Teflon coated or imbedded nylon (Delrin, name brand) tenons were pioneered by Andreas Bauer in Austria I believe in the 1960’s and are primarily used in meerschaum pipes, although infrequently in higher end ones. 

Tenons are not subjected to anywhere near the heat that these materials can handle with ease and the materials are highly resistant to dimensional changes and they don’t stick to other materials or itself. 

They are great materials because they are virtually inert, which makes both of them, but especially Teflon incredibly safe to use in a variety of situations. 

I don’t have any studies to cite, but I believe it falls into the realm of basic common sense that you would be exposed to as much effects from Teflon, if any at all, from frying a single egg in a Teflon coated frying pan (nearly everyone owns or uses them and have for quite a long time now) as you would from smoking a pipe with a Teflon coated tenon for a hundred years. 

If you and billions of people haven’t died from cooking in and or eating food cooked in Teflon most or all of your life, I can’t see any reason to have this as a concern. 

Hmm... TEFLON? on a pipe tennon? I've never seen or heard of such a thing. Amusing that an artisan pipe maker tried it in the 1960s. Creative creatures, pipe makers. 🤓 I bet there's a reason it never caught on. Cheaper, better solutions already existed, (i.e. - shaping and fitting vulcanite and acrylic into briar). Now, threaded metal inserts for meerschaum? That's a different story. It might come in handy there.

As far as health risk, I totally agree with @Ted. It seems negligible to me. The actual chemical compound is a polytetrafluoroethylene (PTFE). In addition to non-stick frying pans, we also make high-end water bottles out of PTFEs. There is mixed info out in the wild about PTFEs, and not all of it is good. But, in researching this answer, I just learned (from ChatGPT) that TEFLON is even used in medical applications for implants and prosthetics. Surgeons are putting this stuff inside people's bodies on purpose to fix them! Sounds relatively safe to me.

I was watching a video from Mastro de Paja in Italian, but my italian is not perfect so I have to repeat that part couple of times and I understood they uses Teflon for the tenons, (i guess temperature and won't stuck in the shank).  When I checked a couple of Savinellis I have  with me now ( 315ks and 173) the tenons definitely looks like teflon material. I never paid attention to that.

Other pipes (vulcanite and acrylic) have what it looks like regular plastic.  I am talking mainly about filtered mouth pieces.

Thanks for your comments, I just recently get rid of all teflon pans at home, but it looks I cannot escape.