A:
I just Googled the topic, now I kinda wish I hadn't ;-)
I was surprised to find a couple things:
--Bluetooth does emit the same radiation as a cellphone, however, it's at least 100 times less. A couple things to consider though. If you're not on a call and you leave your headset in, you're getting 'pulsed' with radiation -- less than if on a call, but the headset does stay active. Also, if you have your phone in your pocket you're exposing your internal organs in that area while you're zapping your head with the headset. Cellphones emit the same level of radiation regardless of whether you're using a Bluetooth headset for calling. Bluetooth 4.x emits extremely low levels of radiation while in 'standby' compared to earlier Bluetooth versions.
There are limited studies on the health effects of cellphone radiation, and virtually no studies on the health effects of Bluetooth.