Abstract
Recently the Centers for Disease Control and Prevention lowered the blood Pb reference value to
5 μg/dL. The lower reference value combined with increased re-purposing of post-industrial
lands are heightening concerns and driving interest in reducing soil Pb exposures. As a result,
regulatory decision makers may lower residential soil screening levels (SSLs), used in setting Pb
cleanup levels, to levels that may be difficult to achieve, especially in urban areas. This paper
discusses challenges in remediation and bioavailability assessments of Pb in urban soils in the
context of lower SSLs, and identifies research needs to better address those challenges. Although
in situ remediation with phosphate amendments is a viable option, the scope of the problem and
conditions in urban settings may necessitate that SSLs be based on bioavailable rather than total
Pb concentrations. However, variability in soil composition can influence bioavailability testing
and soil amendment effectiveness. More data are urgently needed to better understand this
variability and increase confidence in using these approaches in risk-based decision making,
particularly in urban areas.
