161319 Geochemical controls on uranium mobility to inform human health exposure assessment in the Church Rock Mining District: Navajo Nation, NM

Wednesday, November 7, 2007: 12:45 PM

Jamie L. deLemos, MS , Department of Civil and Environmental Engineering, Tufts University, Medford, MA
Margaret Menache, PhD , Community Environmental Health Program, University of New Mexico, Albuquerque, NM
Doug Brugge, PhD, MS , Department of Family Medicine and Community Health, Tufts University School of Medicine, Boston, MA
John L. Durant, PhD, PE , Department of Civil and Environmental Engineering, Tufts University, Medford, MA
Benjamin Bostick, PhD , Department of Earth Sciences, Dartmouth College, Hanover, NH
Joshua D. Landis, BA , Department of Earth Sciences, Dartmouth College, Hanover, NH
Christine George , Department of Geological and Environmental Sciences, Stanford University, Stanford, CA
Tommy Rock, BA , Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, AZ
Johnnye L. Lewis, PhD, DABT , Community Environmental Health Program, SW Center for Environmental Health COEP, University of New Mexico Health Sciences Center, College of Pharmacy, Albuquerque, NM
The Church Rock Chapter in the Eastern Agency of the Navajo Nation is disproportionately burdened by 33 documented abandoned mine sites. Extraction and processing of uranium ore left piles of contaminated waste exposed to the environment, impacting sediment, soil, and water on Navajo land. In addition, highly erodible, uranium-rich exposed rock formations may provide a natural source for mobilization.

To characterize the geochemical controls on uranium mobilty, a field and laboratory campaign was designed to support the Diné Network for Environmental Health; a community based participatory research collaborative which aims to identify whether exposure to uranium is associated with the prevalence of kidney disease among the Navajo. Incorporation of the field and experimental data with self-reported exposure and ultimately with direct measurement of biomarkers for kidney disease will form the exposure assessment of the multi-level risk model of the relationship between kidney disease and uranium exposure.

Water, sediment, and vegetation samples were taken during the wet season, when episodic, flashy precipitation was anticipated to provide the most potential for uranium mobilization. Concentrations of uranium in surface water downstream of mining locations and waste deposits were not detectable and average downstream sediment and vegetation concentrations did not exceed background. Sediment samples with elevated uranium appear to be associated directly with mine material. Further characterization of mine waste material suggests uranium is highly soluble, resulting in relatively rapid dissolution and removal during precipiation events. Preliminary modeling results using these data in combination with survey results will be presented.

Learning Objectives:
1. Understand the spatial and geochemical picture of uranium in the Church Rock Mining District. 2. Learn about methods used to incorporate environmental data into exposure assessment. 3. Complete a “first pass” semi-quantitative look at risk modeling results using these data.

Keywords: Uranium, Environmental Exposures

Presenting author's disclosure statement:

Any relevant financial relationships? No
Any institutionally-contracted trials related to this submission?

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.