Ten years ago, the Environmental Protection Agency only knew whether a small fraction of the 80,000 chemicals in use were hazardous to people or the environment. That changed in 2005 after Robert Kavlock, deputy assistant administrator for science in the EPA's Office of Research and Development, established the ToxCast Lab. It can quickly screen large numbers of chemicals for health effects. For that, he was named one of the 33 finalists for this year's Service to America Medals. He joined Tom Temin on the Federal Drive to further discuss his work, and the problems it solved. View a gallery of Sammies finalists.