To make clear that the U.S. Federal Communications Commission already regulates cellphones, Alsup asked that the city add this line to the fact sheet: "Although all cell phones sold in the United States must comply with RF safety limits set by the FCC, no safety study has ever ruled out the possibility of human harm from RF exposure."

"If this corrective item is unacceptable to San Francisco, then the entire program will be enjoined and San Francisco should broadcast its message at its own expense rather than compelling retailers to disseminate misleading statements," Alsup wrote.

He also wants the city to explain the significance of a warning it cites from the World Health Organization. The fact sheet should include a sentence noting that the WHO designates RF as a "possible" rather than a "known" or "probable" carcinogen.

The city must also remove images on the fact sheet that show a silhouette of a person carrying a cellphone surrounded by concentric circles. The judge thinks the image could be interpreted as indicating that cellphones are dangerous, and because he doesn't see proof that they are, he is requiring the image to be removed.

The city plans to appeal part of the order. "I disagree with his decision to limit the City's message in the way he has done. We will ask the Ninth Circuit to uphold the portion of the ruling that allows the fact sheet to go forward, but we will also ask the Court to make clear that we have even broader authority to protect the health of our people," City Attorney Dennis Herrera said.