Sorry, I read a paper on this 10 years back... The principle, as I recall, is that when a nanoparticle or nanofiber lodges somewhere, poking a membrane or anyw

Sorry, I read a paper on this 10 years back... The principle, as I recall, is that when a nanoparticle or nanofiber lodges somewhere, poking a membrane or anyway intruding, immune system cells attack it with increasingly caustic chemicals, trying to break it down. If it is too stable, they fail, but don't give up. It is this inflammatory response that underlies asbestos's toxicity. A smooth, locally flat surface does not, by itself, provoke that immune response, and chemically PTFE doesn't draw attention. But PTFE happily adopts any shape. So, maybe nobody makes PTFE microfibers or nanoparticles on purpose, but that doesn't mean there aren't any. The short story is that tests showing PTFE surgical implants don't evoke an inflammatory response do not tell you much about effects of PTFE in different circumstances. Likewise: people can wear metal jewelry for years, but that doesn't mean you can poke a knife through somebody with no effect. There was a recent report that those mesh tetrahedral tea bags each release literally billions of plastic nanoparticles into your tea. That cannot have been deliberate. I wonder if those have been banned or recalled yet...