Vape juice contains a long list of chemicals, many of which aren't even listed on the packaging. Testing has also shown that vapes labelled "nicotine free" can have high nicotine levels. Vaping, Diacetyl, and Popcorn Lung: Is the Threat Real? Vaping360 Comparison of the stabilities of acetoin, acetyl propionyl and diacetyl Download Scientific Diagram Vaping lung illness: Harmful chemicals found in e cig flavoring juice