BERKELEY, Calif. — How safe are cell phones when it comes to your health?

The Federal Communication Commission recommends keeping your phone 5 to 25 millimeters away from your body.

That means not in your pants, shirt pocket or other places on your body.

Berkely, California may the first city to require a city written warning notice with phones sold.

“If you carry or use your phone in a pants or shirt pocket or tucked into a bra when the phone is ON and connected to a wireless network, you may exceed the federal guidelines for exposure to RF [radio frequency] radiation,” is part of the proposed language. Retailers would be prohibited from selling phones that do not bear the warning: “This potential risk is greater for children. Refer to the instructions in your phone or user manual for information about how to use your phone safely.”

Now the Berkeley proposal seeks to address concerns that even as cellphones become ubiquitous in our lives, many people remain unaware of basic safety recommendations.

An April 30th survey funded by the California Brain Tumor Association (CABTA) found that 70 percent of Berkeley adults did not know about the FCC’s minimum separation distance. And 82 percent said they would like information about how far the phone should be kept from the user’s body.

The radiation guidelines, established by the FCC in 1996, assumed users would carry their cellphones at least a small distance away from the body, in a holster or belt clip, which was common practice at the time. Health activists warn cellphone users today tend to keep their phones in pockets, which means they could be exposed to much more radiation — possibly 2 to 7 times more.