Developmental toxicity following oral administration of a high-boiling coal liquid to pregnant rats

Heavy distillate (HD), the highest‐boiling coal liquid from the solvent‐refined coal‐II process (SRC‐II), was administered by intragastric (IG) intubation to pregnant rats. Five dose levels of HD (0.09, 0.14, 0.18, 0.36 and 0.74 g kg−1), were given daily from 12 to 16 days of gestation and the rats were killed at 20 days of gestation. Maternal body weights and weights of the liver, kidneys, spleen, adrenals, thymus, ovaries and the gravid uterus were obtained. Gravid uteri were evaluated for prenatal mortality. Live fetuses were examined for malformations and weighed; fetal lungs were excised and weighed. Maternal (extragestational) weight gains and thymic weights diminished in all groups that received the SRC material. Adrenal weights were increased in all treated animals, except for those in the lowest‐dose group (0.9 g kg−1). There was significant maternal mortality at 0.74 g kg−1 and increased intrauterine mortality at doses of 0.37 and 0.74 g kg−1. Placental weight was depressed, and the incidence of fetal anomalies was increased at 0.14 g kg−1 and all higher dose levels.