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suggested that proposed different threshold levels (primary and <br /> secondary) for screening decisions, action decisions and land use <br /> patterns. <br /> Findings from the three cities (Baltimore, <br /> Boston and <br /> Cincinnati) of the Urban Soil Lead Abatement Demonstration <br /> Project (peer review scheduled for completion in late 1994) <br /> indicate that dust and paint are major contributors to elevated <br /> blood lead levels in children.— Furthermore, preliminary findings <br /> suggest that any strategy to reduce overall lead risk at a site <br /> needs to consider not only soil, but these other sources and <br /> their potential exposure pathways. (For further information on <br /> this demonstration project, contact Dr. Rob Elias, USEPA/ORD, <br /> Environmental Criteria and Assessment Office (ECAO) , RTP, (919) <br /> 541-4167 . ) <br /> Finally, in its efforts to develop this interim dir=ctive, <br /> the OSWER Soil Lead Workgroup has met with other EPA workgroups <br /> including the TSCA Section 403, Large Area Lead Sites, and Urban <br /> Lead workgroups, as well as other Federal agencies including the <br /> Agency for Toxic Substances and Disease Registry, the Centers for <br /> Disease Control, and the Department of Housing and Urban <br /> Development. <br /> Derivation of Lead Screening Levels. Development of the <br /> residential screening level in this interim directive required <br /> two important OSWER decisions. 1) OSWER determined that it would <br /> seek to achieve a specific level of protectiveness in site <br /> cleanups; generally, OSWER will attempt to limit exposure to <br /> soil lead levels such that a typical (or hypothetical) child or <br /> group of similarly exposed children would have an estimated risk <br /> of no more than 5% of exceeding the a 10 µg lead/dl blood lead <br /> level. This 10 pg/dl blood lead level is based upon analyses <br /> conducted by the Centers for Disease Control and EPA that <br /> associate blood lead levels of 10 µg/dl and higher with health <br /> effects in children; however, this blood lead level is below a <br /> level that would trigger medical intervention. 2) In developing <br /> the residential screening level, OSWER has decided to apply the <br /> EPA's IEUBK model on a site-specific basis. This model has been <br /> designed specifically to evaluate exposures for children in a <br /> residential setting. Current research indicates that young <br /> children are particularly sensitive to the effects of lead and <br /> require specific attention in the development of a soil screening <br /> level for lead. A screening level that is protective for young <br /> children is expected to be protective for older population <br /> subgroups. <br /> . In general, the model generates a probability distribution <br /> of blood lead levels for a typical child, or group of children, <br /> exposed to a particular soil lead concentration and concurrent <br /> lead exposures from other sources. The spread of the <br /> distribution reflects the observed variability of blood lead <br /> -8- <br />