Self-squeezed peanut oil is classified as a first-class carcinogen because of poor material selection. The main raw material of peanut oil is peanut. If the selected peanuts are not fresh or even moldy, aflatoxin will appear in the squeezed peanut oil, which is recognized as a highly carcinogenic substance. Such self-squeezed peanut oil naturally belongs to the first-class carcinogen.

As far as raw materials are concerned, peanuts are particularly prone to produce aflatoxin, and aflatoxin B 1 is recognized as one of the strongest carcinogens in the world. Whether peanuts used for oil extraction are infected with aflatoxin cannot be identified by naked eyes and must be tested. However, self-pressing usually does not have such technical conditions, so aflatoxin is easy to exceed the standard, which has become a serious food safety hazard of self-pressing peanut oil. On the contrary, large industrialized oil production enterprises have strict quality control systems, and aflatoxin is a mandatory item, so the finished peanut oil produced by large oil production enterprises is safer in this respect.

Peanuts that are not well preserved are prone to mildew and breed aflatoxin. Because peanuts are easy to regain moisture even if they are dried in the sun, peanuts after regaining moisture are easy to get moldy and breed aflatoxin. In rural areas, dried peanuts are generally stored in sealed bags and cans because of their small quantity, which is a common sense known to every peanut farmer. There are so many peanuts on the market, which are generally piled in warehouses, and it is easier to mold and breed aflatoxin.

Whether it is squeezing or leaching, according to the production technology of edible oil, the initial "crude oil" must be refined through decoloration, deodorization and other steps, and the content of aflatoxin after refining is very low, which can be basically ignored. Self-squeezed oil is often crude oil obtained by workshop squeezing without further treatment. Some researchers have found that "crude oil" is also squeezed from severely moldy peanuts.

Aflatoxin (b 1-the most carcinogenic) exceeds 800ppb, 20ppb, and 1ppb is equivalent to 1 mg in1ton of grain). This is because some peanut residue is brought in during the pressing process, and the toxin content in the residue is very high. However, after refining, the content of aflatoxin in "crude oil" produced by the same raw materials is lower than 1ppb, which is basically negligible.