Okay..."Codex" means it is approved by some consortium or other having to do with the United Nations I believe. It means NOTHING if your bag does not have the "Codex" word on it. What you need to be careful of is that there are manufacturers that make different kinds for different purposes. PermaGuard arguably, makes the best in my opinion and I sell it in smaller amounts. However, PermaGuard also makes a DE for external use on animals because it contains perethrins (sp) which is an external insectiside. Again, if your bag says to use 2% in feed, it is safe for you to use. Again, it does not have to have the word "codex" on it to be food grade. Hope this helps!