A mutagen is a physical or chemical agent that can cause genetic mutation by permanently changing the genetic material, usually DNA, in an organism, thereby increasing the frequency of mutations above the natural background level

. Mutagens can be categorized as physical mutagens (e.g., radiation) or chemical mutagens (e.g., certain substances and compounds)

. The process by which an organism's DNA changes, resulting in a gene mutation, is known as mutagenesis

. Mutagens can have various implications in clinical medicine, including carcinogenesis, heritable diseases, microorganism resistance, and precision medicine

. Exposure to mutagens, such as tobacco products, radioactive substances, x-rays, ultraviolet radiation, and certain chemicals, can lead to DNA mutations that cause or contribute to certain diseases