My remarks were made in context where it is being claimed that “a new mystery ingredient” is cause for concern. I stated what ingredients are used as a point about how unlikely it would be for something out-of-the-blue to permeate the market.

Just a sidenote, a lot of nebulized drugs also contain propylene glycol. I know it's not quite the same delivery mechanism as vaping, but it does end up in the lungs.

In addition to the delivery method being slightly different (because heat) the dosage is much higher.

The few studies out there, mostly related to theatrical fog, state that it causes irritation to mucus membranes. Is that what doctors are seeing in vaper's lungs?