vital news to anyone who uses a cell phone. today, world health organization panel took a fresh look at the medical research and concluded that cell phones are possibly carcinogenic. days after dr. sanjay gupta investigated serious questions about the current research on cell phones and cancer. here's a portion of sanjay's report, which aired as recently as last night, foreshadowing today's stunning 180 from the w.h.o. on cell phone safety. >> 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 cell phone use is safe. i think that the public has a right to know that there could be a potential risk. the public generally assumes 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 in cancer. their conclusion, little or no evidence cell phones are associated with brain tumors. but 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 brain glioma, a type of tumor. >> that's what triggered today's warning, a closer look at the studies. last year, interphone, a 13-country study, found no overall higher risk of brain tumors but found that people who used a cell phone for ten years or more had double the rate of a cancer called glioma, which is one of the most aggressive forms of brain cancer. other studies have been more reassuring. some studies have caused new reasons for concern. earlier this year, researchers using brain scans showed that less than an hour of cell phone use can increase brain activity in the area closest to the phone antenna. it's important to point out, cell phone radiation is measured on the assumption that you do not hold the phone to your ear. but who does it that way? phone makers recommend half inch or more. for years, i like most of you, pressed the phone against my ear. even the manufacturers recommend that you don't do that. the studies are confusing and none is done the same way. and then there's this, our medical producer spoke recently to a researcher, dr. henry lay of the university of washington. like the w.h.o., he's been reviewing cell phone studies. what he found is that in the studies not funded by the cell phone industry, 67% reported negative health effects like fertility problems and cancer. but in a studies that were funded by the cell phone industry, just 28%. again, that's according to a respected long-time researcher on radiation and its effects on people. but just like anything to do with the cancer link, you can't draw any firm conclusions on that, just like the w.h.o. couldn't draw a firm cancer connection from the studies they looked at. they could only confer possibilities and reasons for concern. that's why the cell phone industry trade group say the reports say they do not cause cancer, but they do say they might. i sat down earlier tonight with dr. sanjay gupta. the world health organization has always assured consumers that cell phone radiation had no adverse health effects. today it seems like a different message that they're sending. >> it very much does. this is happening as what he speak. what they're saying is that cell phone use and these electromagnetic waves, they're going to classify that as a possible carcinogen. carcinogen means cancer causing agent. so this is very different from what we've been hearing from the world health organization for some time. look, this is 31 scientists representing many different countries. they looked at existing studies, anderson. many of the ones we've talked about. this wasn't new research. they looked at the existing studies, including the interphone studies and after deliberation, they came to this conclusion, a possible cancer causing agent is how they're labeling it. >> what is a carcinogen? other carcinogens are lead and chloroform, but the cell phone industry is dismissing this, saying coffee is also listed in this group. >> the way that they classify these things, they say there's things like tobacco, there are things that are probable carcinogens and this they're calling a possible carcinogen. and you're lead -- you're right, lead and chloroform is in that category. gasoline exhaust is in this category. with regard to coffey, i saw that, as well. coffee, there was some concern that there might be an increase in bladder cancer as a result of coffee consumption. but you're getting an idea of the imperfections of the science here. they can draw a cause and effect relationship. they're not saying they have done that by any means. looking at all the existing studies, they're changing their stance. the world health organization is changing their stance and saying this is not something that we're going to say has no merit whatsoever, we're saying this is a possible carcinogen and merits more study. >> so the u.s. government is also very firm in saying there's insufficient evidence that cell phone radiation poses a health risk. do you think the w.h.o. decision may now alter the u.s. policy? >> i think they might. we talk about the fact that the fcc says look, there's no risk, you don't need to do anything extra to protect yourself, which we reported on a couple weeks ago. you know, the world health organization is a very legitimate body of scientists. again, they represent scientists from all over the world. they all have a lot of legitimacy, so i think it will be interesting to see how they react. they're not saying a cause and effect relationship, but they're saying that there's no evidence whatsoever, we're not saying that either. so this is a step in another direction for them. >> it sounds like the bottom line here today is something you've been reporting on this program for several weeks is cell phone radiation may cause cancer. so what are the best ways to limit exposure? >> that's the interesting thing about this. so many things we talk about on that list that you mention, they're more unavoidable. there aren't many things that you can do to mitigate your risk. with this, even in the pamphlets that come with cell phones, they say you should not hold a cell phone next to your ear. they say you should be at least half inch to an inch away. you could use an ear piece is what i use. i think that by simply doing that, the amount of radiation drops off significantly the further and further away it is from your head. we're talking about the brain here. the glioma, this is what they're most concerned with here. move that cell phone away from your ear, use an ear piece like this and you can greatly mitigate your risk. >> i think that's important. when you told me that when we did this story a week or two ago, i