[Teratogenicity study of N-methylphenyl-N'-methylphenyl-p-phenylenediamine (MMPD) in rats by oral administration].

Teratogenicity of N-methylphenyl-N'-methylphenyl-p-phenylenediamine (MMPD), a rubber antioxidant, was examined in Wistar rats. MMPD was given to pregnant rats by gavage once a day from day 6 through day 15 of pregnancy at doses of 0, 2, 4 and 8 mg/kg/day. The pregnant rats were sacrificed on day 20 of pregnancy and their fetuses were examined. MMPD was not maternal toxicity at any dose. MMPD did not affect growth or morphological development of fetuses. MMPD caused early embryonic death at 8 mg/kg. It was concluded from these results that the no-observed-adverse-effect level was 2 mg/kg/day for rat fetuses, and 8 mg/kg/day or higher for pregnant rats. The teratogenicity of MMPD was inconclusive due to its embryo-fetal lethality.