Electronic cigarettes have gained considerable popularity over the past few years - for most they are another form of the nicotine patch, and a way to curb harmful cigarette smoking but critics contend they make smoking cool.

No one thinks they are cool, they are in Google Glass territory among the public, just a moment away from leading to insults, so research instead focuses on the well-documented health benefits of smoking less versus any possible risks.

Governments want to regulate them to generate revenue so the onus is on the industry to try and prove they are safe, an impossible task. Yet if they show they are not harmful, it will be harder to convince the public they should regulate those when alternative medicine is unchecked.

A new review of studies on the use, content, and safety of e-cigarettes has concluded that, compared with conventional cigarettes, they are likely to be much less harmful to users. Obviously they can't harm bystanders. Potential long-term health effects of e-cigarette use are obviously unknown but existing literature does not list nicotine as the harm, it lists smoking, that is why patches are socially acceptable.

The review carried in Addiction concludes that despite gaps in the knowledge which require further research, the current evidence about e-cigarettes does not justify regulating them more strictly than, or even as strictly as, conventional cigarettes. Regulatory decisions will provide the greatest public health benefit when they are proportional, based on evidence, and incorporate a rational appraisal of likely risks and benefits.

The scientific review was conducted by an international team of tobacco researchers and led by Queen Mary, University of London Professor Peter Hajek, who says, "The evidence we currently have is clear: e-cigarettes should be allowed to compete against conventional cigarettes in the marketplace. Health care professionals may advise smokers who are unwilling to cease nicotine use to switch to e-cigarettes. Smokers who have not managed to stop with current treatments may also benefit from switching to e-cigarettes."