The scientific evidence linking both processed meat and tobacco to certain types of cancer is strong. In that sense, both are carcinogens. But smoking increases your relative risk of lung cancer by 2,500 percent; eating two slices of bacon a day increases your relative risk for colorectal cancer by 18 percent. Given the frequency of colorectal cancer, that means your risk of getting colorectal cancer over your life goes from about 5 percent to 6 percent and, well, YBMMV. (Your bacon mileage may vary.) “If this is the level of risk you’re running your life on, then you don’t really have much to worry about,” says Alfred Neugut, an oncologist and cancer epidemiologist at Columbia.