BROOKE GLADSTONE: This week, the World Health Organization released its long-awaited Interphone meta-study into the link between cellphones and brain cancer. Ten years and 24 million dollars later, it couldn't find a link, only the vague suggestion of a link – very unsatisfying, not just because it was inconclusive but, because cellphone technology and usage has radically changed since that data was collected, it’s probably irrelevant. We'll report this as an object lesson in how hard science can be to report. But be forewarned – you won't be satisfied either. Dr. Daniel Krewski is one of the authors of the Interphone Study.

DANIEL KREWSKI: Overall, the study did not show any clear evidence of an increased risk of either glioma or meningioma. These are the two main types of brain cancer. But in the highest user group for cellphones in the Interphone Study - that’s the top 10 percent of cellphone users who use the phone for more than 1640 hours cumulatively - we did see a suggestion of an increased risk of glioma, an odds ratio of 1.4, which means a 40 percent increase relative to the background glioma rate.

BROOKE GLADSTONE: Aren't you burying the lead there, that there appeared to be, from your study, a 40 percent increase in risk if you logged beyond a certain number of hours of cellphone use?

DANIEL KREWSKI: That’s what the data would suggest at face value, but if you looked at all of the other exposure categories that we had, there was actually no evidence whatsoever of an increase in risk.

BROOKE GLADSTONE: I don't understand.

DANIEL KREWSKI: Well, it’s just in the highest category of utilization that there was a possible association. There was some concern that the reporting accuracy in that group may not have been perfect. And we also have some questions getting at some of the weakness of the study with recall bias and selection bias, some of which we can correct for, some of which we cannot.

BROOKE GLADSTONE: In other words, some people may not remember how much they actually used their cell phone.

DANIEL KREWSKI: That’s correct. The group did look carefully at that highest decile of cellphone use, noticed that there was a significant increase and did draw attention to that. But considering the limitations of the data, we're not willing to conclude that that was a causal relationship.

BROOKE GLADSTONE: You’re accepting the correlation but discounting the causal relationship?

DANIEL KREWSKI: We are taking that as a suggestive correlation that needs to be followed up in the future. We do require continued vigilance with this technology because we haven't unambiguously answered the question. It’s a little embarrassing as a scientist to say we've spent ten years and 25 million dollars and we're not absolutely sure what’s going on. But there are limits of science, and we were pushing the limits of science with this large-scale investigation.

BROOKE GLADSTONE: One criticism is that the amount of phone use was so much smaller back then.

DANIEL KREWSKI: It does apply to the conditions of use that were in place at the time the Interphone Study was designed and executed. If you look at our top 10 percent of cellphone users, those individuals who use the phone for more than 1640 hours cumulatively, that averages out over a ten-year period to only a half hour a day, which would be considered perhaps not heavy use by today’s standards.

BROOKE GLADSTONE: I guess that’s the problem. Phones were different back then. Have you produced news we can't use?

DANIEL KREWSKI: Once you start down that road of designing a study to go into the field in the year 2000, you’re basically working under conditions that were in place at that time. I think we should take some comfort in the fact that we've done the largest study by far ever conducted on a population basis in 13 countries of cellphone use and cancer risk. Overall we see no risk. I think that should be comforting from the public health point of view. At the same time, the hints of association in the high-dose group from Interphone and some similar hints from other studies, I think those suggestions need to be followed up, and I think further research in this area is warranted.

BROOKE GLADSTONE: Dr. Krewski, thank you very much.

DANIEL KREWSKI: Thanks.

BROOKE GLADSTONE: Dr. Daniel Krewski is one of the authors of the Interphone Study. One area in particular he says needs more research is the effect of cellphones on children. No young people were included in the Interphone Study, and this is just one of the many complaints Dr. Devra Davis has with it. She says this meta-study also excluded data from more recent studies that looked at more frequent mobile phone users and which do suggest harmful effects from cellphone use. She says concerns about the dangers of cellphones can actually be found in the fine print of your cellphone manual.

DEVRA DAVIS: BlackBerry, for example, will tell you to hold the BlackBerry .98 inches from the body. T-Mobile says leave it .98 inches. The iPhone, it says at least 15 millimeters (5/8ths of an inch) away from the body. I surmise that they did this because they understood that if you held the phone directly on the body, you would be exceeding the recommended specific absorption ratio. That’s the SAR. And those had been set in concert with recommendations of the FDA and the FCC, but those original SAR calculations were established in 1993 based on the head of a six-foot-tall man who weighed 200 pounds having a head that weighed about 11 pounds. Most of the people using cellphones around the world today do not have 11-pound heads. More than half of them are very young.

BROOKE GLADSTONE: The kind of radiation that comes from a phone is non-ionizing radiation - that is to say, an electron isn't removed, making an unstable situation. It’s merely exciting the atoms, right?

DEVRA DAVIS: Well, that's right. And we used to think that it was completely innocuous at these very low powers. I certainly thought that for years when I had two or three cellphones. But, in fact, more recent research that’s been done in Sweden, in Japan, in Israel, in Finland, has shown that non-ionizing radiation at very, very low power but with the digital pulsed signal that you get with today’s smart phones, that radiation has profound biological effects.

