Propylene Glycol Toxicity: Safe to Vape or Not? Propylene Glycol Vape for DIY E Liquid From Just 3.49 All E Cigarettes Emit Harmful Chemicals, but Some Emit More Than Others Berkeley Lab Berkeley Lab News Center E Cigarettes 101 UMBC MIECHV What's in your vape? Don't be fooled by the flavorsinside are harmful chemicals like propylene glycol, benzoic acid, nicotine, and glycerol that can damage your lungs, irritate your body, and keep you What's in an e liquid or vape juice? The main ingredients are propylene glycol (PG) and vegetable glycerine (VG). These are solvents that are basically used to dissolve and carry the other ingredients.