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iODINE 131/125

iODINE 131/125. By Pablo Barillas M ay 3 rd 2011 Dr. Mason. Structure of the Compound and Physical Properties. Both I-131 and I-125 are radioactive isotopes of naturally occurring I-127. I-131 is highly radioactive and gives of energy in both beta and gamma radiation.

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iODINE 131/125

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  1. iODINE131/125 By Pablo Barillas May 3rd 2011 Dr. Mason

  2. Structure of the Compound and Physical Properties • Both I-131 and I-125 are radioactive isotopes of naturally occurring I-127. • I-131 is highly radioactive and gives of energy in both beta and gamma radiation. • I-131 has a half-life of 8 days and decays into stable Xenon 131. • Created by nuclear fission of either uranium or plutonium.

  3. Structure of the Compound and Physical Properties continued • I-125 has electron capture radiation decay where a proton will capture an electron and give off a neutrino. • I-125 has a half-life of 59 days will decay into Tellurium 125. • I-125 is created by the electron capture decay of Xenon 125.

  4. Chemical Properties • Iodine as a molecule is nonpolar and is highly soluble in non polar organic solvents. • Due to its nonpolar nature, it does not dissolve well in water. • Solubility is aided by iodide ions already in the water, such as from HI, KI etc and will form the triiodide ion, I3− • Iodine is easily oxidized and easily reduced as well.

  5. History, Uses and Application • I-131 was discovered by Glenn T. Seaborg and John Livingood at the University of California Berkeley in the late 1930's. • I-131 was a huge issue post-WWII both in Japan and nuclear test areas in the USA. • Currently I-131 is a source of major concern at the Fukishima nuclear plant.

  6. History, Uses and Application Continued • I-131, even though harmful in large exposures, has some medicinal uses. • I-131 is currently used as treatment for hyper- thyroidism by destroying tissue with radiation. • Sometimes also used as a radioactive label, but not often since it will destroy tissue in the process.

  7. History, Uses and Application Continued • I-125 which is less harmful has more medicinal uses than I-131. • I-125 is used in brachytherapy which aids in the destruction of cancerous tissues. • I-125 is also used in radiology by tagging antibodies in a radioimmunoassay.

  8. Mode of Entry in Aquatic Environment • I-131 is a nuclear fission product so anywhere fission takes place, I-131 can be found. • Fuel rods in nuclear reactors can crack and release I-131 into the surrounding cooling water, which can be released into the environment. • Another major source of I-131 is nuclear waste, if not correctly sealed will leak into the environment. • A stated before, atomic bomb testing released a lot of I-131 into the atmosphere. • Industrial, medical and university waste can also be sources of I-131.

  9. Toxicity to aquatic life and Toxic effects • I-131 is easily assimilated into the food web by uptake in primary producers such as seaweed. • Shellfish can then bioaccumilate I-131 by filter feeding. • Vertebrates can absorb I-131 readily by the thyroid gland. • Due to radiation, I-131 will lead to tissue destruction and cancer.

  10. Mode of entry and Molecular mode of toxic interaction • As stated before, ingestion is the main mode of entry for most organisms. • If there is a recent explosition or emission of radioactive products, I-131 maybe inhaled as well. • Once in the body, the sodium-iodide symporter, located in the outer cells of the thyroid will actively transport iodide ions inside.

  11. Biochemical metabolism and breakdown • Stimulated by TSH, the thyroid now begins production of Triiodothyronine(T3) and Thyroxine(T4). • To do this, the enzyme thyroperoxidase (TPO) oxidizes the iodide anion and incorporates it into thyroglobin which will later become T3 or T4.

  12. Defense strategies available for detoxification by organism • Most of I-131 can be eliminated in the urine. • If the organism stops the intake of radioactive iodine, it can let the short half-life of the isotope decay it away. • To prevent I-131 uptake entirely, it is possible to saturate the thyroid with stable I-127. • This can be done with KI pills.

  13. Questions?/Bibliography • “Radioactive I-131 from Fallout”http://www.cancer.gov/cancertopics/causes/i131 • “EPA: Radionucleotides, Iodine”http://www.epa.gov/rpdweb00/radionuclides/iodine.html • “Radiotoxicity of Iodine-123, Iodine-125, and Iodine- 131”http://jnm.snmjournals.org/cgi/reprint/33/12/2196.pdf • “Thyroid Disorders”http://www.medicinenet.com/script/main/art.asp?articlekey=54416 • “Seaweed as a model for iodide uptake and retention in the thyroid”http://www.endocrine-abstracts.org/ea/0007/ea0007p237.htm

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