E-cigarettes can be dangerous because they can contain nicotine. Nicotine is a highly addictive chemical that can harm brain development, which continues until age 23-25.
According to the Centers for Disease Control and Prevention, studies found that even some e-cigarettes that claim to contain zero percent nicotine do still contain some nicotine. Studies have already confirmed that e-cigarettes are not safe for youth, young adults, pregnant women, or adults who do not already use tobacco products. The Food and Drug Administration has not approved any e-cigarette as a safe or effective method to help smokers quit; e-cigarette companies often market their products this way.