Salvini, M., Binaschi, S., and Riva, M. (1971).Brit. J. industr. Med.,28, 293-295. Evaluation of the psychophysiological functions in humans exposed to trichloroethylene. To provide data on the psychophysiological efficiency of human beings exposed to solvent vapour currently used in the industry the effects of trichloroethylene (TCE) were evaluated by exposing six male university students to an average vapour concentration of 110 p.p.m. for two s4-hour exposures, separated by a 1½-hour interval. Each subject was examined on two different days, on one day undertaking a set of tests in an atmosphere contaminated with TCE vapours and on another day in a `control' atmosphere which did not contain TCE. On each of the two days two sets of test were performed at 8.30 a.m. and at 6 p.m. The following tests were performed: perception test with tachistoscopic presentation, Wechsler Memory Scale, complex reaction time test, and manual dexterity test. A crossed scheme analysis was used. In all the tests performed a statistically very significant decrease in performance ability was seen; the greatest decrease occurred during the more complex tests. The suggested TLV for TCE (100 p.p.m) appears to be very close to the average concentration capable of interfering with psychophysiological efficiency, even in the absence of other undesirable subjective and objective manifestations.