Ingestion of Pb in soil and surface dust is a major exposure pathway in children and contributes to elevated blood Pb levels in children.  Recent CDC (2012) recommendations to lower the definition of elevated blood lead in children from 10 �g/dL to 5 �g/dL, thus implicating soils with moderate Pb contamination (e.g., 150 � 400 ppm).  This presents a challenge, as moderate Pb contamination is widespread, particularly in urban soils.  Excavating and replacing soil to achieve soil Pb levels of 150 ppm or less in highly urban communities would be cost prohibitive, technically difficult, highly disruptive, and possibly ineffective in cases where background Pb levels are higher.  Amending agents and other in situ remedies offer potential for a more cost effective, technically feasible and publically acceptable means towards achieving CDC recommendations.  Agents used to amend or immobilize Pb in soil can be divided into two general categories:  organic (bark saw dust; xylogen; bagasse; poultry manure; compost; and sewage sludge) and inorganic compounds (lime; bentonite; fly ash; and  various phosphorous containing compounds) (EPA, 2007).  Of the aforementioned agents, phosphate agents have been studied most extensively for their effects on oral bioavailability of Pb. However, the extent and duration of the stabilizing effect needs to be better characterized along with a better understanding of the factors that control these processes before phosphate amendments can be routinely utilized. Of additional interest is the potential mobilizing effect that phosphates may have on soil-borne arsenic.  This session will explore the state of the science of amending agents under investigation for the stabilization of Pb.  This talk will overview the state of the science of amending agents under investigation for the stabilization of Pb and will serve as an introduction to a mini-session devoted to the stabilization of lead in soils.

State of the science: New recommendations on elevated Pb blood level and implications to lead soil remediation

246th National Meeting (2013)

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