著者

葉佐井 博巳 星 正治 横路 謙次郎

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.32, no.SUPPLEMENT, pp.32-39, 1991 (Released:2006-05-31)

参考文献数

12

被引用文献数

1 1 1

---

Three studies of fallout measurements were reviewed for the discussion of possible radioactivity intake from the Hiroshima atomic bomb. The first study discussed correlations between enriched 234U and 137Cs specific activities from the measurement of soil samples collected in the “black rain” area. The second study measured 137Cs activity on the rock and roof tile samples collected in the hypocenter area immediately after the explosion. Some of the rock and roof tile samples collected near the hypocenter had a small but detectable amount of 137Cs activity. However, it has been determined that 137Cs exposure, for example, was negligible compared with DS86 dose estimates, since these activity levels were low. The third study detected 90Sr activity in some of the specimens of human bones exhumed on Ninoshima Island. This study compared the difference in activity between the bone head and shaft, with higher activities obtained in the bone head. This fact suggests a short intake period for this activity, however, the levels of 90Sr contamination were too low to allow a discussion of the exposure risks.

著者

伊沢 正実 坪田 博行

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.3, no.2, pp.120-129, 1962

被引用文献数

5

---

To evaluate hazards of environmental contamination due to fission products from nuclear weapon test explosions, determination of body burden of the radionuclides taken in human body is essential. Because urine analysis is one of the practical methods to estimate body burden, Cs-137 concentration in human urine has been surveyed in Osaka and Ishikawa Prefectures since the fall of 1959. From the results of analyses, time variation of Cs-137 concentration and difference between two sampling sites were discussed with respect to the fallout rate. Cs-137 body burden was estimated from the analytical results by assuming the exponential equation for continuous exposure : In November 1959 the values were 8.4 mμc in Ishikawa and 6.0 mμc in Osaka respectively. And they decreased to 3 mμc in October 1961 in both areas. These values were consistent with the results obtained by other methods. Cs-137 gonad dose could be calculated with these values assuming uniform distribution of Cs-137 in a human body. Gonad dose rate due to internally deposited Cs-137 at present is about 0.7 mrad/y, and gonad dose up to the present is in the range of 5 to 8 mrad.

著者

Yuko HIRAI Yoshiaki KODAMA Harry M. CULLINGS Chuzo MIYAZAWA Nori NAKAMURA

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

pp.1107140221-1107140221, (Released:2011-07-16)

参考文献数

28

被引用文献数

8

---

The atomic bombs in Hiroshima and Nagasaki led to two different types of radiation exposure; one was direct and brief and the other was indirect and persistent. The latter (so-called exposure to residual radiation) resulted from the presence of neutron activation products in the soil, or from fission products present in the fallout. Compared with the doses from direct exposures, estimations of individual doses from residual radiation have been much more complicated, and estimates vary widely among researchers. The present report bases its conclusions on radiation doses recorded in tooth enamel from survivors in Hiroshima. Those survivors were present at distances of about 3 km or greater from the hypocenter at the time of the explosion, and have DS02 estimated doses (direct exposure doses) of less than 5 mGy (and are regarded as control subjects). Individual doses were estimated by measuring CO2– radicals in tooth enamel with the electron spin resonance (ESR; or electron paramagnetic resonance, EPR) method. The results from 56 molars donated by 49 survivors provided estimated doses which vary from –200 mGy to 500 mGy, and the median dose was 17 mGy (25% and 75% quartiles are –54 mGy and 137 mGy, respectively) for the buccal parts and 13 mGy (25% and 75% quartiles: –49 mGy and 87 mGy, respectively) for the lingual parts of the molars. Three molars had ESR-estimated doses of 300 to 400 mGy for both the buccal and lingual parts, which indicates possible exposures to excess doses of penetrating radiation, although the origin of such radiation remains to be determined. The results did not support claims that a large fraction of distally-exposed survivors received large doses (e.g. 1 Gy) of external penetrating radiation resulting from residual radiation.

