"The dramatic worldwide increase in use of cellular telephones has prompted concerns regarding potential harmful effects of exposure to radio frequency-modulated electromagnetic fields (RF-EMFs)," and the potential carcinogenic effects from those emissions, the study authors note. Yet studies trying to find a link between "cell phone use and prevalence of brain tumors have been inconsistent (some, but not all, studies showed increased risk), and the issue remains unresolved," they add.
Similarly, studies to investigate the effects of RF-EMF exposure from cell phones have yielded variable results. Dr. Nora Volkow of the National Institutes of Health and her colleagues tried to evaluate if acute cell phone exposure affects brain glucose metabolism, a marker of brain activity.
Researchers scanned the brains of 47 participants using Samsung model SCH-U310 cell phones both during phone use and with the phones deactivated. They found that whole-brain metabolism did not differ when the phones were on, but there were significant regional effects. Metabolism in the brain region closest to the antenna (orbitofrontal cortex and temporal pole) was significantly higher (approximately 7%) when the cell phones were on than when they were off.
"These results provide evidence that the human brain is sensitive to the effects of RF-EMFs from acute cell phone exposures" and "that acute cell phone exposure affects brain metabolic activity," the authors write. But the researchers are unclear how RF-EMFs could affect brain glucose metabolism.
Possible Health Consequences Are Still Unknown
The researchers also caution it's too early to draw any conclusions. "[T]hese results provide no information as to their relevance regarding potential carcinogenic effects (or lack of such effects) from chronic cell phone use." They conclude, "Further studies are needed to assess if these effects could have potential long-term harmful consequences."
Other experts are even more cautious about drawing conclusions, pointing to years of inconclusive and conflicting results from studies of cell phones. An estimated $100 million or more has been spent so far around the world on research into possible health risks from using mobile phones with no solid findings. The largest study on 420,000 mobile phone users in Denmark, found no link between phone use and cancer.
Worldwide mobile device sales to end users totaled 1.6 billion units in 2010, a 31.8% increase from 2009, according to Gartner Research. Another estimate puts shipments of mobile phones in 2010 at nearly 1.3 billion, which is worth $172.2 billion -- a number that's expected to double by 2015. By June 2010, the CTIA estimated there were 292.8 million active mobile phones in the U.S., and the estimates range between 4 billion and 6 billion phones worldwide. Whatever the true number is, it's growing rapidly.