Dirty money? Check your wallet

What's filthy and stays in your wallet?

If you thought dirty money was only found in offshore bank accounts, check your wallet instead. But you may want to wash your hands afterward.

Almost 60% of Europeans believe cash is the dirtiest item they come into contact with, ahead of escalator handrails, buttons on payment terminals and library books, according to a survey of 1,000 people released on March 25 by Mastercard.

A further 83% of the respondents, taken from 15 countries across Europe, believe cash carries a lot of bacteria. And they are right.

Independent tests on European money conducted by a team of scientists at Oxford University in December 2012, revealed that the average banknote contains 26,000 bacteria, enough germs to make you feel nauseous, and possibly even spread disease.

"Europeans' perceptions of dirty cash are not without reason," Ian Thompson, the professor from Oxford University who tested the cash, said in a news release. "The bank notes we tested harbored an average of 26,000 bacteria, which, for a number of pathogenic organisms, is sufficient for passing on infection."

Even the newest, and therefore cleanest, notes tested contained 2,400 bacteria, with Swiss Francs and Danish Krone the dirtiest money of all.

"(The bacteria) comes from multiple hands," Hany Fam from Mastercard told CNN's Richard Quest. "These notes have a long time in circulation, they're handed, hand to hand, from different individuals and it's inevitable that germs accumulate on them."

Clearly, a credit card company like MasterCard has its own economic interests in pushing people away from cash.

"No, I'm not just advocating credit cards: I'm just saying that consumers are increasingly flocking to other forms of payment -- not only for cleanliness, obviously, but for ease, for convenience, for lots of reasons," Mastercard's Fam said.

Still, cash is dirty. A 2002 study published in the Southern Medical Journal also found bacteria-laden banknotes. Over 80% of cash tested carried germs that could be harmful to people with lowered immunity. Seven percent of bills showed traces of bacteria that can cause serious illness, including Staphylococcus aureus and Klebsiella pneumonia, according to the study. Only 7% of the bills were germ-free.

Another study conducted in 2008 at Switzerland's University Hospitals of Geneva found that some flu virus cells could last for up to 17 days on Swiss banknotes, according to SmartMoney.com

So what to do? To prevent infection, scientists suggest basic hygiene: Keep your hands away from your eyes, nose and mouth, and wash your hands often.

But that won't necessarily prevent illicit banknote contamination.

Last year three employees at a Michigan Circle K store became ill after handling money that had been contaminated with methamphetamine residue, according to a local news website, Ann Arbor.com.

Cocaine is also a common contaminate in the U.S. A 2009 study conducted by the University of Massachusetts Dartmouth found up to 90% of paper money circulating in America contained traces of cocaine.