Chronic lead exposure of rats: open-field performance.

Three groups of male hooded rats were chronically exposed to lead in the acetate form prenatally, as well as postnatally via the dam's milk and in the drinking water, at concentrations of 0 ppm, 19 ppm, and 38 ppm for 35 days. No significant differences were found in weight gain, although significant increases in food consumption were noted in animals receiving 19 ppm lead acetate and increased ingestion of lead acetate in animals receiving 19 ppm and 38 ppm. When subjects were tested in an open-field task, no significant differences were found in emotionality, the number of squares traversed, frequency and duration of rearing, or in frequency of grooming. However, subjects receiving 38 ppm lead displayed a significant reduction in duration of grooming when compared to animals receiving either 19 ppm or 0 ppm. The results suggest that prenatal lead exposure, followed by postnatal exposure, may affect some elements of activity, while having little effect on others.

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.