in Soil and Dust Near the NL Industries Site, Colonie,
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.