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Drugs & Health Blog

Dirty Money: How Cocaine and Germs Contaminate Our Cash

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The NIDA Blog Team

Q: What do cocaine and bacteria have in common?

A: They both contaminate our cash.

While most of the dollar bills you come into contact with would test positive for cocaine, that doesn’t mean that they were used to snort cocaine. In fact, less than 1 percent of people age 12 or older even use the drug.  

It happens because cocaine is a very fine powder that easily transfers from bill to bill. One bill with cocaine on it can contaminate an entire cash drawer or ATM. It’s a little like someone with a cold—if he or she sneezes on you, the chances are good that you’ll catch what the individual has.

Graphic of text saying, "Q: What do cocaine and bacteria have in common? A: They both contaminate our cash.”  Below that, text says, “Nearly 9 out of 10 dollar bills in the United States test positive for cocaine residue. The amount of cocaine found on money is usually minuscule—a nanogram to a milligram.” Beside the text is a graphic of 10, one-dollar bills with 9 of them containing red marks. Below that, text says, “Yet, less than 1% of people age 12 and older are using cocaine.” Beside the text is a graphic of 100 people and only 1 is colored red. Below that is a graphic of a person at an ATM with text beside it that says, “Cocaine is a very fine powder that easily transfers from one bill to another. It only takes one dollar that has any trace of cocaine to contaminate an entire ATM.” Below that, text says, “Researchers have identified more than 3,000 different types of bacteria on dollar bills.” Beside the text is a graphic of a one-dollar bill with a close-up of bacteria. Below that, text says, “Just another good reason to wash your hands!” Beside the text is a graphic of hands washing and a red check-mark.

But don’t worry. Your stash of cash has only a tiny amount of cocaine on it—not enough to get you high or cause you to fail a drug test.

And What About Bacteria?

Well, germaphobes beware—researchers from New York University found hundreds of different bacteria on dollar bills. In all, they identified over 3,000 different types of bacteria that caused pneumonia, food poisoning, and staph infections. 

Want To Know What’s in Your Pocket?

Where’s George? allows users to enter and track dollar bills. It shows how far money can travel while it is in circulation. 

So, the bottom line here is that money is dirty. And while cocaine is not likely to get on your skin from handling money, germs will. So, we suggest washing your hands frequently.







Sources for Infographic:

Biello, D. (2009 Aug 16). Cocaine contaminates majority of U.S. currency. Scientific American. Retrieved November 3, 2014, from

Carlton, J. (2014).  The Dirty Money Project.  Mapping NYC’s MetaGenome: A Research Project at New York University.

Oyler, J., Darwin, W.D., & Cone, E.J. (1996 Jul/Aug). Cocaine contamination of United States paper currency. Journal of Analytical Toxicology, 20(4):213–216. Retrieved November 3, 2014, from

Substance Abuse and Mental Health Services Administration. (2014 Sept). Results From the 2013 National Survey on Drug Use and Health: Summary of National Findings, NSDUH Series H-48, HHS Publication No. (SMA) 14-4863: Rockville, MD: SAMHSA. Retrieved November 3, 2014, from

Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.


That's a me-stake
What both cocaine and bacteria have in common is that they are both dangerous and harmful to the human body. It surprises me that less than 1% of people 12 and older have never used cocaine in their lives and still yet today according to this article we just about every dollar bill would test positive for cocaine. That must be a pretty big sign that cocaine is snorted a lot in this world way to much.
Can cocaine get in my body by touch

It’s unlikely that cocaine could get into your body by touch. For more information, please visit our Cocaine Drug Facts Page:

How likely is it to get sick from bills? Also, is there a way to clean the money?

Great questions! The U.S. Department of the Treasury may be able to better answer your questions. You can find contact information here: And be sure to check out the article we linked to in the “Dirty Money” blog post for more details about contaminated bills.