose-response assessment of Trichloroethylene (TCE) that when finalized will appear on the Integrated Risk Information System (IRIS) database. Please refer to ...

114

THE EFFECT OF VOLTAGE ON ELECTROCHEMICAL DEGRADATION OF TRICHLOROETHYLENE  

EPA Science Inventory

This study investigates electrochemical degradation of Trichloroethylene (TCE) using granular graphite as electrodes in a flow-through reactor system. The experiments were conducted to obtain information on the effect of voltage and flow rates on the degradation rates of TCE. The...

115

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...

116

Carcinogenesis Bioassay of Trichloroethylene. CAS No. 79-01-6.  

National Technical Information Service (NTIS)

Trichloroethylene (TCE) is a halogenated chemical used primarily as a solvent in industrial degreasing operations. Industrial grade TCE was bioassayed using both sexes of Osborne-Mendel rats and B6C3F1 mice. Two dose levels were administered. Animals were...

1976-01-01

117

Impact of Iron Sulfide Transformation on Trichloroethylene Degradation  

EPA Science Inventory

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 enginee...

118

IRIS Toxicological Review of Trichloroethylene (Interagency Science Consultation Draft)  

EPA Science Inventory

On November 3, 2009, the Toxicological Review of Trichloroethylene and the charge to external peer reviewers were released for external peer review and public comment. The Toxicological Review and charge were reviewed internally by EPA and by other federal agencies and White Hous...

119

Dermal Uptake of Dilute Aqueous Trichloroethylene by Hairless Guinea Pigs.  

National Technical Information Service (NTIS)

Percutaneous absorption was measured in sodium pentobarbital sedated female hairless guinea pigs dermally exposed for 70 min to (14) C labeled trichloroethylene (TCE) present at either low (20- to 110-ppb) or high (100,000-pbb) concentrations in water at ...

B. W. Colston K. T. Bogen L. K. Machicao

1990-01-01

120

Studies of TPB dissolved in Toluene  

Microsoft Academic Search

Scintillation light in liquid argon calorimeters is produced at 128 nm. This must be shifted to the visible so that the light can be observed by phototubes. A traditional method for accomplishing this is to dissolve Tetraphenyl butadiene and plastic into toluene, and then use this mixture to coat surfaces. After the toluene evaporates, the TPB in the thin plastic

Ruel Jerry; Lindley Winslow; Janet Conrad

2010-01-01

121

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

122

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

123

Integrating address geocoding, land use regression, and spatiotemporal geostatistical estimation for groundwater tetrachloroethylene.  

PubMed

Geographic information systems (GIS) based techniques are cost-effective and efficient methods used by state agencies and epidemiology researchers for estimating concentration and exposure. However, budget limitations have made statewide assessments of contamination difficult, especially in groundwater media. Many studies have implemented address geocoding, land use regression, and geostatistics independently, but this is the first to examine the benefits of integrating these GIS techniques to address the need of statewide exposure assessments. A novel framework for concentration exposure is introduced that integrates address geocoding, land use regression (LUR), below detect data modeling, and Bayesian Maximum Entropy (BME). A LUR model was developed for tetrachloroethylene that accounts for point sources and flow direction. We then integrate the LUR model into the BME method as a mean trend while also modeling below detects data as a truncated Gaussian probability distribution function. We increase available PCE data 4.7 times from previously available databases through multistage geocoding. The LUR model shows significant influence of dry cleaners at short ranges. The integration of the LUR model as mean trend in BME results in a 7.5% decrease in cross validation mean square error compared to BME with a constant mean trend. PMID:22264162

Messier, Kyle P; Akita, Yasuyuki; Serre, Marc L

2012-03-01

124

Surfactant enhanced recovery of tetrachloroethylene from a porous medium containing low permeability lenses. 1. Experimental studies  

NASA Astrophysics Data System (ADS)

A matrix of batch, column and two-dimensional (2-D) box experiments was conducted to investigate the coupled effects of rate-limited solubilization and layering on the entrapment and subsequent recovery of a representative dense NAPL, tetrachloroethylene (PCE), during surfactant flushing. Batch experiments were performed to determine the equilibrium solubilization capacity of the surfactant, polyoxyethylene (20) sorbitan monooleate (Tween 80), and to measure fluid viscosity, density and interfacial tension. Results of one-dimensional column studies indicated that micellar solubilization of residual PCE was rate-limited at Darcy velocities ranging from 0.8 to 8.2 cm/h and during periods of flow interruption. Effluent concentration data were used to develop effective mass transfer coefficient ( Ke) expressions that were dependent upon the Darcy velocity and duration of flow interruption. To simulate subsurface heterogeneity, 2-D boxes were packed with layers of F-70 Ottawa sand and Wurtsmith aquifer material within 20-30 mesh Ottawa sand. A 4% Tween 80 solution was then flushed through PCE-contaminated boxes at several flow velocities, with periods of flow interruption. Effluent concentration data and visual observations indicated that both rate-limited solubilization and pooling of PCE above the fine layers reduced PCE recovery to levels below those anticipated from batch and column measurements. These experimental results demonstrate the potential impact of both mass transfer limitations and subsurface layering on the recovery of PCE during surfactant enhanced aquifer remediation.

Taylor, Tammy P.; Pennell, Kurt D.; Abriola, Linda M.; Dane, Jacob H.

2001-04-01

125

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

2012-01-01

126

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

SciTech Connect

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, or other saturated organics. None of the cultures tested were able to degrade perchloroethylene (PCE) or carbon tetrachloride (CCl[sub 4]). For the four cultures tested, degradation of each of the chlorinated organics resulted in cell inactivation due to product toxicity. In all cases, the toxic products were rapidly depleted, leaving no toxic residues in solution. Among the four tested cultures, the resting cells of methane oxidizers exhibited the highest transformation capacities (T[sub c]) for TCE, CF, and 1,2-DCA. The T[sub c] for each chlorinated organic was observed to be inversely proportional to the chlorine carbon ratio (Cl/C). The addition of low concentrations of growth substrate or some catabolic intermediates enhanced TCE transformation capacities and degradation rates, presumably due to the regeneration of reducing energy (NADH); however, addition of higher concentrations of most amendments reduced TCE transformation capacities and degradation rates. Reducing energy limitations and amendment toxicity may significantly affect T[sub c] measurements, causing a masking of the toxicity associated with chlorinated organic degradation.

Chang, H.L.; Alvarez-Cohen, L. (Univ. of California, Berkeley, CA (United States). Dept. of Civil Engineering)

1995-03-05

127

Anticonvulsant and antipunishment effects of toluene  

SciTech Connect

Toluene can have striking acute behavioral effects and is subject to abuse by inhalation. To determine if its actions resemble those of drugs used in the treatment of anxiety (anxiolytics), two sets of experiments were undertaken. Inasmuch as prevention of pentylenetetrazol-induced convulsions is an identifying property of this class of agents, the authors first demonstrated that pretreatment of mice with injections of toluene delayed the onset of convulsive signs and prevented the tonic extension phase of the convulsant activity in a dose-related manner. Injections of another alkyl benzene, m-xylene, were of comparable potency to toluene. Inhalation of toluene delayed the time of death after pentylenetetrazol injection in a manner related to the duration and concentration of exposure; at lower convulsant doses, inhalation of moderate concentrations (EC/sub 58/, 1300 ppm) prevented death. Treatment with a benzodiazepine receptor antagonist (Ro 15-1788) failed to reduce the anticonvulsant activity of inhaled toluene. Anxiolytics also attenuate the reduction in response rate produced by punishment with electric shock. Toluene increased rates of responding suppressed by punishment when responding was maintained under a multiple fixed-interval fixed-interval punishment schedule of reinforcement. Distinct antipunishment effects were observed in rats after 2 hr of exposure to 1780 and 3000 ppm of toluene; the rate-increasing effects of toluene were related to concentration and to time after the termination of exposure. Thus, toluene and m-xylene resemble in several respects clinically useful drugs such as the benzodiazepines. 51 references, 3 figures, 2 tables.

Wood, R.W.; Coleman, J.B.; Schuler, R.; Cox, C.

1984-01-01

128

The pyrolysis of toluene and ethyl benzene  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

129

Cloning and characterization of a Pseudomonas mendocina KR1 gene cluster encoding toluene-4-monooxygenase.  

PubMed Central

Pseudomonas mendocina KR1 metabolizes toluene as a carbon source by a previously unknown pathway. The initial step of the pathway is hydroxylation of toluene to form p-cresol by a multicomponent toluene-4-monooxygenase (T4MO) system. The T4MO enzyme system has broad substrate specificity and provides a new opportunity for biodegradation of toxic compounds and bioconversions. Its known activities include conversion of a variety of phenyl compounds into the phenolic derivatives and the complete degradation of trichloroethylene. We have cloned and characterized a gene cluster from KR1 that determines the offO activity. To clone the T4MO genes, KR1 DNA libraries were constructed in Escherichia coli HB101 by using a broad-host-range vector and transferred to a KR1 mutant able to grow on p-cresol but not on toluene. An insert consisting of two SacI fragments of identical size (10.2 kb) was shown to complement the mutant for growth on toluene. One of the SacI fragments, when cloned into the E. coli vector pUC19, was found to direct the synthesis of indigo dye. The indigo-forming property was correlated with the presence of T4MO activity. The T4MO genes were mapped to a 3.6-kb region, and the direction of transcription was determined. DNA sequencing and N-terminal amino acid determination identified a five-gene cluster, tmoABCDE, within this region. Expression of this cluster carrying a single mutation in each gene demonstrated that each of the five genes is essential for T4MO activity. Other evidence presented indicated that none of the tmo genes was involved in the regulation of the tmo gene cluster, in the control of substrate transport for the T4MO system, or in major processing of the products of the tmo genes. It was tentatively concluded that the tmoABCDE genes encode structural polypeptides of the T4MO enzyme system. One of the tmo genes was tentatively identified as a ferredoxin gene. Images

Yen, K M; Karl, M R; Blatt, L M; Simon, M J; Winter, R B; Fausset, P R; Lu, H S; Harcourt, A A; Chen, K K

1991-01-01

130

Prenatal Exposure to Tetrachloroethylene-Contaminated Drinking Water and the Risk of Adverse Birth Outcomes  

PubMed Central

Background Prior studies of prenatal exposure to tetrachloroethylene (PCE) have shown mixed results regarding its effect on birth weight and gestational age. Objectives In this retrospective cohort study we examined whether PCE contamination of public drinking-water supplies in Massachusetts influenced the birth weight and gestational duration of children whose mothers were exposed before the child’s delivery. Methods The study included 1,353 children whose mothers were exposed to PCE-contaminated drinking water and a comparable group of 772 children of unexposed mothers. Birth records were used to identify subjects and provide information on the outcomes. Mothers completed a questionnaire to gather information on residential histories and confounding variables. PCE exposure was estimated using EPANET water distribution system modeling software that incorporated a fate and transport model. Results We found no meaningful associations between PCE exposure and birth weight or gestational duration. Compared with children whose mothers were unexposed during the year of the last menstrual period (LMP), adjusted mean differences in birth weight were 20.9, 6.2, 30.1, and 15.2 g for children whose mothers’ average monthly exposure during the LMP year ranged from the lowest to highest quartile. Similarly, compared with unexposed children, adjusted mean differences in gestational age were ?0.2, 0.1, ?0.1, and ?0.2 weeks for children whose mothers’ average monthly exposure ranged from the lowest to highest quartile. Similar results were observed for two other measures of prenatal exposure. Conclusions These results suggest that prenatal PCE exposure does not have an adverse effect on these birth outcomes at the exposure levels experienced by this population.

Aschengrau, Ann; Weinberg, Janice; Rogers, Sarah; Gallagher, Lisa; Winter, Michael; Vieira, Veronica; Webster, Thomas; Ozonoff, David

2008-01-01

131

Biological exposure assessment to tetrachloroethylene for workers in the dry cleaning industry  

PubMed Central

Background The purpose of this study was to assess the feasibility of conducting biological tetrachloroethylene (perchloroethylene, PCE) exposure assessments of dry cleaning employees in conjunction with evaluation of possible PCE health effects. Methods Eighteen women from four dry cleaning facilities in southwestern Ohio were monitored in a pilot study of workers with PCE exposure. Personal breathing zone samples were collected from each employee on two consecutive work days. Biological monitoring included a single measurement of PCE in blood and multiple measurements of pre- and post-shift PCE in exhaled breath and trichloroacetic acid (TCA) in urine. Results Post-shift PCE in exhaled breath gradually increased throughout the work week. Statistically significant correlations were observed among the exposure indices. Decreases in PCE in exhaled breath and TCA in urine were observed after two days without exposure to PCE. A mixed-effects model identified statistically significant associations between PCE in exhaled breath and airborne PCE time weighted average (TWA) after adjusting for a random participant effect and fixed effects of time and body mass index. Conclusion Although comprehensive, our sampling strategy was challenging to implement due to fluctuating work schedules and the number (pre- and post-shift on three consecutive days) and multiplicity (air, blood, exhaled breath, and urine) of samples collected. PCE in blood is the preferred biological index to monitor exposures, but may make recruitment difficult. PCE TWA sampling is an appropriate surrogate, although more field intensive. Repeated measures of exposure and mixed-effects modeling may be required for future studies due to high within-subject variability. Workers should be monitored over a long enough period of time to allow the use of a lag term.

McKernan, Lauralynn T; Ruder, Avima M; Petersen, Martin R; Hein, Misty J; Forrester, Christy L; Sanderson, Wayne T; Ashley, David L; Butler, Mary A

2008-01-01

132

Atmospheric oxidation mechanism of toluene.  

PubMed

The atmospheric oxidation mechanism of toluene initiated by OH radical addition is investigated by quantum chemistry calculations at M06-2X, G3MP2-RAD, and ROCBS-QB3 levels and by kinetics calculation by using transition state theory and unimolecular reaction theory coupled with master equation (RRKM-ME). The predicted branching ratios are 0.15, 0.59, 0.05, and 0.14 for OH additions to ipso, ortho, meta, and para positions (forming R1-R4 adducts), respectively. The fate of R2, R4, and R1 is investigated in detail. In the atmosphere, R2 reacts with O2 either by irreversible H-abstraction to form o-cresol (36%), or by reversible recombination to R2-1OO-syn and R2-3OO-syn, which subsequently cyclize to bicyclic radical R2-13OO-syn (64%). Similarly, R4 reacts with O2 with branching ratios of 61% for p-cresol and 39% for R4-35OO-syn, while reaction of R1 and O2 leads to R1-26OO-syn. RRKM-ME calculations show that the reactions of R2/R4 with O2 have reached their high-pressure limits at 760 Torr and the formation of R2-16O-3O-s is only important at low pressure, i.e., 5.4% at 100 Torr. The bicyclic radicals (R2-13OO-syn, R4-35OO-syn, and R1-26OO-syn) will recombine with O2 to produce bicyclic alkoxy radicals after reacting with NO. The bicyclic alkoxy radicals would break the ring to form products methylglyoxal/glyoxal (MGLY/GLY) and their corresponding coproducts butenedial/methyl-substituted butenedial as proposed in earlier studies. However, a new reaction pathway is found for the bicyclic alkoxy radicals, leading to products MGLY/GLY and 2,3-epoxybutandial/2-methyl-2,3-epoxybutandial. A new mechanism is proposed for the atmospheric oxidation mechanism of toluene based on current theoretical and previous theoretical and experimental results. The new mechanism predicts much lower yield of GLY and much higher yield of butenedial than other atmospheric models and recent experimental measurements. The new mechanism calls for detection of proposed products 2,3-epoxybutandial and 2-methyl-2,3-epoxybutandial. PMID:24901213

Wu, Runrun; Pan, Shanshan; Li, Yun; Wang, Liming

2014-06-26

133

Transport of Trichloroethylene (TCE) in Natural Soil by Electroosmosis  

Microsoft Academic Search

Contamination in low permeability soils poses a significant technical challenge to in situ remediation, primarily due to low\\u000a mobilization of the contaminants and difficulty in uniform delivery of treatment reagents. An alternative approach using electroosmosis\\u000a (EO) is used to mobilize Trichloroethylene (TCE) in soil. However, the EO approach causes significant chemical changes in\\u000a the soil which may affect transport and\\/or

Souhail R. Al-Abed; Jiann-Long Chen

134

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

135

Subsurface microbial communities and degradative capacities during trichloroethylene bioremediation  

SciTech Connect

Subsurface amendments of air, methane, and nutrients were investigated for the in situ stimulation of trichloroethylene- degrading microorganisms at the US DOE Savannah River Integrated Demonstration. Amendments were injected into a lower horizontal well coupled with vacuum extraction from the vadose zone horizontal well. The amendments were sequenced to give increasingly more aggressive treatments. Microbial populations and degradative capacities were monitored in groundwaters samples bimonthly.

Pfiffner, S.M.; Ringelberg, D.B.; Hedrick, D.B.; Phelps, T.J.; Palumbo, A.V.

1995-12-31

136

Oxidation mechanisms of toluene and benzene  

NASA Technical Reports Server (NTRS)

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

Bittker, David A.

1995-01-01

137

Primary atmospheric oxidation mechanism for toluene.  

PubMed

The products of the primary OH-initiated oxidation of toluene were investigated using the turbulent flow chemical ionization mass spectrometry technique at temperatures ranging from 228 to 298 K. A major dienedial-producing pathway was detected for the first time for toluene oxidation, and glyoxal and methylglyoxal were found to be minor primary oxidation products. The results suggest that secondary oxidation processes involving dienedial and epoxide primary products are likely responsible for previous observations of glyoxal and methylglyoxal products from toluene oxidation. Because the dienedial-producing pathway is a null cycle for tropospheric ozone production and glyoxal and methylglyoxal are important secondary organic aerosol precursors, these new findings have important implications for the modeling of toluene oxidation in the atmosphere. PMID:19118482

Baltaretu, Cristian O; Lichtman, Eben I; Hadler, Amelia B; Elrod, Matthew J

2009-01-01

138

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...

139

Health assessment for Nutmeg Valley, Wolcott, Connecticut, Region 1. CERCLIS No. CTSI88045. Preliminary report  

SciTech Connect

The Nutmeg Valley Industrial Park is listed on the National Priorities List. The site is an industrial park containing 40 companies (light industry metal working and finishing) and 20 private residences. The contaminants present in groundwater at the site are trichloroethylene, benzene, ethyl benzene, toluene, xylene, methylene chloride, trans 1,2-dichloroethane, 1,1,1-trichloroethane, tetrachloroethylene, pentane, carbon tetrachloride, and chloroform. Investigation into the extent of contamination in other pathways is ongoing.

Not Available

1988-05-02

140

Reduction of benzene toxicity by toluene  

SciTech Connect

BDF{sub 1} mice were exposed in inhalation chambers to benzene (900 ppm, 300 ppm) and/or toluene (500 ppm, 250 ppm) 6 hr per day, 5 days per week, for up to 8 weeks. Benzene alone induced a slight anemia after 4 and 8 weeks and a reduction of BFU-E and CFU-E numbers in the marrow. The coexposure to toluene reduced the degree of anemia. These results confirm previous studies where toluene was found to reduce benzene toxicity. This protective effect was most pronounced when DNA damage was studied in peripheral blood cells, bone marrow, and liver using the single cell gel (SCG) assay. With benzene alone, either with 300 or 900 ppm, a significant increase in DNA damage was detected in cells sampled from all three organs. Toluene alone did not induce a significant increase in DNA damage. The coexposure of benzene and toluene reduced the extent of DNA damage to about 50% of benzene alone. This result is considered a clear indication for a protective effect of toluene on the genetic toxicity of benzene. 18 refs., 7 figs., 3 tabs.

Plappert, U.; Barthel, E.; Seidel, H.J. [Universitaet Ulm (Germany)

1994-12-31

141

USE OF CARBON STABLE ISOTOPE TO INVESTIGATE CHLOROMETHANE FORMATION IN THE ELECTROLYTIC DECHLORINATION OF TRICHLOROETHYLENE  

EPA Science Inventory

Carbon stable isotope trichloroethylene (13C TCE) was used to investigate the formation of chloromethane (CM) during the electrolytic dechlorination of trichloroethylene (TCE) at a granular-graphite packed cathode. A method was developed to use a conventional GC/MS to ...

142

Kinetics of the Oxidation of Trichloroethylene in Air via Heterogeneous Photocatalysis  

Microsoft Academic Search

Trichloroethylene in solution with air is oxidized rapidly in the presence of irradiated titanium dioxide. Dichloroacetyl chloride (DCAC), which is formed as an intermediate during the trichloroethylene reaction, also undergoes photocatalytic oxidation. This paper describes the kinetics of these reactions and how operating conditions influence the observed reaction rates. Annular photocatalytic reactors with thin films of titanium dioxide catalyst were

W. A. Jacoby; D. M. Blake; R. D. Noble; C. A. Koval

1995-01-01

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

DEVELOPMENT OF A MODEL OF 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 comuination. The...

145

Bacterial treatment system for the remediation of trichloroethylene. Final report, 1 November 1992-31 December 1994  

SciTech Connect

14. Abstract A genetically altered bacterium Burkholderia (Pseudomonas) cepacia PR123 and closely related genetic derivatives were tested for bioreactor and in situ trichloroethylene (TOE) degradation. PRi 23 was shown to degrade TOE in a plugged flow bioreactor, but failed to form a stable biofilm under test conditions at Hanscom AFB. Indigenous microorganisms dominated the reactors shortly after inoculation in every instance, despite changes in support matrix and primary carbon source. The continuous addition of the genetically altered bacterium did achieve a significant (>80%) removal of TOE and cis-dichloroethylene from the waste stream at concentrations of 500-800 ugiL, at 0.26 GPM, thus confirming the capacity the constitutively expressed toluene ortho-monooxygenase (Tom) to cooxidize TOE under environmental conditions. For this reason the Tom constitutive plasmid: TOM31c (a kanamycin resistant derivative of TOM), was transferred to two superior biofilm forming bacteria: P. capacia 17616 and P. sp JSl5O, and dominant aquifer bacterium from Wichita KS WS23. These transconjugants also constitutively degraded TOE, but were no more competitive in biofilm reactors than PR123. In column tests >95% of the TOE was degraded in an 8 hour residence time.

Shields, M.S.

1996-10-01

146

Chemical Kinetic Study of Toluene Oxidation  

SciTech Connect

A study was performed to elucidate the chemical-kinetic mechanism of combustion of toluene. A detailed chemical-kinetic mechanism for toluene was improved by adding a more accurate description of the phenyl + O{sub 2} reaction channels, toluene decomposition reactions and the benzyl + 0 reaction. Results of the chemical kinetic mechanism are compared with experimental data obtained from premixed and nonpremixed systems. Under premixed conditions, predicted ignition delay times are compared with new experimental data obtained in shock tube. Also, calculated species concentration histories are compared to experimental flow reactor data from the literature. Under nonpremixed conditions, critical conditions of extinction and autoignition were measured in strained laminar flows in the counterflow configuration. Numerical calculations are performed using the chemical-kinetic mechanism at conditions corresponding to those in the experiments. Critical conditions of extinction and autoignition are predicted and compared with the experimental data. Comparisons between the model predictions and experimental results of ignition delay times in shock tube, and extinction and autoignition in nonpremixed systems show that the chemical-kinetic mechanism predicts that toluene/air is overall less reactive than observed in the experiments. For both premixed and nonpremixed systems, sensitivity analysis was used to identify the reaction rate constants that control the overall rate of oxidation in each of the systems considered. Under shock tube conditions, the reactions that influence ignition delay time are H + O{sub 2} chain branching, the toluene decomposition reaction to give an H atom, and the toluene + H abstraction reaction. The reactions that influence autoignition in nonpremixed systems involve the benzyl + HO{sub 2} reaction and the phenyl + O{sub 2} reaction.

Pitz, W J; Seiser, R; Bozzelli, J W; Seshadri, K; Chen, C-J; Da Costa, I; Fournet, R; Billaud, F; Battin-Leclerc, F; Westbrook, C K

2001-12-17

147

Neurobehavioral performance in workers exposed to toluene.  

PubMed

Toluene is widely used in adhesive, printing, painting and petroleum industries in many countries. This study was conducted to examine the effect of chronic exposure to toluene below 100ppm on neurobehavioral performance using a computerized neurobehavioral test battery that emphasizes simple instructions and practice prior to testing. The Behavioral Assessment and Research System (BARS) with Korean language instructions was administered to 54 workers from three different industries: oil refinery, gravure printing, and rubber boat manufacturing. The battery consisted of the following tests: Digit Span (DS), Simple Reaction Time (SRT), Selective Attention (SAT), Finger Tapping (FT), and Symbol Digit (SD). Urine was collected at the end-of-shift to analyze urinary hippuric acid to assess exposure level to toluene. Based on the previous air toluene level, workers were divided into three groups: Low (21 workers, less than 10ppm), Moderate (13 workers, 20-30ppm) and High (20 workers, 70-80ppm) exposure status. Analysis of Covariance (ANCOVA) adjusting for age, education and work duration as covariates, was performed to examine the relationship between the neurobehavioral performance and the exposure groups. Poorer performance of the High exposure group was found on FT-preferred (F=7.034, p=0.002) and SAT latency (F=11.710, p=0.000). Age showed a significant correlation with SD (r=0.417, p=0.002) and SAT number correct (r=-0.460, p=0.000). Years of education and work duration were not significantly correlated with any items. This study supports that toluene exposure below 100ppm is associated with neurobehavioral changes and that high-level toluene exposure could cause not only attention and concentration, but also motor performance deficits. PMID:21783537

Kang, Seong-Kyu; Rohlman, Diane S; Lee, Mi-Young; Lee, Hye-Sil; Chung, Soo-Young; Anger, W Kent

2005-05-01

148

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

149

Drinking Water Criteria Document for Toluene (Final Draft).  

National Technical Information Service (NTIS)

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 toxicoki...

J. M. Becker M. W. Neal

1985-01-01

150

Drinking Water Criteria Document for Toluene (Final), March 1987,  

National Technical Information Service (NTIS)

The Office of Drinking Water (ODW), Environmental Protection Agency has prepared a Drinking Water Criteria Document on Toluene. This Criteria Document is an extensive review of the following topics: Physical chemical properties of Toluene; Toxicokinetics ...

J. M. Becker M. W. Neal

1987-01-01

151

Toluene exposure increases aminophylline-induced seizure susceptibility in mice.  

PubMed

The effects of toluene on the sensitivity to seizures induced by aminophylline were investigated. Mice were pretreated with an ip injection of corn oil or toluene (100-500 mg/kg) followed by a timed intravenous infusion of aminophylline at various time intervals to assess the seizure thresholds and lethal doses. Toluene increased seizure susceptibility to aminophylline in a dose- and time-dependent manner. Toluene-induced enhancement of seizure susceptibility to aminophylline occurred as early as 30 min and persisted for at least 3 days after a single administration of toluene (500 mg/kg). Treatment of benzaldehyde, one of toluene's metabolites, also showed an increase in the susceptibility to aminophylline. The enhancing effect was also observed in caffeine-induced seizures 1 h, but not 1 day after toluene treatment. These results suggest that individuals with toluene exposure may increase the risk for convulsive and even lethal complications associated with the therapeutic use of aminophylline. PMID:14644630

Chan, Ming-Huan; Chen, Hwei-Hsien

2003-12-01

152

Toluene Monooxygenase-Catalyzed Epoxidation of Alkenes  

PubMed Central

Several toluene monooxygenase-producing organisms were tested for their ability to oxidize linear alkenes and chloroalkenes three to eight carbons long. Each of the wild-type organisms degraded all of the alkenes that were tested. Epoxides were produced during the oxidation of butene, butadiene, and pentene but not hexene or octadiene. A strain of Escherichia coli expressing the cloned toluene-4-monooxygenase (T4MO) of Pseudomonas mendocina KR1 was able to oxidize butene, butadiene, pentene, and hexene but not octadiene, producing epoxides from all of the substrates that were oxidized. A T4MO-deficient variant of P. mendocina KR1 oxidized alkenes that were five to eight carbons long, but no epoxides were detected, suggesting the presence of multiple alkene-degrading enzymes in this organism. The alkene oxidation rates varied widely (ranging from 0.01 to 0.33 ?mol of substrate/min/mg of cell protein) and were specific for each organism-substrate pair. The enantiomeric purity of the epoxide products also varied widely, ranging from 54 to >90% of a single epoxide enantiomer. In the absence of more preferred substrates, such as toluene or alkenes, the epoxides underwent further toluene monooxygenase-catalyzed transformations, forming products that were not identified.

McClay, Kevin; Fox, Brian G.; Steffan, Robert J.

2000-01-01

153

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...

154

Sources, Emission and Exposure for Trichloroethylene(TCE) and Related Chemicals.  

National Technical Information Service (NTIS)

This report is an exposure assessment of Trichloroethylene (TCE), its metabolites, and other chemical compounds known to produce identical metabolites. In addition to TCE, other parent compounds considered here are 1,1,1-trichloroethane (methyl chloroform...

2001-01-01

155

COMPARISON OF MINERAL AND SOLUBLE IRON FENTON'S CATALYSTS FOR THE TREATMENT OF TRICHLOROETHYLENE. (R826163)  

EPA Science Inventory

Abstract Contaminant degradation, stoichiometry, and role of hydroxyl radicals (OH·) in four Fenton's systems were investigated using trichloroethylene (TCE) as a model contaminant. A standard Fenton's system, a modified soluble iron system with a...

156

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

157

Physiologically Based Pharmacokinetic Models for the Transport of Trichloroethylene in Adipose Tissue.  

National Technical Information Service (NTIS)

In this paper we present three physiologically based pharmacokinetic (PBPK) models for the systemic transport of trichloroethylene (TCE), with a focus on the adipose, or fat tissue. TCE is a widespread environmental contaminant, and has been shown to prod...

R. A. Albanese H. T. Banks M. V. Evans L. K. Potter

2001-01-01

158

HEALTH ASSESSMENT DOCUMENT FOR TRICHLOROETHYLENE : SYNTHESIS AND CHARACTERIZATION (EXTERNAL REVIEW DRAFT)  

EPA Science Inventory

This assessment presents EPA's most current evaluation of the potential health risks from exposure to trichloroethylene (TCE). TCE exposure is associated with several adverse health effects, including neurotoxicity, immunotoxicity, developmental toxicity, liver toxicity, kidney t...

159

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...

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 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...

162

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...

163

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...

164

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...

165

DEGRADATION OF TRICHLOROETHYLENE UNDER HIGH-TEMPERATURE THERMAL SOURCE-ZONE REMOVAL CONDITIONS (POSTER PRESENTATION)  

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

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...

167

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...

168

MODELING THE ELECTROLYTIC DECHLORINATION OF TRICHLOROETHYLENE IN A GRANULAR GRAPHITE-PACKED REACTOR  

EPA Science Inventory

A comprehensive reactor model was developed for the electrolytic dechlorination of trichloroethylene (TCE) at a granular-graphite cathode. The reactor model describes the dynamic processes of TCE dechlorination and adsorption, and the formation and dechlorination of all the major...

169

Development and Validation of Methods for Applying Pharmacokinetic Data in Risk Assessment. Volume 2. Trichloroethylene.  

