Tetrachloroethylene, case study

Several case studies provide some information on concentrations of tetrachloroethylene in various tissues following inhalation exposure. In one hiunan fatality following exposure to the chemical, the highest... 

Travis CC, White RK, Arms AD. 1989. A physiologically based pharmacokinetic approach for assessing the cancer risk of tetrachloroethylene. In Paustenbach DJ ed. The Risk Assessment of Environmental and Human Health Hazards A Textbook of Case Studies. John Wiley Sons, New York 769-796. 

Biotransformation was also strongly indicated as a factor in the degradation of trichloroethylene in a case of soil and groundwater pollution (Milde et al. 1988). The only ethylenes at the point source of pollution were tetrachloroethylene and trichloroethylene however, substantial amounts of known metabolites of these two compounds (dichloroethylene, vinyl chloride, and ethylene) were found at points far from the source. Data from laboratory studies by the same group supported the study authors contention that degradation was due... 

Doherty RE (2000a) A history of the production and use of carbon tetrachloride, tetrachloroethyl-ene, trichloroethylene and 1,1,1-trichloroethane in the United States. Part 2. Trichloroethylene and 1,1,1-trichloroethane J Environ Forensics 1 83-93 Doherty RE (2000b) A history of the production and use of carbon tetrachloride, tetrachloroethylene, trichloroethylene and 1,1,1-trichloroethane in the United States Part 1. Historical background carbon tetrachloride and tetrachloroethylene. J Environ Forensics 1 69-81 Dorsch MM, Scragg RK, McMichael AJ, Baghurst PA, Dyer KF (1984) Congenital malformations and maternal drinking water supply in rural South Australia A case-control study. Am J Epidemiol 119 473-86... 

Occupational illness and injury187 cost 30-40 billion dollars/yr in the United States.188 In 1994 there were 6.8 million injuries and illnesses in private industry, amounting to 8.4 cases per 100 workers. Nearly two-thirds were disorders associated with repeated trauma, such as carpal tunnel syndrome.189 The Occupational Safety and Health Act of 1970 set up the National Institute Safety and Health (NIOSH) to study the problem and the Occupational Safety and Health Administration (OSHA) to deal with it through inspections and regulations. Both have received so much criticism of their effectiveness that they are struggling to find more effective ways to deal with the problem.190 NIOSH is searching for practical ways to protect workers, especially those in small businesses from methylene chloride, tetrachloroethylene, diesel exhaust in coal mines, isocyanates, 2-methoxyethanol, and others. OSHA is about to expand a plan that worked well in Maine, a state that used to have one of the worst accident and illness records in the United States.191 The 200 firms with the worst records were asked to look for deficiencies and to correct them. They were also inspected. These measures cut injuries and illnesses over a 2-year period. 

In addition to gases produced naturally in the environment, estuaries tend to be enriched in byproducts of industry and other human activity. A few studies have investigated volatile organic pollutants such as chlorinated hydrocarbons (chloroform, tet-rachloromethane, 1,1-dichloroethane, 1,2-dichlor-oethane, 1,1,1-trichloroethane, trichloroethylene and tetrachloroethylene) and monocyclic aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-xylene and m- and p-xylene). Concentrations of VOCs are controlled primarily by the location of the sources, dilution of river water with clean marine water within the estuary, gas exchange, and in some cases, adsorption onto suspended or settling solids. In some cases (for example, chloroform) there also may be natural biotic sources of the gas. Volatilization to the atmosphere can be an important cleansing mechanism for the estuary system. Since the only estuaries studied to date are heavily impacted by human activity (the Elbe and... 

In a study of Finnish workers (292 men and 557 women) exposed primarily to tetrachloroethylene, nonsignificant increases in non-Hodgkin s lymphoma, cervical cancer, and pancreatic cancer were noted (Anttila et al. 1995). The total number of cancer cases in this study was 31. Blood concentrations of tetrachloroethylene measured in random samples taken from these workers averaged 116 pg/L in men and 66 pg/L in women. As the biological exposure index associated with an 8-hour exposure of 25 ppm is 500 pg/L tetrachloroethylene in blood (ACGIH 1995), these workers were probably exposed to concentrations of tetrachloroethylene below 25 ppm. 

