Now that there is evidence on cell phone use's hazards, there is good reason to switch to headphones.
However; if you use a Bluetooth headphone to protect you from the radiated RF energy of the cell phone. then what will protect you from the radiated RF energy of the radio you have stuck in your ear?
So if you use wired headphones, be aware that the RF energy is absorbed in the cable, carried through the wire, then re-radiated at the headphone end!
There is a solution, use a ferrite core, tuned to 1.5-2.5 Ghz, on the cable, near to but not at the cellphone end. Not all ferrite core's are created equal. each is tuned to the frequency, or frequency range it is suppose to block. a 2 Ghz ferrite core can be ordered over the internet, Digi-key, or radio shack for 2-$6 and I strongly suggest you get a few for you and your friends.