Cellphone Calls Alter Brain Activity
A 50-minute cell phone call causes a noticeable increase in brain activity in the area of the head closest to the phone's antenna, a finding by government researchers that could reinforce concerns, or at least raise new questions, about the long-term health effects of cell phones.
The study by the National Institutes of Health is one of the first, and the most prominent, to offer scientific evidence that cell phones affect brain metabolism. Results were published in today's issue of the Journal of the American Medical Association.
Scientists involved with the study said it's far too early to draw conclusions about whether electromagnetic radiation emitted from cell phones can cause tumors -- one major concern among some scientists and doctors -- or have any other negative health consequences. But their results demonstrate a need for further research.
"Unfortunately, our findings do not enlighten in any way this controversy on whether cell phones produce cancer. What they do say is that the human brain is sensitive to this electromagnetic radiation," said Dr. Nora Volkow, a director with the National Institutes of Health and lead researcher for the study. "Whether this electromagnetic radiation has any negative consequences, that is something that needs to be properly evaluated."
The possible ties between cell phone use and harmful health effects have long been a source of sometimes furious debate. On one side are those who insist that low-level electromagnetic radiation can make people ill; on the other are skeptics who say the effects on the body are minimal, if they exist at all.
Dozens of small studies on the topic have found some correlation between long-term cell phone usage and brain tumors, but most research has found no connection to cancers or any other diseases.
In response to the new study, the International Association for the Wireless Telecommunications Industry noted in a statement that research so far has "overwhelmingly indicated" that cell phones and other wireless devices are safe.
But some researchers and laypeople who worry about the widespread use of cell phones say the majority of studies haven't been thorough enough, and it could be a decade or two before industrialized nations see dramatic health consequences.
Joel Moskowitz, director of the Center for Family and Community Health at University of California at Berkeley, said he's not convinced that cell phones are dangerous, but is frustrated with the pervasive refusal by many scientists to seriously consider the possibility. He hopes the latest study -- with its association to the National Institutes of Health and publication in one of the country's major scientific journals -- will give credibility to the need to look deeper.
"This study establishes that cell phones do indeed have biologic reactivity on the brain. The (wireless) industry and scientific community seems reluctant to hear that," Moskowitz said. "I'm hoping this study will force policymakers to take this issue much more seriously and begin to encourage research in this area."
In the NIH study, which had 47 participants, cell phones were placed next to both ears while the subjects underwent brain imaging using positron emission tomography (PET scans). Participants were given an injection of glucose to measure brain activity; brain cells use glucose as a source of energy.
Subjects were scanned twice, once with both cell phones turned off, and once with the right cell phone turned on and connected to a call, but set on mute. Neither the participants nor the researchers knew when the cell phones were off or on.
When the right phone was turned on, glucose metabolism in the section of the brain nearest the antenna was about 7 percent higher than when the phone was off.
"Because the brain uses glucose when it's activated, we interpreted this to mean that the electromagnetic waves were activating the cells," Volkow said. "This type of activation, by itself we don't expect to have harmful effects. The question that remains to be studied is could there be long-term consequences from long-term stimulation."
Dr. Mitch Berger, chairman of the department of neurosurgery at University of California at San Francisco, agreed that the study demonstrates a need for further research. But he also noted that the effects on the brain weren't especially worrying.
Brain metabolism simply means the neurons have been stimulated -- a PET scan would show similar readings if someone was asked to perform a simple task like conjugating a verb -- and there's no evidence that increased brain activity is damaging, even over a long period of time, he said.
"It is a provocative study because it has shown that there is an alteration of brain metabolism. But I'm not convinced in any way, shape or form that it means something," Berger said. "I don't think you can extrapolate this to assume there's a health hazard here."
That said, he said he recognizes that almost everyone uses cell phones these days, and people are naturally curious, or even worried, about the effects of that usage on their health. With that in mind, he and other scientists, even many skeptics, recommend a simple solution: headsets.
"I don't think people should be panicked or change their usage," Berger said. "But putting distance between the device and the side of your head is a reasonable, prudent strategy until we see what happens 10 to 20 years from now."
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