著者

M. UCHIYAMA G. TANAKA S. AKIBA

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.23, no.3, pp.358-370, 1982-09-15 (Released:2006-06-16)

参考文献数

17

被引用文献数

1 4

---

A dose of 2.74 kBq of carrier-free 131I (NaI) was given orally to 2 male adults (A and B) in their routine works under a limitation of iodine intake for A and a fairly free access to iodine intake for B for 2 weeks predose. In both the thyroid and the whole-body, the retentions were expressed with a 2 term-exponential function. The metabolic data for subjects A and B are as follows: (1) a peak thyroidal uptake; 28.9 and 10.3% at 24 hours postdose (2) an effective half-time in the thyroid; 6.4 and 6.1 days (3) an effective half-time in the thighs; 0.2 and 0.3 day (4) excretion of 131I in the first 24-hr urine; 72 and 88% of the given dose (5) an amount of stable iodine in 24-hr urine before 131I administration; 0.29 and 2.0 to 5.4 mg. The dose commitments were estimated 1.19 and 0.39 mGy to the thyroid and 1 and 0.5 μGy to the total body for subjects A and B, respectively. The same results were obtained using the “S”, by MIRD.

著者

Shahla MOHAMMADI Mahnaz TAGHAVI-DEHAGHANI Mohammad R. GHARAATI Reza MASOOMI Mehdi GHIASSI-NEJAD

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.47, no.3+4, pp.279-285, 2006 (Released:2006-11-25)

参考文献数

56

被引用文献数

27

---

The hot springs in certain areas of Ramsar contain 226Ra and 222Rn. The effects of natural radiation on the inhabitants of these areas and the inhabitant's radiosensitivity or adaptive responses were studied. One group of volunteers from areas with high natural background radiation and another group from areas with normal background radiation were chosen as the case and control group respectively. The frequency of micronuclei, apoptosis, and DNA damage in peripheral blood mononuclear cells were measured following γ irradiation (4 Gy). The incidence of micronuclei in the case group was significantly lower than that in the control group while their frequency of apoptosis was higher (P < 0.05). However, the rates of induced DNA damage and repair were significantly higher in the case group (P < 0.05). Smaller number of micronuclei and higher levels of apoptosis in the case group could be the result of higher resistance to radiation stress and a more rigorous checkpoint at cell division. However, regarding the alkaline labile sites, the individuals in the case group are more sensitive and susceptible to DNA damage. The results of micronuclei, apoptosis and repair studies suggest that an adaptive response might be induced in people residing in areas with high background radiation.

著者

Shahla MOHAMMADI Mahnaz TAGHAVI-DEHAGHANI Mohammad R. GHARAATI Reza MASOOMI Mehdi GHIASSI-NEJAD

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

pp.0609140008-0609140008, (Released:2006-09-21)

参考文献数

56

被引用文献数

27

---

The hot springs in certain areas of Ramsar contain 226Ra and 222Rn. The effects of natural radiation on the inhabitants of these areas and the inhabitant's radiosensitivity or adaptive responses were studied. One group of volunteers from areas with high natural background radiation and another group from areas with normal background radiation were chosen as the case and control group respectively. The frequency of micronuclei, apoptosis, and DNA damage in peripheral blood mononuclear cells were measured following γ irradiation (4 Gy). The incidence of micronuclei in the case group was significantly lower than that in the control group while their frequency of apoptosis was higher (P < 0.05). However, the rates of induced DNA damage and repair were significantly higher in the case group (P < 0.05). Smaller number of micronuclei and higher levels of apoptosis in the case group could be the result of higher resistance to radiation stress and a more rigorous checkpoint at cell division. However, regarding the alkaline labile sites, the individuals in the case group are more sensitive and susceptible to DNA damage. The results of micronuclei, apoptosis and repair studies suggest that an adaptive response might be induced in people residing in areas with high background radiation.

