WORLDWIDE — Moscow mules are a popular, refreshing cocktail — one that even comes with its own signature cup.
Bad news: The copper mugs that they are traditionally served in may be bad for your health.
The Iowa Alcoholic Beverages Division has issued an advisory bulletin based on the Food and Drug Administration’s Model Food Code which “prohibits copper from coming into direct contact with foods that have a pH below 6.0.”
From the bulletin:
High concentrations of copper are poisonous and have caused foodborne illness. When copper and copper alloy surfaces contact acidic foods, copper may be leached into the food.
Carbon dioxide may be released into a water supply because of an ineffective or nonexistent backflow prevention device between a carbonator and copper plumbing components.
The acid that results from mixing water and carbon dioxide leaches copper from the plumbing components and the leachate is then transferred to beverages, causing copper poisoning.
Backflow prevention devices constructed of copper and copper alloys can cause, and have resulted in, the leaching of both copper and lead into carbonated beverages. Brass is an alloy of copper and zinc and contains lead which is used to combine the two elements.
Historically, brass has been used for items such as pumps, pipe fitting, and goblets. All 3 constituents are subject to leaching when they contact acidic foods, and food poisoning has resulted from such contact.
Foods with a pH below 6.0 include vinegar, fruit juice and wine, and since the drink is traditionally made using vodka, ginger beer and lime juice, it fails to meet that criteria.
All's not lost though. The Iowa Alcoholic Beverages Division clarified that “copper mugs lined on the interior with another metal, such as nickel or stainless steel, are allowed to be used and are widely available.”