Nicotine, propylene glycol, sweet flavorings, and various toxic chemicals like carcinogens and heavy metals are found in vape juice, posing health risks, especially to youth. What does PG and VG stand for? (a quick view in the chemistry of the E Apollo Vapes UK What is Propylene Glycol (PG) in Vape? Most vapes contain toxic chemicals that are bad for your health. Some are added to make the vapes taste or smell nice, and others are created when the battery heats the liquid.