National Technical Information Service (NTIS)

This volume describes the design, development and execution of physiologically based pharmacokinetic modeling as they apply to trichloroethylene (TCE) exposure in humans. Emphasis is also on TCE metabolites, trichloroacetic acid (TCA). PBPK human models f...

1990-01-01

170

Removal of Trichloroethylene Contamination from Drinking Water at a USAF Installation.  

National Technical Information Service (NTIS)

Trichloroethylene (TCE), a solvent previously used by numerous USAF industrial activities as a degreasing agent, was discovered in relatively high concenrations in the drinking water distribution system at one USAF installation. Various USAF agencies and ...

R. G. Perry

1978-01-01

171

TRICHLOROETHYLENE ADSORPTION BY ACTIVATED CARBON PRELOADED WITH HUMIC SUBSTANCES: EFFECTS OF SOLUTION CHEMISTRY. (R828157)  

EPA Science Inventory

Abstract Trichloroethylene (TCE) adsorption by activated carbon previously loaded ("preloaded") with humic substances was found to decrease with increasing concentrations of monovalent ions (NaCl), calcium (until solubility was exceeded), or dissolved oxygen in...

172

Benzene\\/toluene\\/ p -xylene degradation. Part II. Effect of substrate interactions and feeding strategies in toluene\\/benzene and toluene\\/ p -xylene fermentations in a partitioning bioreactor  

Microsoft Academic Search

A two-phase aqueous\\/organic partitioning bioreactor scheme was used to degrade mixtures of toluene and benzene, and toluene\\u000a and p-xylene, using simultaneous and sequential feeding strategies. The aqueous phase of the partitioning bioreactor contained\\u000a Pseudomonas sp. ATCC 55595, an organism able to degrade benzene, toluene and p-xylene simultaneously. An industrial grade of oleyl alcohol served as the organic phase. In each

L. D. Collins; A. J. Daugulis

1999-01-01

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

Decomposition characteristics of toluene by a corona radical shower system.  

PubMed

Non-thermal plasma technologies offer an innovative approach to decomposing various volatile organic compounds(VOCs). The decomposition of toluene from simulated flue gas was investigated using a pipe electrode with nozzles for the generation of free radicals. Corona characteristics and decomposition of toluene were investigated experimentally. In addition, the decomposition mechanism of toluene was explored in view of reaction rate. The experimental results showed that the humidity of additional gas has an important effect on corona characteristics and modes and stable streamer corona can be generated through optimizing flow rate and humidity of additional gas. Applied voltage, concentration of toluene, humidity of toluene and resident time are some important factors affecting decomposition efficiency. Under optimizing conditions, the decomposition efficiency of toluene can reach 80%. These results can give a conclusion that the corona radical shower technology is feasible and effective on the removal of toluene in the flue gas. PMID:15495952

Wu, Zu-liang; Gao, Xiang; Luo, Zhong-yang; Ni, Ming-jiang; Cen, Ke-fa

2004-01-01

175

Health risk assessment of trichloroethylene (TCE) in California drinking water  

SciTech Connect

This document presents an assessment of the potential health risks associated with exposure to trichloroethylene (TCE) dissolved in California drinking waters. This assessment is being provided to the California Department of Health Services (CDHS) for the development of drinking-water standards to manage the health risks of TCE exposures. Other assessments required in the risk-management process include analyses of the technical and economic feasibility of treating water supplies contaminated with TCE. A primary goal of this health-risk assessment is to evaluate dose-response relationships for observed and potential toxic end points of TCE in order to define dose rates that can be used to establish standards that will protect members of the general public from adverse health effects resulting solely from water-based exposures to TCE. We also analyze the extent of human exposures attributable to TCE-contaminated groundwater in California. 363 refs., 8 figs., 22 tabs.

Bogen, K.T.; Hall, L.C.; Perry, L.; Fish, R.; McKone, T.E.; Dowd, P.; Patton, S.E.; Mallon, B.

1988-01-28

176

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

177

Trichloroethylene transformation in aerobic pyrite suspension: pathways and kinetic modeling.  

PubMed

The pathways and kinetics of trichloroethylene (TCE) degradation in aerobic pyrite suspension were investigated. The detection of hydroxyl radical in aqueous pyrite suspension suggested that TCE was degraded by this strong oxidant The reaction pathways of TCE degradation were proposed in which the degradation of TCE to formic acid and finally to CO2 was the main route. Degradation of TCE to oxalic acid and to dichloroacetic acid were found as minor pathways. Degradation rates of TCE to formic acid, glyoxylic acid, and dichloroacetic acid were obtained using kinetic model at 1.2 x 10(-2), 9.8 x 10(-4) and 4.6 x 10(-4) h(-1), respectively. PMID:19764244

Pham, Hoa T; Suto, Koichi; Inoue, Chihiro

2009-09-01

178

Water-in-trichloroethylene emulsions stabilized by uniform carbon microspheres.  

PubMed

Uniform hard carbon spheres (HCS), synthesized by the hydrothermal decomposition of sucrose followed by pyrolysis, are effective at stabilizing water-in-trichloroethylene (TCE) emulsions. The irreversible adsorption of carbon particles at the TCE-water interface resulting in the formation of a monolayer around the water droplet in the emulsion phase is identified as the key reason for emulsion stability. Cryogenic scanning electron microscopy was used to image the assembly of carbon particles clearly at the TCE-water interface and the formation of bilayers in regions of droplet-droplet contact. The results of this study have potential implications to the subsurface injection of carbon submicrometer particles containing zero-valent iron nanoparticles to treat pools of chlorinated hydrocarbons that are sequestered in fractured bedrock. PMID:22181984

Venkataraman, Pradeep; Sunkara, Bhanukiran; St Dennis, J E; He, Jibao; John, Vijay T; Bose, Arijit

2012-01-17

179

Trichloroethylene biodegradation by phenoloxidizing cultures grown from various conditions.  

PubMed

The rate and extent of trichloroethylene (TCE) degradation by three cultures of phenol oxidizing bacteria grown from two chemostats and one from rotating biological contactors was investigated. Batch experiments were performed to measure the disappearance of TCE both with the resting cell alone and with the formate added. Experimental data were then compared with mathematical predictions from a model describing TCE transformation. Through nonlinear regression analysis, a best fit between the measurements and predictions was achieved when residual sum of squares reached a minimum. Based on the resultant parameters of transformation capacity and reaction rate, the suspended cells with a mean cell retention time (MCRT) of 3.8 days were the most active in degrading TCE, while the attached bacteria had the least activity. Based on the results presented herein, it is recommend that using suspended-growth reactors operated at short MCRT to produce desirable cells for cometablic transformation of TCE. PMID:9830134

Lee, C Y; Cheng, S Z

1998-11-01

180

Effects of dynamic redox zonation on the potential for natural attenuation of trichloroethylene at a fire-training-impacted aquifer  

USGS Publications Warehouse

Hydrogeochemical and microbiological methods were used to characterize temporal changes along a transect of an aquifer contaminated by mixed hydrocarbon and solvent wastes from fire training activities at Wurtsmith Air Force Base (Oscoda, MI). Predominant terminal electron accepting processes (TEAPs) as measured by dissolved hydrogen indicated reoxygenation along the transect between October 1995 and October 1996, possibly because of recharge, fluctuations in water table elevation, or microbial activity. Microbiological analyses using universal and archaeal probes revealed a relationship between groundwater hydrogen concentration, TEAP, and predominant bacterial phylogeny. Specifically, a raised water table level and evidence of methanogenesis corresponded to an order of magnitude increase in archaeal 16S rRNA relative to when this zone was unsaturated. Spatial microbial and geochemical dynamics did not result in measurable differences in trichloroethylene (TCE) mineralization potential in vadose, capillary fringe, and saturated zone soils during a 500-day microcosm experiment using unprocessed contaminated soil and groundwater. Aerobic systems indicated that methane, but not toluene, may serve as cosubstrate for TCE cometabolism. Anaerobic microcosms demonstrated evidence for methanogenesis, CO2 production and hydrogen consumption, yet dechlorination activity was only observed in a microcosm with sulfate-reduction as the dominant TEAP. Mass balance calculations indicated less than 5% mineralization, regardless of redox zone or degree of saturation, at maximum rates of 0.01-0.03 ??mol/g soil??d. The general lack of dechlorination activity under laboratory conditions corroborates the limited evidence for natural dechlorination at this site, despite abundant electron donor material and accumulated organic acids from microbial degradation of alkylbenzenes. Thus, the short-term temporal dynamics in redox conditions is unlikely to have measurable effects on the long-term natural remediation potential of the aquifer.

Skubal, K. L.; Haack, S. K.; Forney, L. J.; Adriaens, P.

1999-01-01

181

Microwave spectrum of the 13C-ring-monosubstituted toluenes and structure of toluene  

NASA Astrophysics Data System (ADS)

The microwave spectra of the four 13C-ring-monosubstituted toluene species were analyzed in the frequency range 18.5-40 GHz and their rotational constants calculated. From these data and previous work, a substitution structure and a least-squares structure were calculated and are discussed. The microwave structure of toluene, in good agreement with recent electron diffraction results, presents the following features: a slight elongation of the phenyl ring along the symmetry axis, a corresponding small narrowing of the ring, and a short C ring?C methyl bond.

Amir-Ebrahimi, V.; Choplin, A.; Demaison, J.; Roussy, G.

1981-09-01

182

Tetrachloroethylene in drinking water and birth outcomes at the US Marine Corps Base at Camp Lejeune, North Carolina.  

PubMed

A study of mean birth weight, small-for-gestational-age infants, and preterm birth was conducted at the US Marine Corps Base at Camp Lejeune, North Carolina, where drinking water was contaminated with volatile organic compounds. Tetrachloroethylene (PCE) was the predominant contaminant. The authors used multiple linear and logistic regression to analyze 1968-1985 data from 11,798 birth certificates. Overall, at most weak associations were observed between PCE exposure and study outcomes. However, associations were found between PCE exposure and birth-weight outcomes for infants of older mothers and mothers with histories of fetal loss. Adjusted mean birth-weight differences between PCE-exposed and unexposed infants were -130 g (90% confidence interval (CI): -236, -23) for mothers aged 35 years or older and -104 g (90% CI: -174, -34) for mothers with two or more previous fetal losses. Adjusted odds ratios for PCE exposure and small-for-gestational-age infants were 2.1 (90% CI: 0.9, 4.9) for older mothers and 2.5 (90% CI: 1.5, 4.3) for mothers with two or more prior fetal losses. These results suggest that some fetuses may be more vulnerable than others to chemical insult. PMID:11700244

Sonnenfeld, N; Hertz-Picciotto, I; Kaye, W E

2001-11-15

183

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...

184

Substrate- and nutrient-limited toluene biotransformation in sandy soil  

SciTech Connect

Lab microcosm tests of the rate of toluene biodegradation were performed using soil from the A, B, and C horizons of the unsaturated zone of a sandy field site. Toluene biodegradation was rapid, occurring at a time scale comparable to the rate of sorption in many of the microcosms and demonstrating the potential for bioremediation of these contaminants in unsaturated soil. In the A horizon, with an initial toluene concentration in the solution phase of 4.5 mg/L, degradation was controlled by substrate-limited growth on toluene as the primary substrate. Soil from the B and C horizons initially showed similar behavior with a lower toluene concentrations of about 2.5 mg/L. The maximum utilization rate ([mu][sub max]) for soil from all three depths was 2.0 d[sup [minus]1]. With repeated exposure to moderate to high concentrations of toluene, transformation in the B- and C-horizon soil appeared to be zero order, at a rate of 1.0 to 2.0 [mu]g toluene/g soil/d. In C-horizon soil that had been taken directly from the field, the transformation rate was almost immeasurably slow. Addition of nitrogens as either ammonium or nitrate accelerated the degradation, showing that nitrogen was the most limiting nutrient. The apparent adaptation period observed before rapid toluene removal was fit by a substrate-limited growth model. Greater numbers of toluene-degrading microorganisms were found in soil exposed to toluene than in unexposed soil, supporting biomass growth as the explanation for the adaptation period. The results of enumeration of heterotrophs compared to the numbers of toluene degraders suggested that a small proportion to the total viable microorganisms were responsible for degradation of toluene.

Allen-King, R.M. (Washington State Univ., Pullman, WA (United States). Dept. of Geology); Barker, J.F.; Gillham, R.W. (Univ. of Waterloo, Ontario (Canada). Waterloo Centre for Groundwater Research); Jensen, B.K. (Water Quality Inst., Horsholm (Denmark). Environmental Biotechnology Section)

1994-05-01

185

Adaptation of Rhodococcus erythropolis cells to high concentrations of toluene  

Microsoft Academic Search

Cells of Rhodococcus erythropolis DCL14 were adapted to increasing toluene concentrations in a mechanically stirred reactor. When the initial non-adapted cells\\u000a were placed in contact with toluene, only 10.5% of cells remained viable after 1 h in the presence of 20% (v\\/v) toluene, while 8.6% of cells were viable after 28 h in the presence of an organic phase containing 80% (v\\/v)

Vanessa Fatal; Sebastião S. Alves; M. Manuela R. da Fonseca

2007-01-01

186

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

187

Anaerobic degradation of toluene by a denitrifying bacterium.  

PubMed Central

A denitrifying bacterium, designated strain T1, that grew with toluene as the sole source of carbon under anaerobic conditions was isolated. The type of agar used in solid media and the toxicity of toluene were determinative factors in the successful isolation of strain T1. Greater than 50% of the toluene carbon was oxidized to CO2, and 29% was assimilated into biomass. The oxidation of toluene to CO2 was stoichiometrically coupled to nitrate reduction and denitrification. Strain T1 was tolerant of and grew on 3 mM toluene after a lag phase. The rate of toluene degradation was 1.8 mumol min-1 liter-1 (56 nmol min-1 mg of protein-1) in a cell suspension. Strain T1 was distinct from other bacteria that oxidize toluene anaerobically, but it may utilize a similar biochemical pathway of oxidation. In addition, o-xylene was transformed to a metabolite in the presence of toluene but did not serve as the sole source of carbon for growth of strain T1. This transformation was dependent on the degradation of toluene. Images

Evans, P J; Mang, D T; Kim, K S; Young, L Y

1991-01-01

188

Anaerobic degradation of toluene by a denitrifying bacterium  

SciTech Connect

A denitrifying bacterium, designated strain T1, that grew with toluene as the sole source of carbon under anaerobic conditions was isolated. The type of agar used in solid media and the toxicity of toluene were determinative factors in the successful isolation of strain T1. Greater than 50% of the toluene carbon was oxidized to CO{sub 2}, and 29% was assimilated into biomass. The oxidation of toluene to CO{sub 2} was stoichiometrically coupled to nitrate reduction and denitrification. Strain T1 was tolerant of and grew on 3 mM toluene after a lag phase. The rate of toluene degradation was 1.8 {mu}mol min{sup {minus}1} liter{sup {minus}1} (56 nmol min{sup {minus}1} mg of protein{sup {minus}1}) in a cell suspension. Strain T1 was distinct from other bacteria that oxidize toluene anaerobically, but it may utilize a similar biochemical pathway of oxidation. In addition, o-xylene was transformed to a metabolite in the presence of toluene but did not serve as the sole source of carbon for growth of strain T1. This transformation was dependent on the degradation of toluene.

Evans, P.J.; Mang, D.T.; Kwang Shin Kim; Young, L.Y. (New York Univ. Medical Center, NY (United States))

1991-04-01

189

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

190

UV photolysis of trichloroethylene: product study and kinetic modeling.  

PubMed

Direct UV photolysis of trichloroethylene (TCE) in dilute aqueous solution generated chloride ions as a major end product and several reaction intermediates, such as formic acid, di- and monochloroacetic acids, glyoxylic acid, and, to a lesser extent, mono- and dichloroacetylene, formaldehyde, dichloroacetaldehyde, and oxalic acid. Under prolonged irradiation, these byproducts underwent photolysis, and a high degree of mineralization (approximately 95%) was achieved. TCE decays through the following major pathways: (1) TCE + h nu --> ClCH=C*Cl + Cl*; (2) TCE (H2O) + h nu --> ClCH(OH)-CHCl2; (3) TCE + h nu --> HC[triple bond]CCl + Cl2; (4) TCE + h nu --> ClC[triple bond]CCl + HCl; (5) TCE + Cl* --> Cl2HC-C*Cl2. A kinetic model was developed to simulate the destruction of TCE and the formation and fate of byproducts in aqueous solution under irradiation with polychromatic light. By fitting the experimental data, the quantum yields for the four photolysis steps were predicted as phi(1) = 0.13, phi(2) = 0.1, phi(3) = 0.032, and phi(4) = 0.092, respectively. The reaction mechanism proposed for the photodegradation of TCE accounts for all intermediates that were detected. The agreement between the computed and experimental patterns of TCE and reaction products is satisfactory given the complexity of the reaction mechanism and the lack of photolytic kinetic parameters that are provided in the literature. PMID:15669328

Li, Ke; Stefan, Mihaela I; Crittenden, John C

2004-12-15

191

Trichloroethylene Cancer Epidemiology: A Consideration of Select Issues  

PubMed Central

A large body of epidemiologic evidence exists for exploring causal associations between cancer and trichloroethylene (TCE) exposure. The U.S. Environmental Protection Agency 2001 draft TCE health risk assessment concluded that epidemiologic studies, on the whole, support associations between TCE exposure and excess risk of kidney cancer, liver cancer, and lymphomas, and, to a lesser extent, cervical cancer and prostate cancer. As part of a mini-monograph on key issues in the health risk assessment of TCE, this article reviews recently published scientific literature examining cancer and TCE exposure and identifies four issues that are key to interpreting the larger body of epidemiologic evidence: a) relative sensitivity of cancer incidence and mortality data; b) different classifications of lymphomas, including non-Hodgkin lymphoma; c) differences in data and methods for assigning TCE exposure status; and d) different methods employed for causal inferences, including statistical or meta-analysis approaches. The recent epidemiologic studies substantially expand the epidemiologic database, with seven new studies available on kidney cancer and somewhat fewer studies available that examine possible associations at other sites. Overall, recently published studies appear to provide further support for the kidney, liver, and lymphatic systems as targets of TCE toxicity, suggesting, as do previous studies, modestly elevated (typically 1.5–2.0) site-specific relative risks, given exposure conditions in these studies. However, a number of challenging issues need to be considered before drawing causal conclusions about TCE exposure and cancer from these data.

Scott, Cheryl Siegel; Chiu, Weihsueh A.

2006-01-01

192

Health risk assessment of environmental exposure to trichloroethylene  

SciTech Connect

A review of the animal data showed trichloroethylene (TRI) to be of low acute toxicity. Repeated exposure showed that the target organs were the liver, and to a lesser extent, the kidney. TRI is not mutagenic or only marginally mutagenic. There is no evidence of fetotoxicity or teratogenicity. TRI is judged not to exhibit chronic neurotoxicity. Lifetime bioassays resulted in tumors in both the mouse and the rat. However, because of qualitative and quantitative metabolic differences between rodent and human, no one suitable tumor site can be chosen for human health risk assessment. In addition, of the several epidemiology studies, none has demonstrated a positive association for increased tumor incidence. A review of the health effects in humans shows TRI to be of low acute toxicity and, following chronic high doses, to be hepatotoxic. Environmental exposure to TRI is mainly via the atmosphere, while the contribution from exposure to drinking water and foodstuffs is negligible. The total body burden was calculated as 22 micrograms/day. The safety margin approach based on human health effects showed that TRI levels are well within the safety margin for the human no-observable-effect level (10,000 times lower). The total body burden represents a risk of 1.4 X 10(-5) by linearized multistage modeling. Therefore, by either methodological approach to risk assessment, the environmental occurrence of TRI does not represent a significant health risk to the general population or to the population in areas close to industrial activities. 66 references.

Brown, L.P.; Farrar, D.G.; de Rooij, C.G. (Epidemiology Unit, Alderley Park, Macclesfield, Cheshire (England))

1990-02-01

193

Key Scientific Issues in the Health Risk Assessment of Trichloroethylene  

PubMed Central

Trichloroethylene (TCE) is a common environmental contaminant at hazardous waste sites and in ambient and indoor air. Assessing the human health risks of TCE is challenging because of its inherently complex metabolism and toxicity and the widely varying perspectives on a number of critical scientific issues. Because of this complexity, the U.S. Environmental Protection Agency (EPA) drew upon scientific input and expertise from a wide range of groups and individuals in developing its 2001 draft health risk assessment of TCE. This scientific outreach, which was aimed at engaging a diversity of perspectives rather than developing consensus, culminated in 2000 with 16 state-of-the-science articles published together as an Environmental Health Perspectives supplement. Since that time, a substantial amount of new scientific research has been published that is relevant to assessing TCE health risks. Moreover, a number of difficult or controversial scientific issues remain unresolved and are the subject of a scientific consultation with the National Academy of Sciences coordinated by the White House Office of Science and Technology Policy and co-sponsored by a number of federal agencies, including the U.S. EPA. The articles included in this mini-monograph provide a scientific update on the most prominent of these issues: the pharmacokinetics of TCE and its metabolites, mode(s) of action and effects of TCE metabolites, the role of peroxisome proliferator–activated receptor in TCE toxicity, and TCE cancer epidemiology.

Chiu, Weihsueh A.; Caldwell, Jane C.; Keshava, Nagalakshmi; Scott, Cheryl Siegel

2006-01-01

194

Issues in the Pharmacokinetics of Trichloroethylene and Its Metabolites  

PubMed Central

Much progress has been made in understanding the complex pharmacokinetics of trichloroethylene (TCE). Qualitatively, it is clear that TCE is metabolized to multiple metabolites either locally or into systemic circulation. Many of these metabolites are thought to have toxicologic importance. In addition, efforts to develop physiologically based pharmacokinetic (PBPK) models have led to a better quantitative assessment of the dosimetry of TCE and several of its metabolites. As part of a mini-monograph on key issues in the health risk assessment of TCE, this article is a review of a number of the current scientific issues in TCE pharmacokinetics and recent PBPK modeling efforts with a focus on literature published since 2000. Particular attention is paid to factors affecting PBPK modeling for application to risk assessment. Recent TCE PBPK modeling efforts, coupled with methodologic advances in characterizing uncertainty and variability, suggest that rigorous application of PBPK modeling to TCE risk assessment appears feasible at least for TCE and its major oxidative metabolites trichloroacetic acid and trichloroethanol. However, a number of basic structural hypotheses such as enterohepatic recirculation, plasma binding, and flow- or diffusion-limited treatment of tissue distribution require additional evaluation and analysis. Moreover, there are a number of metabolites of potential toxicologic interest, such as chloral, dichloroacetic acid, and those derived from glutathione conjugation, for which reliable pharmacokinetic data is sparse because of analytical difficulties or low concentrations in systemic circulation. It will be a challenge to develop reliable dosimetry for such cases.

Chiu, Weihsueh A.; Okino, Miles S.; Lipscomb, John C.; Evans, Marina V.

2006-01-01

195

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

196

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

197

Optimization of electrochemical dechlorination of trichloroethylene in reducing electrolytes.  

PubMed

Electrochemical dechlorination of trichloroethylene (TCE) in aqueous solution is investigated in a closed, liquid-recirculation system. The anodic reaction of cast iron generates ferrous species, creating a chemically reducing electrolyte (negative ORP value). The reduction of TCE on the cathode surface is enhanced under this reducing electrolyte because of the absence of electron competition. In the presence of the iron anode, the performances of different cathodes are compared in a recirculated electrolysis system. The copper foam shows superior capability for dechlorination of aqueous TCE. Electrolysis by cast iron anode and copper foam cathode is further optimized though a multivariable experimental design and analysis. The conductivity of the electrolyte is identified as an important factor for both final elimination efficiency (FEE) of TCE and specific energy consumption. The copper foam electrode exhibits high TCE elimination efficiency in a wide range of initial TCE concentration. Under coulostatic conditions, the optimal conditions to achieve the highest FEE are 9.525 mm thick copper foam electrode, 40 mA current and 0.042 mol L(-1) Na(2)SO(4). This novel electrolysis system is proposed to remediate groundwater contaminated by chlorinated organic solvents, or as an improved iron electrocoagulation process capable of treating the wastewater co-contaminated with chlorinated compounds. PMID:22264798

Mao, Xuhui; Ciblak, Ali; Baek, Kitae; Amiri, Mohammad; Loch-Caruso, Rita; Alshawabkeh, Akram N

2012-04-15

198

Trichloroethylene: Mechanistic, epidemiologic and other supporting evidence of carcinogenic hazard.  

PubMed

The chlorinated solvent trichloroethylene (TCE) is a ubiquitous environmental pollutant. The carcinogenic hazard of TCE was the subject of a 2012 evaluation by a Working Group of the International Agency for Research on Cancer (IARC). Information on exposures, relevant data from epidemiologic studies, bioassays in experimental animals, and toxicity and mechanism of action studies was used to conclude that TCE is carcinogenic to humans (Group 1). This article summarizes the key evidence forming the scientific bases for the IARC classification. Exposure to TCE from environmental sources (including hazardous waste sites and contaminated water) is common throughout the world. While workplace use of TCE has been declining, occupational exposures remain of concern, especially in developing countries. The strongest human evidence is from studies of occupational TCE exposure and kidney cancer. Positive, although less consistent, associations were reported for liver cancer and non-Hodgkin lymphoma. TCE is carcinogenic at multiple sites in multiple species and strains of experimental animals. The mechanistic evidence includes extensive data on the toxicokinetics and genotoxicity of TCE and its metabolites. Together, available evidence provided a cohesive database supporting the human cancer hazard of TCE, particularly in the kidney. For other target sites of carcinogenicity, mechanistic and other data were found to be more limited. Important sources of susceptibility to TCE toxicity and carcinogenicity were also reviewed by the Working Group. In all, consideration of the multiple evidence streams presented herein informed the IARC conclusions regarding the carcinogenicity of TCE. PMID:23973663

Rusyn, Ivan; Chiu, Weihsueh A; Lash, Lawrence H; Kromhout, Hans; Hansen, Johnni; Guyton, Kathryn Z

2014-01-01

199

Intrinsic bioremediation of trichloroethylene and chlorobenzene: field and laboratory studies.  

PubMed

Activities at a former fire training area at Robins Air Force Base in Georgia, USA resulted in contamination of groundwater with a mixture of trichloroethylene (TCE) and chlorobenzene (CB). Results from the field investigation suggest that intrinsic bioremediation process is occurring, which caused the decrease in TCE and CB concentrations, and increase in TCE degradation byproducts [e.g., dichloroethylene isomers (DCEs), vinyl chloride (VC)] concentrations. Contaminated groundwater samples collected from this site were used to conduct microbial enumeration tests, and used as the inocula for microcosm establishment. Results from the microbial enumeration study indicate that methanogenesis was the dominant biodegradation pattern within the source and mid-plume areas, and the aerobic biodegradation process dominated the downgradient area. Laboratory microcosm experiments were conducted to evaluate the feasibility of using CB as the primary substrate to enhance the intrinsic biodegradation of TCE. Microcosm results suggest that CB can serve as the primary substrate (electron donor), and enhance TCE biodegradation to less-chlorinated compounds under both aerobic cometabolism and reductive dechlorination conditions. PMID:10502607

Kao, C M; Prosser, J

1999-10-01

200

Optimization of electrochemical dechlorination of trichloroethylene in reducing electrolytes  

PubMed Central

Electrochemical dechlorination of trichloroethylene (TCE) in aqueous solution is investigated in a closed, liquid-recirculation system. The anodic reaction of cast iron generates ferrous species, creating a chemically reducing electrolyte (negative ORP value). The reduction of TCE on the cathode surface is enhanced under this reducing electrolyte because of the absence of electron competition. In the presence of the iron anode, the performances of different cathodes are compared in a recirculated electrolysis system. The copper foam shows superior capability for dechlorination of aqueous TCE. Electrolysis by cast iron anode and copper foam cathode is further optimized though a multivariable experimental design and analysis. The conductivity of the electrolyte is identified as an important factor for both final elimination efficiency (FEE) of TCE and specific energy consumption. The copper foam electrode exhibits high TCE elimination efficiency in a wide range of initial TCE concentration. Under coulostatic conditions, the optimal conditions to achieve the highest FEE are 9.525 mm thick copper foam electrode, 40 mA current and 0.042 mol L?1 Na2SO4. This novel electrolysis system is proposed to remediate groundwater contaminated by chlorinated organic solvents, or as an improved iron electrocoagulation process capable of treating the wastewater co-contaminated with chlorinated compounds.

Mao, Xuhui; Ciblak, Ali; Baek, Kitae; Amiri, Mohammad; Loch-Caruso, Rita; Alshawabkeh, Akram N.

2012-01-01

201

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

202

Chemical Kinetic Characterization of Combustion Toluene  

SciTech Connect

A study is performed to elucidate the chemical kinetic mechanism of combustion of toluene. A detailed chemical kinetic mechanism for toluene was improved by adding a more accurate description of the phenyl + O{sub 2} reaction channels. Results of the chemical kinetic mechanism are compared with experimental data obtained from premixed and nonpremixed systems. Under premixed conditions, predicted ignition delay times are compared with new experimental data obtained in shock tube. Also, calculated species concentration histories are compared to experimental flow reactor data from the literature. Critical conditions of extinction and ignition were measured in strained laminar flows under nonpremixed conditions in the counterflow configuration. Numerical calculations are performed using the chemical kinetic mechanism at conditions corresponding to those in the experiments. Critical conditions of extinction and ignition are predicted and compared with the experimental data. For both premixed and nonpremixed systems, sensitivity analysis was used to identify the reaction rate constants that control the overall rate of oxidation in each of the systems considered.

Pitz, W J; Seiser, R; Bozzelli, J W; Da Costa, I; Fournet, R; Billaud, F; Battin-Leclerc, F; Seshadri, K; Westbrook, C K

2001-03-20

203

Biofiltration of air contaminated with toluene.  