bought an ear piece and i've been using it since. or i've been trying to text a lot and keeping the phone away from my body and not in my pocket. but i don't think most people know that. everybody you see on the street, they have the phone pressed up against their head and that's how i've been using it for years. >> most people do. and i think that what is so interesting about this, anderson, we're seeing this unfold real time. we talked about this a couple times over the last couple weeks. this world health organization, i don't think anybody knew what they were going to say before we heard the announcement this afternoon. this is unfolding. as more people learn about this, the message is absolutely not saying don't use your cell phone. people are going to use their cell phone. the message is there's a possibility of a risk here and it's an easy one to address. most people can address this pretty easily. especially children who will likely be using a cell phone for the rest of their lives, should think about this, as well. >> and studies have not been done on the effects of children, right? >> there have not, which i think is surprising. a lot of the concern is that the skin is thinner, the bone is thinner. could the effect be greater as a result? >> get an earphone if you can. use that, keep the cell phone away from your body and away from your ear, even if you don't have an ear piece, just keep it away. sanjay, thank you very much. >> you got it, anderson. >> let us know what you think about it on facebook or twitter @ anderson cooper. i'll be tweeting some tonight. still ahead, we've seen a lot about syria, but this is perhaps the worst. a 13-year-old boy reportedly tortured and murdered by the regime. his name, hamza. his death has sparked renewed outrage in syria. i know it's hard to take, but we feel we owe it to this little boy to bear witness to what has happened to him. we'll talk with a human rights activist hiding in syria right now. also, the revealing photographs from congressman anthony wiener's cell phone. he said he was hacked but he's refusing to answer more questions and he had a very heated exchange. we'll show you all of it but here's just a short part. >> we follow some rules here and -- >> i would love to get an answer. >> you do the question, i do the answer and this jackass interrupts me? >> he's talking about our producer. isha sesay is following other stories for us tonight. isha? a dramatic day in the casey anthony trial. cindy anthony, casey's mom, bloke down on the stand and she practically collapsed. she had to ask the judge for a break. coming up, the 911 recording that made her fall apart. tonight, the question k, building up our wireless network all across america. we're adding new cell sites... increasing network capacity, and investing billions of dollars to improve your wireless network experience. from a single phone call to the most advanced data download, we're covering more people in more places than ever before in an effort to give you the best network possible. at&t. rethink possible. constipated? phillips' caplets use magnesium, an ingredient that works more naturally with your colon than stimulant laxatives, for effective relief of constipation without cramps. thanks. [ professor ] good morning students. today, we're gonna... [ woman speaking chinese ] thank you. do you have an english menu? no english. [ speaking chinese ] [ gasps, speaks chinese ] do you guys like dumplings? i love dumplings. working with a partner you can trust is always a good decision. massmutual -- let our financial professionals help you reach your goals. tonight, the question congressman anthony wiener is refusing to answer about a lewd photograph sent from his twitter account to a 21-year-old college student. andrew brightbart broke the story. and the next day wiener's office released this statement saying he had been hacked. over the weekend, he tweeted this -- >> the new york congressman seemed to be making light of the situation but has now hired a lawyer. his office said -- to brick you up to speed on 2 details, the college student the tweet was addressed to was jeanette who in the past tweeted this -- in a statement, she admitted she's a fan of the congressman and said he began following her on twitter a month or so ago. but as for her being her boyfriend, not so much. according to her statement, which also said, i've never met congressman wiener, though i am a fan. i am not his girlfriend nor am i the wife, girlfriend or mistress of barack obama, ray allen or cristiano rinaldo. so she says she wasn't being literal. but you can understand why reporters would want answers from the congressman himself. listen to this. >> you say that you were hacked, which is potentially a crime. why haven't you asked the capitol police for any law enforcement to investigate? >> look, this was a prank that i've now been talking about for a couple of days. i'm not going to allow it to decide what i talk about for the next week or two weeks. and so i'm not going to be giving anything more about that today. i think i've been responsive. >> but with respect, you're here, which we appreciate, but you're not answering the questions. can you just say why you haven't asked law enforcement to investigate? >> you know, dana, if i was giving a speech to 45,000 people and someone in the back of the room threw a pie or yelled out an insult, would i spend the next two hours responding to that? >> no. >> i would get back -- >> this is not that situation. >> you want to do the briefing? do you want to do the briefing, sir? >> from your twitter account, a lewd photograph was sent to a college student. answer the question, was it from you or not? >> do you want me to finish my answer? >> yes, this answer. did you send it or not? >> if i were giving a speech to 45,000 people and someone in the back threw a pie or yelled out an insult, i would not spend the next two hours of my speech responding to that pie or that insult. i would return to the things that i want to talk about to the audience that i -- >> all you have to do is say "no." >> that is what i intend to do. >> all you have to do is say no to the question. >> let me try a different question. >> the woman who allegedly got this tweet, this 21-year-old college student in seattle, she released a statement saying you follow her on twitter. is that true? and if so, what is the reason? >> you know, i have said this a couple of ways and i'll say it again. i'm not