The vast majority of New Zealand-based online sellers of vaping products don't check the buyers' age, new research has found.
Health researchers are calling for better age verification systems to stop more kids taking up the habit, with the long-term health effects completely unknown.
Researchers at the University of Otago's Department of Public Health analysed dozens of the most popular local e-cigarette vendors operating online, and found only 10 percent of them - six out of 59 - required proof of age before buying, such as a driver's licence or passport.
Nearly half of them - 28 - just asked buyers to click a box to confirm their age, while another 24 didn't check for ages at all.
One site only required a credit card number, but children under 18 can get those through their parents or use a debit card number, which some banks issue to kids as young as 13.
"There's virtually no protection for children and young people," said associate professor George Thomson. "There's no age proof, or very little."
The researchers say a Government-run ID scheme might be the answer. They're already in place in some overseas jurisdictions to keep kids off gambling sites.
"With the known side-effects of nicotine on brain development during the adolescence period, and evidence that [e-cigarette] use may be related to smoking initiation, an effective age verification process seems essential," the study, published in the New Zealand Medical Journal on Friday, said.
Most of the sites looked at also had a heavy presence on social media, running promotional material - such as pictures to illustrate flavours - that would break the law if they were advertising traditional nicotine cigarettes.
"New Zealand vendors who marketed [e-cigarettes] during the time we collected data were largely unaware of or did not follow existing legislation and Ministry of Health guidance," the study said.
"This gap between policy-makers' expectations and marketing practices suggests that regulations could focus on mandating health and addiction warnings, requiring effective age verification, and reducing the widespread availability of flavours likely to appeal to young people."
Only one of the 53 YouTube videos featured on the vendors' sites required a sign-in to verify the viewer's age. Only one-third of their sites displayed health warnings, and only one mentioned a possible risk for pregnant and/or breastfeeding women.
Thomson says most flavours advertised are also sweet, which are particularly attractive to youth.
"If vaping is to help smokers to move from smoking to vaping - as a temporary thing of becoming nicotine-free - then I have seen no arguments they need sweet and dessert flavours."
Smaller retailers told RNZ in August they were ramping up advertising efforts in the wake of big tobacco companies getting into the vaping market.
"It's become clear, with how aggressive the tobacco companies are being, we can't sit back - we have to take them head-on," VAPO director Jonathan Devery told the station.
Complaints about vaping ads are also on the rise. Earlier this month myblu - owned by Imperial Tobacco - was rapped over the knuckles by the Advertising Standards Authority for implying vaping was a completely safe activity.
There have been a string of deaths in the US linked to vaping - but it's believed black market THC products are to blame, not conventional e-cigarette liquid.
"To my knowledge, no cases have been found in people who vape regular main brand e-liquid or pod-based products such as JUUL," said Chris Bullen, a professor of public health at the University of Auckland.
The Ministry of Health says vaping has the "potential" to improve public health.
"Smokers switching to vaping products are highly likely to reduce the risks to their health and those around them," its website reads.
A New Zealand study in 2015 found a typical e-cigarette sold in New Zealand has about 0.5 percent the toxicity of a typical cigarette.
But as e-cigarettes are a relatively new invention, having only entered the market a little more than a decade ago, their long-term impacts remain a mystery.
"There is no point continuing to debate whether e-cigarettes are more or less harmful than conventional cigarettes; this is only delaying the implementation of vital regulations – needed now – and increasing our understanding of the long term effects of vaping," said Kelly Burrowes of the University of Auckland's Bioengineering Institute.
"It is clear that there is a large population of youth starting to use e-cigarettes worldwide and it is, or should be, hard to ignore that many scientific studies are showing cytotoxic, pro-inflammatory, genotoxic effects and effects on the respiratory function of users."