Impact/Purpose:

The objective of this task is to develop state-of-the-science methods for evaluating toxic elements. These methods will include measuring bioavailable concentrations of toxic elements as well as enhanced traditional methods. Once established, the performance of these methods will be demonstrated on a small set of samples. Procedures will be documented such that they are readily transferable to EPA and non-EPA researchers.

Specific objectives of this task include:

1) Development of more sensitive and rapid quantitative procedures for evaluating exposure to toxic elements.

2) Assessment of the bioavailability of toxic elements in environmental media using bioavailability tools.

3) Application of this data to improve the scientific basis of site and source specific risk assessments.

4) Application of these methods to fill critical data gaps identified in the aggregate/cumulative exposure and risk research area of the Human Health Risk Assessment research plan.

Description:

Metals exist in a variety of chemical and physical forms in the environment. As indicated in EPA's "Draft Action Plan for the Development of a Framework for Metals Assessment and Guidance for Characterizing and Ranking Metals" (available on the EPA web), each environmental form of the metal has its unique fate/transport, bioavailability, bioaccumulation, and toxicity characteristics. Therefore, when assessing hazards and risks that metals and metal compounds pose, such properties such as speciation, bioavailability, bioaccumulation, persistence, and toxicity need to be considered.

This task focuses on the development/improvement of traditional methods for measuring toxic elements as well as incorporating bioavailability approaches to better characterize human and ecological exposure from various sources and pathways. Once these methods have been developed and applied appropriately, these methods can provide reliable data needed to evaluate exposure to toxic elements. Research is needed to produce data under varying environmental conditions to help establish relationships between total concentrations and bioavailable concentrations to yield a better understanding of the absorbed dose of toxic elements.

This task supports the Agency's effort to improve the scientific basis of risk assessments. These risk assessments include site and source specific assessments.

Record Details:

Record Type:PROJECT

Start Date:10/01/2003

Projected Completion Date:09/01/2007

Record ID: 83563

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Project Information:

Progress :The researchers have conducted a customer value analysis to assess the uses and needs of the clients. The researchers have met with the Human Exposure Program Science Lead, the Associate Laboratory Director for research areas related to human exposure and air research, and the clients. A formal presentation on MDAB/HEASD Metals Bioavailability Research was given in Cincinnati, OH to NRMRL scientists and the NRMRL ALD Greg Sayles and NERL ALD Ross Highsmith.

The researchers have established a collaboration with NRMRL-RTP on the project "Evaluation of the Effectiveness of Coatings in Reducing Dislodgeable Arsenic, Chromium, and Copper from CCA Treated Wood." Standard Operating Procedures (SOP) US EPA, NERL, QATS, SOP MDAB-006 and MDAB-007 have been approved as well as "QAPP for the CCA Bioavailability Sub-Project." Two sets of soil samples have been collected.

The bioavailability laboratory has been equipped. SOPs US EPA, NERL, QATS, SOP MDAB-008.0 and MDAB-017.0 have been approved and other SOPs are being developed. "QAPP for the Toxic Element Bioavailability Laboratory" has been approved. The Health and Safety Research Protocol # 452 "Bioavailability of Environmental Contaminants" has been approved.

Literature databases for bioavailability techniques for arsenic, copper and chromium have been developed.

The researchers have actively supported HUD's "American Healthy Homes Survey" (see American Healthy Homes Study task) with document reviews and developed soil collection SOP US EPA, NERL, QATS, SOP MDAB-24.0.

The researchers continue to review bioavailability documents for the Human Health Bioavailability Workgroup in relation to guidance on this research area.

The following presentations have been given: "Bioavailability of Metals in Contaminated Soil and Dust, Karen D. Bradham" presented at th 19th Annual Regional Risk Assessors Meeting, Boston, MA May 5, 2004; "Bioavailability and Toxicity of Metals in Soils," Karen D. Bradham, presented at Fall 2003 Environmental Information Seminar Series, North Carolina Central University, Durham, NC, September 22, 2003; "Effect of Soil Properties on the Toxicity and Bioavailability of Metals," Karen D. Bradham, presented at 7th International Biogeochemistry of Trace Elements, Uppsala, Sweden, June 15-19, 2003; "Bioavailability of Metals in Environmental Media," Karen D. Bradham, presented at Science Forum 2003, Washington, DC, May 5-7, 2003; "Effect of Soil Properties on the Bioavailability and Toxicity of Metals to Earthworms," Karen D. Bradham, presented at Society of Environmental Toxicology and Chemistry 23rd Annual Conference, Salt Lake City, UT November, 2002.

An abstract has been submitted to the 8th International Conference on the Biogeochemistry of Trace Elements, Adelaide, Australia, April 3-7, 2005 for an invited presentation entitled "Methods to Evaluate Risk from CCA-Treated Wood Products."

Relevance :The data obtained by applying the methods developed will provide a better understanding of exposure concentrations of toxic elements within and between environmental compartments as well as total and bioavailable concentrations. The development of bioavailability techniques will provide useful screening tools for hazard assessment and risk management. For example, the methods developed in this task will be applied to the house dust and soil samples collected in the American Healthy Homes Study (AHHS) being conducted in conjunction with HUD (see American Healthy Homes Study task). The AHHS will provide the first national estimates of the levels of exposures in residential settings to environmental contaminates such as arsenic. In addition, soils collected from beneath coated chromated copper arsenate (CCA)-treated wood decks at the NRMRL-RTP field test site will be evaluated for the bioavailabiity of As and Cr. This data will be provided to NRMRL-RTP and will complement the dermal transfer data to be provided to OPP for guidance on management of the As risk from CCA-treated wood. Research findings will be disseminated to clients and scientific community through presentations, SOPs, EPA reports, and/or journal articles.

Clients : NRMRL-Cin (Kirk Scheckel), NRMRL-RTP (Mark Mason), OSP (Randy Wentsel), Human Health Bioavailability Workgroup, HUD (Warren Friedman)

Project IDs:

ID Code :19580

Project type :OMIS