Radiation from a mobile phone call can make brain regions near the device burn more energy, according to a new study. 
 
 Cellphones emit ultra-high-frequency radio waves during calls and data transfers, and some researchers have suspected this radiation — albeit inconclusively — of being linked to long-term health risks like brain cancer. The new brain-scan-based work, to be published Feb. 23 in the Journal of the American Medical Association, shows radiation emitted from a cellphone’s antenna during a call makes nearby brain tissue use 7 percent more energy. 
 
 “We have no idea what this means yet or how it works,” said neuroscientist Nora Volkow of the National Institutes of Health. “But this is the first reliable study showing the brain is activated by exposure to cellphone radio frequencies.” 
 
 More than 5 billion mobile devices may be in use worldwide today. From behavioral quirks to brain cancer, researchers have looked for any health risks associated with cellphone radiation for years. Volkow said, however, that most research has produced conflicting results. 
 
 “These studies used only 14 people, at most, and looked at brain activity over brief time spans of about 60 seconds. A cellphone’s effect on the brain is very weak, so you lose statistical power with small sample sizes and durations,” said Volkow. “Our study had 47 usable subjects monitored over a long time to get us significant data.” 
 
 Cancer epidemiologist Geoffrey Kabat of the Albert Einstein College of Medicine said the work can’t and doesn’t offer any clinical predictions, but regarded it as the best to date on cellphone radiation’s effects on the brain. 
 
 “It’s a really even-handed look at this problem, and it shows a small effect that scales with exposure,” said Kabat, author of the book Hyping Health Risks. 
 
 Cellphones use ultra-high-frequency radio waves to connect with telecommunications networks. Antennas within phones emit the waves and, while the strength tails off quickly as distance from the antenna increases, a sizable chunk of it is beamed through the brain. 
 
 As a result, federal agencies require phone manufacturers to post information about how much radiation the body might absorb for each model, called its Specific Absorption Rate or SAR. Measured in watts per kilogram of tissue, it reveals how much radiation parts of the body are exposed to during use of a mobile device. 
 
 The simple cellphone used in Volkow’s study, a Samsung Knack phone popular in New York, has a peak SAR in the head of just under 1 watt per kilogram of tissue. The Phone 4 has a peak SAR in the head twice as high, while the sun’s average SAR can be 5 watts per kilogram across the body during sunbathing. 
 
 Some studies have suggested a small yet significant link between long-term cellphone SARs and certain brain cancers, including glioma, but most investigations have found no significant links. To help abolish uncertainty, the World Health Organization tasked a group of scientists around the world to research cellphone use and cancer. Their 2010 Interphone report showed no substantial link with mobile phone use and incidence of brain cancers, aside from a very small risk increase for long-term heavy users, and in fact found reduced rates for some types. 
 
 ‘The effect is very small, but it’s still unnatural. Nature didn’t prepare our brains for this.’ 
 
 Still, Volkow said, understanding close-up and long-term exposure to cellphone radiation is important. 
 
 “The state of knowledge is really speculative. No studies have determined mechanisms for what we have seen, or other effects such as increased blood flow in the brain,” Volkow said. “I have spent hours on the phone with my sister every week, and have done it for years, so I would like to know if that’s harmful or not.” 
 
 Volkow and a team of researchers scanned the brains of 47 people with a cellphone attached to each side of their head. One phone was turned off, while the other had an active call going for 50 minutes. It was muted to prevent the audio from having effects on brain activity. 
 
 Twenty minutes into the call, clinicians injected a radioactive form of sugar into each person, then began imaging their brains with a Positron Emission Topography machine. Over the course of 30 minutes, the sugar pooled in the brain’s most active regions and revealed the energy use to the brain scanner. 
 
 Accounting for normal activity, the subjects showed about a 7 percent boost in sugar use on the side of the head where the active cellphone was. 
 
 Brain imaging physicist Dardo Tomasi of Brookhaven National Laboratory, who co-authored the study, said that’s several times less activity than visual brain regions show during an engaging movie. 
 
 “The effect is very small, but it’s still unnatural. Nature didn’t prepare our brains for this,” Tomasi said. 
 
 Although the mechanism for the effect and its long-term consequences aren’t known, Volkow said it’s cheap and worthwhile to take matters into your own hands. 
 
 “You don’t have to wait around on us for the answers. Just use a wired headset or the speakerphone function,” she said. “That keeps the phone far enough away to make it an insignificant risk.” 
 
 Image: A bottom-of-the-brain view showing average use of radioactive glucose in the brains of 47 subjects exposed to a 50-minute phone call on the right side of their head. (Nora Volkow/JAMA) 
 
 See Also: ||||| Abstract 
 
 Context The dramatic increase in use of cellular telephones has generated concern about possible negative effects of radiofrequency signals delivered to the brain. However, whether acute cell phone exposure affects the human brain is unclear. 
 
 Objective To evaluate if acute cell phone exposure affects brain glucose metabolism, a marker of brain activity. 
 
 Design, Setting, and Participants Randomized crossover study conducted between January 1 and December 31, 2009, at a single US laboratory among 47 healthy participants recruited from the community. Cell phones were placed on the left and right ears and positron emission tomography with (18F)fluorodeoxyglucose injection was used to measure brain glucose metabolism twice, once with the right cell phone activated (sound muted) for 50 minutes (“on” condition) and once with both cell phones deactivated (“off” condition). Statistical parametric mapping was used to compare metabolism between on and off conditions using paired t tests, and Pearson linear correlations were used to verify the association of metabolism and estimated amplitude of radiofrequency-modulated electromagnetic waves emitted by the cell phone. Clusters with at least 1000 voxels (volume >8 cm3) and P < .05 (corrected for multiple comparisons) were considered significant. 
 
