The three major carcinogens recognized in the world are aflatoxin, benzopyrene and nitrosamines.

1. Aflatoxin is a strong carcinogen that mainly contaminates grain, oil and grain and oil products, especially moldy grain, such as peanuts, corn, etc., which can induce liver cancer.

2. Benzopyrene is a polycyclic aromatic hydrocarbon that contains more than 20 known carcinogens. It is commonly found in smoking smoke, high-temperature vegetable oils, burnt food, and over-fried food. A source of high activity and mutation.

3. Nitrosamines are strong carcinogens produced by the combination of nitrosamine salts and proteins in an acidic environment. Nitrosamines are contained in food, cosmetics, beer, and cigarettes, especially in smoked bacon. The content in food is relatively high.