Nonionizing Radiation

We use and are exposed to nonionizing radiation sources every day. Microwave ovens use microwaves to heat food, toasters use infrared waves to heat and sometimes burn our toast, and we watch television, talk on cell phones, and listen to the radio through the use of radio waves. These are all nonionizing forms of radiation. Visible light, radar, laser light, and ultraviolet light also fall into this radiation category.

Some forms of nonionizing radiation can damage tissues if we are exposed too much. For instance, too much ultraviolet (UV) light from lying out in the sun is known to cause some skin cancers; even moderate amounts can cause skin burns.

In addition to the sun, UV waves (sometimes called UV radiation) are emitted by lights used in tanning beds, black lights, and lights used to pasteurize fruit juices. Some UV waves have an energy that is high enough to cause a structural change within atoms.

Visible light waves are also a form of nonionizing radiation, as is the light beam emitted by a laser. A laser beam can be visible, as in the case of a laser pointer, or a laser can emit an invisible beam of UV or infrared waves. With enough energy, lasers can cause biological damage, which is why they are useful in medicine to remove warts and some skin cancers and even to break up kidney stones.

As we talk about these different sources, we are moving along a continuum of energy called the electromagnetic spectrum. Ionizing radiation tops the spectrum with the highest energy, nonionizing ultraviolet waves are next. Then comes visible light waves followed by infrared waves. Infrared sources in our daily lives include toasters, toaster ovens, and heat lamps.

Now we get down to the lower energies where our favorite devices operate—in the radiofrequency (RF) wave range. From highest to lowest energy, this includes microwave ovens, global positioning systems, cell phones, television stations, FM radio, baby monitors, cordless phones, garage-door openers, CB radios, and AM radio. Radiofrequency waves can cause tissue heating at high energies and with high intensities.

The last type of nonionizing radiation we’ll simply mention is extremely low-frequency (ELF) waves that are produced by electrical power lines and wiring.