A report by Toronto Public Health advises children to limit their use of cell phones as much as possible, citing studies that have linked long-term mobile phone exposure to an increased risk of brain tumors.

"We think it's responsible to limit children's exposure," the researchers wrote.

"While scientists were pretty dismissive of any risk years ago, with the accumulation of studies, it appears people who have been using their phones for a long period of time are at greater risk of certain kinds of brain tumors." said report co-author Loren Vanderlinden.

Toronto Public Health recommends that children use land lines whenever possible, using mobile phones only for "essential purposes." When cell phones are used, the report urges children to keep calls shorter than 10 minutes and to use headsets or other hands-free devices as much as possible. Limiting cellular phone use is especially important for pre-adolescents, the authors said.

"Teach [children] the ways to use a cell phone responsibly," Vanderlinden advised parents. "To make shorter calls, to use other modes of communication; if it's possible, use a landline."

Researchers suspect that the thinner skulls and smaller heads of children place them at greater risk than adults from the same degree of mobile phone radiation. Indeed, some studies have confirmed that cell phone radiation penetrates deeper into the brains of children than adults.

The use of cellular phones has dramatically increased in Canada over the last 10 years, particularly among children. Approximately 61 percent of children between the ages of 12 in 19 now use mobile phones. The numbers for children under the age of 12 are not known.

The Toronto warning is the first warning against cellular phone use in Canada, and is similar to warnings that have been issued in Belgium, England, France, Germany and Russia. Health Canada, the country's public health agency, said it had no plans to follow Toronto's lead.