Toxicity radioactive isotopes

Two forms of gold provide medical treatments. The radioactive isotope Au-198, with a short half-life of 2.7 days, is used to treat cancer and is produced by subjecting pure gold to neutrons within a nuclear reactor. A gold salt, a solution called sodium thiosulfate (AuNa O Cl ), is injected as an internal treatment for rheumatoid arthritis. However, since gold and some of its compounds are toxic when ingested, this treatment may cause complications such as skin rashes and kidney failure. It is a less popular treatment, particularly with the development of newer and more effective medications. 

III.b.1.6. Radioactive iodine. Radioactive iodine (Iodine-131) is a radioactive isotope of iodine, usually taken in an oral solution formulation as sodium 1. Given orally as sodium I, radioactive iodine is rapidly absorbed, concentrated and stored in the thyroid follicles. The therapeutic effect depends on beta-ray emission and destruction of thyroid parenchyma manifests some weeks after treatment. It is relatively safe, cheap, painless and avoids side effects associated with surgery. It is widely regarded as the treatment of choice in adults with toxic multinodular goiter, toxic nodule and people who relapse after a course of antithyroid medication. 

The radioactive isotopes of most concern in high level waste (HLW) and their estimated toxicities after several decay periods are given in Table I. These data are largely taken from Wallace ( 1) supplemental estimates from calculations based on ORIGEN code information(2) are included. Other isotopes of the transuranic elements 2U5,2it6,2U7cm),... 

Table I. Radioactive Isotopes in Stored High Level Wastes Having Half-Lives Greater than One Year and Their Estimated Relative Toxicities (Revision of Wallace Data)...

Worldwide, the amount of energy available from coal is estimated to be about ten times greater than the amount available from all petroleum and natural gas reserves combined. Coal is also the filthiest fossil fuel because it contains large amounts of such impurities as sulfur, toxic heavy metals, and radioactive isotopes. Burning coal is therefore one of the quickest ways to introduce a variety of pollutants into the air. More than half of the sulfur dioxide and about 30 percent of the nitrogen oxides released into the atmosphere by humans come from the combustion of coal. As with other fossil fuels, the combustion of coal also produces large amounts of carbon dioxide. 

Is an ingredient, inpurity, degradation product, metabolite, or radioactive isotope of a substance described by paragraph (1) of this definition, or some other substance related to a substance described by that paragraph, which is used in the study to assist in characterizing the toxicity, metabolism, or other characteristics of a substance described by that paragraph. 

A typical nuclear industry may consist of mining and milling of uranium ore, thorium extraction, fuel fabrication, nuclear reactor operation, and production and application of radioactive isotopes for various industrial medical and research purposes. Almost, in all these steps, waste is generated that needs proper management. Radioactive wastes differ from other industrial wastes due to its radiation exposure and its radiological toxicity to human beings and their environment. Management of radioactive wastes is an important step in a nuclear industry and the objective is to effectively isolate radionuclides from the... 

One radioactive isotope of strontium, strontium-90, is of special interest. It is a toxic substance, which, at one time, was the cause of great concern because of its connection to atomic bomb testing. 

Its inherent toxicity and that of its compounds resembles that of calcium. The state of calcium nutrition of exposed individuals is a major determinant of toxicity. The radioactive isotope, when ingested or inhaled, is processed by the body and resides in bones. Strontium ionizes molecules in the body by the emission of beta particles. It increases the risk of cancer. 

Fission reactors produce of kilograms quantities of highly radioactive cesium 137, iodine 131, and strontium 90. Tons of uranium and plutonium are also present in a fission reactor. If released in an accident these radioactive isotopes can be absorbed by the body and retained for some length of time. The fusion reactions do not use or produce any of these toxic elements. 

Many people, including environmentalists, regard nuclear fission as a highly undesirable method of energy production. Many fission products such as strontium-90 are dangerous radioactive isotopes with long half-lives. Plutonium-239, used as a nuclear fuel and produced in breeder reactors, is one of the most toxic substances known. It is an alpha emitter with a half-hfe of 24,400 yr. 

The trace alkali and alkaline earth cations are present in the following amounts lithium, 10-300 mg kg-1 rubidium, 20-500 mg kg-1 beryllium, 0.5-10 mg kg-1 strontium, 600-1000 mg kg-1 barium, 100-3000 mg kg-1 and radium, perhaps 10-7 mg kg-1. Some varieties of fmit trees are sensitive to as little as l mg L-1 Li+ in irrigation water, but Li+ toxicity is rare. Rubidium, cesium, strontium, and barium have all been studied in the laboratory, but have received little attention in the field. Strontium has been studied because its radioactive isotope 90Sr (half-life = 28 years) is produced by nuclear fission and could cause long-term soil contamination after nuclear explosions or accidents. In soils the toxic Be2+ ion behaves more like AI3 1 than like the other alkaline earth cations. 

Thorium is a ubiquitous element found in the upper layers of the Earth s crust. It exists only as unstable, radioactive isotopes, which undergo a long chain of radioactive decays to end up finally as stable isotopes of lead (Pfennig etal. 1995). Due to their comparatively short half-lives, these decay products are present in the environment in only minute quantities. Both the chemical toxicity of the long-lived thorium parent isotope and the radiotoxicity of all other thorium isotopes and unstable decay products may cause considerable hazards after enrichment, or even at environmental levels. 

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