| Abstract |
Pregnant CD-1 mice were exposed to 1,000, 2,000, 5,000, 7,500, 10,000, or 15,000 ppm on methanol for 7 hr/day on days 6-15 of gestation. On day 17 of gestation, remaining mice were weighed, killed and the gravid uterus was removed. Numbers of implantation sites, live and dead fetuses and resorptions were counted, and fetuses were examined externally and weighed as a litter. Significant increases in the incidence of exencephaly and cleft palate were observed at 5,000 ppm and above, increased postimplantation mortality at 7,500 ppm and above (including an increasing incidence of full-litter resorption), and reduced fetal weight at 10,000 ppm and above. A dose-related increase in cervical ribs or ossification sites lateral to the seventh cervical vertebra was significant at 2,000 ppm and above. Thus, the NOAEL for the developmental toxicity in this study is 1,000 ppm. The results of this study indicate that inhaled methanol is developmentally toxic in the mouse at exposure levels which were not maternally toxic. Litters of pregnant mice gavaged orally with 4 g methanol/kg displayed developmental toxic effects similar to those seen in the 10,000 ppm methanol exposure group. (Copyright (c) 1993 Wiley-Liss, Inc.) |
