Like so many discoveries, Teflon was the result of a mistake. On April 6, 1938 a Dupont scientist, Roy Plunkett, was doing experiments with tetrafluoroethylene gas when he discovered that some had polymerized. The stuff was solid and slippery, and polytetrafluoroethylene (PTFE) was patented by Dupont in 1941 In the sixties Dupont started selling it under the trade name Teflon for cookware.
A few years back there was serious concern about the possible off-gassing of perfluorooctanoic acid (PFOA) during the use of non-stick pans. It is a possible carcinogen; According to the American Cancer Society, "Studies in lab animals have found exposure to PFOA increases the risk of certain tumors of the liver, testicles, mammary glands, and pancreas in these animals."
However pans were never a major source of it, most being burned off during manufacture. Poor TreeHugger Emeritus John Laumer took a huge amount of abuse for trying to take a dispassionate look at the subject and lost us a pile of readers ("This article convinces that you are industry shills" and "This post makes me want to stop reading treehugger.com forever"), and in fact according to Dupont, they haven't used PFOA since 2012.
People are still blaming Teflon pans for killing birds, but the cookware manufacturers say that it can be any kind of cooking that does it.
Cooking fumes from any type of unattended or overheated cookware, not just nonstick, can damage a bird's lungs with alarming speed. This is why bird owners should take steps to protect their pets, such as keeping their birds out of the kitchen, never leaving cookware unattended, never allowing pots and pans to overheat, and making sure that their kitchen is properly ventilated at all times.
But others claim still that "Birds are susceptible to a respiratory condition called "teflon toxicity" or "PTFE poisoning/toxicosis." And like the canary in the coal mine, I suspect that canary in the kitchen is telling us something we should pay attention to: air quality matters, whether it is teflon or any other toxicity. (That's why I am no longer a fan of gas ranges)
Besides, there are lots of good alternatives to PTFE coated cookware that don't have any kind of plastic coating. So why bother?