Short-term toxicity study in rats dosed with menthone.

Menthone, a component of peppermint oil, was given p.o. to groups of 10 male and 10 female rats at dose levels of 0, 200, 400 and 800 mg/kg b.w./day, respectively, for 28 days. After 19 days the dose was reduced to 400 mg/kg b.w. in the female group receiving the highest dose. Analyses of plasma showed a dose-dependent decrease in creatinine content and a dose-dependent increase in alkaline phosphatase activity and bilirubin. The relative weights of liver and spleen were increased. Cyst-like spaces were seen histopathologically in the white matter of the cerebellum of the two highest dose groups. The no-effect level for menthone in this study was lower than 200 mg/kg b.w./day.