The document is the second in a series of volumes developed for the U.S. Environmental Protection Agency, Office of Toxic Substances to assist in the assessment of exposure to chemical substances. This report presents methods that can be used to estimate exposure to chemical substances in the ambient environment and includes many tools, data sources, and models that are useful in the exposure estimation procedures. The volume is organized to reflect the flow of information in an ambient exposure assessment. Sections 2 and 3 provide information on the preliminary data required, i.e., production volume, physicochemical properties, and uses of the chemical substance. Section 4 contains a description of the availability and use of monitoring data bases and how monitoring data are integrated in the overall methods. Section 5 indicates how the population methods (Volume 4) fit into the overall process. Section 6 is the core of this volume; it addresses the analytical framework for calculating exposure and discusses how to access appropriate data for each of the analytical elements. To supplement the text, an Information Resource Matrix which indexes data bases and other resources is included as Appendix A; a list of chemicals studied and regulated by federal agencies as of 1984 is provided as Appendix B; and examples of pertinent data base outputs are given in Appendix C.

Project Officer: Michael A. Callahan. Vesar, Inc. "July 1985." "EPA 560/5-85-002." "Exposure Evaluation Division, Office of Toxic Substances, Washington, D.C. 20460." Includes bibliographical references.