(NaturalNews) An analysis by New York University found 3,000 separate species of bacteria living on U.S. one-dollar bills, far more than had ever been detected in prior studies. Many of the species found are able to cause disease in humans, and many exhibited antibiotic resistance.
"It was quite amazing to us," researcher Jane Carlton said. "We actually found that microbes grow on money."
The unpublished study from New York University's Dirty Money Project is the first ever comprehensive analysis of DNA collected from dollar bills. By analyzing DNA, the researchers were able to identify many more species than prior studies, which relied upon culturing live bacteria and then identifying them visually using microscopes.
The study may have significant public health implications, as experts grow increasingly concerned about disease transmission in a globalized world. Paper money is one of the most commonly transmitted items worldwide, making it a major potential disease vector.
"A body-temperature wallet is a petri dish," said Philippe Etienne, managing director of Innovia Security Pty Ltd., which makes the paper used for currency in 23 separate countries.
"Spectrum of life"
Researchers collected DNA samples from 80 one-dollar bills acquired from a Manhattan bank. In total, they collected 1.2 billion DNA segments, which they sequenced and uploaded into a computerized database. The data took up 320 gigabytes of space, roughly equivalent to an entire library of medical texts.
"We were casting the broadest possible net," researcher Steven Sullivan said.
About half the DNA collected came, unsurprisingly, from human beings. Other life forms represented included bacteria, viruses, fungi, plant pathogens, horses, dogs and even white rhino.
Only about 20 percent of the nonhuman DNA samples could be identified, because many microorganisms have not yet had their genomes catalogued. Among those identified, the most common bacterial species was one responsible for acne. Other species identified included Bacillus cereus (which causes food-borne illness), Corynebacterium diphtheria (diphtheria), Escherichia coli (food poisoning), Helicobacter pylori (gastric ulcers), Staphylococcus aureus (skin infections), and even Bacillus anthracis (anthrax). Many of the species identified carried antibiotic-resistant genes.
"We had a lot of the spectrum of life represented on money," researcher Julia Maritz said.
Although broader in scope, the new study is not the first to look at money as a route for bacterial transmission. Much recent research has focused on whether traditional cotton-linen blends such as those used for U.S. currency are more or less hospitable to bacteria than the newer polymer films that many countries are adopting in order to extend currency life.
Worldwide, governments spend about $10 billion per year printing currency, much of it designed simply to replace older, worn-out bills.
In a study published in the journal Foodborne Pathogens and Disease in 2010, researchers from the University of Ballarat, Australia tested bills collected at cafeterias, coffee shops and supermarkets in 10 different countries. They found that while bacterial levels varied widely by location, in general less bacteria were found on polymer than on cotton-based currencies.
"The thing about a polymer note is that it is not absorbent," Etienne said. "There is a cleanliness benefit, which is a health issue."
On the other hand, a study published in Antimicrobial Resistance and Infection Control in 2013 found that when bacteria were deliberately grown on currency from seven different countries, the bacteria on polymer currencies survived longer.
The more we handle currency, the longer the bacteria are likely to live, as they feed of the oils from our hands.
"We provide the nutrients when we handle the bank notes," said Nabil Lawandy of Spectra Systems Corp., which designs anti-counterfeit measures for 19 different central banks.