Elevated brain glucose metabolism, a marker of brain activity, showed up in a study designed to assess whether cell phone exposure affected regional activity in the human brain, led by Nora Volkow, MD, of the National Institutes of Health.
Dr. Nora Volkow (Photo courtesy NIH)
The study, published in today's issue of the "Journal of the American Medical Association," is the first investigation in humans of glucose metabolism in the brain after cell phone use.
"Fifty-minute exposure to a cell phone was associated with increases in glucose consumption by the brain, which indicates that the brain was being activated by the radiofrequencies from the cell phone," said Dr. Volkow.
"Even though the radiofrequencies that are emitted from current cell phone technologies are very weak, they are able to activate the human brain - they have an effect," said Dr. Volkow, a specialist in brain activity who serves as director of the National Institute on Drug Abuse and works with the National Institute on Alcohol Abuse and Alcoholism.
The randomized study was conducted between January 1 and December 31, 2009 at a single U.S. laboratory among 47 healthy participants recruited from the community.
Child on a cell phone (Photo by Maggie Barnidge)
Cell phones were placed on their left and right ears and brain imaging was performed with positron emission tomography, PET, scans. The imaging was used to measure brain glucose metabolism twice, once with the right cell phone activated but sound muted for 50 minutes - the "on" condition - and once with both cell phones deactivated - the "off" condition.
The PET scans were compared to assess the effect of cell phone use on brain glucose metabolism.
The researchers found that whole-brain metabolism did not differ between the on and off conditions. But metabolism in the brain region closest to the antenna was approximately seven percent higher for cell phone on than for cell phone off conditions.
The researchers say that the mechanisms by which radio frequency and electromagnetic fields, RF-EMFs, could affect brain glucose metabolism are "unclear."
The study does indicate that "the regions expected to have the greater absorption of RF-EMFs from the cell phone exposure were the ones that showed the larger increases in glucose metabolism," the authors write. "These results provide evidence that the human brain is sensitive to the effects of RF-EMFs from acute cell phone exposures."
With an estimated five billion cell phones in use around the world today concerns have been raised by the possibility that RF-EMFs emitted by cell phones may induce brain cancer.
Five billion cell phones are in use around the world. (Photo by vilchez87)
This study's authors say more research is needed to answer that question.
"Results of this study provide evidence that acute cell phone exposure affects brain metabolic activity," the authors state. "However, these results provide no information as to their relevance regarding potential carcinogenic effects, or lack of such effects, from chronic cell phone use."
The results of this study add information about the possible effects of radiofrequency emissions from wireless phones on brain activity, write Henry Lai, PhD, of the University of Washington and Lennart Hardell, MD, PhD, of University Hospital, Orebro, Sweden, in an editorial accompanying the JAMA article.
"Although the biological significance, if any, of increased glucose metabolism from acute cell phone exposure is unknown, the results warrant further investigation," write Lai and Hardell.
"An important question is whether glucose metabolism in the brain would be chronically increased from regular use of a wireless phone with higher radiofrequency energy than those used in the current study," they write. "Potential acute and chronic health effects need to be clarified."
Lai and Hardell question whether the findings Volkow and her team may be a marker of other alterations in brain function from radiofrequency emissions, such as neurotransmitter and neurochemical activities.
"If so, this might have effects on other organs, leading to unwanted physiological responses," write Lai and Hardell. "Further studies on biomarkers of functional brain changes from exposure to radiofrequency radiation are definitely warranted."
Writes Louis Slesin in "Microwave News, "The new finding, if confirmed, would at the very least force a rethink of the prevailing orthodoxy, which maintains that low levels of RF and microwave radiation are too weak to have any effect and can be disregarded."
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