It's not possible to fry in a safe range. The safe range is <500F. I use pans at a greater temperature than that for frying. Additionally, when the pans wear the surface degrades and becomes your food. This probably always occurs, but more when the products wear.
Also the vaporization of teflon is probably not a step function but a curve, and they set the safety range at some threshold. So in all likelihood you are inhaling who knows what at even the safe ranges.
