around the international spaceation, mike fink and drew foystyl, at this for the past five hours, when the space walk started. what you are seeing right now is a live picture we can bring you happening at the intersenate space station. i'll be back with you at the top of the hour. right now time for the good doctor. hello, i'm dr. sanjay gupta. welcome to the show. today i'm taking a closer look at something that's become so closely woven into our lives it's hard to imagine what we would do without it. i'm talking about our cell phones. most of us take it for granted that they're safe and that may be the case. but i've also spent the last several months investigating and talking with people who say don't be so sure. some of you may already be rolling your eyes. i understand that. i want you to stick with me this half hour. we've been digging a little deeper to try to get a more definitive answer. i will tell you this, it wasn't easy.

what surprised me is voices urging caution are not only getting louder, but they're getting more prominent. >> all right. i'm on my way. >> if you've ever put a cell phone to your ear, you should listen to what neurosurgeon dr. keith black has to say. >> there's no way to say that cell phone use is safe. i think the public has a right to know there could be a potential risk. the public generally assumes that if one is selling something on the market, that we have had assurances that that device is safe. >> to be clear, dr. black's message is at odds with headlines from the largest international study on cell phones and cancer. their conclusion, little or no evidence cell phones are associated with brain tumors. if you look just one layer deeper into the appendix of that same study, you'll see something unsettling. turns out participants in the study who use a cell phone for ten years or more had double the

rate of a type of tumor. keep in mind cell phone use in the united states has only been popular for around 15 years. in 1996, there were 34 million cell phone users. today, nearly 300 million in use according to industry figures. >> environmental factors take decades to see their effect and not a few years. >> if it may take decades to get a clearer answer, what can we say about cell phone safety now? scientists here in san jose, california, are trying to answer that very question. >> one of the things we have to do first is literally put the brain inside the head. >> exactly. it's very light now. >> the fcc requires all cell phones emit 1.66 watts of radiation. they try to mimic the human rain with salt, sugar and water. let me show you precisely how

they do this test. this is a model. this is supposed to approximate the human skull of an adult male. this is my phone attached there connected at the angle that most people would speak with. and inside over here very important this bubbly liquid inside that represents liquid brain. what's going so happen is the phone makes a call after a period of time this dwis will come over here and measure radiation at all sorts of different points in the brain. after that they will take all of those numbers and basically put it on a computer screen and tell us where the hot spots are and just how high the levels got. my cell phone measured within fcc limits. the whole process was surprisingly low tech. and what about different size skulls or children? >> in children their skull is thinner, their scalp is thinner so the microwave radiation can penetrate deeper into the brain of children and young adults and their cells are

dividing in a much faster rate so the impact of microradiation can be much larger. >> there have been no studies on children and cell phone safety. here's something else that might surprise you. the cell manufacturers themselves advise against putting the cell phone right next to your head or really anywhere on your body. look with the iphone 4. safety instructions say when using the iphone near your body for voice calls keep it 15 millimeters away from your body. blackberry users specifically have safety guide lines saying keep it .98 inches or 25 millimeters from your body meaning your head or your pocket. dr. keith black has been talking about this longer than many but the voices joining him are becoming louder and more prominent. the city of san francisco pushed for radiation warning labels on cell phones. the head of a prominent cancer research institute sent a memo to all employees urging them to limit cell phone use because of possible risk of cancer. the european environmental

agency has pushed for more studies saying cell phones could be as big a public health risk as smoking and leaded gasoline. the federal communications commission, the fcc, they set the guidelines for how much radiation a cell phone can emit and they say cell phones are safe. how can they be so sure? keeping them honest, we decided to come here to try to find out for ourselves but they declined an on-camera interview. the type of radiation coming out of your cell phone is called non-ionizing. it's not like an x-ray but more like a low powered microwave oven. >> what microwave radiation does in the most simplistic term is very similar to what happens to your food when you put your food in a microwave oven. it's essentially cooking the brain. >> based on past statements, the fcc isn't convinced there's a real risk and maintain they do

not endorse the need for consumers to take any precautions to reduce exposure. i tell you as a neurosurgeon and journalist and a guy that has three cell phones, i believe this is an important issue to investigate. for what it's worth, i haven't met anyone that says don't use a cell phone. that's not even realistic in today's age. there are things you can do, steps you can take to minimize your risk from radiation. if you are concerned about that, i'll show you those during the show. coming up first, we'll dig even deeper into this and you'll hear my conversation with a scientist who has been studying this for over 20 years. i'll be right back with a special look at cell phone safety. okay, team! after age 40, we can start losing muscle --

