A US congressman is set to propose a federal law that would put warning labels on mobile phones, just as San Francisco nears enacting an ordinance that would require retailers to post information about moible phone radiation.

On Wednesday, Ohio Congressman Dennis Kucinich said he plans to introduce a bill that would require warning labels about the potential risk of mobile phone use on the devices. The bill would also create a national research project to study mobile phones and health.

In a statement, Kucinich acknowledged that some studies find links between mobile phone use and health issues like brain tumours while others don't. "But studies funded by the telecommunications industry are significantly less likely to find a link between mobile phones and health effects," he said. "Until we know for sure, a labelling law will ensure that mobile phone users can decide for themselves the level of risk that they will accept. Obviously, mobile phone companies should not be the ones making that decision for us."

Kucinich's proposal would also call for an update to the Specific Absorption Rate, a measure of mobile phone radiation that the U.S. Federal Communications Commission requires all mobile phone makers to disclose. That standard was set decades ago and deserves an update, he said.

The CTIA cellular trade association said it supports ongoing research in this area.

"When discussing the topic of wireless communications safety, it is important to be guided by science and the conclusions of independent public health organizations and agencies," said John Walls, vice president of public affairs for CTIA. "The World Health Organization, National Cancer Institute, American Cancer Society, and the US Food and Drug Administration and Federal Communications Commission have all concurred that wireless devices are not a public health risk."

The CTIA was far more critical of the San Francisco bill, which has been passed by the city council, is awaiting signature by the mayor and would require retailers to include the SAR on display materials for phones. The stores would also have to explain what SAR means and direct consumers to further information about it provided by the city.

CTIA said that the San Francisco ordinance could mislead customers into thinking that some phones are safer than others, while the FCC has already approved all phones found in retail shops as safe.

To protest the ordinance, CTIA recently said it would stop holding one of its annual conferences in San Francisco after this year.