Two complementary experiments were performed to estimate the retention and gross distribution of radioisotopes of tungsten in the rat. The first experiment involved the measurement of 187W in urine, feces, blood, plasma, GI tract, and residual carcass of 24 rats over a 3-day period. The second experiment involved the distribution and retention of 185W in major organs of 70 rats over periods of up to 254 days. The radiotungsten was administered by gavage in 1 ml of tungstate solution at pH 8 to adult Wistar rats. Urinary and fecal excretion each accounted for approximately 40% of the administered dose after 24 hr. Long-term studies of 185W disclosed that after 100 days, greater than 99% of the total body burden (about 0.4% of the administered dose) was retained in bone with a biological half time of I 100 days for the slowest component of a three-component elimination curve. This half time appears to be longer than previous studies have reported, indicating that bone may be the primary site of damage from long-term retention of 181W and 185W. Elimination from soft tissues was relatively rapid with highest concentrations during the first week in the following tissues: spleen, hair, kidney, uterus, liver, prostate, and ovary.
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S.V. Kaye (1968) studied this question.