Cell phones emit radiofrequency energy, a type of radiation that is a form of electromagnetic radiation, according to the National Cancer Institute. Though studies are being done to see if there is a link between it and tumors of the brain and central nervous system, there is no definitive link between the two, the institute says on its Web site.

"By all means, if a person feels compelled that they should take precautions in reducing the amount of electromagnetic radio waves through their bodies, by all means they should do so," said Dan Catena, a spokesman for the American Cancer Society. "But at the same time, we have to remember there's no conclusive evidence that links cell phones to cancer, whether it's brain tumors or other forms of cancer."

Joe Farren, a spokesman for the CTIA-The Wireless Association, a trade group for the wireless industry, said the group believes there is a risk of misinforming the public if science isn't used as the ultimate guide on the issue.

"When you look at the overwhelming majority of studies that have been peer reviewed and published in scientific journals around the world, you'll find no relationship between wireless usage and adverse health affects," Farren said.

Frank Barnes, who chaired a recent National Research Council report looking into what studies are needed to assess the health effects of wireless communications, said Wednesday that "the jury is out" on how hazardous long-term cell phone use might be.

Speaking from his cell phone, the professor of electrical and computer engineering at the University of Colorado at Boulder said he takes no special precautions with his own cell phone. And he offered no clear advice to people worried about the matter.

It's up to each individual to decide what if anything to do. If people use a cell phone instead of having a land line, "that may very well be reasonable for them," he said.

Susan Juffe, a 58-year-old Pittsburgh special education teacher, heard about Herberman's cell phone advice on the radio earlier in the day.

"Now, I'm worried. It's scary," she said.

She says she'll think twice about allowing her 10-year-old daughter Jayne to use the cell phone.

"I don't want to get it (brain cancer) and I certainly don't want you to get it," she explained to her daughter.

Sara Loughran, a 24-year-old doctoral student at the University of Pittsburgh, sat in a bus stop Wednesday chatting on her cell phone with her mother. She also had heard the news earlier in the day, but was not as concerned.

"I think if they gave me specific numbers and specific information and it was scary enough, I would be concerned," Loughran said, planning to call her mother again in a matter of minutes. "Without specific numbers, it's too vague to get me worked up."