Learning impairments following postnatal exposure to benzene.

Two groups of male hooded rats of the Sprague-Dawley strain were administered 550 mg/kg of benzene in corn oil or pure corn oil on Days 9, 11, and 13 postpartum. When tested on problems of the Hebb-Williams closed-field maze-learning task, the rats previously exposed to benzene manifest significantly impaired learning ability when compared to control rats in the total number of error zones entered over the 12 test problems. No significant differences were found in food consumption, water consumption, or weight gain. Moreover, none of the overt manifestations characteristic of acute or chronic benzene exposure were observed. Learning deficits were exhibited at levels of exposure previously considered subtoxic.