Web edition: May 25, 2011
Because the reader letters we get here at Science News can be among the most provocative and insightful parts of the magazine, I make a point of checking out the correspondence pages of scientific journals for equally juicy material. In the Letters section of the May 25 Journal of the American Medical Association, I hit paydirt in the form of an electrifying debate over a paper published in February that claimed to find evidence linking cell phone radiation to increased brain activity (SN: 3/26/11, p. 13).
Physicists, engineers and a brain expert aired their grievances in three letters, raising objections over the study’s methods and conclusions: The physics of cell phone radiation was oversimplified. The researchers weren’t blinded to the phone conditions. Claims made in the text didn’t jibe with the “representative” brain image.
And don’t even get them started on heat. Two independent groups wrote that thermal effects from the active phone could have caused the purported brain activity boost, without having to bring cell phone radiation into the equation.
The nice thing about letters pages is that, usually, the author gets to respond. Here, the researchers behind the original work, led by Nora Volkow of the National Institute on Drug Abuse in Bethesda, Md., defended their study, answering objections point by point. (The radiation model used was just fine, thankyouverymuch. Statistical software determined the important brain regions, so the researchers didn’t need to be blinded. The representative brain image was, in fact, showing what the study claimed.)
And as for the thermal effects, the researchers argue that if heat — and not cell phone radiation — were behind the brain activity increase, then they would have seen a boost in the brain region closest to the cell phone’s hot battery. (They didn’t.) They also would have seen brain activity shoot up in the area that handles temperature detection. (It didn’t.) What’s more, simulations predicted that a brain temperature increase from an active cell phone would be around 0.1 degrees Celsius, which is generally considered too small to have an effect.
Read the full exchange, and you’ll see that it’s not obvious who is right and who is wrong. The only clear thing is that it will take more experiments, both by the same group and by others replicating the work, to sort out what’s really going on. And there’s lots more work to do. After all, as reported in the original story on the study, even if we all agree that cell phone radiation does change brain activity, no one knows what that change means.
Letters. JAMA. Vol 305, No. 20, May 25, 2011, p. 2066-2068. Available online: [Go to]
Volkow et al. Effects of Cell Phone Radiofrequency Signal Exposure on Brain Glucose Metabolism. Journal of the American Medical Association. Vol. 305, February 23, 2011. Available online: [Go to]
L.Sanders. Cell Phones May Affect Brain Metabolism. Science News, Vol. 179, February 22, 2011, p. 13. Available online: [Go to]