On Aug. 7, 1996, the FCC created guidelines on cell phone radiation (RF) exposure with input from the Food and Drug Administration (FDA), the Environmental Protection Agency (EPA), the National Institute for Occupational Safety and Health (NIOSH), and the Occupational Safety and Health Administration (OSHA).
The guidelines created a measure of the rate that body tissue absorbs radiation during cell phone use called the specific absorption rate (SAR). The SAR for cell phone radiation was set at a maximum of 1.6 watts of energy absorbed per kilogram of body weight. The limit was set due to the thermal effects of cell phone radiation (all RF radiation can heat human body tissue at high enough levels) - it was not set to mitigate other biological effects cell phone radiation might have such as DNA damage or cancer.
The FCC SAR limit is based upon a cell phone call that averages 30 minutes when the cell phone is held at the ear. Holding a phone away from the body or using a wired earpiece lowers the amount of radiation absorbed, and text messaging rather than talking, further lowers that amount.
V. Find Your Phone: FCC Database on cell phone radiation (SAR) levels
The FCC maintains a database that includes the SAR - radiation absorption - levels for every certified cell phone sold in the United States.
You can find the SAR for your individual cell phone by typing the FCC ID number of your cell phone into the FCC database available here: http://www.fcc.gov/oet/ea/fccid
From the FCC website: "The FCC ID number is usually shown somewhere on the case of the phone or device. In many cases, you will have to remove the battery pack to find the number. Once you have the number proceed as follows. Go to the following Web address: www.fcc.gov/oet/ea/fccid. Once you are there... Enter the FCC ID number (in two parts as indicated: 'Grantee Code' is comprised of the first three characters, the 'Equipment Product Code' is the remainder of the FCC ID). Then click on 'Start Search.' The grant of equipment authorization for this particular ID number should appear. The highest SAR values reported in the equipment certification test data are usually included in the comments section of the grant of equipment certification."