Moscow Mule Copper Cups Could Trigger Food Poisoning

The Alcoholic Beverages Division has a warning for fans of Moscow Mule cocktails – specifically ones served in copper cups: They could lead to food poisoning.

States adhere to the Food and Drug Administration’s Model Food Code. This code bans “copper from coming into direct contact with foods that have a pH below 6.0,” according to the Alcoholic Beverages Division, which published this warning late last month. These foods include vinegar, fruit juice and wine, as well as the ingredients of a classic Moscow Mule.

Though people shouldn’t use copper mugs with a copper interior when drinking Moscow Mules, they can enjoy these drinks in copper mugs with a different metal-lined interior, such as nickel or stainless steel.

In large amounts, copper can be poisonous. Breaking down the science further: “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,” according to the Alcoholic Beverages Division. “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.”

CBS News points out Moscow Mules have grown in popularity, as people often choose to show off their drinks in pictures posted to social media.