First, though there has been a great deal of research, the evidence pointing to any health hazard from radiation in the 800 MHz to 2 GHz range at the power levels used by mobile phones is, at worst, equivocal. This suggests that if there is any risk at all, it is very small. Second, I have not seen any studies suggesting any risk from Bluetooth. This is not surprising. While a phone needs to transmit with enough power to reach a base station antenna that may be a couple of miles away, Bluetooth has a nominal range of 30 feet.

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.

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