Induction of prenatal toxicity in the rat by diethylstilbestrol, zeranol, 3,4,3',4',-tetrachlorobiphenyl, cadmium, and lead.

A teratological study was conducted in pregnant Sprague-Dawley rats dosed orally with diethylstilbestrol (DES), zeranol (ZN), 3,3',4,4'-tetrachlorobiphenyl (4CB), cadmium, or lead on days 6-18 of gestation. Fetuses were examined on day 19 for growth retardation, resorption, gross malformations, and organ-level anomalies. Synthesis of protein, DNA, and proteoglycan in fetal limb cartilage was also studied by measuring the incorporation of labeled precursors in vitro. DES, ZN, and 4CB produced a dose-dependent increase in embryolethality. Treatment with DES caused an increase in cryptorchidism and edema, and reduced average fetal weight. Zeranol also decreased fetal weight, but was not teratogenic nor did it alter rates of synthesis of macromolecules in cartilage. 4CB caused severe intestinal lesions that were associated with accumulation of blood in the digestive tract and amniotic fluid. 4CB also decreased overall fetal size and total and ossified tibia lengths. Cadmium produced no malformations although incorporation of [3H]amino acids by limb cartilage was slightly increased. Lead was not teratogenic.