This is absolutely wrong, both wired & bluetooth headsets emit around 1mWatt compared to around 2Watts that mobile phone could emit in 2G.
I refer to official headsets off-course,
Probably fake but I have an App on my phone called tawkon showing me phone radiation and providing alerts when high.
there is an app for that!
have a look at tawkon on Cydia. The best app I have seen for Jailbreak.