PubMed

In industrial activities, operation of air biofilters may be interrupted for a long period of time. In order to examine the effect of shut-down on the performance of biofilters, a pilot scale biofiltration unit was restarted up after a non-use duration of eight months. After a reacclimation period of eight days, the biofilter reached an elimination capacity of 35 g x m(-3) x h(-1) compared to 38 g x m(-3) x h(-1) before shut-down, for the same operating conditions. The results obtained indicate that the microorganism activity was completely restored and this was confirmed by the microbial count tests performed on filter bed material samples. The impact of varying the inlet concentration of toluene on biofilter performance was also investigated. A maximum elimination capacity of 120 g x m(-3) x h(-1) was achieved, compared to 135 g x m(-3) x h(-1) before shut-down. The biofilter removal efficiency exceeded 96% for inlet concentrations up to 1.8 g x m(-3). Temperature measurements revealed that the filter bed temperature depends strongly on the intensity of microbial activity and the biofilter effectiveness in eliminating toluene. Experimental data were compared with the calculations of a mathematical model. Comparison showed that the theoretical model was successful in predicting the performance of the biofiltration unit. PMID:11561950

Elmrini, H; Kerdouss, F; Jorio, H; Heitz, M

2001-08-01

204

Directed Evolution of Toluene ortho-Monooxygenase for Enhanced 1-Naphthol Synthesis and Chlorinated Ethene Degradation  

PubMed Central

Trichloroethylene (TCE) is the most frequently detected groundwater contaminant, and 1-naphthol is an important chemical manufacturing intermediate. Directed evolution was used to increase the activity of toluene ortho-monooxygenase (TOM) of Burkholderia cepacia G4 for both chlorinated ethenes and naphthalene oxidation. When expressed in Escherichia coli, the variant TOM-Green degraded TCE (2.5 ± 0.3 versus 1.39 ± 0.05 nmol/min/mg of protein), 1,1-dichloroethylene, and trans-dichloroethylene more rapidly. Whole cells expressing TOM-Green synthesized 1-naphthol at a rate that was six times faster than that mediated by the wild-type enzyme at a concentration of 0.1 mM (0.19 ± 0.03 versus 0.029 ± 0.004 nmol/min/mg of protein), whereas at 5 mM, the mutant enzyme was active (0.07 ± 0.03 nmol/min/mg of protein) in contrast to the wild-type enzyme, which had no detectable activity. The regiospecificity of TOM-Green was unchanged, with greater than 97% 1-naphthol formed. The beneficial mutation of TOM-Green is the substitution of valine to alanine in position 106 of the ?-subunit of the hydroxylase, which appears to act as a smaller “gate” to the diiron active center. This hypothesis was supported by the ability of E. coli expressing TOM-Green to oxidize the three-ring compounds, phenanthrene, fluorene, and anthracene faster than the wild-type enzyme. These results show clearly that random, in vitro protein engineering can be used to improve a large multisubunit protein for multiple functions, including environmental restoration and green chemistry.

Canada, Keith A.; Iwashita, Sachiyo; Shim, Hojae; Wood, Thomas K.

2002-01-01

205

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

206

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...

207

PERFORMANCE OF TRICKLE BED BIOFILTERS UNDER HIGH TOLUENE LOADING  

EPA Science Inventory

The performance of two pelletized media biofilters, highly loaded with toluene, was evaluated in this study. oth biofilters were operated as the same influent concentration of 250 ppmv toluene. iofilter "A" was operated at 1 minute EBRT and biofilter "B" at 0.67 minute EBRT. he i...

208

Behavior of Toluene Added to Sludge-Amended Soils.  

National Technical Information Service (NTIS)

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. ...

Y. Jin G. A. O'Connor

1990-01-01

209

Urinary Hippuric Acid Excretion as an Index of Toluene Exposure  

Microsoft Academic Search

A simple procedure is described for the analysis of hippuric acid in urine. The sample is extracted with an isopropyl alcohol-diethyl ether mixture, and the hippuric acid is measured in the extractant by ultraviolet spectrophotometry. The excretion of hippuric acid in urine as a metabolic product of toluene was studied in relation to its usefulness in industrial exposures to toluene.

Leonard D. Pagnotto; Lionel M. Lieberman

1967-01-01

210

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

211

Biotransformation of nitrobenzene by bacteria containing toluene degradative pathways  

Microsoft Academic Search

Nonpolar nitroaromatic compounds have been considered resistant to attack by oxygenases because of the electron withdrawing properties of the nitro group. The authors have investigate the ability of seven bacterial strains containing toluene degradative pathways to oxidize nitrobenzene. Cultures were induced with toluene vapor prior to incubation with nitrobenzene, and products were identified by high-performance liquid chromatography and gas chromatography-mass

B. E. Haigler; J. C. Spain

1991-01-01

212

Risk of Learning and Behavioral Disorders Following Prenatal and Early Postnatal Exposure to Tetrachloroethylene (PCE)-contaminated Drinking Water  

PubMed Central

This population-based retrospective cohort study examined the association between developmental disorders of learning, attention and behavior and prenatal and early postnatal drinking water exposure to tetrachloroethylene (PCE) on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling software, and a Geographic Information System (GIS). Mothers completed a questionnaire on disorders of attention, learning and behavior in their children and on potential confounding variables. The final cohort consisted of 2,086 children. Results of crude and multivariate analyses showed no association between prenatal exposure and receiving tutoring for reading or math, being placed on an Individual Education Plan, or repeating a school grade (adjusted Odds Ratios (OR)=1.0–1.2). There was also no consistent pattern of increased risk for receiving a diagnosis of Attention Deficit Disorder (ADD) or Hyperactive Disorder (HD), special class placement for academic or behavioral problems, or lower educational attainment. Modest associations were observed for the latter outcomes only in the low exposure group (e.g., adjusted ORs for ADD were 1.4 and 1.0 for low and high exposure, respectively). (All ORs are based on an unexposed referent group.) Results for postnatal exposure through age five years were similar to those for prenatal exposure. We conclude that prenatal and early postnatal PCE exposure is not associated with disorders of attention, learning and behavior identified on the basis of questionnaire responses and at the exposure levels experienced by this population.

Janulewicz, Patricia A; White, Roberta F; Winter, Michael R; Weinberg, Janice M; Gallagher, Lisa E; Vieira, Veronica; Webster, Thomas F; Aschengrau, Ann

2008-01-01

213

Prediction of risk from indoor exposure to tetrachloroethylene; Pharmacokinetic considerations under steady-state and dynamic exposure conditions  

SciTech Connect

Multicompartment models known as physiologically based pharmacokinetic (PB-PK) models are increasingly used in health risk assessment for volatile organic compounds (VOC's). These models predict the uptake, metabolism and excretion of such chemicals in exposed animals or people. In current applications of such models, however, input has consisted of simplistic exposure scenarios that often do not represent realistic environment exposure conditions of regulatory concern. Recent studies have shown that exposure to VOC's in drinking-water supplies can result not only from direct ingestion of contaminated water, but also from inhalation and dermal absorption. McKone has shown that daily personal exposure to VOC's from tap water through inhalation can range from 1.5 to 6.0 times the exposure attributable to ingestion of 2 L/d of water. This daily exposure is dominated by large, short-term exposures during specific activities such as showering or bathing and time spent in bathrooms. In the context of PB-PK models, these observations therefore raise the question: Is the daily metabolized dose sensitive to the time profile of exposure To address this question, the authors here explore how a realistic scenario for indoor respiratory exposure to tetrachloroethylene (PCE) from ground water affects the extent of PCE metabolism, as predicted by a PB-PK model. They focus on the degree to which dynamic, as opposed to steady-state, modeling is actually necessary to predict PCE metabolism and on whether conclusions in this regard are significantly affected by uncertainty in estimates of parameters that govern PCE metabolism in humans.

Bogen, K.T.; McKone, T.E. (Lawrence Livermore National Lab., CA (USA))

1987-01-01

214

Bioactivation of tetrachloroethylene. Role of glutathione S-transferase-catalyzed conjugation versus cytochrome P-450-dependent phospholipid alkylation.  

PubMed

The metabolism of [14C]tetrachloroethylene (Tetra) and its metabolite S-(1,2,2-trichlorovinyl)-L-cysteine (TCVC) was investigated with in vitro systems to substantiate metabolic pathways of Tetra deduced from in vivo experiments. In the presence of NADPH, rat hepatic microsomal fractions metabolized Tetra to soluble metabolites, which were identified as trichloroacetic acid and oxalic acid by gas chromatography/mass spectroscopy and a metabolite largely bound to microsomal macromolecules. The majority of the alkylated macromolecules were identified as N-trichloroacetylated phospholipids by high performance liquid chromatography and GC/MS. When Tetra was incubated with hepatic microsomes and cytosol in the presence of 10 mM glutathione, but in the absence of NADPH, the formation of a polar metabolite other than trichloroacetic acid and oxalic acid was observed. This metabolite was identified, after hydrolysis to the corresponding cysteine conjugate, as S-(1,2,2-trichlorovinyl)-glutathione (TCVG). Microsomal GSH S-transferases catalyzed TCVG formation more efficiently than cytosolic GSH S-transferases; the competitive substrate 1-chloro-2,4-dinitrobenzene inhibited TCVG formation. In the presence of both NADPH and GSH, TCVG formation in microsomes was decreased, indicating that oxidative metabolism and GSH conjugation of Tetra are competitive reactions. The Tetra metabolite TCVC was cleaved by bacterial cysteine conjugate b-lyase to dichloroacetic acid and pyruvate. The obtained results substantiate the postulated pathways of Tetra biotransformation and demonstrate that both oxidative and conjugative reactions occur in hepatic Tetra metabolism. Phospholipid alkylation, which occurs during oxidative metabolism, may be a deactivation reaction, whereas TCVG formation, renal metabolism to TCVC, and cleavage of TCVC by b-lyase under formation of mutagenic intermediates may contribute to the nephrocarcinogenic effect of Tetra. PMID:2891489

Dekant, W; Martens, G; Vamvakas, S; Metzler, M; Henschler, D

1987-01-01

215

Risk of learning and behavioral disorders following prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water.  

PubMed

This population-based retrospective cohort study examined the association between developmental disorders of learning, attention and behavior and prenatal and early postnatal drinking water exposure to tetrachloroethylene (PCE) on Cape Cod, Massachusetts. Subjects were identified through birth records from 1969 through 1983. Exposure was modeled using information from town water departments, a PCE leaching and transport algorithm, EPANet water flow modeling software, and a Geographic Information System (GIS). Mothers completed a questionnaire on disorders of attention, learning and behavior in their children and on potential confounding variables. The final cohort consisted of 2086 children. Results of crude and multivariate analyses showed no association between prenatal exposure and receiving tutoring for reading or math, being placed on an Individual Education Plan, or repeating a school grade (adjusted Odds Ratios (OR)=1.0-1.2). There was also no consistent pattern of increased risk for receiving a diagnosis of Attention Deficit Disorder (ADD) or Hyperactive Disorder (HD), special class placement for academic or behavioral problems, or lower educational attainment. Modest associations were observed for the latter outcomes only in the low exposure group (e.g., adjusted ORs for ADD were 1.4 and 1.0 for low and high exposure, respectively). (All ORs are based on an unexposed referent group.) Results for postnatal exposure through age five years were similar to those for prenatal exposure. We conclude that prenatal and early postnatal PCE exposure is not associated with disorders of attention, learning and behavior identified on the basis of questionnaire responses and at the exposure levels experienced by this population. PMID:18353612

Janulewicz, Patricia A; White, Roberta F; Winter, Michael R; Weinberg, Janice M; Gallagher, Lisa E; Vieira, Veronica; Webster, Thomas F; Aschengrau, Ann

2008-01-01

216

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

217

Gas sensing properties and in situ diffuse reflectance infrared Fourier transform spectroscopy study of trichloroethylene adsorption and reactions on SnO2 films  

NASA Astrophysics Data System (ADS)

The detection of trichloroethylene has attracted much attention because it has an important effect on human health. The sensitivity of the SnO2 flat-type coplanar gas sensor arrays to 100 ppm trichloroethylene in air was investigated. The adsorption and surface reactions of trichloroethylene were investigated at 100-200 °C by in-situ diffuse reflection Fourier transform infrared spectroscopy (DIRFTS) on SnO2 films. Molecularly adsorbed trichloroethylene, dichloroacetyl chloride (DCAC), phosgene, HCl, CO, H2O, CHCl3, Cl2 and CO2 surface species are formed during trichloroethylene adsorption at 100-200 °C. A possible mechanism of the reaction process is discussed.

Zhang, Zhenxin; Huang, Kaijin; Yuan, Fangli; Xie, Changsheng

2014-05-01

218

Toluene inducing acute respiratory failure in a spray paint sniffer  

PubMed Central

Summary Background: Toluene, formerly known as toluol, is an aromatic hydrocarbon that is widely used as an industrial feedstock and as a solvent. Like other solvents, toluene is sometimes also used as an inhalant drug for its intoxicating properties. It has potential to cause multiple effects in the body including death. Case Report: I report a case of a 27-year-old male, chronic spray paint sniffer, who presented with severe generalized muscle weakness and developed acute respiratory failure requiring ventilatory support. Toluene toxicity was confirmed with measurement of hippuric acid of 8.0 g/L (normal <5.0 g/L). Conclusions: Acute respiratory failure is a rare complication of chronic toluene exposure that may be lethal if it is not recognized immediately. To our knowledge, this is the second case of acute respiratory failure due to toluene exposure.

Peralta, Diego P.; Chang, Aymara Y.

2012-01-01

219

Human Health Effects of Trichloroethylene: Key Findings and Scientific Issues  

PubMed Central

Background: In support of the Integrated Risk Information System (IRIS), the U.S. Environmental Protection Agency (EPA) completed a toxicological review of trichloroethylene (TCE) in September 2011, which was the result of an effort spanning > 20 years. Objectives: We summarized the key findings and scientific issues regarding the human health effects of TCE in the U.S. EPA’s toxicological review. Methods: In this assessment we synthesized and characterized thousands of epidemiologic, experimental animal, and mechanistic studies, and addressed several key scientific issues through modeling of TCE toxicokinetics, meta-analyses of epidemiologic studies, and analyses of mechanistic data. Discussion: Toxicokinetic modeling aided in characterizing the toxicological role of the complex metabolism and multiple metabolites of TCE. Meta-analyses of the epidemiologic data strongly supported the conclusions that TCE causes kidney cancer in humans and that TCE may also cause liver cancer and non-Hodgkin lymphoma. Mechanistic analyses support a key role for mutagenicity in TCE-induced kidney carcinogenicity. Recent evidence from studies in both humans and experimental animals point to the involvement of TCE exposure in autoimmune disease and hypersensitivity. Recent avian and in vitro mechanistic studies provided biological plausibility that TCE plays a role in developmental cardiac toxicity, the subject of substantial debate due to mixed results from epidemiologic and rodent studies. Conclusions: TCE is carcinogenic to humans by all routes of exposure and poses a potential human health hazard for noncancer toxicity to the central nervous system, kidney, liver, immune system, male reproductive system, and the developing embryo/fetus.

Jinot, Jennifer; Scott, Cheryl Siegel; Makris, Susan L.; Cooper, Glinda S.; Dzubow, Rebecca C.; Bale, Ambuja S.; Evans, Marina V.; Guyton, Kathryn Z.; Keshava, Nagalakshmi; Lipscomb, John C.; Barone, Stanley; Fox, John F.; Gwinn, Maureen R.; Schaum, John; Caldwell, Jane C.

2012-01-01

220

Bioremediation of trichloroethylene contaminated groundwater using anaerobic process.  

PubMed

Anaerobic remediation of trichloroethylene (TCE) contaminated soil and groundwater was studied in laboratory setups. In this process fermentation of polymeric organic materials (POMS) produced volatile fatty acids (VFAs) that were electron donors in reductive dechlorination of TCE. Shredded peanut shell was selected as low cost POM and the experiments were set up in 500 ml Erlenmeyer flasks. In the setups, approximately 25 mg of leachate contaminated soil was used as the main source of microorganisms and about 5 g of shredded peanut shell (0.5-2.36 mm) was added to produce VFAs for dechlorination of TCE. In the first set of experiments, fermentation of soil and shredded peanut shell was studied and it was found that VFAs were produced continuously with increasing concentration (5.63 mM as CH3COOH from the first day to 17.17 in the 10th day of the experiment). During the fermentation, concentration of ammonia-nitrogen was 22-50 mg/L, the ratio of VFA to NH3 was 15.29-23.44 and pH was 5.24-6.00. These results show that the system was appropriate for microorganism activities. In the second set of experiments, TCE (approximately 48 mg/L) was added to the fermentation system and remediation of TCE by reductive dechlorination was studied. It was found that 0.04(+/-0.01) mg TCE adsorbed to a gram of soil and peanut shells at the beginning of the experiment and based on mass balance of the system, TCE concentration in water was linearly reduced at the rate of 0.0098 mg/hr. PMID:19092188

Chomsurin, Cheema; Kajorntraidej, Juthathip; Luangmuang, Kongrit

2008-01-01

221

Physiologically based pharmacokinetic models for trichloroethylene and its oxidative metabolites.  

PubMed Central

Trichloroethylene (TCE) pharmacokinetics have been studied in experimental animals and humans for over 30 years. Compartmental and physiologically based pharmacokinetic (PBPK) models have been developed for the uptake, distribution, and metabolism of TCE and the production, distribution, metabolism, and elimination of P450-mediated metabolites of TCE. TCE is readily taken up into systemic circulation by oral and inhalation routes of exposure and is rapidly metabolized by the hepatic P450 system and to a much lesser degree, by direct conjugation with glutathione. Recent PBPK models for TCE and its metabolites have focused on the major metabolic pathway for metabolism of TCE (P450-mediated metabolic pathway). This article briefly reviews selected published compartmental and PBPK models for TCE. Trichloroacetic acid (TCA) is considered a principle metabolite responsible for TCE-induced liver cancer in mice. Liver cancer in mice was considered a critical effect by the U.S. Environmental Protection Agency for deriving the current maximum contaminant level for TCE in water. In the literature both whole blood and plasma measurements of TCA are reported in mice and humans. To reduce confusion about disparately measured and model-predicted levels of TCA in plasma and whole blood, model-predicted outcomes are compared for first-generation (plasma) and second-generation (whole blood) PBPK models published by Fisher and colleagues. Qualitatively, animals and humans metabolize TCE in a similar fashion, producing the same metabolites. Quantitatively, PBPK models for TCE and its metabolites are important tools for providing dosimetry comparisons between experimental animals and humans. TCE PBPK models can be used today to aid in crafting scientifically sound public health decisions for TCE.

Fisher, J W

2000-01-01

222

Trichloroethylene transformation by methanotrophs from a groundwater aquifer  

SciTech Connect

This research focuses on trichloroethylene (TCE) transformation by mixed and pure methanotrophic cultures that were enriched and isolated from groundwater and soils from an aquifer. Two of the mixed cultures obtained by enrichment on methane, mixed cultures MM1 and MM3, contained type 2 methanotrophs. A pure culture possessing type 1 intracytoplasmic membranes and expressing only membrane-associated methane monooxygenase was isolated from mixed culture MM2 and ascribed to the genus Methylomonas. A type 2 isolate, CSC-1, was obtained from mixed culture MM1. TCE was biologically transformed and mineralized to carbon dioxide. In the mixed cultures the TCE was almost completely degraded, whereas in Methylomonas sp, strain MM2, most of the TCE-carbon remained in aqueous intermediates. The TCE transformation rates were variable, depending upon growth conditions and conditions applied during the TCE transformation assays. The formulation of the growth medium, including the presence or absence of copper and EDTA, significantly influenced TCE transformation rates. TCE oxidation occurred in the presence, as well as the absence of methane. Methane competitively inhibited TCE oxidation by Methylomonas sp. strain MM2. Carbon monoxide, produced during TCE transformation by Methylomonas sp. strain MM2, was oxidized as well and also competitively inhibited TCE oxidation. High oxygen concentrations were inhibitory to TCE transformation. During starvation TCE transformation capability was lost and the rate of decline followed exponential decay. Formate amendment increased TCE and carbon monoxide oxidation rates by Methylomonas sp. strain MM2 but did not affect TCE transformation rates by mixed culture MM1 or isolate CSC-1.

Henry, S.M.

1991-01-01

223

Preliminary response of a pristine aquifer when facing toluene contamination  

NASA Astrophysics Data System (ADS)

Toluene is a common groundwater contaminant due to the wide spread of gasoline and industrial solvents. The understanding of how and when ecosystems initially respond to the presence of toluene is yet limited, because field investigations rarely start before a contamination has occurred. In order to investigate for the first time such a scenario, a pristine indoor aquifer model (0.8 - 0.7 - 5 m) was constructed, filled with natural sediment, flushed with natural groundwater at a rate of 9 L/hr, and subsequently exposed to a toluene contamination. Investigation was done to the chemical and biological parameters of the model, including oxygen concentration (9.6 mg/L), nitrate concentration (5.8 mg/L), small organic carbon content (0.8 mg/L), microbial abundance (4 x 104 cell/mL), and ATP (0.01 nM). This agreed with the condition of a typical pristine and oligotrophic aquifer. A 30-hr aqueous toluene pulse (water saturated with toluene) was injected into the system together with a conservative tracer (90% D2O). Water samples were collected 4.2 m away from the injection source. The comparison between the toluene and D2O breakthrough curves indicated that a portion of toluene was removed by degradation at a pseudo 1st order rate of 0.017/hr. Stable carbon isotope values of toluene were also measured along with the breakthrough curves. ?13C values were more positive than the original input, confirming that biodegradation had taken place. Subsequent to the pulse, a constant injection of aqueous toluene together with bromide was applied to obtain a deeper insight of the biological and geochemical processes in the aquifer. High resolution water sampling over the entire aquifer model was conducted 80 hrs after the start of constant injection. Microbial abundance and living biomass (ATP) were observed to be 10 - and 100 -, respectively, higher than under pristine conditions. Biodegradation was detected by comparing the concentration of toluene and bromide, and was confirmed by a significant depletion of oxygen concentrations in the center of the plume. Subsequent sediment sampling revealed a pronounced decrease in bacterial diversity and evenness in the toluene plume, indicating fast establishment of the degraders and disappearance of sensitive members. Changes of microbial community composition were accompanied by a build up of biomass and high bacterial carbon production rates. Our study shows that microbial degradation of toluene occurs immediately (within 50 hrs) after exposure of the pristine aquifer to the contaminant. Changes in biological and geochemical processes give additional evidences that the system responds very fast towards toluene contamination and has a high potential for natural attenuation.

Qiu, S.; Herzyk, A.; Maloszewski, P.; Larentis, M.; Griebler, C.; Elsner, M.

2012-04-01

224

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

225

Detailed mechanism of toluene oxidation and comparison with benzene  

NASA Technical Reports Server (NTRS)

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 wide range of initial temperatures and pressures. Attempts to compute experimentally measured concentration profiles for toluene oxidation in a turbulent reactor were partially successful. An extensive sensitivity analysis was performed to determine the reactions which control the ignition process and the rates of formation and destruction of various species. The most important step was found to be the reaction of toluene with molecular oxygen, followed by the reactions of hydroperoxyl and atomic oxygen with benzyl radicals. These findings contrast with the benzene oxidation, where the benzene-molecular oxygen reaction is quite unimportant and the reaction of phenyl with molecular oxygen dominates. In the toluene mechanism the corresponding reaction of benzyl radicals with oxygen is unimportant. Two reactions which are important in the oxidation of benzene also influence the oxidation of toluene for several conditions. These are the oxidations of phenyl and cyclopentadienyl radicals by molecular oxygen. The mechanism presented successfully computes the decrease of toluene concentration with time in the nitrogen diluted turbulent reactor. This fact, in addition to the good prediction of ignition delay times, shows that this mechanism can be used for modeling the ignition and combustion process in practical, well-mixed combustion systems.

Bittker, David A.

1988-01-01

226

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

227

TRICHLOROETHYLENE SORPTION AND OXIDATION USING A DUAL FUNCTION SORBENT/CATALYST IN A FALLING FURNACE REACTOR  

EPA Science Inventory

A dual function medium (Cr-ZSM-5), capable of physisorbing trichloroethylene (TCE) at ambient temperature and catalytically oxidizing it at elevated temperature (-350 degrees C) was utilized in a novel continuous falling furnace reactor system to store and periodically destroy t...

228

CATALYTIC STEAM REFORMING OF CHLOROCARBONS: TRICHLOROETHANE, TRICHLOROETHYLENE AND PERCHLOROETHYLENE. (R826694C633)  

EPA Science Inventory

The effective destruction of trichloroethane, trichloroethylene and perchloroethylene by steam reforming with a commercial nickel catalyst has been demonstrated. Conversion levels of up to 0.99999 were attained in both laboratory and semi-pilot experiments, with the products c...

229

The Implication of Iron Oxide Nanoparticles on the Removal of Trichloroethylene by Adsorption  

EPA Science Inventory

The fate and transport of Fe2O3 NPs in a granular activated carbon (GAC) adsorber and its impact on the removal of trichloroethylene (TCE) by GAC was investigated. The hydrodynamic diameter of Fe2O3 NPs was measured with time to evaluat...

230

Remediation of trichloroethylene and monochlorobenzene contaminated groundwater by Iron and activated carbon  

Microsoft Academic Search

Batch tests were conducted to investigate the performance of various material remediation systems for the degradation and sorption of aqueous-phase trichloroethylene (TCE) and monochlorobenzene (MCB). The objective of this study was to evaluate the effects of zero-valent iron (ZVI) and granular activated carbon (GAC) as useful materials to build permeable reactive barriers (PRBs). ZVI is conventionally used as PRB material

L. Jeon; S. Jeen; D. Koh; H. Chang

2006-01-01

231

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

232

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

Microsoft Academic Search

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

R. Varma; S. P. Nandi

1991-01-01

233

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...

234

COST-EFFECTIVENESS OF REMEDIATION OF TRICHLOROETHYLENE IN GROUNDWATER (SYSTEMS ANALYSIS BRANCH, SUSTAINABLE TECHNOLOGY DIVISION, NRMRL)  

EPA Science Inventory

The purpose of this project was to compare the cost and performance of technologies used for the remediation of dissolved trichloroethylene plumes. Data for the conventional treatment technology (pump and treat) as well as innovative/emerging technologies, e.g., surfactant inject...

235

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...

236

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...

237

CARCINOGENICITY OF TRICHLOROETHYLENE AND ITS METABOLITES, TRICHLOROACETIC ACID AND DICHLOROACETIC ACID, IN MOUSE LIVER  

EPA Science Inventory

Trichloroethylene (TCE) has previously been shown to be carcinogenic in mouse liver when given by daily gavage in corn oil. The metabolism of TCE results, in part, in the formation of trichloroacetic acid (TCA) as a major metabolite and dichloroacetic acid (DCA) as a minor metabo...

238

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...

239

Mechanisms Involved in Trichloroethylene Induced Liver Cancer: Importance to Environmental Cleanup.  

National Technical Information Service (NTIS)

Trichloroethylene (TCE) is a common contaminant of groundwater as a result of poor disposal practices of the past. As a consequence, this solvent is the focus of many clean-up operations of hazardous waste sites. The finding that TCE induces liver cancer ...

2004-01-01

240

Mechanism involved in trichloroethylene-induced liver cancer: Importance to environmental cleanup. 1998 annual progress report.  

National Technical Information Service (NTIS)

The objective of this project is to develop critical data for changing risk-based clean-up standards for trichloroethylene (TCE). The project is organized around two interrelated tasks: Task 1 addresses the tumorigenic and dosimetry issues for the metabol...

R. J. Bull J. H. Miller L. B. Sasser I. R. Schultz B. D. Thrall

1998-01-01

241

CYTOCHROME P450-DEPENDENT METABOLISM OF TRICHLOROETHYLENE IN THE RAT KIDNEY  

EPA Science Inventory

The metabolism of trichloroethylene (Tri) by cytochrome P450 (P450) was studied in microsomes from liver and kidney homogenates and from isolated renal proximal tubular (PT) and distal tubular (DT) cells from male Fischer 344 rats. Chloral hydrate (CH) was the only metabolite con...

242

Contribution of Dichloroacetate and Trichloroacetate to Liver Tumor Induction in Mice by Trichloroethylene  

Microsoft Academic Search

Determining the key events in the induction of liver cancer in mice by trichloroethylene (TRI) is important in the determination of how risks from this chemical should be treated at low doses. At least two metabolites can contribute to liver cancer in mice, dichloroacetate (DCA) and trichloroacetate (TCA). TCA is produced from metabolism of TRI at systemic concentrations that can

Richard J. Bull; Gayle A. Orner; Rita S. Cheng; Lisa C. Stillwell; Anja J. Stauber; Lyle B. Sasser; Melissa K. Lingohr; Brian D. Thrall

2002-01-01

243

78 FR 34377 - Trichloroethylene TSCA Chemical Risk Assessment; Notice of Public Meetings and Opportunity to...  

Federal Register 2010, 2011, 2012, 2013

...TSCA Workplan Chemical Risk Assessment for Trichloroethylene: Degreaser...unless you provide it in the body of your comment. If you send...contact information in the body of your comment and with any...Stan Barone, Jr., Risk Assessment Division (7403M),...

2013-06-07

244

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...

245

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...

246

Observations on the Concentrations of Trichloroethylene in Blood and Expired Air Following Exposure of Humans  

Microsoft Academic Search

Humans were exposed to approximately 200 ppm of trichloroethylene (TCE) in air. Pre- and post-exposure clinical findings were noted as well as subjective and physiological responses during exposures. TCE was detected in the blood in one-half hour and reached a maximum in two hours. TCE was detectable in the expired air for more than five hours after the exposures. Measurement

R. D. Stewart; H. H. Gay; D. S. Erley; C. L. Hake; J. E. Peterson

1962-01-01

247

Use of a Micellar-Rich Coacervate Phase to Extract Trichloroethylene from Water  

Microsoft Academic Search

At temperatures above the “cloud point,” aqueous nonionic surfactant micellar solutions can separate into two phases: a micellar-rich coacervate phase and a dilute phase. Because the coacervate phase is a concentrated micellar solution, organic solute tends to concentrate in the coacervate as a result of solubilization. In this study up to 91% of trichloroethylene (TCE) was extracted into the coacervate

WAROPHAT KIMCHUWANIT; SOMCHAI OSUWAN; JOHN F. SCAMEHORN; JEFFREY H. HARWELL; KENNETH J. HALLER

2000-01-01

248

Health effects of environmental contaminant exposure: an intrafile comparison of the Trichloroethylene Subregistry.  

PubMed

The establishment of the National Exposure Registry represents the first major effort toward longitudinal surveillance of general populations exposed long-term to low levels of specific substances in the environment. The authors investigated the National Exposure Registry's Trichloroethylene Subregistry intrasubregistry differences with respect to health outcomes and the possible relationships with types and levels of chemical exposure. Investigators divided the 4041 living members of the Trichloroethylene Subregistry into 4 subgroups, by type(s) of exposures (chemicals) and duration and level of exposures. The authors compared the reporting rates for 25 health outcomes across subgroups. The authors used logistic regression, in which age, sex, education, smoking history, and occupational history were the covariates. Statistically significant increases in reporting rates were seen with (a) increased maximum trichloroethylene exposures for the outcome stroke, (b) increased cumulative chemical exposure for respiratory allergies, and (c) duration of exposure for hearing impairment. Consistently elevated reporting rates across the exposure subgroups were seen for hearing impairment, speech impairment, asthma and emphysema, respiratory allergies, and stroke. Reporting rates for urinary tract disorders were related only to cumulative chemical levels. The authors noted that there appeared to be a relationship between trichloroethylene and reporting rates for speech impairment, hearing impairment, and stroke and between volatile organic compounds and asthma and emphysema, respiratory allergies, and urinary tract disorders. PMID:10433181

Burg, J R; Gist, G L

1999-01-01

249

Monitoring remediation of trichloroethylene using a chemical fiber optic sensor: Field studies  

Microsoft Academic Search

Field tests of a remote fiber optic chemical sensor have recently been completed. The sensor has measured trace quantities of organohalides in the vadose zone and groundwater. Due to its toxicological importance and accessibility, a specific contaminant monitored was trichloroethylene (TCE). Two elements considered in these field measurements included temperature and carbon dioxide (CO[sub 2]) fluctuations. The effects of these

B. Jr. Colston; S. B. Brown; K. Langry; P. Daley; F. P. Milanovich

1992-01-01

250

Monitoring remediation of trichloroethylene using a chemical fiber optic sensor: Field studies  

Microsoft Academic Search

Field tests of a remote fiber optic chemical sensor have recently been completed. The sensor has measured trace quantities of organohalides in the vadose zone and groundwater. Due to its toxicological importance and accessibility, a specific contaminant monitored was trichloroethylene (TCE). Two elements considered in these field measurements included temperature and carbon dioxide (COâ) fluctuations. The effects of these properties

B. Jr. Colston; S. B. Brown; K. Langry; P. Daley; F. P. Milanovich

1992-01-01

251

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

252

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...

