Monday, February 28, 2011

Do Cell Phones Make Your Brain Hungry?

People are often afraid of things they don’t understand. The way cell phones work is a mystery to most people, if by “mystery” we mean something that we may understand on a basic level, but something that has indefinite levels of complexity that we do not comprehend. By that definition, most pieces of electronic gear are mysteries even to their designers, because no one person any longer has an exhaustive understanding of all the pieces that go into a cell phone: the microprocessors, the RF circuits, the digital signal processing, the details of the semiconductor fabrication design, etc. Each designer knows his or her little bit, but no one any longer understands the whole thing exhaustively.

And the mysteries of cell phones pale when compared to the mysteries of the brain. Though we have just begun to be able to measure certain things about the brain, such as how much glucose it metabolizes where, this is just like studying an advanced computer based on how much power different parts of it consume, without being able to measure the actual signals inside. In either case, you could make some broad generalizations and correlations, but detailed understanding would be beyond your grasp.

So it’s not surprising that a recent article in the Journal of the American Medical Association (JAMA) showing a relationship between cell-phone use and brain metabolism got a lot of attention. The interaction between cell phones and the brain has got to be one of the most thoroughly studied matters in the history of medical science and electrical engineering. As cell phone use grew in the 1980s and 1990s, both industry and government labs studied nearly every possible way that the radio-frequency emissions from cell phones could affect the brain. No one denies that the watt-level or less power emitted from a cell phone causes a very slight warming of tissue. So does sitting out in the sun, for that matter. But if you dig down into the worst fears of the average member of the cell-phone-using public, you might find something like this: twenty years down the road, large numbers of people who have used cell phones extensively will all come down with some horrible incurable form of brain cancer and die lingering, mentally incapacitated deaths, all because they wouldn’t put down the durn phone.

The actual finding, by members of the National Institutes on Drug Abuse and Brookhaven National Laboratory, was a lot less serious than that. In the normal course of business, the brain metabolizes glucose from the blood to obtain energy for its operations. This is how the brain eats, so to speak. Positron-emission tomography (PET) combined with a special type of glucose-containing chemical allows brain scientists to measure the energy consumption, as it were, of different parts of the brain in real time. When they put cell phones next to both ears of 47 healthy test subjects for 50 minutes and turned one on (presumably they didn’t tell the subjects which one was on and which one wasn’t), they found that the parts of the brain closest to the phone antenna used 35.7 micromoles of glucose per minute per 100 grams of brain tissue. The other side used 33.3 micromoles. In other words, the side of the brain nearest the phone used about 7% more glucose than the other side. They are quite confident about the statistics of this result, but say that their finding is “of unknown clinical significance.”

My own uninformed guess is that the slight heating effect of the absorbed RF waves affected the brain’s sensitive temperature-regulating mechanism, and possibly increased blood circulation in that area as a result, producing more glucose use as a side effect. Obviously, more research is required, at a minimum another study showing that this effect is repeatable. Until that is done, the scientifically responsible thing to do is to suspend judgment, not get into a panic about using cell phones.

As I have said in other contexts, engineers should not ignore the public perception that cell phone use might damage your brain in some way. It’s something the industry must deal with, and is as real as consumer attitudes about price, color, service features, or anything else to do with a product. A report by Kent German on CNET stated that the Cellular Telecommunications Industry Association played up the “unknown clinical significance” aspect of the JAMA report, which is understandable. They could hardly be expected to embrace it with open arms. But as they point out, this is not the first time researchers have investigated the relationship between cell-phone use and brain activity. This study is unusual in that a definite statistical correlation was found, but whether the change in metabolism is harmful is just not known at this time. And the fact that this almost inconsequential finding has received so much publicity has to do with our attitude toward science as the ultimate authority in more and more aspects of life.

Every age has authority figures to which it looks for guidance. In the Middle Ages it was the Church, by and large. Since the nineteenth century, science has largely replaced other authorities as the recognized way of resolving questions of wider and wider significance, whether or not it makes sense to approach a problem in a scientific way, meaning armed with statistical studies and correlation calculations.

It’s hard to bear in mind that not all of life is best approached in that way. I rarely carry a cell phone, and turn it on even less often than I carry it. This is most assuredly not because I’m afraid of the RF radiation it emits. As an amateur-radio operator in my younger days, I got exposed to way more RF than most cell-phone users will take in from cell phones in their lifetimes. Once I even got burned—literally—on my thumb when I was working on an antenna, and a fellow amateur didn’t check my location before he keyed the transmitter. I am happy to report that the small scar healed in a week or so and my thumb has survived intact to this day.

I simply prefer to live my life without the added annoyance of having some telemarketer interrupt my already precarious chain of thought, or my dinner with my wife, or any number of other activities that were formerly sacrosanct from electronic perturbation. This has nothing to do with statistics, and everything to do with my sanity. Other people, including my wife, have decided differently, for good reasons. They carry cell phones and turn them on, and that is fine. If you want to limit your cell phone use for reasons to do with how you live, that makes sense. But don’t get rid of it because you’re afraid of brain cancer. There are a lot more sensible things to be afraid of, at least as far as we know now.

Sources: An abstract of the JAMA report referred to in this blog is freely accessible at, and Kent German’s Feb. 23, 2011 CNET article on the CTIA reaction (and other thoughts of his) can be found at;mlt_related.

1 comment:

  1. I found your blog this morning by random chance. I enjoyed reading several of your articles. Great food for thought! You are a very good writer.