It is proposed to investigate the role that nitrite and N-nitroso compounds may play in the etiology of human cancer. The focus of the program is on determining the endogenous synthesis and flux of precursors of nitrite and nitrosatable N-compounds in the gastrointestinal tract of man, and the influence of diet on formation, stability and reactivity of nitrite. A major goal is to develop an analytical approach to evaluation of the specific risk for an individual from endogenous nitrosation reactions. A second major goal is to develop information which will lead to dietary prevention of endogenous nitrosation. These studies will be conducted in man and experimental animals, and will integrate the skills of a wide variety of scientific disciplines.