 Main Outcome Measure Brain glucose metabolism computed as absolute metabolism (μmol/100 g per minute) and as normalized metabolism (region/whole brain). 
 
 Results Whole-brain metabolism did not differ between on and off conditions. In contrast, metabolism in the region closest to the antenna (orbitofrontal cortex and temporal pole) was significantly higher for on than off conditions (35.7 vs 33.3 μmol/100 g per minute; mean difference, 2.4 [95% confidence interval, 0.67-4.2]; P = .004). The increases were significantly correlated with the estimated electromagnetic field amplitudes both for absolute metabolism (R = 0.95, P < .001) and normalized metabolism (R = 0.89; P < .001). 
 
 Conclusions In healthy participants and compared with no exposure, 50-minute cell phone exposure was associated with increased brain glucose metabolism in the region closest to the antenna. This finding is of unknown clinical significance. ||||| The electromagnetic radiation emitted by a cellular phone's antenna appears to activate nearby regions of the brain to unusually high levels, according to a study published Tuesday in the Journal of the American Medical Assn. that is likely to spark new concerns about the health effects of wireless devices.The preliminary study, led by a respected neuroscientist at the National Institutes of Health , raises many more questions than it answers. But by providing solid evidence that cellphone use has measurable effects on brain activity, it suggests that the nation's passionate attachment to its 300 million cellphones may be altering the way we think and behave in subtle ways.Researchers peered inside the brains of 47 healthy subjects using positron emission tomography, also known as PET scanning, to measure the location and timing of brain activity by detecting signs that cells were consuming energy. They found that despite official skepticism that cellphones' electromagnetic energy exerts any influence on nearby cells — including statements issued by the Food and Drug Administration — it clearly does."Because there's been such a massive expansion in cellphone use these past 15 to 20 years, it behooves us to try to understand whether, if we use these devices repeatedly and intensively for years, do they have lasting effects?" said study leader Dr. Nora Volkow, director of the National Institute on Drug Abuse , who researches how addiction affects the brain.Those effects could vary widely depending upon the location of a cellphone's antenna, the frequency on which it operates, and how long one uses the device, Volkow said.What the study does not suggest is that cellphone use contributes to the development of brain cancers. Although that concern is pressed adamantly by activists, a growing body of research has failed to find evidence to support it.The study found that two areas of the brain close to the phone's antenna, which was embedded in the mouthpiece of the phone used, showed unusual increases in activity throughout a 50-minute period of live transmission. The researchers speculated that a cellphone with its antenna placed elsewhere — near the phone's earpiece, for instance — might activate different regions in the brain.That the heightened activity occurred closest to the antenna, and not near the place where the phone was in direct contact with the head, signaled to the study's authors that the changes were a response to electromagnetic signals and not a reaction to the heat generated by the device. The FDA has taken the position that any harmful effects of cellphones are the result of tissue becoming overheated by direct exposure to the device as it warms with prolonged use.Researchers also were careful to rule out that the increased brain activity was a response to language or other sounds heard over the phone. In their "live" phase, the phones in the experiment were connected to a recorded message, but the audio signal was muted, so subjects heard nothing."It's a surprising finding," said Dr. Keith L. Black, chairman of neurosurgery at Cedars-Sinai Medical Center in Los Angeles, who wasn't involved in the study. "We normally don't expect the brain to be activated unless it's in response to stimulation, or unless it's in a pathological state such as epilepsy."That the mere proximity of an electromagnetic radiation source could stimulate activity in the brain is potentially significant, Black added. "We don't know whether this is a good effect, a neutral effect or a bad effect — and if it is a bad effect, we don't know what kind of exposure is required" to cause harm, he said. That should come with further research.In an editorial accompanying the study, University of Washington bioengineer Henry Lai and Swedish oncologist Lennart Hardell wrote that the study raises questions that are potentially worrisome.For starters, they asked whether the brain activity observed in the study may have resulted from a shift in the levels or action of certain brain chemicals, such as the neurotransmitters dopamine and serotonin. Because those chemicals play crucial roles elsewhere in the body, changes brought about by cellphone use could have unpredictable health effects far from the brain, they wrote.Lai and Hardell also wondered whether regular use of wireless devices would prompt chronic stimulation of certain parts of the brain, and whether such stimulation could, over time, have unpredictable effects.
– The debate on the health risks of cell phones is probably going to get noisy for a few days. A prominent new study shows that if you use the phone for about an hour, the area of your brain nearest the antenna shows increased activity, reports Wired. “We have no idea what this means yet or how it works,” said the lead researcher, Nora Volkow of the National Institutes of Health. “But this is the first reliable study showing the brain is activated by exposure to cellphone radio frequencies.” The study is in the Journal of the American Medical Association and can be read in full here. "I can't overall say this is harmful but we have to study more for long-term effects," says Volkow. In the meantime, the by-now common advice to use a headset or speaker phone—especially teens, whose brains are more vulnerable—is probably wise, she says. The Los Angeles Times notes that the study may not be definitive, but "by providing solid evidence that cellphone use has measurable effects on brain activity, it suggests that the nation's passionate attachment to its 300 million cellphones may be altering the way we think and behave in subtle ways."