1,1,1-TRICHLOROETHANE
Toxic encephalopathy was found in a study of 28 workers who had developed chronic symptoms
including impaired short-term memory, decreased ability to concentrate, impaired balance and
mood alterations following exposure to 1,1,1-tricholorethane.1 Many also reported headaches,
fatigue and sleep disturbance. Some of them exhibited abnormal balance on Romberg and/or heelto-toe walking. Quantitative Romberg testing, also known as posturography, was abnormal in
84.6%. Neurocognitive testing was abnormal in the group showing numerous impairments
including decreased ability to focus and maintain attention and concentration, impaired short term
and intermediate memory processing and impaired motor speed. The balance disturbance was felt
to involve vestibular neuropathy. Disturbances found in the ocular and somatosensory
components indicated brain damage in these pathways. The authors concluded that the prognosis
for recovery was poor.1
Sleep apnea was also demonstrated with a pilot study of an individual exposed approximately 20
hours per week. This individual had increased SGOT and LDH and also developed central sleep
apnea, a probable involvement of the brain stem. Other symptoms included fatigue, weakness,
unsteady balance and irritability.2 1,1,1-tricholorethane can accumulate in body fat even with
intermittent exposure according to an animal inhalation study. This study also demonstrated
impairment in brain RNA (which would affect brain biochemistry) and reduce the detoxification
capability of the liver known as the cytochrome p450 system.3 Severe changes in animal
inhalation studies have been found with exposures of 210 ppm and even short-term exposure to
humans at 350 ppm has been shown to impair brain function.4
A U.S. government review of the medical literature on this compound describes human health
effects as involving the brain, induction of fatigue, lightheadedness and impaired balance,
impaired cognitive functioning on neurocognitive testing, damage to the liver, and dizziness in
workers accompanied by fatigue and changes in balance testing. The document also confirms that
a one-hour exposure to an adhesive resulted in altered liver function and dizziness.5
Further evidence of liver disease includes an individual who developed fibrosis of the liver
following exposure to 1,1,1-tricholorethane for several hours daily for about four years. This
individual had the classic enzyme elevation pattern that was typical of nonalcohol-induced liver
disease with greater elevation of SGPT than SGOT and had an alcohol consumption history of one
beer per month.6 Other studies of humans and animals have confirmed that repeated exposure
causes liver toxicity confirmed by biopsy showing elevated liver enzymes or a pattern typical of
nonalcohol-induced liver effects (more elevation of SGPT/ALT than SGOT/AST). All were
confirmed by biopsy showing fatty deposition and liver changes of cellular infiltrate. The enzyme
gamma-glutamyltransferase was also elevated in two of the four individuals.7
Toxic
encephalopathy, fatty liver disease, and psychiatric changes are all effects reported from chronic
exposure to 1,1,1-tricholorethane on the hazardous substances database used by the poison control
centers.
1
Kelafant, G., Berg, R., and Schleenbaker, R., "Toxic encephalopathy due to 1,1,1-Trichloroethane exposure," American Journal Industrial
Medicine, 25:439-446, 1994.
1,1,1-Trichloroethane
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7
Wiess, M. "Trichloroethane (TCE) and Central Sleep Apnea: a Case Study," Journal Toxicology Industrial Health, 11:101-104, 1983.
Savolainen, H, et al. "Trichloroethylene and 1,1,1-Trichloroethane: Effects on Brain and Liver After Five Days Intermittent Inhalation,”
Archives Toxicology , 38:229-237, 1977.
Rosengren, L, etal. "Astrogliosis in the Cerebral Cortex of Gerbils After Long-term Exposure to 1,1,1-Trichloroethane," Scandinavian Journal
Work, Environment Health," 11:447-455, 1985.
NIOSH Criteria for Recommended Standard: Occupational Exposure to 1,1,1-Trichloroethane (methyl chloroform), U.S. Department of Health,
Education and Welfare. NIOSH publication 76-184, 1976.
Cohen, C. and Frank, A. "Liver disease following occupational exposure to 1,1,1-Trichloroethane: a case report," American
Journal of Industrial Medicine, 26:237-241, 1994.
Hodgson, M., Heyl, A. and Van Thiel, D. "Liver disease associated with exposure to 1,1,1-Trichloroethane," Archives
Internal Medicine, 149:1793-1798, 1989.