As you know, this issue is very controversial. the cell phone industry has a lot of money fighting any independent studies and produce their own funded studies saying there is no risk. (It is a lot like the oil companies and global warming.)
This site offers an interesting alternative:
“Airtube headsets are a powerful line of defense against cell phone radiation. Regular headsets and blue tooth headsets simply do not offer the same quality of protection as the RF3 headsets do.
As a matter of fact, blue tooth headsets transmit the same or higher level of radiation that a cell phone does, only it is not only at your ear, it is in the sensitive tissues of your ear and closer to your brain.
Headsets that are wired can act like an antenna, transmitting electromagnetic fields (emf) to your head.
An airtube works like a stethoscope. It has a regular wired connection from the phone, but then has a hollow tube which provides a safe gap between you and the harmful radio frequencies (RF) coming from your phone.”