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public, private, even hybrid. your data and apps must move easily and securely to reach many clouds, not just one. that's why the network that connects, protects, and lets your data move fearlessly through the clouds means more than ever. we're back with a special "sgmd" talking about cell phone safety. there's been a lot of studies on this. the most recent study on cell phones is by researchers at the national institutes of health. they found something very interesting. the radiation emitted from your cell phone increased brain cell activity after 50 minutes of talk time. let me show you what i'm talking about here. these are natural scans of the brain looking at what's known as

glucose metabolism. one way of measuring brain activity. this is with the cell phone on. look at the yellow around the brain compared to when the cell phone is off, very little yellow comparatively speaking. it shows there's an impact from using cell phones actually on the brain. we don't know if it's good or bad right now. these are preliminary findings. there may be concerns among people who already have some sort of brain problem. for example, someone has a brain tumor you can see increased glucose metabolism because cancer is high activity part of the brain and could that worsen it somehow. that's the questions that researchers at nih raised and that's part of the speculation overall. they say they are committed to studying it further. it all comes back to a question of safety. i should tell you now right off the bat what we're talking about today is highly controversial. we've talked to industry experts who say that scientific evidence has overwhelmingly indicated that wireless devices do not pose a public health risk. i talked to a lot of scientists

and doctors who say, look, we just don't know and then there are people like devra davis, a physician, a reverender is, former white house senior health adviser, who founded a group called environmental health trusts. she studied the issues with cell phones for decades and the amount of radiation they give off and what your body might absorb trying to connect those dots. you may not agree with what you're about to hear and what she has to say, but i think it's important to hear. why did you get interested in cell phones? >> i knew about the history of tobacco and asbestos. because i'd worked on those things for 20 years. >> just because there are other issues that subsequently became problematic, it doesn't mean everything is going to become problemat problematic. >> in this case i knew enough to look at effects that haven't been appreciated and when i looked back and looked at the history of science, which is something i know a little bit about, i learned that the navy had had warnings and had developed ways to protect personnel against exposures and i became curious. >> as you talk about and a lot

of people do, everybody has one nowadays. young kids are using them. >> i prefer to think that we were naive and the reason we're talking about is that we're no longer naive about this issue and i think there is a recognition also is that the governments of france answer israel have issued warnings and those are countries not known to take these issues lightly. i'm particularly concerned as a grandmother about the developing brain, about children who are using cell phones, about toddlers and infants whose parents are downloading white noise apps and lullabies and putting the phones by their heads. we are so naive about technology. cell phones have revolutionized our lives. you can respond to medical emergencies, they're valuable but people have a right to know that cell foephones are basical small two-way microwave radios 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. it may not be the one exposure. we are born with repair processes.

we get damage to our dna every day by breathing, sunlight and whatnot. if we eat well and exercise and don't have too much exposure, that damage gets repaired. for cell phone radiation, young people today are growing up in a sea of radio frequency radiation that didn't exist even five years ago. >> we've been surrounded by radiation for a long time. you're saying this new radiation has changed the amount that we're exposed to? >> by billions and billions and billions of times. the amount of radio frequency radiation today is billions and billions of times greater than occurred at the big bang with which we evolved human life. i don't think all make waive radiation is necessarily problematic, and i recognize that microwaves play a very important role in many aspects of modern life. but i think direct microwave radiation of the brain and that's why all of the fine print warnings advise don't hold the phone directly on the body.

the test system for testing phones today which gives you the specific absorption rate uses a spacer here for every millimeter away from the brain you get a 15% reduction in radiation to the body. >> what's the worst case scenario? if you extrapolate numbers you just talked about, how bad could this be? >> it could be a global epidemic. people have a right to know there are simple things to do. you have to have more of a public conversation about this. we are poorly served by reassurances that everything is okay by misuse of science. it's not helping us. it's not helping our children. >> i should say we had a long conversation with john walsh from the industry group that represents cell phone makers and maintain they are falling radiation guidelines enforced by our own government and defer to fcc who say that cell phones are safe and we tried several times to ask the fcc how can they be so sure cell phones are safe.

they wouldn't speak to us about this and referred us to their website which responds to the skeptics urging caution by saying "the fcc does not endorse the need for any of these practices." a real estate agent who used a cell phone all the time. many of us do. he thinks in his case it gave him a brain tumor and he's fighting back. we'll tell you his story next on "sgmd." ♪

