Wednesday, February 23, 2011

Study: Cell Phone Use Impacts Brain Activity, Health Effects Unclear

Talking on a cell phone for close to an hour has an impact on brain activity, according to the latest research on the subject -- but the long-term health effects remain unclear.

A preliminary study in the Journal of the American Medical Association found that using the cell for 50 minutes was associated with a spike in brain glucose metabolism, which is a marker for brain activity.

The increased glucose metabolism happened in the area of the brain closest to the phone antenna, said scientists from the National Institutes of Health.

What the results mean from a health standpoint isn't yet known.

The findings are the latest in a growing and conflicting body of research on the mobile phones' potential link to cancer. Concerns have long surrounded the possible carcinogenic effects of the radiation emitted from the phones. Those waves are known as radiofrequency-modulated electromagnetic fields, or RF-EMFs.

"It's not the smoking gun," Dr. Michael DeGeorgia, a neurologist at University Hospitals Case Medical Center in Ohio, told AOL Health of the study. "It's not the final link to brain tumors. But it certainly raises provocative questions."

The authors emphasized that their research only goes so far in what it shows.

"Results of this study provide evidence that acute cell phone exposure affects brain metabolic activity," they wrote. "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 brain uses glucose for energy; how quickly it breaks down or metabolizes that glucose is an indication of how hard it is working to get that energy, explained DeGeorgia, who heads the neurocritical care center at University Hospitals.

"That can put a strain on the cells," he told AOL Health.

When cells are injured, they can either die or experience a genetic change that makes them multiply, turning on the genes that cause the cells to proliferate and turning off those that inhibit the process. That process may cause tumors to form.

"Cancer is the abnormal proliferation and growth of cells," DeGeorgia said. "One fear is that these radiofrequency waves may be stressing out the cells, may be pushing the cells over the edge. The radiofrequency from the phone can perhaps cause the genes to turn on and off."

Led by Dr. Nora D. Volkow of the NIH, the research team conducted the randomized clinical study on 47 participants between January 1 and December 31 of 2009. Cell phones were held up to both the left and right ears, while high-tech PET scans were taken of the brain and its glucose metabolism was measured. The brain's activity was monitored once when the right-ear phone was on for 50 minutes and once with both phones off.

The scientists saw no difference in the glucose metabolism of the entire brain when the phones were on versus off. But they did detect a localized effect in the region closest to the antenna: Metabolism there was about 7 percent higher when the phones were activated than when they were deactivated.

"This indicates 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 researchers wrote. "These results provide evidence that the human brain is sensitive to the effects of RF-EMFs from acute cell phone exposures."

What isn't known is how the radiation waves affect glucose metabolism in the brain, or what the potential health consequences may be.

More epidemiological trials are needed to "shed light on whether excessive cell phone use is dangerous," Dr. Steven V. Pacia, the chief of neurology at Lenox Hill Hospital, said in an e-mail to AOL Health.

"If it is true that brain metabolism increases only in regions exposed to the cell phone's RF-EMF emissions, then it is clear that cell phones produce biological effects unrelated to normal function," he said.

The NIH scientists agree, saying more work is needed to determine whether the devices can cause long-term harm.

"Studies of the association between cell phone use and prevalence of brain tumors have been inconsistent [some, but not all ... showed increased risk], and the issue remains unresolved," they wrote.

DeGeorgia said the findings don't prove a definitive association between mobile phone use and cancer. But they are significant.

"It's an illustration that radiofrequency waves are having a measurable, functional difference in the brain," he told AOL Health. "It's not a link to cancer -- they're not showing that they change the genes and cells. But it certainly shows that when you have your cell phone to your ear, your brain cells are being affected by it."

Until more is known, caution should be exercised, he added.

"Use common sense," he suggested. "If there's a way to avoid having the cell phone directly to your ear, do it, and limit the use of cell phones until all the data is in."

Source: AOL Health By Catherine Donaldson-Evans

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