Medical stone coating is PTFE, which is Teflon. Teflon coating is non-toxic, even if it falls off during use, it can't be absorbed when eaten in the stomach, so it is non-toxic. The toxicity of PTFE coating is that it decomposes into harmful substances easily absorbed by human body at high temperature. Therefore, the use of non-stick pot D should avoid long-term empty burning. On the other hand, cooking food with high oil temperature will produce a lot of carcinogens, which must be paid enough attention to. To sum up, the medical stone pot has nothing to do with medical stone, and its essence is Teflon coating. Normal use of non-stick pan will not pose a threat to health, and normal frying can not make the temperature of pan exceed 260 degrees, so it is necessary to avoid long-term dry burning.