going to permit myself to be distracted by this issue any longer. >> all you have to do is say no to that question. if you're not following her on twitter -- >> why don't you let me do the answers and you do the questions. >> congressman, you understand the frustration. we appreciate you're talking to us, you're smiling, you're cooperating, but you're not answering the question. >> this is now day three. you have statements that my office has put out. >> but they don't answer the question. >> there are statements that i've had my office put out and there are going to be people who -- look, this is the tactic. the guy in the back of the room who is yelling out the insult wants that to be the conversation. >> but you said you were hacked and that's a potential crime. >> dana, i'm going to have to ask that we follow some rules. one of them is you ask the question and i'll give an answer. >> i would love to get an answer. >> you do the questions, i do the answers and this jackass interrupts me, how about that? let me just give you the answer. the objective of the person who is doing mischief is to try to distract me from what i'm doing. for the last couple of days that has happened. i made a decision i'm not going to let it happen today or tomorrow. >> if this is the nonstory you say it is -- >> i characterize it as a distraction. i'll leave it to you to make the distinction. >> if this is the distraction, you're a sophisticated guy, just answer the questions. >> i've been doing that for several days. now i choose -- now i choose -- there are people here who haven't read the statements. i assume that you have. look, all i can tell you is this, this is akin to someone deciding on day three or four they want to continue talking about something i consider a distraction and the decision i've made is i'm not going to permit it to distract me. i'm not going to permit it to continue on for three, four, five, six days. if that's unsatisfactory to you, i apologize. but i think what people want me to talk about is the debt limit vote tonight, or things like the oppressive disparity between the wealthy in this country and people that don't have as much or it's more difficult being in the middle class in this country. that's what i'm here to work on. thank you, guys. >> dana bash you saw in that interview joins me now with senior legal analyst jeffrey toobin. dana, what questions has he not answered? >> all the ones you just heard me asking. what is so weird about this is it's so plausible that his twitter account was hacked, it really is. the experts we talked to, it's very easy to do. so the fact that he just won't answer some basic questions just even say point blank that it wasn't him is very weird. >> so he has not said that's not a picture of my private parts? >> no. earlier today he came out and was very gracious and answered reporters questions earlier in the day, as well. he was asked, is the picture you? and he gave a similar answer to the one he gave over and over in the clip you just saw. >> and he wouldn't say whether he was following her on twitter, right? >> no, she -- the woman we're talking about, this 21-year-old college student, who was the alleged recipient of this tweet, she actually said in her statement to the "new york daily news" that anthony wiener was following her on twitter. so that's one of the questions you heard us try to ask, is that true, and if so, why were you following her? who knows? maybe she sent some funny tweets. he wouldn't answer that question. he kept talking about the 45,000 people in the room. >> jeff, why would he secure an attorney -- i get why he would secure an attorney but why wouldn't he contact the capitol police if in fact this was a hack? >> i can understand that. he might be hiring an attorney to see if he wants to sue someone. it doesn't mean he did anything wrong that he hired an attorney. the weird thing about this story is he started out being very open and treating it as a joke, and now in this sort of hilarious interview with dana and ted, he's acting like a perp, like someone who has something to hide, which of course extends the story and suggests he had something to hide. in his defense, we do need to point out that the person behind this is andrew brightbart, who's made a practice of targeting democrats, shirley sherrod most notoriously, and his stories tend to fall apart on close inspection. here, unfortunately or fortunately, depending on your perspective, wiener doesn't seem to be ending the story, he seems to be extending it. >> dana, if he called the capitol police and asked them to look into it, they would do that, right? >> absolutely. that is the protocol here on capitol hill. i talked to law enforcement sources, and they said that if -- it would not be unusual for a member of congress who felt that their account was hacked if they called the capitol police to please look into this, i want to know who did this, they would do it. and a spokesman for the fbi, who would also be a potential place that would investigate, they also said that congressman wiener has not called to ask for an investigation. which is as you saw, if you said you were hacked, why not get to the bottom of who did it? he said that it was a prank and wants to move on. but it was just a little odd that he wouldn't answer that question. >> it's also far from clear that even if he was hacked, there was a crime committed here. as far as i'm aware, there's never been a criminal prosecution based on impersonating someone on twitter. if he actually sent this lewd photo, i don't think that's a crime either. it's probably bad taste, but i just don't think this is really a law enforcement matter. it's a political matter. >> you get the sense that his strategy is just kind of wait this out and thinking it will just go away? >> absolutely. that's what it seems to be. he's very cognizant as i said of the optics of this story. earlier today, he came out to the cameras, talked to another one of our producers and was answering some questions and she started to ask another followup question. he came back and he said, i want to come back because i don't want you to have a shot of me walking away from the camera. today, he came over to us and to other reporters very carefully doing so, he even went to his office to put on a tie. he doesn't want to look like he's running away from this, he's coming and talking to us, it's just what he's saying is not answering basic questions about what all went down a