Role of particle size in the evaluation of uranium hazards

The pattern of uranium deposition in the respiratory tract, which is determined primarily by size-related particulate properties is shown to be affected significantly by particle densities as large as those of the uranium oxides. The size distributions of pulmonary particulate deposits, estimated from pulmonary deposition curves for dense particles, are roughly lognormal and show modal logarithms in the aerodynamic size range of 0.2 to 3.0 μm. Solubility clearance constants, which are related to the size distribution of the pulmonary deposit, have been calculated for a number of human exposures. The results are discussed in terms of the significance of particle size