DENVER -- Moscow Mules are traditionally served in a copper mug, but health officials warn the classic combination could lead to food poisoning.
The Iowa Alcoholic Beverages Division recently issued an advisory bulletin to establishments that sell and serve alcoholic beverages, warning them not to use copper mugs.
Officials stated that using copper mugs to serve beverages with a pH balance below 6.0 could cause copper to leach into the drink.
The pH of a traditional Moscow Mule -- which is made with vodka, ginger beer and lime juice -- is well below 6.0, according to the bulletin.
Other examples of beverages with a pH below 6.0 include fruit juice and wine.
"When copper and copper alloy surfaces contact acidic foods, copper may be leached into the food," health officials stated. "High concentrations of copper are poisonous and have caused foodborne illness."
Health officials said establishments in Iowa can no longer use the signature copper mug to serve the cocktail unless they are lined with another material.
"Mugs that have a copper interior may not be used with this beverage. However, copper mugs lined on the interior with another metal, such as nickel or stainless steel, are allowed to be used and are widely available," officials said.
According to the U.S. National Library of Medicine, consuming large amounts of copper can cause abdominal pain, diarrhea, vomiting and yellow skin (jaundice).