You are able to remember that the prefix non- usually means “not” by means of the word nonpoisonous, for a material that's nonpoisonous is “not” toxic. Being an interjection to negate what was mentioned prior to or expose it as sarcasm, it can be attested by 1900, popularized 1989 by https://remingtonhnsxc.ourabilitywiki.com/9175760/the_definitive_guide_to_papiertaschen