Nightly News | February 22, 2011
>>> finally here tonight, it's not a happy story to end on, but we have a lot of news tonight. this one's been talked about and whispered about. it's always been the fear about cell phones . when held up to the ear, do they cause brain cancer ? although the science isn't clear, a lot of people long ago made the switch to hands free devices. tonight while not definitive, there is some intriguing new research about what happens in the human brain when using a cell phone . here with the story, robert bazell .
>> it's the first time scientists have measured changes in the brain caused by radiation from cell phones .
>> this area that you have here.
>> the director of the study of the national institutes of health says there's no evidence of health effects , but she stillmans to change how she uses her cell phone .
>> i can use my cell phone with a wired ear piece or i can text.
>> reporter: researchers placed cell phones on mute. but still transplants signals next to the heads of users for 50 minutes. the cell phones increased temporary activity. they light up the same thing when someone has a thought, moves a toe, sees the light or carries out any function controlled by the brain. other brain scan experts are not so concerned.
>> there's nothing in this paper that suggests cell phones have any adverse effect or any harmful effect on the brain.
>> reporter: most physicists who study radiation have always said that cell phones could not cause brain tumors or other health problems.
>> the cell phone doesn't emit enough power to be damaging to the human body .
>> reporter: the cell phone industry also says there's no evidence of danger, many people remain concerned. cell phone use in this country alone has grown from 4 million in 1990 , to almost 300 million last year. the latest finding calls for more research. feeding a concern is that shows no sign of letting up in our evermore wireless society. robert bazell , nbc news, new york.