Linear models of risk assessment may be appropriate for chemical that are initiators of carcinogenesis while threshold model of risk assessment have been proposed for promoters. The proper risk assessment model for the regulation of promoters of carcinogenesis remains an active area of research and controversy. Cancer is a multistage process (e.g. initiation, promotion and prograssion). These three stages of the oncogenic process have different biological characteristics. Studies to determine which chemicals effects which stages and to what degree are needed for risk assessment. The in-vivo biochemical system described in the report can be performed in a species specific and organ specific manner. In the report 1,4-dioxane is given to rats at doses of 168, 840, 2550, or 4200 mg/kg. DNA damage occurred at 2550 and 4200 mg/kg. This is the first description of genotoxicity of 1,4-dioxane in-vivo. Hepatic ornithine decarboxylase activity was also induced by 1,4-dioxane. This 1,4-dioxane appears to be a weak genotoxics carcinogen and a strong nongenotoxic carcinogen.