Study on the role of maternal sex steroid production and metabolism in the embryotoxicity of para-xylene.

CFY rats were exposed to inhalation of clean air or air containing para-xylene (3000 mg/m3) on the 10th, and 9th and 10th days of gestation. Uterine and ovarian venous blood flow, fetal weight, ovarian progesterone and 17 beta-oestradiol secretion, and the progesterone and 17 beta-oestradiol level of peripheral blood (uterine and femoral veins) were measured on the 11th day of gestation. Exposure to para-xylene decreased the weight of the fetuses and the progesterone and 17 beta-oestradiol levels of peripheral blood, but it did not influence the uterine and ovarian venous outflow and the ovarian progesterone and 17 beta-oestradiol secretion rate. It is concluded that para-xylene, by inducing the hepatic monooxygenase system, facilitates the biotransformation of progesterone and 17 beta-oestradiol, which is metabolized by this enzyme system. The decrease in the sex hormone level of peripheral blood is supposed to play a role in the embryotoxicity (retarding and lethal effects) of para-xylene.