[en] The retention of ²⁴¹Am in mice 48 h after administration by gavage is reported here. The ²⁴¹Am was given to mice in the form of either ²⁴¹Am nitrate or ²⁴¹Am citrate. The ²⁴¹Am was also injected into rats in the same form. The homogenized livers of those rats were subsequently administered by gavage to another group of mice. The retention of ²⁴¹Am citrate was 1.5 X 10(-2)% of the original dose and was the highest among the compounds examined. The retention of biologically incorporated ²⁴¹Am into the liver as ²⁴¹Am nitrate and as ²⁴¹Am citrate was 2.4 X 10(-3) and 2.6 X 10(-3)%, respectively, and was similar to the retention of ²⁴¹Am nitrate, which was 2.8 X 10(-3)%. The ratio of the retention in the carcass to that in the liver for the ²⁴¹Am citrate was lower than that of the ²⁴¹Am nitrate and the biologically incorporated ²⁴¹Am. This difference indicates that the distribution of ²⁴¹Am in the animal body depends on the chemical form administered. The retention of liver-incorporated ²⁴¹Am as citrate after autolysis of the liver is similar to that of fresh liver-incorporated ²⁴¹Am citrate

[en] The placental transfer and distribution of ²⁴¹Am in the feto-placental system were studied in pregnant rats. Rats were injected intravenously with ²⁴¹Am citrate at 15 or 18 days of gestation. Groups injected at 15 days of gestation were sacrificed 2, 24, 48, or 120 hr after injection, and the group injected at 18 days was sacrificed 24 hr after. The radioactivities of ²⁴¹Am in fetus, fetal membrane, and placenta were determined, and its distribution in the feto-placental system was investigated by high-speed autoradiography using a silver-activated zinc sulfide-coated membrane as an intensifying screen. The deposition of ²⁴¹Am in feto-placenta units increased with the number of days of gestation. Results of autoradiography revealed that major deposition sites of ²⁴¹Am in the fetus are the skeleton and liver. Heavy deposition of ²⁴¹Am in the yolksac splanchnopleure and its existence in the exocoelom strongly suggest that the yolk sac placenta plays an important role in the placental transfer of this nuclide

[en] The concentrations of ^239+240Pu and ²⁴¹Am in the debris from the second thermonuclear test detonation of the USA (Bravo) were determined. This debris, called Bikini Ash, was collected in 1954 on the deck of the Japanese fisherboat '5th Fukuryu-Maru' which was located some 150 km to the east of Bikini Atoll at the time of the thermonuclear test. A portion of the 1954 sample was subjected to analytical analysis in 1974. The concentrations of ^239+240Pu and ²⁴¹Am in th sample were determined to be 25.9 + - 1.7 and 12.9 + - 0.9dis/min/mg, respectively. From these values, the ratio of ²⁴¹Pu/^239+240Pu at time zero was calculated to be 26 + - 3, and this ratio was almost the same as in the Mike thermonuclear debris. ^239+240Pu and ²⁴¹am contents of the marine sediment samples collected near Bikini Atoll were also analyzed, and a significant contamination with these nuclides was found to be still remaining in this area. (author)

[en] The direct transfer of organically-bound ³H (OBT) of diet to that in the human body is reasonable, since the human body needs essential amino acids and fatty acids. Metabolic models of ³H which were recently developed for the human body took this direct incorporation into account. Data for fallout ³H in diet and human tissues were used to validate model parameters, although such data are relatively scarce. However, a simple equilibrium between dietary ³H and human body ³H was assumed for such validations. The simple equilibrium assumption means completely neglecting past ³H concentration in the human body. When the model consists of compartments which have long mean residence times, estimated ³H concentrations in the human body from the simple equilibrium assumption can differ significantly from results of adequate calculation considering contribution of past human ³H concentrations. The examples of such calculations are described in this paper. Results of the calculations show that suitable environmental ³H transfer models are necessary to use fallout ³H data for the validation of ³H metabolism models. (author). 24 refs., 9 figs

