The possible problems with cell phones are clear. In using a cell phone, you are placing a source of electromagnetic radiation in close proximity to your brain. It doesn't take much imagination to see the potential for problems; Microwave ovens use electromagnetic radiation to cook food. Of course, cell phones operate at a different frequency and at much lower power levels than do microwave ovens, but the analog is clear. The human body evolved in an environment that did not contain significant levels of radio-frequency (rf) radiation, so it is plausible that the ubiquity of rf fields in our modem industrial world might cause some adverse health effects.