Nearly all nonstick products contain long-chain perfluorinated chemicals, or PFCs for short. PFCs are man-made, synthetic chemicals used in thousands of industrial applications.
Polytetrafluoroetheylene (PTFE, or Teflon) is a type of PFC. If you've ever purchased a piece of nonstick cookware or bakeware, you've more than likely seen a warning label cautioning you not to use it at extremely high temperatures.
While PFCs are stable at most of the temperatures typically used for home cooking, the material can begin to degrade at temperatures above 500 degrees Fahrenheit or when physically damaged.
Dangers of Damaged Nonstick
It is not PTFE itself that is toxic to humans but rather the fumes emitted when PTFE is heated to high temperatures. Therefore, when a Teflon pan is scratched, there is no danger since flakes of solid PTFE are chemically inert.
But when a scratched nonstick pan is heated, it will emit toxic PTFE fumes much more quickly and at lower temperatures than will a nonstick pan that is structurally intact. When a nonstick surface is scratched, its potential to prevent stuck food is also diminished, so even from a practical rather than a health standpoint, using scratched or damage nonstick products should always be avoided.
Other Possible Hazards
As noted, PTFEs emit toxic fumes when heated to exceedingly high temperatures. Manufacturers claim that nonstick cookware is safe for use with the temperatures that home cooks typically use, but the Environmental Working Group (EWG) claims that their own testing revealed that a structurally intact nonstick pan emits toxic fumes after only two to five minutes on a conventional stovetop.
To reduce the harmful effects of PTFE exposure, never use a nonstick pan in a 500-degree Fahrenheit oven, and never allow a pan to get exceedingly hot on a stovetop.
PFCs and Human Health
PTFE fumes kill birds and other wildlife after minimal exposure, but the effects of PTFEs on human health are still little understood. One cause of concern by the Environmental Protection Agency (EPA) and other groups is that PTFEs are incredibly persistent, found in humans in all populations in which the EPA has conducted testing despite being synthetic chemicals.
Breathing in PTFE fumes is believed to cause flu-like symptoms in humans ("Teflon flu" or "polymer fume fever" as the affliction is commonly known).