A method for repeated evaluation of benzene uptake in rats and mice during a six hour inhalation period

Benzene uptake measurements and respiratory minute volume (RMV) were assessed in rats and mice during a 6-hour inhalation exposure to 300 ppm (v/v) of benzene vapor. The values for benzene uptake and RMV were used to compare predictions of inhaled dose in both species. The theoretical prediction assumed an unchanging RMV. The next prediction allowed adjustments for changes in RMV during exposure. The final prediction addressed benzene uptake directly. The uptake characteristics of benzene in both species were different from the theoretical prediction, from the prediction adjusted for changing RMV and from each other. The greatest difference was seen in rats where the observed benzene dose was only 28% of the theoretical value. The experiment was not designed to elucidate the causes for the difference between the predictions, nor was the data sufficient to suggest whether the rat or the mouse was a suitable model of benzene uptake in humans.