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
岡島 俊三
出版者
日本放射線影響学会
雑誌
Journal of Radiation Research (ISSN:04493060)
巻号頁・発行日
vol.16, pp.35-41, 1975
被引用文献数
9

Fallout from the Nagasaki atomic bomb was mainly concentrated in the Nishiyama district of Nagasaki. Studies conducted in 1945 and 1946 indicated the average dose due to the external irradiation from fallout in Nishiyama to be as high as 30 to 130 R. A significant leucocytosis occurred among Nishiyama residents two months following the explosion. In the present 1969-1972 investigation, Nishiyama residents and appropriate comparison residents elsewhere in Nagasaki underwent comprehensive clinical evaluations including thyroid function and chromosome studies, radiochemical urinalysis and whole body counting. No clinical abnormalities were found among the Nishiyama residents, but whole body counting demonstrated significantly elevated <SUP>137</SUP>Cs concentrations with parallel results by radiochemical urinalysis. Increased <SUP>137</SUP>Cs contents of soil and agricultural products of the Nishiyama area were apparently responsible for the relatively high body burdens. The annual internal doses from <SUP>137</SUP>Cs in the Nishiyama district were estimated to be 0.292 mrad per year for males and 0.187 mrad for females.
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
山県 登 小平 潔 速水 泱
出版者
日本放射線影響学会
雑誌
Journal of Radiation Research (ISSN:04493060)
巻号頁・発行日
vol.3, no.3, pp.182-192, 1962-09
被引用文献数
2

Measurements have been made of the cesium-137 content in human musle, total diet and cereals collected in Japan during the period from February 1960 to May 1962. The simple methods of evaluation of mean levels in the human body are proposed which are based on the distribution studies on the common cesium irrespectively of potassium concentration or the cesium unit. The total body burden was estimated as 3. 2-4. 0 mμc for the period from August 1960 to January 1962 and it rose up to 7. 6 mμc in March 1962 in correspondence with the increased fallout deposition rate in Autumn 1961. The daily intake of cesium-137 by Japanese people was 29 μμc, on average, for the period from August 1960 to August 1961 and increased to 50 μμc in February 1962. The contribution of cesium-137 by cereals to the total intake was estimated as approximately 40% for the period from November 1960 to November 1961 and it decreased to 32% in February 1962. The relative decrease was attributed to the increase in the daily intake, probably other than cereal, through leafy vegetables.
著者
Minli WANG Megumi HADA Janice HUFF Janice M. PLUTH Jennifer ANDERSON Peter O'NEILL Francis A. CUCINOTTA
出版者
Journal of Radiation Research Editorial Committee
雑誌
Journal of Radiation Research (ISSN:04493060)
巻号頁・発行日
vol.53, no.1, pp.51-57, 2012 (Released:2012-02-02)
参考文献数
27
被引用文献数
13

TGFβ is a key modulator of the Epithelial–Mesenchymal Transition (EMT), a process important in cancer progression and metastasis, which leads to the suppression of epithelial genes and expression of mesenchymal proteins. Ionizing radiation was found to specifically induce expression of the TGF-β1 isoform, which can modulate late post-radiation changes and increase the risk of tumor development and metastasis. Interactions between TGFβ induced EMT and DNA damage responses have not been fully elucidated, particularly at low doses and following different radiation quality exposures. Further characterization of the relationship between radiation quality, EMT and cancer development is warranted. We investigated whether space radiation induced TGFβ dependent EMT, using hTERT immortalized human esophageal epithelial cells (EPC2-hTERT) and non-transformed mink lung epithelial cells (Mv1Lu). We have observed morphologic and molecular alterations in EPC2 and Mv1Lu cells consistent with EMT after pre-treatment with TGFβ1. This effect could be efficiently inhibited in both cell lines by the use of a TGFβRI inhibitor. High-energy silicon or iron nuclei were each able to cause a mild induction of EMT, with the inclusion of TGFβ1 inducing a greatly enhanced EMT phenotype even when cells were irradiated with doses as low as 0.1 Gy. A further enhancement of EMT was achieved at a higher dose of 2 Gy. TGFβRI inhibitor was able to reverse the EMT induced by the combination of TGFβ1 and radiation. These studies indicate that heavy ions, even at a low dose, may trigger the process of TGFβ1–induced EMT, and suggest further studies are needed to determine whether the chronic exposures received in space may potentiate this process in astronauts, leading to an increased risk of cancer.
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
Kazunori ANZAI Nobuo IKOTA Megumi UENO Minako NYUI Tsutomu V. KAGIYA
出版者
Journal of Radiation Research Editorial Committee
雑誌
Journal of Radiation Research (ISSN:04493060)
巻号頁・発行日
vol.49, no.4, pp.425-430, 2008 (Released:2008-07-17)
参考文献数
17
被引用文献数
12

