A substance or agent that causes an increase in the rate of change in genes (subsections of the DNA of the body's cells). These mutations (changes) can be passed along as the cell reproduces, sometimes leading to defective cells or cancer. Examples of mutagens include certain biological and chemical agents as well exposure to ultraviolet light or ionizing radiation. Mutagenesis is the formation of mutations. Additional Info: There are many types of mutations, some of which are harmful and others which have little or no effect on the body's function. See: The DNA and Mutations a clear, multi-page resource at the U of California at Berkeley. Mutagens can be identified using the Ames test and other biochemical testing methods. Do not confuse a mutagen with a carcinogen (a substance that causes cancer). Mutagens may cause cancer, but not always. Do not confuse a mutagen with a teratogen (a substance that causes change or harm to a fetus or embryo). MSDS Relevance: Avoid working with mutagens whenever possible. If you must work with a mutagen be sure to wearpersonal protective equipment (PPE) and utilize workplace controls such as a fume hoods to minimize your exposure. See also: Carcinogen, Clastogen, Cytotoxin, Teratogen