Bluetooth is the name of a wireless technology standard for connecting data or voice devices thus replacing cords, wires, and cables. It uses RF radiation to transmit information over short distances of generally 10 meters or less. By embedding a Bluetooth chip and receiver into products, wires that would normally carry the data or voice signal can be eliminated. In the case of cell phone headsets, the voice signal is transmitted by RF radiation from the Bluetooth device in the cell phone to a receiver/headset.
Bluetooth headset antennas emit at much lower power levels than the cell phones themselves so the RF radiation added by a Bluetooth headset is insignificant by comparison. For example, a typical Ericsson Bluetooth headset generates an SAR of just 0.001 W/kg, far below that emitted by the cell phone antenna (as mentioned previously, it can be as high as 1.6 W/kg).
Thus, if you are concerned about the health effects of RF radiation, keep in mind that the cell phone is a much greater source of radiation than a Bluetooth headset.
More information on Bluetooth headsets can be found at these websites: