The studies to be conducted under this contract will evaluate the toxicity and carcinogenicity of p-nitrobenzoic acid administered in the diet for two years to male and female F344 rats and B6C3F1 mice. All moribund animals as well as those that survive to the end of the study will receive a complete gross examination. All grossly visible lesions and all tissues with non-neoplastic or neoplastic associated with chemicalo exposure lesions will receive a complete histopathologic examination.