The head of a prominent cancer research institute issued a warning to his faculty and staff Wednesday to limit cellphone use because of the possible risk of cancer.

The warning from Dr. Ronald B. Herberman, director of the University of Pittsburgh Cancer Institute, is contrary to numerous studies that do not find a link between cancer and cellphone use, and a public lack of worry by the U.S. Food and Drug Administration.

Although Herberman is basing his concerns on early unpublished data, he says it takes too long to get answers from science and believes people should take action now – especially when it comes to children.

"Really at the heart of my concern is that we shouldn't wait for a definitive study to come out, but err on the side of being safe rather than sorry later," Herberman said.

No other major academic cancer research institutions have sounded such an alarm about cellphone use. But Herberman's advice should raise concern among the many cellphone users and especially parents around the nation.

In the memo he sent Wednesday to 3,000 faculty and staff, he says children should use cellphones only for emergencies because their brains are still developing.

He encourages adults to keep the cell phone away from the head and if possible use the speakerphone or a wireless headset.

He even warns against using cellphones in public places like a bus because it exposes others to the phone's electromagnetic fields. Electromagnetic radiation is the main concern from many scientists, especially the potential effects it can have on young children.

A 2008 University of Utah analysis looked at nine studies with thousands of brain tumor patients and the results conclude there was no overall increased risk of brain tumors among cellular phone users. But, the potential elevated risk of brain tumors after long-term cellular phone use awaits confirmation by future studies. Studies conducted last year in France and Norway show the same results.

"If there is a risk from these products – and at this point we do not know that there is – it is probably very small," the Food and Drug Administration says on an agency web channel.

Still, Herberman cites a "growing body of literature linking long-term cellphone use to possible adverse health effects including cancer."

"Although the evidence is still controversial, I am convinced that there are sufficient data to warrant issuing an advisory to share some precautionary advice on cell phone use," he wrote in his memo.