(radiation exposure) Exposure to radioactive materials or ionizing radiation, whether by external irradiation, contact or contamination with radioactive material, or incorporation of radioactive materials, as in the case of certain diagnostic procedures.

(radiation exposure) Phenomenon in which organisms are subjected to radiation.

(radiation exposure) Radiation is energy. It travels in the form of energy waves or high-speed particles. Radiation can occur naturally or be man-made. There are two types: Non-ionizing radiation, which includes radio waves, cell phones, microwaves, infrared radiation and visible light; Ionizing radiation, which includes ultraviolet radiation, radon, x-rays, and gamma rays. Background radiation is all around us all the time. Most of it forms naturally from minerals. These radioactive minerals are in the ground, soil, water, and even our bodies. Background radiation can also come from outer space and the sun. Other sources are man-made, such as x-rays, radiation therapy to treat cancer, and electrical power lines. Radiation has been around us throughout our evolution. So our bodies are designed to deal with the low levels we're exposed to every day. But too much radiation can damage tissues by changing cell structure and damaging DNA. This can cause serious health problems, including cancer.