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we "sgmd." i'm dr. sanjay gupta. our focus this week is cell phone safety. during our investigation we met allen marks, a successful businessman with a remarkable story. mark's life-changing battle with brain cancer led him on this unique journey that took him all the way to capitol hill doing something he never expected to do. for allen marks, being in the real estate business for 30 years has been a passion. >> i like building homes and seeing people move into them, happy. >> reporter: but three years ago his life changed. >> i had a seizure. i don't remember it. >> reporter: the cause of that seizure, a malignant brain tumor. surgeons were able to remove the cancer. but he says the recuperation was

challenging. >> took a long time. even now, i have some deficits and you try to find ways to overcome them. >> reporter: there's something else. marks feels responsible for his own cancer. >> i know what it is. it was my cell phone use. there's no way you could put something to your head for 20 years and not have it cause something. >> reporter: while there are some studies suggesting cell phones pose a health risk, many others do not. as a trade group representing cell phone manufacturers tells cnn -- numerous experts and government health and safety organizations around the world have reviewed the existing database of studies and ongoing research and concluded that rf products meeting established safety guidelines pose no known health risk. but still, there are many cell phone manufacturers that recommend that you do not put the phone next to your head. that is something marks and his family support. >> i still use my phone.

i usually use a speaker phone. or i use a headset. >> marks and his wife are urging lawmakers around the country to require manufacturers to put warnings directly on the phones. they believe having the safety information in the manual simply isn't enough. today marks is able to provide for his family again and is back on top in the real estate business. >> roll over or do you fight? i'm a fighter. >> now we can't say for sure whether alan marks' tumors were indeed caused by cell phones, but good luck to him and his family. congresswoman gabrielle giffords' doctotors took a bone substitute and placed it in her own native bone. look around the edges. these are little plates they put

in four little screws, two in the bone substitute, two in the native skull and affixed that to the skull, then they actually close skin over that giving a normal contour back to her head again. got another incredible story as well of recovery. a car hit rob somers, then drove off leaving him paralyzed from the chest down. had he some sensation in his legs but that was it, and that was five years ago. this week his doctors announced somers has been able to stand up, using a harness that helps him along. doctors re-established neuro connections by electronically stimulating rob's lower spinal cord. amazing story. we'll see what answers and solutions it leads to for other spinal cord injured victims. coming up, i'll answer your questions about cell phone safety. you've got a lot of them. interesting ones ahead. stick around. [ thunder rumbling ] [ thunder crashing ]

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we are back with "sgmd." as you know by now, we are talking about cell phone safety and apparently you have a lot of questions about this. i have to share this one. we've gotten this question many times over the years, about this viral video. i'll tell you right off the top, this is not real. this is a hoax. question was, can cell phones really pop popcorn. no, they can't. that's not the type of radiation we are talking about. while entertaining, just a hoax video. we have a lot of legitimate questions. this from our blog -- if cell

phones cause cancer, wouldn't we have seen a huge increase in brain cancer recently? very important question. again, the answer sort of is this idea that not necessarily because it takes a period of time for cancers to develop. cell phones have just become popular in this country over the last 15 years. there's only 30 million cell phones in this country in 1996 and now there are ten times as many, 300 million. people are using their cell phones more but it takes 0 to 30 years for these tumors to develop. we haven't had that time yet. this -- i'm a parent with a child who keeps her cell phone stuck to her head! what's the greatest risk for her? the greatest risk is you don't get to talk to your child as much anymore. children have thinner scalps and skulls and as a result radiation may penetrate more greatly. that's a concern, dr something dr. black brought up. there have been no studies so

far on children and cell phones. nothing in a peer review journal that we could look at. i found that alarming because children are using phones at an earlier age and are going to use them throughout their entire lives. cell phones can be extremely distracting. your child's sleep schedule may be changed. these phones can be just as stimulating as a television, like minicomputers. many children stay up late at night playing on their various phones, versus winding down. it can really throw that sleep schedule off. this one -- i text on my phone more often than talking. is radiation from texting the same as a phone call? here's the good news -- it is not. texting actually is a much safer alternative. the amount of radiation that you absorb goes off exponentially as you move the phone away from your ear. you could also use speaker phone and you could use a wired earpiece. i use mine all the time. it is a simple thing to do to mitigate your risk. not asking people to turn their