Teenagers who use e-cigs are six times more likely to start smoking cigarettes than someone who hasn’t vaped, ‘scientists’ have said.

An American study has closely followed the smoking habits of 300 teenagers for two years, and it found that 40% of those who had vaped had also tried other tobacco products.

The study backs the US’ anti-vaping tirade, which has been spearheaded by the FDA’s regulation of e-cigs.

The survey began in 2014 and was conducted by the University of South Carolina and, to begin with, around half of the 300 teenagers said they had previously vaped.

One year later, 40% of those who had vaped the year before had also used regular cigarettes.

Teenagers who said they had no intention of smoking in the first study were found to be ten times more likely to move from vaping to smoking in one year.

However, Dr Michael Siegel, a professor from the Boston University School of Public Health, doubted the study, saying there’s no proof vaping prompted teens to smoke and the first survey did not determine how many cigarettes had used e-cigs.

“What’s probably happening is these kids did not become regular vapers, they turned to smoking,” said Dr Siegel. “If they turned into regular vapers, they wouldn’t have turned to smoking.”

It had recently been reported in the US that there’s an increasing amount of teenagers using e-cigs, and less teens are using cigarettes. This doesn’t really provide any support for the USC’s findings, as it implied vapers are six-times more likely to switch to smoking.