[themulticaster]

As far as I know, non stick surfaces are mostly (always?) made out of PTFE (brand name Teflon), which is a little unusual in that it starts releasing toxic gases when it's heated way before it shows any signs of structural damage or deformation. This gets dangerous to humans from about 240C, but even at 220C PTFE will release trace amounts that can be toxic to birds.

With this in mind, I'm baffled about how many products with non-stick surfaces are marketed as safe up to 240C, considering that household ovens are often bad at controlling temperatures and can swing 20-30C above and below the set temperature.