It's long been known that money is one of the dirtiest things on the planet, given the number of human hands coins and dollar bills touch from their mint date. A new project seeks to that knowledge a step further and studies the exact microbes living on our nation's paper currency, NPR reported.

Led by biologist Jane Carlton of New York University, the project's intention is to better understand the microscopic organisms on money and determine which, if any, lead to the spread of disease. She and her colleagues haven't published their full research yet, but they've already identified a wide variety of harmless and harmful bacteria.

"We're not trying to be fear mongers, or suggest that everyone goes out and microwave their money," Carlton told Shots. "But I must admit that some of the $1 bills in New York City are really nasty."

By a wide margin, the most common bacteria found on dollar bills is the type that causes acne, suggesting that maybe teenagers should own debit cards as early as possible. The second most common bacteria type wasn't harmful at all, but one that lives on human skin without any negative side-effects, according to NPR.

Mouth microbes and vagina microbes were also found in Carlton et al's search, representing the many people who lick their hands when counting money (whom I thought were a dying breed) and don't wash their hands after going to the bathroom (never a dying breed).

Carlton's research confirmed past findings of anthrax on paper money. But the traces in money weren't even enough to cause a reaction. Only when the substance is "weaponized" is it dangerous, according to Carlton.

"Anthrax is a very common bacteria in soil," Carlton said. "People who work with soil, like farmers, are often exposed to it. It's only when anthrax is weaponized and sent through the mail that it causes those issues."

Though the project increases our knowledge of the ecosystems present on money, it doesn't -- at least not in its current form -- gauge the scale of paper currency's role in the spread of diseases, or, as Carlton says, "antibiotic-resistant genes." Rather, it establishes that microbes are being moved and identifies which ones.

"Now we know that viable bacteria are on money and could serve as a mode of transmission for antibiotic-resistant genes," Carlton says. "Money is a frequent route of contact between people in New York City."