Iodine
Iodine is a chemical element, having the chemical symbol I.
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Its atomic number (the number of protons) is 53. It has a Standard Atomic Weight of 126.90447(3), and is typically found as a solid in its elemental form.
Iodine is considered to be a member of the "Halogen" class of elements, has a boiling point of 184.4 °C , and a melting point of 113.7 °C .
Iodine is specified as a List I chemical by the US Drug Enforcement Administration and is considered to have high risk of diversion to illicit drug manufacturing.[1]
Radioactive iodine-131
Several isotopes of iodine, including 123I, 124I, 129I and 131I are radioactive isotopes of iodine used to treat certain cancers or for medical imaging processes [2][3] and 131
131I has been produced from: [4]
- Nuclear weapons production and atmospheric testing
- Deliberate production for medical use
- Nuclear fission in nuclear energy facilities, and released through accidents such as Three Mile Island
In fact, both 129I and 131 are produced by fission reactions of uranium in nuclear energy facilities or by detonation of nuclear weapons. 131I has a half-life of only 8.06 days[5], so environmental spills are of much less concern that similar spills of other radioactive elements such as cesium or uranium.
However, 129I has a half-life of 15.7 million years.[6] Thus, a spill of 131I one thousand times the normal background would decay back to normal levels in about 81 days. The 129I and 131I atoms emit beta particles and emit gamma radiation during radioactive decay. Because iodine is readily absorbed by the thryroid gland, which uses it to produce thyroid hormones, ingestion of radioactive iodine can lead to thyroid pathology, including thyroid cancer.
Ingestion
Like bromine, iodine is readily sublimed, going from the solid state directly to the gaseous state,(skipping the liquid state) so exposure to the solid form can still lead to inhalation of the chemical. Being a halogen, it also readily forms many salts which are readily soluble, so the molecular form is quickly converted into various salts upon reaction with most environments. Dairy animals exposed to any form of radioactive iodine can thus lead to ingestion by humans.
References
- ↑ http://www.deadiversion.usdoj.gov/fed_regs/rules/2007/fr0702.htm
- ↑ http://www.nejm.org/doi/full/10.1056/NEJMoa041511#t=articleBackground
- ↑ http://www.medscape.com/viewarticle/477675
- ↑ Radiation Exposure from Iodine 131: Exposure Pathways, Agency for Toxic Substances and Disease Registry
- ↑ http://www.bt.cdc.gov/radiation/isotopes/pdf/iodine.pdf
- ↑ http://www.epa.gov/radiation/radionuclides/iodine.html#wheredoes