Lead Human Exposure and Health Risk Assessments for Selected ...

1 sources are included in the primary Pb smelter case study, however no such sources are explicitly
2 modeled in the secondary Pb smelter case study.
3 Background information for these case studies is briefly summarized below with regard
4 to: (a) population characteristics, (b) reported emissions, (c) ambient air Pb levels, and (d) the
5 availability of site-specific data characterizing levels of Pb in key media and Pb exposures (e.g.,
6 soil, blood Pb level data).
7 2.2.2.1 Primary Pb Smelter Case Study
8 The primary Pb smelter case study is focused on the currently operating facility in the
9 U.S., which is located in Herculaneum, Missouri. At primary Pb smelters, Pb-bearing ore
10 concentrates are smelted to produce Pb metal. This smelter is one of the largest individual
11 sources of Pb metal in the U.S., has been active for over a century and there exist a large amount
12 of site-specific data in the surrounding area characterizing both media concentrations (soil,
13 indoor dust, outdoor air) and population blood Pb levels (Appendix B, Section B.1).
14 The facility’s century of operation has contributed to Pb contamination of the area
15 surrounding the facility 3 , which has triggered various remediation activities (e.g., removal of Pb­
16 contaminated residential soil) as well as enlargement of the facility property to encompass many
17 of the most heavily impacted private properties. The remediation activity introduces a
18 complication to the risk modeling, especially aspects involving characterization of the
19 relationship of ambient air Pb and residential soil Pb to indoor dust Pb (see Section 3.1.4).
20 Some key aspects of the background information for this case study (Appendix B) are
21 summarized briefly in Table 2-1.
3 Portions of this study area comprise an active Superfund site and are subject to ongoing evaluation under
the Superfund program administered by the Office of Solid Waste and Emergency Response. Methods used in
conducting the human health exposure and risk assessment for the pilot analysis have been selected to address policy
questions relevant to the Pb NAAQS review and consequently may differ from those used by the Superfund
program.
July 2007 2-17 Draft – Do Not Quote or Cite