The monomer is tetrafluoroethylene, which is a gas: https://en.m.wikipedia.org/wiki/Tetrafluoroethylene https://en.m.wikipedia.org/wiki/Tetrafluoroethylene As

The monomer is tetrafluoroethylene, which is a gas: https://en.m.wikipedia.org/wiki/Tetrafluoroethylene https://en.m.wikipedia.org/wiki/Tetrafluoroethylene As I understand it, the three concerns are: 1. The manufacturing and processing of PTFE is usually done in water with a fluorosurfactant mixed in. The fluorosurfactant varies from nasty to extremely nasty. 2. PTFE could potentially degrade into something less benign than PTFE. 3. PTFE has mediocre thermal stability — it starts to decompose a bit at temperatures that you can easily reach with careless cooking and, notably, it starts to decompose while it’s still a solid. This makes any kind of theromoplastic processing (extruding, molding, etc) a bit nasty. I think the decomposition products are gasses. They are noted for killing birds and concentrations at which their presence is not obvious to mammals.