Answer: nicotine
Explanation:
Makers of e-cigarettes and other ENDS often claim the ingredients are safe. But the aerosols (mixtures of very small particles) that these products produce can contain addictive nicotine, flavorings, and a variety of other chemicals, some known to be toxic or to cause cancer. The levels of many of these substances appear to be lower than in traditional cigarettes, but the amounts of nicotine and other substances in these products can vary widely because they are not standardized. The long-term health effects of these devices aren't yet known.
