Teenagers who have used e-cigarettes by the time they start ninth grade are much more likely to take up combustible tobacco products like cigarettes, according to a study funded by the National Institutes of Health.

The study likely will support claims that use of vaping products by youths represents a gateway to smoking. “While we cannot conclude that e-cigarette use directly leads to smoking, this research raises concerns that recent increases in youth e-cigarette use could ultimately perpetuate the epidemic of smoking-related illness," said Dr Adam Leventhal, lead author of the study and director of the Health, Emotion and Addiction Laboratory at the University of Southern California.
A sample of 2,530 students entering the ninth grade (aged 14-15) at 10 public schools in California were surveyed, of which 222 responded they used e-cigarettes and 2,308 said they did not. In the following six months, 30.7 per cent of the e-cigarette users began using cigarettes and other combustible products. Only 8.1 per cent of the non users said they had started smoking. In the following six months, 25.2 per cent of the e-cigarette group said they had smoked versus 9.3 per cent in the non-user group.