Metabolism and excretion of trichloroacetic acid as a metabolite of trichloroethylene in human subjects and rabbits

The concentration of chloral hydrate (CH) and trichloroacetic acid (TCA) in the serum and urine in human subjects and rabbits were determioned after inhalation exposure to trichloroethylene (TRI). CH was detected only in the urine of the limited cases in both human subjects and rabbits the first day after TRI exposure, while not detected in the blood in all cases. TCA was detected in the serum and urine throughout more than a week after TRI exposure, while became undetectable in the urine earlier than in the blood. The pharmacokinetics of TCA administered in the blood of the rabbits were similar to that observed after TRIexposure. The total amounts of TCA excreted in the urine were only less than 20% of the administered doses.　A decrease in TCA concentration and an increase in chlorine (Cl) concentration were seen in the TCA solution which was incubated at 37℃ after rabbit liver homogenate was added. Furthermore, an increased Cl excretion in the urine of rabbits was observed after intravenous administration of TCA. The results mentioned above indicate that Cl is a major metabolite of TCA.