Radiation: from atomic bombs

Child Leukaemia in children due to radiation from atomic bomb (IARC, 2000) Exacerbation of preexisting asthma from exposure to particulates in the air (Parnia et al., 2002) Ionizing radiation and leukaemia in childhood and adulthood (Chowet al., 1996 Ron et al., 1988a)... 

Figure 3 illustrates rough dose-response model fits with human data for ionizing radiation and leukemia incidence from atomic bomb survivors (24). Data exist down to about the 10-5 lifetime risk per person exposed. This value is close to the region of regulatory interest, and relatively small risk differences are predicted by the three illustrated models in the dose range up to two orders of magnitude below the last observed dose value (ca. 5 rad). 

Figure 3. Rough dose-response model fits with human data for ionizing radiation and leukemia incidence from atomic bomb...

The survivors from atomic bombs dropped in August 1945 were analyzed. Within 1 km of the epicenter 64,000 people were killed by the blast. From 1-2 km of the epicenter, people received doses as high as several Sv. At more than 2.5 km, irradiation was not significantly above background. Risk estimates are important because they are used for occupational exposure guidelines. The latest updates report that 5% of the solid cancer deaths and 0.8% of the noncancer deaths were estimated to be due to radiation exposure (>9,000 cancer deaths >31,000 noncancer deaths 47 years of follow-up). 

Life-span study (LSS). The ongoing study of the Japanese atomic bomb survivors at abcc/rerf. The base sample of the study consisted of 120,000 people, of whom 82,000 were exposed to radiation from the bombs, mostly low doses. Subsets of the life-span studies are still being utilized for abcc/rerf investigations. 

Most of the data on radiation health effects have come from medical monitoring of Japanese atomic bomb survivors. For survivors who received radiation exposures up to 0.10 Sv, the iacidence of cancer is no greater than ia the geaeral populatioa of Japanese citizens. For the approximately 1000 survivors who received the highest radiation doses, ie, >2 Sv, there have been 162 cases of cancer. About 70 cases would have been expected ia that populatioa from aatural causes. Of the approximately 76,000 survivors, as of 1995 there have beea a total of about 6,000 cases of cancer, only about 340 more cases than would be expected ia a group of 76,000 Japanese citizens who received only background radiation exposure (59). 

Mysteries such as this attract young people to science. Nuclear physics, however, tends to turn people off Nuclear power plant malfunctions and atomic bombs are frightening. Nevertheless, humankind has greatly benefited from scientific investigations of the nucleus. Science s hard-won knowledge of the atomic nucleus is used extensively in medicine, from imaging procedures such as positron emission tomography (PET) to radiation therapy, which has saved the lives of many cancer patients. 

Reference materials for radioisotopes have mainly been used for purposes relating to nuclear and radiation safety. Historically, the development of such materials first arose from the need to assess the risk to human populations caused by worldwide contamination of food and the environment as a consequence of atomic bomb testing - particularly from bombs exploded in the atmosphere. Even now, although atmospheric testing ceased many years ago, the residues from these tests still remain the main source of radionuclides such as Cs and °Sr in the global environment (though locally, other sources may be more important in some countries). 

Yamamoto M, Komura K, Sakanoue M, et al. 1985. Pu isotopes,241 Am and 137Cs in soils from the atomic bombed areas in Nagasaki and Hiroshima. J Radiat Res 26 211-223. 

Radiation is carcinogenic. The frequency of death from cancer of the thyroid, breast, lung, esophagus, stomach, and bladder was higher in Japanese survivors of the atomic bomb than in nonexposed individuals, and carcinogenesis seems to be the primary latent effect of ionizing radiation. The minimal latent period of most cancers was <15 years and depended on an individual s age at exposure and site of cancer. The relation of radiation-induced cancers to low doses and the shape of the dose-response curve (linear or nonlinear), the existence of a threshold, and the influence of dose rate and exposure period have to be determined (Hobbs and McClellan 1986). 

