Absorption and Retention of Uranium From Drinking Water by Rats and Rabbits

Abstract

Uranium in the form of uranyl nitrate hexahydrate was administered in drinking water to Sprague-Dawley rats for periods of 28 and 91 d and New Zealand White rabbits for 91 d. The animals consumed food and water ad libitum. Subgroups of rabbits were followed for recovery periods of up to 91 d; 24-h collections of urine and feces were performed for some of the rabbits at various times during the exposure and recovery periods. At the end of the experiment, all animals were sacrificed and femur and kidney samples were analyzed for uranium residues. The results show that both rats and rabbits absorb about 0.06% of ingested uranium in the gastrointestinal (GI) tract. The distribution and retention of uranium in the skeleton and kidneys of rats are comparable to parameters reported for humans. The retention half-time in rabbit bone is substantially longer than for humans. The implications of extrapolating from animal data to effects on humans are discussed.

Uranyl Nitrate—Induced Proximal Tubule Alterations in Rabbits: A Quantitative Analysis

“…The amounts of uranium accumulated in the kidney and femur of exposed rabbits in the present work have been reported (26) and are in accord with those published in the literature (16,20). Briefly, our results indicated a large increase in the amount of uranium in both the kidney and femur of the rabbits in the high-dose group and smaller increases in the amount of uranium in the low-dose group.…”

“…Vacuoles in the cells increased in size but decreased in number with increased recovery period following exposure to UN, which, according to earlier studies, is due to the fusion of small vacuoles to form the large ones (4,18,26). Vacuolization has been suggested to represent an early sign of altered metabolic activity in the cell (24).…”

“…Vacuolization has been suggested to represent an early sign of altered metabolic activity in the cell (24). Uranium alters the permeability of cell membranes, thus disturbing fluid transport that results in increased fluid uptake by the cell (26 (4,18,27). Large lysosomal elements with their decreased numbers possibly is a result of fusion of small ones (8).…”

“…Such changes can lead to a decreased glomerular filtration rate by disturbing fluid transport across the cells (3). The extent of lumen debris would indicate the severity of necrosis and sloughing (26).…”

Baseline risk assessment of ground water contamination at the uranium mill tailings site near Salt Lake City, Utah. Revision 1

“…Uranium retention in bone consists of a short retention half-time of 20 days, followed by a long retention half-time of 5000 days for the remainder (Tracy et al, 1992).…”