Measurements of the whole-body content of 241Am and its distribution in the body were made at 8, 10 and 12yr following inhalation of the insoluble dioxide by a worker in 1%5. Chelation therapy was administered at another center from 1%7 to 1974 and excretion of over one-half the initial body burden of 2.1 pCi (77.7 kBq) was obtained. Since the cessation of therapy, a very slow decrease in body content was observed indicating a retention half-time of more than I 0 0 yr.Longitudinal profile scans showed that the distribution of activity in the body remained essentially the same from 1973 to 1977. About one-fourth of the total body burden was in the chest region, and transverse profile scans of the chest showed that the majority of activity in that region was in the lungs; a slight decrease in the lung content was observed. The distribution of activity in the skeleton was extremely well correlated with the distribution of available bone surface area.An increase in the ratio of counts obtained from the liver region to those from the left side of the abdomen since the chelation therapy was halted indicated that there was redistribution of activity still taking place. The amount of activity translocated to the liver may justify the resumption of chelation therapy in the future.
Alpha-particle spectrograms of bone samples from USTUR Case 246 were analyzed to determine the depth in tissue from which the 241Am alpha-particles were emitted. In four samples of bone, the lack of energy straggling in the alpha spectra indicated that essentially all the 241Am was deposited directly on the exposed bone surface, and none had been translocated to within bone volume. These findings agree well with the results of autoradiographic examination of bone samples from the same case, but are in marked contrast to findings on another case (USTUR Case 102) who had been exposed to a much smaller amount of 241Am at a younger age and survived approximately twice as long after the exposure. It is problematical whether the lack of 241Am redistribution, and therefore the implied absence of bone remodeling, in Case 246 was due to his advanced age at exposure or to a deterministic effect of alpha-irradiation on bone metabolism, but the observation of radiation effects on bone metabolism in former radium workers supports the latter.
The concentration of plutonium has been determined along the length of the hair of a female subject who received 11 kBq (0.3 pCi) of 239Pu by intravenous injection in 1945. The subject succumbed to her pre-existing illnesses 518 days post injection, and her remains were exhumed in 1973.The subject's hair, 280 mm in length for the longest strands, was divided into 20-mm long sections and the plutonium concentration in each was determined. The concentration ranged from 22 Bq/kg (0.59 pCilg) at the distal end to 3 Bqlkg (0.08 pCi/g) at the proximal end (nearest the scalp). The distance of each section from the scalp was then converted to an estimated time in days post injection by applying the growth rate of the hair indicated for this individual.The plutonium concentration as a function of time could be well-fitted (in the least-squares sense) by either of two functions. The first function was the sum of a single exponential, whose half-time was 81 f 16 days, plus a constant term. This half-time corresponded to that found for the longest-lived of five components of the plutonium concentration in the blood of other individuals in the same series of injections, i.e. 88 2 13 days (Du72). The second function which fitted the hair data was the sum of two exponentials, whose half-times were 32 k 18 and 260 f 80 days, respectively. These values overlap the half-times of 42 and 300 days found for components of the urinary excretion of plutonium by man (Du72). This agreement is expected in view of the correspondence of the hair and blood data, since urine is a plasma filtrate. The possible use of hair as a bioassay material for plutonium in man is suggested.
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