BROOKE GLADSTONE: Do you get accused of being a conspiracy theorist, of being part of the, you know, aluminum foil hat brigade?

DEVRA DAVIS: Oh, oh, gosh, no, because, you see, at this point there are very respected scientists at the leading institutions. I mean, does the Finnish Nuclear Radiation Agency sound like a lunatic group?

BROOKE GLADSTONE: [LAUGHS] Some people are shrugging in the control room.

[LAUGHTER]

DEVRA DAVIS: Well, all right. Take a look and see. They advised, most recently in January of this year, that there should be simple precautions in using cellphones.

BROOKE GLADSTONE: What would a study have to find for you to be convinced that cellphones are safe?

DEVRA DAVIS: We would need 30 more years to see no excess risk of brain cancer. That’s what we need. The Europeans are going to do exactly that, a 30-year study, and that study is going to follow people carefully and see what their cellphone habits are. And at the end of that study, you'll have an answer.

BROOKE GLADSTONE: Well, except the phones will continue to change, so you’re going to run into the same problems in the next 30 years at least 100 times worse than they were in the last 10.

DEVRA DAVIS: You know, you’re raising questions I really can't answer for you. But I can tell you this. I would like the government to use some of the funds that they collect every month for cellphones to fund independent research. Why did the United States of America not participate in the world’s largest study of brain cancer and cellphones? Is it because the question is totally resolved? I don't think so.

BROOKE GLADSTONE: Thank you very much.

DEVRA DAVIS: Well, thank you.

BROOKE GLADSTONE: Dr. Devra Davis is the author of Disconnect, due out in September, and the founder of the Environmental Health Trust. James Geary wrote about the health consequences of cellphones earlier this year in Popular Science Magazine. Months ago, he predicted that this study would indeed solve nothing. James, welcome to the show.

JAMES GEARY: Thank you very much.

BROOKE GLADSTONE: So let's look at some of the headlines – no conclusive link between mobile phones and cancer, study shows more research is needed, study shows small increase in brain cancer.

JAMES GEARY: [LAUGHS] Well, unfortunately, all those headlines are true and, equally unfortunately, all those headlines are incomplete.

BROOKE GLADSTONE: But, let's face, it the study isn't helping the situation very much.

JAMES GEARY: [LAUGHS]

BROOKE GLADSTONE: Part of the problem is trying to prove a negative. If a study doesn't find a clear connection, that could mean that there is, in fact, no connection, or it could mean that the study wasn't conducted very well or wasn't looking for the right thing or wasn't big enough.

JAMES GEARY: Yeah, I think you’re right. If you read the Interphone paper itself, probably half, if not two-thirds, of the paper was an explanation of why these results are unreliable rather than what the results actually were. But that’s not due to incompetence on the part of the researchers. It has to do with the fact that the study itself was initiated more than ten years ago and so the technology was different and the people using it were different.

BROOKE GLADSTONE: I know the industry paid in part for the Interphone Study, and I wonder how big was the industry’s role in crafting the message either of the study or around the study.

JAMES GEARY: There are many people who, you know, believe there is a vast conspiracy to cover up the scientific research that suggests there is a risk from cellphone radiation, and the main culprits behind that alleged cover-up are obviously the cellphone makers themselves. And having spoken with cellphone manufacturers, many, if not all of them, fund these studies through a sort of blind trust. They give money to an organization and that organization then funds studies without any kind of input or knowledge of the cellphone makers. I mean, obviously that doesn't mean there is no influence.

BROOKE GLADSTONE: What about a PR effort, like the junk science organizations that were created by the tobacco industry?

JAMES GEARY: Well, there’s obviously a huge PR effort going on. But the fact is that most of the studies are on their side. Most studies suggest there is not a correlation. The scientists whom I interviewed who did believe there could be a risk, none of them said cellphones cause brain cancer; they don't believe that. What they did suggest was that there could be mechanisms that we don't understand whereby cellphone radiation could sort of damage the immune system or cause DNA breaks that could lead to a weakened immune system; that that, combined with other environmental factors, could have a cumulative effect. And that is what we should be studying, and not looking at a very, very small subset of that question, do cellphones cause brain cancer, because most of the evidence suggests that they do not. But there are enough indications and enough respectable, reliable studies to suggest that there could be something going on, and that, in my opinion, needs to be explained in a way that does not exaggerate the risk or the safety of what’s going on.

BROOKE GLADSTONE: Where do you wear your cellphone?

JAMES GEARY: I don't carry it on my body. I use it maybe two or three times a day, and probably half the time I'm texting rather than talking. I think they're very useful and fun devices. But exactly because they're so useful and so ubiquitous, I think we really need to do the research and find out what’s going on with them, if anything.

BROOKE GLADSTONE: James, thank you very much.

JAMES GEARY: Thank you.

BROOKE GLADSTONE: James Geary is an author and contributor to Popular Science Magazine.

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