What Harmful Microbes Are Living On Your Cash?

They say that money makes the world go around, but it turns out that it may also serve as a vehicle for harmful, disease-causing bacteria.

A recent article published in Scientific American takes a closer look at past studies that have found out just how dirty the money that we handle on an everyday basis really is. These studies found that our cash may be inhabited by a number of concerning bacteria as well as other harmful pathogens, pathogens that can easily put our health at risk.

The composition of currency in the United States is a contributing factor, and, as it turns out, banknotes are even more hospitable to bacteria than coins. According to the article, “The fibrous surfaces of US currency provide ample crevices for bacteria to make themselves at home.” US banknotes are comprised of cotton (75%) and linen (25%), which might make the notes more welcoming to harmful bacteria. Other countries such as Australia and Canada use banknotes that are polymer-based, which are thought to be “cleaner” or have greater resistance when it comes to dirt or bacteria collection.

In addition to composition, the amount of time that currency remains in circulation is also important; the longer it is circulated, the more hands it touches, and the more of a chance it has of being contaminated. Since lower-denomination bills—ones, fives, tens—tend to be used more often, studies suggest that these bills have an increased likelihood of being contaminated with harmful pathogens. These pathogens can survive on currency for a number of months and currency can circulate across the US in a wide window ranging from four to 15 years, with coins potentially circulating for a whopping 25 years.

Although some microbes are not harmful, a number of them can result in sickness. Past studies have found a number of harmful bacteria on circulating US currency. In fact, cultures taken from random samples in a study dating back to the 1970s found that 13% of coins and 42% of paper currency were contaminated with harmful pathogens. Antibiotic-resistant Staphylococcus aureus, Escherichia coli, and Pseudonomnas aeruginosa are among the harmful pathogens that have been found on US currency in the past. In addition, drugs such as cocaine and heroin as well as yeast and fungi have also been found. In 2010, researchers in Australia sought to identify the “actual number of bacteria per square centimeter” on a number of banknotes. They found that a US banknote contains “10 such microbes per square centimeter,” which proved to be a higher amount than the microbes found on currency from Australia or New Zealand.

In addition, a study conducted by the US Air Force back in 2002 found pathogenic organisms on 94% of one-dollar bills that had been collected in Ohio. According to the study, “These results suggest a high rate of bacterial contamination of one-dollar bills.” Some of the organisms that were noted were bacteria capable of causing pneumonia or a number of other serious infections; this finding piggybacks off of the notion that smaller bills may house even more bacteria than their larger counterparts.

Additional studies have found that factors such as humidity, moisture, or mucus can result in the persistence of harmful microbes, flu viruses among them. In 2008, Swiss researchers found that on average, flu viruses could persist on Swiss francs for one or two days. However, if accompanied by mucus, the virus could survive for 17 days.

In ongoing research over the last few years, Julia Maritz, a New York University graduate student, accompanied by her colleagues at NYU’s Center for the Genomics and Systems Biology, have taken a closer look at material on 80 $1 bills. Their results are particularly concerning; they found around 3,000 different organisms on the banknote samples and these organisms included bacteria “linked to pneumonia, food poisoning, and staph infections.” In addition, the researchers also discovered DNA from a number of animals. Martiz said, “Our research is focused on the presence of these [microscopic] organisms. We don’t work on the transmissibility aspects. We don’t know if these organisms are making people sick—it’s not something you can tell from the type of data we generate.” The research is ongoing and has not yet been published, however, the work has been covered by The Wall Street Journal.

The consideration of a potentially cashless society has been suggested in order to decrease these risks but will individuals feel comfortable having every single financial transaction recorded in an age where computer hacking seems to be more and more commonplace? It is already recommended by healthcare professionals and researchers alike that individuals consistently wash their hands throughout the day, especially before a meal, but is that enough to prevent the transmission of potentially harmful pathogens? If you consider this information, it can’t hurt.