The e-cigarette – the smoking alternative that has gone from nothing to a sprawling, unregulated multibillion dollar business in less than a decade – could be “no better” than traditional cigarettes, according to a new study.

Research published in the Journal of Oral Oncology claims to have demonstrated that vapour from the electronic devices may damage DNA or even kill human cells in laboratory experiments.

The study, which its authors admit is inconclusive, comes after public health officials in Europe, the US and the UK have backed the use of e-cigarettes to help people quit smoking.

Tobacco remains one of the great public health hazards. In Britain, an estimated 2.6 million people now vape, and e-cigarettes will be licensed and regulated in 2016 as aids to break the tobacco habit.

Scientists in the latest study, based in the US, established that cells treated with nicotine vapour are more likely to be damaged or die than those exposed to a nicotine-free variety.

They concluded: “Our study strongly suggests that electronic cigarettes are not as safe as their marketing makes them appear to the public.”

One senior author, Jessica Wang-Rodriguez, a pathologist with the San Diego branch of the US Department of Veteran Affairs, said: “Based on the evidence to date I believe they are no better than smoking regular cigarettes.”

Very few public health chiefs are likely to agree with her. The e-cigarette business has grown rapidly in recent years, with a recent study of internet marketing finding that 10 new brands and around 240 new flavours were being introduced each month.

The evidence allegedly proving or disproving the health impact of e-cigarettes so far is up for debate. One study this year compared lung damage from tobacco smoke and from e-cigarette vapour and concluded that the vapour version had “no cytotoxic impact” on human airway tissue. It was conducted by British American Tobacco scientists.

The University of Rochester found that emissions from flavourings in e-cigarette aerosols could deliver free radicals, heavy metals and inflammation agents to the lung tissue.

Meanwhile, a risk assessment conducted by the Norwegian Institute of Public Health concluded that since e-cigarettes delivered the same amount of nicotine as cigarettes, the same harmful effects could be expected. But almost all conceded that the risks were lower than those from lighting up a cigarette.

Kevin Fenton, national director of health and wellbeing at Public Health England, said health chiefs would keep looking at new evidence but defended e-cigarettes as being less harmful.

“Our recent world-leading review found that e-cigarettes carry a fraction of the risk of smoking – the harmful chemicals found in tobacco smoke, including carcinogens, are either absent in e-cigarette vapour or are at significantly lower levels than in tobacco smoke,” he said.

“The best thing a smoker can do is quit completely, now and forever, and we need to provide smokers with accurate, balanced information on different quitting methods.”