Pile of crumpled one hundred-dollar bills on the ground.

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On a weekend shopper’s “honey do” checklist, handling contaminated currency and getting sick in the process likely didn’t make the top of the list.

Yet that’s exactly what can happen, scientists say, when you get a grip on grimy dollars, coins, and germ-laden bank credit and debit cards.

That’s the takeaway from a new study that shows the actual spending currency consumers carry are so loaded with germs, they could be a threat to the consumer’s health.

The report from LendEDU has some interesting science behind it.

“To get some concrete evidence behind how dirty our various forms of payment are, (we) used a scientific device that tests for bacteria on a given surface; in this case, the tested surfaces were credit and debit cards and various bill and coin denominations,” LendEDU states.

That device calculates a “germ score” where the higher the number, the dirtier the surface and vice versa. As a frame of reference, restaurant and bar counter surfaces “should have a germ score of 10 or less to be considered sanitary,” LendEDU notes.

Suffice to say, the currency germ scores ranked significantly higher, and you can bet your bottom-of-the-barrel dollar on that. This from the study:

  • Credit and debit cards ended up being the dirtiest with an average germ-score of 285, followed by cash (160), and coins (136).
  • The dirtiest card LendEDU tested had a germ-score of 1,206, which is dirtier than anything the company tested for the study, including a NYC park bench, CitiBike bar handles, and an NYC parking meter.
  • On average, $5 dollar bills were encrusted with the most grit and grime – the study gave the bill a germ-score of 216.
  • The dirtiest bill that LendEDU found was a 2009 $20 bill, which earned a slime score of 633.
  • Coins came out the cleanest, with an average germ score of 136, although dimes were reportedly grimier than any other primary U.S. coin.

People who do “clean” for a living say it really isn’t surprising that our currencies and cards are so germ-laden — and it’s really the handler’s fault.

“According to research from Mastercard and the University of Oxford, the average banknote is home to 26,000 types of bacteria including E. Coli,” says Sean Perry, founder of Neat Services, a London-based cleaning company. “And the average coin has more germs than on a toilet seat.”

“It’s perhaps not surprising given the number of people that exchange money on any given day, many of whom do not wash their hands before or after handling it.”

Why so dirty?

Ask a germ studies professional and you’ll find that bacteria and money team up more than you may think.

“The typical sorts of germs you find on cash and cards are going to be the same kinds we find on door handles,” says Alex Berezow, a Ph.D. microbiologist at the American Council on Science and Health.

The actual reason cash is so contaminated is because human skin has loads of bacteria, Berezow says.

“For the most part, unless you’re immunocompromised, these sorts of “germs” are easily handled by our immune systems,” he says. “Of course, cash and other public objects can also spread things like cold viruses and influenza.”

The bottom line for consumers worried about dirty money is simple, Berezow says. “Wash your hands after handling money, especially before you eat or touch your face,” he says. “Otherwise, don’t worry about it.”

David Baldocchi uses his credit card to pay for gas at a Union 76 gas stationDavid Baldocchi uses his credit card to pay for gas at a Union 76 gas station
Photo by Justin Sullivan/Getty Images

Blow by blow: other contaminants found on money

Regular germs aren’t the only nasty elements found on financial cards and currency – in fact, germs may look better once you know what else is on that $5 bill.

“There’s quite a lot that can be found on cash,” says Nikola Djordjevic, a physician with MedAlertHelp.org. “For example, cocaine can be found on money. Drug dealers often use their drug covered hands to move cash. And drug users also use rolled up cash as a sniffing straw.”

It gets worse, Djordjevic says. “Even fecal matter can be found on the bills,” he adds. In fact, the money we carry every day is dirtier than the insides of our toilets.”

There is some good news, however, on all that bacterial transmission. “Even though this might sound pretty scary, paper money is not so good transmitting diseases,” he says. “Even though the material used to make paper currencies is a good environment for germs to land, the temperature and moisture levels are not typically compatible to allow microbes to proliferate.”

Like Berezow, Djordjevic says there’s not much you can do to cleanse yourself from paper currencies and plastic bank cards, other than omitting them altogether.

“It would be pointless to wash all the money you have and rewash it every time you get change or receive a bill,” he says. “To keep your health in check, just wash your hands as regularly as you can and use e-banking payments whenever you can.”

Disgusted consumers are catching on — and letting go

U.S. consumers, especially those who live in large urban centers, have had enough with “dirt, filthy, stinky, diseased money,” as one Californian puts it.

“Cash is disgusting,” says Dan Hall, a resident of Los Angeles, Cal. “In Los Angeles, our money is filthy. We have homeless people everywhere, they accept change from people, and recirculate it into society. Cash is absolutely dirty and we touch it every day.”

According to Hall, more and more L.A. businesses now are getting rid of cash.

“I went to Bluestone Lane Cafe in Los Angeles, and it was the first time I saw a place that would not accept cash at all, although I found it rather ironic that they wouldn’t let me spend cash, but had a tip jar,” he says. “This is more and more common and many countries, cash will be obsolete by 2030.”

For example, Sweden is almost entirely cashless, and with new technologies like finger chips and facial recognition technology, cash use might well be in a consumer’s rear view mirror.

“This will be healthier for everyone,” Hall says. “The U.S. Center for Disease Control has even said that Hepatitis A can be spread via money. That’s why I started using my ApplePay, and that works in most places.”

“Soon cards and cash will be a thing of the past and we will be buying biscotti’s with bitcoin.”