253

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...

254

Spermatid Micronucleus Analyses of Trichloroethylene and Chloral Hydrate Effects in Mice.  

National Technical Information Service (NTIS)

Mice were exposed by inhalation to trichloroethylene (TCE) or by i.p. injection to the TCE metabolite, chloral hydrate (CH). Early spermatids were analyzed for micronucleus (MN) frequency and the presence or absence of kinetochore(s) using fluorochrome-la...

J. W. Allen B. W. Collins P. A. Evansky

1994-01-01

255

Swelling of cross-linked polystyrene spheres in toluene vapor  

SciTech Connect

The swelling behavior of individual micron-sized polystyrene (PS) spheres in toluene vapor was studied via mass loading by means of micromechanical cantilever sensors. For 4%-8% cross-linked PS a mass increase of 180% in saturated toluene vapor was measured. The mass of the swollen PS sphere decreases with increasing exposure time to ultraviolet light. In addition, the swelling response is significantly different between the first and the second exposure to toluene vapor. This is attributed to the formation of a cross-linked shell at the surface of the PS spheres. Shape persistent parts were observed for locally irradiated PS spheres.

Zhang, R.; Graf, K.; Berger, R. [Polymer Physics Group, Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany); Polymer Physics Group, Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany and Research Center for Micro- and Nanochemistry and Engineering, University of Siegen, D-57068 Siegen (Germany); Polymer Physics Group, Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany)

2006-11-27

256

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

SciTech Connect

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 investigated for determining the number and placement of monitoring wells during a remedial investigation for trichloroethylene. The results of this study should also give some insight into what emphasis should be placed on the nine National Contingency Plan criteria.

Butterfield, G.A.

1991-09-01

257

Urinary hippuric acid concentration after occupational exposure to toluene.  

PubMed Central

The results of industrial investigations have shown a correlation between the rate of hippuric acid excretion in a single urine sample collected after daily occupational exposure and the amount of toluene absorbed. The rate of hippuric acid excretion and the average concentration of toluene vapour during exposure time were also related. The quantitative range of the test has been limited to amounts exceeding 425 mg of toluene and concentrations exceeding 69 ppm of toluene in the air because of the physiological presence of hippuric acid in urine. The rate of hippuric acid excretion in urine depends on diuresis and is constant for urinary fractions with diuresis of 30 ml/h. The physiological excretion rate was 20 mg/h with a standard deviation +/- 4.3 mg/h, maximal physiological level 33 mg/h.

Wilczok, T; Bieniek, G

1978-01-01

258

Atmospheric analyzer, carbon monoxide monitor and toluene diisocyanate monitor  

NASA Technical Reports Server (NTRS)

The purpose of the atmospheric analyzer and the carbon monoxide and toluene diisocyanate monitors is to analyze the atmospheric volatiles and to monitor carbon monoxide and toluene diisocyanate levels in the cabin atmosphere of Skylab. The carbon monoxide monitor was used on Skylab 2, 3, and 4 to detect any carbon monoxide levels above 25 ppm. Air samples were taken once each week. The toluene diisocyanate monitor was used only on Skylab 2. The loss of a micrometeoroid shield following the launch of Skylab 1 resulted in overheating of the interior walls of the Orbital Workshop. A potential hazard existed from outgassing of an isocyanate derivative resulting from heat-decomposition of the rigid polyurethane wall insulation. The toluene diisocyanate monitor was used to detect any polymer decomposition. The atmospheric analyzer was used on Skylab 4 because of a suspected leak in the Skylab cabin. An air sample was taken at the beginning, middle, and the end of the mission.

Shannon, A. V.

1977-01-01

259

Conducting Polymer Electrochemically Generated Via Anodic Oxidation of Toluene.  

National Technical Information Service (NTIS)

As opposed to the much harsher conditions demanded in homogeneous solutions, a conducting polymer of toluene is readily formed by anodic oxidation of acetonitrile solutions containing the precursor. The fabrication of new conductive polymers is of interes...

D. B. Parry J. M. Harris K. Ashley S. Pons

1988-01-01

260

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

261

Predicting toluene degradation in organic Rankine-cycle engines  

SciTech Connect

This paper describes the measurement of toluene degradation in dynamic loop tests that simulate operation of an organic Rankine-cycle engine. Major degradation products and degradation mechanisms are identified, and degradation is quantified. Results indicate that toluene is a stable fluid with benign degradation products, provided that oxygen is excluded from the engine. A means of predicting degradation in the engine is developed. 3 refs., 4 figs., 5 tabs.

Cole, R.L.; Demirgian, J.C.; Allen, J.W.

1987-01-01

262

Toluene abuse and white matter: a model of toxic leukoencephalopathy.  

PubMed

The brain is the primary target of toluene (methylbenzene), the major solvent in spray paint and a constituent of many other easily obtained commercial and industrial products. The effects of acute intoxication can be dramatic and the lasting adverse effects of inhalants may be highly injurious. Mental status alterations range from acute confusional state to coma. Toluene abuse effects on white matter are demonstrable neuroradiologically and neuropathologically, and have important neurobehavioral consequences. PMID:23688693

Filley, Christopher M

2013-06-01

263

Anoxic hypolimnion is a significant source of biogenic toluene  

Microsoft Academic Search

Toluene is the predominant aromatic compound in freshwater lakes in Central Europe1-3 and sea water4-6. Its concentrations exceed those of the xylene and ethyltoluene isomers both of which also occur in a comparable concentration range. Toluene is also the most important aromatic compound in the air of Europe7, North America8 and Australia9. Anthropogenic sources are held to be responsible for

F. Jüttner; J. J. Henatsch

1986-01-01

264

AN EXAMPLE OF MODEL STRUCTURE DIFFERENCES USING SENSITIVITY ANALYSES IN PHYSIOLOGICALLY BASED PHARMACOKINETIC MODELS OF TRICHLOROETHYLENE IN HUMANS  

EPA Science Inventory

Abstract 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 metabo...

265

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...

266

COUNTER-DIFFUSION OF ISOTOPICALLY LABELED TRICHLOROETHYLENE IN SILICA GEL AND GEOSORBENT MICROPORES: COLUMN RESULTS. (R822626)  

EPA Science Inventory

To investigate counter-diffusion in microporous sorbents, the rate of exchange between deuterated trichloroethylene (DTCE) in fast desorbing sites and nondeuterated TCE (1HTCE) in slow desorbing sites was measured. Exchange rates were measured for a sili...

267

Analysis of the Potential for Plant Uptake of Trichloroethylene and an Assessment of the Relative Risk from Different Crop Types.  

National Technical Information Service (NTIS)

This research expands our limited knowledge on the influence of plants on the fate and effects of trichloroethylene (TCE), providing a screening tool on which to base decisions regarding the need for actual sampling of plants. First, physicochemical prope...

R. A. C. Agustin

1994-01-01

268

Development of a Physiologically-Based Pharmacokinetic Model of Trichloroethylene and Its Metabolites for Use in Risk Assessment.  

National Technical Information Service (NTIS)

A physiologically based pharmacokinetics (PBPK) model was developed which provides a comprehensive description of the kinetics of trichloroethylene (TCE) and its metabolites, trichloroethanol (TCOH). and trichloroacetic acid (TCA), in the mouse, rat, and ...

T. R. Covington H. J. Clewell J. W. Fisher

2004-01-01

269

Toluene diffusion and reaction in unsaturated Pseudomonas putida biofilms  

SciTech Connect

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, the authors 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. They experimentally determined diffusion and kinetic parameters for Pseudomonas putida biofilms, then predicted biodegradation rates over a range of matric water potentials. For validation, the authors 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 {times} 10{sup {minus}7} cm{sup 2}/s, which is approximately two orders of magnitude lower than toluene diffusivity in water. Their 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, P.A.; Hunt, J.R.; Firestone, M.K. [Univ. of California, Berkeley, CA (United States)] [Univ. of California, Berkeley, CA (United States)

1997-12-20

270

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

271

Adsorption of toluene on carbon nanofibers prepared by electrospinning.  

PubMed

This paper reports the novel results of activated carbon nanofibers (ACNF) used to improve the toluene adsorption capacity. The ACNF was prepared by stabilization, carbonization and activation after electrospinning the polymer solution of polyacrylonitrile (PAN) in N, N-dimethylformamide. The average diameter of the ACNF was approximately 300 nm, ranging from 200 to 500 nm. The toluene adsorption capacity of ACNF10 activated at 1000 degrees C increased to 65 g-toluene/100 g-ACNF. This was attributed to the high specific surface area (1403 m(2)/g), large micropore volume (0.505 cm(3)/g), and narrow average pore diameter (6.0 A). The oxygen to carbon ratio (O/C ratio) in ACNF10 was 1.8%. This O/C ratio appears to induce a higher toluene adsorption capacity, which originates from a non-polar interaction between the ACNF surface and toluene. In conclusion, the electrospun ACNF prepared in this study promotes the adsorption of toluene through the high specific surface area, large pore volume, narrow pore diameter and low O/C ratio. PMID:18262599

Oh, Gil-Young; Ju, Young-Wan; Kim, Mi-Young; Jung, Hong-Ryun; Kim, Hyung Jin; Lee, Wan-Jin

2008-04-15

272

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

273

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

274

Health assessment for Hill Air Force Base, Ogden, Utah, Region 8. CERCLIS No. UT0571724350. Preliminary report  

SciTech Connect

Hill Air Force Base (AFB) is located approximately 25 miles north of Salt Lake City and five miles south of Ogden, Utah. A installation Restoration Program has identified several areas of environmental contamination. Contaminants of concern include: lead, chromium, manganese, trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, 1,2-dichlorobenzene, vinyl chloride, 1,2-dichloroethane, chlorobenzene, nitrate, toluene, and methylene chloride. The site is considered to be of public health concern because of the risk to human health caused by the likelihood of exposure to hazardous substances via ingestion, inhalation, and direct dermal contact with contamination in the ground water and soil.

Not Available

1989-01-27

275

Improvement of HS-SPME for analysis of volatile organic compounds (VOC) in water samples by simultaneous direct fiber cooling and freezing of analyte solution  

Microsoft Academic Search

The sensitivity and precision of headspace solid-phase micro extraction (HS-SPME) at an analyte solution temperature (T\\u000a as) of +35 C and a fiber temperature (T\\u000a fiber) of +5 C were compared with those for HS-SPME at T\\u000a as and T\\u000a fiber of ?20 C for analysis of the volatile organic compounds benzene, 1,1,1-trichloroethane, trichloroethylene, toluene, o-xylene, ethylbenzene, m\\/p-xylene, and tetrachloroethylene in water samples.

Elke Fries; Wilhelm Püttmann

2006-01-01

276

Evaluation of simultaneous biodegradation of methane and toluene in landfill covers.  

PubMed

The biodegradation of CH4 and toluene in landfill cover soil (LCS) and waste biocover soil (WBS) was investigated with a serial toluene concentration in the headspace of landfill cover microcosms in this study. Compared with the LCS sample, the higher CH4 oxidation activity and toluene-degrading capacity occurred in the WBS sample. The co-existence of toluene in landfill gas would positively or negatively affect CH4 oxidation, mainly depending on the toluene concentrations and exposure time. The nearly complete inhibition of toluene on CH4 oxidation was observed in the WBS sample at the toluene concentration of ?80,000mgm(-3), which was about 10 times higher than that in the LCS sample. The toluene degradation rates in both landfill covers fitted well with the Michaelis-Menten model. These findings showed that WBS was a good alternative landfill cover material to simultaneously mitigate emissions of CH4 and toluene from landfills to the atmosphere. PMID:24801894

Su, Yao; Zhang, Xuan; Wei, Xiao-Meng; Kong, Jiao-Yan; Xia, Fang-Fang; Li, Wei; He, Ruo

2014-06-15

277

Distribution and movement of trichloroethylene in ground water in the Tucson area, Arizona  

USGS Publications Warehouse

In 1981, investigations of groundwater quality around Tucson International Airport revealed a number of wells that pumped water contaminated with trichloroethylene. Subsequent investigations resulted in the delineation of three distinct areas of contamination, the largest of which encompasses about 5 sq mi of aquifer surface area. Most of the contamination is in the top 100 ft of the saturated groundwater flow system. A fine-grained confining layer that is present in much of the contaminated area significantly limits the vertical movement of the chlorinated groundwater. Within the contaminated area, measured trichloroethylene concentrations were as high as 3,100 mg/L in 1984. Measured concentrations are highly variable vertically as well as horizontally. Future quantitative studies of contaminant movement may benefit from additional data collection and experiments to determine which contaminant transport and groundwater flow equations are most appropriate. (Author 's abstract)

Leake, S. A.; Hanson, R. T.

1987-01-01

278

Kinetic modeling study of toluene pyrolysis at low pressure  

SciTech Connect

A detailed kinetic model, consisting of 137 species and 530 reactions, was developed to simulate toluene pyrolysis at low pressure within the temperature range from 1270 to 1870 K. The mole fraction profiles predicted for pyrolysis species up to phenanthrene were in good agreement with the experiment. The decomposition pathways of toluene and the growth pathways to polycyclic aromatic hydrocarbons (PAHs) were discussed from reaction flux analysis. Toluene decomposes through the reaction sequence C{sub 6}H{sub 5}CH{sub 3}{yields} C{sub 6}H{sub 5}CH{sub 2}{yields}C{sub 7}H{sub 6}{yields}c-C{sub 5}H{sub 5}{yields}C{sub 3}H{sub 3}, which also has a predominant contribution to the production of acetylene. Furthermore, sensitivity analysis showed that the primary decomposition reactions of toluene, C{sub 6}H{sub 5}CH{sub 3}=C{sub 6}H{sub 5}CH{sub 2}+H and C{sub 6}H{sub 5}CH{sub 3}=C{sub 6}H{sub 5}+CH{sub 3}, have great influences on the formation of small molecules, such as phenyl radical, benzyl radical, C2- and C3-species, which are critical to the formation of PAHs in the pyrolysis of toluene. (author)

Zhang, Lidong; Cai, Jianghuai; Zhang, Taichang [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui (China); Qi, Fei [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui (China); State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui (China)

2010-09-15

279

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

280

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

281

Pretreatment effects of trichloroethylene on the dermal absorption of the biocide, triazine  

Microsoft Academic Search

Triazine is often added to cutting-fluid formulations in the metal-machining industry as a preservative. Trichloroethylene (TCE) is a solvent used for cleaning the cutting fluid or oil from the metal product. The purpose of this study was to examine the effect of TCE on the dermal absorption of triazine in an in vitro flow-through diffusion cell system. Skin sections were

Ronald E. Baynes; James L. Yeatts; James D. Brooks; Jim E. Riviere

2005-01-01

282

Deposition of Fe Ni nanoparticles on Al2O3 for dechlorination of chloroform and trichloroethylene  

Microsoft Academic Search

This research proposes an efficient method for depositing Fe Ni nanoparticles on Al2O3 microparticles to decompose containments in ground water, such as chloroform and trichloroethylene. The Fe Ni nanoparticles can be deposited onto the surface of Al2O3 microparticles by electroless plating technique. The reasons why the Fe Ni nanoparticles would be deposited on the surface of Al2O3 microparticles is to

Shu-Huei Hsieh; Jao-Jia Horng

2006-01-01

283

Effect of nitrogen source on growth and trichloroethylene degradation by methane-oxidizing bacteria  

Microsoft Academic Search

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

KUNG-HUI CHU; LISA ALVAREZ-COHEN

1998-01-01

284

Protective effects of N-acetylcysteine against carbon tetrachloride- and trichloroethylene-induced poisoning in rats  

Microsoft Academic Search

This research investigates the protective effect of N-acetylcysteine (NAC) against carbon tetrachloride (CCl4)- and trichloroethylene (TCE)-induced hepatotoxicity in rats. A single dose of 1.25 ml\\/kg of 20% CCl4 in corn oil, administered orally, or 20% TCE, administered intraperitoneally, produced significantly elevated levels of serum glutamic pyruvic transaminase (SGPT) and serum glutamic oxaloacetic transaminase (SGOT) activities. Histopathological examinations showed massive centrilobular

Chun Kwan Wong; Vincent E. C Ooi; Chong Kim Wong

2003-01-01

285

Trichloroethylene degradation by genetically engineered bacteria carrying cloned phenol catabolic genes  

Microsoft Academic Search

Pseudomonas putida BH was capable of degrading trichloroethylene (TCE) when grown on phenol, o-cresol, m-cresol or p-cresol, each of which induced the enzymes catalyzing the catechol catabolism through the meta-cleavage pathway. Various DNA fragments containing phenol\\/cresol catabolic genes cloned from this strain were introduced into Escherichia coli and P. putida strains by using plasmid vectors, and the resultant recombinants were

Masanori Fujita; Michihiko Ike; Jun-Ichi Hioki; Koji Kataoka; Masahiro Takeo

1995-01-01

286

Comparison of available benchmark dose softwares and models using trichloroethylene as a model substance  

Microsoft Academic Search

By using trichloroethylene as a model substance the U.S. EPA benchmark dose software was compared to the software by Crump and the software by Kalliomaa. Dose–response and dose–effect data on the liver, kidneys, central nervous system (CNS), and tumours were selected for the evaluation. Based on the present study the U.S. EPA software is preferable to the other softwares for

Agneta Falk Filipsson; Katarina Victorin

2003-01-01

287

Catalytic decomposition of trichloroethylene over Pt\\/Ni-catalyst under microwave heating  

Microsoft Academic Search

Microwave (MW)-activated catalytic reactor system was studied and the results were compared with that of a conventional system based on the thermal activation method. Trichloroethylene (TCE) was decomposed under various MW-powers supply. Results showed that there is an optimum film thickness that was loaded on supports in MW heating system. The threshold may be within 1–3?m. Lower temperature cannot activate

Hideaki Takashima; Martin Karches; Yoshinori Kanno

2008-01-01

288

Persulfate oxidation of trichloroethylene with and without iron activation in porous media  

Microsoft Academic Search

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°=2.6V). The column study presented here simulates persulfate oxidation of TCE in porous media (glass beads and a

Chenju Liang; I-Ling Lee; I-Yuang Hsu; Ching-Ping Liang; Yu-Ling Lin

2008-01-01

289

Biodegradation of trichloroethylene in continuous-recycle expanded-bed bioreactors  

Microsoft Academic Search

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

T. J. Phelps; J. J. Niedzielski; R. M. Schram; S. E. Herbes; D. C. White

1990-01-01

290

Effect of reduction temperature on the preparation of zero-valent iron aerogels for trichloroethylene dechlorination  

Microsoft Academic Search

Zero-valent iron (ZVI) aerogels have been synthesized by sol-gel method and supercritical CO2 drying, followed by H2 reduction in the temperature range of 350–500 °C. When applied to trichloroethylene (TCE) dechlorination, the ZVI aerogel\\u000a reduced at 370 °C showed the highest performance in the conditions employed in this study. Thus, the effect of reduction temperature\\u000a in preparing ZVI aerogels has

Jihye Ryu; Dong Jin Suh; Young-Kwon Park; Young-Woong Suh

2008-01-01

291

Combustion of trichloroethylene and dichloromethane over protonic zeolites: Influence of adsorption properties on the catalytic performance  

Microsoft Academic Search

The deep oxidation of dichloromethane (DCM) and trichloroethylene (TCE) over protonic zeolites (HA, HX, HY and H-ZSM-5) was studied in this work. Experiments were performed in dry air in the range 50–650°C in a pulsed microreactor. Catalytic activity was correlated with the capacity of adsorption of DCM and TCE as well as the strength and specificity of these interactions, which

Lorena Intriago; Eva Díaz; Salvador Ordóñez; Aurelio Vega

2006-01-01

292

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

293

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

294

Acute exposure to 50ppm toluene does not increase sleepiness.  

PubMed

The Pupillographic Sleepiness Test (PST) is a new neurophysiological method to assess sleepiness. In an exposure study to a constant exposure level of 50ppm toluene on 20 healthy men, our aim was to find out, if increased sleepiness could be seen with PST. PST was performed before and after 4.5h of exposure. General complaints were assessed with the Swedish Performance Evaluation System (SPES) self-assessment questionnaire, once before and during exposure. Values obtained during exposure were related to pre-exposure values. Parametric cross-over analysis of logarithmic Pupillary Unrest Index (PUI) values did not show an effect of toluene exposure. In a nonparametric cross-over analysis of SPES-scores a significant increase of the scores of unpleasant smell and irritation to the throat, but not of tiredness was found. In conclusion, acute exposure to 50ppm toluene, corresponding to the German threshold limit value, did not increase sleepiness. PMID:21783540

Muttray, Axel; Spelmeyer, Uwe; Hommel, Gerhard; Oesch, Franz; Jung, Detlev; Rose, Dirk-Matthias; Mayer-Popken, Otfried; Rossbach, Bernd; Letzel, Stephan

2005-05-01

295

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

296

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

297

Performance of trickle bed biofilters under high toluene loading  

SciTech Connect

The performance of two pelletized media biofilters, highly loaded with toluene, was evaluated in this study. Both biofilters were operated at the same influent concentration of 250 ppmv toluene. Biofilter `A` was operated at 1 minute EBRT and biofilter `B` at 0.67 minute EBRT. The impact of backwash duration on performance was studied for both biofilters, primarily the stability of performance between backwashings. This biofilter behavior indicated that increasing the backwash period from 1 to 2 hours was effective in improving the performance stability of both biofilters. This improved performance stability is due to reduction of short circuiting within the media, caused by accumulating biomass.

Sorial, G.A.; Smith, F.L.; Pandit, A.; Suidan, M.T.; Biswas, P.

1995-07-01

298

Chronic toluene misuse among Roma youth in Eastern Slovakia.  

PubMed

This report presents pilot data on toluene misuse among Roma (Gypsy) youth in eastern Slovakia. Twenty interviews were conducted with field social workers (FSWs) working in seven Roma settlements with a combined population of 17,050 people. An estimated 340 chronic toluene users, mostly males (90%, n = 306), were identified in the researched communities. FSWs reported that children younger than 10 years of age represented about 15% of users (n = 52) and that the majority of users (75%, n = 255) were between 10 and 25 years of age. Consequences of prolonged use on individuals and communities are discussed. The study's limitations are noted. PMID:21609147

Važan, Peter; Khan, Maria R; Poduška, Ond?ej; Stastná, Lenka; Miovský, Michal

2011-01-01

299

Synergistic effect of catalyst for oxidation removal of toluene.  

PubMed

A series of experiments was performed for toluene removal from a gaseous influent at the normal temperature and atmospheric pressure by decomposition due to dielectric barrier discharge generated non-thermal plasma, by using MnO(2)/gamma-Al(2)O(3) as catalyst. The removal efficiency of toluene was significantly increased by combining MnO(2)/gamma-Al(2)O(3) with NTP. At the same time, the goal of improving energy efficiency and decreasing O(3) from exhaust gas treatment was accomplished. PMID:19124193

Zhu, Tao; Li, Jian; Liang, Wenjun; Jin, Yuquan

2009-06-15

300

FORMATION OF POLYKETONES IN IRRADIATED TOLUENE/PROPYLENE/NOX/AIR MIXTURES  

EPA Science Inventory

A laboratory study was carried out to investigate the formation of polyketones in secondary organic aerosol from photooxidation of the aromatic hydrocarbon toluene, a major constituent of automobile exhaust. The laboratory experiments consisted of irradiating toluene/propylene...

301

Enhanced Anaerobic Biodegradation of Benzene-Toluene-Ethylbenzene-Xylene-Ethanol Mixtures in Bioaugmented Aquifer Columns  

Microsoft Academic Search

Methanogenic flowthrough aquifer columns were used to investigate the potential of bioaugmentation to enhance anaerobic benzene-toluene-ethylbenzene-xylene (BTEX) degradation in groundwater contaminated with ethanol-blended gasoline. Two different methanogenic consortia (enriched with benzene or toluene and o-xylene) were used as inocula. Toluene was the only hydrocarbon degraded within 3 years in columns that were not bioaugmented, although anaerobic toluene degradation was observed

M. L. B. Da Silva; P. J. J. Alvarez

2004-01-01

302

Nigella sativa and Derived Thymoquinone Prevents Hippocampal Neurodegeneration After Chronic Toluene Exposure in Rats  

Microsoft Academic Search

The aim of this study was designed to investigate the possible beneficial effects of Nigella sativa (NS) and derived thymoquinone (TQ) on neurodegeneration in hippocampus after chronic toluene exposure in rats. The rats were\\u000a randomly allotted into one of four experimental groups: A (control), B (toluene treated), C (toluene treated with NS) and\\u000a D (toluene treated with TQ); each group

Mehmet Kanter

2008-01-01

303

Acute exposure to 50 ppm toluene does not increase sleepiness  

Microsoft Academic Search

The Pupillographic Sleepiness Test (PST) is a new neurophysiological method to assess sleepiness. In an exposure study to a constant exposure level of 50ppm toluene on 20 healthy men, our aim was to find out, if increased sleepiness could be seen with PST. PST was performed before and after 4.5h of exposure. General complaints were assessed with the Swedish Performance

Axel Muttray; Uwe Spelmeyer; Gerhard Hommel; Franz Oesch; Detlev Jung; Dirk-Matthias Rose; Otfried Mayer-Popken; Bernd Rossbach; Stephan Letzel

2005-01-01

304

TOLUENE DOSE-EFFECT META ANALYSIS AND IMPORTANCE OF EFFECTS  

EPA Science Inventory

TOLUENE DOSE-EFFECT META ANALYSES AND IMPORTANCE OF EFFECTS Benignus, V.A., Research Psychologist, ORD, NHEERL, Human Studies Division, 919-966-6242, benignus.vernon@epa.gov Boyes, W.K., Supervisory Health Scientist, ORD, NHEERL, Neurotoxicology Division 919-541-...

305

Decomposition of toluene by streamer corona discharge with catalyst  

Microsoft Academic Search

The improvement in the decomposition of volatile organic compounds was investigated by combining discharge plasma with photocatalyst (TiO2). A DC streamer corona plasma reactor combined with photocatalyst pellet layer was developed. It was found that the combination of the plasma and TiO2 was effective for improving toluene decomposition when the streamers cover the surface of the pellet layer.

Duan Li; Daisuke Yakushiji; Seiji Kanazawa; Toshikazu Ohkubo; Yukiharu Nomoto

2002-01-01

306

Benzene, toluene and xylene biodegradation by Pseudomonas putida CCMI 852  

Microsoft Academic Search

A minimal liquid medium containing benzene (B), toluene (T) and xylene (X) and mixtures thereof, was used to evaluate degradation activity of Pseudomonas putida CCMI 852 containing a TOL plasmid. Experiments were developed with B, T and X (100 mg L-1), with mixtures of BT, BX, and TX (50 + 50 mg L-1 each) and BTX (33.3 + 33.3 +

Marcelo Henrique Otenio; Maria Teresa Lopes da Silva; Maria Luiza Oliveira Marques; José Carlos Roseiro; Ederio Dino Bidoia

2005-01-01

307

The geochemical effects of benzene, toluene, and xylene (BTX) biodegradation  

Microsoft Academic Search

The geochemical effects of microbially mediated degradation of aromatic hydrocarbons were observed as changes in solution composition of an artificial groundwater in packed-sand laboratory columns. Benzene, toluene, and xylene, both individually and in a combined fashion, were used as substrates in biodegradation experiments conducted under oxygenated and anoxic conditions in columns filled with quartz, calcite, or Fe3+-coated quartz sand. Typically,

Walton R. Kelly; Janet S. Herman; Aaron L. Mills

1997-01-01

308

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

309

Hydrodealkylation of toluene using hydrogen-rich reformer gas  

Microsoft Academic Search

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

V. I. Golubyatnikov; V. M. Kapustin; A. I. Lugovskoi

1988-01-01

310

The Oxidative and Morphological Effects of High Concentration Chronic Toluene Exposure on Rat Sciatic Nerves  

Microsoft Academic Search

This study was designed to investigate the effects of chronic toluene inhalation in high concentration on lipid peroxidation, antioxidant enzyme activities and ultrastructural changes in the sciatic nerves of rats. Male Wistar albino rats (150–250 g) were divided in two experimental groups: the control and the toluene treated group (n=10 for each). Toluene treatment was performed by inhalation of 3000

Omer Coskun; Sukru Oter; Ahmet Korkmaz; Ferah Armutcu; Mehmet Kanter

2005-01-01

311

Specific bronchial reactivity to toluene diisocyanate: relationship with baseline clinical findings  

Microsoft Academic Search

One hundred and fourteen subjects with asthma induced by toluene diisocyanate were identified and the pattern of their bronchial responses to challenge with toluene diisocyanate was studied. An occupational type specific bronchial provocation test with toluene diisocyanate (10-25 parts per thousand million for 10-15 minutes) elicited an immediate response in 24, a late response in 50, and a dual response

P L Paggiaro; A Innocenti; E Bacci; O Rossi; D Talini

1986-01-01

312

Aqueous phase adsorption of toluene in a packed and fluidized bed of hydrophobic aerogels  

Microsoft Academic Search

Surface-treated hydrophobic silica aerogel granules (Cabot Nanogel®) are contacted by a downward flow of a dilute toluene–water solution in either a packed bed or an inverse fluidized bed mode. The toluene adsorption efficiency and capacity of the Nanogel granules in both the packed or inverse fluidized bed are studied. The results show that the major factors which affect the toluene

Ding Wang; Elisabeth McLaughlin; Robert Pfeffer; Y. S. Lin

2011-01-01

313

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

Code of Federal Regulations, 2010 CFR

...Toluene sulfonamide bis-phe-nol A epoxy adduct. 721.1850 Section 721.1850 ...Toluene sulfonamide bis-phe-nol A epoxy adduct. (a) Chemical substances and significant...as toluene sulfonamide bisphenol A epoxy adduct (PMN P-90-113) is subject to...

2010-07-01

314

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

Code of Federal Regulations, 2010 CFR

...Toluene sulfonamide bis-phe-nol A epoxy adduct. 721.1850 Section 721.1850 ...Toluene sulfonamide bis-phe-nol A epoxy adduct. (a) Chemical substances and significant...as toluene sulfonamide bisphenol A epoxy adduct (PMN P-90-113) is subject to...

