Late excretion of plutonium following acquisition of known amounts

The urinary and fecal excretion rates of plutonium 10,000 days after intravenous injection of known amounts are compared with the predictions of various models. Both Langham's and Durbin's equations underestimated the urinary excretion by about an order or magnitude; the observed fecal excretion rates were also higher than the predictions. The total excretion rate predicted by the ICRP model was in quite good agreement with the observed rate, but it overestimated it at early times (<20 days). These differences are discussed. The increase in the excretion rate between 1500 days and 10,000 days is real, as shown by the increase in the estimate of body dontent of 239Pu of former Manhattan Project plutonium workers, as calculated from the measured urinary excretion and application of Langham's equation. In one of these subjects the urinary excretion rate started to increase at about 6000 days, reached a maximum at about 9500 days, and declined for the next 2700 days