Trichloroethylene analysis

Bois FY. Statistical analysis of Clewell et al. PBPK model of trichloroethylene kinetics. Environ Health Perspect 2000 May 108 Suppl 2 307-16. 

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. 

A retrospective case-control study conducted in humans compared spontaneous abortion rates among women who had been exposed occupationally or nonoccupationally to trichloroethylene and other solvents to rates among women without solvent exposure (Windham et al. 1991). The authors observed approximately three times the risk of spontaneous abortion with exposure to trichloroethylene. This risk increased further when women with less than a half hour of exposure to trichloroethylene each week were excluded from the analysis. However, a consistent dose-response relationship was not observed, and most of the women were exposed to a variety of solvents, not just trichloroethylene. 

An analysis of the EPA STORET Data Base (1980-1982) found that trichloroethylene had been positively detected in 28% of 9,295 surface water reporting stations nationwide (Staples et al. 1985). An analysis of 1,350 samples taken from 1978 to 1979 and 4,972 samples from 1980 to 1981 from the Ohio River system found a similar percentage of positive detections most positive samples had trichloroethylene levels of... 

An analysis of six municipal solid waste samples from Hamburg, Germany, revealed levels of trichloroethylene ranging from undetectable to 0.59 mg/kg (Deipser and Stegmaim 1994). In a study analyzing automobile exhaust for chlorinated compounds, trichloroethylene was not detected (Hasanen et al. 1979). 

The purpose of this chapter is to describe the analytical methods that are available for detecting, measuring, and/or monitoring trichloroethylene, its metabolites, and other biomarkers of exposure and effect to trichloroethylene. The intent is not to provide an exhaustive list of analytical methods. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used for environmental samples are the methods approved by federal agencies and organizations such as EPA and the National Institute for Occupational Safety and Health (NIOSH). Other methods presented in this chapter are those that are approved by groups such as the Association of Official Analytical Chemists (AOAC) and the American Public Health Association (APHA). Additionally, analytical methods may be included that modify previously used methods to obtain lower detection limits and/or to improve accuracy and precision. 

Several methods are available for the analysis of trichloroethylene in biological media. The method of choice depends on the nature of the sample matrix cost of analysis required precision, accuracy, and detection limit and turnaround time of the method. The main analytical method used to analyze for the presence of trichloroethylene and its metabolites, trichloroethanol and TCA, in biological samples is separation by gas chromatography (GC) combined with detection by mass spectrometry (MS) or electron capture detection (ECD). Trichloroethylene and/or its metabolites have been detected in exhaled air, blood, urine, breast milk, and tissues. Details on sample preparation, analytical method, and sensitivity and accuracy of selected methods are provided in Table 6-1. 

Purge-and-trap methods have also been used to analyze biological fluids for the presence of trichloroethylene. Breast milk and blood were analyzed for trichloroethylene by purging onto a Tenax gas chromatograph to concentrate the volatiles, followed by thermal desorption and analysis by GC/MS (Antoine et al. 1986 Pellizzari et al. 1982). However, the breast milk analysis was only qualitative, and recoveries appeared to be low for those chemicals analyzed (Pellizzari et al. 1982). Precision (Antoine et al. 1986) and sensitivity (Pellizzari et al. 1982) were comparable to headspace analysis. 

Headspace analysis has also been used to determine trichloroethylene in water samples. High accuracy and excellent precision were reported when GC/ECD was used to analyze headspace gases over water (Dietz and Singley 1979). Direct injection of water into a portable GC suitable for field use employed an ultraviolet detector (Motwani et al. 1986). While detection was comparable to the more common methods (low ppb), recovery was very low. Solid waste leachates from sanitary landfills have been analyzed for trichloroethylene and other volatile organic compounds (Schultz and Kjeldsen 1986). Detection limits for the procedure, which involves extraction with pentane followed by GC/MS analysis, are in the low-ppb and low-ppm ranges for concentrated and unconcentrated samples, respectively. Accuracy and precision data were not reported. 

Analysis of soils and sediments is typically performed with aqueous extraction followed by headspace analysis or the purge-and-trap methods described above. Comparison of these two methods has found them equally suited for on-site analysis of soils (Hewitt et al. 1992). The major limitation of headspace analysis has been incomplete desorption of trichloroethylene from the soil matrix, although this was shown to be alleviated by methanol extraction (Pavlostathis and Mathavan 1992). 

The Environmental Health Laboratory Sciences Division of the National Center for Environmental Health, Centers for Disease Control and Prevention, is developing methods for the analysis of trichloroethylene and other volatile organic compounds in blood. These methods use purge and trap methodology, high resolution... 

