For many young women today, tucking cell phones in the bra has become a cool, hip way to have simple access to these essential devices. Most of us have no idea that cell phones are small microwave radios that should not be kept directly on the body.

The ways some people are using their phones today could increase their risk of developing breast cancer and other diseases tomorrow. Cell phone’s microwave radiation seeps directly into soft fatty tissue of the breast.

It’s too late for Andrea X, a young active mother of three from Southern California. For more than six years, this vegetarian and runner drove her children everywhere, with her cell phone tucked snugly into her sports bra. She used her hands-free headset and was on the phone for four to five hours a day. Often her chest or ear would redden, but she thought little of it. This spring she developed a malignant tumor right where her phone had sat on her breast. No one in her family has ever had breast cancer.

Could all this be a coincidence? Of course. But her doctor, and the physicians of four other women under the age of 40 with similar stories, are deeply concerned that cell phones can cause cancer in women who store them on their torsos.

As of January, San Francisco will require cell phone retailers to provide the estimated Specific Absorption Rate (SAR) for each phone. I am not asking anyone to become a Luddite and forgo the benefits and wonders of modern technology. I am saying — know the dangers of holding phones next to the brain and body, and be safe. Using a headset or speaker phone substantially reduces radiation exposure, as does holding a phone away from the body when it’s connected to a signal.

Interestingly, smart phones come with warnings, but these warnings are buried in the manufacturers’ instruction material that few people read. The iPhone 4 manual, for example, says that if the phone is kept in the pocket, “FCC guidelines for safe exposure can be exceeded,” and that “users are responsible for protecting themselves.”

Amazingly, today’s SARs rest on standards that were set in 1979 to prevent the warming of the large head of a 6-foot tall heavy-set man.

Our bodies are truly electric. But the steady, low electrical impulses that keep us alive may be disrupted by those pulsed signals that power today’s small microwave radio cell phones. That warm tingle from the cell phone pressed to the bosom could presage breast cancer not too far into your future. Given even the possibility of harm that can be prevented with a dollop of precaution, isn’t it time, ladies, to get a headset, and take those phones out of your pockets and bras?

Devra Davis is an epidemiologist, author and public health advocate. Davis’ new book is “Disconnect: The Truth About Cell Phone Radiation, What the Industry Has Done to Hide It, and How to Protect Your Family.”

CELL PHONES AND BREAST CANCER RESOURCES