If you're serious about doing research on this, the near field radiation figures are the most important to the user. Of course the radiation isn't as dangerous as the actual insertion of the cell phone into your ear that takes place when the Mack runs over your Miata.
You might take a looke at
http://www.electric-words.com/ which turned up on a quick search I did. If you want to do a thorough search, I'd suggest a Boolean search on the key terms (cell phone) and (near field radiation) or slight variations on the theme. RF is considered "non-ionizing" radiation, so that's another search term to combine with "cell / cellular phone".
Unfortunately, no really good, thorough studies have been done on near field strength. The U.S. feds base their safety evaluations on criteria other than near field strength. A stupid, stupid thing to do.
Regards,
Jim