著者

野口 邦和 清水 雅美 安斎 育郎

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.27, no.2, pp.191-212, 1986-06-15 (Released:2006-06-16)

参考文献数

9

被引用文献数

4 5

---

Correlation between natural background radiation exposure rates and cancer mortality rates in 46 Japanese prefectures was statistically studied over the period of 1950-1978. With regard to the correlation between natural background radiation exposure rates and crude (non-age-adjusted) cancer mortality rates, statistically significant positive correlation coefficients were observed in most cases of cancers with only a few exceptions. But the significance of correlation mostly disappeared through age-adjustment with only three exceptions of female stomach and uterine cancers in 1968-1978 and uterine cancer in 1958-1978. Both crude and age-adjusted male esophagus cancer mortality rates in 1968-1978 showed significant negative correlation. Female lung and breast cancers in 1958-1967, female esophagus and pancreas cancers in 1968-1978, and female breast cancer in 1958-1978 came to be negatively correlated with exposure rate through age-adjustment. It was suggested that natural radiation levels are positively correlated with prefectural population component ratios for those older than 40, 50 and 65 yrs, which was considered to be one of the causes of apparent correlation between exposure rates and crude cancer mortality rates.

著者

井上 義和 阪上 正信

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.11, no.2, pp.98-106, 1970-08-01 (Released:2006-08-29)

参考文献数

13

被引用文献数

5 6

---

The contents of plutonium-239 in soil were determined by using 238Pu as yield tracer. The samples were decomposed by nitric acid treatment under ultrasonic vibration and the separation of plutonium from other elements was carried out by using anion exchange resin. The surface soils showed the plutonium content of about 1 ?? 4 mCi/km2 and their 239Pu/90Sr activity ratios were 2 ?? 5%. From these results, it was concluded that 239Pu in soil at present was brought mainly by the fall-out due to the nuclear bomb test explosion.

著者

Suk Chul SHIN Yu Mi KANG Young Woo JIN Hee Sun KIM

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.50, no.3, pp.261-266, 2009 (Released:2009-06-16)

参考文献数

34

被引用文献数

18

---

This study evaluated the effects of low dose radiation on spermatogenic cells using the morphological characteristics of sperm in the caudal epididymis of ICR mice. In this study, six abnormal sperm shapes (amorphous heads, blunt hooks, excessive hooks, two heads and tails, folded tails and short tails) were observed at eight days after γ-irradiation (137Cs, 0, 0.2, 0.5, 1, 2 or 4 Gy) with both a high-dose-rate (0.8 Gy/min) and a low-dose-rate (0.7 mGy/hr). Fewer abnormal forms of sperm were observed in low-dose-rate irradiated mice than in mice that received a high-dose-rate irradiation (P = 0.002). The ratio of the dose rate effect among low-dose-rate irradiated mice to high-dose-rate irradiated mice was approximately 0.6. In addition, sperm with blunt hooks and two heads and tails significantly increased in number after irradiation, potentially providing an endpoint marker for estimating the effects of radiation. This study suggests that low-dose-rate (0.7 mGy/hr) radiation does not damage stem spermatogonia and probably stimulates repair in damaged spermatogonial stem cells in male mice.

著者

大竹 正徳 WILLIAM J. SCHULL HIROSHI YOSHIMARU

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.32, no.SUPPLEMENT, pp.249-264, 1991 (Released:2006-05-31)

