The Not So Hidden Dangers of Electronic Smoking Devices No tobacco product is harmless according to CDC scientific evidence. E cigarette aerosol that users breathe from the device and exhale can contain harmful substances including heavy metals like lead, volatile organic compounds, Propylene Glycol (PG) Antibacterial Activity Infographic Flickr Glycol and Glycerine in E Liquid Manufacturing [All You Need To Know] Vaping propylene glycol and vegetable glycerine may lead to lung inflammation