Think about it — that dollar bill in your wallet may have been in the sweaty hands of a 10-year-old waiting to buy cotton candy at the state fair last summer, or worse — in the hands of someone who didn’t wash their hands after using the bathroom. And yeah — both of those people could have had colds when they handled that dollar bill. And they didn’t use a tissue to wipe their nose. They used their hands. Gross!

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A study published in the Southern Medical Journal in 2002 analyzed 68 dollar bills collected from people in Ohio. Of those 68 dollar bills, 94 percent of them harbored bacteria, and although much of it was benign, a small percentage carried bacteria that could cause infections like pneumonia.

Of the 68 bills tested, 59 of them harbored bacteria that would be harmless to healthy people, but could cause serious infections in people with already compromised immune systems.   But you should also know that the chances of getting sick from one of these bacteria-laced dollar bills is slim, and that’s because your skin is a pretty good protector against germs. As long as you don’t stick the dollar bill in your mouth and chew it up, you should be OK. But if you’re touching particularly dirty dollar bills, it might be a good idea to wash your hands with soap and water afterward.

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Interestingly, a study at the University of Michigan in 2009 found that some bills actually carry traces of cocaine. And it’s not just a few. 90 percent of the bills tested in the study were positive for cocaine. So yes, there’s a very good chance that you’re carrying around drug money in your wallet. Not to worry, though. A 1997 Argonne National Laboratories study found that the cocaine is so deeply imbedded in the fibers of our paper money that it is impossible for it to rub off on your hands. Phew! For a moment there, I thought my son could get high off his lunch money.   What about coins? Are they as germy as bills? Turns out that coins don’t harbor the same bacteria because metal does not hold germs like paper does.

I’ve read about an ATM that used to be in Japan that would “clean” your money for you. You would simply insert your yen, and the money would be instantly heated to a high enough temperature that all germs would be killed. Out it would come — clean and crisp as the day it was printed. I’m not sure if they still use them, but I do know that we Americans wouldn’t know what to do with them. To us, an ATM that cleans money would just be a vending machine that doesn’t work.

So what’s the bottom line? Dollars bills can harbor germs, but so can thousands of other surfaces we come into contact with daily. Be smart, wash your hands often, and don’t stick your fingers in your mouth (or pick your nose) if you can help it when you’re at places like the supermarket or a public restroom.

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