For years, state health officials kept secret a set of guidelines meant to inform the public about the risks associated with cell phone use and the best practices to avoid potential harm. On Thursday, the California Department of Public Health released the guidelines, which advise cell phone users to keep the devices away from their bodies, keep calls short and to use the speaker phone on lengthy calls. The guidelines were released only after a Sacramento Superior Court judge indicated she would order them to be disclosed, and after The Chronicle told the state it was publishing a news story about the case. The two-page suggestions ... are based on studies "that suggest that long-term cell phone use may increase the risk of brain cancer and other health problems," according to the document, which includes a stamp saying it is a "draft and not for public release." The guidelines detail the effect of electromagnetic fields, or EMFs, put out by cell phones. Cell phones, according to the guidelines, release about the same relatively weak EMFs as microwave ovens, but because they are used more frequently and kept close to the body, they can "affect nearby cells and tissues." The guidelines suggest limiting cell phone use by children and teens to "texting, important calls and emergencies." People can lower their exposure by using speaker phone or a headset and not sleeping with the device or carrying it in a pocket unless it is turned off.