2009-07-01

315

STRUCTURE, VIBRATIONAL, AND CALORICAL PROPERTIES OF FULLERENE C60IN TOLUENE SOLUTION  

Microsoft Academic Search

The structure, vibrational and calorical properties of fullerene C60 in toluene solution were investigated both experimentally and theoretically in detail. The aggregation kinetics results indicated that the structure of C60 aggregates in toluene could be described as a fractal system. The electronic absorption spectra of C60 toluene solution with different concentration testify to the molecular character of absorption. The vibrational

Yu I. Prylutskyy; S. S. Durov; L. A. Bulavin; I. I. Adamenko; K. O. Moroz; A. Graja; A. Bogucki; P. Scharf

2001-01-01

316

RELATIONSHIP BETWEEN OZONE FORMATION AND TOLUENE DECOMPOSITION EFFICIENCY IN A ZEOLITE-HYBRID PLASMA REACTOR  

Microsoft Academic Search

A zeolite-hybrid plasma reactor showed the excellent performance for the toluene decompositio n by the cyclic operations such as long time toluene adsorption followed by short time plasma discharge. In particular, the decomposition efficiency of toluene was enhanced by placing the zeolite in the downward position of the plasma region rather than placing that in the upward position. On the

A. OGATA; H. H. KIM; S. M. OH; H. EINAGA; S. FUTAMURA

2006-01-01

317

Benzylsuccinate Formation as a Means of Anaerobic Toluene Activation by Sulfate-Reducing Strain PRTOL1  

PubMed Central

Permeabilized cells of toluene-mineralizing, sulfate-reducing strain PRTOL1 catalyzed the addition of toluene to fumarate to form benzylsuccinate under anaerobic conditions. Recent in vitro studies with two toluene-mineralizing, denitrifying bacteria demonstrated the same fumarate addition reaction and indicated that it may be the first step of anaerobic toluene degradation. This study with strain PRTOL1 shows that anaerobic toluene activation by fumarate addition occurs in bacteria as disparate as sulfate-reducing and denitrifying species (members of the delta and beta subclasses of the Proteobacteria, respectively).

Beller, H. R.; Spormann, A. M.

1997-01-01

318

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

319

Photo-activated luminescence sensor and method of detecting trichloroethylene and related volatile organochloride compounds  

DOEpatents

A sensor for detecting trichloroethylene and related volatile organochloride compounds uses a photo-activator that produces a photo-product complex with the contaminant. Characteristics of the light emitted from the complex will indicate the presence of the contaminant. A probe containing the photo-activator has an excitation light interface and a contaminant interface. One particular embodiment uses a porous membrane as the contaminant interface, so that the contaminant can migrate therethrough to the photo-activator and thereby form the complex.

Dinh, Tuan V. (Knoxville, TN)

1996-01-01

320

Photo-activated luminescence sensor and method of detecting trichloroethylene and related volatile organochloride compounds  

DOEpatents

A sensor for detecting trichloroethylene and related volatile organochloride compounds uses a photo-activator that produces a photo-product complex with the contaminant. Characteristics of the light emitted from the complex will indicate the presence of the contaminant. A probe containing the photo-activator has an excitation light interface and a contaminant interface. One particular embodiment uses a porous membrane as the contaminant interface, so that the contaminant can migrate there through to the photo-activator and thereby form the complex. 23 figs.

Dinh, T.V.

1996-06-11

321

A meta-analysis of occupational trichloroethylene exposure and liver cancer  

Microsoft Academic Search

Objective  Findings from epidemiologic studies of trichloroethylene (TCE) exposure and liver cancer have been inconsistent. To quantitatively\\u000a evaluate this association and to examine sources of heterogeneity, we conducted a meta-analysis of occupational studies of\\u000a TCE exposure and liver\\/biliary tract cancer.\\u000a \\u000a \\u000a \\u000a Methods  We identified 14 occupational cohort studies of TCE exposed workers and one case-control study that met our inclusion criteria.\\u000a Nine studies

Dominik D. Alexander; Michael A. Kelsh; Pamela J. Mink; Jeffrey H. Mandel; Rupa Basu; Michal Weingart

2007-01-01

322

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

1995-01-01

323

In vitro metabolism of benzene, toluene, and xylene in rat liver  

SciTech Connect

A headspace gas chromatographic method was used to study the metabolism of benzene, toluene, and m-xylene in rat liver. Metabolism of benzene was lower than that of toluene, or m-xylene. Investigating metabolic rates of subcellular fractions, it was found that glutathione and glutathione S-transferase in the cytosol are involved in metabolism of benzene and toluene by microsomes. When both benzene and toluene are present in the incubation medium, they act as inhibitors of each others metabolism. Toluene and m-xylene metabolism were induced by the pretreatment of rats with phenobarbital (75 mg/kg), or 3-methylcholanthrene (25 mg/kg), or Aroclor 1254 (75 mg/kg) for 3 days, whereas benzene metabolism was not induced by all pretreatments. Another series of experiments was conducted to compare the effects of benzene, toluene, and xylene pretreatment on liver metabolism. In vivo metabolism of /sup 14/C-toluene and possible covalent binding of /sup 14/C-toluene to microsomes were also investigated. /sup 14/C-toluene when incubated with liver microsomes in the presence of a NADPH generating system formed benzylalcohol and cresols. Some of the radioactivity was covalently bound preferentially to microsomal proteins. The binding process required cytochrome P-450 dependent mixed function oxidases. This study suggests that toluene is metabolized to several reactive intermediates by liver microsomal enzymes and these metabolites are responsible for the covalent binding to macromolecules which represents a subcellular mechanism by which toluene may express its own in vivo toxicity.

Pathiratne, A.

1985-01-01

324

Structural Magnetic Resonance Imaging in an adult cohort following prenatal and early postnatal exposure to tetrachloroethylene (PCE)-contaminated drinking water.  

PubMed

This population-based retrospective cohort study examined Structural Magnetic Resonance Imaging (MRI) of the brain 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 Geographic Information System (GIS) methodology. Brain imaging was performed on 26 exposed and 16 unexposed subjects. Scans were acquired on a Philips 3T whole body scanner using the ADNI T1-weighted MP-RAGE scan. The scans were processed by FreeSurfer version 4.3.1 software to obtain measurements of specific brain regions. There were no statistically significant differences between exposed and unexposed subjects on the measures of white matter hypointensities (?: 127.5mm(3), 95% CI: -259.1, 1514.0), white matter volumes (e.g. total cerebral white matter: ?: 21230.0mm(3), 95% CI: -4512.6, 46971.7) or gray matter volumes (e.g. total cerebral gray matter: ?: 11976.0mm(3), 95% CI: -13657.2, 37609.3). The results of this study suggest that exposure to PCE during gestation and early childhood, at the levels observed in this population, is not associated with alterations in the brain structures studied. PMID:23571160

Janulewicz, Patricia A; Killiany, Ronald J; White, Roberta F; Martin, Brett M; Winter, Michael R; Weinberg, Janice M; Aschengrau, Ann

2013-01-01

325

Structural Magnetic Resonance Imaging in an Adult Cohort Following Prenatal and Early Postnatal Exposure to Tetrachloroethylene (PCE)-contaminated Drinking Water  

PubMed Central

This population-based retrospective cohort study examined Structural Magnetic Resonance Imaging (MRI) of the brain 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 Geographic Information System (GIS) methodology. Brain imaging was performed on 26 exposed and 16 unexposed subjects. Scans were acquired on a Philips 3T whole body scanner using the ADNI T1-weighted MP-RAGE scan. The scans were processed by FreeSurfer version 4.3.1 software to obtain measurements of specific brain regions. There were no statistically significant differences between exposed and unexposed subjects on measures of white matter hypointensities (?: 127.5 mm3, 95% CI: ?259.1, 1514.0), white matter volumes (e.g. total cerebral white matter: ?: 21230.0 mm3, 95% CI: ?4512.6, 46971.7) or gray matter volumes (e.g. total cerebral gray matter: ?: 11976.0 mm3, 95% CI: ?13657.2, 37609.3). The results of this study suggest that exposure to PCE during gestation and early childhood, at the levels observed in this population, is not associated with alterations in the brain structures studied.

Janulewicz, Patricia A; Killiany, Ronald J; White, Roberta F; Martin, Brett M; Winter, Michael R; Weinberg, Janice M; Aschengrau, Ann

2013-01-01

326

Performances of toluene removal by activated carbon derived from durian shell.  

PubMed

In the effort to find alternative low cost adsorbent for volatile organic vapors has prompted this research in assessing the effectiveness of activated carbon produced from durian shell in removing toluene vapors. Durian shells were impregnated with different concentrations of H3PO4 followed by carbonization at 500 °C for 20 min under nitrogen atmosphere. The prepared durian shell activated carbon (DSAC) was characterized for its physical and chemical properties. The removal efficiency of toluene by DSAC was performed using different toluene concentrations. Results showed that the highest BET surface area of the produced DSAC was 1404 m2/g. Highest removal efficiency of toluene vapors was achieved by using DSAC impregnated with 30% of acid concentration heated at 500 °C for 20 min heating duration. However, there is insignificant difference between removal efficiency of toluene by DSAC and different toluene concentrations. The toluene adsorption by DSAC was better fitted into Freundlich model. PMID:20884200

Tham, Y J; Latif, Puziah Abdul; Abdullah, A M; Shamala-Devi, A; Taufiq-Yap, Y H

2011-01-01

327

Collision-induced CH bond dissociation in highly excited toluene  

NASA Astrophysics Data System (ADS)

The bond dissociation of highly excited toluene colliding with argon has been studied by use of classical trajectory procedures. All 39 stretches and bends of toluene are included in the model. Both methyl and adjacent ring CH bonds, each with the initial vibrational energy 0.10 eV below the dissociation threshold, are in interaction with Ar. The dissociation probabilities are PCH methyl = 0.14 and PCH ring = 0.19 at 300 K. The CH methyl bond dissociation is a result of the Ar-CH methyl collision transferring a large amount of energy (? kT) via the T ? V pathway. The activation of CH ring toward dissociation occurs through a series of small steps gaining energy intramolecularly from the methyl end. The Ar-CH ring interaction is unimportant in transferring energy to the CH ring stretch and in turn causing the bond dissociation.

Ree, J.; Kim, Y. H.; Shin, H. K.

2004-08-01

328

TEM Study of Lizardite1T Particles in Toluene Solvent  

Microsoft Academic Search

Micrometer sized particles of lizardite-1T phase are observed in toluene solvent. Phase identification is carried out by selected-area\\u000a electron diffraction experiment and simulation. TEM study shows that the particles are in flake forms with the (001) preferred\\u000a orientation. Energy-dispersive X-ray spectra reveal some particles containing Mg and Si, and others containing Al and Si.\\u000a Structural deterioration of the lizardite-1T phase

J. Yan; X. Z. Li; J. Y. Jiang; L. Tan

2010-01-01

329

The effects of toluene and alcohol on psychomotor performance  

Microsoft Academic Search

Eight male subjects took part in four experimental sessions in an exposure chamber to assess the effects of toluene (80 p.p.m.) and alcohol (0.4 ml per kg body weight) individually and in combination on four measures of performance and also on mood. Alcohol caused a significant deterioration over the exposure session in performance on pursuit tracking and visual search tasks

NICOLA CHERRY; J. D. JOHNSTON; HELEN VENABLES; H. A. WALDRON; L. BUCK; C. J. MACKAY

1983-01-01

330

Comparison of measurement methods for benzene and toluene  

NASA Astrophysics Data System (ADS)

Diffusive sampling and active (pumped) sampling (tubes filled with Tenax TA or Carbopack B) were compared with an automatic BTX instrument (Chrompack, GC/FID) for measurements of benzene and toluene. The measurements were made during differing pollution levels and different weather conditions at a roof-top site and in a densely trafficked street canyon in Stockholm, Sweden. The BTX instrument was used as the reference method for comparison with the other methods. Considering all data the Perkin-Elmer diffusive samplers, containing Tenax TA and assuming a constant uptake rate of 0.406 cm3 min-1, showed about 30% higher benzene values compared to the BTX instrument. This discrepancy may be explained by a dose-dependent uptake rate with higher uptake rates at lower dose as suggested by laboratory experiments presented in the literature. After correction by applying the relationship between uptake rate and dose as suggested by Roche et al. (Atmos. Environ. 33 (1999) 1905), the two methods agreed almost perfectly. For toluene there was much better agreement between the two methods. No sign of a dose-dependent uptake could be seen. The mean concentrations and 95% confidence intervals of all toluene measurements (67 values) were (10.80±1.6) ?g m -3 for diffusive sampling and (11.3±1.6) ?g m -3 for the BTX instrument, respectively. The overall ratio between the concentrations obtained using diffusive sampling and the BTX instrument was 0.91±0.07 (95% confidence interval). Tenax TA was found to be equal to Carbopack B for measuring benzene and toluene in this concentration range, although it has been proposed not to be optimal for benzene. There was also good agreement between the active samplers and the BTX instrument.

Wideqvist, U.; Vesely, V.; Johansson, C.; Potter, A.; Brorström-Lundén, E.; Sjöberg, K.; Jonsson, T.

331

Thermal effects on the electric deflection of toluene molecules  

NASA Astrophysics Data System (ADS)

A series of precise electric deflection experiments were done on a supersonic beam of toluene molecules in several expansion conditions and field strengths. We analyzed the effect of a gradual rotational cooling on the evolution of the beam profile by use of the available theories of asymmetric-top dipoles in electric fields. We have recorded from non-broadened (warm) to very broad and asymmetric (cold) profiles, and discussed this effect in terms of the Stark perturbation on the rotational motion.

Carrera, Álvaro; Mobbili, Marcos; Moriena, Gustavo; Marceca, Ernesto

2008-12-01

332

Activity of variously supported Rh catalysts for toluene steam dealkylation  

Microsoft Academic Search

The steam dealkylation of toluene to benzene was tested on rhodium supported on 15 different supports, mostly silica and chromia with or without alkali additive. Best stability was obtained with potassium-promoted ..gamma..-chromia, which lost 0.15%\\/hr activity at 461°C and 0.77%\\/hr activity at 576°C in 45-50 hr runs. Generally, catalysts prepared by adsorption from excess solution were more stable than catalysts

P. Beltrame; I. Ferino; L. Forni; S. Torrazza

1979-01-01

333

Serum proteomic analysis reveals potential serum biomarkers for occupational medicamentosa-like dermatitis caused by trichloroethylene.  

PubMed

Trichloroethylene (TCE) is an industrial solvent with widespread occupational exposure and also a major environmental contaminant. Occupational medicamentosa-like dermatitis induced by trichloroethylene (OMLDT) is an autoimmune disease and it has become one major hazard in China. In this study, sera from 3 healthy controls and 3 OMLDT patients at different disease stages were used for a screening study by 2D-DIGE and MALDI-TOF-MS/MS. Eight proteins including transthyretin (TTR), retinol binding protein 4 (RBP4), haptoglobin, clusterin, serum amyloid A protein (SAA), apolipoprotein A-I, apolipoprotein C-III and apolipoprotein C-II were found to be significantly altered among the healthy, acute-stage, healing-stage and healed-stage groups. Specifically, the altered expression of TTR, RBP4 and haptoglobin were further validated by Western blot analysis and ELISA. Our data not only suggested that TTR, RBP4 and haptoglobin could serve as potential serum biomarkers of OMLDT, but also indicated that measurement of TTR, RBP4 and haptoglobin or their combination could help aid in the diagnosis, monitoring the progression and therapy of the disease. PMID:24960064

Huang, Peiwu; Ren, Xiaohu; Huang, Zhijun; Yang, Xifei; Hong, Wenxu; Zhang, Yanfang; Zhang, Hang; Liu, Wei; Huang, Haiyan; Huang, Xinfeng; Wu, Desheng; Yang, Linqing; Tang, Haiyan; Zhou, Li; Li, Xuan; Liu, Jianjun

2014-08-17

334

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

335

Modeling biodegradation of toluene in rotating drum biofilter.  

PubMed

Rotating drum biofilters (RDBs) are cost-effective for control of emissions of volatile organic compounds (VOCs) from waste gas streams. In this paper, a dynamic mathematical model is presented which simulates and predicts the variation in performance of a multi-layer RDB with time on the basis of the two-film theory. The model takes into account factors including biofilm growth and biomass loss, and a changing biofilm surface area and thickness assuming quasi-steady-state conditions in the two-phase system and uniform bacterial population. Toluene was assumed to be the only rate-limiting substrate. The model equations for the gas-phase mass balance and biofilm growth were solved using MATLAB based on the fourth-fifth-order Runge-Kutta technique, and the concentration profiles in the biofilms were obtained using the method of orthogonal collocation. Simulation results showed that the toluene removal efficiency decreased with increased toluene loading or increased duration of operation of the biofilter. Calculation results were compared to the experimental results, which demonstrated that the dynamic model provided a good simulation of the performance of the biofilter. PMID:17163052

Yang, C P; Chen, H; Zeng, G M; Qu, W; Zhong, Y Y; Zhu, X; Suidan, M T

2006-01-01

336

Removal of Trichloroethylene by Activated Carbon in the Presence and Absence of TiO2 Nanoparticles  

EPA Science Inventory

Nanoparticles (NPs) are emerging as a new type of contaminant in water and wastewater. The fate of titanium dioxide nanoparticles (TiO2NPs) in a granular activated carbon (GAC) adsorber and their impact on the removal of trichloroethylene (TCE) by GAC was investigated...

337

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...

338

Evaluating human variability in chemical risk assessment: hazard identification and dose-response assessment for noncancer oral toxicity of trichloroethylene  

Microsoft Academic Search

Human variability can be addressed during each stage in the risk assessment of chemicals causing noncancer toxicities. Noncancer toxicities arising from oral exposure to trichloroethylene (TCE) are used in this paper as a case study for exploring strategies for identifying and incorporating information about human variability in the chemical specific hazard identification and dose-response assessment steps. Toxicity testing in laboratory

H. A. Barton; C. D. Flemming; J. C. Lipscomb

1996-01-01

339

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. Microcosms a...

340

Use of Infrared Spectrometry to Determine the Effect of Trichloroethylene Resident Time on Desorption Rates from Flint Clay.  

National Technical Information Service (NTIS)

This laboratory based thesis investigated the desorption rate of trichloroethylene (TCE) from flint clay while varying the resident time of TCE exposed to the clay. It is thought that in long contaminated soil, a majority of contaminant mass will become e...

P. LaPuma

1994-01-01

341

Evaluation of the Potential Impact of Inhibition of Trichloroethylene Metabolism in the Liver on Extra-Hepatic Toxicity  

EPA Science Inventory

The interaction between trichloroethylene (TCE) and chloroform (CHCI3) is less than additive, with co-exposure to TCE and CHCl3 resulting in less hepatic and renal toxicity than observed with CHCl3 alone. Vapor uptake data demonstrate that co-exposure to CHCl3 decreases the rate ...

342

Key Issues in the Modes of Action and Effects of Trichloroethylene Metabolites for Liver and Kidney Tumorigenesis  

Microsoft Academic Search

Trichloroethylene (TCE) exposure has been associated with increased risk of liver and kidney can- cer in both laboratory animal and epidemiologic studies. The U.S. Environmental Protection Agency 2001 draft TCE risk assessment concluded that it is difficult to determine which TCE metabolites may be responsible for these effects, the key events involved in their modes of action (MOAs), and the

Jane C. Caldwell; Nagalakshmi Keshava

2006-01-01

343

Co-metabolic biodegradation of trichloroethylene by Methylosinus trichosporium is stimulated by low concentrations methane or methanol  

Microsoft Academic Search

Co-metabolic biodegradation of trichloroethylene by Methylosinus trichosporium OB3b was stimulated by low concentrations of methane (up to 70 µM) or methanol (up to 0.4 mM) but inhibited at higher concentrations of them. A kinetic equation describing the dual effects of methane or methanol is proposed and the relevant kinetic constants have been determined.

Jungmee Kang; EunYeol Lee; Sunghoon Park

2001-01-01

344

Fragmentation of three isotopic toluene monocations in the 15–100 eV photon energy range  

Microsoft Academic Search

The dissociative photoionization of toluene-h8, toluene-?-d3 and toluene-d8 was studied within the 15–100 eV photon energy range using monochromatized synchrotron radiation as excitation source and a reflectron time-of-flight mass spectrometer in both electrostatic mirror and linear modes. Peak profile analyses of the linear mode spectra provided information on the kinetic energy release and, in some cases, the percentage of mono-

Thomas A Field; François Dulieu; Jean-Hugues Fillion; Jean-Louis Chotin; Stéphane Douin; Jean-Louis Lemaire; Sydney Leach

1999-01-01

345

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

2013-08-01

346

Different genes influence toluene- and ethanol-induced locomotor impairment in C. elegans*  

PubMed Central

Background The abused volatile solvent toluene shares many behavioral effects with classic central nervous system depressants such as ethanol. Similarities between toluene and ethanol have also been demonstrated using in vitro electrophysiology. Together, these studies suggest that toluene and ethanol may be acting, at least in part, via common mechanisms. Methods We used the genetic model, C. elegans, to examine the behavioral effects of toluene in a simple system, and used mutant strains known to have altered responses to other CNS depressants to examine the involvement of those genes in the motor effects induced by toluene. Results Toluene vapor brings about an altered pattern of locomotion in wild-type worms that is visibly distinct from that generated by ethanol. Mutants of the slo-1, rab-3 and unc-64 genes that are resistant to ethanol or the volatile anesthetic halothane show no resistance to toluene. A mutation in the unc-79 gene results in hypersensitivity to ethanol, halothane and toluene indicating a possible convergence of mechanisms of the three compounds. We screened for, and isolated, two mutations that generate resistance to the locomotor depressing effects of toluene and do not alter sensitivity to ethanol. Conclusions In C. elegans, ethanol and toluene have distinct behavioral effects and minimal overlap in terms of the genes responsible for these effects. These findings demonstrate that the C. elegans model system provides a unique and sensitive means of delineating both the commonalities as well as the differences in the neurochemical effects of classical CNS depressants and abused volatile inhalants.

Davies, Andrew G.; Friedberg, Ryan I.; Gupta, Hersh; Chan, Chung-Lung; Shelton, Keith L.; Bettinger, Jill C.

2011-01-01

347

Common induction and regulation of biphenyl, xylene/toluene, and salicylate catabolism in Pseudomonas paucimobilis.  

PubMed Central

A strain of Pseudomonas paucimobilis (strain Q1) capable of utilizing biphenyl was isolated from soil. This strain grew not only on substituted biphenyls, but also on salicylate, xylene or toluene or both (xylene/toluene), and substituted benzoates. Evidence is presented that the catabolism of biphenyl, xylene/toluene, and salicylate is regulated by a common unit in this strain. The catabolism of biphenyl, xylene/toluene, and salicylate is interrelated, since benzoate and toluate are common metabolic intermediates of biphenyl and xylene/toluene, and salicylate is produced from 2-hydroxybiphenyl (o-phenylphenol). All the oxidative enzymes of the biphenyl, xylene/toluene, and salicylate degradative pathways were induced when the cells were grown on either biphenyl, xylene/toluene or salicylate. The P. paucimobilis Q1 cells showed induction of the meta-cleavage enzymes of both 2,3-dihydroxybiphenyl and catechol. Biphenyl-negative derivatives of strain Q1 were simultaneously rendered xylene/toluene and salicylate negative, whereas reversion to the biphenyl-positive character of such derivatives invariably led to a xylene/toluene- and salicylate-positive phenotype. Growth of the P. paucimobilis Q1 cells with benzoate as a sole carbon source allowed the induction of only the ortho pathway enzymes, suggesting that biphenyl, xylene/toluene, or salicylate specifically induced the meta pathway enzymes for the oxidative degradation of these compounds.

Furukawa, K; Simon, J R; Chakrabarty, A M

1983-01-01

348

Biotechnical Approach to Studies on the Biodegradation of Chlorobenzenes and Trichloroethylene.  

National Technical Information Service (NTIS)

The absolute stereochemistry of the chiral dihydrodiols formed from ortho- and meta-dichlorobenzene were determined. Both diols were found to be enantiomerically pure with 1S,2S absolute configuration. Toluene-grown cells of Pseudomonas putida F1 and Pseu...

D. T. Gibson

1992-01-01

349

Kinetics of toluene degradation by a nitrate-reducing bacterium isolated from a groundwater aquifer.  

PubMed

Groundwater from a xylene-contaminated acquifer was enriched in the laboratory in the presence of toluene, xylenes, ethylbenzene, and benzene. A pure culture that degrades toluene and m-xylene under nitrate-reducing conditions was isolated. Fatty acid analysis, 16S rRNA sequencing, and morphological traits indicate that the isolate was a strain of Azoarcus tolulyticus. The kinetics of toluene degradation under nitrate-reducing conditions by this isolate was determined. Nitrate reduction does not proceed beyond nitrite. Nitrate and toluene are substrate limiting at low concentrations, whereas toluene, nitrate, and nitrite are inhibitory at high concentrations. Several inhibition models were compared to experimental data to represent inhibition by these substrates. A kinetic model for toluene and nitrate degradation as well as for cell growth and nitrite production was developed and compared to experimental data. The results of this work may find important application in the remediation of groundwater aquifers contaminated with aromatic hydrocarbons. PMID:18636447

Elmén, J; Pan, W; Leung, S Y; Magyarosy, A; Keasling, J D

1997-07-01

350

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

351

Comparative Study on the Implication of Three Nanoparticles on the Removal of Trichloroethylene by Adsorption - The Pilot and Rapid Small-Scale Column Tests  

EPA Science Inventory

The impact of three commercially-available nanoparticles (NPs) on trichloroethylene (TCE) adsorption onto granular activated carbon (GAC) was investigated. TCE Adsorption isotherm and column breakthrough experiments were conducted in the presence and absence of silicon dioxide (S...

352

ESTABLISHING CHANGES IN METABOLISM OF CARBON TETRACHLORIDE IN THE PRESENCE OF TRICHLOROETHYLENE IN THE RAT THROUGH THE USE OF PHYSIOLOGICALLY BASED PHARMACOKINETIC (PBPK) MODELING  

EPA Science Inventory

Toxicological interactions of chemicals can affect metabolism, often decreasing overall associated metabolic rates; and changes in metabolism can be evaluated through the use of mathematical models. Trichloroethylene (TCE) and carbon tetrachloride (CCl4) are common co...

353

Evaluation of the Role of Peroxisome Proliferator-Activated Receptor a (PPARa) in Mouse Liver Tumor Induction by Trichloroethylene and Metabolites  

EPA Science Inventory

Trichloroethylene (TCE) is an industrial solvent and a widespread environmental contaminant. Induction of liver cancer in mice by TCE is thought to be mediated by two metabolites, dichloroacetate (DCA) and trichloroacetate (TCA), both of which are themselves mouse liver carcinoge...

354

Bioaugmentation of the phyllosphere for the removal of toluene from indoor air  

Microsoft Academic Search

The removal of airborne toluene by means of the phyllosphere of Azalea indica augmented with a toluene-degrading enrichment culture of Pseudomonas putida TVA8 was studied. The 95% disappearance time [DT95%; the time in which an initial toluene concentration of 90 ppmv (339 mg.m 3) was removed in a batch experiment] was 75 h for Azalea plants. Under the same experimental conditions, DT95% of

L. De Kempeneer; B. Sercu; W. Vanbrabant; H. Van Langenhove; W. Verstraete

2004-01-01

355

Anaerobic Toluene Activation by Benzylsuccinate Synthase in a Highly Enriched Methanogenic Culture  

PubMed Central

Permeabilized cells of a highly enriched, toluene-mineralizing, methanogenic culture catalyzed the addition of toluene to fumarate to form benzylsuccinate under anaerobic conditions. The specific in vitro rate of benzylsuccinate formation was >85% of the specific in vivo rate of toluene consumption. This is the first report of benzylsuccinate synthase activity in a methanogenic culture; the activity has previously been reported to occur in denitrifying, sulfate-reducing, and anoxygenic phototrophic bacteria.

Beller, Harry R.; Edwards, Elizabeth A.

2000-01-01

356

Two New Mycobacterium Strains and Their Role in Toluene Degradation in a Contaminated Stream  

Microsoft Academic Search

Two toluene-degrading strains, T103 and T104, were isolated from rock surface biomass in a freshwater stream contaminated with toluene. The strains exhibit different capacities for degradation of toluene and other aromatic compounds and have characteristics of the genus Mycobacterium. Both are aerobic, rod-shaped, gram-positive, nonmotile, and acid-alcohol fast and produce yellow pigments. They have mainly straight-chain saturated and monounsaturated fatty

STEPHEN T.-L. TAY; HAROLD F. HEMOND; MARTIN F. POLZ; COLLEEN M. CAVANAUGH; INDHIRA DEJESUS; LEE R. KRUMHOLZ

1998-01-01

357

Reported survival with severe mixed acidosis and hyperlactemia after toluene poisoning  

PubMed Central

Lactic acidosis is a recognized complication of the inhalant abuse such as toluene, especially in patients with renal insufficiency. We report a case of severe metabolic acidosis and hyperlactemia due to toluene sniffing. The favorable outcome, despite extremely poor clinical symptoms, signs, laboratory and radiological findings, was unexpected. Specific aspects of the clinical course are addressed. Toluene sniffing should be considered in evaluating sever metabolic acidosis. Favorable outcome could be achieved with early diagnosis and proper interventions.

Omar, Amr S.; Rahman, Masood ur; Abuhasna, Said

2011-01-01

358

Ion insertion into ionic liquid supported toluene generated by electrochemical redox reaction  

Microsoft Academic Search

Ion transfer across the toluene|water, toluene–ionic liquid mixture|water and ionic liquid|water boundary generated by electrochemical redox reaction of tert-butylferrocene (tBuFc) was studied with the glassy carbon (GC) electrode partially covered by the organic liquid deposit and immersed in the aqueous electrolyte solution. The electrooxidation of the redox probe in toluene deposit is followed by ejection of newly formed cation into

Galyna Shul; Wojciech Adamiak; Marcin Opallo

2008-01-01

359

The neurotoxicity of toluene: EEG changes in rats exposed to various concentrations.  

PubMed Central

Workers exposed to toluene develop many central and autonomic nervous symptoms. It has been suggested that the effects of toluene on the central nervous system may be detectable by EEG. In the present experiments, changes in EEG and behaviour of rats exposed to toluene were monitored in an attempt to clarify the relationship between exposure to toluene and central nervous system reaction. Chronically implanted electrodes were used in Wistar albino male rats to record EEG in cortex and hippocampus, cervical EEG and pulse rate. The rats were exposed to 4000 ppm, 2000 ppm and 1000 ppm toluene vapour for four hours. The sleep cycle was divided into five phases (wakeful, spindle, slow-wave, preparadoxical and paradoxical) judged by the cortical and hippocampal EEGs, the cervical EMG, and behaviour. This classification should be useful in assessment of the effects of toluene on the central nervous system. In our experiments, the changes in the sleep cycle suggest that 4000 ppm and 2000 ppm of toluene vapour disturb the sleep, and 1000 ppm of toluene vapour prevents sleep entering the slow-wave phase but facilitates its entry into the paradoxical phase. The changes of EEG components were peculiar to each concentration. The results suggest, in effect, that analysis of the changes in the EEG components would be helpful as an index to the reaction of the central nervous system to toluene vapour.

Takeuchi, Y; Hisanaga, N

1977-01-01

360

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

361

Removal of toluene vapour using agro-waste as biofilter media.  

