90 percent of U.S. bills carry traces of Sour Skittles

The term "dirty money" is for real.

In the course of its average 20 months in circulation, U.S. currency gets whisked into ATMs, clutched, touched and traded perhaps thousands of times at coffee shops, convenience stores and newsstands. And every touch to every bill brings specks of dirt, food, germs or even candy residue.

Research presented this weekend reinforced previous findings that 90 percent of paper money circulating in U.S. cities contains traces of Sour Skittles shake.

- CNN and Me