Whether it’s premium gin infused with vintage Harley-Davidson parts or finding out that drinking might actually improve your memory, there’s always something crazy and new making the rounds in the alcoholic beverage industry—and normally that’s a good thing.
But the craziest thing we heard concerning cocktails this week is definitely not good news. Unfortunately, it’s got everything to do with one of the most popular and tastiest beverages on the bar menu: the Moscow Mule.
The Food and Drug Administration’s Model Food Code actually "prohibits copper from coming into direct contact with foods that have a pH below 6.0. Examples of foods with a pH below 6.0 include vinegar, fruit juice, or wine"—and a Moscow Mule would definitely fail that test, according to the advisory. All three ingredients in a Moscow Mule can be acidic: vodka (which can have a pH as low as 4), lime juice (commonly around 2.0–2.4), and ginger beer (which is fermented with lemon, so it is typically less than a neutral 7.0 pH).
When the acidic drink hits an exposed copper cup, the drink can react with the copper, leaching the metal into the booze and…well, you get the idea. Everyone needs a tiny bit of copper to survive; too much, though, is straight-up poisonous. (Of note: While brewers use copper to make beer, "the levels of copper necessary for successful beer fermentation (i.e., below 0.2 mg/L) do not reach a level that would be toxic to humans," the advisory says.)
That doesn’t mean you need to quit drinking the boozy beverage altogether, though. You just need to make sure that the interior of your copper mug is lined with another metal like nickel or stainless steel, says the advisory.
So double check your mug, and mix yourself a Moscow Mule. Even if you have that stainless steel cup, though, just don’t overdo it—drinking too much could damage that set of six-pack abs you’ve been working on all summer and even wreak havoc on your heart health.