MR. KOJO NNAMDIFrom WAMU 88.5 at American University in Washington, welcome to "The Kojo Nnamdi Show," connecting your neighborhood with the world. Later in the broadcast, the science of snack foods, how one company is trying to engineer healthier foods. But first, in another round in the debate of cell phones and radiation risk, an international panel of experts organized by the World Health Organization has concluded that cell phones are possibly carcinogenic.

MR. KOJO NNAMDIThe report comes after the panel reviewed hundreds of studies on the subject. The panel stated that the evidence is not conclusive and more study is needed. But the report is sure to fuel the long standing debate between industry groups who reject these findings and health and environmental advocates. We'll explore what it means for your cell phone use. Joining us by phone from Oakland, Calif. is Renee Sharp.

MR. KOJO NNAMDIRenee is a senior scientist and head of the environmental working groups California office. Renee Sharp, thank you for joining us.

MS. RENEE SHARPHappy to be here.

NNAMDIJoining us by phone from London is Henry Scocroft. He is cancer research U.K.'s science information manager. Henry Scocroft, thank you for joining us.

MR. HENRY SCOCROFTIt's a pleasure.

NNAMDIHenry, I'll start with you. The World Health Organization now says they classify cell phones as possibly carcinogenic. What does that mean?

SCOCROFTWell, the first thing to say here is that this isn't based on any new evidence that's come out. This is an assessment by an international body to try and fit the radiation emitted by cell phones into their existing frame work for how we looked at and assess the cancerous from various things. And they concluded that there's not enough evidence to put into group one to group 2 A.

SCOCROFTSo they put it down in group 2 B, which is -- just to go through what 2 B says, it's possibly carcinogenic to humans. There's limited evidence that something causes cancer in people. But even evidence from animal studies is less than sufficient to rank it any higher. So this is really a source of (word?) category things where there's very shaky evidence.

SCOCROFTThis isn't -- there certainly isn't any new evidence or that mobile phones are being upgraded from a lower category or anything like that.

NNAMDIIs this like saying that hairspray possibly causes cancer? How seriously should we take this, Henry?

SCOCROFTIt's -- our advice to the public hasn't changed as a result of this. Given all the studies that have been done over the years, it's -- the U.K. government even says to take precautions on this, you should keep your calls short and people under 16 should only make essential calls. But that's really a precaution in the light of awaiting further evidence. And what do we make of this?

SCOCROFTI mean, is it like hairspray? I think, it's -- if you go and look at other things that you find in category 2 B of the IARC -- IARC classifications, you find things like pickled vegetables, coffee, carpentry and a range of things which really, I mean, aren't things that we would look at as the day to day risk for ourselves. And I think we should look at cell phones in the same way.

NNAMDIRenee Sharp, the environmental working group has been studying the issue of cell phone safety since 2009 and advocating that the scientific community ask hard questions about the effects of radiation. What do you take away from the WHO's conclusions yesterday?

SHARPWell, we think it's a very significant finding and really a game changer. It really echoes what we've been saying, which is not, okay, everyone freak out, cell phones cause cancer, but more, wow, you know, there really is accumulating evidence and there really is reason for concern. Certainly there's need for more research. I think everyone agrees with that. But really, this is the time when the consumer should be thinking about taking some precautionary measures.

SHARPYou know, really, when it comes to brain cancer, it's better safe than sorry. And I do want to mention that it's true that in the category that WHO ranked cell phone radiation, there are things like coffee and pickled vegetables. On the other hand, there are also things like lead and engine exhaust. So I think it's a mistake to dismiss the World Health Organization's findings because the category that they ranked cell phone radiation in is rather low.

SHARPI mean, the answer is you would be pretty shocked, actually, to see more evidence now, just given that brain cancer, for example, has a very long latency period. And cell phones just haven't been in wide use for a very long period of time. So I don't think that this question is really going to be answered for, you know, another decade or perhaps even more. But in the meantime, consumers should be aware and take some precautions.

NNAMDII'd like to ask our callers to join this conversation. It's 800-433-8850. Are you concerned about cell phones and radiation? Do you take any precautions when using a cell phone, using the speaker function or headphones? 800-433-8850 or go to our website, kojoshow.org, ask a question or make a comment there. Henry Scocroft, this is new for the World Health Organization. It previously said there was no increased risk from cell phone use. What has in fact changed?

SCOCROFTWell, I think, this is more -- again, nothing has changed here. What they've done is gone and looked to all the studies and concluded that, if you look at A, epidemiological studies have been done. The studies that have looked at lots of people. There's only a few that show an affect. And there's quite a few that show no affect. So on balance, you have to conclude that we don't know. But it's also worth mentioning that -- and I'd like to echo Elizabeth's (sic) comments on this.

