#Covid19 is not the only reason one should wash their hands regularly.
While more people are using credit cards, debit cards, and other forms of electronic payment to purchase goods and services than they did five years ago, money ... cash is still a frequently used payment method for Americans. Did you know that banknotes and coins harbor various microbes, including bacteria, viruses, protozoa, and fungi? The types and amounts of microbes found on these currencies can vary depending on factors such as how often they are handled and exchanged, the age of the money, how they are stored, and where they have been. One study identified viable microbes, typically those found on human skin and from oral sources, on the surface of the currency obtained from a New York bank. The most abundant microbes detected were eukaryotes, followed by bacteria, viruses, and archaea. 1
Some of the most commonly found microbes on U.S. currency include:
1. Staphylococcus aureus - a type of bacteria that can cause skin infections and respiratory
2. Escherichia coli - a type of bacteria that is found in the intestines of humans and animals
and can cause diarrhea and other gastrointestinal symptoms.
3. Influenza virus - a type of virus that can cause the flu.
4. Rhinovirus - a type of virus that can cause the common cold.
5. Fungi - various types of fungi, including Aspergillus and Penicillium, can cause respiratory
and other infections.
The lifespan of microbes on banknotes and coins can vary depending on factors such as the surface of the currency and the environmental conditions. Studies have shown that many microbes can adhere and persist on money for varying amounts of time. For example,
Staphylococcus aureus and Escherichia coli can survive on banknotes for up to 72 hours, while other types of bacteria, such as Salmonella, can survive for up to 24 hours. Influenza and rhinovirus can persist on banknotes and coins for several days or weeks under certain
U.S. currencies are made from various materials that impart certain surface characteristics that can significantly influence bacterial adherence and survival. U.S. banknotes are made of 75% cotton and 25% linen, giving them a unique raised and coarse texture and durability specially formulated to resist wear and tear and water damage. Due to the coarse and fibrous surface, banknotes have a strong adherence and survival for microbes.
U.S. #coins are made primarily of metals, with different combinations of metals used for
different denominations. For example, the penny is 97.5% zinc and 2.5% copper, while the
nickel is 75% copper and 25% nickel. The dime, quarter, and half-dollar coins are made of a combination of copper and nickel. Zinc, nickel, and copper are #metals commonly known for their antimicrobial properties; they inhibit the growth and survival of certain types of #bacteria and viruses. The smooth and inhospitable surface of the coins contributes to the poor adherence and low survival rate of microbes when compared to banknotes. Additionally, coins are less absorbent than paper bills, so they may not provide an environment conducive for microbes to grow and multiply. At the same time, paper banknotes are made of a fibrous material that can trap and retain moisture, creating a more hospitable environment for microbes to thrive. Furthermore, coins are typically handled and circulated less frequently than paper banknotes and thus have a longer lifespan because people tend to hold onto them for longer periods of time. As a result, coins may be exposed to fewer sources of contamination than paper banknotes. However, it should be noted that while coins may be toxic to bacteria, bacteria can adapt to their environment, which may explain the low levels of bacteria found on circulating coins.
Some countries'; currencies have antimicrobial properties incorporated into their design to help reduce the growth of microbes. For example, the new £5 and £10 notes in the UK are made of a polymer material with antimicrobial properties. Australian banknotes are made of a type of polymer, specifically a biaxially-oriented polypropylene (BOPP), which is a thin, flexible, and durable plastic film. Studies have suggested that Australian banknotes may be cleaner and have fewer microbes than other types of banknotes, such as U.S. banknotes, due to the smooth surface of the polymer banknotes, which may make it harder for microbes to cling to their surface and grow, compared to the more fibrous surface of paper banknotes. Additionally, some credit card companies and banks offer options for contactless payment, which can help reduce the risk of encountering microbes on credit cards.
While most people's immune systems can fight off any pathogen they encounter, it is still
important to practice good hygiene habits, such as washing your hands regularly after handling money or touching surfaces in public places, to minimize your risk of getting sick. As a side note, traces of cocaine have also been detected on banknotes due to drug dealers exchanging illicit drugs for money. This is an everyday occurrence in cities across the U.S. and another beneficial reason for handwashing after contact with money.
Finally, if you are concerned about the cleanliness of your money, you can always disinfect it using a safe wipe or spray for use on paper, metal, or plastic surfaces. You can also wipe your credit cards, debit cards, mobile phones, and other devices with a safe cleaning solution, such as a solution that contains between 60% and 90% isopropyl alcohol and 10 and 40% purified water (rubbing alcohol). Isopropyl alcohol is strongly effective at disinfecting against bacteria, fungi, and viruses, but once the alcohol content falls below 50%, its usefulness for disinfection drops sharply.
Dr. Bernine Khan / Dr. Annmarie Waite
1. Julia M. Maritz, Steven A. Sullivan, Robert J. Prill, Emre Aksoy, Paul Scheid, Jane M.
Carlton. Filthy lucre: A metagenomic pilot study of microbes found on circulating currency in
New York City. 2017. PLOS One.