The energy of electromagnetic radiation is determined by its frequency; ionizing radiation is high frequency, and therefore high energy, whereas non-ionizing radiation is low frequency, and therefore low energy. The NCI fact sheet Electromagnetic Fields and Cancer lists sources of radiofrequency radiation. More information about ionizing radiation can be found on the Radiation page.
EWG believes that cell phone testing procedures should include cases and other accessories, whether supplied by the phone manufacturer or a third party. Since these cases and accessories have no other use and have the potential to influence the phone’s transmitting and receiving activity and the amount of radiation that a user might encounter, they fall within FCC’s authority.
Over time, the number of cell phone calls per day, the length of each call, and the amount of time people use cell phones have increased. Because of changes in cell phone technology and increases in the number of base stations for transmitting wireless signals, the exposure from cell phone use—power output—has changed, mostly lowered, in many regions of the United States (1).