However, scientists remain sharply divided on the issue. Critics claim most studies show no connection.
Dr. David Carpenter, Director of the Institute of Health and Environment at the University of Albany, is on one end of the line. Carpenter believes there is evidence that prolonged use of cell phones causes brain cancer. He also believes children are more vulnerable.
Carpenter points to the work of a Swedish researchers who found that if children use cell phones before the age of 20, their risk developing brain cancer goes up five-fold.
"Because the skull is so thin, and the head is relatively small, the radiation penetrates almost through the head. In the adult, it only penetrates a smaller distance. So, the exposure for children is greater than that of an adult," said Dr. Carpenter.
Carpenter will testify before Congress about the dangers of cell phones. However, scientists remain sharply divided on the issue.
Most studies found there was no association between cell phone use and tumors.
"When you have cell next to your ear, the barriers of the bone is just too great for the energy -- the very low amount of energy that comes out of the cell phone," said Dr. Myrna Rosenfeld, neuro-oncologist.
Rosenfeld says the use of cell phones has exploded, but incidents of brain tumors are down. She says it doesn't take a brain surgeon to see the real danger of cell phones.
"People are very distracted on cell phones and they're crossing the street or they're driving. And these are just dangerous situations to be in. And, I think this is the real risk of cell phones," said Dr. Rosenfeld.
Researchers conclude that kids younger than 12 should not use mobile phones except in emergencies. They also say teenagers should use only hands-free devices.