When I was a child, my mother would tell me to wash my hands after handling money. Since we predominately use credit and debit cards we don’t hear that as often today. But the warning remains important to heed, because cash comes with a little extra.

Researchers at New York University’s Dirty Money Project conducted the first comprehensive study of DNA on dollar bills and found that currency is an exchange for hundreds of different kinds of bacteria. They identified more than 3,000 types of bacteria in addition to viruses, fungi, plant pathogens, and small amounts of anthrax and diphtheria. Only about 20% of the non-human DNA could be identified because the majority have yet to be cataloged in genetic data banks.

The most abundant species on the bills are known to cause acne. Others are linked to gastric ulcers, pneumonia, food poisoning, and staph infections. And to the researchers’ surprise, bacteria can continue to grow on the bills, especially when contained in a wallet on our warm bodies.

The U.S. dollar bill is printed on a cotton-linen blend. The good news is that the bills typically last less than two years. The bad news is that it is a medium conducive to the living bacteria.

Canadian money is printed on sheets of flexible plastic polymer film, which long outlast the cotton-based bills. Although, some bacteria does live longer, significantly fewer bacteria are found on them.

Whether handling money or not, washing or sanitizing hands often, and keeping our hands away from our faces, is our best defense against picking up unwanted organisms.

©2014, Mary K. Doyle

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