DAVENPORT, Iowa -- Bars around Iowa are doing away with those shiny signature Moscow Mule mugs thanks to a recently adopted law.According to the state's alcoholic beverage division, the vodka-ginger beer-lime mixture cannot be served in a solid copper mug.Officials cite high concentrations of copper causing possible foodborne illness.In general, the law prohibits copper from coming in direct contact with foods that have a pH level below six. A traditional Moscow Mule falls well below that threshold.The state allows some copper mugs which have metal or stainless steel linings inside.