Studies on the Prenatal Toxicity of 3-Methyl-1-butanol and 2-Methyl-1-propanol in Rats and Rabbits Following Inhalation Exposure

3-Methyl-1-butanol (MEB) and 2-methyl-1-propanol (MEP) weretested for their prenatal inhalation toxicity in pregnant Wistarrats or Himalayan rabbits. Twenty-five female rats and 15 femalerabbits per group were exposed to MEB and MEP vapors at concentrationsof 10, 2.5, or 0.5 mg/liter, 6 hr/day. The rats were exposedon Days 6–15 postcoitum (pc) and the rabbits were exposedon Days 7–19 postinsemination (pi). Control groups wereexposed to clean air. The body weights of the animals of eitherspecies were determined several times throughout the studies.All rats and all rabbits were killed on Day 20 pc and Day 29pi, respectively. The fetuses were removed from the uterus andexamined for compound-related effects. The high concentrationof 10 mg/liter caused a slight retardation of body weight gainin the dams of either species exposed to MEB and in the damsof rabbits exposed to MEP during the first days of the exposureperiod. Eye irritation was observed only in the MEB-treatedrabbits during the period of exposure to 10 mg/liter. The fetusesof either species exhibited no signs of embryo-/fetotoxicityor teratogenic effects caused by MEP or MEB. Under the experimentalconditions, 2.5 mg/liter was found to be a no-observable-adverse-effectlevel (NOAEL) for the dams of either species exposed to MEBand for the does exposed to MEP, whereas 10 mg/liter MEP wasthe NOAEL for the maternal rats. For both substances 10 mg/literwas defined as the NOAEL for the conceptuses of either species.