参考文献数

33

被引用文献数

23 56

---

Significant effects on the developing brain of exposure to ionizing radiation are seen among those individuals exposed in the 8th through the 25th week after fertilization. These effects, particularly in the most sensitive period, 8-15 weeks after fertilization, manifest themselves as an increased frequency of severe mental retardation (SMR), a diminution in IQ score and in school performance, and an increase in the occurrence of seizures. Of 30 SMR cases, 18 (60%) had small heads. About 10% of the individuals with small head sizes observed among the in utero clinical sample were mentally retarded. When all of the cases of mental retardation are included in the analysis, a linear dose-response model fits the data adequately and no evidence of a threshold emerges; however, if the two probable nonradiation-related cases of Down''s syndrome are excluded from the 19 SMR cases exposed 8-15 weeks after fertilization, the evidence of a threshold is stronger. The 95% lower bound of the threshold based on the new dosimetry system appears to be in the range of 0.12-0.23 Gy. In the 16-25 week period, the 95% lower bound of the threshold is 0.21 Gy both with and without inclusion of two probable nonradiationrelated retarded cases. In a regression analysis of IQ scores and school performance data, a greater linearity is suggested with the new dosimetry (DS86) than with the old (T65DR), but the mean IQ score and the mean school performance of those exposed in utero to doses under 0.10 Gy are similar, and not statistically different from the means in the control group. The risk ratios for unprovoked seizures, following exposure during the 8th through the 15th week after fertilization, are 4.4 (90% confidence interval: 0.5-40.9) after 0.10-0.49 Gy and 24.9 (4.1-191.6) after 0.50 Gy or more when the mentally retarded are included and 4.4 (0.5-40.9) and 14.5 (0.4-199.6), respectively, when they are excluded.

著者

千葉 盛人 市川 龍資

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.9, no.1, pp.12-18, 1968-03-01 (Released:2006-08-29)

参考文献数

17

被引用文献数

3 4

---

In view of possible radioactive iodine accumulation by thyroid of breast-fed infant through maternal milk under a certain contaminated environment, the secretion rate of dietary iodine into human milk was estimated by iodine determination for diet and milk. For several hundred μg daily intake level, the secretion rate is around 10 per cent, whereas less than one per cent is found for 10 mg intake level.

著者

Iryna ABRAMENKO Nadiia BILOUS Anatolyi CHUMAK Alexey KOSTIN Zoya MARTINA Iryna DYAGIL

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.53, no.3, pp.497-503, 2012 (Released:2012-06-01)

参考文献数

53

被引用文献数

10 4

---

An association between DNA repair gene polymorphisms, environmental factors, and development of some types of cancer has been suggested by several studies. Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in the clean-up workers of the Chernobyl Nuclear Power Plant (NPP) accident and it has some specific features. Therefore, we have studied the possible differences in DNA repair gene polymorphisms in CLL patients depending on ionizing radiation (IR) exposure history and their clinical characterictics. Arg399Gln XRCC1, Thr241Met XRCC3, and Lys751Gln XPD polymorphisms were studied in 64 CLL patients, exposed to IR due to the Chernobyl NPP accident, 114 IR-non-exposed CLL patients, and 103 sex- and age-matched IR-exposed controls using polymerase chain reaction-restriction fragment-length polymorphism analysis. All investigated polymorphisms were equally distributed between two groups of CLL patients and IR-exposed controls, except that that there was a significant reduction of the common homozygous Lys/Lys XPD genotype among IR-exposed CLL patients (23.7%) compared with IR-exposed controls (45.6%), OR = 0.37; 95% CI = 0.18–0.75; (P = 0.005). The number of IR-non-exposed CLL patients (37.4%) with the Lys/Lys XPD genotype was also decreased compared to IR-exposed controls, although this difference was not significant (P = 0.223). These preliminary data suggest a possible modifying role of Lys751Gln XPD polymorphism for the development of CLL, expecially in radiation-exposed persons.

著者

Ashu Bhan TIKU Suresh K. ABRAHAM Raosaheb K KALE

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.45, no.3, pp.435-440, 2004 (Released:2004-12-22)

