You’ve heard the warnings--turn off your cell phone on an airplane; don’t use your phone inside a hospital--and the horror stories of car accidents and brain tumors caused by cell phones. So, how real are the risks of cell phones?

Cell Phones and Brain Cancer

Cell phones produce electromagnetic radiation of a frequency somewhere between what comes out of a television and what comes out of a leaky microwave oven. This radiation penetrates the brain, a short distance from the phone's antenna, and could theoretically cause damage by heating up the brain’s cells.

The heating is slight, however, as the electromagnetic radiation from cell phones is different from the ionizing radiation, found in X-rays, which damages DNA and is linked to cancer.

According to researchers, studies have shown that the radiation from cell phones does not cause cancer.

Cell Phones Interfering With Hospital Equipment

The chances of your cell phone causing a major problem in a hospital are slight, according to one study.

The study examined the affects of cell phones on heart and lung monitoring devices used in hospitals. While the phones did cause interference, the interference was not enough to cause concern.

However, the tests were conducted on devices that were not being used on patients. Researchers say that more tests need to be done to determine the extent of cell phone interference on these devices when patients are actually connected to them.

Cell Phones and Airplanes

NASA's Aviation Safety Reporting System's "Passenger Electronic Devises Database Report Set" contains several reports of incidents "personal electronic devices" seemed to create disturbances in aircrafts' electronic systems.

Controlled tests have also shown that cell phones can, indeed, interfere with avionics equipment on airliners. In the tests, the exact position of the cell phone on the aircraft made a big difference, as levels of interference varied significantly as cell phones were moved throughout the fuselages of test aircraft.

Another fear is that cell phones may interfere with navigation and other aircraft systems.

Aside from interference to airplanes, the Federal Communication Commission bans the use of cell phones on airplanes because they could interfere with cell phone systems on the ground.

Cell phones were designed for use on the ground, where the nearest node will pick up the call’s signal. From the air, moving at several hundred miles an hour, your cell phone’s signal could reach miles and hit many nodes at the same time, causing a disruption.

Cell Phones and Driving

One state, and many cities, requires that drivers use a hands-free headset if they want to use a cell phone while driving. However, although the devices leave hands free, the driver may still be distracted.

According to research, having a telephone conversation while driving hinders driving ability. One study found that using a cell phone while driving increases the risk of crashing by four times, and a hands-free device didn’t change the risk.

Another study, which evaluated the driving abilities of college students while talking on cell phones, found they students missed traffic signals and reacted more slowly to events when they were using either a cell phone or a hands-free device. Comparatively, when the students only listened to the radio or an audio book, there driving was less affected.

CNN Money January 30, 2003