[slumdev]

The idea that PTFE doesn't break down except at very high temperatures is not true.

Breakdown begins to occur at either 200 or 260 degrees Celsius (depending on what data you're looking at). These temperatures are well within the realm of temperatures that even a home chef might encounter.

[nate_meurer]

> Breakdown begins to occur at either 200 or 260 degrees Celsius (depending on what data you're looking at).

This isn't good data. The stories of PTFE coatings breaking down at less than 260 deg C are anecdotal. The most well known one comes from someone who swears their chickens were killed by coated light bulbs in a coop.

The lowest temperature that has lead to bird deaths in a controlled laboratory setting is 280 deg C, which is about 580 deg F. [1] This is way freaking hot, and likely only to be reached by accident.

Even in the case of accidental overheating of non-stick cookware, there have been only a few verifiable cases of injury, and certainly no fatalities. Most cases of polymer fume fever have been gleened from among workers in factories, which is remarkable considering that billions of pieces of nonstick cookware have been in use every day around the world for the past seventy years.

Also note that cooking fumes from food are themselves toxic, and kill birds and lead to long term respiratory issues in humans much more easily than PTFE coatings.

1 - https://sci-hub.st/10.1289/ehp.7511197 - An Industrial Approach to Evaluation of Pyrolysis and Combustion Hazards

[slumdev]

> The lowest temperature that has lead to bird deaths in a controlled laboratory setting is 280 deg C

"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.

Your data answers the question, "To what temperature must we heat PTFE in order to kill small animals?"

It does not answer the question, "What are the long-term effects on humans of short excursions outside of normal cooking temperatures?"

[nate_meurer]

> "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

[slumdev]

The last time I needed an x-ray for a broken bone, I asked the x-ray tech for a lead vest to protect my torso and groin area.

He told me that it was pointless because I would be exposed to more background radiation throughout the course of my normal life. He did not understand that ionizing radiation damage is cumulative and that there is no safe limit for exposure. Annoyed with my request, he gave me the vest anyway.

Is there a safe limit for exposure to PFAs? I would readily concede that the risk to an individual is probably negligible, but like in the case of x-rays, population-level risks probably do exist for even the smallest exposure.

That said, I would also support eliminating all sources of PFAs, just like we tried to do with CFCs and asbestos.

[nate_meurer]

You were right to ask for a shield. I would do the same thing, and I'd be a little pissed that I had to ask.

However there's a big difference, in that the x-ray you got actually delivers a substantial amount of ionizing radiation-- up to one full percent of the average annual background dose. There is no evidence that even a lot of normal x-ray scans have any effect on health, but at least it's a physical possibility.

In contrast, the level of chemical hazard from nonstick cookware is a billionth or trillionth (or even smaller) than what's in the carpets we all grew up playing on, or the clothes we wear and furniture we sit on every day.

To use another analogy, worrying about nonstick cookware is like worrying about the ionizing radiation coming from a banana that's sitting uneaten across the room from you.

I agree about absestos, and I fee the same about lead as well. Those are nasty poisons that, contrary to popular lore, cannot be used and applied safely such that they won't eventually get loose and become a health hazard. I've been thinking about asbestos this week because I've been replacing ceiling light fixtures in my house, and it's impossible to do without causing the asbstos-filled popcorn texture to rain down like snow. It's fucking unbelievable what previous generations afflicted us with.

EDIT:

I feel compelled to repeat that common cooking fumes and smoke are known toxins and carcinogens. It makes no sense to be more concerned about tiny amounts of aerosolized PTFE than the far greater amounts of cooking smoke and fumes that will inevitably be emitted by your food at the same temperatures.