Hisao Kawamura

Reference Japanese Man-ii. Distribution of Strontium in the Skeleton and in the Mass of Mineralized Bone

AbstractThe distribution of stable strontium concentration in different bones, as well as in a single bone, was studied. Dependence of the stable strontium-to-calcium ratio upon age was observed. A non-uniform distribution of the stable strontium to calcium ratio was found in both the skeleton and t

Reference Japanese man--I. mass of organs and other characteristics of normal Japanese.

The weight of organs measured from autopsy cases of normal Japanese adults, children, and infants is presented for the purpose of approaching a Reference Japanese Man. The skeletal content and the daily intake of alkaline earth elements are given. The lower rate of transfer ( K 2 ) to the thyroid gland of ingested radioiodine, as well as the remarkably shorter biologist half-life than the data adopted by ICRP, is also proved as a result of this study.

Determination of237Np in environmental samples using inductively coupled plasma mass spectrometry

A new analytical technique using ICP-MS was applied to the determination of237Np in some environmental samples. The accuracy and precision of the new method were assessed by comparison with those of conventional NAA and α-spectrometric method as well as by analysis of the intercomparison sample of Ravenglass NRPB silt. The results obtained by ICP-MS were in good agreement with those by NAA or α-spectrometry at a relative deviation of 2–9%. The detection limit is 0.02 mBq/ml (26 mBq=1 ng).

FALLOUT RADIOACTIVITY IN SOIL AND FOOD SAMPLES IN THE UKRAINE : MEASUREMENTS OF IODINE, PLUTONIUM, CESIUM, AND STRONTIUM ISOTOPES

To estimate the level and distribution of fallout attributable to the 26 April 1986 Chernobyl nuclear power station accident in the Ukraine, we sampled several kinds of substances at Korosten, Zhitomir and at Katyuzhanka, Vishgorod, Kiev in the Ukraine, and measured the radioactivity of 137Cs, 134Cs, 90Sr, 129I, 238Pu, 239,240Pu, and the density of 127I (stable). The substances investigated were soil, dry milk, wheat, rye, drinking water, and mushrooms. Except for the mushrooms collected, which were sampled at Katyuzhanka, Vishgorod, and at Kiev, all substances were at Korosten, Zhitomir. The activity of 137Cs, 134Cs, 90Sr, 238Pu, and 239,240Pu were all higher in soil and mushrooms than in the other four substances. The activity of 137Cs was 960 and 1,210 Bq kg-1 in the two soil samples and 6,110 Bq kg-1 in the mushrooms. The activity of 134Cs was approximately 15% of 137Cs in the two soil samples while < 3% of 137Cs in the mushrooms. The activity concentration level of 90Sr as compared to 137Cs concentration was 15-31% in food samples other than mushrooms but only 1.9% in mushrooms and 1.4 and 1.2% in the two soil samples. The radioactivity ratios, 238Pu: 239,240Pu and 239,240Pu: 137Cs, suggested that the proportion of cesium radioisotopes and 239,240Pu in the soil attributable to the Chernobyl accident was approximately 100% and 10-20%, respectively, while approximately 100% of 239,240Pu in the mushrooms was attributable to the accident. The activity of 129I was small but the ratio of 129I: 127I in the two soil samples was 4.3 x 10(-8) and 1.0 x 10(-7), which is approximately 10 times larger than that in the global fallout. These results suggest that the areas where the soil was sampled are iodine-deficient and were contaminated slightly by the Chernobyl accident.

Dietary intakes of seven elements of importance in radiological protection by asian population: comparison with ICRP data.

Abstract— Within the framework of a Coordinated Research Project (CRP) organized by the International Atomic Energy Agency, Vienna, the daily dietary intakes of seven elements by adult populations living in nine Asian countries were estimated. The countries that participated in the study were Bangladesh, China, India, Indonesia, Japan, Pakistan, Philippines, South Korea (Republic of Korea, ROK), and Vietnam and together they represented more than half of the world population. The seven elements studied were calcium, cesium, iodine, potassium, strontium, thorium, and uranium. These elements have chemical and biological similarity to some of the radionuclides abundantly encountered during nuclear power production and therefore data on these elements could provide important information on their biokinetic behavior. Analyses of diet samples for these seven elements were carried out using highly sensitive and reliable analytical techniques. One thousand one hundred and sixty analytical determinations were made on two hundred and twenty samples of typical diets consumed in these countries to estimate the daily intakes of these elements by the adult Asian population. The median daily dietary intakes for the adult Asian population were found to be 0.45 g calcium, 7 μg cesium, 90 μg iodine, 1.75 g potassium, 1.65 mg strontium, 1 μg thorium, and 1 μg uranium. When compared with the intakes proposed for ICRP Reference Man by International Commission for Radiological Protection, these intakes were lower by factors of 0.41 for calcium, 0.7 for cesium, 0.45 for iodine, 0.53 for potassium, 0.87 for strontium, 0.33 for thorium, and 0.52 for uranium. The lower daily intakes of calcium, cesium, and iodine by Asian population could be due to significantly lower consumption of milk and milk products, which are rich in these elements. The significantly lower intake of calcium in most of the Asian countries may lead to higher uptake of fission nuclide 90Sr and could result in perhaps higher internal radiation dose. The use of highly sensitive and reliable analytical methods resulted in accurate and lower intake values obtained for thorium and uranium, which suggest that radiation dose from their ingestion at natural background levels is likely to be lower than what may be concluded from ICRP data.

