Prenatal toxicity of inhalation exposure to 2-methoxypropanol-1 in rabbits.

2-Methoxypropanol-1 was investigated for prenatal toxicity in Himalayan rabbits after inhalation exposure to 0, 145, 225, 350, and 545 ppm for 6 hr per day from Gestation Day 6 through 18. Maternally toxic effects were found with decreased body weights from Day 12 of gestation through the end of the study at 545 ppm. A dose-dependent increase of resorptions, fetal malformations, and variations was observed at 225, 350, and 545 ppm, whereas 145 ppm was devoid of exposure-related effects. The malformation rate at 545 ppm was 100%. The types of malformations mainly consisted of absent phalanges and absent or rudimentary metatarsal bones, malformed ribs, and a unique enlargement of sternebrae. The effects are very similar to those previously found with 2-methoxypropyl-acetate-1. The results of this study may have implications for the quantitative estimation of risks associated with 2-methoxy-propanol-1 impurities in the widely used isomer 1-methoxypropanol-2 which itself does not show developmental toxicity.