US EPA

This status report provides a review of advances in the state-of-the-science for interspecies inhalation gas dosimetry related to the lower respiratory tract and the body.

The RfC Methods document (Methods for Derivation of Inhalation Reference Concentrations and Application of Inhalation Dosimetry; EPA/600/8-90/066F, October 1994) provides the basis for EPA extrapolation of data from animal toxicology studies to estimate delivered dose in humans as part of the development of inhalation reference values (i.e., RfC values). This report reviews advances in the state of the science for inhalation gas dosimetry used for the tracheobronchial (TB) and pulmonary (PU) regions of the respiratory tract and the procedure used for the systemic or extrarespiratory (ER) region that have occurred since the publication of the RfC Methods. In addition, this report presents reviews and discusses information and data on inhalation dosimetry in children pertaining to the derivation of an RfC.  The 2009 Status Report (Advances in Inhalation Dosimetry of Gases and Vapors with Portal of Entry Effects in the Upper Respiratory Tract; EPA/600/R-09/072, September 2009) reviewed advances in the state of the science for inhalation gas dosimetry related to the URT or nasal tract region. The primary results from these reviews include empirical information related to the assumptions underlying the current methodology used by EPA, as well as how the state of the science and advanced dosimetry modeling techniques inform these assumptions. The primary intent of these reports is to serve as source documents for potential revisions to the dosimetric application of the Agency’s RfC Methods.

This report reviews advances in the state of the science for inhalation gas dosimetry used for the tracheobronchial (TB) and pulmonary (PU) regions of the respiratory tract and the procedure used for the systemic or extrarespiratory (ER) region that have occurred since the publication of the RfC Methods.

U.S. EPA. 2011 Status Report: Advances In Inhalation Dosimetry For Gases With Lower Respiratory Tract and Systemic Effects. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-11/067, 2011.