Using a mobile phone for 50 minutes stirs brain metabolism, although the health consequences are unknown and need to be studied further, U.S. researchers said.
When mobile phones were on and held against the ear, brain glucose metabolism, a marker of brain cell activity, was about 7 percent higher in areas closest to the antenna than when phones were off, a study in today’s Journal of the American Medical Association found. The study, the first to show the effects of mobile-phone use on brain metabolism, was done by researchers from the National Institutes of Health in Bethesda, Maryland, and Brookhaven National Laboratory in Upton, New York.
Studies, including a report last year from the World Health Organization’s International Agency for Research on Cancer, have produced conflicting results over the health dangers of mobile phones, particularly their link to cancer. Today’s finding shows that human brain metabolism is sensitive to the effects of radiofrequency-electromagnetic fields, a form of radiation, from mobile phones.
“We need to investigate this carefully so that we can send a clear-cut message that is as unequivocal as possible,” said Nora Volkow, director of the National Institutes of Health’s National Institute on Drug Abuse, in a Feb. 18 telephone interview. “We don’t know the clinical significance. In principle, increasing brain glucose metabolism is not a bad thing. You don’t need to stop using your cell phones. If you are concerned, use a wire ear piece or use your speaker phone mode.”
There were almost 293 million wireless accounts in the U.S. as of June 2010, according to CTIA-The Wireless Association, a Washington-based trade group that represents carriers, phone makers and suppliers. The number of U.S. households that only have wireless phones was about 25 percent, the group said.
“The peer-reviewed scientific evidence has overwhelmingly indicated that wireless devices, within the limits established by the FCC, do not pose a public health risk or cause any adverse health effects,” John Walls, vice president of public affairs for CTIA, said in a Feb. 18 e-mail. “The leading global health organizations such as the American Cancer Society, National Cancer Institute, World Health Organization and the U.S. Food and Drug Administration all have concurred that wireless devices are not a public health risk.”
The researchers from the National Institutes of Health and Brookhaven National Laboratory included 47 people in the study. They placed mobile phones on the right and left ears of participants and then measured brain glucose metabolism once when the phone on the right side was on but muted for 50 minutes and a second time when both cell phones were off. After 50 minutes, the patients had their brain activity measured using a positron emission tomography, or PET, scan.
Affected Brain Regions
Researchers found that only the regions closest to the antenna, the orbitofrontal cortex and the temporal pole, saw a rise in brain metabolism when the mobile phone was on. The orbitofrontal cortex plays a role in decision making and reward and punishment, and the temporal pole is involved in social and emotional processes.
Henry Lai, who wrote an accompanying editorial in the journal with Lennart Hardell from University Hospital in Orebro, Sweden, said the results of today’s study add to information about the possible effects of emissions from wireless phones on the brain.
“It is an intriguing discovery and it certainly adds to the concern that cell phone use is not completely safe,” said Lai, a bioengineering researcher at the University of Washington in Seattle, in a Feb. 20 e-mail. “Before we understand the impact of the results of this study, people who use cell phones should limit their exposure to the radiation, particularly to the head.”
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