Many different chemical substances cause cancer. Dozens of chemicals in tobacco smoke, including nicotine, have been shown to cause cancer ( Figure below ). In fact, tobacco smoke is one of the main sources of chemical carcinogens. Smoking tobacco increases the risk of cancer of the lung, mouth, throat, and bladder. Using smokeless tobacco can also cause cancer. Other chemicals that cause cancer include asbestos, formaldehyde, benzene, cadmium, and nickel.
Three friends Mark, John and Sam have very different views on smoking. Mark has never smoked and doesn't see what people see in it. John and Same both smoke about the same each day but John likes traditional cigarettes. Sam on the other hand chooses to use smokeless tobacco products.
Who is at higher risk for throat cancer?