参考文献数

31

被引用文献数

37 33

---

In the present work, an attempt has been made to evaluate the possible in vivo radioprotection by eugenol. Swiss albino mice were administered different doses of eugenol (75,150 and 300 mg/kg) before exposure to 1.5 Gy of gamma radiation. The micronucleus test was carried out to determine the genetic damage in bone marrow. Our results demonstrated significant reduction in the frequencies of micronucleated polychromatic erythrocytes (MnPCEs) with all three eugenol doses. Eugenol (150 mg/kg) was also tested against different doses of radiation (0.5, 1, 1.5, and 2 Gy) and was found to afford significant radioprotection. Reduction in the incidence of MnPCEs could be noticed up to 72 h postirradiation (1.5 Gy). Moreover, the level of peroxidative damage and the specific activities of lactate dehydrogenase (LDH) and methylglyoxalase I (Gly I) were observed in the liver of mice treated with eugenol for seven days in comparison to untreated mice. The results revealed that eugenol exerted significant protection against oxidative stress. This possibility was further supported by the enhanced response of Gly I and the lowered activity of LDH. The present findings suggested that eugenol has a radioprotective potential.

著者

Hironobu IKEHATA Tetsuya ONO

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.52, no.2, pp.115-125, 2011 (Released:2011-03-19)

参考文献数

146

被引用文献数

384

---

Ultraviolet (UV) light induces specific mutations in the cellular and skin genome such as UV-signature and triplet mutations, the mechanism of which has been thought to involve translesion DNA synthesis (TLS) over UV-induced DNA base damage. Two models have been proposed: "error-free" bypass of deaminated cytosine-containing cyclobutane pyrimidine dimers (CPDs) by DNA polymerase η, and error-prone bypass of CPDs and other UV-induced photolesions by combinations of TLS and replicative DNA polymerases—the latter model has also been known as the two-step model, in which the cooperation of two (or more) DNA polymerases as misinserters and (mis)extenders is assumed. Daylight UV induces a characteristic UV-specific mutation, a UV-signature mutation occurring preferentially at methyl-CpG sites, which is also observed frequently after exposure to either UVB or UVA, but not to UVC. The wavelengths relevant to the mutation are so consistent with the composition of daylight UV that the mutation is called solar-UV signature, highlighting the importance of this type of mutation for creatures with the cytosine-methylated genome that are exposed to the sun in the natural environment. UVA has also been suggested to induce oxidative types of mutation, which would be caused by oxidative DNA damage produced through the oxidative stress after the irradiation. Indeed, UVA produces oxidative DNA damage not only in cells but also in skin, which, however, does not seem sufficient to induce mutations in the normal skin genome. In contrast, it has been demonstrated that UVA exclusively induces the solar-UV signature mutations in vivo through CPD formation.

著者

藤田 晃 松並 忠男 真室 哲雄

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.8, no.1, pp.32-36, 1967 (Released:2006-08-29)

参考文献数

9

被引用文献数

1 1 3

---

The measurement of the specific gravity of the highly radioactive fallout particles from the third Chinese nuclear test explosion was made. The specific gravity ranged from 5.2 to 6.5 and there was a tendency that the specific gravity increased with increasing darkness of the particle color. In connection with the results obtained by the electron microprobe analyses made previously, it was assumed that the specific gravity increased with increasing ratio of iron to aluminium in the matrix materials.

著者

Tohru OKADA Tadashi KAMADA Hiroshi TSUJI Jun-etsu MIZOE Masayuki BABA Shingo KATO Shigeru YAMADA Shinji SUGAHARA Shigeo YASUDA Naoyoshi YAMAMOTO Reiko IMAI Azusa HASEGAWA Hiroshi IMADA Hiroki KIYOHARA Kenichi JINGU Makoto SHINOTO Hirohiko TSUJII

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.51, no.4, pp.355-364, 2010 (Released:2010-07-29)

参考文献数

49

被引用文献数

130

---

In June 1994, the world's first clinical center offering carbon ion radiotherapy opened at the National Institute of Radiological Science (NIRS), Japan. Among several types of ion species, carbon ions were chosen for cancer therapy because they were judged to have the most optimal properties in terms of superior physical and biological characteristics. As of March 2010, 5,196 patients have been registered for carbon ion radiotherapy. Clinical results have shown that carbon ion radiotherapy has the potential to provide a sufficient radiation dose to the tumor, while having acceptable morbidity in the surrounding normal tissues. Tumors that appear to respond favorably to carbon ions include locally advanced tumors as well as histologically non-squamous cell tumor types such as adenocarcinoma, adenoid cystic carcinoma, malignant melanoma, hepatoma, and bone/soft tissue sarcoma. By taking advantage of the unique properties of carbon ions, treatment with small fractions within a short treatment period has been successfully carried out for a variety of tumors. This means that carbon ion radiotherapy can offer treatment for larger numbers of patients than is possible with other modalities over the same time period.

