Shun'ichi Hisamatsu

Geographical distribution of cerebrovascular disease mortality and food intakes in Japan

The present study focuses on an analysis of the relationship between cerebrovascular disease mortality and food intake. For this purpose, standardized mortality ratios(SMRs) from cerebrovascular disease were calculated for 3341 basic administrative units (wards, cities, towns and villages) between 1969 and 1978 in Japan. The major nutrient intakes and 30 selected food items were obtained from the 1974-1974 Ministry of Health and Welfare, National Nutrition Surveys in 1040 randomly sampled census tracts in 600 areas (18% of the nation). Our analysis demonstrates that the geographical pattern of cerebrovascular disease SMRs in Japan vary from higher in East Japan to lower in the West, and higher in the less urbanized areas, and lower in the more urban ones. Foods positively associated with cerebrovascular disease were rice and other starchy foods, pork, algae (seaweed), and salty foods such as miso (soybean paste), pickled vegetables, soy sauce and salted fish. All of these foods, with the exception of pork, are part of the traditional Japanese diet. On the contrary, mortality was negatively associated with intakes of wheat, butter and margarine, beef and eggs, items considered to be representative of a European diet. Using a stepwise multiple regression analysis, miso and salted fish were selected as positive, and beef and eggs as negative correlates of cerebrovascular disease mortality. According to these results, it is suggested that these four foods are useful as negative and positive indicators of improvement in dietary intakes as related to the reduction in the occurrence of cerebrovascular disease.

Time-dependent changes of phytoavailability of Cs added to allophanic Andosols in laboratory cultivations and extraction tests.

Although it is well known that phytoavailability of radiocaesium is gradually lost after its deposition on the ground by fixation to soil minerals, the decreasing rates during early period after the deposition is not yet quantitatively evaluated. In this study, stable Cs was added to 5 types of soil, including Andosols, a sand-dune regosol and a smectic lowland soil, in a laboratory soil incubation experiment to assess the aging effect of radiocaesium. Aliquots of a soil sample were put into pots and incubated in an artificial climate chamber. Orchardgrass or red clover was cultivated for 28 d in soil pots containing one of the allophanic Andosol samples seven times during about 1200 d using new pots for each cultivation. The soil-to-plant transfer factors of Cs declined exponentially until about 100 d and were almost constant thereafter. The extractabilities of Cs by water and 1 M NH4OAc solution from this allophanic Andosol soil sample also decreased with time and their decreasing patterns were similar to that of the transfer factor. The temporal changes of extractabilities of Cs in other soil samples were also examined 6 times during about 600 d. Rate of decline for the extracted yield of the added Cs by 1 M NH4OAc varied widely among all the soil types. Two allophanic Andosol samples showed relatively higher extractabilities in comparison with the other soils throughout the incubation experiment, which may be attributable to the lower contribution of Cs specific sorption sites to total cation exchange capacity of the allophonic Andosol soil samples.

Effect of the counter anion of cesium on foliar uptake and translocation.

Direct deposition of radioactive material onto crops is one important pathway for safety assessment of radionuclides released from nuclear facilities. Foliar uptake of Cs by radish (Raphanus sativus L. cv. Redchim) was studied by applying droplets of Cs solution (CsCl or CsNO3) on an upper leaf surface. The uptake of Cs was strongly affected by counter anions of Cs in the applied solution. Approximately 80% of Cs was absorbed for CsCl solution, while only 20% was absorbed for CsNO3. The partition of absorbed Cs between leaf and root tuber was quite similar for both Cs compounds, which indicated that behavior of the absorbed Cs in radish was the same for both.

Plant induced changes in concentrations of caesium, strontium and uranium in soil solution with reference to major ions and dissolved organic matter

For a better understanding of the soil-to-plant transfer of radionuclides, their behavior in the soil solution should be elucidated, especially at the interface between plant roots and soil particles, where conditions differ greatly from the bulk soil because of plant activity. This study determined the concentration of stable Cs and Sr, and U in the soil solution, under plant growing conditions. The leafy vegetable komatsuna (Brassica rapa L.) was cultivated for 26 days in pots, where the rhizosphere soil was separated from the non-rhizosphere soil by a nylon net screen. The concentrations of Cs and Sr in the rhizosphere soil solution decreased with time, and were controlled by K+NH(4)(+) and Ca, respectively. On the other hand, the concentration of U in the rhizosphere soil solution increased with time, and was related to the changes of DOC; however, this relationship was different between the rhizosphere and non-rhizosphere soil.

Effect of Long-term Fertilizer Application on the Concentration and Solubility of Major and Trace Elements in a Cultivated Andisol

The concentrations and solubility of major and trace elements in soils collected from a field for long-term experiments maintained for more than 60 years and the neighboring area were investigated in order to reveal the influence of soil management on their behavior in soils. No obvious differences in the element concentrations in soils were observed except for P and U, whose concentrations were elevated in the surface soils of the experimented field because of the long-term application of phosphate fertilizers. Soil acidification associated with the successive applications of potentially acid fertilizers had changed the solubility of many elements as follows: the solubility of Li, Be, Al, Mn, Co, Zn, Y, Cd, Ba and rare earth elements increased, while the solubility of P, As, Se, Nb, Sb, Mo and V increased by liming. In the uncultivated soils, the concentrations of Fe, Zr, Nb, Hf and Th in the water extracts were relatively high, and a certain amount of these elements in the water extracts may occur in colloidal forms.

