© 1989 Oxford University Press
research-article |
Inhalation Developmental Toxicity Study of Propylene Oxide in Fischer 344 Rats1



*The Stephen B. Harris Group, Lo Mesa California 92042
International Research and Development Corporation Mattawan, Michigan 49071
ARCO Chemical Company Newtown Square, Pennsylvania 19073
Received October 31, 1988; accepted January 25, 1989
The developmental toxicity potential of propylene oxide (PO) was evaluated in Fischer 344 rats following inhalation exposure. Four groups of 25 mated female rats were exposed to 0, 100, 300, and 500 ppm of PO for 6 hr per day on Gestation Days 6 through 15, inclusive. Cesarean sections were performed on all females on Gestation Day 20 and the fetuses removed for morphological evaluation. Exposure to propylene oxide did not adversely affect survival, appearance, or behavior at any of the exposure levels tested. Maternal body weight gain and food consumption were reduced significantly among the females at the 500 ppm level during the exposure period. No exposure-related effects were noted with respect to maternal water consumption, organ weights, cesarean section, or fetal morphological observations with the sole exception of increased frequency of seventh cervical ribs in fetuses at the maternally toxic exposure level of 500 ppm. In summation, the no-observable-adverse-effect level (NOAEL) of propylene oxide. when administered to Fischer 344 rats via whole-body inhalation exposure, was considered to be 300 ppm.