The U.S. Environmental Protection Agency's (EPA) Integrated Risk Information System (IRIS) Program provides health effects information on chemicals to which the public may be exposed, providing a critical part of the scientific foundation for EPA's decisions to protect public health. EPA has made several changes to this important Program over the past few years, streamlining the assessment development process, improving transparency, and creating efficiencies within the Program. In April 2011, the National Research Council (NRC) made several recommendations to EPA for improving the development of IRIS assessments. The N RC's recommendations were focused on the development of draft assessments, and the NRC was clear that their intent was not to delay assessments. EPA has made progress in implementing these recommendations. Consistent with the advice of the NRC, EPA is implementing these recommendations using a phased approach and is making the most extensive changes to documents that are in the earlier steps of the assessment development process. For assessments that are in the later stages of development, including assessments that have been posted on the IRIS database since the release of the NRC report, EPA is implementing the recommendations as feasible without taking the assessments backwards to earlier steps of the process. Phase 1 of implementing the NRC recommendations has focused on editing and streamlining documents and using more tables, figures, and appendices. EPA is now in Phase 2 of implementing the NRC recommendations and will soon publicly release two draft IRIS assessments that represent a major advancement in implementing the NRC recommendations. EPA is using a new document structure for these draft assessments, including an Executive Summary presenting major conclusions, a Preamble describing methods used to develop the assessment, distinct sections on Hazard Identification and Dose-Response Analysis, and more tables and figures to clearly present data. Additionally as part of Phase 2, EPA is addressing all of the short-term recommendations provided by the NRC. As part of this effort, EPA will make several changes to IRIS assessments. Highlights include: evaluating and describing the strengths and weaknesses of critical studies in a more uniform way; including toxicity values for multiple effects associated with the chemical, if applicable and where the data allow; routinely considering the use of multiple data sets of combined multiple responses in deriving toxicity values, where appropriate; and evaluating existing guidelines to establish clearer criteria for study selection. Phase 3 of implementation will incorporate the longer-term scientific recommendations made by the NRC. The U.S. Congress has directed EPA to issue a progress report to the House and Senate Committees on Appropriations and relevant Congressional authorizing committees to describe EPA's implementation of the NRC recommendations. This report provides Congress, stakeholders, and the public with an update on the IRIS Program and EPA's progress toward implementing the NRC recommendations and improving the Program.
steatosis; mechanism; chlorination; mitochondrial impairment; liver disease;NONALCOHOLIC FATTY LIVER; TUMOR-NECROSIS-FACTOR; TRIGLYCERIDE TRANSFER PROTEIN; ISOLATED RAT HEPATOCYTES; VINYL-CHLORIDE WORKERS; CHRONIC TOXICITY; CARBON-TETRACHLORIDE; HEPATIC STEATOSIS; FACTOR-ALPHA; POLYCHLORINATED-BIPHENYLS