A significant body of data defines the relationship between radiation dose and cancer incidence. This dataset is primarily from a study of the atomic bomb survivors from Nagasaki and Hiroshima, Japan but also includes data from animal studies and other sources of information. While additional data are continuously collected and... 

The current health risks associated with exposure to low-dose radiation are extrapolated from high-dose data taken from the Life Span Study of the Japanese atomic bomb survivors. Currently, a linear no threshold extrapolation is recommended. The numerous technical reports and scientific papers about the Japanese A-bomb survivors were widely interpreted as showing that the effects of occupational exposures to radiation would be too small to detect in epidemiological studies. However, questions about the reliability of the A-bomb results were presented by Stewart and Kneale [2]. Their Oxford Childhood Study observed that children whose in utero exposures were as little as 10 to 20 mSv had 40% more childhood leukemias than those who were not exposed. No similar effects are reported in the A-bomb data. Of course, the finding of no effect is not a compelling argument for or against a safe dose. 

Gamma Radiation. The combined process of emission, transmission and absorption of gamma rays, as from, the expln of atomic bomb Ref Glossary of Ordn (1959), 133 L... 

These elements include potassium (found in food) and uranium, thorium, and radon (found in the soil and air). Estimates of cancer incidence from naturally occurring radioisotopes use data on human exposure to the atomic bombs dropped on Japan and to early radiation therapy. 

Blot, W.J., Akiba, S. and Kato, H. (1984). Ionizing radiation and lung cancer A review including preliminary results from a case-control study among A-bomb survivors, in Atomic Bomb Survivor Data Utilization and Analysis, PRENTICE, R.L. and Thompson, D.J., Eds. (SIAM, Philadelphia). 

In general, the adverse effects of radium are believed to be the consequence of the radiation emitted from the element itself and its daughter products. Because there is already a considerable amount of information on the effects of radiation on humans and animals derived from studies on the effects of the atomic bomb and of therapeutic x-ray and gamma-ray treatments of malignancies, the experimental animal studies with radium have made no attempt to duplicate this information. They have instead concentrated on radium s most sensitive endpoint, cancer. For example, it can be predicted that the beta and gamma rays emitted by a radium source will produce local radiation burns and tissue damage when the source is placed on human or animal skin, hence there have been no valid reasons to conduct such studies with radium. 

The second atomic bomb was dropped on Nagasaki on August 9, 1945. In this occasion, the number of dead was not so high as in Hiroshima because the people in Nagasaki had been warned previously. However, diseases and deaths from nuclear radiation have continued ever since August 15, 1945. 

The nominal probability coefficient for radionuclides normally used in radiation protection is derived mainly from maximum likelihood estimates (MLEs) of observed responses in the Japanese atomic-bomb survivors. A linear or linear-quadratic dose-response model, which is linear at low doses, is used universally to extrapolate the observed responses at high doses and dose rates to the low doses of concern in radiation protection. The probability coefficient at low doses also includes a small adjustment that takes into account an assumed decrease in the response per unit dose at low doses and dose rates compared with the observed responses at high doses and dose rates. 

The Japanese atomic-bomb survivors also are a potentially important source of data on the dose-response relationship for severe hereditary responses. However, no evidence for inherited genetic effects has been observed in spite of nearly 50 y of study. In the absence of data in humans, estimates of the frequency of radiation-induced hereditary responses have been based primarily on data from studies in mice. 

However, this option presents some difficulties for radionuclides, because studies of radiation effects in human populations have focused on cancer fatalities as the measure of response and probability coefficients for radiation-induced cancer incidence have not yet been developed by ICRP or NCRP for use in radiation protection. Probabilities of cancer incidence in the Japanese atomic-bomb survivors have been obtained in recent studies (see Section 3.2.3.2), but probability coefficients for cancer incidence appropriate for use in radiation protection would need to take into account available data on cancer incidence rates from all causes in human populations of concern, which may not be as reliable as data on cancer fatalities. Thus, in effect, if incidence were used as the measure of stochastic response for radionuclides, the most technically defensible database on radiation effects in human populations available at the present time (the data on fatalities in the Japanese atomic-bomb survivors) would be given less weight in classifying waste. 

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