A US phone industry group is suing the city of San Francisco to stop a law that requires mobile phone stores to post how much radio energy each model emits.
It's the first law of that kind in the US. The industry trade group known as CTIA - The Wireless Association said the law will mislead consumers into thinking that one phone might be safer than another on the basis of radiation measurements.
Studies have not conclusively found that mobile phone radiation is a health risk. Research continues on brain tumors.
In its lawsuit filed in the US District Court in San Francisco, the industry group said the city is usurping the authority of the Federal Communications Commission, which sets limits for phone radiation.
The city attorney's office said it had not seen the lawsuit and was unable to comment.
Previously, Mayor Gavin Newsom's office has said that the ordinance is "a quite modest measure that will provide greater transparency and information to consumers for whom this is an area of interest or concern".
The local ordinance requires mobile phone retailers to disclose a measure of much energy will theoretically be absorbed by a user's head. FCC limits this specific absorption rate, or SAR, to an average of 1.6 watts per kilogram. Measurements for phones sold in the US are available on the agency's site, but not usually in stores.
"Nobody should be suggesting to consumers that they ought to be shopping for phones based on a difference in SAR values," said John Walls, vice president for public affairs at CTIA. "There's no scientific basis to suggest, as the ordinance does, that two phones with different values have a safety distinction between them," as long as they're below the FCC's limit."
San Francisco is known for novel legislation. It has banned plastic grocery bags, ended municipal use of bottled water, made composting mandatory and required the posting of nutrition information in restaurants.