Despite similar ACTH responses to UCO, the cortisol response was greater in the LTH fetuses than in normoxic controls. LTH appears to result in enhanced adrenal sensitivity to a secondary stressor or altered cortisol metabolism.

Ikeda, M., Ohtsuji, H., Imamura, T., and Komoike, Y. (1972).Brit. J. industr. Med.,29, 328-333. Urinary excretion of total trichloro-compounds, trichloroethanol, and trichloroacetic acid as a measure of exposure to trichloroethylene and tetrachloroethylene. To investigate the relation between trichloroethylene and tetrachloroethylene concentrations in working environments and metabolite concentrations in urine, a series of surveys was conducted at 17 workshops where the vapour concentration in the air of each workshop was relatively constant. Urine samples collected from 85 male workers were analysed for total trichloro-compounds (TTC), and trichloroacetic acid (TCA). Trichloroethanol (TCE) was estimated by difference. Statistical analyses of the data revealed that the urinary concentrations of both TTC and TCE were proportional to the atmospheric concentration of trichloroethylene. The concentration of TCA was also related to the vapour concentration up to 50 p.p.m. but not at higher concentrations. Further calculations suggested that only one-third of the trichloroethylene absorbed through the lungs was excreted in the urine during working time. In tetrachloroethylene exposure, urinary metabolite levels increased until the atmospheric concentration of the solvent reached 50 to 100 p.p.m., but little increase occurred at higher concentration. This observation was further confirmed by experimental exposure of rats. The toxicological significance of changes in the metabolism of the two solvents is discussed in relation to the possible necessity of reducing the threshold limit value from the current value of 100 p.p.m.

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