uranyl-fluoride and uranium-hexafluoride

Urinalysis measurements from 31 workers acutely exposed to uranium hexafluoride (UF6) and its hydrolysis product UO2F2 (during the 1986 Gore, Oklahoma UF6-release accident) were used to develop a modified recycling biokinetic model for soluble U compounds. The model is expressed as a five-compartment exponential equation: yu(t) = 0.086e-2.77t + 0.0048e-0.116t + 0.00069e-0.0267t + 0.00017 e-0.00231t + 2.5 x 10(-6) e-0.000187t, where yu(t) is the fractional daily urinary excretion and t is the time after intake, in days. The excretion constants of the five exponential compartments correspond to residence half-times of 0.25, 6, 26, 300, and 3,700 d in the lungs, kidneys, other soft tissues, and in two bone volume compartments, respectively. The modified recycling model was used to estimate intake amounts, the resulting committed effective dose equivalent, maximum kidney concentrations, and dose equivalent to bone surfaces, kidneys, and lungs.

Topics: Accidents, Occupational; Environmental Exposure; Fluorides; Humans; Hydrofluoric Acid; Models, Biological; Tissue Distribution; Uranium; Uranium Compounds

Nineteen UF6/UO2F2 inhalation studies were undertaken in purebred, female beagle dogs (N = 16) to examine inter alia, (a) the possible relations of exposure, whole body, lung and renal uranium levels to excretion rates; (b) the threshold U6+ dose and renal concentration for renal injury; (c) the distribution and retention functions for U6+ in major tissues; (d) biochemical indicators of renal injury; and (e) aspects of U-induced tolerance. Each of these issues was investigated in the context of the chemical toxicity of U6+ following brief exposures to 235UO2F2 in the presence or absence of HF (the decomposition products of 235UF6). Both gamma-(235U) and alpha-(234U) counting methods were applied. In nine studies on 5 dogs, UO2F2 was administered intravenously. The major findings from both types of studies include: (1) UO2F2 retention time in the lungs is shorter than for UO3 or uranyl nitrate, viz. greater than 80% translocated with T 1/2 of less than 20 min; (2) the urinary elimination of U6+ follows closely to the ICRP excretion equation; (c) an absorbed dose of approximately 10 micrograms U6+ kg-1 body weight appears to be effective in producing renal injury; (d) a renal concentration of 0.3 micrograms g-1 kidney is close to a threshold concentration for renal injury; and (e) urinary and blood biochemical changes and histopathologic data were acquired and evaluated in both novice and tolerant animals. This report, considers all of these objectives and findings: Those involving biochemical indices and uranium-induced tolerance will be more fully reported elsewhere. In general, the dog studies attest to the usefulness of the intravenous human studies for certain U6+ dose-response data and interface well with new retention data on intravenous uranyl citrate in dogs by Stevens et al.

Topics: Aerosols; Animals; Body Burden; Dogs; Feces; Female; Fluorides; Injections, Intravenous; Kidney; Lung; Tissue Distribution; Uranium; Uranium Compounds