The U.S. Centers for Disease Control and Prevention have recently become concerned about e-cigarette use yet scarcely mention that cigarette uptake has plummeted.
Cigarettes are the killer, not nicotine, but nicotine is what historically turned smoking into what the American Council on Science and Health (ACSH) deems a pediatric disease. Like caffeine, nicotine is addictive. If you smoked caffeine in a cigarette, it would be incredibly toxic whereas nicotine itself is relatively harmless. And because the CDC has overreacted to e-cigarettes, they become a cool rebellious thing for teems, just like cigarettes once were.