Depleted Uranium in Soil and Dust Near the NL Industries Site, Colonie, New York

Depleted uranium (DU), a by-product of the uranium enrichment process, is chemically toxic and radioactive. From 1958 to 1981 DU was used to manufacture munitions and aircraft counterweights at the NL Industries site in Colonie, NY. Waste material was burned and emitted from a smokestack as fine particles of DU oxide. In total, between 5 and 10 metric tons of DU settled from the air on soil, rooftops, and other surfaces near the plant during its operations.

Following final closure of the plant in 1984, the US Dept. of Energy and the Army Corps of Engineers removed the factory building and many tons of soil on the plant site and surrounding properties that were above the negotiated cleanup standard of 35 picocuries per gram. The Army Corps declared the cleanup completed in the fall of 2007.

In 2006, several soil and dust samples were collected on three residential and one commercial property near the plant site. Soil samples were collected from yards and dust samples from interior surfaces. None of the soil samples exceeded the NL site cleanup standard. However, more than one half of the dust samples were significantly above the cleanup standard, with at least one sample from each property exceeding the standard. One dust sample was ten times higher than the NL site standard.

Contaminated dusts contain microscopic DU particles which have the potential to be re-suspended and inhaled by building occupants in the course of normal day-to-day activities. Once inhaled, the particles are retained in the lung where they can potentially damage surrounding lung tissue. The particles will gradually dissolve and DU will spread to the liver, kidneys, and other organs before being excreted. Present day urinary excretion levels of DU in exposed residents and workers indicates that some of the particles dissolve very slowly. Studies are ongoing to determine the size and chemical makeup of the DU particles to improve predictions about how they will behave in the environment and inside the bodies of contaminated individuals.

It is clear that contaminated dusts represent a potential pathway for secondary exposure to DU particles. Systematic sampling of household dust in all the surrounding properties is necessary to understand the extent of contamination in order that appropriate remedial action can be taken.