1,1,1-Trichloroethane in drinking-water: Previous page | 1,2,3,4,5,6,7,8,9,10,11

Kinetics and metabolism in laboratory animals and humans

Contents Preface Acknowledgements Acronyms and abbreviations used in the text General description Environmental levels and human exposure Kinetics and metabolism in laboratory animals and humans Effects on laboratory animals and in vitro test systems Effects on humans Conclusions References Disclaimer

1,1,1-Trichloroethane appears to be absorbed rapidly and completely from the lungs of human subjects (11). After 4 h of continuous exposure to 378 or 756 mg/m3, a steady-state lung retention of 30% was observed (12,13). The concentration of 1,1,1-trichloroethane in the expired air of humans after ingestion of 0.6 g/kg of body weight was equivalent to the expired air concentration following an inhalation exposure of 2700 mg/m3 (14).

After inhalation by humans, blood levels of 1,1,1-trichloroethane were highly correlated with alveolar air levels. Within 2 h of exposure, 60–80% was eliminated from the blood (12). One day after intraperitoneal administration of 1,1,1-trichloroethane at 700 mg/kg of body weight, rats retained 0.9% (as the parent compound) in the skin, 0.02% in the blood, 0.02% in the fat and 0.1% in other sites (15).

1,1,1-Trichloroethane is metabolized to a very limited extent in mammals (12); the proportion is probably less than 6% in humans. Metabolites include trichloroethanol, trichloroethane glucuronide and trichloroethanoic acid. Less than 3% of a single intraperitoneal injection of 1,1,1-trichloroethane was metabolized by rats (15). The metabolic fate of inhaled 1,1,1-trichloroethane in rats and mice was not altered on repeated exposure (16).

1,1,1-Trichloroethane was detected in the expired air of human subjects exposed to oral doses (14). Metabolites were excreted primarily in urine; very small amounts of trichloroethanol (1%) were excreted by the lungs (12). Over 99% of intraperitoneally injected 1,1,1-trichloroethane was excreted by rats via the pulmonary route (98.7% unchanged); less than 1% was excreted via the urine, primarily as the trichloroethanol glucuronide (15). Rats and mice exposed via inhalation to radiolabelled 1,1,1-trichloroethane for 6 h excreted more than 96% of the administered radioactivity during the first 24 h, primarily via exhalation (16).

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