著者

Nobuo TAKEICHI Masaharu HOSHI Shozo IIDA Kimio TANAKA Yuka HARADA Zhaxybay ZHUMADILOV Nailya CHAIZHUNUSOVA Kazbek N. APSALIKOV Yoshihiro NOSO Toshiya INABA Kenichi TANAKA Satoru ENDO

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.47, no.SupplementA, pp.A171-A177, 2006 (Released:2006-03-28)

参考文献数

25

被引用文献数

9

---

Chromosomal studies in peripheral lymphocytes from 63 residents near the Semipalatinsk nuclear test site, at ages of 52-63 years old, were performed in 2001-2002. A higher rate of chromosome aberrations was observed in the two contaminated villages, Dolon and Sarjal, compared with the control village, Kokpekti. Moreover, a relationship of frequency of cells with radiation induced chromosome aberrations and the previously estimated exposure dose was observed. Furthermore, apparent nuclear abnormalities (ANA) of thyroid follicular cells were studied in 30 out of 63 residents, who were examined for chromosome aberrations. A higher rate of ANA was also found in the residents in the exposed villages compared with those in the control village. These results suggest radiation effects both on the chromosomes in peripheral lymphocytes and on the follicular cells in the thyroid.

著者

市丸 道人 石丸 寅之助 JOSEPH L. BELSKY

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.19, no.3, pp.262-282, 1978-09-15 (Released:2006-07-14)

参考文献数

38

被引用文献数

35 57

---

The leukemogenic effect of atomic radiation was examined in relation to age at the time of the bomb (ATB), calendar time, and type of leukemia over the period 1950-71. Confirmed cases of leukemia in the Leukemia Registry, a fixed cohort of 109, 000 subjects and the T65 dose calculations provided the basis for the analysis. Calendar time was divided into three periods, 5-10, 10-15, and 15-26 years after the bombs. The larger the exposure dose and the younger the age ATB, the greater was the effect in the early period and the more rapid was the decline in risk in subsequent years. In the oldest group, aged 45 or over ATB, the increase in risk appeared later and was sustained in the period 1960-71. Chronic granulocytic leukemia contributed substantially to the total leukemogenic effect initially but made little contribution after 1955. Sensitivity to the leukemogenic effect of atomic radiation not only depended on age ATB but its expression varied by type of leukemia and with time after exposure. Although the effect of atomic radiation on the incidence of leukemia in the atomic survivors is now greatly reduced and apparently on the wane, in the period 1966-71 the incidence was still greater than expected, especially in Hiroshima. In the Nagasaki sample, no case of leukemia was observed among the high-dose subjects from July 1966 to the end of 1971.

