As a guy who makes his own juice, it’s nicotine derived usually from tobacco or sweet potatoes suspended in a solution of either USDA food grade vegetable glycerine or propylene glycol, which is then mixed in the appropriate desired concentration with USDA candy/food artificial flavorings and more USDA food grade VG/PG.
You mention USDA food grade a lot. I will wager that’s not the case for a lot of grey market vapes. It will be at most, “best effort” food grade with the occasional “whoopsie not sure what was in that drum before we used it” thrown in to keep you on your toes.
Maybe buy juice from a reputable company then, or make your own like I do. You technically don’t know what pesticides were sprayed on your fruits and veggies either unless you grow em yourself, you don’t know if the cook at the restaurant you ordered at put arsenic in your soup, live a little.
