It's easy to get carried away when you start talking about graphene. Its properties hold the promise of outright technological revolution in so many fields that it has been called a wonder material. Two recent studies, however, give us a less than rosy angle. In the first, a team of biologists, engineers and material scientists at Brown University examined graphene's potential toxicity in human cells. Another study by a team from University of California, Riverside's Bourns College of Engineering examined how graphene oxide nanoparticles might interact with the environment if they found their way into surface or ground water sources.