E-cigarettes are often billed as a way to give up smoking, or a safer way to enjoy the habit.
But, according to new research, teenagers who use e-cigarettes are significantly more likely to go on to smoke the real thing.
The latest findings are worrying for public health, given they indicate that a new generation could be taking up a habit which is costly for health and the national economy.
Findings come following a study involving more than 3,000 15-year-olds in America.
The latest research has reignited an argument which has been running since e-cigarettes hit the market.
While many family doctors and public health experts are pushing e-cigarettes as a good way to quit smoking, others say that they could actually act as a gateway to taking up the habit.
Because e-cigarettes are often promoted as a lifestyle accessory, there are fears that impressionable teenagers may decide to take up smoking e-cigarettes, believing that they look cool.
In the UK, it is illegal to sell e-cigarettes to people under the age of 18. But, despite these regulations, the number of teenagers using e-cigarettes is said to be on the rise.
Public health officials are pleased that official figures put tobacco smoking among school children at a record low, of 18 per cent. But they fear that the number of teenage smokers could rise again because 22 per cent of schoolchildren have said they have tried e-cigarettes.
The latest study was carried out by the University of Southern California Keck School of Medicine. Researchers found that the more often youngsters use e-cigarettes, the more likely it is that they will turn to tobacco within months.
Researchers carried out a survey of teenagers, asking how often within the past 30 days they had used either e-cigarettes and tobacco cigarettes. They then asked the same question half a year later.
In their conclusions, study authors said:: ‘In this study of adolescents, vaping more frequently was associated with a higher risk of more frequent and heavy smoking six months later.’
Those who said they frequently used e-cigarettes at the start of the study were much more likely to have taken up smoking six months later, with 11.6 per cent saying they smoked tobacco occasionally, and nearly a fifth saying they were frequent smokers.
New laws introduced by the EU earlier this year banned TV advertising of e-cigarettes because of the perceived risk to children and young people.