[Okie Sawbones]

This is what DuPont says:

At high temperatures, the quality of the coating may begin to deteriorate — it may discolor or lose its nonstick quality. This can begin to occur at temperatures above 500°F (260°C). If heated to an extremely high temperature, the coating may begin to decompose and give off fumes. Fats, butter, or cooking oil will begin to scorch and smoke at about 400°F (204°C). DuPont nonstick coatings will not begin to significantly decompose until temperatures exceed about 660°F (349°C) — well above the smoke point for cooking oil, fats or butter. It is therefore unlikely that decomposition temperatures for nonstick cookware would be reached while cooking without burning food to an inedible state.