Evaluation of oral exposure to Polnoks R for female rats in developmental toxicity studies

This study was performed to evaluate the effects of prenatal development of rats exposed to Polnoks R, an antioxidant in elastomer processing. Pregnant female rats were exposed to Polnoks R by gavage every day on days 6-15 of gestation at doses of 170, 340, and 670 mg/kg body weight (b,w) (6%, 13%, and 25% LD50). Clinical observations, maternal body weights, and food and water consumption were recorded throughout gestation. At scheduled necropsy on 20 day of gestation maternal animals were evaluated for body weight, liver, spleen, ovarjan kidney, and adrenal weights, number of ovarian corpora lutea, and status of uterine implantation sites. Fetuses were counted, weighed, and examined for external, skeletal, and visceral alterations. Maternal weight gain was reduced in the group receiving Polnoks R at the 670 mg/ kg dose. In all groups the daily food and water consumptions were similar to controls. The relative weights of the adrenals, ovaries, spleen, and liver of the females intoxicated with the highest dose of Polnoks R were significantly higher than control organs. Polnoks R is an embryotoxic and fetotoxic agent. It produced a significant increase in the average number of postimplantation losses and a decrease in both the weight and body length of the fetuses from the pregnant female rats exposed to the highest dose. This chemical also produced birth defects-absent or short tail, cleft palate, and internal hydrocephalus-but only at doses toxic to the mother.