Tony Soprano and his cronies aren't the only ones with dirty money. A new study presented today at the General Meeting of the American Society for Microbiology reveals that many one-dollar bills are filthy, bacterially speaking at least. "One-dollar bills are widely used, and each is exchanged many times," says researcher Peter Ender of Wright-Patterson Air Force Base. "If some are contaminated with bacteria, there is potential to spread these organisms from person to person."

Although Ender and his colleagues did not actually demonstrate that paper currency can pass bacteria among the population, they did show that it is highly contaminated. The group analyzed 68 singles collected from a food concession stand at a high school sporting event and from a grocery store near Dayton, Ohio. At both locations, people were asked to exchange an old bill for a new one. The researchers discovered that 59 of the bills carried Staphylococcus, Streptococcus, Enterobacter, Pseudomonas and other pathogens that pose a risk to hospitalized or immune-compromised individuals. Another five bills bore Staphylococcus aureus and Klebsiella pneumoniae, bacteria that readily infect healthy people. And only four bills were cleanbringing new meaning to the old expression, buyer beware.