E-cigarettes are more harmful than regular tobacco with 10 times the level of cancer-causing carcinogens, Japanese scientists have claimed.
The electronic nicotine products have increased in popularity with many believing that they are receiving a hit of nicotine without the health damage of a normal cigarette, laden with chemicals.
However, the research commissioned by the Japanese Ministry of Health found formaldehyde and acetaldehyde carcinogens in the liquid produced by a number of e-cigarette products, a health ministry official told AFP.
The formaldehyde carcinogen was found to be much more present in the e-cigarette liquids than in the chemicals used in regular cigarettes, according to the official.
"In one brand of e-cigarette the team found more than 10 times the level of carcinogens contained in one regular cigarette," said researcher Naoki Kunugita.
"Especially when the... wire (which vaporises the liquid) gets overheated, higher amounts of those harmful substances seemed to be produced."
However, Kunugita added that the levels of the formaldehyde carcinogen fluctuated in the final results.
"You call them e-cigarettes, but they are products totally different from regular tobacco," the Japanese health ministry official said.
"The government is now studying the possible risks associated with them, with view to looking at how they should be regulated."
Earlier this year, the World Health Organisation (WHO) urged governments to ban the sale of e-cigarettes to minors because of the "serious threat" posed to them.
The UN health agency said that despite the lack of evidence on the damage caused by e-cigarettes, there was enough "to caution children and adolescents, pregnant women, and women of reproductive age" about their use, adding that they should be outlawed from indoor public spaces.