Trichloroethylene In Air Research Articles

Development of a priority list of chemical mixtures occurring at 1188 hazardous waste sites, using the hazdat database

Under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA or Superfund) section 104 mandate, as amended by the Superfund Amendments and Reauthorization Act (SARA) of 1986 USC 9604 (i)(2), the Agency for Toxic Substances and Disease Registry (ATSDR) is to identify individual substances and combinations of substances that pose the greatest public health hazard at hazardous waste sites. This has led to certain mandated activities of the Agency, including development of toxicological profiles, identification of data gaps, and, ultimately, establishment of a research agenda. The Agency has also developed HazDat, a database that captures pertinent information from public health assessments conducted at hazardous waste sites. As a preliminary step, data from sites have been analysed to identify the combinations of chemicals found in various environmental media. The most frequently found combinations were perchloroethylene (PERC) and trichloroethylene (TCE) in water (23.5% of sites); chromium (Cr) and lead (Ph) in soil (20.5%); benzene and toluene in air (3.5%); PERC, 1,1,1-trichloroethane (1,1,1-TCA) and TCE in water (11.6%); Cr, cadmium (Cd) and Pb in soil (12.0%); and benzene, PERC and TCE in air (2.2%). The findings of this analysis can be enhanced by factoring into the algorithm paramenters such as toxicity, source contribution, and likelihood of human exposure similar to that used for the Agency's priority list of 275 single substances. Assessment of the impact of chemical mixtures on human health is a formidable task, and estimating the toxicity of such mixtures, including the role of chemical interactions, is an equally demanding challenge. Because limited experimental data exist for chemical interactions, alternative methods such as predictive approaches and in vitro techniques are needed to address the many substances and their potential combinations.

ChemInform Abstract: Kinetics of the Oxidation of Trichloroethylene in Air via Heterogeneous Photocatalysis

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Kinetics of the Oxidation of Trichloroethylene in Air via Heterogeneous Photocatalysis

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 used to make kinetic measurements. Observations of the reaction rate of trichloroethylene were made while varying parameters such as catalyst loading, feed flow rate, feed composition, and ultraviolet light energy. The observed reaction rates are higher by several orders of magnitude than those previously reported in the literature, and an expression for the prediction of rate as a function of reactant partial pressure is provided. The rate of reaction of the DCAC intermediate is also discussed. Air is shown to be an optimum oxidant, and an optimum humidity is established. The reaction is shown to proceed indefinitely under dry conditions, supporting the existence of a chlorine radical propagated surface reaction.

Products, Intermediates, Mass Balances, and Reaction Pathways for the Oxidation of Trichloroethylene in Air via Heterogeneous Photocatalysis

Studies of the photocatalytic reaction of a solution of trichloroethylene in the air and in contact with UV-irradiated titanium dioxide have produced conflicting reports in regard to the composition of the product mixture. This paper resolves these discrepancies by reporting the results of experiments designed to identify and quantify intermediates, products, and reaction pathways. Mass balances are closed in differential and integral modes to ascertain the effects of factors such as the extent of conversion, feed composition, and photon energy on the composition of the product stream

A Gas Lift Bioreactor for Removal of Contaminants from the Vapor Phase

The cometabolic degradation of trichloroethylene (TCE) as a vapor by two aromatic-metabolizing pseudomonads was evaluated in an airlift reactor. These microorganisms were able to degrade 90 to 95% of TCE in air at concentrations at the reactor inlet of 300 to 4,000 mug/liter. Although exposure of the cells to high inlet concentrations of TCE (4 mg/liter) caused a decline in enzyme-specific activity and TCE removal efficiency, this loss in activity could be prevented or delayed by increasing the rate of cosubstrate addition. Under the appropriate operating conditions, the microorganisms were able to degrade even high concentrations of TCE and activity of the cells in the reactor could be maintained for periods of at least 2 weeks.

