San Francisco has rarely shied away from a legal fight over its cutting-edge laws - be it Walgreens suing over the ban on selling cigarettes in drug stores or restaurants taking the city to court over its requirement that employers provide health care coverage.

But the city's first-of-its-kind mandate requiring that retailers of cell phones label them with radiation levels has been placed on indefinite hold, and a watered-down version is likely to be passed in its place.

Then-Mayor Gavin Newsom introduced the landmark legislation last year, and it was passed on a 10-1 vote by the Board of Supervisors. It required stores to display the radiation levels alongside each phone for sale. Newsom called it a "modest, commonsense measure" to give shoppers easy access to information phone manufacturers already have.

The Cellular Telecommunications and Internet Association, a trade group representing cell phone companies, sued the city over the law, saying that all phones marketed in the United States are considered safe by the Federal Communications Commission. The association also warned that the city could have to pick up the trade group's legal fees if the city lost.

Accuracy questions

Lawyers from the city attorney's office have met with the supervisors twice in closed session in recent weeks to warn them of pitfalls in the new law and to discuss the lawsuit. Originally set to go into effect in February, implementation was delayed until May 1, then June 15. There now is no proposed start date.

Sources say it's not just the lawsuit that's giving the supervisors pause. It's also questions about the accuracy of the radiation labels, which some say could actually lead shoppers to buy phones that emit more radiation than others.

Supervisor John Avalos said he plans to introduce changes to the law, but he didn't yet have details on what they might be. "There will still be some information that's going to be shared (with buyers of cell phones), but it's going to be somewhat less," he said.

The changes will probably require cell phone retailers to hand out a tip sheet on how to lessen radiation exposure, such as using hands-free devices and not keeping the phone close to your body when you're not using it.

City officials hope this will settle the cellular group's lawsuit. The organization had no comment.

The original law required retailers to label phones with their specific absorption rate, which represents the amount of radiation a person absorbs into the body and brain when using a cell phone. The FCC requires that phones sold in the United States emit a maximum SAR level of 1.6 watts per kilogram of body tissue, though some phones emit as little as 0.2 watts per kilogram.

The cellular trade group disputes that cell phone radiation poses any health concern. Some studies in other countries have found increased rates of brain tumors and salivary gland tumors on the side of the head the user holds the phone when talking on it.

Peak readings

Joel Moskowitz, director of the Center for Family and Community Health at UC Berkeley, said the specific absorption rate isn't a very useful measure because it's the peak reading on a variety of tests conducted on cell phones to measure their radiation, but doesn't indicate the average amount of radiation a user would generally be exposed to.

He likened it to a car's gas mileage being reported only after driving it up a steep hill. Such a measurement could actually make a car shopper avoid a hybrid because it doesn't perform well on hills, even though it would generally consume less gas.

"You could buy a lower SAR phone, but on average it could produce more radiation than a higher SAR phone," he said.

Because there's no better measurement, though, cell phone users need to be diligent about limiting their exposure, he said.

Renee Sharp is the director of the California office of the Environmental Working Group, a national nonprofit research and advocacy organization that has called for consumers to have better access to data on the potential dangers of cell phones. She said SAR is an important measure that should be disclosed and should remain part of the city's law. But the trade group is "bullying the city, and they have a lot of money and they have a lot of power," she said.

Still, a watered-down version is better than nothing, Sharp said.

"We think the important thing is that San Francisco still wants to do something, and they're not letting CTIA totally win the day," she said.