Distribution of uranium in rats implanted with depleted uranium pellets

During the Persian Gulf War, soldiers were injured with depleted uranium (D U) fragments. To assess the potential health risks associated with chronic exposure to DU, Sprague Dawley rats were surgically implanted with DU pelle ts at 3 dose levels (low, medium and high). Biologically inert tantalum (Ta ) pellets were used as controls. At 1 day and 6, 12, and 18 months after im plantation, the rats were euthanized and tissue samples collected. Using ki netic phosphorimetry, uranium levels were measured. As early as 1 day after pellet implantation and at all subsequent sample times, the greatest conce ntrations of uranium were in the kidney and tibia. At all time points, uran ium concentrations in kidney and bone (tibia and skull) were significantly greater in the high-dose rats than in the Ta-control group. By 18 months po st-implantation, the uranium concentration in kidney and bone of low-dose a nimals was significantly different from that in the Ta controls. Significan t concentrations of uranium were excreted in the urine throughout the 18 mo nths of the study (224 +/- 32 ng U/ml urine in low-dose rats and 1010 +/- 8 7 ng U/ml urine in high-dose rats at 12 months). Many other tissues (muscle , spleen, liver, heart, lung, brain, lymph nodes, and testicles) contained significant concentrations of uranium in the implanted animals. From these results, we conclude that kidney and bone are the primary reservoirs for ur anium redistributed from intramuscularly embedded fragments. The accumulati ons in brain, lymph nodes, and testicles suggest the potential for unantici pated physiological consequences of exposure to uranium through this route.