Here's some technical information from a 1998 issue of The ASA Newsletter (Applied Science and Analysis, Inc.):
Perfluoroisobutene (PFIB, 1,1,1,3,3-penta fluoro-2-trifluoro methylpropene, CAS No. 3812-21-8) is a fluoro-olefin produced by thermal decomposition of polytetrafluoroethylene (PTFE), e.g., Teflon [emphasis added]. Overheating of PTFE generates fumes of highly toxic PFIB and poses a serious health hazard to the human respiratory tract. PFIB is approximately ten times as toxic as phosgene [a nerve gas]. (Source)Teflon offgasses at 446°F; a Teflon pan on an electric burner can reach over 700°F in three to five minutes. So, it appears that a Teflon pan on a typical electric stove can offgass highly toxic PFIB, which is about 10 times more toxic than a nerve gas. Here's an infographic on cooking temperatures and effects from the Environmental Working Group:
Once again, I expose my ignorance by sharing the fact that I thought this chemical had been banned. Not true. The EPA has asked Dupont to "phase out" Teflon; Dupont has said they'll reduce the amount produced by the year 2015. So, it's not banned - and the EPA asking nicely to phase it out probably won't make a difference. Besides, with 95% of us having it in our bodies already, it might be too little too late.
My recommendation: avoid all use of pans with Teflon-like coatings. Accept the fact that food can and will stick to pans but use natural oils and butters to help prevent this problem. Much better than inhaling Teflon fumes or having it in your blood.