Generally, fresh vegetables properly cooked do not cause cancer, but improper storage or cooking methods cannot be ruled out to produce carcinogens. Vegetables are one of the food groups that we must consume every day, which can provide dietary fiber, vitamins, and minerals to the body, and the recommended daily intake for adults is 300 to 500 grams. However, if vegetables are stored and cooked in the wrong way, they may produce carcinogens. 1. Storage: Moldy vegetables may produce aflatoxins. Aflatoxin often occurs on the surface of moldy materials such as corn, nuts, peanuts and melon seeds. The amount on the surface of moldy vegetables is relatively small, but this possibility cannot be ruled out. Aflatoxin is an important risk factor for liver cancer. At the same time, rotting and spoiled vegetables are easy to release nitrite, which is also one of the carcinogens, easy to trigger esophageal cancer, stomach cancer. 2. Cooking method: Vegetables may produce carcinogenic substances during cooking. Vegetables with high protein content will produce benzo(a)pyrene when cooking at high temperature, which is a class 1 carcinogen. It is most commonly found in roasted meat. Vegetables are roasted at much lower levels than roasted meats. Starch-rich vegetables may produce the carcinogen acrylamide when roasted at high temperatures, such as roasted potatoes and roasted sweet potatoes. In addition, it should be noted that vegetables may be sprayed with pesticides during the growing process, and should be washed before consumption to avoid pesticide residues that may be harmful to health. To summarize, vegetables should be consumed when they are fresh and cooked at low temperatures.