That would be you, this time around, champ. A nebulizer does exactly the same thing as an ecigarette - convert a liquid to an aerosol for the purpose of inhalation. Also, guess what compound is used in nebulizers when the desired medication is not water soluble? Yep, propylene glycol. The exact same one used in e-cigarettes.
Except the fucking delivery method is distinct, because of ignition. Medical nebulizers use ultrasonic waves. What's the confusing part, exactly? Not the same. Completely different. We've established the materials alone aren't dangerous, that the delivery system may be. Review the existing literature about it, it takes about 20 second. The consensus is "using ignition to vaporize is almost definitely a bad idea." Hence nicotine *inhalers* (Nicotrol) being FDA approved for delivery. Because of the lack of ignition. Because that novel part of e-cigarettes has had no review, no clinical study, etc.
UNDERSTAND YET? HEATING THINGS TO VAPORIZE THEM GENERALLY MAKES THEM MORE REACTIVE, THIS MAY OR MAY NOT HAVE SIGNIFICANT HEALTH IMPACTS.
Get it, fuckstick? Delivery system. Completely novel. Not sure how many times I have to post it.
I'm surprised you didn't notice that point when you reviewed the existing literature.
Haha, just kidding, you just decided you were an expert based on....right, right.