On Saturday, Nov. 15, a toxic chemical leak at a DuPont manufacturing plant outside of Houston killed four workers and hospitalized another, serving as another troubling example of the need for stronger chemical safety standards. The chemical involved in the leak, methyl mercaptan, can cause eye and lung irritation and can be fatal at high levels. Numerous other U.S. facilities use and store this chemical, including those featured in a new interactive map by the Center for Effective Government.