A case-control study in New Jersey identified an increased risk of primary liver cancer in male woikers categorized as craftsman or operators in laundry or dry cleaning operations (Stemhagen et al. 1983). The specific solvents to which the woikers were exposed and exposure levels were not identified. The study controlled for alcohol consumption and smoking. A case control study of astrocytic brain cancer among white males in Louisiana, New Jersey, and Pennsylvania showed a trend for increased brain tumors with high tetrachloroethylene exposure (Heineman et al. 1994). This result was based on only three cases and is limited in that exposure information was not available. This study may also be confounded by exposure to methylene chloride. The study authors concluded that the association between tetrachloroethylene and brain cancer requires further study. 

There was, however, a study suggesting immunological effects in humans with chronic exposure to a solvent-contaminated domestic water supply. Several wells in Woburn, Massachusetts, were contaminated by a variety of solvents. The two main volatile chlorinated hydrocarbons measured before well closure were trichloroethylene (267 ppb) and tetrachloroethylene (21 ppb) (Byers et al. 1988). A potential association between water contamination in Woburn and cases of childhood leukemia is discussed in Section 2.2.2.8. 

The only study of the excretion of tetrachloroethylene and metabolites following oral exposure in humans is a case report of a 6-year-old boy who accidentally ingested 8-10 mL of pure tetrachloroethylene (Koppel et al. 1985). The bulk of the ingested tetrachloroethylene was exhaled unchanged however, this was not under normal conditions since the patient was h erventilated to facilitate pulmonary elimination of the compound. Tetrachloroethylene, TCA, and trichloroethanol were detected and quantified in the urine. Total urinary tetrachloroethylene decreased from 30 pg on day 1 of treatment to 3 pg on day 3. Total urinary trichloro-compounds increased from 8 mg on day 1 to 68 mg on day 3. 

An additional study did not reveal any effects on neurological function among 14 persons who lived above or next to dry cleaning facilities for 1-30 years compared to 23 controls matched for age ( 1 year, in two cases 3 and 5 years) and gender when the absolute values of the tests were examined (Altmann et al. 1995). Median tetrachloroethylene exposure concentrations were 0.2 ppm in the apartments of the exposed individuals and 0.0003 ppm in the apartments of control subjects, and blood concentrations were 17.8 46.9 pg/L in exposed individuals and less than the detection limit of 0.5 pg/L in the controls. When multivariate analysis was completed to adjust for age, gender, and education, an increased response time in a continuous performance test (p<0.05), increased simple reaction time to a visual stimuli (p<0.05), and decreased performance in a test of visual memory (p<0.05) were observed. No effect on pattern reversal visual-evoked potentials was... 

An intermediate-duration inhalation MRL was not derived. The only available intermediate-duration human studies were two case reports (Abedin et al. 1980 Meckler and Phelps 1966) and a case control study of reproductive outcome in women occupationally exposed (Ahlborg 1990) that did not identify exposure concentrations. Minimal changes in flash-evoked potential were observed in rats exposed to 800 ppm tetrachloroethylene 6 hours/day, 5 days/week, for 13 weeks, with no effects at 200 ppm (Mattsson et al. 1992). The testing was completed 1 week after the end of exposure. A study in mice (Kjellstrand et al. 

Cardiovascular Effects. Despite the relatively large number of people occupationally exposed to tetrachloroethylene, there are few reported cases of tetrachloroethylene-associated cardiotoxicity. Cardiac arrhythmias in a small number of Woburn residents cannot be directly related to chronic tetrachloroethylene exposure (Byers et al. 1988). Experimental exposure studies have not found changes in electrocardiograms for persons exposed at concentrations up to 100 ppm for 5.5 hours, 5 days/week (Stewart et al. 1977) or up to 150 ppm for 7.5 hours/day, 5 days/week, for 1 week (Stewart et al. 1981). 

Figure 3.16 is an electron micrograph of crystals of polyetliylene obtained by cooling a dilute solution (0.1%, in tetrachloroethylene). Such electron microscopy and diffraction studies have confirmed not only the lamellar nature of single crystals but have also revealed that the polymer molecules are oriented normal (or, in some cases, very nearly normal) to the lamellar surface. 

Schwetz et al." exposed rats and mice to 300 ppm tetrachloroethylene for 7 h/day on days 6-15 of pregnancy. The dams were killed just before term and the fetuses examined by acceptable teratological methods but results are given on a per litter basis only. The number of treated animals in each case was 17 and the number of controls (air exposed) 3 0 for both rat and mouse studies. 

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