Copper changes form when it’s combined with acidic solutions, she said, which means it loses it’s metallic makeup and transforms into copper(II) or copper(I).
“Copper(I) is known to be very toxic,” Andrews explained. “But humans need copper(II) in some small amount in order to survive in their regular biochemical functions. Actually we have enzymes in our body that are part of our regular biological processes that have copper(II) as part of their chemical structure.”
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Therefore, the concern should not be the copper mugs, researchers said, but how long the Moscow Mule sits in them.
In order for copper to cause symptoms of poisoning, studies show there has to be a concentration of 30 milligrams of it per liter.
“You have to let the copper mug sit in straight lime juice for a few hours before you can even start to begin to worry about copper poisoning,” Andrews said. “Based on the dissolution rates, it’s just nonsensical.”
That applies even if you nurse your cocktail all night or drink a liter of Moscow Mule from a copper mug. Andrews said you’re in the clear.
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