Vaping may not be a gateway to smoking among teenagers after all, according to research.
A new study goes some way to silencing fears e-cigarettes encourage young people to take up the dangerous habit.
Researchers examined data on both smoking rates and attitudes towards cigarettes among 13-to-15 year olds over the past 17 years.
While vaping has skyrocketed in popularity, cigarette use among adolescents has reduced by up to 73 per cent.
The scientists therefore concluded there is 'little evidence' e-cigarettes normalise smoking.
Vaping may not be a gateway to smoking among teenagers, research suggests (stock)
The study was carried out by Cardiff University and led by Dr Britt Hallingberg, a research associate at the school of social sciences.
Co-author Dr Graham Moore, a reader in the school of social sciences, said: 'There was a marginal slowing in the decline in regular smoking during the period following 2010, when e-cigarettes were emerging but relatively unregulated.
'However, these patterns were not unique to tobacco use and the decline in the acceptability of smoking behaviour among youth accelerated during this time.
'These analyses provide little evidence that renormalisation of youth smoking was occurring during a period of rapid growth and limited regulation of e-cigarettes from 2011-to-2015.'
Since the first 'modern' e-cig was invented in the mid-2000s, vaping has become mainstream.
The habit reportedly peaked in 2011 before plateauing in 2013, the authors wrote in the journal Tobacco Control.
Public-health experts remain divided on how safe vaping really is and the extent to which it should be regulated.
While Public Health England has 'supported less restrictive policies', the Center for Disease Control and Prevention in the US has a tighter approach, with vaping being banned in non-smoking places.
Concerns are highest among young vapers after animal studies suggested nicotine impairs brain development.
And a common concern is teenagers who have never smoked may experiment with e-cigarettes after trying vaping.
'Much success in maintaining a continuous downward trajectory in youth smoking in the past 20 years has been achieved through policies that aim to reverse the normalisation of smoking,' the authors wrote.
The flavourings in electronic cigarettes may damage blood vessels in the same way as heart disease, according to research published in June.
The chemicals used to give the vapour flavours, such as cinnamon, strawberry and banana, can cause inflammation in cells in the arteries, veins and heart.
They causes the body to react in a way that mimics the early signs of heart disease, heart attacks or strokes, the study by Boston University found.
Other recent studies have also suggested smoking e-cigarettes could cause DNA mutations which lead to cancer, and enable pneumonia-causing bacteria to stick to the lungs easier.
Researchers at New York University subjected human bladder and lung cells to e-cigarette vapor, which is marketed as being healthier than tobacco.
They found the cells mutated and became cancerous much faster than expected and mice exposed to the vapour also suffered significant DNA damage.
In another study, scientists at Queen Mary University, London, found vaping makes users more likely to catch pneumonia – just like smoking tobacco or breathing in traffic fumes.
The vapour from e-cigarettes helps bacteria which cause the condition to stick to the cells that line the airways, they said.
