Ecological Risk Assessment of Radiological Exposure to Depleted Uranium in Soils at a Weapons Testing Facility

Abstract

The potential for unacceptable risks to biota from radiological exposure to depleted uranium (DU) in soils was evaluated at two sites where DU weapons testing had been conducted in the past. A screening risk assessment was conducted to determine if measured concentrations of DU-associated radionuclides in site soils exceed radionuclide levels considered protective of biota. While concentrations of individual radionuclides did not exceed acceptable levels, total radionuclide concentrations could result in potentially unacceptable doses to exposed biota. Thus, a receptor-specific assessment was conducted to estimate external and internal radiological doses to vegetation and wildlife known or expected to occur at the sites. Wildlife evaluated included herbivores, omnivores, and top-level predators. Internal dose estimates to wildlife considered exposure via fugitive dust inhalation and soil and food ingestion; root uptake was the primary exposure route evaluated for vegetation. Total doses were compared with acceptable dose levels of 1.0 and 0.1 rad/day for vegetation and wildlife, respectively, with potentially unacceptable risks indicated for doses exceeding these levels. All estimated doses were below or approximated acceptable levels, typically by an order of magnitude or more. These results indicate that current levels of DU in soils do not pose unacceptable radiological risks to biota at the sites evaluated.

Depleted Uranium Mobility Across a Weapons Testing Site: Isotopic Investigation of Porewater, Earthworms, and Soils

“…Widespread use of depleted uranium (DU) munitions in regions such as the former Yugoslavia and the Middle East and, to a lesser extent, weapons testing in other parts of the world has left a legacy of environmental contamination. While several studies document the presence of DU contamination at weapons testing sites and in conflict zones − , important questions are yet to be answered concerning the long-term fate of DU in the environment and, in particular, how it might disperse from points of contamination. Therefore, the mobility of DU and its potential migration through the landscape, as well as its forms, associations, and bioavailability, are all key areas of concern.…”