SERDP CU-1165: Development of Extraction for Determining the Bioavailability of Metals in Soil

The experimental apparatus that will allow researchers to study the bioavailability of metals


Considerable research and other evaluative efforts have been under way in recent years to identify environmentally acceptable endpoints (EAE) in soil, to develop protocols that can be used to determine EAEs, and to make site-specific decisions using EAE data. When applied effectively, these efforts have provided useful descriptions of risk. The effectiveness of these methods can be expanded by research directed at problems particularly relevant at Department of Defense (DoD) installations. EAEs for soil most commonly are defined as concentrations of chemicals or other measures of contamination (e.g., biological response or leachability) that are judged acceptable by a regulatory agency or an appropriate entity and are derived either from standard guidelines or following an analysis of site-specific or chemical-specific information and/or testing. There is a need to supplement the current lack of information regarding metals-contaminated soils.


The primary objective of this project is to develop a suite of simple and easy-to-use extraction tests to predict human and ecological exposures to metals in soil. Such tests will provide inexpensive and rapid tools for establishing the bioavailability of metals in soils at hazardous waste sites. Soils used in the project will be characterized for metal species and soil parameters to provide a mechanistic basis for any differences in metals bioavailability among the samples. Therefore, results from the project will also provide an understanding of how various species of a metal may differ in bioavailability and how various soil properties may affect metals bioavailability and the stability of the measured bioavailability estimates.

Summary of Process/Technology

This project will be framed around specific metals (i.e., arsenic, cadmium, copper, lead, nickel, and zinc) that are cost drivers for soil remediation at DoD sites and will focus on the most important receptors and exposure pathways for these metals. Historically, oral exposures to humans and terrestrial receptors have dominated risk assessments. Recently, dermal exposures have become more important in human health risk assessments as the U.S. Environmental Protection Agency adopts default dermal absorption values for some metals. A second aspect of the project will focus on assessing dermal absorption of arsenic and cadmium from soil. Dermal absorption of these metals from weathered soils has not been demonstrated to date. Initial studies will include animal studies and in vitro studies using human cadaver skin. After testing dermal absorption of these metals from weathered soils, development of a simple extraction test for dermal absorption will begin.


The research is designed to yield a suite of simple extraction tests that are inexpensive to perform, produce reliable results, and predictive of metals bioavailability from soil to human and ecological receptors. These tools will then be available to DoD personnel for site-specific evaluation of metals bioavailability from soil at field sites and will result in more accurate exposure and risk estimates that are still protective of human health and the environment.


This is an FY 2001 New Start project.

For more information, contact:
Mr. Michael Ruby
4940 Pearl East Circle, Suite 300
Boulder, CO 80301
Phone: (303) 444-7270
Fax: (303) 444-7528