It is my understanding that breathing the vapour given off by just about any glowing metal is inadvisable at best, although that is normally something which is only of concern to welders who may be exposed to much higher concentrations from far higher temperatures and over much longer periods than we are ever likely to be concerned with. SS at the levels and frequencies we are likely to be exposed to is relatively safe, as much as anything can be - 316L in particular, is supposed to be safe (in many places mandated) in commercial kitchens, where a pot boiling dry can get glowing pretty easily, and I've not seen any panic stories about that. I wish I'd kept links to some of what I've read about relative risks in the various wire types we use - some were written or presented by proper experts in industrial safety and related fields, so I'm pretty much taking their word for it! The consensus seems to be that SS316L is as safe as anything is likely to be.
Nickel is apparently outright nasty, and Ti isn't too great either. I'm not sure what is given off by Kanthal, but I make a practice of not pulsing beyond what I need to do to make sure any hot-spots are eliminated with anything. I dry burn to clean, but avoid anything given off by the coil at any kind of serious temperature - that is, after all, the stuff you are trying to clean off, so isn't very nice by it's very nature! I heat to glowing and quench under running water, and the coils come out nice and shiny (even though the shape of mine is pretty messy).
I use it in temperature controlled (where supported) and power modes, and on a basic device (Kanger Dripbox v1) with no control except a firing button and basic protection circuits. No mech mods though, which may give some idea of my personal level of risk aversion!
I've had SS316L giving a nice even glow on contact coils, so the oxides do seem to provide an insulating layer. I'm not a medical expert, biologist, chemist, metallurgist or any kind of expert - just regurgitating what I've read, and as always, this advice is worth precisely what you paid for it
There is some level of risk in almost everything, and all we can do is our best to ameliorate it, by ensuring decent ventilation, for example, and working at arms length where possible. Most of all, it's your decision - if you don't feel comfortable doing it, then don't!
If anyone out there is able to provide any real data on relative safety of heating coil wires, please do - I'm always looking to learn more.
