Yes there are studies. I'm not necessarily worried about vg/pg or nicotine.........it's the flavoring & coloring that has me bothered & it has for a long while. Perfumers (Flavors) Apprentice has paid to get numerous studies done regarding their flavorings.
What you need to realize is that just because a flavor is "food grade".......it doesn't necessarily mean that it's vape/respiratory grade. Digestion is an entirely different process than inhaling something directly into the lungs. PG is used as a carrier in many inhaled medications here in the USA (albuterol, atrovent, racemic epinephrine, etc)
I'll never forget the first bottle of watermelon juice I got in the mail. Sure, it tasted sweet.........but um, that hot pink color is not naturally existent in nature, so I probably shouldn't inhale whatever chemical is used to create hot pink (as much as I love pink)
7.35-7.45 is a neutral PH...........anything less than 7.35 is technically acidic, so if any of the juices you vape are a lower PH than that, they are technically an acid. hmmmmmmm.........I could probably find some of that little paper on a roll at work & test out some of my juice. I forget the name, I'm thinking it's litmus paper.
