I dont DIY, but I thought about this for awhile.
What I decided was - because the dose makes the poison, the safest flavourings would be those that have many different chemicals in low concentrations, rather than a few or single chemicals in higher concentrations (Excepting things with high toxicity of course)....
So basically what I am doing is picking flavours with multiple ingredients, and mixing a bunch of compatible flavours together. Another option would be to regularly change your flavour.
Just a rough way of hedging your bets, avoiding single compound flavourings, and getting a variety.
Organic flavours tend to have more chemicals, but they also tend to be bioactive. Synthetic tends to rely on single compounds, or a small number of compounds, also sometimes bioactive. Hard to guess even what all the metabolites are, or if they are truely safe.
Even in food, nobody eats 1000 banana flavoured lollies a day. And if they did, who knows what would happen.
I mean generally speaking, GRAS is a guess. MSDS is usually over cautious, and also often somewhat guessy. Toxicology studies where they are done are very useful, indeed, and metabolites, but also its dose dependant.
PG has a very low level of a one tiny amount of a toxic metabolite, but no exposure study has ever revealed anything but irritation, or sensitivites/allergies (possibly because of this one very low level of one toxic metabolite). It can be harsh on the throat with the nic too.
Conversely VG is viscous, and seems to sit in the lungs heavily for many. But its also a natural body compound and can even be metabolised directly in the lungs. Which is why for people with various sensitivies, they have to balance the two ends, and find their own mix that works.
Same goes with flavours. Part of it is how you feel when you vape them. A n=1 subjective experiment.
Part of it is coming up with a mix, where your not taking in too much of one compound....
I mean, one would easily guess that these "gras" chemicals arent as bad as tobacco, but people havent consumed them in vast huge quantity before. Nor have they been well studied. Still think its most likely to be much safer than tobacco, but why be blaize about it?
Safest way to hedge the bet is instead of eating 1000 banana sweets a day, eat 10 bananas, 10 blackberry, 10 toffee. See what I mean?
Thats just how I am currently thinking about it, ATM basically mixing about four compatible flavours into my vape, each with a variety of components, and no stand out single chemicals. And after awhile ill change them around a bit. Hedging my bets.
For DIY, that would make life complicated, cause youd be adding a tiny bit of a load of different stuff, but you could really really ensure theres not much of any one compound, with certainty and that all the compounds are _relatively_ trustworthy based on rough guesswork.
There once was a day, when u didnt know if the berry on the vine would kill you, or be tasty food. People just got hungry and gamed it, by eating the tiniest amount and seeing what happened.
If lots of people ate it, after being cautious, and didnt die, or get sick, it became food. Ultimately we still live in that same world, full of unknowns and daily risks, but we rely on authorities to tell us that things are safe, when only seriously involved scientific study, that usually isnt done, or done correctly, can truely tell us that (and to understand the studies properly ud need a scientific background).
I think its best to assume with everything, including food, beverages etc, that we dont really know for sure, the full metabolic effects and metabolites etc.
Not to be _paranoid_ but have a _little_ reasonable caution, like our anscestors and the berry, rather than be like modern folks:
Gobbling down anything that gets some kind of guesstimate government tick, and frowning on anything that gets the same guesstimate cross mark.
We should remember the romans and lead piping, and the modern day addition of alzheimers causing aluminium to drinking water for no other purpose than to make it "sparkle". These authorities are often none too smart. They boo-hoo things that arent that dangerous, and okay things that can be dodgy as. Theres alot of unknowns still.
You just gotta be a bit like the caveman and the berry. Risk is part of life. Manage it using reasonable caution and thought.
