06.01.11 3:46 PM ET
Are Cellphones Really a Cancer Risk?
The word “possibly” covers a lot of sins, so the decision by the International Agency for Research on Cancer, part of the World Health Organization, to classify cell-phone use as “possibly carcinogenic to humans” is about as illuminating as saying that you might possibly win the lottery: knowing something is possible doesn’t tell you what the odds are.
The IARC announcement is therefore significant not for what the panel of 31 eminent scientists from 14 nations said, but for the fact that they said anything at all. The World Health Organization is, after all, the most respected body so far to express even mild concern about the health effects of cell-phone use. Dr. Jonathan Samet of the University of Southern California, who chaired the IARC panel, said that “the evidence, while still accumulating, is strong enough to support a conclusion ... that there could be some risk, and therefore we need to keep a close watch for a link between cellphones and cancer risk.”
Good luck with that “close watch” part. In a story for Newsweek last year, I called research on the health effects of cellphones a “mess,” and that evaluation has not changed with the IARC report. The panel reviewed hundreds of scientific articles (it did not conduct any new research), and it is to the credit of the 31 scientists that they did not throw up their hands and give up in the face of a mountain of conflicting conclusions.
Consider the study that the IARC panel describes as showing “40% increased risk for gliomas in the highest category of heavy users (reported average: 30 minutes per day over a 10‐year period).” That was the Interphone study, which happened to have been organized by the IARC. It studied 10,751 adults, from very heavy users to light users to “only when my car breaks down” users. But as the Interphone scientists reported last June in the International Journal of Epidemiology, using a cellphone decreased the risk of glioma (primary brain cancer) by 19 percent. Even in people who had used cellphones for more than 10 years there was no increased risk of brain tumors. The exception: those 30-minutes-a-day-for-a-decade users, in whom the risk of glioma indeed increased 40 percent.
Interestingly, Samet offered one of the most perspicacious analyses of Interphone. Writing in the same issue of the International Journal of Epidemiology, he and a colleague pointed out that some flaw in the study accounted for the supposed decrease in brain cancer with cell-phone use. According to his calculations, the statistics were skewed in such a way as to reduce the apparent risk of using a cellphone by about 5 to 15 percent. Which means if the same flaw occurred in the calculation of risk for the heaviest users, then their increased risk is both real and greater than the reported 40 percent—and more like an 82 percent higher risk of glioma. (Any risk comes not from the phone itself, of course, but from the radio waves it emits.)
You can buy a cellphone the way you choose SPF-labeled sunscreen: by SAR, or specific absorption rate.
Other human studies that seemed to exonerate cellphones are also problematic. The first large study like this, in Denmark, found no increased rate of brain cancer, but few of the subjects had used a cell for more than 10 years; 92 percent had used one for less than five years. Brain cancer could take 30 or 40 years to develop. On the other hand—and when it comes to cellphones and cancer, there is always another hand—the study might exaggerate the true risk. If people with brain cancer unconsciously inflate their usage (“I have brain cancer, I must have used my cell for hours and hours every week”), it would falsely link brain tumors to heavy cell-phone use.
The suggestive but ambiguous, even contradictory, evidence that cellphones increase the risk of brain cancer is why the IARC panel put cellphones in the “possibly” category when it comes to cancer risks, a category that also includes pickled vegetables, coffee, DDT, the flame retardant PBB, mothballs, dioxin, and saccharin—in other words, an eclectic collection of hundreds of natural and man-made agents that evoke public reactions from “Keep that away from me!” to “Oh, come on.”
So what are the world’s 5 billion cell-phone users—many of whom consider their Androids and Nokias and BlackBerrys as indispensable an appendage as a leg—supposed to do with this information? That depends on your tolerance for risk and ambiguity, given that research on cellphones has the latter in frustrating abundance. IARC director Christopher Wild suggests that, until science produces a definitive answer, “it is important to take pragmatic measures to reduce exposure, such as hands‐free devices or texting.” Specifically:
— Headsets and Bluetooth reduce radiation exposure (though you have to switch off the Bluetooth between calls).
— Texting, by keeping the phone farther from your brain, also reduces radiation exposure.
— You can heed the little-known and little-noticed manufacturers’ warnings (usually buried somewhere in the instructions) about how far to keep a phone from the body: an inch for the BlackBerry 8300, for instance, and five eighths of an inch for the original iPhone.
— You can buy a cellphone the way you choose SPF-labeled sunscreen: by SAR, or specific absorption rate. This is a measure (in watts per kilogram) of how much of the emitted radiation is absorbed by biological tissue. The legal maximum SAR in the United States is 1.6, but SARs vary widely from phone to phone. The Motorola V195 has a maximum of 1.6, for instance, while the Samsung Infuse 4G is only 0.2. A good place to start is a database maintained by the Federal Communications Commission, here. It takes some digging, but you can also find SAR values at manufacturers’ websites, such as Motorola’s. And CNET did a terrific compilation, here.
The upshot? Taking minor precautions can’t do any harm, but switching to pay phones might be a bit premature.