Studies show that in about 5 minutes, a Teflon-coated pan heats up to around 750ºF. According to the Environmental Working Group, thermal degradation of PTFE leads to a litany of toxic compounds, including highly corrosive and lethal gases, and PFIB, a chemical warfare agent that is 10 times more lethal than phosgene (a chemical warfare agent used in WWI and WWII). These compounds persist in the environment and are not known to break down further.