Increased prevalence of elevated serum IgE and IgG 4 antibodies in students over a decade

It is generally believed that asthma and other atopic diseases in children have been increasing in many industrialized countries over the last few decades. I Many researchers have repor ted the rise of the prevalence of such diseases as de termined f rom responses to questionnaires. These results, however, might be influenced by increased recognition of the disease by the general populat ion. We repor ted a corresponding increase in the prevalence of elevated specific IgE antibodies among students in a defined area in Japan since 1978. 2 It seems to be the only one -popu la t ion -based serologic study support ing the rise of atopic prevalence, which has been demonst ra ted by responses to questionnaires. The objective of this study was to obtain fur ther serologic evidence for this increase in atopy among students by measur ing serum IgG 4 and IgE antibody levels. IgG4 was chosen because it is well established that the existence of this kind of antibody reflects a subjects history of immunologic response to the relevant allergen. 3-5

Effects of radiocesium inventory on 137Cs concentrations in river waters of Fukushima, Japan, under base-flow conditions

To investigate the behavior of nuclear accident-derived (137)Cs in river water under base-flow conditions, concentrations of dissolved and particulate (137)Cs were measured at 16 sampling points in seven rivers of Fukushima Prefecture, Japan, in 2012 and 2013. The concentration of dissolved (137)Cs was significantly correlated with the mean (137)Cs inventory in the catchment area above each sampling point in both sampling years. These results suggest that the concentration of dissolved (137)Cs under base-flow conditions is primarily determined by the (137)Cs inventory of the catchment area above the sampling point. However, the concentration of particulate (137)Cs did not show a clear relationship with either the mean (137)Cs inventory or the dissolved (137)Cs concentration, thus indicating that particulate and dissolved forms do not effectively interact in rivers. To evaluate the contribution of the (137)Cs inventory within catchment areas, we analyzed relations between the (137)Cs concentration and the mean (137)Cs inventory over the area within certain flow path lengths that were traced along the river and slope above the sampling point. Coefficients of determination for dissolved (137)Cs concentrations were highest for the longest flow path, i.e., the whole catchment area, and lower for shorter flow paths. Coefficients of determination for particulate (137)Cs concentrations were only moderately high for the shortest flow path in 2012, whereas the values were quite low for all flow paths in 2013. These results suggest that dissolved (137)Cs can originate from a larger area of the catchment even under base-flow conditions; however, particulate (137)Cs did not show such behavior. The results also show that under base-flow conditions, dissolved and particulate (137)Cs behave independently during their transport from river catchments to the ocean.

Inventories of 239+240Pu, 137Cs, and excess 210Pb in sediments from freshwater and brackish lakes in Rokkasho, Japan, adjacent to a spent nuclear fuel reprocessing plant

We investigated the vertical profiles of (239+240)Pu, (137)Cs, and excess (210)Pb ((210)Pb(ex)) in sediment core samples obtained from two freshwater lakes and two brackish lakes situated near the first commercial spent nuclear fuel reprocessing plant in Rokkasho, Japan, before the final test of the plant using actual spent nuclear fuel. The inventory of (239+240)Pu in those lakes was larger than that in soil in Rokkasho, which indicated the inflow of (239+240)Pu from the catchment area in addition to direct deposition on the lake surfaces. The (137)Cs inventory in sediments of the brackish lakes was lower than that in the soil, which showed that part of the (137)Cs was removed from the sediments by the brackish water or that it was not deposited into the sediments, because of the high solubility of Cs in brackish water. The (137)Cs inventory in sediments of the freshwater lakes was higher than that of the brackish lakes, and comparable with that in soil except for one core sample out of four. The (239+240)Pu/(137)Cs ratio in freshwater lake sediments was higher than that in soil, and that indicated that part of the (137)Cs was lost from the sediments. The low inventory of (137)Cs may be attributable to competition for absorption sites in sediments with ammonium ions formed in the reducing environment which occurs from summer to fall in the sediments. Those data will be used as background data on the artificial radionuclides in the lakes to assess the effect of released radionuclides on their concentrations.

Transfer of 137Cs and stable Cs in soil-grass-milk pathway in Aomori, Japan

The soil-to-grass transfer factors and grass-to-milk transfer coefficients were determined for 137Cs and stable Cs in soil, grass and milk samples collected in Aomori Prefecture, Japan. The concentrations of 137Cs in the soil and grass samples collected from 25 sampling sites were 13±12 Bq.kg-1 and 2.0±2.1 Bq.kg-1 dry wt., respectively. The geometric mean of soil-to-grass transfer factor of 137Cs was 0.13 and its 95% confidence interval was 0.017-0.98. The transfer factor of 137Cs was higher than that of stable Cs, and they had a positive correlation. The concentration of K in the soil affected both transfer factors. The concentration of 137Cs in milk samples collected from 16 sites was 76±43 mBq.kg-1 fresh wt. and had a good correlation with that of stable Cs. The geometric mean of grass-to-milk transfer coefficient of 137Cs was 0.0027, assuming that a cows total daily intake was 20 kg of dry grass. The transfer coefficient of 137Cs was positively correlated with that of stable Cs.

New spectrometric technique for the determination of the isotopic ratio of 240Pu239Pu

A new technique for the determination of the isotopic ratio of 240Pu239Pu 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 240Pu239Pu for two environmental samples was estimated by this method.