Public Health England (PHE) recently endorsed the use of electronic cigarettes as an aid to quitting smoking. But in The BMJ this week, experts question the evidence on safety and effectiveness underpinning the recommendations.
Professor Martin McKee at the London School of Hygiene & Tropical Medicine and Professor Simon Capewell at the University of Liverpool, argue that the available evidence about e-cigarettes "suggests that the debate is far from over and questions remain about their benefits and harms."
The PHE report concludes that e-cigarettes are much safer than conventional cigarettes. It also says there is no evidence that e-cigarettes give children a "gateway" into smoking.
Some of the findings have been welcomed by Action on Smoking and Health (ASH) and the Royal College of Physicians of London. But other leading health bodies - including the British Medical Association, the US Centers for Disease Control and Prevention, and the World Health Organization - have expressed caution.
So does the available evidence show clearly that e-cigarettes are as effective as established quitting aids, ask McKee and Capewell.
Unfortunately not. For example, a recent Cochrane review, widely cited in the PHE report, concluded the available evidence was of "low or very low quality" by recognised standards.
And a recent systematic review, which the PHE report surprisingly fails to cite, also found serious methodological problems in many of the studies it reviewed, and noted that one third of the studies (34%) it reviewed were published by authors with conflicts of interest.
The headline message from the PHE report is that "best estimates show e-cigarettes are 95% less harmful to your health than normal cigarettes." Yet McKee and Capewell point out that this figure comes from a single meeting of 12 people, involving several known e-cigarette champions and sponsored by companies with links to the tobacco industry.
The PHE report also asserts that the available evidence suggests that e-cigarettes are not currently re-normalising smoking among children and young people in the UK. But McKee and Capewell point out that experimentation with e-cigarettes among young people in England is "worryingly high" and "this remains a major concern for health professionals and parents."
They describe the report's dismissal of the possibility that e-cigarettes may be a gateway to smoking as "premature." And they argue that the report has many other omissions, such as concerns about product safety, and the lack of evidence of risks from long term dual use with conventional cigarettes.
Finally, the PHE summary states, "The accuracy of nicotine content labelling currently raises no major concerns." Surely, England's leading public health agency cannot be indifferent to a situation in which consumer product information is known to be wildly inaccurate, they ask.
In 2017, the European Union Tobacco Products Directive will come into force, with substantial restrictions on e-cigarettes. "These restrictions will hopefully limit the negative effect of this flawed PHE report," say The BMJ article's authors.
"Meanwhile, directors of public health and the wider community desperately need advice on e-cigarettes that is evidence based and free from any suspicion of influence by vested interests," they conclude.