Postnatal evaluation of prenatal exposure to p-xylene in the rat

What is it about?

Developmental exposures during pregnancy to p-xylene in rats. Dams were allowed to give birth, and litters were counted, weighed, and observed for external malformations on postnatal days (PD) 1 and 3. Litters were normalized to 8 pups (4 males and 4 females ± 1) on PD4. On PD21 animals were weaned and littermates housed by sex. Body weights were recorded weekly until weaning and once every 2 weeks thereafter. Central nervous system (CNS) development was evaluated by acoustic startle response on PD13, 17, 21, and 63 as well as figure-8 maze activity on PD22 and 65. Maternal weight gain during the treatment period was significantly less in the high-dose group. No effects were seen on litter size or weight at birth or on PD3.

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Why is it important?

There were no effects of xylene exposure on growth rate. There were no treatment-related effects on acoustic startle response or figure-8 maze activity. Thus, p-xylene as administered in this study does not appear to be a selective developmental toxicant in the rat.