Anti-smoking advocates and public health officials say advertising for conventional tobacco products such as cigarettes triggers increased experimentation among young people, leading to more smokers.
They worry the same scenario is playing out with e-cigarettes, which currently don't face the advertising restrictions that apply to traditional cigarettes.
That's bad news, they say, because of evidence that nicotine use can negatively affect the developing brains of teenagers, because so much remains unknown about the long-term effects of e-cigarettes and because of the potential that young people who try them could wind up as regular smokers.
E-cigarette sales in the US hit an estimated US$2.5 billion ($3.76 billion) last year. Researchers say e-cigarette advertising has grown along with the market, from an estimated US$6.4 million in 2011 to an estimated US$115 million in 2014.
While manufacturers insist their products are aimed solely at adults - in many cases, smokers looking for a way to satisfy their nicotine cravings while avoiding the well-documented harm of tobacco - the devices have become increasingly popular among young people.
CDC reported last year that the number of middle and high school students using e-cigarettes tripled from 2013 to 2014, eclipsing their use of traditional cigarettes.
Matthew Myers, president of the Campaign for Tobacco-Free Kids, said companies "are getting to them [kids] early, long before they become teenagers". "It was the case with cigarettes 25 years ago.
They are using the same themes and the same images but the penetration in the modern media era is as strong as anything we've ever seen."
- Bloomberg