The objective of this project is to characterize dose-response relationships and toxicity of acetone administered by dosed water to rats and mice in 14-day repeated-dose and 90-day subchronic studies. At the end of each study, all animals will be given gross and microscopic histopathologic evaluations. Hematology and sperm morphology/vaginal cytology will be performed in the 90-day study. The results of the 14-day study will be used by NTP to establish doses to be used in the 90-day study, and results of the 90-day study will be used for setting doses for a possible chronic study. (If a chronic study is to be conducted, it will be performed under a separate contract.