NEW YORK, Aug 8 — Young people try electronic cigarettes out of curiosity about the devices and alluring flavours that range from cotton candy to pizza, but keep vaping because of their low cost, according to a study released today.

The report published in the medical journal Paediatrics found that some of the reasons prompting teenagers to try the battery-operated devices, which heat liquids typically laced with nicotine to deliver vapour, help to predict ongoing use.

The most likely draws are the cost, which is much lower than for combustible cigarettes, and ability to vape in places where smoking may be banned, according to the study led by Yale School of Medicine professors. Costs can vary widely, depending on the brand and state cigarette taxes, but savings can add up to thousands of dollars a year for the average smoker, according to various vaping industry estimates.

The ongoing Connecticut-based study was based on surveys in two middle schools and three high schools in the fall of 2013 and spring of 2014. About 340 of the 2,100 students surveyed had used e-cigarettes.

Youngsters who tried vaping to quit smoking were more likely to keep using e-cigarettes months later, the study found. Only about 6 per cent of those surveyed tried e-cigarettes for that purpose, but about 80 per cent of this group stuck with the devices.

More than half the youngsters said they tried the devices because they were curious, 41.8 per cent cited "good flavours” and almost a third because their friends used them. About a quarter said vaping was healthier than traditional cigarettes.

"The younger the kids were when they started, the more likely they were to keep using them,” said Krysten W. Bold, a postdoctoral fellow at the Yale School of Medicine and one of the authors of the report.

The researchers said they hoped policymakers would use the findings to address the growing popularity of the devices, which have prompted warnings about their potential health risks.

"If we could identify early who would still be using e-cigs six months from now, we could intervene at that early stage,” Bold said. — Reuters