There are basically two types of electromagnetic radiation Ionizing (high frequency) and Non-Ionizing (low frequency). While cell phones tend to be in the lower level RF spectrum, they still may be doing damage to you. Not sure why, but it looks like Motorola has 5 of the 10 highest radiation phones according to cellphones.org.
Why risk it? Get your self a wired headset or speakerphone system, don't keep your phone glued to your hip (that is mucho nerdy anyway), don't sleep with your cell phone on your nightstand 3-inches from your head, etc,