8 Vape Juice Ingredients to Avoid Toxic e Liquid Flavors What is Vape Juice? E Cigarette Direct 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. Vaping the sweetener sucralose may produce toxic chemicals Vaping lung illness: Harmful chemicals found in e cig flavoring juice Vaping releases toxic chemicals, including heavy metals, as well as ultrafine particles that go deep into the lungs. These increase the risk of heart and lung disorders.