By Stephen H. Wildstrom
Reader Sridhar Ganesan writes: Regarding your recent column on Bluetooth devices, I have a Bluetooth-enabled BlackBerry phone, but I have stopped using the Bluetooth headset (a Jabra 250, and a very good one at that) because I am told the radiation may be harmful to me. Have you heard anything like that?
A: Both wireless phones and Bluetooth devices emit nonionizing radiation, typically at frequencies from 1 to 2.5 gigahertz. The data on health hazards from wireless phone radiation are equivocal, with some studies showing a measure of risk and some showing no problems.
But because it's a good idea to err on the side of caution in such matters, regulatory bodies have set exposure standards. These are expressed in terms of the "specific absorption rate" (SAR), which attempts to measure the radiation actually reaching body tissue. The U.S. and Canadian governments have set a maximum SAR of 1.6 watts per kilogram, while the European Union permits a slightly higher level.
"INSIGNIFICANT BY COMPARISON."
In the real world, emissions generally stay well below the maximum allowed. According to data from BlackBerry-maker Research in Motion (RIMM ), SARs for GSM BlackBerry devices (those sold by Cingular and T-Mobile in the U.S.) fall in the range of 0.25 watts per kilogram when used at your ear.
Bluetooth radios operate at much lower power levels than phones so, not surprisingly, the radiation added by a Bluetooth headset is insignificant by comparison. A study by William G. Scanlon of Queen's University in Belfast found that a typical Ericsson (ERICY ) Bluetooth radio module generates an SAR of just 0.001 watts per kilogram.
So, if you're worried about the health impact of radio waves, remember that the phone itself is a much greater source of concern than a Bluetooth headset. That's especially true because, when you're using Bluetooth, the BlackBerry is likely positioned much farther from your body -- and especially your brain -- than when holding the phone up to your ear.