Parents and doctors questioning teens about whether they smoke should also be asking if they're using e-cigarettes, which could be a gateway to nicotine addiction later on, says a pediatrician who led a new study.

Dr. Michael Khoury's research involved nearly 2,300 students in Grade 9 in the Niagara region of Ontario.

Over 10 per cent of them had used electronic cigarettes, said Khoury, though a national report funded by the Public Health Agency of Canada and released earlier this year suggested the rate of Grade 9 students who have tried e-cigarettes is even higher.

"The most common reason that three-quarters of them used it was to be cool, or it was fun and something new," Khoury said about his research. "That's really concerning because they're clearly not using them for what they're marketed as, which is as smoking cessation devices."

Khoury conducted the study while he was a pediatric cardiology resident at the Hospital for Sick Children in Toronto. It was published Monday in the Canadian Medical Association Journal.

E-cigarette use is now more common among adolescents than conventional cigarettes, but the practice that mimics the tactile experience of smoking could also renormalize it for youth who've grown up learning about its effects on health, said Khoury, who is currently completing his residency at Stollery Children's Hospital in Edmonton.

He noted that at least two previous American studies have concluded that youth who use e-cigarettes or "vape" are much more likely to smoke in the future.

E-cigarettes contain a battery, a heating element and a cartridge with a liquid solution that may or may not contain nicotine and other flavours such as cotton candy, peanut butter and jam, and vanilla. Puffing on the e-cigarette heats the solution, creating a smoke-free vapour that is inhaled.

In Canada, e-cigarettes and "e-juice" containing nicotine have not been approved for sale. Nicotine-free vaping products that do not make health claims are legal.

Since the study was conducted, most provinces have created legislation around the sale and marketing of e-cigarettes though there are ongoing calls for the federal government to take regulatory leadership on the issue while balancing the protection of youth and making the product available to adults who want to use it as a way to potentially quit smoking.

Health Canada said e-cigarette products, including liquids containing nicotine, require federal approval before they can be imported, advertised or sold.

"Health Canada continues to advise Canadians, especially youth, against the use of these products," the department said in a statement.

Industry is responsible for ensuring the products it manufactures, imports, advertises or sells do not pose a danger to health, it said.

"The department continues to actively review and monitor health and safety data, scientific studies and the actions of regulators in other jurisdictions."

Khoury said further regulations are needed because e-cigarettes are so appealing to youth, who could be getting a hit of nicotine as they vape, depending on the cartridge they use.

"It's something that's going to become a major public health issue, as it should be, and parents and physicians and schools alike really should put it at the forefront of their agenda."

Prof. Elizabeth Saewyc, who teaches nursing and adolescent medicine at the University of British Columbia, wrote a chapter on substance use among youth in a Public Health Agency report released in March, showing 21 per cent of boys and 15 per cent of girls in Grade 9 have tried e-cigarettes.

"The study in Niagara puts its finger on the nub: It's new, it's electronic, it's cool," Saewyc said.

"Although we've been really good about cigarette smoking to identify the tar in the smoke and how it's bad for your lungs people are looking at e-cigarettes and thinking it's steam, it's not smoke, so it must be safer and forgetting that if it's steam with nicotine involved you still end up with that addiction to nicotine."

Saewyc said it's important for parents to have regular conversations with their children about e-cigarettes, the same as other potentially harmful substances.

David Hammond, associate professor at the School of Public Health and Health Systems at the University of Waterloo, said the federal government must step in with product standards and labelling requirements for e-cigarettes.

"There's no way for consumers to know which manufacturers are acting responsibly, whether the number that's on the label is accurate. And we know they're often inaccurate. Some of them that say they do not contain nicotine actually contain nicotine."

In November 2014, Hammond testified to the House of Commons Standing Committee on Health, which recommended Health Canada establish a common framework to regulate e-cigarettes.