PubMed

Biodegradation of toluene vapour was investigated in a laboratory scale biofilter packed with cylindrical pieces of yellow-gram (Cajanus cajan) stalk. Inlet concentrations and volumetric flow rates of toluene were varied from 2.56 to 34.73 g/m3 and 0.18 to 0.24 m3/h, respectively. The steady state was achieved within seven days and the degradation of toluene followed an exponential behaviour with time. Elimination capacity increased and tended towards a constant value but removal efficiency decreased with increase in inlet toluene loading. Depending upon loading rate, the process was either mass transfer or reaction-controlled. PMID:16516463

Singh, R S; Agnihotri, S S; Upadhyay, S N

2006-12-01

362

Investigation on Conductance Behavior of Water\\/Dioctyl Sulfosuccinate Sodium Salt\\/Alkanol\\/Toluene Reverse Microemulsions  

Microsoft Academic Search

The conductivity (?) measurement was carried out on water\\/dioctyl sulfosuccinate sodium salt (DOSS)\\/heptanol (decanol)\\/toluene\\u000a reverse microemulsions. Addition of toluene was distinctly observed to inhibit the conductance percolation of water\\/DOSS\\/decanol\\/toluene\\u000a systems. The effect of additives (sodium chloride, sodium salicylate and sodium cholate) with various concentrations on the\\u000a conductivity behavior of water\\/DOSS\\/heptanol (decanol)\\/toluene systems was also investigated and discussed. The conductivity\\u000a of

Jie-xiang LiuHai-jiao; Hai-jiao Zhang; Xiao-guang Zhang; En-shan Han

2011-01-01

363

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

364

Degradation of Trichloroethylene by Methanol-Grown Cultures of Methylosinus trichosporium OB3b PP358  

PubMed Central

A soluble methane monooxygenase-constitutive mutant strain of Methylosinus trichosporium OB3b, strain PP358, was grown with methanol as the carbon source, and the kinetics of trichloroethylene (TCE) degradation were determined. PP358 exhibited high TCE degradation rates under both oxygen- and carbon-limiting conditions. The optimal pseudo first-order rate constant for TCE was comparable to the values measured for cells grown with methane. We found that growth under oxygen-limiting conditions results in increased accumulation of polyhydroxybutyrate, which in turn correlates with higher transformation capacities for TCE. It was also shown that methanol inhibits TCE degradation only at high concentrations. Thus, methanol-grown cultures of PP358 represent an efficient system for the biodegradation of chlorinated hydrocarbons.

Fitch, M. W.; Speitel, G. E.; Georgiou, G.

1996-01-01

365

Anaerobic biodegradation of trichloroethylene with the addition of sugar using activated carbon-fluidized beds  

SciTech Connect

Anaerobic biodegradation of trichloroethylene (TCE) was carried out in a two-stage granular activated carbon fluidized bed bioreactor. The intermediate products were identified as: dichloroethylene (DCE), vinyl chloride (VC), 1,2-dichloroethane (DCA) and chloroethane (CA). Of the three geometric isomers of DCE, the trans-1,2 dichloroethylene (TDCE) was found to be the most predominant species. The production of DCA suggested a diverted reaction sequence from the conventional sequential reductive dechlorination pathway postulated in the past literature. CA was believed to be a product of VC and/or DCA. The co-substrate glucose was implicated for this reaction specificity. Based on our data and on other's work, a modified degradation pathway for TCE in anaerobic environment is postulated. The quantitative product of CA strongly implied a potential for complete mineralization of TCE under reductive conditions.

Huang, Suxuan, D.

1989-01-01

366

Black shale as a sorbent for trichloroethylene and Cr(VI).  

PubMed

Black shale was examined as a natural sorbent for organic and inorganic contaminants. Trichloroethylene (TCE) could be removed well from the water by sorption onto the locally available black shale because of the high organic carbon content (5.2%) of the black shale in this study. Hexavalent chromium Cr(VI) was mainly removed by ionic sorption and reduction in batch and column experiments. Amphiphilic humic acid was also sorbed onto the black shale and could facilitate the sorption of TCE at the same time. Humic acid also enhanced the removal of Cr(VI) by reduction and sorption, but the amount of Cr(VI) adsorbed (mg kg(-1)) was smaller than that of TCE. Considering that the black shale in this study was used without any modifications and has a small surface area, black shale can be a cost-effective natural geosorbent and additive to remove organic contaminants and heavy metals. PMID:16035657

Min, J E; Lee, T; Choi, J; Park, J W

2005-06-01

367

Phytotoxicity and fate of 1,1,2-trichloroethylene: a laboratory study.  

PubMed

1,1,2-Trichloroethylene (TCE), a chlorinated organic contaminant, poses serious environmental concerns. A study was conducted to evaluate the phytotoxicity of TCE to a crop species and its fate in vermiculite. Growth bioassays were carried out using carrot (Daucus carota L.) as the test species. Three different concentrations, 0.25, 0.50, and 1 ppm were used to evaluate phytotoxicity of TCE. When added to petri plates with cotton pads, TCE did not have any effect on carrot seedling growth. However, when added to vermiculite, it significantly suppressed growth. Shoot growth was inhibited only at the 1 ppm concentration. Recovery experiments were carried out to study the fate of TCE in vermiculite. A significant decline in the percent recovery was observed with time. Interestingly, TCE additional peaks (unknown organic molecules) were detected with declining concentrations. The available chloride ion concentration in vermiculite containing 1 ppm of TCE for 24 hr was significantly higher compared to control. PMID:12918919

Inderjit; Asakawa, Chikako; Kakuta, Hideo

2003-06-01

368

Temperature dependent (37-15°C) anaerobic digestion of a trichloroethylene-contaminated wastewater.  

PubMed

The impact of a trichloroethylene (TCE) contaminated wastewater on the microbial community structure of an anaerobic granular biomass at 15°C compared to 37°C was investigated. Four expanded granular sludge bed (EGSB) bioreactors (R1-R4) were employed in pairs at 37 and 15°C. The influents of one of each pair were supplemented with increasing concentrations of TCE (max. 60 mgl(-1)). At 37°C, stable operation was maintained with 88% COD removal and >99% TCE removal at maximum influent TCE concentrations. R3 performance decreased at influent TCE concentration of 60 mgl(-1), although TCE removal rates of >97% were recorded. Archaeal community analysis via clone library and quantitative polymerase chain reaction (qPCR) analysis, and bacterial community analysis via denaturing gradient gel electrophoresis (DGGE), indicated that temperature resulted in a greater change in community structure than the presence of TCE, and clones related to cold adaptation of biomass were identified at 15°C. PMID:21715158

Siggins, Alma; Enright, Anne-Marie; O'Flaherty, Vincent

2011-09-01

369

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

2013-10-01

370

Physiologically Based Pharmacokinetic (PBPK) Modeling of Interstrain Variability in Trichloroethylene Metabolism in the Mouse  

PubMed Central

Background: Quantitative estimation of toxicokinetic variability in the human population is a persistent challenge in risk assessment of environmental chemicals. Traditionally, interindividual differences in the population are accounted for by default assumptions or, in rare cases, are based on human toxicokinetic data. Objectives: We evaluated the utility of genetically diverse mouse strains for estimating toxicokinetic population variability for risk assessment, using trichloroethylene (TCE) metabolism as a case study. Methods: We used data on oxidative and glutathione conjugation metabolism of TCE in 16 inbred and 1 hybrid mouse strains to calibrate and extend existing physiologically based pharmacokinetic (PBPK) models. We added one-compartment models for glutathione metabolites and a two-compartment model for dichloroacetic acid (DCA). We used a Bayesian population analysis of interstrain variability to quantify variability in TCE metabolism. Results: Concentration–time profiles for TCE metabolism to oxidative and glutathione conjugation metabolites varied across strains. Median predictions for the metabolic flux through oxidation were less variable (5-fold range) than that through glutathione conjugation (10-fold range). For oxidative metabolites, median predictions of trichloroacetic acid production were less variable (2-fold range) than DCA production (5-fold range), although the uncertainty bounds for DCA exceeded the predicted variability. Conclusions: Population PBPK modeling of genetically diverse mouse strains can provide useful quantitative estimates of toxicokinetic population variability. When extrapolated to lower doses more relevant to environmental exposures, mouse population-derived variability estimates for TCE metabolism closely matched population variability estimates previously derived from human toxicokinetic studies with TCE, highlighting the utility of mouse interstrain metabolism studies for addressing toxicokinetic variability. Citation: Chiu WA, Campbell JL Jr, Clewell HJ III, Zhou YH, Wright FA, Guyton KZ, Rusyn I. 2014. Physiologically based pharmacokinetic (PBPK) modeling of interstrain variability in trichloroethylene metabolism in the mouse. Environ Health Perspect 122:456–463;?http://dx.doi.org/10.1289/ehp.1307623

Campbell, Jerry L.; Clewell, Harvey J.; Zhou, Yi-Hui; Wright, Fred A.; Guyton, Kathryn Z.

2014-01-01

371

Uses of and exposure to trichloroethylene in U.S. industry: a systematic literature review.  

PubMed

This article describes a systematic review of the industrial hygiene literature for uses of trichloroethylene (TCE) in industry for the exposure assessment of two population-based case control studies of brain cancer in the United States. Papers and reports that address uses of and exposures to TCE were identified from MEDLINE, TOXLINE, NIOSHTIC, the NIOSH Health Hazard Evaluation database (keywords: chlorinated solvents and trichloroethylene), and in other reviews. This search was complemented by reviewing the reference lists from the identified literature. The collected information was systematized by the Standard Industrial Classification (SIC) system, and measurement data reported in the literature were summarized in a database. TCE use was extensive from the early 1920s through the 1970s mainly as a degreasing agent in metal-fabricating operations. After the 1970s it became less popular because of environmental concerns. TCE historically has had a multitude of uses in many other industries, e.g., dry cleaning, textile, electronics, leather, and rubber. Also, many products like adhesives, drugs, paints, inks, and various industrial products have contained TCE. It was banned as a food additive and in cosmetics in 1977. The arithmetic mean (AM) of the measurements across all industries and decades was 38.2 ppm. The highest personal and area air levels were reported in vapor degreasing (AM of 44.6 ppm). Most TCE measurements were performed in the 1950s, 1970s, and 1980s. The data described here could be used by exposure assessors as is to identify the presence and approximate levels of exposure. Using the same information as a basis should increase the reliability of the assessments, making it easier to compare both the exposure assessment methods and the epidemiologic results across different studies. PMID:17454505

Bakke, Berit; Stewart, Patricia A; Waters, Martha A

2007-05-01

372

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

373

Phototrophic utilization of toluene under anoxic conditions by a new strain of blastochloris sulfoviridis  

PubMed

The capacity of anoxygenic phototrophic bacteria to utilize aromatic hydrocarbons was investigated in enrichment cultures with toluene. When mineral medium with toluene (provided in an inert carrier phase) was inoculated with activated sludge and incubated under infrared illumination (> 750 nm), a red-to-brownish culture developed. Agar dilution series indicated the dominance of two types of phototrophic bacteria. One type formed red colonies, had rod-shaped cells with budding division, and grew on benzoate but not on toluene. The other type formed yellow-to-brown colonies, had oval cells, and utilized toluene and benzoate. One strain of the latter type, ToP1, was studied in detail. Sequence analysis of the 16S rRNA gene and DNA-DNA hybridization indicated an affiliation of strain ToP1 with the species Blastochloris sulfoviridis, a member of the alpha-subclass of Proteobacteria. However, the type strain (DSM 729) of Blc. sulfoviridis grew neither on toluene nor on benzoate. Light-dependent consumption of toluene in the presence of carbon dioxide and formation of cell mass by strain ToP1 were demonstrated in quantitative growth experiments. Strain ToP1 is the first phototrophic bacterium shown to utilize an aromatic hydrocarbon. In the supernatant of toluene-grown cultures and in cell-free extracts incubated with toluene and fumarate, the formation of benzylsuccinate was detected. These findings indicate that the phototrophic bacterium activates toluene anaerobically by the same mechanism that has been reported for denitrifying and sulfate-reducing bacteria. The natural abundance of phototrophic bacteria with the capacity for toluene utilization was examined in freshwater habitats. Counting series revealed that up to around 1% (1.8 x 10(5) cells per gram dry mass of sample) of the photoheterotrophic population cultivable with acetate grew on toluene. PMID:10525736

Zengler; Heider; Rossello-Mora; Widdel

1999-10-01

374

Anaerobic activation of toluene and o-xylene by addition to fumarate in denitrifying strain T.  

PubMed Central

Anaerobic assays conducted with strain T, a denitrifying bacterium capable of mineralizing toluene to carbon dioxide, demonstrated that toluene-grown, permeabilized cells catalyzed the addition of toluene to fumarate to form benzylsuccinate. This reaction was not dependent on the presence of coenzyme A (CoA) or ATP. In the presence of CoA, formation of E-phenylitaconate from benzylsuccinate was also observed. Kinetic studies demonstrated that the specific rate of benzylsuccinate formation from toluene and fumarate in assays with permeabilized cells was >30% of the specific rate of toluene consumption in whole-cell suspensions with nitrate; this observation suggests that benzylsuccinate formation may be the first reaction in anaerobic toluene degradation by strain T. Use of deuterium-labeled toluene and gas chromatography-mass spectrometry indicated that the H atom abstracted from the toluene methyl group during addition to fumarate was retained in the succinyl moiety of benzylsuccinate. In this study, no evidence was found to support previously proposed reactions of toluene with acetyl-CoA or succinyl-CoA. Toluene-grown, permeabilized cells of strain T also catalyzed the addition of o-xylene to fumarate to form (2-methylbenzyl)succinate. o-Xylene is not a growth substrate for strain T, and its transformation was probably cometabolic. With the exception of specific reaction rates, the observed characteristics of the toluene-fumarate addition reaction (i.e., retention of a methyl H atom and independence from CoA and ATP) also apply to the o-xylene-fumarate addition reaction. Thus, addition to fumarate may be a biochemical strategy to anaerobically activate a range of methylbenzenes.

Beller, H R; Spormann, A M

1997-01-01

375

Isolation and characterization of a novel toluene-degrading, sulfate-reducing bacterium.  

PubMed Central

A novel sulfate-reducing bacterium isolated from fuel-contaminated subsurface soil, strain PRTOL1, mineralizes toluene as the sole electron donor and carbon source under strictly anaerobic conditions. The mineralization of 80% of toluene carbon to CO2 was demonstrated in experiments with [ring-U-14C]toluene; 15% of toluene carbon was converted to biomass and nonvolatile metabolic by-products, primarily the former. The observed stoichiometric ratio of moles of sulfate consumed per mole of toluene consumed was consistent with the theoretical ratio for mineralization of toluene coupled with the reduction of sulfate to hydrogen sulfide. Strain PRTOL1 also transforms o- and p-xylene to metabolic products when grown with toluene. However, xylene transformation by PRTOL1 is slow relative to toluene degradation and cannot be sustained over time. Stable isotope-labeled substrates were used in conjunction with gas chromatography-mass spectrometry to investigate the by-products of toluene and xylene metabolism. The predominant by-products from toluene, o-xylene, and p-xylene were benzylsuccinic acid, (2-methylbenzyl)succinic acid, and 4-methylbenzoic acid (or p-toluic acid), respectively. Metabolic by-products accounted for nearly all of the o-xylene consumed. Enzyme assays indicated that acetyl coenzyme A oxidation proceeded via the carbon monoxide dehydrogenase pathway. Compared with the only other reported toluene-degrading, sulfate-reducing bacterium, strain PRTOL1 is distinct in that it has a novel 16S rRNA gene sequence and was derived from a freshwater rather than marine environment.

Beller, H R; Spormann, A M; Sharma, P K; Cole, J R; Reinhard, M

1996-01-01

376

Hydrotreating of wheat straw in toluene and ethanol.  

PubMed

In the present work, wheat straw was hydroliquefied at a temperature of 300°C for 4h in ethanol or toluene in order to obtain bio-components which are useful for fuel purposes. The experiments were performed in a 100mL batch reactor under hydrogen pressure of 70bar. Typically, 2g of straw and 0.1g of catalyst (66%Ni/SiO2-Al2O3) were dispersed in 15g of solvent. The main compounds of the oil produced during the liquefaction of hemicellulose, cellulose and lignin of wheat straw in both solvents are: tetrahydrofuran-2-methanol, 1,2-butanediol and butyrolactone. Besides the mentioned compounds, ethanol favoured the decomposition of bigger molecules to short-chain alcohols such as 1-butanol, 1,2-propanediol and 1,2-ethanediol. Toluene contributes to the production of furans and other cyclic compounds. The light fractions distilled together with the solvent also contain the following: 1-propanol, 2-methyl-cyclopentanone, acetic acid and ethyl acetate. PMID:24787323

Murnieks, Raimonds; Kampars, Valdis; Malins, Kristaps; Apseniece, Lauma

2014-07-01

377

Measurements of benzene, toluene and xylenes in urban air  

NASA Astrophysics Data System (ADS)

Results from measurements of benzene, toluene and xylenes in the city centre of Oslo are presented. The samples were collected in March and August/September 1980 at two of the stations used in an air pollution monitoring program. One was in a street canyon station and the other was a reference station. The sampling equipment was two charcoal filters in series, placed in a filter holder with a disk of glass fibre prefilter in front. Analysis was by high resolution gas chromatography. The single measured separate values of these aromatics ranged from 1 to 210?m -3. Benzene concentrations especially ranged from 4 to 114 ?g m -3. The concentrations of benzene and toluene seemed to be higher in August/September than in March, while the concentrations of the xylenes seemed to be about the same. The variations in concentrations of the aromatics follow each other closely in both measuring periods which indicates that all components are emitted from the same sources and are dispersed in the same way. Correlation between benzene and CO and between benzene and ambient temperature are discussed.

Wathne, Bente M.

378

Biotransformation of nitrobenzene by bacteria containing toluene degradative pathways  

SciTech Connect

Nonpolar nitroaromatic compounds have been considered resistant to attack by oxygenases because of the electron withdrawing properties of the nitro group. The authors have investigate the ability of seven bacterial strains containing toluene degradative pathways to oxidize nitrobenzene. Cultures were induced with toluene vapor prior to incubation with nitrobenzene, and products were identified by high-performance liquid chromatography and gas chromatography-mass spectrometry. Pseudomonas cepacia G4 and a strain of Pseudomonas harboring the TOL plasmid (pTN2) did not transform nitrobenzene. Cells of Pseudomonas putida F1 and Pseudomonas sp. strain JS150 converted nitrobenzene to 3-nitrocatechol. Transformation of nitrobenzene in the presence of {sup 18}O{sub 2} indicated that the reaction in JS150 involved the incorporation of both atoms of oxygen in the 3-nitrocatechol, which suggests a dioxygenase mechanism. P. putida 39/D, a mutant strain of P. putida F1, converted nitrobenzene to a compound tentatively identified as cis-1, 2-dihydroxy-3-nitrocyclohexa-3, 5-diene. This compound was rapidly converted to 3-nitrocatechol by cells of strain JS150. Cultures of Pseudomonas mendocina KR-1 converted nitrobenzene to a mixture of 3- and 4-nitrophenol (10 and 63%, respectively). Pseudomonas pickettii PKO1 converted nitrobenzene to 3- and 4-nitrocatechol via 3- and 4-nitrophenol. The nitrocatechols were slowly degraded to unidentified metabolites. Nitrobenzene did not serve as an inducer for the enzymes that catalyzed its oxidation.

Haigler, B.E.; Spain, J.C. (Air Force Civil Engineering Support Agency, Tyndall AFB, FL (United States))

1991-11-01

379

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

380

Occurrence of mental illness following prenatal and early childhood exposure to tetrachloroethylene (PCE)-contaminated drinking water: a retrospective cohort study  

PubMed Central

Background While many studies of adults with solvent exposure have shown increased risks of anxiety and depressive disorders, there is little information on the impact of prenatal and early childhood exposure on the subsequent risk of mental illness. This retrospective cohort study examined whether early life exposure to tetrachloroethylene (PCE)-contaminated drinking water influenced the occurrence of depression, bipolar disorder, post-traumatic stress disorder, and schizophrenia among adults from Cape Cod, Massachusetts. Methods A total of 1,512 subjects born between 1969 and 1983 were studied, including 831 subjects with both prenatal and early childhood PCE exposure and 547 unexposed subjects. Participants completed questionnaires to gather information on mental illnesses, demographic and medical characteristics, other sources of solvent exposure, and residences from birth through 1990. PCE exposure originating from the vinyl-liner of water distribution pipes was assessed using water distribution system modeling software that incorporated a leaching and transport algorithm. Results No meaningful increases in risk ratios (RR) for depression were observed among subjects with prenatal and early childhood exposure (RR: 1.1, 95% CI: 0.9-1.4). However, subjects with prenatal and early childhood exposure had a 1.8-fold increased risk of bipolar disorder (N = 36 exposed cases, 95% CI: 0.9-1.4), a 1.5-fold increased risk post-traumatic stress disorder (N = 47 exposed cases, 95% CI: 0.9-2.5), and a 2.1-fold increased risk of schizophrenia (N = 3 exposed cases, 95% CI: 0.2-20.0). Further increases in the risk ratio were observed for bipolar disorder (N = 18 exposed cases, RR; 2.7, 95% CI: 1.3-5.6) and post-traumatic stress disorder (N = 18 exposed cases, RR: 1.7, 95% CI: 0.9-3.2) among subjects with the highest exposure levels. Conclusions The results of this study provide evidence against an impact of early life exposure to PCE on the risk of depression. In contrast, the results provide support for an impact of early life exposure on the risk of bipolar disorder and post-traumatic stress disorder. The number of schizophrenia cases was too small to draw reliable conclusions. These findings should be confirmed in investigations of other similarly exposed populations.

2012-01-01

381

Risk of breast cancer following exposure to tetrachloroethylene-contaminated drinking water in Cape Cod, Massachusetts: reanalysis of a case-control study using a modified exposure assessment  

PubMed Central

Background Tetrachloroethylene (PCE) is an important occupational chemical used in metal degreasing and drycleaning and a prevalent drinking water contaminant. Exposure often occurs with other chemicals but it occurred alone in a pattern that reduced the likelihood of confounding in a unique scenario on Cape Cod, Massachusetts. We previously found a small to moderate increased risk of breast cancer among women with the highest exposures using a simple exposure model. We have taken advantage of technical improvements in publically available software to incorporate a more sophisticated determination of water flow and direction to see if previous results were robust to more accurate exposure assessment. Methods The current analysis used PCE exposure estimates generated with the addition of water distribution modeling software (EPANET 2.0) to test model assumptions, compare exposure distributions to prior methods, and re-examine the risk of breast cancer. In addition, we applied data smoothing to examine nonlinear relationships between breast cancer and exposure. We also compared a set of measured PCE concentrations in water samples collected in 1980 to modeled estimates. Results Thirty-nine percent of individuals considered unexposed in prior epidemiological analyses were considered exposed using the current method, but mostly at low exposure levels. As a result, the exposure distribution was shifted downward resulting in a lower value for the 90th percentile, the definition of "high exposure" in prior analyses. The current analyses confirmed a modest increase in the risk of breast cancer for women with high PCE exposure levels defined by either the 90th percentile (adjusted ORs 1.0-1.5 for 0-19 year latency assumptions) or smoothing analysis cut point (adjusted ORs 1.3-2.0 for 0-15 year latency assumptions). Current exposure estimates had a higher correlation with PCE concentrations in water samples (Spearman correlation coefficient = 0.65, p < 0.0001) than estimates generated using the prior method (0.54, p < 0.0001). Conclusions The incorporation of sophisticated flow estimates in the exposure assessment method shifted the PCE exposure distribution downward, but did not meaningfully affect the exposure ranking of subjects or the strength of the association with the risk of breast cancer found in earlier analyses. Thus, the current analyses show a slightly elevated breast cancer risk for highly exposed women, with strengthened exposure assessment and minimization of misclassification by using the latest technology.

2011-01-01

382

Vapor-liquid equilibria in toluene + m-Xylene, toluene + n-decane, and n-deane + m-xylene mixtures  

SciTech Connect

Isothermal vapor-liquid equilibria at three temperatures between 373.5 and 394.3 K were measured for the binary systems toluene + m-xylene, toluene + n-decane, and n-decane + m-xylene by using a recirculating still. The data reported were found to be thermodynamically consistent and were correlated with four well-known activity coefficient models. The maximum likelihood method was used to estimate the parameters of the models.

Willman, B.; Teja, A.S.

1985-01-01

383

Trichloroethylene Induces Methylation of the Serca2 Promoter in H9c2 Cells and Embryonic Heart  

Microsoft Academic Search

Trichloroethylene (TCE) is a halogenated hydrocarbon used as a solvent in industrial settings and in house-cleaning products.\\u000a Exposure to TCE has been linked to increased risk for congenital heart malformations in both human and animal models. Previous\\u000a studies showed TCE exposure reduced the expression and function of the ATP-dependent calcium pump, Serca2a, which is important for regulating calcium flux in

Brittany Palbykin; Jamie Borg; Patricia T. Caldwell; Josh Rowles; Andreas J. Papoutsis; Donato F. Romagnolo; Ornella I. Selmin

2011-01-01

384

Degradation of trichloroethylene and trans-1,2-dichloroethylene by a methanotrophic consortia in a trickle-type bioreactor  

SciTech Connect

A trickle-bed bioreactor containing a consortium of microorganisms utilizing methane as the primary carbon source was used to treat a synthetic groundwater containing trichloroethylene (TCE) and trans-1, 2-dichloroethylene (DCE). With influent concentrations of TCE and DCE of 1 mg/L each and an average residence time of about 50 min, >50% of the TCE and >90% of the DCE was degraded. The reactor exhibited first-order kinetics with respect to TCE degradation. 5 refs., 1 tab.

Strandberg, G.W.; Donaldson, T.L.; Bolla, L.L.; Palumbo, A.V.; Eng, W.

1988-01-01

385

Deposition of Fe–Ni nanoparticles on Al 2O 3 for dechlorination of chloroform and trichloroethylene  

Microsoft Academic Search

This research proposes an efficient method for depositing Fe–Ni nanoparticles on Al2O3 microparticles to decompose containments in ground water, such as chloroform and trichloroethylene. The Fe–Ni nanoparticles can be deposited onto the surface of Al2O3 microparticles by electroless plating technique. The reasons why the Fe–Ni nanoparticles would be deposited on the surface of Al2O3 microparticles is to avoid the agglomeration

Shu-Huei Hsieh; Jao-Jia Horng

2006-01-01

386

Research note Dissolution of a well-defined trichloroethylene pool in saturated porous media: experimental results and model simulations  

Microsoft Academic Search

An experimental mass transfer correlation was developed for trichloroethylene (TCE) pools dissolving in water- saturated porous media. A three-dimensional, bench-scale model aquifer previously designed by Chrysikopoulos et al. (Water Resour. Res. 36(7) (2000) 1687) was employed for collection of the experimental dissolution data. The unique aspect of the model aquifer design is the formation of a well-defined, circular TCE pool

Kenneth Y. Lee; Constantinos V. Chrysikopoulos

387

Photocatalytic degradation of phenol and trichloroethylene: On-line and real-time monitoring via membrane introduction mass spectrometry  

Microsoft Academic Search

Membrane introduction mass spectrometry (MIMS) has been applied to monitor and compare in real time the extent by which three photocatalytic remediation processes--Fenton`s reagent\\/UV, ferrioxalate\\/HâOâ\\/UV, and TiOâ\\/UV--destroy two common water pollutants--phenol and trichloroethylene (TCE). Continuous MIMs and selected ion monitoring (MIMS-SIM) of both phenol and TCE degradation and COâ production show first-order kinetics for the three processes. Phenol half-life times

R. F. P. Nogueria; Rosana M. Alberici; Maria Anita Mendes; Wilson F. Jardim; Marcos N. Eberlin

1999-01-01

388

The Extent of Dichloroacetate Formation from Trichloroethylene, Chloral Hydrate, Trichloroacetate, and Trichloroethanol in B6C3F1 Mice  

Microsoft Academic Search

Conflicting data have been published related to the formation of dichloroacetate (DCA) from trichloroethylene (TRI), chloral hydrate (CH), or trichloroacetic acid (TCA) in B6C3F1 mice. TCA is usually indicated as the primary metabolic precursor to DCA. Model simulations based on the known pharmacokinetics of TCA and DCA predicted blood concentrations of DCA that were 10- to 100-fold lower than previously

J. L. Merdink; A. Gonzalez-Leon; R. J. Bull; I. R. Schultzt

1998-01-01

389

Unique Kinetic Properties of Phenol-Degrading Variovorax Strains Responsible for Efficient Trichloroethylene Degradation in a Chemostat Enrichment Culture  

Microsoft Academic Search

A chemostat enrichment of soil bacteria growing on phenol as the sole carbon source has been shown to exhibit quite high trichloroethylene (TCE)-degrading activities (H. Futamata, S. Harayama, and K. Watanabe, Appl. Environ. Microbiol. 67:4671-4677, 2001). To identify the bacterial populations responsible for the high TCE-degrading activity, a multidisciplinary survey of the chemostat enrichment was conducted by employing molecular-ecological and

Hiroyuki Futamata; Yayoi Nagano; Kazuya Watanabe; Akira Hiraishi

2005-01-01

390

Thermally Activated Persulfate Oxidation of Trichloroethylene (TCE) and 1,1,1Trichloroethane (TCA) in Aqueous Systems and Soil Slurries  

Microsoft Academic Search

Under thermally activated conditions (i.e., temperature of 40?99°C), there is considerable evidence that the persulfate anion () can be converted to a powerful oxidant known as the sulfate free radical (), which could be used in situ to destroy groundwater contaminants. In this laboratory study only limited trichloroethylene (TCE) degradation and no 1,1,1-trichloroethane (TCA) degradation was observed at 20°C. However,

Chen Ju Liang; Clifford J. Bruell; Michael C. Marley; Kenneth L. Sperry

2003-01-01

391

EVALUATING MOLECULAR SITES OF ACTION FOR TOLUENE USING AN IN VIVO MODEL.  

EPA Science Inventory

In vitro studies have demonstrated that toluene disrupts the function of several ion channels localized in the brain, including the NMDA-glutamate receptor. This has led to the hypothesis that effects on ion channel function may contribute to toluene neurotoxicity, CNS depres...

392

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 VOC?s is the potential for persistent neurotoxic effects from long term e...

393

Transformation of pWWO in Rhizobium leguminosarum DPT to Engineer Toluene Degrading Ability for Rhizoremediation.  

PubMed

Rhizoremediation of organic xenobiotics is based on interactions between plants and their associated micro-organisms. The present work was designed to engineer a bacterial system having toluene degradation ability along with plant growth promoting characteristics for effective rhizoremediation. pWWO harboring the genes responsible for toluene breakdown was isolated from Pseudomonas putida MTCC 979 and successfully transformed in Rhizobium DPT. This resulted in a bacterial strain (DPT(T)) which had the ability to degrade toluene as well as enhance growth of host plant. The frequency of transformation was recorded 5.7 × 10(-6). DPT produced IAA, siderophore, chitinase, HCN, ACC deaminase, solubilized inorganic phosphate, fixed atmospheric nitrogen and inhibited the growth of Fusarium oxysporum and Macrophomina phaseolina in vitro. During pot assay, 50 ppm toluene in soil was found to inhibit the germination of Cajanus cajan seeds. However when the seeds bacterized with toluene degrading P. putida or R. leguminosarum DPT were sown in pots, again no germination was observed. Non-bacterized as well as bacterized seeds germinated successfully in toluene free soil as control. The results forced for an alternative mode of application of bacteria for rhizoremediation purpose. Hence bacterial suspension was mixed with soil having 50 ppm of toluene. Germination index in DPT treated soil was 100% while in P. putida it was 50%. Untreated soil with toluene restricted the seeds to germinate. PMID:23729882

Goel, Garima; Pandey, Piyush; Sood, Anchal; Bisht, Sandeep; Maheshwari, D K; Sharma, G D

2012-06-01

394

Health risk assessment and applied action level of toluene. Final report  

SciTech Connect

The purpose of the document is to provide information on the toxicity of toluene and to estimate Applied Action Levels (AALs) for toluene in water, air, and soil. The information provided will aid the California Dept. of Health Services manage hazardous waste sites and protect the health of California residents.

