Exposure Summaries for IRIS Chemicals.

Abstract

The Integrated Risk Information System (IRIS), prepared and maintained by the National Center for Environmental Assessment (NCEA) of the U.S. Environmental Protection Agency (U.S. EPA), is an electronic database containing information on human health effects that may result from exposure to various chemicals in the environment. IRIS was initially developed for EPA staff in response to a growing demand for consistent information on chemical substances for use in risk assessments, decision-making and regulatory activities. The information in IRIS is intended for those without extensive training in toxicology, but with some knowledge of health sciences. The heart of the IRIS system is its collection of computer files covering individual chemicals. These chemical files contain descriptive and quantitative information in the following categories: Oral reference doses and inhalation reference concentrations (RfDs and RfCs, respectively) for chronic noncarcinogenic health effects. Hazard identification, oral slope factors, and oral and inhalation unit risks for carcinogenic effects. To aid the IRIS staff in developing an individual chemical file, NCEA’s Exposure Assessment and Risk Characterization Group (EARCG) provides supplementary information regarding human exposure. Although not a part of the IRIS file itself, the exposure summary is useful in providing the scientists and risk managers involved with a broader understanding of relevant exposure pathways, levels of exposure, and exposed populations for specific IRIS chemicals.