A World Health Organisation-commissioned review of e-cigarettes contains errors, misinterpretations and misrepresentations, meaning policymakers may miss their potential health benefits, a group of tobacco addiction experts said.
In a critique of the WHO's background paper on e-cigarettes, which acted as a blueprint for a WHO report last month calling for more regulation of the devices, the experts said its evaluation of the evidence was inaccurate.
"I was shocked and surprised when I read it," Ann McNeill, a researchers at the national addiction center at King's College London, told reporters at a briefing. "I felt it was an inaccurate portrayal of the evidence on e-cigarettes."
The uptake of e-cigarettes, which use battery-powered cartridges to produce a nicotine-laced vapor, has rocketed in the past two years, but there is fierce debate about their potential risks and benefits.
Because they are new, there is a lack of long-term scientific evidence on their safety. Some experts fear they could lead to nicotine addiction and be a gateway to tobacco smoking, while others say they have enormous potential to help millions of smokers around the world kick their deadly habit.
The WHO's report last month called for stiff regulation of e-cigarettes as well as bans on indoor use, advertising and sales to minors.
McNeill said that while e-cigarettes are relatively new and "we certainly don't yet have all the answers as to their long-term health impact", it is clear they are far safer than cigarettes, which kill more than six million people a year.
Peter Hajek of the tobacco dependence research unit at Queen Mary University of London, who co-authored the critique, said it was vital that e-cigarettes should be assessed in relation to the known harms of tobacco cigarettes.
"There are currently two products competing for smokers' custom," he said. "One - the conventional cigarette - endangers users and bystanders and recruits new customers from among non-smoking children who try it.
"The other - the e-cigarette - is orders of magnitude safer, poses no risk to bystanders, and generates negligible rates of regular use among non-smoking children who try it."
Yet the WHO's background paper, and its report last month, recommend making it harder to bring e-cigarettes to market, and have the potential to put smokers off them, the experts said, putting policymakers and the public in danger of foregoing the public health benefits e-cigarettes could have.
"The use of e-cigarettes could save millions of lives during this century, and have the most important public health impact in the history of tobacco use," said Jacques le Houezec, a co-author and consultant in public health and tobacco dependence in France and lecturer at Britain's Nottingham University.
McNeill and her co-authors, whose critique was published in the journal Addiction, focused on several key statements in the WHO-commissioned review which they said were misleading:
* The review implied e-cigarette use in youth is a major problem and could be acting as a gateway to smoking, they said, when in fact current use by non-smokers is extremely rare and youth smoking rates are declining.
* The review fails to acknowledge that e-cigarettes are not just less harmful than tobacco cigarettes but that the concentrations of toxins are mostly a tiny fraction of what is found in cigarette smoke.
* The review infers that bystanders can inhale significant levels of toxins from the vapour, when the concentrations are too low to present a significant health risk.
* And the review gives the impression that evidence suggests e-cigarettes make it more difficult for people to stop smoking, when the opposite is true, the experts said.
They also criticized the WHO-backed reports for "using alarmist language to describe findings and to present opinion as though it were evidence."
This latest critique follows an editorial this week in the British Journal of General Practice by public health experts from University College London (UCL), who argued that health messages about e-cigarettes should be based on facts.