and they should not be kept directly on the brain or body and that's what the fine print warnings will tell you. >> a lot of people listening to us would say i thought this was studied and if there was something bad, we would know about it. >> studies of the hiroshima bombings know that brain cancer did not show up until 40 years after the bombing owe secured. >> when you put it like that, it seems to make sense that we certainly just don't know, enough time has not passed to say anything definitive on this yet the jury seems to be clear on this. >> i don't think the jury is clear in other nations right now. i think the answer to that has to do with the old fashioned issue, isn't it? the cell phone industry has been very, very powerful and is very influential on both sides of the aisle. all of us including me don't want to give up our phones. >> over ten years, the effect of using a phone would you describe it as a cumulative problem? are you accumulating the problems in your brain? >> it is a cumulative problem. as we know it happens with many things that can cause cancer.