This document is the first volume of the report Lead: Human Exposure and Health Risk Assessments for Selected Areas. This volume describes the quantitative human exposure and health risk assessments conducted to inform the U.S. Environmental Protection Agencys (EPAs) current review of the National Ambient Air Quality Standards (NAAQS) for lead (Pb). As with the last review of the Pb NAAQS, the human exposure and health risk assessments (the risk assessment) for this review reflect multimedia exposure pathways, and their influence on blood Pb levels as an internal index of exposure or dose. The assessment for this review, as with that for the last review, utilizes a case study approach wherein a set of specific locations or case studies associated with policy-relevant Pb exposures are evaluated in detail. The case studies have been selected to provide a perspective on the nature and magnitude of air source Pb exposures and risk in the United States. There are two phases to the risk assessment for the current review: pilot and full-scale. The first phase (the pilot assessment) was presented in the first draft Staff Paper and accompanying technical report (USEPA, 2006a; ICF, 2006), and was the subject of a review by the Clean Air Scientific Advisory Committee (CASAC) on February 6 and 7, 2007 (Henderson, 2007a). The initial full-scale analyses were presented in the July 2007 draft report (USEPA, 2007b) and were the subject of a CASAC review at a public meeting on August 28 and 29, 2007. In response to CASAC recommendations (Henderson, 2007b), additional analyses, using a core modeling approach were conducted to complete the full-scale assessment. All analyses for the full-scale assessment are described in this document, with the initial analyses being the focus in Chapters 3 and 4 and the additional analyses in Chapter 5. Further, given the significant time constraints of this review, risk results are provided in this document without substantial interpretation.
Rather, interpretative discussion of these results is provided in the Staff Paper.