Aflatoxin in fungi is a carcinogen, and the toxin can induce liver cancer in humans, monkeys, rats and poultry, and the minimum time required for carcinogenesis is 24 weeks. Prevention of fungal contamination of food, should pay attention to: 1, the home collection of peanuts, corn, dried white potatoes, rice, millet, etc. must be sun-dried and sun-dried, stored in a dry and ventilated environment. 2, moldy peanuts, dried potatoes, dried radish, etc. should be removed and discarded, livestock and poultry can not be eaten. 3, peanut oil and cottonseed oil should not be stored for a long time; when suspected of large quantities of cereals and oils, dairy foods have fungal contamination, should be asked to check the epidemic prevention station, allowed to issue, sale or consumption. The stale oils all contain a chemical composition, which can make the structure of the protein mutation, resulting in mutated protein cells lose normal function and to the early stage of cancer cell transformation. In addition, there are chemicals that replicate acids to accelerate the aging process. Therefore, animal and vegetable oils should not be stored for too long, and oils that have deteriorated to produce a harry odor should not be consumed. The food fried and stir-fried with haram-flavored oil not only tastes bad, but more importantly, it can lead to cancer and shorten the life span.