The dollar is the world's greatest tourist. It leaves the dank comfort of the wallet and rides the hand express by the hour, passing through millions of hands and visiting cities all around the world.

Whether it's a plush hotel lounge or malodorous fishmonger's stall, the dollar is an undiscerning traveler. In certain more hedonistic cultures, the dollar's even spent a good amount of time stuffed halfway up a nose. So it should come as no surprise that the dollar is by far one of the filthiest things in the world.

Whether we like to think about it or not, money is dirty - and there ain't any need for crime or the Russian mafia to prove this point. The germs are sitting right there in your hands.

Some studies have shown that paper money can host bacteria that commonly infect hospital patients or people with depressed immune systems. In 1972, a study in the Journal of the American Medical Association cultured bacteria from 200 coins and bills and found offensive germs like faecal bacteria (or faecal coliforms) and Staphylococcus Aureus on 13 percent of coins and 42 percent of notes.

Coliforms are found in faeces and these can contain germs like E. Coli, which can cause food poisoning symptoms and in severe cases, even death. Other germs like Pseudamonis can cause skin infections and Streptococcus can cause sore throats and blood poisoning.

One dollar, millions of germs

Indeed, researchers have found that dollar bills are very much contaminated with a multitude of organisms, certainly dirty enough to give the term "money laundering" a whole new meaning.

Last year, researchers at City University in Dublin, Ireland announced that 100 per cent of the bank notes that they had studied carried trace amounts of cocaine. Just a month before, a study suggested that 94 per cent of banknotes in Spain were similarly contaminated.

While the findings might suggest that too many of the Irish and Spanish love their white powder, it?s a more telling indicator of just how easily germs and other undesirable, minute organisms are spread through banknotes and coins. Once you think about it, it is hard to get the dirty thought out of your mind.

Because the truth of the matter is that dollar bills move through our society - and sometimes out and cross continents to others - as easily as common germs mingling in the air. They are conveyors of microbes, and are much more mobile in transmitting infections than any other contaminated object you can think of.

"I get really freaked out when I think about the number of germs that must live on money," admits 41-year-old Katrina Karim. The public relations consultant is especially mindful of money that changes hands in "high turnover" places like in taxis and hawker centres.

"It's just that I notice more and more these days that people generally don't wash their hands after they use the toilet, so even things like the TV remote control in hotel rooms and door handles scare me!"

Lee Yung-Ming, a 38-year-old business development manager has a friend with a phobia of escalator hand rails. "It all started when she saw someone wiping some mucus on a handrail - it got her imagination going and these days, she never so much as touches a handrail in public. And she never leans on lift walls.

Mr Lee admits that he does think about the potential foulness of the dollar bill every now and again. "Especially when I get a soft one or when it smells. But to be honest, I try not to think about how many germs are on it - that would keep me up all night!"

Show me the money anyway

All this doesn't mean you need to change the way you live or start putting your cash in the wash. Instead, you should keep your immune system safe from viral attacks. Washing your hands frequently is thus very important, especially after handling money and before you eat.

Despite being filthy and arguably disgusting, these bits of paper are still a welcome sight in ang pao every Chinese New Year. And we all love a good crispy note - but have you ever thought about how you would react if you opened your ang pao and found that the giver had popped a damp, crinkled and slightly smelly fifty-dollar bill inside?

"Well, I might think twice about the person who gave it to me," says Deborah Gan, 27, fitness instructor. "But at the end of the day, money's still money and it's the thought behind the ang pao that really counts." After all, they always say that money makes the world go round.

This story was first published in TheLivingRoom.sg in Jan 2008.