Trichloroethylene experimental

Liang C, Bruell CJ (2008) Thermally activated persulfate oxidation of trichloroethylene Experimental investigation of reaction orders. Ind Eng Chem Res 47(9) 2912-2918... 

Animal experimentation has revealed inhaled concentrations that result in death following acute, intermediate, and chronic exposure. An LC50 value for acute exposure in rats was reported as 12,500 ppm for a 4-hour exposure (Siegel et al. 1971). Two out of 10 mice died after a 4-hour exposure to 6,400 ppm trichloroethylene (Kylin et al. 1962). Death was often caused by the central nervous system depression that... 

Dermal Effects. Humans that were experimentally exposed to 200 ppm of trichloroethylene vapor for 7 hours experienced dry throats (40% of the subjects), begiiming after 30 minutes (Stewart et al. 1970). The subjects experiencing these symptoms did not experience them when exposed in the same manner on 5 other consecutive days. These effects are presumed to be due to direct contact with the vapor. Skin irritation and rashes have resulted from occupational exposure to trichloroethylene (Bauer and Rabens 1974 El Ghawabi et al. 1973). The dermal effects are usually the consequence of direct skin contact with concentrated solutions, but occupational exposure also involves vapor contact. Adverse effects have not been reported from exposure to dilute aqueous solutions. 

Experimental exposure studies have attempted to associate various neurological effects in humans with specific trichloroethylene exposure levels. Voluntary exposures of 1 hours resulted in complaints of drowsiness at 27 ppm and headache at 81 ppm (Nomiyama and Nomiyama 1977). These are very low exposure levels, but the results are questionable because of the use of only three test subjects per dose, lack of statistical analysis, sporadic occurrence of the effects, lack of clear dose-response relationships, and discrepancies between the text and summary table in the report. Therefore, this study is not presented in Table 2-1. No effects on visual perception, two-point discrimination, blood pressure, pulse rate, or respiration rate were observed at any vapor concentration in this study. Other neurobehavioral tests were not performed, and the subjects were not evaluated following exposure. 

This section will describe clinical practice and research concerning methods for reducing toxic effects of exposure to trichloroethylene. However, because some of the treatments discussed may be experimental and unproven, this section should not be used as a guide for treatment of exposures to trichloroethylene. When specific exposures have occurred, poison control centers and medical toxicologists should be consulted for medical advice. The following texts provide specific information about treatment following exposures to trichloroethylene Bronstein and Currance 1988 Ellenhom and Barceloux 1988 Stutz and Janusz 1988. 

Comparative Toxicokinetics. In humans, the targets for trichloroethylene toxicity are the liver, kidney, cardiovascular system, and nervous system. Experimental animal studies support this conclusion, although the susceptibilities of some targets, such as the liver, appear to differ between rats and mice. The fact that these two species could exhibit such different effects allows us to question which species is an appropriate model for humans. A similar situation occurred in the cancer studies, where results in rats and mice had different outcomes. The critical issue appears to be differences in metabolism of trichloroethylene across species (Andersen et al. 1980 Buben and O Flaherty 1985 Filser and Bolt 1979 Prout et al. 1985 Stott et al. 1982). Further studies relating the metabolism of humans to those of rats and mice are needed to confirm the basis for differences in species and sex susceptibility to trichloroethylene s toxic effects and in estimating human heath effects from animal data. Development and validation of PBPK models is one approach to interspecies comparisons of data. 

Trichloroethylene has been detected in a number of rainwater samples collected in the United States and elsewhere (see Section 5.4.2). It is moderately soluble in water, and experimental data have shown that scavenging by rainwater occurs rapidly (Jung et al. 1992). Trichloroethylene can, however, be expected to revolatilize back to the atmosphere after being deposited by wet deposition. Evaporation from dry surfaces can also be predicted from the high vapor pressure. 

The Henry s law constant value of 2.Ox 10 atm-m /mol at 20°C suggests that trichloroethylene partitions rapidly to the atmosphere from surface water. The major route of removal of trichloroethylene from water is volatilization (EPA 1985c). Laboratory studies have demonstrated that trichloroethylene volatilizes rapidly from water (Chodola et al. 1989 Dilling 1977 Okouchi 1986 Roberts and Dandliker 1983). Dilling et al. (1975) reported the experimental half-life with respect to volatilization of 1 mg/L trichloroethylene from water to be an average of 21 minutes at approximately 25 °C in an open container. Although volatilization is rapid, actual volatilization rates are dependent upon temperature, water movement and depth, associated air movement, and other factors. A mathematical model based on Pick s diffusion law has been developed to describe trichloroethylene volatilization from quiescent water, and the rate constant was found to be inversely proportional to the square of the water depth (Peng et al. 1994). 

Experimentally measured bioconcentration factors (BCFs), which provide an indication of the tendency of a chemical to partition to the fatty tissue of organisms, have been found to range between 10 and 100 for trichloroethylene in fish (Kawasaki 1980 Kenaga 1980 Neely et al. 1974 Veith et al. 1980). Barrows et al. (1980) estimated a value of 17 for bluegill sunfish. Somewhat lower BCFs were determined by Saisho et al. (1994) for blue mussel (4.52) and killifish (2.71). These numbers are suggestive of a low tendency to bioaccumulate. 

Physical and Chemical Properties. The physical and chemical properties of trichloroethylene are well characterized (HSDB 1994 McNeill 1979 Windholz 1983) and allow prediction of the environmental fate of the compound. Estimates based on available constants are generally in good agreement with experimentally determined values. No additional studies are required at this time. 

Baker AB. 1958. The nervous system in trichloroethylene. An experimental study. J Neuropath Exp Med 17 649-655. 

