I'm almost finished with my coop and am searching for food grade DE. I called two local feed stores and asked if they carried it. Both stores said they have "Feed Grade" DE. The clerk said that people use it in cattle feed (although it's not legal to) but it wasn't for human consumption. I did a search on here for feed grade DE but couldn't find anything. So I'm thinking that it is NOT safe for my chickens. Would I be correct?