You probably already know that letting your baby play with your smartphone will not make him smart - but there’s a risk you may not have considered yet: Your smartphone carries germs. Even if you wash your hands frequently, you still transfer bacteria and dirt to your phone when you use it, hand it to a friend, set it down on the counter at Starbucks, drop it in your diaper bag… In one British study, researchers found bacteria on 92 percent of mobile phones they tested. Worse yet, one in six phones were contaminated with E. coli bacteria (in other words, fecal matter), which can cause serious stomach issues (potentially life threatening for babies). Viruses, like the flu, can live on some surfaces for a day or more. And since babies explore with their mouths, why take the risk?