Preserved fish will produce harmful substances during curing and smoking. When smoking at high temperature, incomplete combustion of wood will produce harmful substances, and high-temperature barbecue of pork will also produce carcinogens such as benzopyrene. Benzopyrene is a strong carcinogen, which is mainly produced by incomplete combustion of organic matter at high temperature. It can be said that there is smoke in most places. Animal experiments have proved that long-term inhalation or consumption of food with high benzopyrene content is easy to induce lung cancer, liver cancer, gastrointestinal cancer and so on.