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<br /> METHYL CHLOROFORM Methyl chloroform not produce teratogenic effects in rats or
<br /> mice exposed 7 hours per day to 875 ppm during the period of
<br /> CAS: 71-55-6 organogenisis.10' Two lifetime cancer studies have been negative.
<br /> There were no adverse effects of any kind in rats exposed 6 hours
<br /> 1,1,1-Trichloroethane per day for 12 months to either 875 or 1750 ppm vapors.""Groups
<br /> CH,CCI, of rats and mice fed methyl chloroform by gavage in the National
<br /> Cancer Institute (NCI) Bioassay Program showed no increase in
<br /> TLV-TWA, 350 ppm ( = 1900 mg/ml) tumors over that of the controls.12'The dosage levels fed were 1500
<br /> TLV-STEL, 450 ppm ( = 2450 mg/ml and 750 g/kg/day.
<br /> Industrial experience has been consistent with the findings in
<br /> Methyl chloroform is a water-clear, nonflammable liquid. Its physio- laboratory animals."I Deaths due to anesthesia and/or cardiac sen-
<br /> chemical properties include: sitization have been reported to have occurred in poorly ventilated
<br /> Molecular weight 133.42 rooms, pits, tanks and other small areas."'31 Removal of uncons-
<br /> Specific gravity: 1.3376 at 20°C cious individuals has generally resulted in rapid and complete
<br /> Solidifies: -32.5°C recovery.
<br /> Boiling point: 74.1°C In a few test subjects beginning anesthetic effects occur at con-
<br /> Vapor pressure: 100 torr at 20°C centrations approaching 500 ppm.""' The most extensive study of
<br /> It burns only in excess oxygen or in air if a strong source of ignition neurological response has been by Stewart and associates who re-
<br /> is present. It is almost insoluble in water, but is miscible with most ported that
<br /> organic solvents. repetitive vapor exposure to. . .350 ppm produced no un
<br /> The major usage of methyl"chloroform is as a cleaning solvent. toward subjective or objective health response. . .'115)
<br /> Because of its reactivity with magnesium,aluminum and their alloys, Some female test subjects did object slightly to the odor at this con-
<br /> inhibitors are generally added to increase the stability of the solvent. centration. In practice, odor is not a problem until exposure con-
<br /> The oral toxicity of methyl chloroform is low. The LD50 for rats, centrations approach 500 ppm.""
<br /> mice, rabbits and guinea pigs was reported to range from 5.7 to 12.3 The most extensive study of industrially exposed workers has been
<br /> g/kg.j1' Like many solvents, methyl chloroform will defat the skin, reported by Kramer and associates who conducted an epidemio-
<br /> causing redness and scaliness.Absorption through the skin can occur logical study on 151 men and women exposed for several months
<br /> but is not a significant route of toxic exposure; the acute LD50 for to six years to methyl chloroform.j" During the study period ex-
<br /> rabbits is greater than 16 g/kg.When doses of 0.5 g/kg were applied posures for some workers exceeded 200 ppm. Based on subjective
<br /> repeatedly for 90 days to rabbits, no effects were caused except for responses and some previous monitoring data,exposure concentra-
<br /> slight reversible irritation of the skin at the site of application."' tions had been higher prior to study period. When compared to 151
<br /> While comparatively low in systemic toxicity, methyl chloroform matched pair control subjects by numerous medical and physiolog-
<br /> is an anesthetic and is capable of causing death when inhaled at con- ical parameters, there were no adverse effects related to exposure.
<br /> centrations in excess of 14,000-15,000 ppm."' A time-weighted average TLV for methyl chloroform of 350 ppm
<br /> Torke15on and associates"' described the toxicity of methyl chlo- is recommended to prevent beginning anesthetic effects and objec-
<br /> roform from repeated exposures of animals. Exposure of animals for tions to odor. A STEL of 450 ppm is recommended for protection
<br /> three months at concentrations from 1000 to 10,000 ppm caused against anesthesia.
<br /> some pathologic changes in the livers and lungs of some species; Other recommendations: West Germany (1974) 200 ppm; East
<br /> the main effect of exposure appeared to be anesthesia. Exposure to Germany (1973) 90 ppm; Sweden (197 8) 70 ppm; USSR (1972)
<br /> the vapor at 500 ppm for seven hours a day, five days a week for 4 ppm; Czechoslovakia (1969) 90 ppm.
<br /> six months did not cause any toxic changes of significance in rats,
<br /> guinea pigs, rabbits or monkeys.
<br /> Rowe and associatesi21 found that the only effect of repeated ex- References
<br /> posure of several species at 500 ppm of a mixture containing 75% 1. Torkelson, -r.R. et al: Am. Ind. Hyg. Assoc. 1. 19:353 (1958).
<br /> methyl chloroform and 25% perch loroethylene was a slight degres- 2. Rowe, V.K. et al: Ibid. 24:541 (1963).
<br /> cion in the growth of guinea pigs, due to a reduced food intake. At 3. Gehring, P.I.: Tox. Appl. Pharm. 13:287 (1968).
<br /> 1000 ppm mild, reversible liver and kidney changes were detected.
<br /> A time-weighted average limit of 400 ppm was recommended for 4. Plaa,G.L, E.A Evans and C.H.Hine:J.Pharm. Expel. Therap. 123:224
<br /> this mixture. (1958).
<br /> 5. Rennick, B.R. et all: Fed. Proc. 8:327 (1949).
<br /> Other animal studies confirm the low hepatotoxicity of methyl chlo- 6. Trochimowicz, H.J. et al:lOM 18:26 (1976).
<br /> roform,"-" but indicates that cardiac sensitization can occur if ex-
<br /> posures are excessive.","' Studies in dogs given intravenous 7. Aviado, D.M. et all: Methyl Chloroform and Trichloroethylene in the
<br /> Environment. Clinical Rubber Press, Cleveland, OH (1976),
<br /> injections of epinephrine in conjunction with exposure to either 2500, 8. Dornette, W.H. and J.P. tones:Anesth. Analg. 39:249 (1966).
<br /> 5000 or 10,000 ppm vapor have been described. Under these ex-
<br /> aggerated conditions, no cardiac sensitization was observed at 2500 9• Hake, C.L et al: Arch. Env. Health 1:101 (1966).
<br /> ppm, but 3 of 18 dogs at 5000 ppm and 12 of 12 at 10,000 ppm 10. Schwetz, B.A. et al: TAP 32:84 (1975).
<br /> were affected.161 Other studies in rabbits, rats and mice, as well as 11. NIOSH:Criteria fora Recommended Standard-Occupational Exposure
<br /> human experience in anesthesiology, confirm the cardiac effects of to 1,1,1-Trichloroethane. DHEW Pub. No. (NIOSH) 76-184 (1976).
<br /> methyl chloroform.17.11 Methyl chloroform is poorly metabolized and 12. Weisberger, E.. Env. Health Perspectives 21:7 (1977).
<br /> is excreted unchanged in the expired air of animals and human test 13. Patty,F.A.:Industrial Hygiene and Toxicology,2nd ed.,Vol. Il,p. 1288.
<br /> subjects.," Interscience, New York (1963).
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