noun
mutagen
A biological term for an agent that causes genetic mutation. Used in scientific contexts.
紫外線は変異原として知られている。
Ultraviolet light is known as a mutagen.
Compound of 変異 (へんい, 'mutation') + 原 (げん, 'source' or 'cause'). The exact historical derivation is uncertain, but the term is a modern scientific coinage.