The chemical name is polytetrafluoroethylene, and the commercial name is Teflon. The substance is widely used in the inner pot of rice cookers. Studies have shown that the substance will become a toxic substance under the action of high temperature exceeding 260 degrees. 
Teflon materials are also used in medical, metallurgical and other fields
 some people think that the rice cooker will make  Poisonous rice.