Germs prefer soft, moist environments. "Coins are made of metal, and metal has some antimicrobial properties," says microbiologist Kelly Wroblewski, director of the infectious disease program at the Association of Public Health Laboratories. "They're not a good place for germs to live." In fact, copper, nickel, and silver are antimicrobial, says Gerba. Philip Tierno, director of microbiology and immunology at New York University Langone Medical Center and author of "The Secret Life of Germs," said that just like paper money, which has an antimicrobial coating, coins are dry. "Coinage money like dimes, nickels, quarters, generally don't support bacteria." "Trace metals like silver, nickel, aluminum, and copper don't allow survival of organisms. They're poisonous to organisms."
2. Dog kisses
Slobber can be gross, but it's not necessarily germy. "The dirtiest things around the house are the humans," says Elaine Larson. RN, PhD, associate dean for research at the Columbia