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TRICHLOROETHYLENE anesthesia machil._-.11 Little trichloroethylene is used as an
<br /> anesthetic today.
<br /> CAS: 79-01-6 Vernon and Ferguson"' found that a 2-hour exposure of a volun-
<br /> r 1,3,2-Trichloroethylene; TCE teer to 1000 ppm of trichloroethylene resulted in adverse effects on
<br /> visual perception and motor skill;but 2-hour exposures at 300 ppm
<br /> CCI, — CHCI and 100 ppm produced no significant effect In a later report, the
<br /> TLV-TWA, 50 ppm ( = 270 mg/ml)* same authors" noted that low levels of alcohol in the blood (20-30
<br /> mg/100 ml) markedly augmented the effect of the 2-hour exposures
<br /> TLV-STEL, 200 ppm ( = 1080 mgW)t to trichloroethylene at concentrations of 300 and 1000 ppm.
<br /> The effects of trichloroethylene appear to be enhanced in some
<br /> Trichloroethylene is a colorless,nonflammable,mobile liquid with individuals by simultaneous exposure to caffeine,alcohol,and other
<br /> a sweetish odor resembling chloroform. Its physiochemical properties drugs. Degreasers Flush,a reddening of the skin, has been observed
<br /> include: in some subjects who ingest substantial quantities of alcohol after
<br /> Molecular weight 131.40 exposure to trichloroethylene. While disconcerting, this effect did
<br /> Specific gravity: 1.4649 at 20*C not appear to be injurious, since blood pressure and numerous other
<br /> Solidifies: —84.8°C parameters studied clinically were not affected.f81
<br /> Boiling point: 87°C Hepatic injury was observed in rats'91 exposed for two hours to a
<br /> Vapor pressure: 58 torr at 200C trichloroethylene concentration of 10,000 ppm when they were pre-
<br /> Vapor density: 4.53 (air-1) treated with phenobarbital, Aroclor 1254, hexachlorobenzene,
<br /> It is practically insoluble in water,but highly soluble in lipids. (Parti- 3-methyl cholanthrene, or pregneolone-1 6-alpha-carbonitrile. Liver
<br /> tion coefficients at 371C. blood-air 9, oil-air 940). In the presence of pathology appears associated with extensive metabolism of thchloro-
<br /> oxygen and heat or short ultraviolet wavelengths, trichloroethylene, ethylene.The major urinary excretion products in man are trichloro-
<br /> under certain circumstances, is decomposed to hydrochloric acid and acetic acid and trichloroethanol,the former being present for longer
<br /> phosgene. periods of time following exposure.
<br /> Trichloroethylene is used for vapor degreasing and as a solvent. Death in laboratory animals from acute exposure to trichloro-
<br /> In the past, trichloroethylene was used as an extractant in food- ethylene vapor results from respiratory failure or cardiac arrest10,71'
<br /> processing, but this was discontinued in 1975, when, on the basis Although trichloroethylene is reported to have direct action on the
<br /> of liver tumors in mice, the National Cancer Institute (NCI) issued bone marrow of rabbits causing myelotoxic anemia after 4-hour
<br /> an alert warning that trichloroethylene may be a carcinogen. It has repeated exposures, 6 days/week for 45 days to 2800 ppm,1721 other
<br /> limited use as a surgical anesthetic and analgesic. studies have failed to yield evidence of hematological effects in man
<br /> There is extensive, sometimes conflicting, literature on the toxi- or animals.
<br /> cology of trichloroethylene. Much of the old literature must be evalu- Adams et al exposed several species of animals 7 hours/day, 5
<br /> ated carefully, since the product then commercially available often day/week for approximately 6 months. At 3000 ppm by volume in
<br /> contained several percent of hepatotoxic ethane derivatives such as air, rats and rabbits showed an increase in liver and kidney weight.
<br /> 1,1,2,2-tetrachloroethane. This has been discussed by von Oet- At 400 ppm, rats showed an increase in liver and kidney weights
<br /> tengen."' and the male rats also showed significantly less growth. Guinea pigs
<br /> Organ systems reported to be effected by excessive exposure of had increased liver weights and the growth of the exposed males
<br /> man and animals to trichloroethylene are: 1) CNS (euphoria, anal- was less than controls. Rabbits showed a slight increase in liver
<br /> gesia,anesthesia); 2) liver(degeneration, hepatocellular carcinomas, weight. An exposed monkey showed no response to 400 ppm. At
<br /> mice only); 3) kidney (degeneration); 4) lung (tachypnea); 5) heart 200 ppm,the only effect was depressed growth in guinea pigs. Rats,
<br /> (arrhythmias); and 6) skin (irritation, vesication; paralysis of fingers rabbits, and monkeys showed no response. At a concentration of
<br /> when immersed in liquid trichloroethylene).Of these effects,the limit 100 ppm,none of the species showed any significant response.The
<br /> ing factor in decreasing the exposure is depression of the central maximum concentrations without effect for the 6-month period were
<br /> nervous system. as follows: monkeys,400 ppm; rats and rabbits,200 ppm,and guinea
<br /> Trichloroethylene is moderate to low in acute toxicity with an acute pigs, 100 ppm.�l"
<br /> oral LD50 of 6000-7000 mg/kg reported in rats, dogs, cats, and Prendergast et a/"" exposed rats, guinea pigs, dogs, rabbits, and
<br /> rabbits.123 It has a typical solvent effect on topical application. Con- monkeys 24 hours/day for 90 days to 35 ppm with no effect except
<br /> tact with the liquid causes pain but no permanent injury in the eyes slight growth depression. Repeated 8-hour daily exposures to 700
<br /> and defats the skin causing topical dermatitis.Although it is absorbed ppm for 90 days were also without effect.
<br /> through the skin, dermal absorption is not likely to be significant if Ahlmark and Forssman151 estimated exposure to trichloroethylene
<br /> dermatitis is prevented."' by measuring the urinary excretion of trichloroacetic acid.They found
<br /> The knowledge of acute human toxicity of trichloroethylene comes the chief symptoms to be abnormal fatigue, irritability, headache,
<br /> mainly from its use as an anesthetic."' Tachypnea and ventricular gastric disturbances, and intolerance to alcohol. Ahlmark and
<br /> arrhythmias are equated with overexposure(inhaled concentrations Friberg161 tentatively suggested 30 ppm vapor as a desirable limit for
<br /> greater than 15,000 ppm). Systemic toxicity has been low foilowing the time-weighted average occupational exposure, based on urinary
<br /> anesthesia, but occasionally hepatotoxicity has been reported,gener- trichloroacetic acid levels. Although trichloroacetic acid levels are
<br /> ally attributed to breakdown of the trichloroethylene to dichloro- indicative of average exposures,they do not necessarily describe ex-
<br /> acetylene and phosgene by soda-lime present in some recirculatory cursions which may have been responsible for the observed
<br /> symptoms.
<br /> - 'TWA value adopted in 98z. Haas"" and Grandjean et al"B' reported a variety of nervous dis-
<br /> t STEL adopted in 1984. turbances in a group of 50 workers exposed to trichloroethvlene vapor
<br /> 595
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