SCOCROFTThere is a -- we don't know. Because there's a long way to go and cancer's can take a long time to develop. But set against that, if you go and look at the cancer rates that have been measured since, you know, 1985 onwards, when cell phones started being used, we haven't seen any change in the instance of brain cancer. It has been flat. The studies in the U.S., in New Zealand, in Denmark, in Norway, in Sweden and in Finland and here in the U.K, haven't seen any dramatic rise in brain tumor rates yet.

SCOCROFTSo I completely echo the sentiment that, you know, it's worth not, you know, spending hours and hours on the phone when we don't know, but the evidence that we have so far, doesn't suggest that it's going to come out one way or the other.

NNAMDIThe words, yet and so far, seem to be particularly significant, Henry. It seems like shifting cell phones from the possible carcinogen category to a more definitive one, won't be easy. What would be the next steps in studying this health risk?

SCOCROFTThere are some large -- one of the things to say about the evidence to date, is that, with the exception of one study, all of the studies that have been done, have been done asking people to remember how much they use cell phones in the past. There's only one study that's a study from Denmark which has actually followed people over the years. There are now several study -- there's certainly a large study in the U.K. called Cosmos, which is actually asking people to regularly update an online questionnaire about how they use their cell phones.

SCOCROFTAnd this will hopefully shed some more light on this. But, I think, only very long term detailed studies that follow people over a period of time rather than asking them to think back, will answer this question. And just to say, on that point, I mean, the potential bias' that can be introduced into a study from recall are significant especially when you're asking people with brain cancer to remember what side of their head they use their mobile phones on.

NNAMDIRenee Sharp, there was also a study in February reported in the journal of the American Medical Association, that showed increased brain activity when cell phones were used. How did that study affect the debate over cell phones and cancer?

SHARPWell, the study isn't directly linked because they didn't actually look at cancer. But it was a very significant finding for a couple of reasons. Number one, it was a study that was done by the U.S. federal government. And that's pretty significant in and of itself because the U.S. has really not been doing that much research into this question and certainly not a federal level. For example, there was a large -- very large in a major multi country city, in the inner front city in the U.S. did not take part in that.

SHARPSo that's number one. Number two was that they actually found, in fact, and they basically took people and they put two cell phones up to their ears and they didn't tell them which one they were going to turn on. They both had them on, but one actually had a call come in. And then they kind of changed it from day to day and people didn't know what's going on and they actually saw increased brain activity.

SHARPAnd the interesting things, they didn't actually see the heating of tissues. And that's important because there are a number of people, for example, in the cell phone industry who claim that the only potential effects from cell phones is related to heating of tissues and that certainly can't cause cancer. And I think that most scientists who believe that there may be a link between cell phones and cancer, think that it's not due to heating, it's due to some other mechanism that they actually don't know.

SHARPAnd this study, basically, kind of pointed to the possibility that that may be accruing because they didn't honestly know exactly what was going on or why that was causing that. Now, of course, we need more research in that. And the researcher who did that study, Dr. Volkow, is the first person to say that. She also advised precaution around cell phones due to just her own concern.

SHARPSo I think that's just another piece of the puzzle to say, hmm, wow, you know, I think that we should look at this harder, and I think that, you know, people should take some very basic precautionary measures just like, for example, texting instead of talking, using a headset, holding the phone away from their body. And I did want to respond to one point the other...

NNAMDIThat Henry made? Yes.

SHARP...guest made. Go ahead.

NNAMDINo. Go ahead, please. The...

SHARPJust very quickly.

NNAMDISure.

SHARPThe point about, well, we're not seeing any increase in brain cancer rates.

NNAMDIHe did say, yet.

SHARPWell, again, you wouldn't expect to because if you look at lung cancer and tobacco use, it took 40 years after tobacco use spiked to see overall increases in lung cancer mortality. So we're not going to see that sort of effect from many years to come.

NNAMDIOn to the telephone...

SCOCROFTI just (unintelligible) ...

NNAMDIGo ahead, please, Henry.

SCOCROFT...but say that Jonathan Summit, who is the chair of the online group did, you know, in the report, he says, the conclusions mean that there could be some risk and we need to keep a close watch for a link. But he...

SHARPRight.

SCOCROFT...but that, by his own admission, that doesn't mean there's a link yet. We haven't seen anything either way.

NNAMDIHere is Pat in...

SHARPAgreed.

NNAMDI...Sterling, Va. Pat, you're on the air. Go ahead, please.

PATHey, Kojo, I think, there may be a link. My father passed away from brain cancer and just before he passed away, they were able to show him the cluster of tumors on an x-ray or CAT scan, whatever it was. And he made a remark that that's just where the sonar earpiece used to sit when he was in the Navy, pinging sonar. So I think there may be some association, it may be more so magnetic than microwave or it may be a combination of both. But I just wanted to add that for thought.

NNAMDIPat, thank you very much for your call. I also want to add Kevin in Falls Church, Va. Kevin, you're on the air. Go ahead, please.

