Teratogenic effects were evaluated in rats and rabbits following inhalation exposure to ethylene-oxide (75218), propylene-oxide (75569), and n-butyl-acetate (123864). Animals were exposed to test vapors within specially constructed stainless steel chambers designed to maintain uniform concentrations under controlled environmental conditions. Inhalation exposures were done 7 hours per day to 150 parts per million (ppm) ethylene-oxide, 500ppm propylene-oxide, or 1500ppm n-butyl-acetate. Artificially inseminated rabbits were subjected to one of the following exposure regimens for each chemical: filtered air (control), or chemical exposure from days 1 through 19 of gestation. Rats were exposed to filtered air (control), chemical exposure from days 7 through 16 of gestation, chemical exposure from days 1 through 16 of gestation, or chemical exposure 5 days per week for 3 weeks prior to mating, and daily from days 1 through 16 of gestation. Necropsies were done on rats at day 21 of gestation and on rabbits at 30 days of gestation. Pregnant animals were examined for toxic changes including histopathology and reproductive and teratogenic effects. In rabbits, ethylene-oxide produced no evidence of maternal toxicity, embryotoxicity or teratogenicity. In rats, fetal size was reduced and ossification of the skull was seen. Increased numbers of resorptions were observed in rabbit litters exposed to propylene- oxide from days 1 through 19 of gestation, but no fetal anomalies were found. In rats, propylene-oxide produced reproductive effects such as decreased corpora lutea, implantation sites per dam, and live fetuses per litter. The percentage of resorbed implantation sites was highest in rats exposed to propylene-oxide from days 7 through 16 of gestation. N-butyl-acetate produced no effects on reproductive performance in rabbits, but fetal effects observed included increased incidences of retinal folds, and other morphological variations in litters. In rats, increased incidences of fetal rib deformities were observed, but no teratogenic effects were found following n-butyl-acetate exposure.
NIOSH, U.S. Department of Health and Human Services, Cincinnati, Ohio