Short-term toxicity of methyl amyl ketone in rats

Methyl amyl ketone was given to rats, by oral intubation in oil solution, at dose levels of 0 (control), 20, 100 or 500 mg/kg/day for 13 wk. There were no statistically significant differences between treated and control rats in the rate of body-weight gain, food or water consumption, haematological findings, or the results of renal concentration tests. The histological appearance of the tissues was unaffected by treatment. Ketone bodies were found in the urine of a few male rats given 20 mg/kg methyl amyl ketone but this was thought to be due to excretion of the unchanged compound. At 500 mg/kg/day, the liver weight was increased in both sexes and the kidney weight in males only. Some slight increases were also seen at the 100 mg/kg/day level. The excretion of cells in the urine was increased at the 100 and 500 mg/kg/day levels. A mammary adenocarcinoma developed in a female rat given 20 mg/kg/day but this was not thought to be associated with the treatment. The no-untoward-effect level established in this study was 20 mg methyl amyl ketone/kg body weight/day, a level approximately 100 times the estimated maximum likely intake in man.