How Clean Is Your Money?

Has your mother ever told you not to stick money in your mouth, because "you don't know where that's been!" Have you ever really thought about where money's been and what's on it? Well let's think about it for short time. Cashflow trades hands all the time, and certainly can trade hands many times in one day. People from all over the world could possibly have touched the dollars and change in your pocket. If you take out hygiene customs from culture to culture or even from our own, then consider the sick who have touched your money before you acquired it. Starting to feel a little queasy yet?

There have been several studies to look at what exactly is on money and why it's there. Back in 1905, Dr. Thomas Darlington (the Health Commissioner of New York City) made a report and claimed that dirty money should be removed from circulation for the purpose of public health. The Federal Reserve itself does a test on bills it receives. The average lifespan of a paper US bill is about 18 months, but depending on its cleanliness will determine if it lasts longer or shorter. When a bill goes back into the Federal Reserve, it gets tested on a scale of 0-16. New bills receive a score of 16. Any returning bill that receives a score of less than 12 will be shredded. The Reserve calls a bill's dirtiness the "soil content". This test only tests if something is on the bill, but it won't say what is on the bill. That takes science teams and researchers.

In 1972, the Journal of the American Medical Association found that there were some harmful germs on money. They acquired 200 dollars and coins, and found things like fecal bacteria and Staphylococcus aureus on 13% of coins and 42% of the dollars. The University of San Francisco conducted their own test by obtaining coins and dollars from restaurants, vendors, newsstands, and post offices, and found that of the 113 examples, 18% of the coins and 7% of the bills had things like E. coli and Staphylococcus aureus.

The good news? Most viruses don't penetrate the skin, so unless you have a cut, then if they are on your hands alone, then you probably won't get sick. This is why washing your hands is so important with money. Once you rub your nose, mouth, or eyes, then the germs come into contact with tissue that can help facilitate the virus. But if you wash your hands first, then your likelihood of sickness is dramatically reduced.

There was another study conducted about the "soil content" from country to country, and it found that poorer nations had much more soil content than richer nations. The findings are still disputed because some claim the reason for this is basic hygiene practices of the countries, but others say it has to do with the economic state of the countries.

The other major factor in determining a bill's cleanliness is how well bacteria can colonize on money, and what that means, basically, is what is the dollar made of. Dollars that have many folds and creases (which is also a good indication of how old the bill is) is more susceptible to having colonies of bacterium growing. The University of Ballarat in Australia concluded in a study that the printing material in money is responsible for most of why money is dirty. For example, a British pound note is more likely to have bacteria than Australia's bills. Why? Because Britain uses cotton fibers for their money, which is much more fibrous and filled with holes for the bacteria to grow; whereas the Australian dollar is a polymer-based currency, and it is much more flat and harder for bacteria to gain a foothold. This isn't to say that all Australian currency is clean and Britain's is all dirty, but studies claim that with cotton-based currency, the bacteria have a longer chance of breeding and colonizing than on polymer-based currency.


Close up of British cotton-based currency



Close up of Australia's polymer-based currency

 But wait, that's not all that's on the money! There has been yet another study in regards to currency and Bisphenol A (BPA), which is a industrial chemical that's been used in containers since the 1960's. Studies on BPA to human contact has been primarily with regard to food; however, BPA is showing up on money. BPA is toxic, and presents health risks to people if consumed. So, why is it on currency? It's from receipts. Many receipts have BPA in the ink on receipt paper, and the BPA rubs off onto money, which then comes into contact with people. In a small study from 2010, 22 bills were tested, and 21 of them had traces of BPA on them. It's yet another thing to think about when handling money!

This is an ever-changing research project for many people all across the world. It'll be interesting to see what changes are made to money to help keep it clean. One method that many people call for is the end of physical money and to go exclusively to electronic funds. We'll see what happens!

And one more note of expendablenlightenment: in Japan, there are "clean ATMs". These are ATMs just like anywhere else, but the difference is that the yen is rolled between rollers for 1/10 of a second at a temperature of 392°F to kill off any bacteria.

Bet you didn't know that!