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"Did any birds die?" is an approach to this problem that I would expect from an undeveloped nation a hundred years ago. It is both excruciatingly short-term in focus and so imprecise that the results are useless for anyone who is not himself a rat or a canary.I sort of agree, but birds do make a convenient study subject because they are exquisitely sensitive, much more so than humans.
The lowest temperature at which PTFE coatings have been seen to evolve breakdown products (that I know of) is 240 deg C. Even then, the only detected product was micro-size PTFE sublimate, which can lead to what we call "fume fever", but reports of this actually happening are rare, even in factory workers who are exposed at much higher levels.
The temperatures at which PTFE pyrolysis really starts to give off nasty shit are way higher [1], but even then, evidence of physiological harm is sketchy. Anecdotally, I know a few people, including my father, who have left a nonstick pan on the stove, got distracted, and burned the coating right the fuck off. Aside from the smell, no ill effects were observed. This isn't scientific at all, but if burning PTFE is that toxic, one might have expected some effects.
> It does not answer the question, "What are the long-term effects on humans of short excursions outside of normal cooking temperatures?"
This is true, but undertaking such a study would be both impossible and pointless, because we are exposed to millions or billions of times more fluorinated compounds from clothing, furniture, and carepeting, than we could evey hope to get from nonstick cookware, even if you overheat it regularly.
Keep in mind that billions of pieces of nonstick cookware have been in use every day around the world for the past seventy years. And all time, factory workers have been exposed to the manufacturing process. That's plenty of time for problems to have been observed on some level, but they just haven't. The problems we're seeing come from the billion-fold higher levels of PFC we get from other sources.
To repeat an analogy from an earlier comment, worrying about nonstick cookware is sort of like a lifeguard who works in the sun all day, but obsessively blacks out the windows in his home because he's worried about UV radiation getting in his house. It makes no sense.
1 - https://sci-hub.st/10.1289/ehp.7511197 - Waritz, R. S. (1975). An industrial approach to evaluation of pyrolysis and combustion hazards. Environmental Health Perspectives