This contract involves the evaluation of the toxic and carcinogenic potential of selected chemicals in laboratory animals. Exposure to these chemicals is via oral administration. The project includes 2-year studies of methacrylonitrile, acrylonitrile, benzophenone, 2-hydroxy-4- methoxybenzophenone, dichlorodiphenylsulfone, dipropylene glycol, and 90- day and 2-year studies of elmiron. Studies for each chemical are divided into phases, with phase 1 efforts including prestart activities including bulk chemical reanalysis, dose formulation and analysis method validation, and biological sample analysis method validation. Acceptable prestart reports must be received before permission is granted to proceed to subsequent phases.