Awkward one for me to answer questions without coming over as slating other peoples work so I'll give my opinion and as is the norm YMMV.
For a long time now anything I make has a Ti hot end and a 316SS condenser, not just a metal tube glued into a blank or a blank with a hole drilled thru it.
The majority of the stems I make are custom orders and if I'm not happy with a certain design I will pass on my concerns. As the designer and manufacturer I'm the person responsible for the safety of my customers.
As @danielj says certain wood species need to be considered too.
@cybrguy stabilised wood is something I've turned and I don't particularly like it.
It isn't the nicest things to turn and it smells, not as much as horn.
The smell lingers in the stem for some time unlike horn which just stinks when you work it.
Not saying I won't turn it, just prefer not to.
@almost there your best bet is to repeatedly wax the stems you have and it should mask the stabiliser smell.
Stab wood isn't wood after the process of soaking and baking and it's properties change. The strength changes and IMO for the worse. It seems to lose the characteristics of wood and has none of the predictability wood has, bits chip out and it splits in odd places.
Since I started this I've read a lot of info on wood safety and plenty of MSDS.
The MSDS for one of the stabilisers I read stated that it causes contact dermatitis, something I've suffered from due to a machine cleaner and I was in full protective gear.
The MSDS also stated that this resin was partially soluble in water. Now for pen turners this isn't a worry but we are talking about a totally different situation.
For this reason I will not make any piece with a stab MP, if the resin becomes soluble in water you can bet the same thing will happen with spit.
CD was horrible enough on my hands, arms and legs I hate to think what it would be like on delicate lip skin.
Acrylics and polyesters I use as my build design eliminates any hot vapor coming into contact with them.
This used to be my daily and I was the PhattGuineaPiggie for this design.
It's all acrylic with a Ti insert and SS condenser.
The acrylic smelt a little the first couple of times I used it but quickly subsided. The vapor at the MP was and is well below any worrying temps and not once did it impart a taste to the contents of the VC.
@thejackalsmark and @danielj the MJ world has always attracted some of the worst people in society and it will continue to do so legal or otherwise. They just come in different guises these days.
Some people are genuinely unaware about material safety, others just don't care and can see a bandwagon to jump on, a way to market themselves and make a bit of money.
I've had folk ask if I can reduce the shipping costs, ain't gonna happen.
Everything I send goes out with a 'legit' tracking number.
Most packages are tracked and signed, covers mine and the customers ass this way.
thejackalsmark I'm glad you mentioned unusual stem materials as it sent me off on a quick search for
something I've wanted to use for ages, thankfully it was successful and the order will be getting placed soon.
@Squiby the egg stems were for shits and giggles and very delicate. I used the same egg and eventually it got dropped. I need to find a decent way of strengthening them before I do any more.
Also did this one and have shells to do more.
Can't beat a VC for efficiency, four tiny pieces of different extracts in a rayon ball.
Edit.
Again with a full SS condenser.
So good to hear from you in such a detailed manner. You have been at this so long that most of us are all pretty much amatures in comparison. I have not seen any of your work in the flesh, (too poor for high end) but you have posted pics enough that I can see that you are doing some very unique things at the hot end, safety wise, and that your art and concern, continuing all the way down the stem.
Regarding the egg stem and strength...if you havent already, check out forums etc. on goose and emu egg carving. You may find some ideas there.