Warning: After reading this, you may never want to shake hands again. Following a trip to the toilet, some 95% of people don't wash their hands properly—meaning long enough actually eliminate bacteria, a study finds. Some commit worse hygiene sins: a third don't use soap, and a tenth don't wash their hands at all, LiveScience reports. How did the Michigan State researchers figure this out? By training students to snoop on 3,749 fellow public restroom users.
You should be able to sing "Happy Birthday" twice in the time it takes to wash your hands, according to the CDC—that's 15 to 20 seconds. The average hand-washing time observed, however, was just six seconds. (One interesting finding: If the sink was clean, the time increased.) And, perhaps unsurprisingly, men were less hygienic than women: Just half of guys used soap, while 15% didn't wash their hands. Among women, the stats were 78% and 7%, respectively. Researchers were surprised by the findings: "Past research suggested that proper hand washing is occurring at a much higher rate," said one. (Read more handwashing stories.)