KonietzkoH. 1979. [Health damage due to trichloroethylene An epidemiological and experimental clinical study.] Fortscritte der Medisin 97(14) 671-679. (German)... 

Maltoni C, Lefemine G, Cotti G. 1986. Experimental research on trichloroethylene carcinogenesis. In Maltoni C, Mehlman MA, eds. Archives of research on industrial carcinogenesis series. Vol. V. Princeton, NJ Princeton Scientific Publishing Co., Inc., 393. 

Mazza V, Brancaccio A. 1967. [Characteristics of the formed elements of the blood and bone marrow in experimental trichloroethylene intoxication.] Folia Med 50 318-324. (Italian)... 

McKone TE, Knezovich JP. 1991. The transfer of trichloroethylene (TCE) from a shower to indoor air experimental measurements and their implications. J Air Waste Manag Assoc 41 832-837. 

Prendergast JA, Jones RA, Jenkins LJ Jr, et al. 1967. Effects on experimental animals of long-term inhalation of trichloroethylene, carbon tetrachloride, 1,1,1-trichloroethane, dichlorodifluoromethane, and 1,1-dichloroethylene. Toxicol Appl Pharmacol 10 270-289. 

Stewart RD, Dodd HC, Gay HH, et al. 1970. Experimental human exposure to trichloroethylene. Arch Environ Health 20 64-71. 

Experimental design Six humans (sex unspecified) were exposed to 200 ppm trichloroethylene for 5 days, 7 hours/day in a confined chamber. Previous experiments had shown no effects at lower concentrations. No controls were used in this study. 

Experimental design Groups of 12 male NMRI mouse pups were treated by gavage with 0, 50, or 290 mg/kg/day trichloroethylene in a 20% peanut oil emulsion. The pups were treated for 7 days begiiming at 10 days of age. The doses selected did not sedate the mice. At 17 and 60 days of age behavior was tested. The tests were performed between 8 am-12 pm. Locomotion, rearing, and total activity were measured in an automated device with high and low level infrared beams. 

Zhong et al. (2003) studied the apparent solubility of trichloroethylene in aqueous solutions, where the experimental variables were surfactant type and cosolvent concentration. The surfactants used in the experiment were sodium dihexyl sulfo-succinte (MA-80), sodium dodecyl sulfate (SDS), polyoxyethylene 20 (POE 20), sorbitan monooleate (Tween 80), and a mixture of Surfonic- PE2597 and Witconol-NPIOO. Isopropanol was used as the alcohol cosolvent. Eigure 8.20 shows the results of a batch experiment studying the effects of type and concentration of surfactant on solubilization of trichloroethylene in aqueous solutions. A correlation between surfactant chain length and solubilization rate may explain this behavior. However, the solubilization rate constants decrease with surfactant concentration. Addition of the cosolvent isopropanol to MA-80 increased the solubility of isopropanol at each surfactant concentration but did not demonstrate any particular trend in solubilization rate of isopropanol for the other surfactants tested. In the case of anionic surfactants (MA-80 and SDS), the solubility and solubilization rate increase with increasing electrolyte concentration for all surfactant concentrations. 

Toxicology. Trichloroethylene (TCE) is primarily a central nervous system (CNS) depressant. Although it is carcinogenic at high doses in experimental animals, it is not considered to be a human carcinogen at low exposure levels. 

Chang, W.-K., and C. S. Criddle, Experimental evaluation of a model for cometabolism Prediction of simultaneous degradation of trichloroethylene and methane by a methanotrophic mixed culture , Biotech. Bioeng., 56,492-501 (1997). 

Example 5c) Assuming no experimental values of Kow or S are available, estimate Koc for trichloroethylene from MCIs, using the following expression (Meylan et al. 1992) ... 

The idea of using fluidized bed as both uniform light distribution and an immobilizing support for photocatalysts has been originally proposed and theoretically evaluated by Yue and Khan [3]. Experimental application of this idea has been demonstrated by Dibble and Raupp [4] who designed a bench scale flat plate fluidized bed photoreactor for photocatalytic oxidation of trichloroethylene (TCE). Recently, Lim et al. [5,6] have developed a modified two-dimensional fluidized bed photocatalytic reactor system and determined the effects of various operating variables on decomposition of NO. Fluidized bed photocatalytic reactor systems have several advantages over conventional immobilized or slurry-type photocatalytic reactors [7,8]. The unique reac-... 

Trichloroethylene has caused liver carcinoma in experimental animals and is a suspect human carcinogen, although a recent review of the literature has concluded that it would be wholly inappropriate to classify trichloroethylene as a human carcinogen. 8 Numerous body organs are... 

Pedit et al. [226] used a kinetic model for the scale-up of ozone/hydrogen peroxide oxidation of some volatile organochlorine compounds such as trichloroethylene and tetrachloroethylene. The kinetic model was applied to simulate the ozone/hydrogen peroxide treatment of these pollutants in a full-scale demonstration plant of the Los Angeles Department of Water and Power. The authors confirmed from the model that the reaction rate of the pollutant with ozone was several orders of magnitude lower than that with the hydroxyl radical. When considering that the natural organic matter acts as a promoter of hydroxyl radicals, the ozone utilization prediction was 81.2%, very close to the actual 88.4% experimentally observed. 

Gotpagar JK, Grulke EA, Bhattacharayya D. Reductive dehalogenation of trichloroethylene kinetic models and experimental verification. J Hazard Mater 1998 62 243-264. 

Chrysikopoulos CV, Lee KY, Harmon TC (2000) Dissolution of a well-defined trichloroethylene pool in saturated porous media experimental design and aquifer characterization. Water Resour Res 36 1687-1696... 

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