In vivo radioprotection of C3H mice by i.p. administration of Zn-, Mn-, Cu-, or Se-containing heat-treated Saccharomyces serevisiae yeast sample was examined. The 30-day survival of the group treated 30 min before 7.5 Gy whole-body X-irradiation with mineral-containing yeast powders suspended in 0.5% methylcellulose was significantly higher than that of control group. When mineral-yeast was administered immediately after irradiation, the survival rate was even higher and Zn- or Cu-yeast showed the highest rate (more than 90%). Although treatment with simple yeast showed a high survival rate (73%), it was significantly lower than that obtained by the Zn-yeast treatment. The effects of Zn-yeast were studied further. When the interval between irradiation and administration was varied, the protective activity of Zn-yeast decreased gradually by increasing the interval but was still significantly high for the administration at 10 h post-irradiation. The dose reduction factor of Zn-yeast (100 mg/kg, i.p. administration immediately after irradiation) was about 1.2. When the suspension of Zn-yeast was fractionated by centrifugation, the insoluble fraction showed a potent effect, while the soluble fraction had only a moderate effect. In conclusion, mineral-yeast, especially Zn-yeast, provides remarkable post-irradiation protection against lethal whole body X-irradiation. The activity is mainly attributable to the insoluble fraction, whereas some soluble components might contribute to the additional protective activity.
著者
MARIA KOWALSKA
出版者
Journal of Radiation Research Editorial Committee
雑誌
Journal of Radiation Research (ISSN:04493060)
巻号頁・発行日
vol.26, no.4, pp.385-394, 1985-12-15 (Released:2006-06-16)
参考文献数
15

Three generations of rats were long-term exposed to HTO in drinking water at activity of 37.0 kBq/ml or to food containing OBT at activity of 48.1 kBq/g. The rats consumed tritiated water and tritiated food ad libitum. In the experiment the F1 and F2 generation of rats were exposed continuously from conception to the 21-st or 120-th day of age and rats of F3 generation during 22 days of their intrauterine life. It was found that the amount of tritium incorporated into the major rat brain phospholipids and gangliosides after administration of tritiated food was higher than after administration of tritiated water. Tritium activity in all studied phospholipids and gangliosides was the highest in 21-day-old rats exposed during both-pregnancy and lactation.
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
宮越 順二 OHTSU SHUJI TATSUMI-MIYAJIMA JUNKO TAKEBE HIRAKU
出版者
日本放射線影響学会
雑誌
Journal of Radiation Research (ISSN:04493060)
巻号頁・発行日
vol.35, no.1, pp.26-34, 1994-03
被引用文献数
20 24

To examine the biological effects of extremely low frequency magnetic field (ELFMF), we have designed and manufactured a new equipment for long-term and high-density exposure of cells to ELFMF. The ELFMF exposure system consists of a generator of magnets with a bult-in CO_2 incubator, an alternating current (AC) power supply, a gas compressor and a thermocontroller for the incubator, and a cooling unit for the magnets. The CO_2 incubator made of acrylic resin is inserted into the inner-space of the silicon steel strip-cores. In this system, the temperature of the incubator is maintained at 37±0.5°C. The maximum magnetic flux density on the exposure area of the incubator is 500 mT (T; tesla) at a current of 556 Arms (rms; root mean square) at 50 Hz. The long-term (up to 120 hr) exposure of 400 mT ELFMF did not affect the growth of both HL6ORG and CCRF-CEM cells originated from human leukemia.
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.

2 0 0 0 OA A. Acute Effects

著者
大北 威
出版者
Journal of Radiation Research Editorial Committee
雑誌
Journal of Radiation Research (ISSN:04493060)
巻号頁・発行日
vol.16, no.SUPPLEMENT, pp.49-66, 1975-09-16 (Released:2006-07-14)
参考文献数
132
被引用文献数
26

An outline of the acute effects of the Hiroshima and Nagasaki atomic bombs are summarized, based on documentary records. Acute injuries caused by the atomic bombs have been classified as thermal, mechanical, and radiation injuries. Combinations of these were most common. Many died from the immediate effects of blast and burns, but individuals often succumbed to trauma or burns before the radiation syndrome developed. Many more would have died from irradiation, had they been saved from the effects of trauma or burns. Nearly all who died within 10 weeks had signs suggestive of radiation injuries. Remarkable variation in sensitivity of body tissues to ionizing radiation was apparent. Radiation-induced bone marrow depletion was the most critical damage leading to death. In these instances, leukopenia and thrombocytopenia, and subsequent infections and hemorrhagic tendencies were the main causes of death. The clinical symptoms and signs of radiation injuries; the RBE of the atomic bomb neutrons for acute effects; and the effects of irradiation on spermatogenesis are also discussed.