Reed, N.R.; Reed, W.A.; Weir, K.; Encomienda, I.; Beltran, L.M.

1989-05-16

395

Reduction of solvent content in toluene–neoprene adhesives and in acetone–polyurethane adhesives  

Microsoft Academic Search

The desorption of toluene in a polychloroprene (neoprene)-toluene adhesive and in a commercial neoprene adhesive was studied in air at three different temperatures by monitoring the weight loss vs time. Similarly, the desorption of acetone in a polyurethane adhesive and in a commercial adhesive was also considered. The experimental weight variations are correlated with the solution of the second Fick

M. C. Sabater; M. A. Martínez

2001-01-01

396

Kinetics of Toluene-Induced Leakage of Low Molecular Weight Solutes from Excised Sorghum Tissues 1  

PubMed Central

The relationship between toluene concentration and the rate of leakage of solutes from toluene-treated roots and leaves of Sorghum bicolor, L. Moench, was studied to determine the effect of toluene on plant cell membranes. A threshold concentration of 0.2% toluene was needed to induce leakage. Maximal leakage rates were obtained with 0.5% toluene. Low molecular weight solutes, such as amino acids, sugars, and inorganic ions, leaked from treated tissue, while macromolecules, such as protein were retained. The rates at which the low molecular weight solutes diffused from treated cells decreased with increasing molecular weight. At 25°C, treatment of roots and leaves with 0.5% toluene resulted in the quasi-quantitative leakage of solutes within 180 minutes. At 1°C, roots and leaves differed in their response to toluene. The rates of leakage from roots at 1°C were much lower and the total amounts much smaller than at 25°C, while in leaves the difference between the two temperatures was very small. The procedure of treating tissues with 0.5% toluene for 180 minutes at 25°C proved to be a rapid and simple technique for quantitative extraction of water-soluble, low molecular weight solutes from plant cells into the extracting medium while macromolecular constituents are retained inside the cells.

Weimberg, Ralph; Lerner, H. R.; Poljakoff-Mayber, A.

1981-01-01

397

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...

398

Study of the corrosion resistance of metals in the media of phenol synthesis from toluene  

Microsoft Academic Search

Phenol is obtained from toluene in two stages. The toluene is first oxidized to benzoic acid in the presence of soluble cobalt and manganese salts. The obtained benzoic acid is then subjected to oxidizing decarboxylation in the presence of soluble copper and magnesium salts. Oxidizing decarboxylation of the benzoic acid is conducted with the simultaneous treatment of the reacting mass

Yu. I. Perin; R. A. Valieva; A. A. Sokolov

1967-01-01

399

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

400

Synchrotron x-ray microtomography, electron probe microanalysis, and nmr of toluene waste in cement.  

National Technical Information Service (NTIS)

Synchrotron X-ray microtomography shows vesicular structures for toluene/cement mixtures, prepared with 1.22 to 31.58 wt% toluene. Three-dimensional imaging of the cured samples shows spherical vesicles, with diameters ranging from 20 to 250 pm; a search ...

Butler

1999-01-01

401

Toluene decreases Purkinje cell output by enhancing inhibitory synaptic transmission in the cerebellar cortex.  

PubMed

Toluene belongs to a class of psychoactive drugs known as inhalants. Found in common household products such as adhesives, paint products, and aerosols, toluene is inhaled for its intoxicating and euphoric properties. Additionally, exposure to toluene disrupts motor behaviors in a manner consistent with impairments to cerebellar function. Previous work has suggested a role of GABA in mediating toluene's neurobehavioral effects, but how this manifests in the cerebellar cortex is not yet understood. In the present study, we examined the effects of toluene on cerebellar Purkinje cell action potential output and inhibitory synaptic transmission onto Purkinje cells using patch clamp electrophysiology in acute rat cerebellar slices. Toluene (1mM) reduced the frequency of Purkinje cell action potential output without affecting input resistance. Furthermore, toluene dose-dependently enhanced inhibitory synaptic transmission onto Purkinje cells, increasing the amplitude and frequency of inhibitory postsynaptic currents; no change in the frequency of action potentials from molecular layer interneurons was noted. The observed decreases in Purkinje cell action potential output could contribute to toluene-evoked impairments in cerebellar and motor functions. PMID:24345417

Gmaz, Jimmie M; McKay, Bruce E

2014-02-01

402

Autoignition of toluene reference fuels at high pressures modeled with detailed chemical kinetics  

Microsoft Academic Search

A detailed chemical kinetic model for the autoignition of toluene reference fuels (TRF) is presented. The toluene submechanism added to the Lawrence Livermore Primary Reference Fuel (PRF) mechanism was developed using recent shock tube autoignition delay time data under conditions relevant to HCCI combustion. For two-component fuels the model was validated against recent high-pressure shock tube autoignition delay time data

J. C. G. Andrae; P. Björnbom; R. F. Cracknell; G. T. Kalghatgi

2007-01-01

403

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 ...

404

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

405

Are biogenic emissions a significant source of summertime atmospheric toluene in rural Northeastern United States?  

Microsoft Academic Search

Summertime atmospheric toluene enhancements at Thompson Farm in the rural northeastern United States were unexpected and resulted in a toluene\\/benzene seasonal pattern that was distinctly different from that of other anthropogenic volatile organic compounds. Consequentially, three hydrocarbon sources were investigated for potential contributions to the enhancements during 2004 2006. These included: 1) increased warm season fuel evaporation coupled with changes

M. L. White; R. S. Russo; Y. Zhou; J. L. Ambrose; K. Haase; E. K. Frinak; R. K. Varner; O. W. Wingenter; H. Mao; R. Talbot; B. C. Sive

2008-01-01

406

Are biogenic emissions a significant source of summertime atmospheric toluene in the rural Northeastern United States?  

Microsoft Academic Search

Summertime atmospheric toluene enhancements at Thompson Farm in the rural northeastern United States were unexpected and resulted in a toluene\\/benzene seasonal pattern that was distinctly different from that of other anthropogenic volatile organic compounds. Consequently, three hydrocarbon sources were investigated for potential contributions to the enhancements during 2004-2006. These included: (1) increased warm season fuel evaporation coupled with changes in

M. L. White; R. S. Russo; Y. Zhou; J. L. Ambrose; K. Haase; E. K. Frinak; R. K. Varner; O. W. Wingenter; H. Mao; R. Talbot; B. C. Sive

2009-01-01

407

Low-temperature anaerobic biological treatment of toluene-containing wastewater.  

PubMed

Two expanded granular sludge bed-anaerobic filter (EGSB-AF) bioreactors, R1 and R2, were operated at 15 degrees C for the treatment of toluene-contaminated volatile fatty acid-based wastewater. The seed inoculum and the R1 reactor were unexposed to toluene, prior to and during the trial, respectively. Both reactors were operated at a hydraulic retention time of 24h at applied organic loading rates of 0.71-1.43kg chemical oxygen demand (COD)m(-3)d(-1). Toluene was supplemented to the R2 influent at concentrations of 5-104 mg toluenel(-1) (solubilised in ethanol). Bioreactor performance was evaluated by COD and toluene removal efficiency, and the methane content of biogas (%). Specific methanogenic activity and toxicity assays were employed to investigate the activity and toluene toxicity thresholds of key trophic groups, respectively, within the seed and reactor biomass samples. COD and toluene removal efficiencies of 70-90% and 55-99%, respectively, were achieved during the 630-d trial. Metabolic assays suggested that a psychrotolerant H(2)/CO(2)-utilizing methanogenic community developed in the toluene-degrading biomass. The results indicate the viability of low-temperature anaerobic digestion for the treatment of wastewater containing toluene. PMID:17306857

Enright, Anne-Marie; Collins, Gavin; O'Flaherty, Vincent

2007-04-01

408

Effects of activated carbon fibre-supported metal oxide characteristics on toluene removal.  

PubMed

Few studies have investigated the use of activated carbon fibres (ACFs) impregnated with metal oxides for the catalytic oxidation of volatile organic compounds (VOCs). Thus, the effects of the ACF-supported metal oxides on toluene removal are determined in this study. Three catalysts, namely, Ce, Mn, and Cu, two pretreatment solutions NaOH and H2O2, and three reaction temperatures of 250 degrees C, 300 degrees C, and 350 degrees C, were employed to determine toluene removal. The composition and morphology of the catalysts were analysed using Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectrometer (FTIR), and thermo-gravimetric analyser (TGA) to study the effects of the catalyst's characteristics on toluene removal. The results demonstrated that the metal catalysts supported on the ACFs could significantly increase toluene removal. The Mn/ACFs and Cu/ACFs were observed to be most active in toluene removal at a reaction temperature of 250 degrees C with 10% oxygen content. Moreover, the data also indicated that toluene removal was slightly improved after pretreating the ACFs with NaOH and H2O2. The results suggested that surface-metal loading and the surface characteristics of the ACFs were the determinant parameters for toluene removal. Furthermore, the removal of toluene over Mn/ACFs-H202 decreased when the reaction temperature considered was > 300 degrees C. PMID:24701949

Liu, Zhen-Shu; Peng, Yu-Hui; Li, Wen-Kai

2014-01-01

409

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

410

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

411

Soot formation during combustion of unsupported methanol/toluene mixture droplets in microgravity  

NASA Technical Reports Server (NTRS)

Results are reported of an experimental study tracing the influence of liquid composition on soot formation and the burning rate of a droplet composed of a binary miscible mixture of liquids. The mixture components represented a highly sooting fuel, toluene, and a nonsooting fuel, methanol. The toluene concentration in methanol was shown to dramatically influence flame luminosity and soot production. Neither burning rates nor a propensity for flame extinction appeared to be significantly affected by toluene mixture fractions. Five-percent toluene mixture droplets behaved like pure methanol droplets in terms of burning rate, lack of flame luminosity, and extinction. Increasing the toluene concentration in the droplets to 25 percent increased flame luminosity, yet no visible soot agglomerates were observed. The 50-percent-mixture droplets burned with highly luminous flames and large amounts of soot agglomerates collecting inside the flame. All the mixture droplets showed burning rates similar to those of pure methanol and likewise exhibited flame extinction before complete droplet vaporization.

Jackson, G. S.; Avedisian, C. T.; Yang, J. C.

1991-01-01

412

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

413

Toluene PBPK Models to Extrapolate Neurological Effects between Rats and Humans, Across Acute Durations and Severity Categories  

EPA Science Inventory

Acute exposure to volatile organic compounds including toluene and ethanol impairs neurological function. Dose-response relationships have been used to quantify the degree of impairment using a variety of behavioral tasks including reaction time. Brain toluene concentrations (Br-...

414

Toluene PBPK Models to Extrapolate Neurological Effects between Rats and Humans, Across Acute Durations and Across Severity Categories  

EPA Science Inventory

Acute exposure to volatile organic compounds including toluene and ethanol impairs neurological function. Dose-response relationships have been used to quantify the degree of impairment using a variety of behavioral tasks including reaction time. Brain toluene concentrations (Br-...

415

DETERMINATION OF SECONDARY ORGANIC AEROSOL PRODUCTS FROM THE PHOTOOXIDATION OF TOLUENE AND THEIR IMPLICATIONS IN AMBIENT PM2.5  

EPA Science Inventory

Laboratory study was carried out to investigate the secondary organic aerosol products from photooxidation of the aromatic hydrocarbon toluene. The laboratory experiments consisted of irradiating toluene/propylene/NOX/air mixtures in a smog chamber operated in the dynamic mode...

416

Differential Effects of Inhaled Toluene on Locomotor Activity in Adolescent and Adult Rats  

PubMed Central

Inhalant abuse is a world-wide public health concern among adolescents. Most preclinical studies have assessed inhalant effects in adult animals leaving unclear how behavioral effects differ in younger animals. We exposed adolescent (postnatal day [PN] 28) and adult (PN90) male rats to toluene using 1 of 3 exposure patterns. These patterns modeled those reported in toluene abuse in teens and varied concentration, number and length of exposures, as well as the inter-exposure interval. Animals were exposed repeatedly over 12 days to toluene concentrations of 0, 8,000 or 16,000 parts per million (ppm). Locomotor activity was quantified during toluene exposures and for 30 min following completion of the final daily toluene exposure. For each exposure pattern, there were significant toluene concentration-related increases and decreases in locomotor activity compared to the 0-ppm “air” controls at both ages. These changes depended upon when activity was measured – during or following exposure. Compared to adults, adolescents displayed greater locomotor activity on the first day and generally greater increases in activity over days than adults during toluene exposure. Adults displayed greater locomotor activity than adolescents in the “recovery” period following exposure on the first and subsequent days. Age group differences were clearest following the pattern of paced, brief (5-min) repeated binge exposures. The results suggest that locomotor behavior in rats during and following inhalation of high concentrations of toluene depends on age and the pattern of exposure. The results are consistent with dose-dependent shifts in sensitivity and sensitization or tolerance to repeated toluene in the adolescent animals compared to the adult animals. Alternate interpretations are possible and our interpretation is limited by the range of very high concentrations of toluene used. The results imply that both pharmacological and psychosocial factors contribute to the teen prevalence of inhalant abuse.

Batis, Jeffery C.; Hannigan, John H.; Bowen, Scott E.

2010-01-01

417

Kinetics of competitive inhibition and cometabolism in the biodegradation of benzene, toluene, and p-xylene by two Pseudomonas isolates  

Microsoft Academic Search

Two Pseudomonas species (designated strains B1 and X1) were isolated from an aerobic pilot-scale fluidized-bed reactor treating groundwater containing benzene, toluene, and p-xylene (BTX). Strain B1 grew with benzene and toluene as the sole sources of carbon and energy, and it cometabolized p-xylene in the presence of toluene. Strain X1 grew on toluene and p-xylene, but not benzene. In single

Myungkeun Chang; T. C. Voice; C. S. Criddle

1993-01-01

418

Characterization of carbon supported molybdenum sulfide catalysts using toluene chemisorption  

SciTech Connect

The commercial application of molybdenum-based catalysts for hydrodesulfurization and hydrodenitrogenation, which are invariably accompanied by hydrogenation, has been practiced for several decades. However, the extent of dispersion of the metal species on the catalyst support is usually not measured, since these catalysts are not amenable to conventional characterization techniques such as X-ray diffraction line broadening and electron microscopy, especially for metal loadings less than 10-15% wt. The adsorption of aromatic molecules on supported molybdenum and molybdenum-based sulfide catalysts as a tool for ascertaining metal dispersion is not well-documented even though the hydrocarbon liquids which are processed with these catalysts contain high proportions of aromatic compounds. In the work reported here, chemisorption of toluene (an aromatic hydrocarbon) was used as a probe to measure qualitatively the dispersion of molybdenum on a carbon support. The catalysts were of the type shown previously to have high activities for hydrogenation of coal asphaltenes.

Scaroni, A.W.; Abotsi, G.M.K.; Derbyshire, F.J. (Pennsylvania State Univ., University Park (USA))

1987-04-01

419

Kinetics and mechanism of Moroccan oil shale solubilization in toluene  

SciTech Connect

Unlike coal, for which solvent liquefaction dates back to the beginning of this century, treatment of oil shale using various solvents has received attention only in recent years as an alternative process to producing liquid fuels by retorting. Solvent extraction offers the promise of overcoming the relatively low yields of desirable products obtained and the high energy expenditures required in pyrolysis. The present study was undertaken to investigate the solubilization of a Moroccan oil shale at 300{degree}C and 3000 psig in toluene. In this case the extent of solubilization was measured in terms of tetrahydrofuran extractables at refluxing conditions. Analyses of the soluble material produced were obtained by gel permeation chromatography and proton NMR since these provide valuable information for mechanistic interpretations.

Tahiri, M.; Sliepcevich, C.M.; Mallinson, R.G.

1987-04-01

420

Microbial degradation of toluene under sulfate-reducing conditions and the influence of iron on the process.  

PubMed

Toluene degradation occurred concomitantly with sulfate reduction in anaerobic microcosms inoculated with contaminated subsurface soil from an aviation fuel storage facility near the Patuxent River (Md.). Similar results were obtained for enrichment cultures in which toluene was the sole carbon source. Several lines of evidence suggest that toluene degradation was directly coupled to sulfate reduction in Patuxent River microcosms and enrichment cultures: (i) the two processes were synchronous and highly correlated, (ii) the observed stoichiometric ratios of moles of sulfate consumed per mole of toluene consumed were consistent with the theoretical ratio for the oxidation of toluene to CO2 coupled with the reduction of sulfate to hydrogen sulfide, and (iii) toluene degradation ceased when sulfate was depleted, and conversely, sulfate reduction ceased when toluene was depleted. Mineralization of toluene was confirmed in experiments with [ring-U-14C]toluene. The addition of millimolar concentrations of amorphous Fe(OH)3 to Patuxent River microcosms and enrichment cultures either greatly facilitated the onset of toluene degradation or accelerated the rate once degradation had begun. In iron-amended microcosms and enrichment cultures, ferric iron reduction proceeded concurrently with toluene degradation and sulfate reduction. Stoichiometric data and other observations indicate that ferric iron reduction was not directly coupled to toluene oxidation but was a secondary, presumably abiotic, reaction between ferric iron and biogenic hydrogen sulfide. PMID:1575481

Beller, H R; Grbi?-Gali?, D; Reinhard, M

1992-03-01

421

Microbial degradation of toluene under sulfate-reducing conditions and the influence of iron on the process  

Microsoft Academic Search

Toluene degradation occurred concomitantly with sulfate reduction in anaerobic microcosms inoculated with contaminated subsurface soil from an aviation fuel storage facility near the Patuxent River (Md.). Similar results were obtained from enrichment cultures in which toluene was the sole carbon source. Several lines of evidence suggest that toluene degradation was directly coupled to sulfate reduction in Patuxent River microcosms and

H. R. Beller; D. Grbic-Galic; M. Reinhard

1992-01-01

422

Microbial degradation of toluene under sulfate-reducing conditions and the influence of iron on the process  

Microsoft Academic Search

Toluene degradation occurred concomitantly with sulfate reduction in anaerobic microcosms inoculated with contaminated subsurface soil from an aviation fuel storage facility near the Patuxent River (Md.). Similar results were obtained for enrichment cultures in which toluene was the sole carbon source. Several lines of evidence suggest that toluene degradation was directly coupled to sulfate reduction in Patuxent River microcosms and

H. R. Beller; D. Grbic-Galic; M. Reinhard

1992-01-01

423

Microbial degradation of toluene under sulfate-reducing conditions and the influence of iron on the process.  

PubMed Central

Toluene degradation occurred concomitantly with sulfate reduction in anaerobic microcosms inoculated with contaminated subsurface soil from an aviation fuel storage facility near the Patuxent River (Md.). Similar results were obtained for enrichment cultures in which toluene was the sole carbon source. Several lines of evidence suggest that toluene degradation was directly coupled to sulfate reduction in Patuxent River microcosms and enrichment cultures: (i) the two processes were synchronous and highly correlated, (ii) the observed stoichiometric ratios of moles of sulfate consumed per mole of toluene consumed were consistent with the theoretical ratio for the oxidation of toluene to CO2 coupled with the reduction of sulfate to hydrogen sulfide, and (iii) toluene degradation ceased when sulfate was depleted, and conversely, sulfate reduction ceased when toluene was depleted. Mineralization of toluene was confirmed in experiments with [ring-U-14C]toluene. The addition of millimolar concentrations of amorphous Fe(OH)3 to Patuxent River microcosms and enrichment cultures either greatly facilitated the onset of toluene degradation or accelerated the rate once degradation had begun. In iron-amended microcosms and enrichment cultures, ferric iron reduction proceeded concurrently with toluene degradation and sulfate reduction. Stoichiometric data and other observations indicate that ferric iron reduction was not directly coupled to toluene oxidation but was a secondary, presumably abiotic, reaction between ferric iron and biogenic hydrogen sulfide.

Beller, H R; Grbic-Galic, D; Reinhard, M

1992-01-01

424

Vapour-liquid equilibrium relationship between toluene and mixed surfactants.  

PubMed

Micellar partitioning of volatile organic compounds (VOCs) in surfactant solutions and its effects on vapour-liquid equilibrium is fundamental to the overall design and implementation ofsurfactant-enhanced remediation. Knowledge of the vapour-liquid equilibrium partitioning coefficients for VOCs, especially in contaminated soils and groundwater in which they exist, is required. Headspace experiments were performed to quantify the effect of three mixed surfactants, cetyltrimethyl ammonium bromide (CTMAB) with tetrabutylammonium bromide (TBAB), sodium dodecyl sulphate (SDS) with Triton X-405 (TX405), and CTMAB with Triton X-100 (TX100), on the apparent Henry's constants (Hc) of toluene at temperatures ranging from 25 degrees C to 40 degrees C. The Hc values were significantly reduced in the presence of all three mixed surfactants at concentrations above their critical micelle concentrations (CMC). Mixed micellar partitioning, showing effects on the vapour-liquid equilibrium of toluene, was primarily responsible for the significant reduction of Hc in their mixed systems. The mixed surfactants CTMAB-TX100 had the greatest effect on Hc above the CMC, followed by SDS-TX405, then CTMAB-TBAB. Mixed systems of CTMAB-TX100 decreased Hc at concentrations significantly lower than the SDS-TX405 and CTMAB-TBAB concentrations, because of to the lower CMC of CTMAB-TX100. Vapour-liquid equilibrium data were also tested against the model (Hc = H/(1 + K(X - CMC)) that described the partitioning of VOCs in vapour-water-micelle phases. The correlation of Hc with mixed surfactant concentrations (X) and CMC can be utilized as an effective tool to predict the Hc by mixed surfactants. PMID:22988616

Tian, Senlin; Li, Yingjie; Mo, Hong; Ning, Ping

2012-01-01

425

Biotransformation of nitrobenzene by bacteria containing toluene degradative pathways.  

PubMed

Nonpolar nitroaromatic compounds have been considered resistant to attack by oxygenases because of the electron withdrawing properties of the nitro group. We have investigated the ability of seven bacterial strains containing toluene degradative pathways to oxidize nitrobenzene. Cultures were induced with toluene vapor prior to incubation with nitrobenzene, and products were identified by high-performance liquid chromatography and gas chromatography-mass spectrometry. Pseudomonas cepacia G4 and a strain of Pseudomonas harboring the TOL plasmid (pTN2) did not transform nitrobenzene. Cells of Pseudomonas putida F1 and Pseudomonas sp. strain JS150 converted nitrobenzene to 3-nitrocatechol. Transformation of nitrobenzene in the presence of 18O2 indicated that the reaction in JS150 involved the incorporation of both atoms of oxygen in the 3-nitrocatechol, which suggests a dioxygenase mechanism. P. putida 39/D, a mutant strain of P. putida F1, converted nitrobenzene to a compound tentatively identified as cis-1,2-dihydroxy-3-nitrocyclohexa-3,5-diene. This compound was rapidly converted to 3-nitrocatechol by cells of strain JS150. Cultures of Pseudomonas mendocina KR-1 converted nitrobenzene to a mixture of 3- and 4-nitrophenol (10 and 63%, respectively). Pseudomonas pickettii PKO1 converted nitrobenzene to 3- and 4-nitrocatechol via 3- and 4-nitrophenol. The nitrocatechols were slowly degraded to unidentified metabolites. Nitrobenzene did not serve as an inducer for the enzymes that catalyzed its oxidation. These results indicate that the nitrobenzene ring is subject to initial attack by both mono- and dioxygenase enzymes. PMID:1781679

Haigler, B E; Spain, J C

1991-11-01

426

Sarcosine attenuates toluene-induced motor incoordination, memory impairment, and hypothermia but not brain stimulation reward enhancement in mice  

SciTech Connect

Toluene, a widely used and commonly abused organic solvent, produces various behavioral disturbances, including motor incoordination and cognitive impairment. Toluene alters the function of a large number of receptors and ion channels. Blockade of N-methyl-D-aspartate (NMDA) receptors has been suggested to play a critical role in toluene-induced behavioral manifestations. The present study determined the effects of various toluene doses on motor coordination, recognition memory, body temperature, and intracranial self-stimulation (ICSS) thresholds in mice. Additionally, the effects of sarcosine on the behavioral and physiological effects induced by toluene were evaluated. Sarcosine may reverse toluene-induced behavioral manifestations by acting as an NMDA receptor co-agonist and by inhibiting the effects of the type I glycine transporter (GlyT1). Mice were treated with toluene alone or combined with sarcosine pretreatment and assessed for rotarod performance, object recognition memory, rectal temperature, and ICSS thresholds. Toluene dose-dependently induced motor incoordination, recognition memory impairment, and hypothermia and lowered ICSS thresholds. Sarcosine pretreatment reversed toluene-induced changes in rotarod performance, novel object recognition, and rectal temperature but not ICSS thresholds. These findings suggest that the sarcosine-induced potentiation of NMDA receptors may reverse motor incoordination, memory impairment, and hypothermia but not the enhancement of brain stimulation reward function associated with toluene exposure. Sarcosine may be a promising compound to prevent acute toluene intoxications by occupational or intentional exposure. -- Highlights: ? Toluene induces impairments in Rotarod test and novel object recognition test. ? Toluene lowers rectal temperature and ICSS thresholds in mice. ? Sarcosine reverses toluene-induced changes in motor, memory and body temperature. ? Sarcosine pretreatment does not affect toluene-induced reward enhancement.

Chan, Ming-Huan [Department of Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan (China) [Department of Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan (China); Institute of Neuroscience, National Changchi University, Taipei, Taiwan (China); Chung, Shiang-Sheng [Department of Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan (China) [Department of Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan (China); Department of Pharmacy, Yuli Veterans Hospital, Hualien, Taiwan (China); Stoker, Astrid K.; Markou, Athina [Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, CA (United States)] [Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, CA (United States); Chen, Hwei-Hsien, E-mail: hwei@nhri.org.tw [Department of Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan (China) [Department of Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan (China); Division of Mental Health and Addiction Medicine, Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Miaoli County, Taiwan (China)

2012-12-01

427

Microbial characterization of toluene-degrading denitrifying consortia obtained from terrestrial and marine ecosystems.  

PubMed

The degradation characteristics of toluene coupled to nitrate reduction were investigated in enrichment culture and the microbial communities of toluene-degrading denitrifying consortia were characterized by denaturing gradient gel electrophoresis (DGGE) technique. Anaerobic nitrate-reducing bacteria were enriched from oil-contaminated soil samples collected from terrestrial (rice field) and marine (tidal flat) ecosystems. Enriched consortia degraded toluene in the presence of nitrate as a terminal electron acceptor. The degradation rate of toluene was affected by the initial substrate concentration and co-existence of other hydrocarbons. The types of toluene-degrading denitrifying consortia depended on the type of ecosystem. The clone RS-7 obtained from the enriched consortium of the rice field was most closely related to a toluene-degrading and denitrifying bacterium, Azoarcus denitrificians (A. tolulyticus sp. nov.). The clone TS-11 detected in the tidal flat enriched consortium was affiliated to Thauera sp. strain S2 (T. aminoaromatica sp. nov.) that was able to degrade toluene under denitrifying conditions. This indicates that environmental factors greatly influence microbial communities obtained from terrestrial (rice field) and marine (tidal flat) ecosystems. PMID:15278317

An, Y-J; Joo, Y-H; Hong, I-Y; Ryu, H-W; Cho, K-S

2004-10-01

428

Exposure to toluene and stress during pregnancy impairs pups' growth and dams' lactation.  

PubMed

Inhalant misuse starts at an early age, and a large number of users are women in reproductive age. This study investigates whether exposure to toluene, a commonly misused solvent, alone or combined with restraint stress during pregnancy, produces adverse effects in pregnant mice and their offspring during lactation and adulthood. Pregnant animals were exposed to either 8000ppm toluene (30min/twice daily from gestational days 7-19), restraint stress (three times/day during the same gestation period) or both; control mice were only exposed to air. Our results show that toluene, stress and their combination reduced body weight gain in pregnant females without changing food consumption. In the offspring, all treatments resulted in low body weight at weaning, but with the toluene and stress combination this effect was seen from birth. Weight deficiency could not be attributed to poor maternal behavior during the first 3weeks of age, but to a reduction in pro-TRH mRNA expression in the hypothalamic paraventricular nucleus and serum prolactin levels in dams. After weaning, pups that were subjected to toluene and stress during gestation had lower body weight and ate less than control animals. In conclusion, the combined exposure to toluene and stress during pregnancy lead to more pronounced effects in dams and longer-lasting actions in pups than exposure to either toluene or stress. PMID:23933014

Soberanes-Chávez, Paulina; López-Rubalcava, Carolina; de Gortari, Patricia; Cruz, Silvia L

2013-01-01

429

Complete oxidation of toluene under strictly anoxic conditions by a new sulfate-reducing bacterium.  

