Initial Submission: Cinch Herbicide (sd 95481) Teratology Study in Sprague Dawley Rats (final Report) with Attachments and Cover Letter dated 030592.

摘要

7-Oxabicyclo[2.2.1]heptane, 1-methyl-4-(1-methylethyl)- 2-[(2-methylphenyl)methoxy]-, exo(.+-.)-, also known as Cinch Herbicide (CAS# 87818-31-3), was evaluated for embryo/fetal toxicity in Charles River Sprague Dawley rats. The test substance was administered by oral gavage to 25 female pregnant rats per group at doses of 0, 0.03, 0.30, 1.00, and 2.00 g/Kg/day on days 6 through 15 of gestation. Two dams in the high dose group died on day 15 of gestation which at necropsy, exhibited enlarged livers and decreased spleen size as well as lesions in the stomach which was also filled with a brown or yellow-orange fluid. Adverse clinical effects were observed in all dose groups excluding the control. These effects consisted of excess salivation, chromorrhinorrhea, thin appearance, decreased motor activity, exudate from the vagina, excess lacrimation, and soft or liquid feces. Body weight gain was also decreased in all dose groups. Statistically and biologically significant fetal toxicity only occurred in the high dose group. These effects consisted of decreased fetal body weights, increased incidence of dilation of the lateral ventricles of the brain, and delayed ossification of caudal vertebrae and metacarpals. Fetal effects in other dose groups were attributed to maternal toxicity. No maternal NOEL was reported, the fetal NOEL was 1.00 g/Kg/day.