Daily intake of 11 elements in relation to reference Japanese man

Diet samples were collected by a duplicated portion method from 31 locations in Japan in both the summer and winter of 1981. The ashed samples were analyzed with an inductively coupled plasma atomic-emission spectrometer (ICP-AES) for 11 elements: Na, K, P, Ca, Mg, Zn, Mn, Al, Sr, Cu and Ba. Average daily intake was as follows: Na--4.5 g, K--1.9 g, P--0.92 g, Ca--0.56 g, Mg--0.20 g, Zn--7.1 mg, Al--4.0 mg, Mn--3.4 mg, Sr--2.3 mg, Cu--1.3 mg and Ba--0.36 mg. A tendency for higher mineral intakes was found in central Japan. These were the highest in the Chubu area followed by the Kanto and Kinki areas. Lower mineral intakes, below the averages for Japan, were found in western Japan, especially in the Chugoku and Shikoku areas. Daily intake of most elements, except Na, Mn, and Sr, was found to be 40-70% of the levels of Reference Man, which were reported by International Commission on Radiological Protection (ICRP) for the Western Europeans and North Americans. Daily intake of Na, Mn and Sr was almost the same in both cases.

Intercomparison of INAA and ICP-MS results for thorium determination in Pakistani diet.

A pilot study on ingestion and organ content of trace elements of importance in radiological protection was to be carried out in Pakistan. Baseline analytical data on daily dietary intake of thorium was to be measured using Instrumental Neutron Activation Analysis (INAA) technique. To determine the accuracy and reliability of our technique, some samples were measured in Pakistan using INAA and in Japan using Inductively Coupled Plasma-Mass Spectrometry. For intercomparison of results overall mean Z-scores were calculated. The results showed validity of our technique. Mean value of 232Th concentration in Pakistani diet samples using INAA technique is 0.0062 +/- 0.0028 microg/g and with ICP-MS technique is 0.0069 +/- 0.0032 microg/g.

Actinides concentrations in human tissues.

Fallout 239,240Pu concentrations in some autopsy tissues from the general population in Japan are described. Body burden and relative distribution among tissues of plutonium were obtained by extrapolating using the mass of relevant tissues of the normal Japanese adult. 239,240Pu-to-90Sr body burden ratio was obtained. ICRP models were used to estimate body burden and relative contribution of ingestion intake. Need for data on the intraskeletal distribution of fallout plutonium and more information on gastrointestinal absorption in man was stressed.

Analytical Quality Assurance Procedures Developed for the IAEA's Reference Asian Man Project (Phase 2)

Analytical quality assurance procedures adopted for use in the IAEA Co-ordinated Research Project on Ingestion and Organ Content of Trace Elements of Importance in Radiological Protection are designed to ensure comparability of the analytical results for Cs, I, Sr, Th, U and other elements in human tissues and diets collected and analysed in nine participating countries. The main analytical techniques are NAA and ICP-MS. For sample preparation, all participants are using identical food blenders which have been centrally supplied after testing for contamination. For quality control of the analyses, six NIST SRMs covering a range of matrices with certified and reference values for the elements of interest have been distributed. A new Japanese reference diet material has also been developed. These quality assurance procedures are summarized here and new data are presented for Cs, I, Sr, Th and U in the NIST SRMs.

Contents of cesium, iodine, strontium, thorium, and uranium in selected human organs of adult asian population.

Contents of cesium, iodine, strontium, thorium, and uranium in some selected human organs were estimated for adult Asian population using data obtained in four Asian countries: China, India, Philippines, and Republic of Korea, as part of a Coordinated Research Program of the International Atomic Energy Agency on “Ingestion and Organ contents of elements of importance in radiation protection.” These countries together represent more than 40% of the world population. Highly sensitive analytical techniques were employed to measure cesium in skeletal muscle, iodine in thyroid, strontium in skeleton, thorium and uranium in skeleton, liver, kidneys, and lungs where, in comparison to other organs, these elements are present in higher concentrations. The organ contents for adult Asian population, when compared with the corresponding data proposed for Reference Man by International Commission on Radiological Protection (ICRP), showed about 40 times lower kidneys content and about 10 times lower skeleton content of uranium. The content of thorium in skeleton for Asian population was also half of the ICRP Reference Man value. Interestingly, organ contents for the other elements such as iodine in thyroid, cesium in skeletal muscle, and strontium in skeleton were comparable for Asian and the Caucasian population (represented by ICRP Reference Man). Organ contents for these elements were also calculated by applying the new ICRP models of these elements to their daily intakes. The comparison of the calculated and measured organ contents showed that despite uncertainties in the organ content values arising due to the inter-country variations in daily dietary intakes, the contents were within a factor of two to three. This observation is significant since human data both on organ contents and ingestion were obtained at environmental level of intakes. The study suggests that currently available ICRP models for these elements are quite realistic.