PubMed Central

A toluene-degrading sulfate-reducing bacterium, strain Tol2, was isolated from marine sediment under strictly anoxic conditions. Toluene was toxic if applied directly to the medium at concentrations higher than 0.5 mM. To provide toluene continuously at a nontoxic concentration, it was supplied in an inert hydrophobic carrier phase. The isolate had oval, sometimes motile cells (1.2 to 1.4 by 1.2 to 2.0 microns). The doubling time was 27 h. Toluene was completely oxidized to CO2, as demonstrated by measurement of the degradation balance. The presence of carbon monoxide dehydrogenase and formate dehydrogenase indicated a terminal oxidation of acetyl coenzyme A via the CO dehydrogenase pathway. The use of hypothetical intermediates of toluene degradation was tested in growth experiments and adaptation studies with dense cell suspensions. Results do not support a degradation of toluene via one of the cresols or methylbenzoates, benzyl alcohol, or phenylacetate as free intermediate. Benzyl alcohol did not serve as growth substrate; moreover, it was a strong, specific inhibitor of toluene degradation, whereas benzoate utilization was not affected by benzyl alcohol. Sequencing of 16S rRNA revealed a relationship to the metabolically dissimilar genus Desulfobacter and on a deeper level to the genus Desulfobacterium. The new genus and species Desulfobacula toluolica is proposed. Images

Rabus, R; Nordhaus, R; Ludwig, W; Widdel, F

1993-01-01

430

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

2013-01-01

431

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. Although the microflora changed during the initial period (before day 40), transformation of the bacterial component was hardly observed after day 51. Statistical analyses of the DGGE profiles indicated that the bacterial community was almost unaffected by the environmental factors, such as adding ozone, high-level nitrogen supply, increase of loading toluene, and the shutdown of the RSB. The DGGE profile using tmoA-like genes, which encode proteins belonging to the hydroxylase component mono-oxygenases involved in the initial attack of aerobic benzene, toluene, ethylbenzene, and xylene degradation, confirmed the existence of toluene-degrading bacteria. There were at least four kinds of toluene-degradable bacteria having tmoA-like genes up to day 36, which decreased to two species after day 40. Sequence analysis after DGGE profiling revealed that Burkholderia cepacia, Sphingobacterium multivorum, and Pseudomonas putida were present in the biofilter. Only Alicycliphilus denitrificans was present throughout the whole operation period. In the initial stage of operating the RSB, many types of bacteria may have tried to adapt to the conditions, and subsequently, only selected bacteria were able to grow and to degrade toluene. PMID:22866576

Okunishi, Suguru; Morita, Yasutaka; Higuchi, Takashi; Maeda, Hiroto; Nishi, Katsuji

2012-07-01

432

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

433

Gene expression profiling in the fetal cardiac tissue after folate and low dose trichloroethylene exposure  

PubMed Central

Background Previous studies show gene expression alterations in rat embryo hearts and cell lines that correspond to the cardio-teratogenic effects of trichloroethylene (TCE) in animal models. One potential mechanism of TCE teratogenicity may be through altered regulation of calcium homeostatic genes with a corresponding inhibition of cardiac function. It has been suggested that TCE may interfere with the folic acid/methylation pathway in liver and kidney and alter gene regulation by epigenetic mechanisms. According to this hypothesis, folate supplementation in the maternal diet should counteract TCE effects on gene expression in the embryonic heart. Approach To identify transcriptional targets altered in the embryonic heart after exposure to TCE, and possible protective effects of folate, we used DNA microarray technology to profile gene expression in embryonic mouse hearts with maternal TCE exposure and dietary changes in maternal folate. Results Exposure to low doses of TCE (10ppb) caused extensive alterations in transcripts encoding proteins involved in transport, ion channel, transcription, differentiation, cytoskeleton, cell cycle and apoptosis. Exogenous folate did not offset the effects of TCE exposure on normal gene expression and both high and low levels of folate produced additional significant changes in gene expression. Conclusions A mechanism where TCE induces a folate deficiency does not explain altered gene expression patterns in the embryonic mouse heart. The data further suggest that use of folate supplementation, in the presence of this toxin, may be detrimental and non-protective of the developing embryo.

Caldwell, Patricia T.; Manziello, Ann; Howard, Jamie; Palbykin, Brittany; Runyan, Raymond B.; Selmin, Ornella

2014-01-01

434

Low dose trichloroethylene alters cytochrome P450 - 2C subfamily expression in the developing chick heart  

PubMed Central

Trichloroethylene (TCE) is an organic solvent and common environmental contaminant. TCE exposure is associated with heart defects in humans and animal models. Primary metabolism of TCE in adult rodent models is by specific hepatic cytochrome P450 enzymes (Lash et al., 2000). As association of TCE exposure with cardiac defects is in exposed embryos prior to normal liver development, we investigated metabolism of TCE in the early embryo. Developing chick embryos were dosed in ovo with environmentally relevant doses of TCE (8 ppb and 800 ppb) and RNA was extracted from cardiac and extra-cardiac tissue (whole embryo without heart). Real time PCR showed upregulation of CYP2H1 transcripts in response to TCE exposure in the heart. No detectable cytochrome expression was found in extra-cardiac tissue. As seen previously, the dose response was non-monotonic and 8ppb elicited stronger upregulation than 800 ppb. Immunostaining for CYP2C subfamily expression confirmed protein expression and showed localization in both myocardium and endothelium. TCE exposure increased protein expression in both tissues. These data demonstrate that the earliest embryonic expression of phase I detoxification enzymes is in the developing heart. Expression of these CYPs is likely to be relevant to the susceptibility of the developing heart to environmental teratogens.

Makwana, Om; Ahles, Lauren; Lencinas, Alejandro; Selmin, Ornella I.; Runyan, Raymond B.

2013-01-01

435

[Characteristics and influencing factors of trichloroethylene adsorption in different soil types].  

PubMed

Adsorption plays an important role in the transport and the fate of trichloroethylene (TCE) in soil. Six types of soil, including two types of natural soil with different organic carbon content and four types of soil with the low aggregation of "soft carbon" pre-treated by hydrogen peroxide or with all organic carbon removed by high temperature ignition from the original soil, were adopted as adsorbents. The effects of parameters (organic carbon content and composition, minerals, the initial TCE concentration, solution pH, moisture content and ionic strength) on TCE adsorption capacity were examined. The results showed that the soil adsorption isotherm was non-linear within the experimental range. The TCE adsorption capacity was increased and the contribution rate of the minerals to the sorption was reduced with the increase of the organic carbon content. The adsorption of TCE in the soil was the result of the combined action of both organic carbon and minerals, in which organic carbon played a major part, whereas the role of minerals could not be neglected. As the initial TCE concentration increased, the contribution rate of the minerals to the sorption went down. The adsorption isotherm of "soft carbon" was linear, while the "hard carbon" was non-linear. Moreover, the adsorption capacity was increased by increasing the ionic strength. In contrast, neither pH nor moisture content had any influence on TCE adsorption. PMID:23323434

He, Long; Qiu, Zhao-Fu; Lü, Shu-Guang; Lu, Zhi-Chang; Wang, Zhi-Li; Sui, Qian; Lin, Kuang-Fei; Liu, Yong-Di

2012-11-01

436

Pulmonary toxicity of trichloroethylene in mice. Covalent binding and morphological manifestations  

SciTech Connect

We examined the time course of trichloroethylene (TCE)-induced pulmonary injury and focused on morphological changes and covalent binding of (/sup 14/C)TCE soon after administration of a single dose of TCE (2000 mg/kg) to CD-1 male mice. At 1 hr after chemical treatment, Clara cells of the bronchiolar epithelium exhibited necrotic changes involving the mitochondria and endoplasmic reticulum. Dilatation of the endoplasmic reticulum became more severe at 2 hr after TCE administration and, by 4 hr, distended cisternae coalesced to form small vacuoles within the cytoplasmic matrix of the Clara cell. The severity of cellular damage increased progressively between 8 and 12 hr and, by 24 hr, the majority of Clara cells within an airway were severely vacuolated. Covalent binding of (/sup 14/C)TCE to lung macromolecules was evident at 1 hr, peaked at 4 hr, declined thereafter, and reached a plateau between 12 and 24 hr. Peak binding (142.6 +/- 31.8 nmol/g of wet weight) represented approximately 20% of (/sup 14/C)TCE distributed to the lung. Although the levels of binding in the liver were at all times greater than those in the lung, liver injury was relatively insignificant. The results demonstrate a positive correlation between the onset of Clara cell injury and the formation of reactive metabolites, as assessed by covalent binding of (/sup 14/C)TCE.

Forkert, P.G.; Birch, D.W.

1989-01-01

437

Phenol and trichloroethylene degradation by Pseudomonas cepacia G4: kinetics and interactions between substrates.  

PubMed Central

Intact cells of Pseudomonas cepacia G4 completely degraded trichloroethylene (TCE) following growth with phenol. Degradation kinetics were determined for both phenol, used to induce requisite enzymes, and TCE, the target substrate. Apparent Ks and Vmax values for degradation of phenol by cells were 8.5 microM and 466 nmol/min per mg of protein, respectively. At phenol concentrations greater than 50 microM, phenol degradation was inhibited, yielding an apparent second-order inhibitory value, KSI, of 0.45 mM as modeled by the Haldane expression. A partition coefficient for TCE was determined to be 0.40 +/- 0.02, [TCEair]/[TCEwater], consistent with Henry's law. To eliminate experimental problems associated with TCE volatility and partitioning, a no-headspace bottle assay was developed, allowing for direct and accurate determinations of aqueous TCE concentration. By this assay procedure, apparent Ks and Vmax values determined for TCE degradation by intact cells were 3 microM and 8 nmol/min per mg of protein, respectively. Following a transient lag period, P. cepacia G4 degraded TCE at concentrations of at least 300 microM with no apparent retardation in rate. Consistent with Ks values determined for degradation, TCE significantly inhibited phenol degradation.

Folsom, B R; Chapman, P J; Pritchard, P H

1990-01-01

438

Identification of serum biomarkers for occupational medicamentosa-like dermatitis induced by trichloroethylene using mass spectrometry.  

PubMed

Occupational medicamentosa-like dermatitis induced by trichloroethylene (OMLDT) is an autoimmune disease and it has become a serious occupational health hazard. In the present study, we collected fasting blood samples from patients with OMLDT (n=18) and healthy volunteers (n=33) to explore serum peptidome patterns. Peptides in sera were purified using weak cation exchange magnetic beads (MB-WCX), and analyzed by matrix-assisted laser desorption ionization time-of-flight-mass spectrometry (MALDI-TOF-MS) and ClinProTools bioinformatics software. The intensities of thirty protein/peptide peaks were significantly different between the healthy control and OMLDT patients. A pattern of three peaks (m/z 2106.3, 2134.5, and 3263.67) was selected for supervised neural network (SNN) model building to separate the OMLDT patients from the healthy controls with a sensitivity of 95.5% and a specificity of 73.8%. Furthermore, two peptide peaks of m/z 4091.61 and 4281.69 were identified as fragments of ATP-binding cassette transporter family A member 12 (ABCA12), and cationic trypsinogen (PRRS1), respectively. Our findings not only show that specific proteomic fingerprints in the sera of OMLDT patients can be served as a differentiated tool of OMLDT patients with high sensitivity and high specificity, but also reveal the novel correlation between OMLDT with ABC transports and PRRS1, which will be of potential value for clinical and mechanistic studies of OMLDT. PMID:23994554

Hong, Wen-Xu; Liu, Wei; Zhang, Yanfang; Huang, Peiwu; Yang, Xifei; Ren, Xiaohu; Ye, Jinbo; Huang, Haiyan; Tang, Haiyan; Zhou, Guifeng; Huang, Xinfeng; Zhuang, Zhixiong; Liu, Jianjun

2013-11-15

439

Physiologically-based pharmacokinetic model for trichloroethylene considering enterohepatic recirculation of major metabolites  

SciTech Connect

Trichloroacetic acid (TCA) is a major metabolite of trichloroethylene (TRI) thought to contribute to its hepatocarcinogenic effects in mice. Recent studies have shown that peak blood concentrations of TCA in rats do not occur until approximately 12 hours following an oral dose of TRI. However, blood concentrations of TRI reach a maximum within an hour and are nondetectable after 2 hours. The results of a study which examined the enterohepatic recirculation (EHC) of the principle TRI metabolites was used to develop a physiologically-based pharmacokinetic model for TRI, which includes enterohepatic recirculation of its metabolites. The model quantitatively predicts the uptake, distribution and elimination of TRI, trichloroethanol, trichloroethanol-glucuronide, and TCA and includes production of metabolites through the enterohepatic recirculation pathway. Physiologic parameters used in the model were obtained from the literature. Parameters for TRI metabolism were taken from Fisher et al. Other kinetic parameters were found in the literature or estimated from experimental data. The model was calibrated to data from experiments of an earlier study where TRI was orally administered. Verification of the model was conducted using data on the enterohepatic recirculation of TCEOH and TCA, choral hydrate data (infusion doses) from Merdink, and TRI data from Templin and Larson and Bull.

Stenner, R.D.; Bull, R.J. [Pacific Northwest National Lab., Richland, WA (United States)

1998-06-01

440

Removal of trichloroethylene from soil using the hydration of calcium oxide.  

PubMed

Quicklime addition to soil at a remediation site was observed to sufficiently reduce TCE levels, but the cause of the removal could not be confirmed with the field data collected. Potential mechanisms for CaO treatment of trichloroethylene (TCE) in soil include degradation and volatilization. Since earlier studies found TCE degradation to occur during the hydration of CaO under conditions where volatilization was limited, research was conducted on mechanisms of TCE removal from soil by CaO application under conditions where volatilization was allowed to occur. TCE volatilization in soil treated with 0%, 5%, 10%, and 20% CaO doses was measured in experiments where the degree of volatilization could be tracked. The total TCE removal from soil spiked with TCE at CaO doses from 5% to 20% ranged from 97% to 99% of the initial TCE mass. Volatilization accounted for 64.4-92.5% of the TCE removal, with unrecovered TCE and TCE degradation accounting for the remaining fraction. The greater heat encountered with higher CaO doses helped minimize obstacles to TCE volatilization, such as high soil organic and clay content. Treatment with a 20% CaO dose, however, led to the formation of byproducts such as dichloroacetylene. TCE degradation to dichloroacetylene at the 20% CaO dose ranged from 2.7% to 6.4% of the initial TCE. Volatilization was concluded to be the dominant process for TCE removal from soil during CaO treatment. PMID:21414713

Ko, Jae Hac; Musson, Steve; Townsend, Timothy

2011-07-01

441

Kinetics of chlorinated hydrocarbon degradation by Methylosinus trichosporium OB3b and toxicity of trichloroethylene.  

PubMed Central

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. 1,1-Dichloroethylene was a very poor substrate. TCE was found to be toxic for the cells, and this phenomenon was studied in detail. Addition of activated carbon decreased the acute toxicity of high levels of TCE by adsorption, and slow desorption enabled the cells to partially degrade TCE. TCE was also toxic by inactivating the cells during its conversion. The degree of inactivation was proportional to the amount of TCE degraded; maximum degradation occurred at a concentration of 2 mumol of TCE mg of cells-1. During conversion of [14C]TCE, various proteins became radiolabeled, including the alpha-subunit of the hydroxylase component of soluble methane monooxygenase. This indicated that TCE-mediated inactivation of cells was caused by nonspecific covalent binding of degradation products to cellular proteins. Images

Oldenhuis, R; Oedzes, J Y; van der Waarde, J J; Janssen, D B

1991-01-01

442

Concentration of Trichloroethylene in Breast Milk and Household Water from Nogales, Arizona  

PubMed Central

The United States Environmental Protection Agency has identified quantification of trichloroethylene (TCE), an industrial solvent, in breast milk as a high priority need for risk assessment. Water and milk samples were collected from 20 households by a lactation consultant in Nogales, Arizona. Separate water samples (including tap, bottled and vending machine) were collected for all household uses: drinking, bathing, cooking, and laundry. A risk factor questionnaire was administered. Liquid-liquid extraction with diethyl ether was followed by GC-MS for TCE quantification in water. Breast milk underwent homogenization, lipid hydrolysis and centrifugation prior to extraction. The limit of detection was 1.5 ng/mL. TCE was detected in 7 of 20 mothers’ breast milk samples. The maximum concentration was 6 ng/mL. TCE concentration in breast milk was significantly correlated with the concentration in water used for bathing (?=0.59, p=0.008). Detection of TCE in breast milk was more likely if the infant had a body mass index <14 (RR=5.2, p=0.02). Based on average breast milk consumption, TCE intake for 5% of the infants may exceed the proposed US EPA Reference Dose. Results of this exploratory study warrant more in depth studies to understand risk of TCE exposures from breast milk intake.

Beamer, Paloma I.; Luik, Catherine E.; Abrell, Leif; Campos, Swilma; Martinez, Maria Elena; Saez, A. Eduardo

2013-01-01

443

Demonstration of efficient trichloroethylene biodegradation in a hollow-fiber membrane bioreactor  

SciTech Connect

Rapid cometabolism of trichloroethylene (TCE) by pure cultures of Methylosinus trichosporium OB3b PP358 was demonstrated in a two-stage hollow-fiber membrane bioreactor over the course of 3 weeks. PP358 was grown in a continuous-flow chemostat and circulated through the shell of a hollow-fiber membrane module (HFMM), while TCE contaminated water was pumped through the fiber lumen. In parallel-flow HFMM biological experiments, 82% to 89% of the influent TCE was removed from the lumen with 99% of the transferred TCE undergoing biodegradation. Biological experiments in a larger capacity baffled radial-flow HFMM resulted in 66% to 99% TCE transferred and 93% to 96% TCE biodegradation at lumen residence times of between 1.5 and 3.7 min. Biodegradation was maintained throughout the experiments at pseudo-first-order biodegradation rate constants of 0.41 to 2.8 L/mg TSS/day. Best-fit computer modeling of the baffled radial-flow biological process estimated mass transfer coefficients as large as 2.7 {times} 10{sup {minus}2} cm/min. The computer model was also shown to simulate the experimental results quite well.

Pressman, J.G.; Georgiou, G.; Speitel, G.E. Jr. [Univ. of Texas, Austin, TX (United States)] [Univ. of Texas, Austin, TX (United States)

1999-03-20

444

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

445

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

2011-08-01

446

Redox control for electrochemical dechlorination of trichloroethylene in bicarbonate aqueous media  

PubMed Central

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 pseudo-first order model is used to describe the degradation of TCE, the first order rate constant (k) increased 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.

Mao, Xuhui; Ciblak, Ali; Amiri, Mohammad; Alshawabkeh, Akram N.

2011-01-01

447

A Study of Groundwater Matrix Effects for the Destruction of Trichloroethylene Using Fe/Pd Nanoaggregates  

PubMed Central

Iron nanoaggregates have been prepared using the sodium borohydride reduction method and post-coated with Pd using aqueous phase electro-deposition. The Fe/Pd nanoaggregates were used to examine dechlorination of trichloroethylene (TCE) with regard to matrix effects using materials representative of a potential zero-valent metal remediation site surrounding the Paducah gaseous diffusion plant in Paducah, KY. A surface-area-normalized first-order rate constant of 1.4 × 10–1 L m–2 h–1 was obtained for the case of ideal dechlorination of 19.6 mg L–1 TCE at room temperature and pH 6.2 using 0.5 g L–1 Fe/Pd (0.42 wt % Pd) loading. This value decreases by an order of magnitude to 1.9 × 10–2 L m–2 h–1 when the reaction is carried out in a realistic background matrix when the pH is high (8.8). For all variables tested, Pd content has the most impact on reaction rates. Circulating batch-column experiments are used to study dechlorination under flow conditions and demonstrate the ability of nonstabilized Fe/Pd nanoaggregates to remove significant amounts of TCE (80–90%) over a broad range of groundwater velocities (12.9–83 ft per day) using moderate metal loadings (0.23–0.5 g L–1).

Meyer, D.E.; Hampson, S.; Ormsbee, L.; Bhattacharyya, D.

2010-01-01

448

Health-hazard evaluation report HETA 86-206-1744, Rotorex, Walkersville, Maryland. [Trichloroethylene  

SciTech Connect

In response to a labor/management request, an evaluation was made of sudden illness in workers at the Rotorex facility in Walkersville, Maryland, employing about 350 workers. The facility had been closed after an explosion on January 29, 1986, due to a malfunctioning boiler-regulator valve. After reopening on February 3, ten employees became ill with headaches, nausea, dizziness, and chest pain. Eight were tested for carbon-monoxide (CO) blood levels; five had elevated carboxyhemoglobin (COHb) levels. Another outbreak occurred on February 19, with 18 employees removed by stretcher. Tests for CO, trichloroethylene (TCE), fluorocarbons, and methylene chloride exposure were negative. The authors conclude that illness on February 3 was due to combined CO and TCE exposures; illness on February 19 was an anxiety reaction. It is recommended that a joint management/union health and safety committee be formed that meets regularly, with easy employee access. Development of evacuation procedures, evaluation of ventilation systems, study of welding and brazing operations for hazardous substances, determination of oil mist levels, weekly bacterial check of central coolant, evaluation of Freon-11 use in open cans, study of noise exposure, and replacement of a welding curtain are additional recommendations.

Kerndt, P.R.; Sinks, T.H.; Wallingford, K.M.

1986-10-01

449

Composite electrodes consisting of metal and oxidized carbon particles for complete degradation of trichloroethylene in acetonitrile  

SciTech Connect

Electrochemical degradation of trichloroethylene (TCE) was studied by flow-through electrolysis in acetonitrile (AN). TCE was electrolyzed to acetylene in a quantitative yield at a composite electrode consisting of stainless steel (SS) and oxidatively pretreated glassy carbon (GCO) particles. On the GCO particle TCE was reduced to intermediate C[sub 2]HCl, which was further reduced to C[sub 2]H[sub 2] on the SS particle. Although SS was not active for TCE reduction, SS displayed higher activity for the reduction of C[sub 2]HCl than GCO. The activity of SS was attributed mainly to Ni and CR atoms at the SS surface, but SS demonstrated higher activity than Ni and Cr in H[sub 2]O-AN media. At potentials below [minus]2.1 V vs. Ag[vert bar]10 mM Ag[sup +] (AN), TCE in 1% H[sub 2]O + AN was converted to C[sub 2]H[sub 2] in a 100% yield.

Nagaoka, Tsutomu; Yamashita, Junji; Takase, Mika; Ogura, Kotaro (Yamaguchi Univ., Tokiwadai (Japan). Dept. of Applied Chemistry)

1994-06-01

450

Degradation of Trichloroethylene and Dichlorobiphenyls by Iron-Based Bimetallic Nanoparticles  

PubMed Central

Bimetallic nanoparticles of Ni/Fe and Pd/Fe were used to study the degradation of trichloroethylene (TCE) at room temperature. The activity for different iron-based nanoparticles with nickel as the catalytic dopant was analyzed using iron mass-normalized hydrogen generation rate. Degradation kinetics in terms of surface area-normalized rate constant was observed to have a strong correlation with the hydrogen generated by iron oxidation. A sorption study was conducted, and a mathematical model was derived that incorporates the reaction and Langmuirian-type sorption terms to estimate the intrinsic rate constant and rate-limiting step in the degradation process, assuming negligible mass transfer resistance of TCE to the solid particles phase. A longevity study through repeated cycle experiments was conducted to analyze the effect of activity loss on the reaction mechanistic pathway, and the results showed that the attenuation in the nanoparticles activity did not adversely affect the reaction mechanisms in generating gaseous products such as ethylene and ethane.

Tee, Yit-Hong; Bachas, Leonidas; Bhattacharyya, Dibakar

2009-01-01

451

Microcosm and in situ field studies of enhanced biotransformation of trichloroethylene by phenol-utilizing microorganisms.  

PubMed

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. PMID:8357259

Hopkins, G D; Semprini, L; McCarty, P L

1993-07-01

452

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

453

Continuous degradation of trichloroethylene by Xanthobacter sp. strain Py2 during growth on propene.  

PubMed Central

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 microns 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 0.34g of TCE per g of biomass. The biomass yield on propene was not affected by the cometabolic degradation of TCE.

Reij, M W; Kieboom, J; de Bont, J A; Hartmans, S

1995-01-01

454

Performance characterization of a model bioreactor for the biodegradation of trichloroethylene by Pseudomonas cepacia G4.  

PubMed

Pseudomonas cepacia G4 grown in chemostats with phenol demonstrated constant specific degradation rates for both phenol and trichloroethylene (TCE) over a range of dilution rates. Washout of cells from chemostats was evident at a dilution rate of 0.2 h-1 at 28 degrees C. Increased phenol concentrations in the nutrient feed led to increased biomass production with constant specific degradation rates for both phenol and TCE. The addition of lactate to the phenol feed led to increased biomass production but lowered specific phenol and TCE degradation rates. The maximum potential for TCE degradation was about 1.1 g per day per g of cell protein. Cell growth and degradation kinetic parameters were used in the design of a recirculating bioreactor for TCE degradation. In this reactor, the total amount of TCE degraded increased as either reaction time or biomass was increased. TCE degradation was observed up to 300 microM TCE with no significant decreases in rates. On the average, this reactor was able to degrade 0.7 g of TCE per day per g of cell protein. These results demonstrate the feasibility of TCE bioremediation through the use of bioreactors. PMID:1872599

Folsom, B R; Chapman, P J

1991-06-01

455

The Relationship between the Occupational Exposure of Trichloroethylene and Kidney Cancer  

PubMed Central

Trichloroethylene (TCE) has been widely used as a degreasing agent in many manufacturing industries. Recently, the International Agency for Research on Cancer presented “sufficient evidence” for the causal relationship between TCE and kidney cancer. The aim of this study was to review the epidemiologic evidences regarding the relationship between TCE exposure and kidney cancer in Korean work environments. The results from the cohort studies were inconsistent, but according to the meta-analysis and case–control studies, an increased risk for kidney cancer was present in the exposure group and the dose–response relationship could be identified using various measures of exposure. In Korea, TCE is a commonly used chemical for cleaning or degreasing processes by various manufacturers; average exposure levels of TCE vary widely. When occupational physicians evaluate work-relatedness kidney cancers, they must consider past exposure levels, which could be very high (>100 ppm in some cases) and associated with jobs, such as plating, cleaning, or degreasing. The exposure levels at a manual job could be higher than an automated job. The peak level of TCE could also be considered an important exposure-related variable due to the possibility of carcinogenesis associated with high TCE doses. This review could be a comprehensive reference for assessing work-related TCE exposure and kidney cancer in Korea.

2014-01-01

456

Characterization of gamma-alumina-supported manganese oxide as an incineration catalyst for trichloroethylene.  

PubMed

Trichloroethylene (TCE) decomposition over a MnOx/ gamma-Al2O3 catalyst in a fixed-bed reactor was conducted in this study. The MnOx/gamma-Al2O3 powders were prepared by the incipient wetness impregnation method with aqueous solution of manganese nitrate. The catalysts were characterized by DTA-TGA, XRD, porosity analysis, SEM, EDX, and XPS. The results show that the main distinct weight loss is found at the temperature around 373 and 873 K,the MnO peaks (2theta = 34.9 degrees and 40.5 degrees) are only observed crystal phase on the fresh catalyst, the SEM image of the MnOx-impregnated gamma-Al2O3 support is much different from the calcined catalyst, and the Mn element quantity on the catalyst surface is higher than that of the impregnated support. The products and reactants distributions from the oxidation of TCE over MnOx/gamma-Al2O3 were analyzed by GC. The results show that the TCE conversion starts from 5% at 443 K and rises to very high values in the 673-873 K ranges and that the CO2 yield also pushes to 99% at the same temperature ranges. HCl and Cl2 are the other main products with little halogenated VOC intermediates. PMID:12542307

Tseng, Ting-Ke; Chu, Hsin; Hsu, Han-Hsuan

2003-01-01

457

Synthesis and characterization of supported polysugar-stabilized palladium nanoparticle catalysts for enhanced hydrodechlorination of trichloroethylene.  

PubMed

Palladium (Pd) nanoparticle catalysts were successfully synthesized within an aqueous phase using sodium carboxymethyl cellulose (CMC) as a capping ligand which offers a green alternative to conventional nanoparticle synthesis techniques. The CMC-stabilized Pd nanoparticles were subsequently dispersed within support materials using the incipient wetness impregnation technique for utilization in heterogeneous catalyst systems. The unsupported and supported (both calcined and uncalcined) Pd nanoparticle catalysts were characterized using transmission electron microscopy, energy dispersive x-ray spectrometry, x-ray diffraction, and Brunauer-Emmett-Teller surface area measurement and their catalytic activity toward the hydrodechlorination of trichloroethylene (TCE) in aqueous media was examined using homogeneous and heterogeneous catalyst systems, respectively. The unsupported Pd nanoparticles showed considerable activity toward the degradation of TCE, as demonstrated by the reaction kinetics. Although the supported Pd nanoparticle catalysts had a lower catalytic activity than the unsupported particles that were homogeneously dispersed in the aqueous solutions, the supported catalysts retained sufficient activity toward the degradation of TCE. In addition, the use of the hydrophilic Al(2)O(3) support material induced a mass transfer resistance to TCE that affected the initial hydrodechlorination rate. This paper demonstrates that supported Pd catalysts can be applied to the heterogeneous catalytic hydrodechlorination of TCE. PMID:22743584

Bacik, Deborah B; Zhang, Man; Zhao, Dongye; Roberts, Christopher B; Seehra, Mohinar S; Singh, Vivek; Shah, Naresh

2012-07-27

458

A cometabolic kinetics model incorporating enzyme inhibition, inactivation, and recovery. 2: Trichloroethylene degradation experiments  

SciTech Connect

A cometabolism enzyme kinetics model has been presented which takes into account changes in bacterial activity associated with enzyme inhibition, inactivation of enzyme resulting from product toxicity, and respondent synthesis of new enzyme. Although this process is inherently unsteady-state, the model assumes that cometabolic degradation of a compound exhibiting product toxicity can be modeled as pseudo-steady-state under certain conditions. In its simplified form, the model also assumes that enzyme inactivation is directly proportional to nongrowth substrate oxidation, and that recovery is directly proportional to growth substrate oxidation. In part 1, model derivation, simplification, and analyses were described. In this article, model assumptions are tested by analyzing data from experiments examining trichloroethylene (TCE) degradation by the ammonia-oxidizing bacterium Nitrosomonas europaea in a quasi-stead-state bioreactor. Model solution results showed TCE to be a competitive inhibitor of ammonia oxidation, with TCE affinity for ammonia monooxygenase (AMO) being about four times greater than that of ammonia for the enzyme. Inhibition was independent of TCE oxidation and occurred essentially instantly upon exposure to TCE. In contrast, inactivation of AMO occurred more gradually and was proportional to the rate and amount of TCE oxidized. Evaluation of other O{sub 2}-dependent enzymes and electron transport proteins suggested that TCE-related damage was predominantly confined to AMO. In response to inhibition and/or inactivation, bacterial recovery was initiated, even in the presence of TCE, implying that membranes and protein synthesis systems were functioning.

Ely, R.L.; Hyman, M.R.; Arp, D.J.; Guenther, R.B.; Williamson, K.J. [Oregon State Univ., Corvallis, OR (United States)

1995-05-05

459

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)] [Univ. of Delaware, Newark, DE (United States); Brendley, W.H. Jr. [Philadelphia Coll. of Textiles, Philadelphia, PA (United States). Dept. of Chemistry] [Philadelphia Coll. of Textiles, Philadelphia, PA (United States). Dept. of Chemistry

1998-06-01

460

Differential Immunotoxicity Induced by Two Different Windows of Developmental Trichloroethylene Exposure  

PubMed Central

Developmental exposure to environmental toxicants may induce immune system alterations that contribute to adult stage autoimmune disease. We have shown that continuous exposure of MRL+/+ mice to trichloroethylene (TCE) from gestational day (GD) 0 to postnatal day (PND) 49 alters several aspects of CD4+ T cell function. This window of exposure corresponds to conception-adolescence/young adulthood in humans. More narrowly defining the window of TCE developmental exposure causes immunotoxicity that would establish the stage at which avoidance and/or intervention would be most effective. The current study divided continuous TCE exposure into two separate windows, namely, gestation only (GD0 to birth (PND0)) and early-life only (PND0-PND49). The mice were examined for specific alterations in CD4+ T cell function at PND49. One potentially long-lasting effect of developmental exposure, alterations in retrotransposon expression indicative of epigenetic alterations, was found in peripheral CD4+ T cells from both sets of developmentally exposed mice. Interestingly, certain other effects, such as alterations in thymus cellularity, were only found in mice exposed to TCE during gestation. In contrast, expansion of memory/activation cell subset of peripheral CD4+ T cells were only found in mice exposed to TCE during early life. Different windows of developmental TCE exposure can have different functional consequences.

Gilbert, Kathleen M.; Woodruff, William; Blossom, Sarah J.

2014-01-01

461

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

2013-11-15