The state of Iowa has issued a statement explaining the potential dangers of using the popular drinkware.

By Danica Lo
Updated August 04, 2017
Credit: Getty Images

The Moscow Mule is as synonymous with summer as it is visually distinctive—a cool, refreshing vodka and ginger beer cocktail housed in a traditional copper mug, which serves the function of being both beautiful and insulating, making sure your drink stays frosty cold for as long as possible. But could the days of copper mugs be numbered? If you believe the latest dispatch from Iowa's Alcoholic Beverages Division, perhaps. The state recently released a strongly-worded warning about the danger of pairing copper mugs with beverages that have a pH lower than 6.

"Iowa, as well as many other states, has adopted the federal 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," the bulletin explains. "Examples of foods with a pH below 6.0 include vinegar, fruit juice, or wine. The pH of a traditional Moscow Mule is well below 6.0. This means that copper 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."

While the FDA Model Food Code isn't a new one, it's only the recent resurgence in popularity of the Moscow Mule that's brought it to state officials' attention. Turns out, an acidic beverage dispensed from a copper container could be poisonous. Yup, you read that right: poisonous.

"High concentrations of copper are poisonous and have caused foodborne illness," the Alcoholic Beverages Division announcement explains. "When copper and copper allow surfaces contact acidic food, copper may be leached into the food."

Consume too much copper? Symptoms of copper poisoning could include: abdominal pain, diarrhea, vomiting, and jaundice. According to MedlinePlus from the U.S. National Library of Medicine, even handling large amounts of copper for a prolonged period of time could cause your hair to turn green. Longer-term exposure could lead to "lung inflammation and permanent scarring" which can, in turn, lead to "decreased lung function."