CD-1 mice were exposed to baseline
gasoline vapor condensate (BGVC) alone or to vapors of
gasoline blended with methyl tertiary butyl
ether (G/
MTBE). Inhalation exposures were 6h/d on GD 5-17 at levels of 0, 2000, 10,000, and 20,000mg/m(3). Dams were evaluated for evidence of maternal toxicity, and fetuses were weighed, sexed, and evaluated for external, visceral, and skeletal anomalies. Exposure to 20,000mg/m(3) of BGVC produced slight reductions in maternal
body weight/gain and decreased
fetal body weight. G/
MTBE exposure did not produce statistically significant maternal or developmental effects; however, two uncommon ventral wall closure defects occurred:
gastroschisis (1 fetus
at 10,000mg/m(3)) and
ectopia cordis (1 fetus at 2000mg/m(3); 2 fetuses/1 litter
at 10,000mg/m(3)). A second study (G/
MTBE-2) evaluated similar exposure levels on GD 5-16 and an additional group exposed to 30,000mg/m(3) from GD 5-10. An increased incidence of
cleft palate was observed at 30,000mg/m(3) G/
MTBE. No
ectopia cordis occurred in the replicate study, but a single observation of
gastroschisis was observed at 30,000mg/m(3). The no observed adverse effect levels for maternal/developmental toxicity in the BGVC study were 10,000/2000mg/m(3), 20,000/20,000 for the G/
MTBE study, and 10,000/20,000 for the G/
MTBE-2 study.