The most common effect is heat generation (though non-thermal biological harm has also been demonstrated), which can alter the characteristics of various bodily tissues depending on the amount of radiation present and its ability to penetrate the body. Tissue damage can promote the cellular mutations and increase your long-term risk of developing cancer.
Jump up ^ Christopher Newman, et al. v Motorola, Inc., et al. (United States District Court for the District of Maryland) ("Because no sufficiently reliable and relevant scientific evidence in support of either general or specific causation has been proffered by the plaintiffs, as explained below, the defendants’ motion will be granted and the plaintiffs’ motion will be denied."). Text
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.