What is Ionizing Radiation?

What is ionizing radiation? The following section, from chapter 10 of the book "Cross Currents: the Perils of Electrical Pollution" by Robert O. Becker, explains ionizing radiation and explores it's risks.

Ionizing Radiation, Nonionizing Radiation and Heat

When we first began to make use of electromagnetic energy, it was already known that the entire electromagnetic spectrum could be divided into two parts. Frequencies below those of visible light lacked the power to produce ionization of the body’s chemical structures, and those higher in frequency than visible light contained sufficient energy to do so.

Ionization is the disruption of an atom or molecule by strong electromagnetic energy, causing the ejection of electrons from the material. The resultant atom or molecule is electrically unbalanced and has a net electrical charge; in this state it is called “ionized”. Such ionized molecules are chemically very active and produce abnormal chemical reactions that are damaging to cells. From a physical point of view, it’s easy to understand how ionizing radiation can cause bioeffects. By the sane token, however, because nonionizing radiation lacks this ability, it was believed that it had no possible bioeffect except the gross production of shock or heat.

In the early 1900s, our technology was limited to the very low-frequency range of the electromagnetic spectrum (radio, for example, operated at a few thousand hertz). As our technology advanced and we began to produce higher and higher frequencies for radio transmissions, it was accidentally discovered that frequencies of about 27 million cycles (27 MHz) and higher could be generated with sufficient power to produce heating of human tissues. This led to the theory that the energy content of any electromagnetic radiation was proportional to its frequency. The higher the frequency, the greater the energy content, and vice versa. For practical purposes, the diving line for the production of heat by this radiation was set at 27 MHz. Therefore, frequencies above 27 MHz would produce proportionally more and more heating effects, while those below 27 MHz had less and less ability to do so. This was taken to indicate that any biological effect that was not the result of ionization had to the be result of heat.