著者

中島 裕夫

出版者

Journal of Radiation Research 編集委員会

雑誌

日本放射線影響学会大会講演要旨集

巻号頁・発行日

vol.2011, pp.166, 2011

---

東日本大震災により発生した福島原発事故は広範囲の放射能汚染を引き起こした。この汚染状況については近々文科省・大学連携調査による詳細な汚染マップが作成されることになっているが、この汚染がどれくらい続くかの予測は非常に難しく実際には時間経を待たなければ正確にはわからないのが現状である。しかし、今後の除染作業や避難指定期間などを検討する上では重要な因子の1つと考えられることから、<SUP>137</SUP>Csの生体内動態を調べるとともに今までに報告されているデータを基に福島原発事故汚染地域に棲息する動物を中心とした当初の生態学的半減期の推測を試みた。<BR>【方法】<B>生体内動態</B>1.マウスに1kBq/g体重の<SUP>137</SUP>CsCl水を単回経口投与した群、10ならびに100Bq/mlの<SUP>137</SUP>CsCl水溶液を8ヶ月間自由摂取させた群において<SUP>137</SUP>Csの摂取条件(高濃度急性、低濃度慢性摂取)のちがいによる<SUP>137</SUP>Csの経時的体内動態の差異を調べた。2.植物葉の汚染状況の経時的変化を調べ、動物の摂取状態と摂取量の変化を予測した。<BR><B>生態学的半減期の推測</B> 今までに得られている1960年代の大気圏内核実験ならびに1986年のチェルノブイリ原発事故による日本への放射性降下物に由来する<SUP>137</SUP>Csホールボディーカウントの半減期(Uchiyama,M. et al.1996)、ノルウェー(Jonsson,B. et al. 1999)とイギリス(Smith,JT. Et al. 2000)の湖のマス体内の<SUP>137</SUP>Cs量の半減期、以前、本学会で報告した1997年から2005年におけるチェルノブイリ汚染地域動物体内の<SUP>137</SUP>Cs減少率(Nakajima,H. et al. 2006)などのデータを基にして、今後、新たに放射性物質の広範囲な放出がないという条件で福井原発汚染における当初の生態学的半減期(動物体内)の推測を試みた。<BR>【結果】生態系での初期では葉表面に付着した降下<SUP>137</SUP>Csを直接摂取する形で大量の<SUP>137</SUP>Csを体内へ取り込んだと考えられ、時間の経過と共に雨などで洗い流された<SUP>137</SUP>Csが土壌に浸透し、植物等の根からの吸引により植物体内へ移行したものを摂取していると考えられる。また、<SUP>137</SUP>Csの生態学的半減期(動物体内)は、おおよそ1.5年と推測された。

著者

高辻 俊宏

出版者

Journal of Radiation Research 編集委員会

雑誌

日本放射線影響学会大会講演要旨集

巻号頁・発行日

vol.2010, pp.41, 2010

---

長崎の黒い雨の科学的記録は限られている。その記録によれば、黒い雨は爆発後約20分後に爆心から約3km東にある西山地区で降り出した。爆発時は風速約3m/sの南西の風であったと報告されている。しかし、<SUP>239,240</SUP>Puと、<SUP>137</SUP>Csの有意な汚染は主として爆心から真東の地域に見つかっている。西山地区の<SUP>239,240</SUP>Pu濃度と外部線量率は、広島の黒い雨地域よりはるかに高かった。降雨は爆心近くの多くの地点で報告されている。少し遠いが、爆心から北西約19 km の大村海軍病院では、爆発後約10分で天気雨が報告されている。しかし、雨は黒くなかった。<BR> 黒い灰と微軽量物が爆心から真東の地域で降り、それは、爆心から10 kmにまで届いたと報告されている。畑は微軽量物で薄白くなり、サトイモの葉には指で字が書けたと報告されている。<BR> 原爆被爆者として公式認定されなかった人々は、西山地区を含む広い範囲に爆発直後、強い放射性降下物があったはずだと主張して、日本政府に認定を求める訴訟を起こした。西山地区における爆発1時間後からの人体への最大外部積算線量は、約0 .4 Gyと見積もられた。また、ホールボディカウンタによる測定や染色体の調査では、高線量内部被ばくの兆候はなかった。しかし、外部線量の直接測定は爆発後48日目から始められ、ホールボディカウンタによる測定と染色体の調査は1969年に始まった。当時の西山地区住民の多くは地区で育った野菜を食べ、西山水源池の水を飲んでいたものと思われる。西山水源地の水を毎日飲んでいた当時の一人の住人は、爆発1年後から、のどが腫れ、痛み出したと言っている。爆発後初期の内部被ばくの評価が重要である。