Cell phone emissions are radio frequency waves, which fall under non-ionizing radiation. Other sources include radio towers and Wi-Fi networks. Any object that emits waves of radio frequency must display its SAR, or specific absorption rate, which indicates the radiation load for human use. It is a different measure than mrem because it takes into account the conductivity of the human body.
"Humans are conductors," says Naidenko. "It was a big discovery to realize we had to find the source of connectivity in the body, as opposed to the general measurement."
Cell phones are a much lower-power radiation source than X-ray machines, but their impact may be greater because of the frequency of contact with the brain. In fact, some studies show that the brain is uniquely sensitive to radiofrequentic radiation, especially the still-developing brains of children.