• Most contain nicotine, even some that claim to be free from this highly addictive substance. Nicotine can impair brain development in adolescents and can lead to addiction to other drugs.
• Some brands include formaldehyde, a naturally occurring chemical, which, in large amounts, can cause cancer. In fact, a study published in the New England Journal of Medicine showed that in some types of e-cigs, the amount of formaldehyde released was higher than regular cigarettes.
• They're offered in a variety of fun flavors, making them appealing to youth. Some of these flavors are made with a chemical called diacetyl, which tastes like butter but can cause bronchiolitis obliterans, a type of lung disease offered referred to as "popcorn lung."