ABSTRACT
Radiation is a form of energy whose sources are both synthetic and naturally occurring. Small quantities of radioactive materials occur naturally in the environment and cause what is referred to as internal exposure. External exposure results from sunlight radiation and from synthetic and other naturally occurring radioactive materials. Radiation energy above the ultraviolet (UV) range is called ionizing radiation because of the ability of photon energy to displace electrons from their atomic nuclei. Nonionizing radiation occurs at frequencies below the visible spectrum. UV rays are of lower frequency and longer wavelength than ionizing radiation. Unlike ionizing radiation, skin damage induced by UV rays is mediated principally by the generation of reactive oxygen species and the interruption of melanin production. Squamous cell carcinoma, basal cell carcinoma, and malignant melanomas are high-risk tumors associated with prolonged exposure to UV rays. Nonionizing radiation emanates from sources with lower energy and longer wavelengths.
