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NEW YORK — When you think about it, you can imagine the germs we pass along to each other on our dollar bills. But new research sheds information about that very thing that might gross you out.

In the first comprehensive study of the DNA found on a set of dollar bills collected in New York, researchers at New York University’s Dirty Money Project discovered that currency is a medium of exchange for thousands of different bacteria as cash passes from person to person. That’s according to a report in the Wall Street Journal.

3,000 bacteria on $1 bills

By analyzing genetic material on $1 bills, the NYU researchers identified 3,000 types of bacteria in all—many times more than in previous studies that examined samples under a microscope.

However, they could identify only about 20 percent of the non-human DNA they found because so many microorganisms haven’t yet been cataloged in genetic data banks.

Easily the most abundant species they found is one that causes acne. Others were linked to gastric ulcers, pneumonia, food poisoning and staph infections, the researchers reported.

Some carried genes responsible for antibiotic resistance.

“It was quite amazing to us,” said Jane Carlton, director of genome sequencing at NYU’s Center for Genomics and Systems Biology where the science took place. “We actually found that microbes grow on money.”

Their unpublished research offers a glimpse into the international problem of dirty money. From rupees to euros, paper money is one of the most frequently passed items in the world. Hygienists have long worried that it could become a source of contagion.

“A body-temperature wallet is a petri dish,” said Philippe Etienne, managing director of Innovia Security Pty Ltd., which makes special bank-note paper for 23 countries.

Read more about this story in the Wall Street Journal

Facts about the dollar bill

  • It’s made of 25 percent linen and 75 percent cotton
  • It remains in circulation 18-21 months before it wears out
  • Almost half, 48 percent, of all notes printed by Bureau of Engraving and Printing are $1 bills