San Francisco has passed a new law that requires all cell phone retailers to display the amount of radiation each instrument emits.
San Francisco's mayor Gavin Newsom hailed the new law as a major victory for cellphone shoppers' right to know.
According to the New York Times, the law - believed to be the first of its kind in the nation - came despite a lack of conclusive scientific evidence showing that the devices are dangerous.
Under the law, retailers will be required to post materials - in at least 11-point type - next to phones, listing their specific absorption rate, which is the amount of radio waves absorbed into the cell phone user's body tissue.
These so-called SAR rates can vary from phone to phone, but all phones sold in the United States must have a SAR rate no greater than 1.6 watts per kilogram, according to the Federal Communications Commission, which regulates the $190 billion wireless industry.
John Walls, a spokesman for C.T.I.A. - The Wireless Association, a trade group, however, warned that the new law could confuse consumers on which phones to pick or not pick.