Brain cancer patients and people who've lost loved ones to the disease demonstrated outside the CTIA; The Wireless Industry Association's trade conference at Moscone Center. The protesters believe cell phones caused the cancer.
"My own husband has a brain tumor that has been linked by the experts to his long-term cell phone use," says Ellie Marks from Environmental Health Trust.
But association spokesman John Walls says there's no scientific evidence of a link between cell phones and cancer.
"You look at organizations like the World Health Organization, NIH [National Institutes of Health], or the National Cancer Institute, FDA, FCC, American Cancer Society -- a pretty long list of conclusions by those agencies that say there's no evidence if any concern, any risk," says Walls.
"When you take away some of the telecomm industry-funded studies, the weight of the evidence is conclusive that cell phones are causing gliomas and acoustuic neuromas," says Marks.
UC Berkeley physicist Richard Muller, Ph.D., says cell phones are not powerful enough to produce harmful radiation.
"The small bit of microwave radiation you can get from a cell phone, we know of no mechanism that can hurt the body or can cause cancer or any of those things," says Muller.
The San Francisco Board of Supervisors voted this year to require cell phone radiation levels are to be disclosed wherever they're sold in the city. Stores will have to start displaying emission ratings in February; chain stores have until 2012.
Walls says what the board has done is irresponsible and misleading, because all phones meet the same federal standard.
"That standard by science tells us there's not a safe, safer, safest. They're all safe," says Walls.
CTIA is suing the city over the law and will not be coming back to San Francisco for its convention.
"We think the city has sent us a very clear message that we weren't wanted here," says Walls.
Mayor Gavin Newsom has said the new law is a modest, common sense measure makes already-available information more accessible.