Concentration-time relationships for the effects of inhaled trichloroethylene on signal detection behavior in rats

The risk from inhaled volatile organic compounds (VOCs) is presently assessed on the basis of lifetime exposure to average concentrations of the vapor. This strategy yields rational predic-tions of risk if the product of concentration (C) and the duration of exposure (0 yields constant effects on health (Haber's Rule). The validity of this assumption was evaluated by assessing the acute behavioral effects of inhaled trichloroethylene (TCE) vapor at various values of C and t. Adult male Long-Evans rats (n = 11) were trained to perform a signal detection task in which a press on one lever produced food on trials containing a signal (a brief, unpredictable light flash); a press on a second lever produced food on trials lacking a signal. Response time (RT) and indices of sensitivity (SI) and bias (RT) derived from the theory of signal detection were calculated at three times during repeated daily 60-min tests conducted in air containing 0,400, 800,1200,1600, 2000