You can keep in mind that the prefix non- implies “not” via the term nonpoisonous, for the substance that is definitely nonpoisonous is “not” poisonous. As an interjection to negate what was explained ahead of or expose it as sarcasm, it is attested by 1900, popularized 1989 by "Wayne's World" https://non87430.blogtov.com/7416690/woven-things-to-know-before-you-buy