It is if it serves a purpose, has a meaning, which is not provided by another word. It means, presumably, treated by adding chemicals, additives. What word is there for that? The test is not whether it's in a dictionary yet. It will be if it has currency, even if it is only used by scientists or engineers. It does serve a purpose, have a useful meaning, and is being used as though it is accepted already, so it must be a 'real word' .