Research that was carried out by students and faculty at Carroll College and published in a national journal discovered that the copper cup traditionally used to serve the popular drink could leach copper into the drink beyond federal standards.

Nine students and two faculty members graced the cover of the January/February issue of Environmental Health magazine with their research titled “Quantifying the rate at which copper leaches from a copper drinking vessel into beverages simulated under consumer use conditions”.

Caroline R. Pharr and John G. Rowley, both associate professors of chemistry at Carroll, led the project which involved chemistry students.

The research found that copper leaching into the beverage was significant and exceeded US Environmental Protection Agency standards of 1.3 parts per million for drinking water within 27 minutes at room temperature. They also note that the problem can be alleviated by serving the Moscow Mule in a copper cup lined with stainless steel to avoid direct contact of the acidic liquid with the copper surface, as stipulated by the Food and Drug Administration.

The Moscow Mule, which contains ginger beer, lime juice and vodka, was listed on thrillist.com in 2018 as the most popular cocktail not only in Montana, a state rich in copper history, but also in Michigan, Nebraska, New Mexico and New York. This list was compiled using Google search data.

The idea for the Carroll College research came about when someone at Pharr was drinking from a Moscow mule and asked about the potential dangers of sipping from the copper cup.

“I thought we could look into that,” Pharr said Friday.

She later said it seemed like a simple question, “but it was really cool chemistry.”

Rowley and Pharr said that although there have been warnings about Moscow mules and copper cups in the past, Carroll’s study, which lasted around two years, is the first to offer quantitative figures . And, for the first time, it provides hard numbers for the public to make an assessment.

Their article states that according to the World Health Organization, a safe intake of copper is 10 milligrams per day. A person would need to drink 30 Moscow mules in 24 hours to reach this number.

“Given this information, acute copper toxicity from consumption of Moscow Mules in a single sitting is unlikely,” they wrote.

For the purposes of the study, the vodka was replaced with 200 proof ethanol diluted to the appropriate concentration.

“We quantified copper concentration using inductively coupled plasma atomic emission spectroscopy (ICP-AES),” they wrote. “The leaching rate of copper in the Moscow Mule cocktail was found to be significant, and the concentration of accumulated copper exceeds U.S. Environmental Protection Agency standards for drinking water in 27 minutes (World Health Organization Health, 2004),” they wrote.

The Carroll team said the Journal of Environmental Health article provides “an intriguing and relevant example for environmental health professionals and the public of a potentially hazardous substance that is common and at the same time extremely easy to avoid.” .

“Our study presents a clear alternative for environmental health professionals and the public, as fortunately copper cups lined with stainless steel or other chemically inert materials are widely available for similar cost,” they wrote. .

The newspaper notes that there is “a lot of knowledge” about why the drink is served in a copper cup, adding that some people claim the taste is “enhanced by a copper vessel”.

The problem arose elsewhere. In 2017, the state of Iowa announced that it had adopted the Federal Food and Drug Administration’s Model Food Code, which prohibits direct contact of copper with foods with a pH below 6.0. The pH level is a measure of the acidity/basicity of water.

“The pH of a traditional Moscow Mule is well below 6.0. This means that copper mugs that have a copper interior cannot be used with this drink,” the alcoholic beverages division of the State of Iowa as of July 2017. “However, cups made of copper lined inside with another metal, such as nickel or stainless steel, are permitted for use and are widely available.

A Montana bar, liquor store and copper mug seller contacted for this story could not immediately be reached or declined to comment for this story. However, the Montana Tavern Association posted a photo of the cover of the environmental health article on its Facebook page, with a link to the story, under the words “Uh-oh!”

Carroll students who have participated include Dain Adams, Isabelle Gray, Erin Hanson, Gunnar Hilborn, Victoria Kong, Emma Patello, Stephen Schmidt, Dimtry Shulga and Monika Weber.

Weber, a 2017 graduate and co-author, said in a press release that she felt lucky to have worked on the project.

“The skills and experience I gained through the chemistry program made me the chemist I am today and allowed me to excel in my current role as a chemist in a chemical analysis laboratory. metals,” she said.

Rowley said Carroll is unique in that it provides research experience for students and enables mentoring of undergraduate students to solve real-world problems.

John Cech, president of Carroll College, said the project is an example of Carroll’s motto “Not for school, but for life”.

“This commitment to providing transformative student experiences gives our graduates a distinct advantage when applying for the competitive pre-professional programs they enter after graduating from Carroll College,” he said, adding that the college has a 80% acceptance rate in medical schools and 100% acceptance rate in graduate schools of chemistry.