Baghouse Dye that is approved for indirect food contact

Does anyone have any suggestions for a baghouse dye product that is approved for indirect food contact?  

Is there any regulatory/GFSI requirement regarding this? Why should it need an approval if it's indirect food contact?

I guess I should restate...there is a possibility for trace amounts to contact food product.  We do cleanouts but I would prefer to use a dye that is approved for incidental food contact (like food grade grease).