The cell phone's reputation as a health risk is nearly as old as the technology itself. Worried consumers have blamed the device for everything from cancer to infertility, but with little evidence to back up these claims, experts have been split on the issue. Now California has come out with a list of guidelines in response to these supposed risks, Forbes reports.

The California Department of Public Health (CDPH) released the warning [PDF] earlier in December following a lawsuit from University of California-Berkeley researcher Joel Moskowitz. Moskowitz claimed that the state of California was putting citizens in danger by withholding information on the potential side effects of cell phone usage.

The newly released document focuses on avoiding radiofrequency (RF) energy specifically. Cell phone signals are one source of RF energy, and because it's a type of radiation, it's a common source of phone-related cancer fears. The CDPH recommends reducing exposure to the energy waves by sending text messages instead of making calls, using the speakerphone or a headset when talking on the phone, and carrying your phone in a bag rather than your bra, pocket, or belt holster. The department also suggests breaking the habit of sleeping with your phone in your bed, or at least turning it off or activating airplane mode before falling asleep.

Cell phones release more RF energy at some points than others, like when you're traveling in a vehicle, streaming or downloading content, or using a phone in an area where the signal is weak. But even when RF energy from cell phones is at its strongest, it's still not as great as the radiation from X-rays or ultraviolet rays from the Sun, and the jury's still out over whether it poses a threat to your DNA at all.

Past research linking RF energy to brain cancer has come with some major caveats: One study found that rats exposed to RF energy were more likely to develop brain tumors, but those rats were hit with seven times the radiation a person would get from a cell phone (and also they were rats, so not a perfect replacement for humans). Even the CDPH acknowledges the limits of the evidence in the studies it cites:

These studies do not establish the link definitely, however, and scientists disagree about whether cell phones cause these health problems and how great the risks might be.

So if it makes you comfortable, go ahead and sleep with your cell phone on your night stand instead of under your pillow. But maybe don't use the warning as an excuse to start declining all your calls. 

[h/t Forbes]