PITTSBURGH -- It’s hard to imagine living without them.

A recent statistic puts cell phone ownership at 90 percent among Americans.

Yet, technology presents a double-edged sword.

The Food and Drug Administration cites three studies since 2000 that have shown no harmful effects from cell phone use.

In a recent appearance on CNN’s “Larry King Live,” Dr. Michael Thun, of the American Cancer Society, agreed.

“We know that the studies that have been done on brain cancer -- and I’m gong to distinguish brain cancer from acoustic neuroma -- have largely been reassuring,” Thun said.

Dr. James Wilberger, the chairman of Neurosurgery at Allegheny General Hospital, thinks the concern has been overblown.

“The true science has been done. It has not shown any connection so far, although the longest studies go out only 10 years,” Wilberger said.

Dr. Frank Lieberman, a neuro-oncologist at the Hillman Cancer Center, uses a speaker phone for short conversations when he can and an earpiece for longer periods.

“It has facilitated the practice of medicine,” Lieberman said. “It is a lot easier to be on call.”

Dr. Ron Herberman, director of the University of Pittsburgh Cancer Institute, does the same thing.

“It was really when I saw the recommendation from the French government to be very cautious in the use of cell phones, and the array of different experts that weighed in on this, that I took this very seriously,” Herberman said.

Dr. Devra Lee Davis, an environmental oncologist, believes the lack of definitive studies on long-term exposure presents a problem.

“The absence of evidence that cell phones cause brain cancer now should not be interpreted as proof that there is no problem,” Davis said. “What that means is we haven't waited long enough to know the answer to the question.”

“I can't tell you cell phones are safe, and I can't tell you that they are harmful. What I can tell you is that they get into the brain. They get more deeply into the brain in children than adults,” Davis said. “I do not think anyone should stop using cell phones -- children should not be using cell phones as several countries now recommend.”

Davis and an international expert panel have developed 10 precautionary recommendations.

1. Don’t give cell phones to children 2. Do use a speaker phone or earpiece 3. Don’t carry a phone on your body 4. Put keypad facing body 5. Avoid use in crowded places 6. Keep conversations short 7. Switch sides regularly 8. Avoid using when signal is weak 9. Text to limit exposure 10. Choose a low Specific Absorption Rate (SAR)

“I don't keep it turned on on my hip, which I used to do like most people in the beginning,” Davis said. “When it is on and it rings, and you answer, you are getting a signal, into your bone -- your bone marrow.”

“Dr. Herberman is calling for cell phone companies to release data on the records of cell phones, so we can actually do the studies that need to be done,” Davis said. “Without that, we can't do the work.”