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For a better understanding of absorption, distribution, excretion, and metabolism of trichloroethylene the time-course of blood concentration of the vapour and urinary excretion of its metabolites was examined using a pharmacokinetic model. After a single experimental exposure in which four men inhaled 100 parts per million (ppm) of trichloroethylene for four hours an elimination curve showed three exponential components, that is, x = 1 005e-16.71t + 0.449e-1. 710t + 0.255e-0.2027t, where x is the blood concentration in mg/l and t the time in hours from 0 to 10. The overall rate constant for the disappearance of trichloroethylene was found to agree with the theoretical one, estimated by means of a mathematical model for the blood concentration data. A D.O-XD plot, developed from a mathematical model for urinary excretion, could also give a good estimate of rate constants for the transfer of trichloroethylene in the body. The rate constant thus estimated from urinary excretion was consistent with data on the blood concentration.As industrial exposure to trichloroethylene vapour is liable to vary, air analysis does not necessarily give a real indication of the true exposure. A quantitative index of a worker's exposure can be estimated according to the amount of trichloroethylene being absorbed in his body (Roach, 1966;Elkins, 1967). Monitoring trichloroethylene levels in blood or expired air and measuring urinary metabolites of trichloroethylene are currently the most common techniques for determining the body burden of the vapour (Ahlmark and Forssman, 1951;Stewart et al., 1962Stewart et al., ,1970Stewart et al., ,1974Morgan et al., 1970;Nomiyama, 1971 chronic exposure, which is a common situation in a work place (Sato and Nakajima, 1977).In the current study a mathematical model was developed to simulate the processes of absorption, distribution, excretion, and metabolism of trichloroethylene, the rate constants for each process being estimated from the time-course data of the vapour concentration in blood and the urinary excretion of its metabolites. Experiments SOLUBILITY OF TRICHLOROETHYLENE IN TISSUES OF RATSThe blood/air and tissue/blood partition coefficients were determined according to the method of Sato et al. (1974) with minor modifications. Tissue excised from a freshly killed rat was stripped of capsular and vascular connective tissues and weighed. The tissue was then homogenised with a known volume of 0-9 % saline. Five vials of equal size, each 16-5 ml on average and containing 1 ml of the tissue homogenates, were used as test vessels. 0-1 ml of a trichloroethylene solution in saline containing 10 ,ll/l was put into the vials on which rubber and aluminium-foil stoppers were placed as quickly as

In order to clarify the expression of cytochrome P450 and glutathione S-transferase in human esophagus, 41 samples of human esophagus with squamous-cell carcinoma were investigated by immunoblot analysis and enzyme assays. Cytochrome P450 1A2/1 was clearly expressed in microsomes, and the amount in samples with tumorous tissue was significantly greater than that in samples without tumourous tissues or in liver; cytochrome P450 2B6 and 3A4/3 were expressed polymorphically. Aryl hydrocarbon hydroxylase activity was detected in microsomes and was greater in samples from smokers than non-smokers. Patients who both smoked and drank alcohol, however, had activity similar to that of patients without these habits. Glutathione S-transferase M1 and A1/2 protein existed polymorphically in cytosol, and glutathione S-transferase P1-1 was detected in all samples. The frequency of expression of the glutathione S-transferase A1/2 protein was greater in patients with M1 protein than in those without; no difference in the expression was seen for glutathione S-transferase P1-1. Neither smoking nor drinking influenced the expression or activity of glutathione S-transferase. Our data support the idea that some carcinogens can be directly activated or inactivated in human esophageal epithelium.

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The simultaneous gas-chromatographic separation of a mixture of 14 lower fatty acids, 11 phenols and 7 indoles was performed by using a fused silica glass capillary column of Carbowax 20M (50m x 0.2mm i.d., Carbowax 2OM deactivated). Complete separation of the mixture was obtained, except for the peaks of phenols and o-cresol, o-ethylphenol and 3,5-xylenol and pelargonic acid, 2,3-xylenol and 1,2-dirnethylindole, whose peaks overlapped, and 2-and 3-methylindoles, which were poorly separated. The optimum conditions are as follows: column temperature, held for 1 min a t 100 "C; column oven, heated a t 4 "C min-1 from 100 to 220 "C, maintained at 220 "C for 9 min for standard compounds or 29 min for sample specimens, then cooled to 100 "C; and carrier gas (nitrogen) flow-rate, 0.97 ml min-l. The method was applied to the analysis of the lower fatty acids, phenols and indoles in cat and human faeces and non-smoker saliva.