What is IRIS?
EPA's Integrated Risk Information System (IRIS) is a human health assessment program that evaluates information on health effects that may result from exposure to environmental contaminants. Through the IRIS Program, EPA provides the highest quality science-based human health assessments to support the Agency’s regulatory activities. The IRIS database contains information on more than 550 chemical substances containing information on human health effects that may result from exposure to various substances in the environment. The IRIS database is prepared and maintained by the EPA’s National Center for Environmental Assessment (NCEA) within the Office of Research and Development (ORD).
The heart of the IRIS database is its collection of searchable documents that describe the health effects of individual substances and that contain descriptive and quantitative information in the following categories:
- Noncancer effects: Oral reference doses and inhalation reference concentrations (RfDs and RfCs, respectively) for effects known or assumed to be produced through a nonlinear (possibly threshold) mode of action. In most instances, RfDs and RfCs are developed for the noncarcinogenic effects of substances.
- Cancer effects: Descriptors that characterize the weight of evidence for human carcinogenicity, oral slope factors, and oral and inhalation unit risks for carcinogenic effects. Where a nonlinear mode of action is established, RfD and RfC values may be used.
Evolution of IRIS
1985: The Integrated Risk Information System (IRIS) was created by EPA to develop consensus opinions about the health effects that may result from chronic exposure to various substances in the environment, and to provide these opinions in a database accessible across the Agency. By providing a common source of health effects information, the intent was to help EPA programs reduce inconsistency in toxicity assessments.
1985 to 1995: IRIS consensus opinions on the health effects of substances were developed by the RfD/RfC Work Group and the Carcinogen Risk Assessment Verification Endeavor Work Group, or CRAVE. The consensus opinions were documented in IRIS Summaries. During this period, the importance of IRIS grew as regulatory programs in EPA and states came to rely on IRIS information in decision making.
1995-1997: EPA conducted an IRIS pilot program to incorporate new operational procedures, the development of a Toxicological Review support document, the introduction of a process for incorporating peer review into the IRIS review process, and a revised consensus review process consisting of a standing group of senior health scientists representing the Program Offices and Regions in the review of all health assessments.
1997- Present: The IRIS database was uploaded to the Internet. Outreach to IRIS users was improved through an updated IRIS Hotline service. Opportunities for public involvement were provided through annual solicitation (via Federal Register notice) for submission of scientific information relevant to new chemical assessments, and through posting external review drafts of IRIS assessments on EPA’s web site and consideration of public comments.
For other questions about IRIS, review our list of frequent questions.