Eco-aware coffee drinkers run the risk of being exposed to potentially harmful bacteria if they don’t wash their reusable cups shortly after use, a study has revealed.
Research carried out by Aston University has shown cups left unwashed until prior to the next use pose a greater risk than those rinsed or cleaned shortly after a drink is finished.
Reusable coffee cups have grown in popularity amid suggestions the government could introduce a “latte levy” to reduce the waste created by 2.5 billion disposable coffee cups each year.
The Aston University study saw people use their coffee cups in a number of different ways over a week, from rinsing it immediately after finishing their drink to leaving the remains of the coffee in the cup and then washing it before the next use.
Professor Anthony Hilton, Deputy Executive Dean of Life & Health Sciences at Aston University, said: “Drink residues left in reusable cups are a good source of nutrients for bacteria which can multiply rapidly during storage.
“If the cup is refilled without appropriate cleaning, these bacteria can represent a significant source of contamination.
“Consumers should be mindful of reusable cup hygiene and clean them in the same way they would any other food contact surface.
“This can be easily overlooked and it can be difficult when washing facilities are not readily available following cup use and reuse, particularly when using the cup while travelling, but it is important.”
The study has led to calls for reusable cups to carry anti-microbial product protection to reduce the presence of bacteria, regardless of the frequency and timing of washing.
Paul Morris, CEO of Addmaster said: “The evidence from the study is clear. To have effective hygienic use in a normal reusable coffee cup, you have to wash your cup shortly after use.
But the very nature of a reusable cup means people could be using it while they are on the move with no chance to rinse or wash it immediately after use.
With that in mind, we need to look at methods to reduce the risk, and one way is for manufacturers of reusable cups to incorporate anti-microbial technology in their products, such as Biomaster product protection.”
Simon Ellin, chief executive of The Recycling Association, welcomed the findings and the increased use of reusable coffee cups - but urged people to be wary about the hygiene risks.
He said: “We welcome the public’s desire to reuse items such as coffee cups but would want them to do so with caution and make sure they wash their cups thoroughly and, if possible, choose one with anti-microbial product protection.”