Fiber-optic spectrochemical emissions sensor: a detector for volatile chlorinated compounds

We present a fiber-optic sensor developed to measure volatile chlorine-containing compounds in the gas phase. This unique sensor, called the HaloSnif TM, is based on the atomic emission of chlorine. The HaloSnif sensor uses a critical orifice air inlet (a 50 μm capillary tube) and a radio frequency (r.f.) excited helium plasma to excite the ambient air sample. A fiber-optic cable transmits the chlorine emission intensity to a signal-processing module, where it is optically filtered and amplified. The HaloSnif system consists of a miniaturized probe (∼ 10 cm × 4 cm), fiber-optic cable, r.f. power supply, and a flow-control and signal-processig module. The compact robust system has been successfully field-tested at several waste-remediation sites. The detection limit for trichloroethylene in air is 1 ppm, with over four orders of linear response. Furthermore, HaloSnif is capable of measuring concentrations of any gas-phase chlorine-containing compound.

Subclinical and reversible hepatic effects of occupational exposure to trichloroethylene.

To detect early hepatic effects of chronic exposure to low-level trichloroethylene (TCE), serum total cholesterol (T-C), high-density-lipoprotein cholesterol (HDL-C) and activities of three serum enzymes [aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl transpeptidase (GGT)] were determined in 148 workers (a cross-sectional study) and in 13 workers (a 2-year follow-up study) occupationally exposed to TCE in air. In the cross-sectional study, three exposure groups were defined by urinary total trichloro-compounds (U-TTC) levels of the workers [low-exposure group (n = 49): U-TTC < 10 mg/g creatinine; moderate-exposure group (n = 56): U-TTC 10- < 100; high-exposure group (n = 43): U-TTC > or = 100]. With increasing exposure levels, T-C (P = 0.143 by ANOVA) and HDL-C (P = 0.080 by ANOVA) slightly increased. The exposure, however, had no effect on the activities of the three serum enzymes. In the follow-up study, the fluctuations in U-TTC were well reflected in subclinical changes in HDL-C, AST, and GGT, but not in T-C or ALT. These results suggest that exposure to low-level TCE influences hepatic functions, affecting cholesterol metabolism rather than causing hepatic cell damage, and that these influences are subclinical and reversible. The increases in HDL-C caused by exposure to low-level TCE may be an example of "chemical hormesis" in humans.

Distribution of Trichloroethylene in Air, Soil and Groundwater around a Metalware Factory.

Concentrations of trichloroethylene (TCE) in air, soil and groundwater were measured around a metalware factory, where TCE was used for degreasing and cleaning of metalware. The mean level of TCE exhausted from the cleaning system through the stack at the factory was 360 ppm at the operating system or 130 ppm at the stand-by system, and was estimated to 30% of TCE used at the factory ; most residual of the used TCE (70%) was introduced into air through ventilators. TCE exhausted from the factory to the air was diluted rapidly, and TCE concentration in air decreased as the distance from the stack lengthened on the leeward. Some of TCE in air was supplied to soil within at least 400 m from the stack. TCE concentration in soil decreased as the distance from the stack lengthened. TCE concentration in groundwater from a well of 10 m depth located at the factory was 15000 μg/l at the average. cis-1, 2-Dichloroethylene, a product from TCE by biodegradation, were also detected in groundwater at 1700 μg/l at the average. TCE exhausted to the air distributed in air and soil, but this TCE did not cause groundwater contamination at the level of more than several mg/l.

Metabolism of trichloroethylene and tetrachloroethylene in human subjects.

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.

The Non-sensitized Photo-oxidation of Trichloroethylene in Air.

The Non-sensitized Photo-oxidation of Trichloroethylene in Air.

Determination of Trichloroethylene in Air

Abstract The sensitivity and accuracy of determination of trichloroethylene using the Fujiwara pyridine-alkali reaction has been improved. The procedure, as outlined, will detect one microgram of trichloroethylene in the aliquot analyzed and concentrations as low as one part per million by volume can be determined. The reproducibility of the method was found to be better than one-half of a microgram of trichloroethylene over the range of zero to 100 micrograms.

The Relation between Concentration of Trichloroethylene in Air and Quantity of Trichloro-acetic Acid in Urine

The Relation between Concentration of Trichloroethylene in Air and Quantity of Trichloro-acetic Acid in Urine

An indicator tube for the determination of trichloroethylene in air

An indicator tube for the determination of trichloroethylene in air

The estimation of trichloroethylene in air

The estimation of trichloroethylene in air