The Moscow mule is popularly served in a copper mug, which takes on the cold temperature of the liquid. Some public health advisories recommend copper mugs be plated with nickel or stainless
steel on the inside and the lip, but it has been disputed whether the time and acidity involved in the drinking of a Moscow mule would be enough to leach out the 30 milligrams of copper per litre
needed to cause copper toxicity.
