For a more esoteric and realistic scare, let me introduce you to Ethidium Bromide. The thing has as much toxicity as salt water with the amount they are used in a lab, but many places still treat it as high hazardous waste and demand specific procedures for handling and disposal.<p>Meanwhile, bleach is probably more toxic and carcinogenic than this thing but nobody say anything about special handling of pure concentrated bleach. Most scientists know EtBr is not too toxic but because of the administration and extra burdens of dealing with it to satisfy the rules made from outdated knowledge, they end up switching to something else.