C-9, R-7, TB Sulfate, or TB Sulfonate were administered to rats by gavage at 100, 300, 250, or 500 mg/kg body weight/day, respectively, from Days 6 through 15 of gestation to determine the degree of hazard to the developing conceptus. The dosage of TB Sulfate given was lethal to six of the seven rate tested, and the rat that survived did not yield live fetuses at term. Therefore, its potential hazard to the conceptus was not assessed. The remaining chemicals were tested at levels that were less toxic to the dams. None of the test chemicals were demonstrated to represent a unique hazard to the maintenance of pregnancy or to the developing conceptus.