KEVINThank you, Kojo. My brother died 10 years ago from brain cancer in Germany. And his doctors point blank told us, it's was from excessive use of his cell phone. Especially the nature of the brain cancer was so aggressive that they really (unintelligible) diagnosis, but what it was and it happens to cell phone radiation.

NNAMDIWell...

KEVIN(unintelligible) ...

NNAMDI...Henry Scocroft, how could a doctor, 10 years ago, say definitively that Kevin's brother's brain cancer was the result of use of a cell phone?

SCOCROFTI honestly can't comment on that. I mean, that's mystifying. And because as we've talked about already, there just isn't really the evidence from what we know to make that kind of statement. I mean, I wouldn’t want to say anything more than that. I'm afraid that's quite strange.

NNAMDIRenee Sharp, care to comment?

SHARPI would kind of agree. I'm skeptical of such claims of people saying this is clearly caused by this because, I mean, I think that's a very hard thing to figure out. But, you know, I can understand, you know, people's real concerns because he's certainly -- I certainly talk to a number of people who have said, you know, my husband has had a brain tumor, we think it was caused by cell phones.

SHARPWe went around the cancer ward and basically asked people, you know, if you have a brain tumor, what side is it on and what side did you hold the phone on and, you know, there was, you know, quite a bit of correlation. Again, that's not proof. That's just, like, another reason to say, wow, you know, we need to look at this further.

NNAMDIHenry, Europe has been looking into the health risks of cell phones for a long time. What recommendations have there been regarding cell phone use in the U.K. and Europe?

SCOCROFTWell, as I mentioned, that of the U.K. government's precautionary recommendations are that people should keep their calls short actually and for people -- for the under 16 to only make essential calls rather than, you know, chatting for hours.

SCOCROFTThat's essentially where the recommendations are at, you know, and that has all been very much based on precautionary principle rather than on hard evidence. Because as we've talked about, there's very limited -- certainly, you know, we've talked about the fact that mobile phones can -- have been shown to change brain patterns in one side of the head. But that's very different from the sort of detailed evidence that we have from the chemicals in tobacco smoke, which you can see, you know, you can see the damaging DNA.

NNAMDIRenee, many studies have shown that children absorb much more radiation than adults. Why is that?

SHARPFor several reasons. One reason is that their skulls are thinner. Another reason is just their head shape. Actually, radiation kind of just penetrates further and also their tissues are somewhat different. And some of those major findings were actually found interestingly by the French Telecom industry itself.

SHARPAnd this may be one reason why France is actually taken some pretty significant measures to limit cell phone advertising to children and cell phone use in elementary schools, for example.

NNAMDIWell, we have one final call. Here's Susan in Arlington, Va. Susan, you're on the air. Go ahead, please.

SUSANHi, thank you Kojo. So my question might seem a little bit silly, but I think it is a legitimate concern. I, like many women, tend to carry my cell phone in brassiere and I'm wondering if this same exposure to radiation is occurring while the phone is not actually being talked or used, but is receiving signals. And is that exposing my breast tissue to unusual amounts of radiation?

NNAMDII'm uncomfortable. Renee, that question makes me uncomfortable. Would you care to answer it, please?

SHARPWell, it sort of depends on your phone. If you have a Smartphone, for example, if you have your cell phone, then information is being pushed onto it. So, yes, you are being exposed to, you know, some radiation. Less, though, than if you are, say, for an example, actually making a call.

SHARPBut that is one suggestion that we make is if people are concerned, you know, carrying it in your pocket or directly next to your body is not recommended. I think it's also notable to point out that if you actually read your cell phone manual, I think it will actually say that if you are putting your cell phone next to your body, you're actually -- not your head, but your actual, you know, soft tissues, you're actually exceeding the FCC's exposure guidelines.

NNAMDISusan, thank you very much for your call.

SCOCROFTCould I just add one point to that, though? The IARC recommendations specifically refer to two types of brain tumors, Gliomas and Acoustic Neuromas and they've said it's completely inadequate when it comes to other types of cancer. So even this sort of very limited assessment by IARC doesn't suggest there's any link to breast cancer, whatsoever, at this stage.

SHARPAnd I would agree with that. I would just, you know, again, it's not that hard to make a few changes to take some precautions. So we're not saying, wow, yes, there is definitely a link, but, you know, why not? It's not that hard and it might protect you from cancer down the line, maybe and that's worth it.

NNAMDIJust about out of time. Susan, thank you very much for your call. Renee Sharp is a senior scientist and head of the Environmental Working Groups California office. Renee, thank you for joining us.

SHARPThank you.

NNAMDIHenry Scocroft is Cancer Research U.K. Science Information Manager. Henry, thank you for joining us.

SCOCROFTIt's been a pleasure. Thank you very much.

NNAMDIWe're going to take a short break. When we come back, the science of snack foods, how one company is trying to engineer healthier foods. I'm Kojo Nnamdi.