Volume and
uranium content were determined in individual
urine voids over a 76-h (3.25-d) period from six unexposed normal male subjects and three male
uranium workers.
Uranium analyses were accomplished by a newly developed high-precision kinetic
phosphorescence analysis technique with a lower level of detection of 0.007 ng mL-1.
Urinary uranium concentrations in individual voids varied by a factor of 2 or less for any one unexposed subject, although there was an order of magnitude variation among the group of unexposed men. The fractional
urinary volume
excreted in the "standard" so-called simulated 24-h sample was the same for both the unexposed and exposed groups and averaged 0.42 +/- 0.13 of the total daily
urine volume. The fraction of
uranium in the simulated 24-h samples was 0.43 +/- 0.15 in the unexposed group but only 0.31 +/- 0.13 in the
uranium worker group, suggesting that the use of the simulated 24-h
urine sample would underestimate the total daily
urinary uranium output by approximately a factor of 2 in the
uranium workers. Daily
urinary excretion relative to intake from drinking
water (essentially equal to the
gastrointestinal uptake fraction) among the unexposed group ranged from 0.002-0.028,
averaging 0.011 +/- 0.008, with an indication that the
gastrointestinal uptake factor was inversely proportional to total intake via drinking
water.
