What amount of chewing tobacco causes mouth cancer?

Why run the risk? I agree that the risk of cancer from chewing tobacco exists. What amount s difficult to answer. As a rule of thumb, it takes time and frequency. Genes would probably make you more susceptible. There are other risks too. Staining of teeth....Smell, waste of money.. A bad habit . Walk on the beach, smell the roses, play sport, visit a friend, it is just a ad habit do not play with fire.