A senior scientist has criticized health officials for promoting "e-cigarettes," despite growing evidence of their damage.
Professor Martin McKee of the London School of Hygiene and Tropical Medicine said there was "serious concern" about e-cigarettes.
Public Health England (PHE), however, recommends that they be prescribed in the NHS, controversially claiming that they are 95 percent less harmful than cigarette smoking.
Last year she campaigned for smokers to switch to e-cigarettes, also as part of her annual "Stopover" campaign.
Earlier research has shown that e-cigarettes can damage the blood vessels and possibly the heart by causing inflammation (swelling) that, if persisting for a long period of time, can cause permanent tissue damage at the Vape Jam show in London at the beginning of this month)
Professor McKee, a long-standing critic of device advertising, said PHE "is doing everything it can to promote e-cigarettes," ignoring global warnings about the risks.
He said, "The nicotine in e-cigarettes is not a harmless drug and then there are all these other things, like flavorings that are inhaled.
"We did not have enough e-cigarettes to know the true effects. However, if we look at the evidence we have, there is enough cause for serious concern.
"Given the short-term effects on lung function and cardiovascular effects, there is enough evidence that we should be very, very careful."
The expert added, "It's not that e-cigarettes are safer than cigarettes, but whether they're safe."
Many scientists are concerned about the safety of e-cigarettes, which are feared to be very attractive to young people and have been used by around three million British adults in the past decade.
In the United States, the authorities have threatened to remove steam and e-cigarettes from the shelves unless manufacturers do more to curb the consumption of teenagers.
The devices contain a liquid form of nicotine that is heated to be inhaled into a vapor, thus avoiding the risk of lung cancer from tobacco smoke.
HOW CAN THE STEAM BE HARMFUL?
According to a study published in June, flavors in electronic cigarettes can harm blood vessels as well as heart disease.
The chemicals used to add flavor to the steam, such as cinnamon, strawberry and banana, can cause inflammation in the cells of the arteries, veins and heart.
They cause the body to react in a way that mimics the first signs of heart disease, heart attacks, or strokes, according to the Boston University study.
Other recent studies have also suggested that smoking e-cigarettes could cause DNA mutations that lead to cancer and facilitate the attachment of pneumonia-causing bacteria to the lungs.
New York University researchers exposed human bladder and lung cells to e-cigarette vapor, which is marketed as healthier than tobacco.
They found the cells mutated and became cancerous much faster than expected. Mice exposed to the vapor also suffered significant DNA damage.
In another study, scientists from Queen Mary University, London, found that vapors increase the likelihood of pneumonia – as does smoking tobacco or inhaling traffic smoke.
The vapor of e-cigarettes helps bacteria, which cause the condition to adhere to the cells of the respiratory tract.
The effect occurs in traditional cigarette smoke and in people exposed to air pollution from particles of vehicle exhaust.
However, diacetyl used in e-cigarette flavors can lead to an incurable condition called "popcorn lung".
Animal studies have linked electronic cigarettes to certain types of cancer and heart disease.
Last year, a study conducted by the University of Birmingham found that vaping damages inflammatory chemicals in the airways.
Over time, this can lead to COPD – the generic term for chronic respiratory diseases such as bronchitis and emphysema.
Dr. Aaron Scott, who led the study, said, "We do not know what the long-term data are, but we've shown that it's cytotoxic and anti-inflammatory, just as cigarette smoke is short-term."
Both Dr. Scott and Professor McKee have expressed concerns that e-cigarettes may appeal to young people despite a ban on buying under-18s.
Professor McKee warned that adolescents were addicted to juul, an e-cigarette blamed for childhood nicotine dependence in the US, and launched on the UK market last summer.
He said, "It is now very clear that these products are very much pushed for children.
"This leads to a completely avoidable risk of a new generation dependent on nicotine addiction."
Dr. Scott said, "You can go to a pound store anywhere in the country and buy 1 pound of e-cigarette fluid. You can do this with very little regulation, for example it is very easy for children to achieve that – it is very easily accessible. "
A February report from PHE showed that the number of Vaping children doubled between 2014 and 2018, from 8.1 to 15.9 percent for 11 to 18-year-olds.
Professor McKee said to tobacco companies: "The companies are trying to become socially acceptable.
"They were international pariahs and are now trying to present themselves as part of the solution."
Public Health England has claimed that "false fears" of fumes discourage thousands of people from using them.
Professor John Newton, Director of Public Health Health Improvement, said: "There is widespread academic and clinical consensus that, while vapors are not risk-free, they are far less harmful than smoking.
"This view is shared by many around the world, including the Royal College of Physicians, Cancer Research UK, the British Medical Association, and the National Academy of Sciences in the United States."
He added, "We are aware of the risks, and the UK has taken a careful approach to maximize the chances of e-cigarettes to help more smokers exit."
Professor McKee said, "PHE seems to ignore the risks of e-cigarettes, especially the risks to cardiovascular disease.
"At a very early age, this figure has set that electronic cigarettes are 95 percent safer than smoking, which is very difficult.
"But there's more and more evidence that this is not the case as PHE continues to promote e-cigarettes in advertising."