After analyzing the samples, the researchers found that the paper money actually contained a much greater variety of bacteria than any of the areas tested.
And it’s not just the harmless stuff, either: Thirty-six percent of all the bacteria were potentially pathogenic, meaning they could make you sick, the researchers say. That included E.coli and Clostridium difficile, two organisms which can cause diarrhea or even more serious illness.
The researchers also discovered that the percentage of antibiotic-resistant bacteria was also significantly higher on the banknotes than on any of the other samples.
“In short, banknotes act as a medium ‘absorbing’ bacteria from other environments, and the potential pathogens live quite well on the banknote surface,” study author Jun Li, Ph.D., said in a press release.
Paper money can get contaminated by bugs from the air or on a surface, but unhygienic behaviors from the handler—like not washing your hands after going to the bathroom, or coughing into your hands and then touching the bills—plays a big part, too. And that’s a big problem, since money changes hands frequently, allowing for a chain of possible transmission.
The best way you can stay protected is to wash your hands after touching the money—here’s how to do it the right way. And signing up for mobile or electronic payment options can greatly reduce your contact with physical bills, too.