While cellphones are increasingly popular among kids, some scientists worry the devices are a health risk to them.

The World Health Organization is completing a massive study to see if there's a link between cellphone use and brain cancer and other ailments.

Cellphones emit electromagnetic radiation. Their design requires them to be held tight to a person's head.

Scientists are concerned that childrens' skulls are thinner and their brains are still developing. Therefore, the risk of electromagnetic energy damaging their brains could be greater than the risk for adults.

There are ways to reduce the risk, said a WHO spokesman.

"With respect to children, WHO recommends that children should use hands-free headsets," said Mike Repacholi.

"I have a headset, actually," one youngster told CTV News. "I use it when I'm biking."

"It's a decision for them and their parents to make together," said Peter Barnes of the Canadian Wireless Telecommunications Association about cellphones and kids.

Barnes said if children limit their cellphone use to an hour per day, there should be no problems.

One reason for concern is that the wireless industry is increasingly targeting children, coming out with Barbie or Hello Kitty-themed products.

The Canadian research team contributing to the project has access to the phone records of cancer patients -- and some of them are kids.

"And if we're looking at chronic diseases like cancer, because they are exposed at an earlier age, they have a greater opportunity for that effect to manifest itself," said Daniel Krewski, who added there is no evidence so far that kids are at risk.

Globally, the wireless industry predicts 1.6 billion cellphone customers in 2005. About 15 million Canadians are believed to use them.

The cellphone industry in this country claims to employ 25,000 and generate about $10 billion in annual business.

"Given the immense numbers of users of mobile phones, even small adverse effects on health could have major public health implications," the WHO said.

Kids and cancer aren't the only focuses of the study, which will also look at conditions like memory loss and other decline in mental functioning.

The study is also examining the questions of whether people can safely use cellphones while driving and how much they interfere with medical devices.

The report should by completed by year's end.

With a report from CTV's Rosemary Thompson