From what I found, burned glycerine creates Acrolein, which some claim causes cancer, but that is contested:
Considering the tiny amount of emissions from burnt propylene glycol (which I'm not even sure behaves EXACTLY the same way as ALL glycerines) that vapers MAY get, it's still probably 98% safer than smoking tobacco. As soon as people get that "burnt taste" they refill or change their atty.
Keep your atty wet and it shouldn't even be an issue.
Kristin --Intelicig did a full study of this and it was shown that atomizers using VG do not produce Acrolein at all.
Sun