Talking on your cell phone for less than an hour can increase brain activity in the area closest to the phone antenna, researchers say.
But it is still unknown how this activity will affect people’s overall health.
“The dramatic worldwide increase in use of cellular telephones has prompted concerns regarding potential harmful effects of exposure to radio frequency-modulated electromagnetic fields,” says the study, published in the Journal of American Medical Association on Wednesday.
The researchers, led by Dr. Nora D. Volkow, director of the National Institute on Drug Abuse, noted that whether cell phone radiation actually causes brain tumors is an issue that remains unresolved.
“Although we cannot determine the clinical significance, our results give evidence that the human brain is sensitive to the effects of radio frequency-electromagnetic fields from acute cell phone exposures,” Volkow said.
The study reignites a years-long controversy over the health effects of cell phone use – though it urged further studies to determine whether the increased brain activity by cell phones has any other health effects.
Researchers tested 47 participants between Jan. 1 and Dec. 31 of 2009. Cell phones were placed on each ear, and participants were not told if they were activated. On one occasion, the cell phones were off. On another occasion, the phones were muted but would receive calls and texts. After the 50-minute exposure period, each person was given a PET scan to measure their brain activity.
The results showed that when the phones were turned on, there were significant increases in the brain glucose metabolism closest to the phone antenna.
“The linear association between cell phone-related increases in metabolism and electric field strength suggests that the metabolic increases are secondary to the absorption of RF-EMF from cell phone exposures,” Volkow said. “Further studies are needed to assess if the effects we observed could have potential long-term consequences.”
In an accompanying editorial, Dr. Henry Lai of the University of Washington in Seattle and Dr. Lennart Hardell of the University Hospital in Sweden wrote about the possible effects of the emissions.
“Although the biological significance, if any, of increased glucose metabolism from acute cell phone exposure is unknown, the results warrant further investigation,” the editorial said. “An important question is whether glucose metabolism in the brain would be chronically increased from regular use of a wireless phone with higher radio-frequency energy than those used in the current study.”