[en] Ingestion intakes of fallout Pu throughout Japan in the 1959-1962 and 1978-1980 periods were measured by analyzing composite samples of each foodstuff or duplicate composite food samples consumed by five persons for a period of 1 d. Cumulative ingestion intake in Tokyo for the period from 1954-1980 was estimated by regression analysis. The cumulative ingestion intake, calculated by simple regression analysis between the natural log of the intake and that of annual fallout deposition of Pu, was estimated to be 450 pCi. Calculated by a multiple regression analysis, including the natural log of annual fallout deposition rates for a previous year as an additional independent variable, it was estimated to be 600 pCi. Considering in combination an ingestion intake, the value of which is calculated by the multiple regression analysis; an absorption ratio from the gastrointestinal tract of 0.001 (a recently reported value for low-level soluble Pu independent of chemical form); and the metabolic model in ICRP Publication 30, it is possible to estimate that the contribution of ingestion intake to liver and bone burden would be approximately 30%

[en] The ingestion of fallout Pu from seven or six separate food groups collected in Japan during 1962 and 1983-84 are reported. The contribution of ingested Pu from algae was the highest among the food groups studied: approximately 60% of the total ingested Pu during 1962, and 74% in 1983-84. The contribution from whole marine products, i.e. algae and fish/shellfish, was approximately 70% of the total Pu ingested in 1962, and more than 90% in 1983-84. The higher Japanese ingestion rate than that of the United States is attributable to the higher consumption rate of marine food products in Japan. Also reported in this paper are the ingestion rate for ¹³⁷Cs from fallout through the same food groups, and the concentration of Pu and other radioactive nuclides in specific individual foodstuffs and algae samples

[en] The ²²²Rn concentration in outdoor workplaces were measured in Aomori Prefecture, Japan as a part of a program on measurement of natural radiation background dose to people in the prefecture where Japan's first nuclear fuel cycling facilities are now under construction. ²²²Rn concentrations were measured in 116 outdoor workplaces by passive Rn detectors for 10 months, which represented agricultural, forestry, fishery and construction/transportation workplaces. The ²²²Rn concentrations in outdoor workplaces were generally lower than those in indoor environments. The dose to workers was estimated by using the results of the passive detectors as well as diurnal variation of ²²²Rn and equilibrium factor measured with active-type detectors. The average dose from ²²²Rn and its progenies to people in Aomori Prefecture was estimated as 0.39 mSv x y^-1 based on the obtained results and results in indoor environments. The contribution of ²²²Rn in outdoor workplaces to the total dose was 3.3% because of low occupancy ratio. (author)

[en] A new technique for the determination of the isotopic ratio of ²⁴⁰Pu/²³⁹Pu is proposed. The U L X-rays are emitted from plutonium isotopes with the internal conversion of gamma-transition following alpha decays. The technique is based on the different emission ratios of the U L X-rays to alpha-rays between ²³⁹Pu and ²⁴⁰Pu. A system capable of simultaneously counting of U L X-rays and alpha-rays was constructed by using a low energy photon spectrometer and a Si(Au) surface barrier detector for the measurement of X-rays and alpha-rays, respectively. The ratio of ²⁴⁰Pu/²³⁹Pu for two environmental samples was estimated by this method. (orig.)

[en] To study fallout ³H ingestion in Japan, 16 separate food group samples were collected from Akita during 1985. The ³H concentration in free water and that in a tissue-bound form were determined separately. The average ³H concentration in the tissue-bound form was 2.2 Bq L-1, 1.7 times higher than in the free water of the food. The ingestions of ³H in the tissue-bound form and as free water in the diet were 0.60 Bq d-1 and 1.0 Bq d-1, respectively. Cereals represented the food group that contributed the most to the ingestion of tissue-bound ³H. Total ³H ingestion was estimated to be 4.1 Bq d-1. The contribution of the tissue-bound form to the total ingestion was 15%, considerably lower than reported for Italian diets. The ratio of ³H ingestion in the tissue-bound form to the free water form in the diet was similar to the ratio reported for New York City

[en] Americium and plutonium concentrations in food samples and human tissue samples were determined using alpha-ray spectrometry. The objectives of this study were to establish the present ingestion level of ²⁴¹Am, to know the level of ²⁴¹Am in the human body, and to estimate a metabolic parameter usable with the ICRP metabolic model. This report describes the concentrations of ²⁴¹Am and ^239+240Pu in both food samples collected in 1985 and 1986, and in human tissue samples of Japanese who died between 1981 and 1984. An estimation of the half-life of Am in the liver using the ICRP metabolic model is also made. (author) 30 refs.; 13 tabs