Firstly, if a drug is not approved, this does not mean it is or is not a hazard. It really means there has been no determination made as to it's safety. This is usually because there is no viable commercial reason to test it. (It is used primarily by small flock owners, or tomato gardners.... it is not in the food chain etc...) But even beyond that... why would you even consider giving an animal that produces food, (not is food, that is different but probably not much) any of these chemicals, if as some say, once you do so, you can no longer utilize them in their purpose. If it is so toxic, that you might have an issue second hand through an egg and after a assumed waiting period, you would think it would be so toxic it killed the subject. The fact is, that after a waiting period of a few days, the level of these chemicals is well below what would be considered a hazard (in the event you can even find data supporting what a hazardous level would be). I note a lot of confusion already. That is one good reason to use the older chemicals. They may not have been proven or tested, but they have been tested over the years by usage and experience, and are probably considerably better documented than the newer so called "approved" products.