Current evidence identifies health risks of e cigarette use; long term research needed American Heart Association Vaping has become common, but it's important to know what you're inhaling. Many e cigarettes contain nicotine, heavy metals like nickel and lead, and chemicals that can harm your lungs and overall health. U.S. e cigarette use stalls as health concerns grow: Reuters Ipsos poll Reuters The flavoring chemicals in e cigarettes are linked to a disease known as popcorn lung