Destructive and non-destructive procedures have been developed for the determination of titanium by photon activation analysis.
The non-destructive analyses with an internal standard method are performed on niobium and tantalum oxides while destructive
determinations, including non-isotope addition and radiochemical separation, are applied to yttrium oxide samples.
The paper describes the recent plutonium measurements on tissues taken at human autopsy on foodstuffs collected in northern Japan. Estimates of plutonium concentrations are made using the ICRP 30 metabolic model and is compared with the results of our measurements.
Americium and plutonium concentrations in food samples and human tissue samples were determined using alpha-ray spectrometry.Food samples, representative of the average dietar intake over a period of 30d in Japan, were pruchased in Akita during 1985 and 1986. The food was divided into six groups: cereals, vegetable, fruits/beans, seaweeds, fish/shellfish, and meats/eggs/milk. Most of the. total ingestion of both Pu and Am was contributed by seaseed and fish/shellfish. The concentration of Am in the other food groups was low.A compoarison of the measured241Am/239+240Pu ratio in human liver with the predicted value of the ICRP-30 or ICRP-48 model showed that the half-life of Am in the liver is approximately 2–10y. The human tissue samples were obtained from subjects who died in Akita and Niigata Prefectures in northern Japan during 1981–1984. The median concentration of241Am was 1.4 mBq/kg-wet in the stemum (n=11), 3.4 mBq/kg-wet in the liver (n=19), and 0.5 mBq/kg-wet in the lung (n=15). The ratio of241Am/239+240Pu was 0.34 in the sternum, 0.12 in the liver, and 0.14 in the lung.
We investigated successfully the uptake of the radionuclides with short half-lives, such as 24Na, 28Mg, 43K and 47Ca, and the effect of stable Ca on their uptake in carrot (Daucas carotacv. U.S. harumakigosun) by the multitracer technique. These radionuclides were produced by a fragmentation reaction of Ti in a 135 MeV/nucleon 12C beam accelerated by the RIKEN Ring Cyclotron. This study shows that these radionuclides in a multitracer can be utilized in environmental research.
Authors:T. Furuki, R. Abe, H. Kawaji, T. Atake, and M. Sakurai
The phase transitions of α,α-trehalose dihydrate (Th) were investigated by either differential thermal analysis (DTA) with an in-house apparatus of variable-pressure type equipped
with an open sample holder or commercially available TG (thermal gravimetry)-DTA apparatus for comparison under the same experimental
conditions as to the heating rate (2°C min−1), the type of pan (open), and the particle size of Th (63 μm). The former DTA measurements were carried out under five different total pressures, 101, 75, 61, 48 and 35 kPa, which
provided quite helpful information necessary for confirmative assignments of the endothermic peaks due to either melting or
dehydration of Th. The usage of largely different amount of Th, 126 and 14 mg for the DTA and TG-DTA measurements respectively, led to their different DTA traces, showing that there were
largely different extents of the influence by the measured sample surface exposed to the surrounding atmosphere on its dehydration
behavior. In addition the high thermal sensitivity achieved with such mass of Th gave rise to an interesting discovery of an unidentified thermal event at 92°C prior to either melting or dehydration of
Authors:Y. Takizawa, S. Hisamatsu, T. Abe, and J. Yamashita
Radioactive fallout constitutes the major source of contamination of the environment with fission products. Our primary interest was in selected fission products, such as 131I, 89Sr, 90Sr, and 137Cs, and neutron activation products, such as 3H and 14C. Plutonium-239,240, 241Am and 90Tc are generated from nuclear tests, and they are important by-products of nuclear industries. Polonium-210, 210Pb and 232Th, 230Th and 228Th occur widely in nature. These radionuclides enter the human body through inhalation and the ingestion through food and water. These nuclides may cause radiation doses to certain organs of the body. Assessment of the resulting health hazards is an essential public health activity, which demands reliable techniques for the assay of the various radionuclides in man and his environment. In this paper, we present the accumulation of radionuclides from man-made sources and primordial radionuclides in various tissues of the Japanese population. The studies were performed at the Department of Public Health, Akita University School of Medicine, during the periods from 1973 to 1995.
Authors:Y. Takizawa, T. Abe, M. Yamamoto, and R. Yuan
Since 1962, we have been investigating the levels of239,240Pu in human tissues. In the 1960s, the quantities of239,240Pu found in the gonad and spleen were higher than those in liver and lung, as reported in our previous papers. This work was done to provide a reassessment of239,240Pu distribution among several tissue samples from the 1960s and early 1970s, using current analytical techniques for plutonium. The autopsy tissues were collected from the Hospital of Niigata Prefectural Institute for Cancer Research in Northern Japan from 1968 to 1975. The subjects were at least 50 years old at the time of death. The accuracy and precision of239,240Pu determinations were examined using NBS-SRM 4352 human liver samples. Our results are consistent with certified values.
Authors:Y. Takizawa, L. Zhao, M. Yamamoto, T. Abe, and K. Ueno
To determine the levels of210Pb and210Po in human tissues of people in Japan, various tissue samples were obtained at autopsy from the cadavers of 22 oncologic cases, mainly in Niigata Prefecture in northern Japan, from 1986 to 1988.Wet ashing, followed by electrochemical deposition and alpha spectrometry were used to separate and determine the210Pb and210Po present. Among the tissues analyzed, the highest concentrations of210Pb and210Po were observed in bone (sternum), liver, and kidneys. The total body burden of210Pb and210Po was found to be approximately 427 pCi and 514 pCi, respectively. This estimated210Po value did not differ significantly from values found in populations in the U.S.A. and European countries.
Authors:Y. Takizawa, H. Qingmei, S. Hisamatsu, and T. Abe
The concentration of232Th,230Th and228Th in various human tissues of Japanese subjects obtained at autopsies are reported. The tissue samples were weighed, spiked with234Th tracer and ashed by acid. The solution was dried on a hot-plate. Separation of thorium radionuclides was accomplished through cation-exchange resin chromatography and electrodeposition. The concentrations of thorium isotopes were measured by -spectrometry. Thorium-232 and230Th concentrations were found to be highest in lung, followed by bone. The maximum concentration of228Th was in bone. The lowest concentrations of thorium isotopes were in muscle.