cell phones, most of us use them. are they really safe? do they cause cancer? the government and the cell phone industry say no, the fine print on cell phone packaging says maybe. but some leading scientists and doctors say we should be concerned. especially for our children. our chief medical correspondent dr. sanjay gupta has been looking into this and joins me now. i guess the key question on everybody's mind, how concerned should we really be? >> it's a good question. perhaps more concern than the headlines have you believe. the phone study was this big study, 13 countries participated. the headline was there's no association. what we found by digging deeper, though, randi, into this, there's an appendix to this study which you could only find online. once you looked at that, here's what i thought was interesting president people who use their