EPA’s mission is to protect human health and the environment. EPA’s IRIS Program supports this mission by identifying and characterizing the health hazards of chemicals found in the environment. Each IRIS assessment can cover a chemical, a group of related chemicals, or a complex mixture. IRIS assessments: Are the preferred source of toxicity information used by EPA Are an important source of toxicity information used by state and local health agencies, other federal agencies, and international health organizations The IRIS Program is located within EPA’s National Center for Environmental Assessment (NCEA) in the Office of Research and Development (ORD). The placement of the IRIS Program in ORD is intentional. It ensures that IRIS can develop impartial toxicity information independent of its use by EPA’s program and regional offices to set national standards and clean up hazardous sites.