Integrating uranium geochemistry, geographic information systems, and risk modeling: An interdisciplinary & participatory approach to assess the environmental and human health impacts of uranium mining on the Navajo Nation

Since the 1940's, the Navajo Nation has been impacted by uranium exploration, mining, and processing to supply the United States with nuclear weapons and power. After the boom of uranium extraction in the 1950's, followed by a subsequent bust in the late 1980's, widespread environmental pollution was left behind. A lack of environmental and community health information prompted the formation of a multidisciplinary community based participatory research partnership known as the Dine Network for Environmental Health (DiNEH). The goal of the DiNEH project is to investigate the environmental, health, socioeconomic, and cultural risk factors contributing to kidney disease and/or diabetes in the Eastern Agency of the Navajo Nation in New Mexico. The most sensitive health endpoint for uranium exposure is its nephrotoxicity, suggesting that uranium exposures could be contributing to the 3-fold increase in chronic kidney disease among the Navajo compared to the general U.S. population.;This thesis addresses the hypothesis that uranium exposures may be contributing to increased kidney disease among the Navajo. The objectives of this investigation were to (1) characterize the geochemistry of uranium in sediment to determine sources, transport mechanisms and mineralogy governing mobility and toxicity, (2) combine these data with DiNEH health survey information using GIS-based thematic mapping to communicate and manage exposure risk, and (3) integrate environmental and geospatial exposure variables with self-reported exposure information from the health survey in a multi-level risk model for kidney disease and diabetes to determine which exposures act as significant predictors of kidney problems.;Sediment uranium concentrations (n=200) were lower than expected and within background range (3-8 mg/kg) with the exception of samples collected near a uranium waste pile (>100 mg/kg). Characterization of uranium in contaminated samples revealed highly soluble uranyl silicate minerals which dissolve rapidly when in contact with pore water, reaching concentrations up to 4.0 mg/l. These data were used, along with water quality data in producing soil use-restriction and water hauling use-recommendation maps, written in both English and Navajo that will be widely disseminated throughout the Navajo Nation. Opinion-survey results suggest that the Navajo people find the maps to be a more effective means of disseminating risk information compared to previous methods used in their communities. Logistic regression modeling of environmental, geospatial, and health survey data selected 6 variables (i.e., comorbidities, body mass index, the years of self-reported environmental exposures, education, family history of kidney problems, and living within a ½-mile of a mine shaft) as being statistically significant predictors of kidney disease and/or diabetes. These results are the first to demonstrate that environmental exposures including self-reported contact with contaminated material and proximity of one's residence to mining areas are predictive of kidney disease and/or diabetes. These findings emphasize the necessity for the development of risk management and remedial strategies to minimize exposures in mining impacted areas of the Navajo Nation.