ABC NEWS 
Feb 23, 2011
Fears concerning the possible dangers of prolonged cell phone use won’t go away, despite numerous studies showing no conclusive link between cell phones and brain tumors or cancer.
Now new data from the National Institutes of Health suggesting that cell phone radiation boosts brain activity is poised to stir the debate even further.
Researchers used PET scans to measure brain activity in 47 participants when they had cell phones held to their ears in both off and on but muted positions and found that exposure to an in-use cell phone for more than 50 minutes increased brain activity by about 7 percent in the regions closes to the antenna.
This suggests that while no link has been proven between adverse health effects and cell phone radiation, the human brain is sensitive in some way to the electromagnetic waves coming off of a cell phone.