The technologies underlying mobile communications are numerous and varied. Global System for Mobile Communications, or GSM, is one of the oldest and it accounts for the majority of the world's 2G networks. CDMA, or Code Division Multiple Access, is a newer development that serves as the basis for most of the world's 3G mobile technologies. Due to the differing amounts of radiation emitted by these networks, phones relying on GSM may present more health risks.
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Cell phone manufacturers are only required to list phones' specific absorption rates at maximum radiation outputs, according to Joel Moskowitz, director of the Center for Family and Community Health at the University of California at Berkeley. In a June 2011 interview with LiveScience's Natalie Walchover, Moskowitz said that these maximum values, which measure radiation absorption rates, are potentially misleading. He said that's because these values do not reflect the phones' average radiation outputs. While GSM phones typically operate at half of their maximum radiation outputs, CDMA phones operate at a fraction of their maximum outputs, emitting about 28 times less radiation than GSM phones.
The Food and Drug Administration states that there is no definitive proof that radiofrequency radiation is harmful to humans. But some studies link GSM phones more strongly to negative health effects than CDMA phones. An analysis of numerous studies on cell phones published in the November 2009 issue of the "Journal of Clinical Oncology," indicated that both types of phones decrease the body's natural resistance to tumors. However, the analysis showed that 37 percent of GSM phone studies indicated a link to tumor risks. About 15 percent of CDMA phone studies found a similar link.
While tumor risks have not been definitively linked to cell phone use, your brain is more active when using a cell phone than when speaking without one. Researchers at Deenbandhu Chhotu Ram University of Science and Technology in Sonepat, India explored these effects in a study published in the April 2011 issue of the "International Journal of Science Technology and Management." While the effects of this increased brain activity are unclear, these researchers found that GSM cell phones increase brain activity between four and 24 times greater than CDMA cell phones.
Reducing Your Risk
According to the FDA, you can reduce your risk of radiofrequency radiation exposure by spending less time on the phone by using speaker phones or hands-free headsets. Due to evidence linking greater health risks to GSM cell phones, Moskowitz suggests that you switch to CDMA-based cell phones. He advises to text instead of calling and to maintain a safe distance from your phone when speaking on it. However, as both of these technologies are understudied and potentially linked to detrimental health effects, you may opt for landlines, if you are concerned about the effects of radiofrequency radiation.