You mean rocket fuel isn't good for you? Pry healthier than Redbull or any energy drink, lol.
Lol, well... the FDA has labeled those chemicals safe for ingestion... Your digestive system can handle small amounts of those chemicals... Your lungs, on the other hand, don't have any type of digestive properties. What you inhale goes directly to your blood stream. Anything that can't be absorbed sticks in your lungs.
It doesn't matter where the juice comes from, the ingredients are pretty much rock solid across the board. The levels of each ingredient will vary from vendor to vendor, but e-juice is still mostly comprised of otherwise toxic chemicals.