With both convenience and cost-saving benefits, the popularity of reusable cups has skyrocketed recently, but there is a catch: Many people are reusing these cups without washing them between uses or are not washing them thoroughly enough to prevent the buildup of dangerous bacteria, particularly around the hard-to-clean mouthpiece section.
Factor in the sugar and milk many of us add to our coffees and an unwashed or insufficiently washed cup becomes a breeding ground for potentially deadly bacteria. A recent study conducted by researchers from Aston University in the U.K. has found a solution to the problem: reusable cups made from an antimicrobial material known as Biomaster. (Related: Drink responsibly: Are you aware of the environmental impact of single-use coffee cups?)
Why normal reusable cups are dangerous
As reported by the Telegraph, Public Health England recently issued a warning to consumers about using reusable cups that have not been properly cleaned, after research found that many office workers reuse these cups after a simple rinse or use them several times a day and then only wash them once.
"Consumers need to be aware that if a product is used more than once, there is a potential health risk if the drinking vessel has not been cleaned properly. …
"If the cup is dirty, hot water alone is not good enough -- you need detergent too -- and if it’s OK for your hands, it’s too cool to kill bacteria. The main danger will be from the mouthpiece which will have hard to reach areas that bacteria could grow in, so yes, some would be better than others," warns Paul Morris, director at packaging hygiene firm AddMaster.
But, even “proper” washing might not be enough. The Aston University research team discovered that even washing the cup in hot water with detergent after each use is not enough to prevent harmful bacteria from growing.
Washing standard reusable cups is not enough
The researchers compared the bacterial load on eight reusable cups that had been used and cleaned in a variety of ways to the amount of bacteria found on antimicrobial coffee cups.
This material uses silver technology and works in three different ways. When micro-organisms come into contact with the antimicrobial material, silver ions stop them growing, prevent them from producing energy and stop them replicating. In short, bacteria don’t stand a chance against this material.
Medical Xpress reported on how the study was conducted:
A range of usage profiles were investigated with samples from each tested over a period of five days:
- One coffee per day, washing the cup in hot water with detergent after use, with the cup left to dry naturally.
- One coffee per day, rinsing the cup under running cold water after use, with the cup left to dry naturally.
- One coffee per day, no cleaning of cup in between use. Coffee finished and left to dry naturally.
- One coffee per day, leaving 20ml of unconsumed coffee in the bottom of the cup which remained until next use, when the cup was emptied and rinsed with cold water prior to refill.
The result? All the conventional cups were found to contain high levels of dangerous bacteria – including the cups that were washed or rinsed. The antimicrobial cups were found to contain the lowest levels of bacteria overall.
"Bacteria can easily grow on the inner surfaces of a reusable coffee cup unless it is washed after use,” noted Anthony Hilton, a professor of applied microbiology with Aston University. “Antimicrobial technology built into the drinking vessel significantly reduces the opportunity for bacteria to grow.
"Our study shows that reusable coffee cups treated with antimicrobial technology are much less likely to become heavily contaminated with bacteria."
So, if you’re planning to grab a coffee and run out the door with it every morning you might want to consider switching to an antimicrobial cup.
Learn more about the environmental impact of single-use disposable cups at Environ.news.
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