By: Eva Frederick

Over the past month or so, news outlets have published a flurry of articles that presumably struck fear into the hearts of cocktail aficionados everywhere: According to a recent release by Iowa’s Alcoholic Beverages Division, the iconic Moscow Mule could cause food poisoning.

It’s not the popular cocktail itself, which is made with ginger beer, vodka, and lime, that the report says is the culprit — it’s the cute mugs the drink is often served in. Traditionally, Moscow Mules are served in handled copper cups, a common sight on many an Instagram feed. The problem, according to the release, is that the acidity of Moscow Mules may cause the copper of the mug to leach into the drink, an occurrence that could, under some circumstances, cause copper poisoning.

While copper poisoning is no joke — the condition can cause symptoms such as gastrointestinal distress, vomiting and jaunidice — some sources suspect that the news frenzy caused by the release may be overexaggerating the dangers cocktail drinkers face as they sip their mules from copper mugs. The following paragraphs will lay out the facts, and discuss whether the threat of copper poisoning from Moscow Mules is really a cause for concern.

First, Iowa’s advisory bulletin was not based on an outbreak of food poisoning caused by Moscow Mules — it’s main purpose was to serve to reiterate a section of the US Food and Drug Administration Food Code regarding serving drinks in copper cups, the background being the trendiness of the copper-mugged cocktails.

“The recent popularity of Moscow Mules, an alcoholic cocktail typically served in a copper mug, has led to inquiries regarding the safe use of copper mugs and this beverage,” said the release. “The use of copper and copper alloys as a food contact surface is limited in Iowa.”

The FDA’s Food Code is a hefty manual of advice published every four years or so that aims to provide the guidelines needed for state and local governments to set up their own system of rules regarding food safety. Some states, as per the FDA’s advice, attempt to follow the Food Code in its entirety. Iowa is one of these states. Others pick and choose as they create their own set of guidelines.

Here’s what the Food Code has to say about copper: “Copper and copper alloys such as brass may not be used in contact with a food that has a pH below 6 such as vinegar, fruit juice, or wine.”

Moscow Mules, thanks to their lime-juice-heavy recipes, do indeed fall below the 6.0 pH mark, and so according to the Food Code they ought not to be served in copper mugs. But before you abandon the drinks entirely, take a look at some of the other factors at play.

The oft-cited rumor-busting website Snopes published a report on the rumors, deeming the news frenzy a mixture of true and false information. The true part? Yes, the acidity of the cocktail could cause the copper to leach into the drink. However, it is unclear just how long the cocktail would have to sit in the mug for the leaching to occur in any substantial quantity.

Copper is a trace element that occurs naturally in water and some foods. It becomes toxic at a certain level, which has been reached in the past when water sits for too long in copper-lined pipes, or when food containing a small amount of copper is eaten in excess. According to this report, scientists do not have a reliable method to measure accumulation of copper in the body, and therefore rely on external symptoms, which may only be seen at high concentrations of copper.

According to a 1999 study, some patients start showing signs of copper toxicity after drinking water with a dissolved copper concentration of above 3 mg per liter. No studies have specifically shown the rate at which copper might dissolve into a Moscow Mule from the walls of a cup, but Marc Solioz, a microbiologist Snopes interviewed who has experience with copper toxicity, said your drink would start to taste displeasingly metallic long before it reached that level of concentration. He speculated that the drink would have to remain in the cup for quite a bit longer than the amount of time it generally takes to drink a cocktail for substantial copper dissolution to occur.

In this case, common sense is key: if you come back to your table after a stint on the dance floor to find your drink doesn’t taste quite right, definitely stop drinking it. And before you order a mule at a restaurant, consider asking whether it is served in a copper cup.

Although the rumors may have been blown out of proportion, a little caution (and complying with the FDA’s Food Code) can’t hurt. Copper poisoning is a serious concern, and in severe cases can cause life-threatening complications such as cirrhosis of the liver, damage to other organs such as the kidneys and the brain, and falling into a comatose state. Copper poisoning can also lead to death.

Also, some people such as those suffering from Wilson disease, could be more affected by even a tiny amount of copper. Wilson disease causes copper to be stored in the body in excess, and therefore Wilson patients are more likely to suffer copper toxicity from a small amount of the element. Because of these risks and conditions, it is important to abide by the FDA Food Code and make sure you are being safe with your use of copper in cooking or food preparation. For more information on the FDA’s regulations on copper, you can read the entire food code here.

Thankfully, there are ways to enjoy your Moscow Mules free from even the slightest risk of copper poisoning, and keep the cute mug too. In the Iowa bulletin, the Alcoholic Beverages Divsion offered this advice: “Copper mugs lined on the interior with another metal, such as nickel or stainless steel, are allowed to be used and are widely available.” Cheers!