Boekhold AJ, Van der Schee HA, Kaandorp BH. 1989. [Rapid gas-chromatographic determination of trichloroethylene and/or tetrachloroethylene in lettuce by direct headspace analysis.] Z Lebensm Unters Forsch 189 550-553. (German)... 

BogenKT. 1988. Pharmacokinetics for regulatory risk analysis The case of trichloroethylene. Regul Toxicol Pharmacol 8 447-466. 

Burg JE, Gist GL, Allred SL, et al. 1995. The national exposure registry - morbidity analysis of noncancer outcomes from the trichloroethylene subregistry baseline data. International Journal of Occupational Medicine and Toxicology 4 237-257. 

Cronin WJ, Oswald EJ, Shelley ML, et al. 1995. A trichloroethylene risk assessment using a Monte Carlo analysis of parameter uncertainty in conjunction with physiologically-based pharmacokinetic modeling. Risk Anal 15 555-565. 

Stewart RD, Hake CL, Peterson JE. 1974b. Use of breath analysis to monitor trichloroethylene exposures. Arch Environ Health 29 6-13. 

Vesterberg, 0, Astrand 1. 1976. Exposure to trichloroethylene monitored by analysis of metabolites in blood and urine. J Occup Med 18 224. 

Hewitt, A. D., 1999, Measurement for Trichloroethylene Relationship between Soil Vapor and Soil Matrix Environmental Testing and Analysis, May/June, Vol. 8, No. 3, pp. 25-31. 

After omitting the 10 L data, the data were resubjected to a principal component analysis. The loadings of the two new principal components were compared with those from the previous analysis. The omission of the 10 L data caused a separation of benzaldehyde and toluene from the previously clustered compounds as well as retaining the separation of benzene and trichloroethylene as found previously. 

A cost analysis was performed in 1991 for a solar detoxification system at Livermore, California, capable of processing an average of 4.4 liters/sec of water with a peak flow of 30 liters/sec. The system would be processing water containing 400 parts per billion (ppb) trichloroethylene to a treated concentration of 5 ppb. Costs were estimated at 16.00 per 1000 gal. Data from the field test using a one-sun mode of operation reduced the estimated cost to roughly 7.00/gal (D12953N, p. 203). 

Blair et al. (1998) performed a retrospective cohort mortality study of 14 457 workers employed for at least one year between 1952 and 1956 at an aircraft maintenance facility in the United States. Among this cohort were 6737 workers who had been exposed to carbon tetrachloride (Stewart et al., 1991). The methods used for this study are described in greater detail in the monograph on dichloromethane. An extensive exposure assessment was performed to classify exposure to trichloroethylene quantitatively and to classify exposure (ever/never) to other chemicals qualitatively (Stewart et al., 1991). Risks from chemicals other than trichloroethylene w ere examined in a Poisson regression analysis of cancer incidence data. Among women, exposure to carbon tetrachloride was associated with an increased risk of non-Hodgkin lymphoma (relative risk (RR), 3.3 95% CI,... 

CHLOROCARBONSANDCHLOROHYDROCARBONS - TRICHLOROETHYLENE] (Vol 6) -analysis by optical spectroscopy [SPECTROSCOPY, OPTICAL] (Vol 22)... 

Degradation of aqueous trichloroethylene was followed by the determination of ionic chloride. Chloroform was identified as a minor product through GC analysis. The fact that no 02 was consumed during the degradation of TCE suggests that TCE, not 02, is the principal electron trap. The low reactivity of TCE in aqueous solution may be due to a strong interaction between adsorbed TCE and liquid water. 

Many of the private laboratories offer screening for heavy metals (including lead, mercury, cadmium, arsenic, aluminum, and nickel) and other chemicals, such as PCBs, chlorinated solvents, trichloroethylene, and pesticides. One such laboratory advertised testing for nearly 70 chemicals. Occupational screening was also offered at some of the laboratories. For many laboratories, people may order test and screening kits over the Internet, by fax, or by telephone. A person can send in a blood, urine, or hair sample for analysis. In some cases, a physician s signature is required to have the sample tested. 

Solvents are typically not targeted for biomonitoring in general population studies, because their rapid clearance by exhalation or metabolism results in a transient biomarker that does not reach steady state. However, analysis of such rapidly cleared chemicals may be possible, as exemplified in a trichloroethylene (TCE) biomarker study (Sohn et al. 2004), which constitutes another case study of pharmacokinetic modeling of human biomonitoring data under non-steady-state conditions. 

The loss of VOCs from soil during sampling, shipping, storage, and even during analysis itself is a well-documented problem. For example, when exposed to air at room temperature, a soil sample will experience a 100 percent reduction in the trichloroethylene concentration within 1 hour (Flewitt 1996). 

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