Inhalation Exposure-Response Assessments for Five Chemicals
Inhalation exposure-response assessments for five chemicals (acrolein, ethylene oxide, hexachlorocyclopentadiene, hydrogen sulfide, and phosgene) for less-than-lifetime durations are being developed to inform the development of the Inhalation Exposure-Response Analysis Methodology Document. These assessments are being developed based on the comments from the Science Advisory Board and the Risk Assessment Forum (RAF) on the draft Acute Reference Exposure (ARE) methodology, and from comments on the RfD/RfC Improvement Pilot Project developed under the IRIS Program. In these assessments, the decision on the critical endpoint is determined through the use of an exposure-response array of all available acute inhalation data, wherein the key studies are also identified. Based on the availability of highly detailed data from all of the identified key studies, an appropriate analytical approach is determined. Additionally, this analytical approach provides the basis for duration extrapolations to estimate the appropriate durations of exposure. These example assessments will help to support the development of an inhalation exposure-response analysis methodology as well as develop the basis for deriving human health effect reference values that will be useful to the EPA Program Offices (e.g., Office of Air and Radiation; National Homeland Security Research Center).