what is a mutagen

A mutagen is a physical or chemical agent that can cause permanent changes in genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background. Mutagens can be of physical, chemical, or biological origin, and examples include tobacco products, radioactive substances, x-rays, ultraviolet radiation, and a wide variety of chemicals. Exposure to mutagens can produce DNA mutations that cause or contribute to certain diseases, including cancer. Mutagens can cause changes to the DNA and are therefore genotoxic. They can affect the transcription and replication of the DNA, which in severe cases can lead to cell death. The mutagen produces mutations in the DNA, and deleterious mutation can result in aberrant, impaired, or loss of function for a particular gene, and accumulation of mutations may lead to cancer. Mutagens may therefore be also carcinogens.