Be careful whose hand you shake: One out of three men still don't wash their hands after they go to the bathroom. In the past two years, health authorities have conducted a number of campaigns hoping to urge people to wash their hands more often, especially after using restrooms. Hands are a primary means for spreading germs that cause colds, the flu, and food poisening. But when researchers for the American Society for Microbiology spied on 6,000 people in public bathrooms, they found that nearly a third walked right past the sink on their way to the exit. A similar study two years ago found that only 25 percent failed to wash their hands, so the message clearly isn't getting through. "Guys need to step up to the sink," soap spokesman Brian Sansoni tells the Associated Press. The study also found that 12 percent of women failed to wash their hands. The study discovered strong regional differences in hand-washing habits: 79 percent of male New Yorkers washed up, as did 81 percent of Chicagoans. But at Atlanta's Turner Field, just 57 percent of guys stopped at the sink.