Fetal distribution of styrene in rats after vapor phase exposures.

Pregnant rats were subjected to a 5-hour exposure of either 2,000 or 1,000 ppm atmospheres of styrene. Concentrations of styrene in the maternal blood and in each fetus were measured. The fetal concentrations in the 2,000 ppm exposure group were significantly more than double that in the 1,000 ppm group. Fetal weight and distribution of styrene appear to be related to the fetal position on the uterine horn. Those at the ovarian and cervical ends of the uterine horn were of lowest weight and those at the ovarian end had the highest concentration of styrene. Concentrations of styrene appeared to be much lower in the fetuses than in maternal organs and tissues after similar exposures.