ARCHIVED REPORTS_ROY'S AUTO - HISTORICAL

Home Browse Search

accomplish two objectives: (1) account for the contribution from multiple media to total lead exposure; and, (2) provide a stronger scientific basis for determining a soil lead cleanup level at a specific site. Development of the IEUBK Model for OSWER use. During the 1989-91 time period, use of the EPA IEUBK model was identified as the best available approach for aceomplishing the objectives outlined in the August 1991 guidance. The model integrates exposure from lead in air, water, soil, dust, diet, and paint with pharmacokinetic modeling to predict blood lead levels in children (i.e. , children 6 to 84 months old) , a particularly sensitive population. In the spring of 1991, OSWER organized the Lead Technical Review Workgroup to assist Regional risk assessors and site managers in both using the model and making data collection decisions at CERCLA and RCRA sites. The workgroup was composed of scientists and risk assessors from the Regions and Headquarters, including the office of Research and Development (ORD) , and the Office of Pollution Prevention and Toxic Substances (OPPTS) . In November 1991, the EPA Science Advisory Board (SAB) reviewed the scientific merits of using the IEUBK model for assessing total lead exposure and developing soil lead cleanup levels at CERCLA and RCRA sites. In general, the SAB found the model to be an important advance in assessing potential hea:.'h risks from environmental contaminants. However, the SAB also recommended additional guidance on the proper use of the model. In response to SAB concern over the potential for incorrect use of the model and selection of inappropriate input values both for default and site-specific applications, OSWER developed a comprehensive Guidance Manual for the Integrated Exposure Uptake Biokinetic Model for Lead in Children" (referred to in this interim directive as the "Guidance Manual") . This Guidance Manual assists the user in providing inputs to the model to estimate risks from exposures to lead. It discusses the use of model default values or alternative values, and the application of the model to characterize site risks. Use of the Guidance Manual should facilitate consistent use of the IEUBK model and allow the risk assessor to obtain valid and reliable predictions of lead exposure. The Lead Technical Review Workgroup has been collecting data to further validate the model and to update the Guidance Manual as needed. Relationship to RCRA Corrective Action "Action" Levels. The approach for calculating 'a screening level for lead (including exposure assumptions) , set forth in this Revised Interim Soil Lead Directive, supersedes the guidance provided for calculating -6-