Iodine fallout

Iodine fallout > grass > cows > milk > human consumption This is a very efficient concentration pathway. 

Half-lives span a very wide range (Table 17.5). Consider strontium-90, for which the half-life is 28 a. This nuclide is present in nuclear fallout, the fine dust that settles from clouds of airborne particles after the explosion of a nuclear bomb, and may also be present in the accidental release of radioactive materials into the air. Because it is chemically very similar to calcium, strontium may accompany that element through the environment and become incorporated into bones once there, it continues to emit radiation for many years. About 10 half-lives (for strontium-90, 280 a) must pass before the activity of a sample has fallen to 1/1000 of its initial value. Iodine-131, which was released in the accidental fire at the Chernobyl nuclear power plant, has a half-life of only 8.05 d, but it accumulates in the thyroid gland. Several cases of thyroid cancer have been linked to iodine-131 exposure from the accident. Plutonium-239 has a half-life of 24 ka (24000 years). Consequently, very long term storage facilities are required for plutonium waste, and land contaminated with plutonium cannot be inhabited again for thousands of years without expensive remediation efforts. 

Irwin Goodwin. Fallout of Atmospheric Nuclear Tests in 1950s and 1960s Exposed More People to Iodine-131 than Chernobyl Accident. Physics Today. 50 (Sept. 1997) 54-55. 

Values a and b for the fission product isotopes and the partition factors ai and a2 are listed in Table V au for a given isotope, is the fraction which was retained by the local fallout glass particles, and < > is the fraction released to the cloud. Thus, from Table V, i137 is 0.153 which indicates that 15.3% of the 137Cs is retained by the local glass particles. It is interesting to note that the independent yield of cesium in the 137 mass chain is approximately 17%—the balance of the chain is formed as tellurium, iodine, and xenon. 

It is apparent, then, that to understand the physical and chemical processes which govern the distribution of a particular long lived species —e.g., 140Ba—in a fallout field, one must consider the properties not of barium, or not only of barium, but of cesium, xenon, and perhaps even iodine, and tellurium (in fact in this case the relevant species appear to be barium, cesium, and xenon). 

Iodine should be given to the general population if the risk of radioiodine exposure is sufficient (over 15-100 rem), but people with increased susceptibility to the adverse effects of iodine (previous thyroid disease or known serious allergies) should be excluded (11-16). In elderly people the benefit of stable iodine probably does not outweigh its potential adverse effects, while in pregnant women and infants the benefit to harm balance is not established rapid evacuation of such people from fallout zones should be given the highest priority (SEDA-11, 358). 

Helsing E, Dukes MNG. The Safety of Stable Iodine When Used to Provide Protection against Nuclear Fallout. Internal Advisory ReportCopenhagen WHO Regional Office for Europe . 1986. 

One milliroentgen is 84 jj.Gy, and 1 /uCi is 3.7 x 104 Bq, so the above relation is equivalent to 227 pGy h-1 per Bq m-2, close to the result of Fig. 3.8, curve A. As Knapp emphasised, the relation assumed that there was no chemical fractionation of fission products. If there was fractionation, this might give a higher proportion of volatile fission products, such as iodine, in the long-range fallout (Section 2.3). 

Knapp, H.A. (1964) Iodine-131 in fresh milk and human thyroids following a single deposition of nuclear test fallout. Nature, 202, 534-7. 

Public interest in radioactive aerosols began in the mid-1950s, when world-wide fallout of fission products from bomb tests was first observed. The H-bomb test at Bikini Atoll in 1954 had tragic consequences for the Japanese fisherman, and the inhabitants of the Ronge-lap Atoll, who were in the path of the fallout. In 1957, radio-iodine and other fission products, released in the accident to the Windscale reactor, were tracked over much of Europe, and these events were repeated on a much larger scale after the Chernobyl accident. 

