Ultraviolet (UV) radiation is mutagenic in a wide variety of organisms and is a major source of physical deoxyribonucleic acid (DNA) damage. The mutations caused and the biological consequences of exposing cell cultures to UV light have been extensively studied and have given many insights into the underlying mechanisms that lie behind DNA damage and repair (1 –3 ). UV radiation occurs at three wavelengths: 400 to 320 nm (UV-A), 320 to 290 nm (UV-B), and 290 to 100 nm (UV-C). Although UV-C is generally accepted to be the most harmful source of UV radiation, it occurs mainly in artificial light, as opposed to UV-A and B, which occur naturally in the environment as solar radiation.
