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Kimberly A. Benson and Terry C. Pellmar
Radiation Pathophysiology and Toxicology Department
Armed Forces Radiobiology Research Institute, Bethesda, MD
The use of depleted uranium (DU) munitions during Desert
Storm resulted in a unique type of battlefield casualty, embedded DU fragments.
While there has been considerable research into the toxicity of acute
uranium exposure, the effects of chronic exposure to uranium from depleted
uranium fragments is unknown. The toxicity associated with embedded DU
may differ significantly from other chemical forms of uranium or other
routes of uranium administration. This study utilizes male and female
Sprague-Dawley rats and evaluates kidney, reproductive, behavioral and
neural toxicity associated with embedded DU pellets. Tissues are also
assessed for histological changes and for uranium content. DU doses are
manipulated by implanting varying numbers of pellets in the biceps femoris
of male and female rats. Uranium levels are high and dose-dependent in
kidney, urine, and bone. Despite high uranium levels in kidney, no renal
toxicity was evident in either male or female rats. Unexpectedly, uranium
was found in the brain of DU-implanted animals. Male rats were examined
for behavioral neurotoxicity and none was evident. However, in the hippocampus,
a brain area associated with memory, neuronal activity was different from
control in DU-implanted male animals. Reproductively, no effects of DU
were seen on the ability of the implanted female rats to get pregnant
or carry the litter to term. A correlation trend test revealed an increasing
trend of uranium levels in maternal kidney, placental tissue, and whole
fetus tissue with increasing levels of maternal DU implantation. This
effect was not seen in the fetal liver tissues. Measurements of maternal
gestational weight gain and food and water intake indicated no adverse
maternal effects. Litter parameters such as size of the litter, weight
of the pups and male:female proportions were also not affected by the
dose of DU. These data suggest that renal toxicity may be less of a hazard
than anticipated, but that cognitive deficits need to be considered. While
no reproductive toxicity was seen in the female rats, male rats have yet
to be examined for any alterations in reproduction due to the DU pellets.
Lack of reproductive and maternal toxicity in the female rat does not
preclude the possibility of problems with the development of the offspring,
an area of research which this laboratory is currently investigating.
Keywords: Depleted Uranium, Neurotoxicology, Reproductive
Effects
This work is supported by funds from US Army Medical Research
and Materiel Command.
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