Health assessment of gasoline and fuel oxygenate vapors: Developmental toxicity in mice

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 6 h/d on GD 5-17 at levels of 0, 2000, 10,000, and 20,000 mg/m3. Dams were evaluated for evidence of maternal toxicity, and fetuses were weighed, sexed, and evaluated for external, visceral, and skeletal anomalies. Exposure to 20,000 mg/m3 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 10,000 mg/m3) and ectopia cordis (1 fetus at 2000 mg/m3; 2 fetuses/1 litter at 10,000 mg/m3). A second study (G/MTBE-2) evaluated similar exposure levels on GD 5-16 and an additional group exposed to 30,000 mg/m3 from GD 5-10. An increased incidence of cleft palate was observed at 30,000 mg/m3 G/MTBE. No ectopia cordis occurred in the replicate study, but a single observation of gastroschisis was observed at 30,000 mg/m3. The no observed adverse effect levels for maternal/developmental toxicity in the BGVC study were 10,000/2000 mg/m3, 20,000/20,000 for the G/MTBE study, and 10,000/20,000 for the G/MTBE-2 study.