It's very well known what we are dealing with.
It may be well known when dealing with nicotine & PG... but we have little data on the flavorings. Some flavorings are molecules used in the ppm range, and likely have little to no effect- but we still don't know for sure. New flavorings are coming out often, there is a swing towards "organic" flavorings by vendors trying to separate themselves from the pack in this unregulated free market. Such as using "organic" vanilla extract, which involves steeping vanilla beans in ethanol. This produces a "tea" of hundreds to thousands of complex compounds that we have no clue what they're going to do when put in the reactive crucible of a hot atty with other unknown chems. Other vendors are making "organic" tobacco flavored ejuice by soaking tobacco and making tobacco "tea". Again, huge unknowns when put to that red-hot atomizer. I've seen a vendor using mushroom extracts. Mushrooms are mostly proteins & water. Our lungs are tricky & well-protected, and often the response to inhaled proteins unknown to the body, is that the immune system mounts a massive counter-attack in the form of an allergic response. It how our bodies protect against disease & (mostly in days gone by) parasites.
Now, these new potions/concoctions/etc, may end up being the best thing ever- or they could end up being every bit as bad as combusting tobacco, possibly worse. We don't know. So many variables are being introduced at such a fast pace, and most consumers see the word "organic" and related it to "healthy", which is a false association. It may be good when dealing with tomatoes that go through a very tough digestive system, but when it's applied to one of the most sensitive systems in the body, it's a totally new ballgame. And I think a lot of newbies get the wrong idea about ejuice Co's. I think a lot of people assume that their "american made juice" is being whipped up by PhD's in lab coats, slaving over hot beakers & cool distillation rigs, or working with reagent grade solvents, and rotovap's, all to produce the next 15mls of apple pie juice.
This is far from reality, and while I have no problem with it (they have tasty recipes!), some people might.
And the population that they're being introduced to are already compromised to some degree or another. There may be deaths out there that were a response to vaping, that no one knows was due to vaping, because the disease/defect causing the mortality ended up being chalked up to smoking due to the fact that the guy that croaked was a 20yr smoker.
Like a few others, I'm kinda playing devils advocate. Of course I'd like to see us unregulated, or at least successfully self-regulated. I am uncomfortable with the number of variables being introduced to the original model. Sometimes adding just two "organic" or "naturally derived" components to ejuice can raise the possible combination of variables exponentially. Than can be a problem when troubleshooting...
And/Or... people die every day from all kinds of stuff. Life is terminal- period.
With that in mind, I'm kinda torn about whether I should care about all this stuff (and other stuff).