Epidemiological studies of populations in the FSU exposed to fallout from the 1986 nuclear reactor explosion at Chernobyl and releases from the Chelyabinsk-65 complex demonstrate the health effects associated with exposure to radioactive iodine, strontium, and caesium. A study of 2.81 X 10" individuals exposed along the Techa River, downstream from Chelyabinsk-65, revealed that a statistically significant increase in leukemia mortality arose between 5 yr and 20 yr after the initial exposure (37 observed deaths versus 14-23 expected deaths see Cochran et al. (1993) and cited references and comments). There has been a significant increase of thyroid cancers among children in the areas contaminated by fallout from the Chernobyl explosion (Harley, 2001 UNSCEAR, 2000). The initial external exposures from Chernobyl were due to and short-lived isotopes. Subsequently, external exposures to Cs and nd internal... 

The short-lived radioactive components in fallout from an atmospheric nuclear explosion, comprising mainly particulate fission products, can contribute significantly to radiation exposures in humans either by external irradiation due to material deposited on the ground or by uptake of radioactive iodine from food, especially milk. 

Increased radioactive fallout was first observed by the control system of a nuclear power plant on the east coast of Sweden after the Chernobyl accident. Nonetheless, no increase has later been observed in thyroid cancer incidence among children in that special region, emphasizing the importance of iodine sufficiency. 

Problem 10.56. One of the products of radiation fallout from atmospheric bomb testing or nuclear accidents as at Chernobyl is iodine-131. People living in a region where iodine-131 was known to have been deposited were encouraged to use salt enriched with nonradioactive iodine-127. What was the basis of this treatment ... 

Radioactive iodine gained notoriety through the nuclear disaster at the Chernobyl power plant in 1986, which resulted in an increase of thyroid carcinomas among small children by a factor of around 10-30. It is now presumed that many of these cancer cases might have been prevented by prophylactic administration of iodide. The longer term consequences of the nuclear fallout from the Fukushima Daiichi accident in 2011, where also a number of different radionuclides were released, are still being evaluated. 

Nuclear weapons present hazards in virtually all areas of their life cycle. Production and testing have their own impacts. The U.S. National Cancer Institute estimated that the release of iodine-131 in fallout from U.S. nuclear test explosions was by itself responsible for 49,000 excess cases of thyroid cancer among the U.S. popnlation [8]. A 1991 pubhcation by the hitemational Physicians for the Prevention of Nnclear War estimated that the strontium-90, cesium-137, carbon-14, and poloninm-239 released worldwide in all nuclear test explosions would be responsible for 430,000 cancer deaths by 2000 [9]. Additional widespread health and enviromnental effects of nuclear-weapons prodnction include massive contamination of land by radioactive materials and toxic chemicals. 

Mobile radioisotopes are available to immediately interact with soil compo-" nents while the others will reside in discrete fallout particles until they are released by weathering processes. There is an immense body of literatures dedicated to studying the uptake of mobile fallout Cs by clays (i.e., Poinssot et al., 1999) and the persistent but capricious retention of small amounts of fallout iodine in soils (Bors et al., 1988). 

Because of insufficient experimental data, many Of the physical and biologic characteristics of must be based on observations of other iodine isotopes. For example, studies of short-term iodine behavior have utilized fallout radioiodine from nuclear explosions, principally in particulate form, and releases of elemental vapor forms of in field experiments or associated with nuclear power generation. However, little information is available concerning the changes in bioenvironmental concentration processes that might result from alterations in form and availability of in the long term. Analyses of behavior and potential accumulation of released to the environment must therefore be based on studies of 1 as a model for shortterm behavior, and stable iodine for long-term behavior. 

KeisCH, B., Koch, R.C. and Edwards, R.R. (1963). Physical and Chemical States of Iodine in Fallout, Report No. NSEC-102 (Nuclear Science and Engineering Corporation, Pittsburgh, Pennsylvania). 

The Soviet tests revived apprehension about the effects of fallout that had subsided after the summer of 1959. The immediate source of concern was iodine 131. Although scientists had recognized as early as 1954 that radioiodine from atomic fission presented potential hazards, they had given much greater attention to strontium 90. In 1957 the Public Health Service had established five monitoring stations that detected iodine 131 in milk samples. 

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