I’ve always read that floral wires are a no-no because the wire is not food safe. I assume toothpicks are food safe because they are always used for h’ordervers and stuff. I’ve never had a problem. Another tecnique I’ve read, which will help also keep floral wires or toothpicks from directly contacting the cake is to insert straws into the cake and then insert the wire or toothpick in there. But then you are sticking straws in the cake which could also introduce bacteria… I use large bubble straws as my support between tiers and this is a techinque used by many so I can only assume and hope it is safe too.