# Radioactive Iodine 131, 127, Treatment, Exposure And Lag Time Until Thyroid Cancer After Exposure

http://youtu.be/rCyyZwyCoxk

Radioactive Iodine is a harsh treatment that should be a last resort in most cases. If you have Graves’ Disease, or any other hyperthyroid disorder, and are considering receiving radioactive iodine, there are other treatment options that you will want to consider first. This video will show you the potential consequences of receiving RAI, and what other options you may have to choose from.
Per Wikipedia; “Iodine-131 (131I), also called radioiodine is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. It is associated with nuclear energy, medical diagnostic and treatment procedures, and natural gas production. It also plays a major role as a radioactive isotope present in nuclear fission products, and was a significant contributor to the health hazards from open-air atomic bomb testing in the 1950s, and from the Chernobyl disaster, as well as being a large fraction of the contamination hazard in the first weeks in the Fukushima nuclear crisis. This is because I-131 is a major uraniumplutonium fission product, comprising nearly 3% of the total products of fission (by weight). See fission product yield for a comparison with other radioactive fission products. I-131 is also a major fission product of uranium-233, produced from thorium.
Due to its mode of beta decay, iodine-131 is notable for causing mutation and death in cells that it penetrates, and other cells up to several millimeters away. For this reason, high doses of the isotope are sometimes less dangerous than low doses, since they tend to kill thyroid tissues that would otherwise become cancerous as a result of the radiation. For example, children treated with moderate dose of I-131 for thyroid adenomas had a detectable increase in thyroid cancer, but children treated with a much higher dose did not. Likewise, most studies of very-high-dose I-131 for treatment of Graves disease have failed to find any increase in thyroid cancer, even though there is linear increase in thyroid cancer risk with I-131 absorption at moderate doses.[1] Thus, iodine-131 is increasingly less employed in small doses in medical use (especially in children), but increasingly is used only in large and maximal treatment doses, as a way of killing targeted tissues. This is known as “therapeutic use.”
Iodine-131 can be “seen” by nuclear medicine imaging techniques (i.e., gamma cameras) whenever it is given for therapeutic use, since about 10% of its energy and radiation dose is via gamma radiation. However, since the other 90% of radiation (beta radiation) causes tissue damage without contributing to any ability to see or “image” the isotope, other less-damaging radioisotopes of iodine are preferred in situations when only nuclear imaging is required. The isotope I-131 is still occasionally used for purely diagnostic (i.e., imaging) work, due to its low expense compared to other iodine radioisotopes. Very small medical imaging doses of I-131 have not shown any increase in thyroid cancer. The low-cost availability of I-131, in turn, is due to the relative ease of creating I-131 by neutron bombardment of natural tellurium in a nuclear reactor, then separating I-131 out by various simple methods (i.e., heating to drive off the volatile iodine). By contrast, other iodine radioisotopes are usually created by far more expensive techniques, starting with reactor radiation of expensive capsules of pressurized xenon gas.
Iodine-131 is also one of the most commonly used gamma-emitting radioactive industrial tracer. Radioactive tracer isotopes are injected withhydraulic fracturing fluid to determine the injection profile and location of fractures created by hydraulic fracturing.[2]
Much smaller incidental doses of iodine-131 than those used in medical therapeutic procedures, are thought to be the major cause of increased thyroid cancers after accidental nuclear contamination.[3][4][5][6] These cancers happen from residual tissue radiation damage caused by the I-131, and usually appear years after exposure, long after the I-131 has decayed.[3]

## Production

Most I-131 production is from nuclear reactor neutron-irradiation of a natural tellurium target. Irradiation of natural tellurium produces almost entirely I-131 as the only radionuclide with a half-life longer than hours, since most lighter isotopes of tellurium become heavier stable isotopes, or else stable iodine or xenon. However, the heaviest naturally-occurring tellurium nuclide, Te-130 (34% of natural Te) absorbs a neutron to become tellurium-131, which beta-decays with a half-life of 25 minutes, to I-131.
A tellurium compound can be irradiated while bound as an oxide to an ion exchange column, and evolved I-131 then eluted into an alkaline solution.[7]More commonly, powdered elemental tellurium is irradiated and then I-131 separated from it by dry distillation of the iodine, which has a far higher vapor pressure. The element is then dissolved in a mildly alkaline solution in the standard manner, to produce I-131 as iodide and hypoiodate (which is soon reduced to iodide).[8]
131I is a fission product with a yield of 2.878% from uranium-235,[9] and can be released in nuclear weapons tests and nuclear accidents. However, the short half-life means it is not present in significant quantities in cooled spent nuclear fuel, unlike iodine-129 whose half-life is nearly a billion times that of I-131.

Iodine-131 decay scheme (simplified)

I-131 decays with a half-life of 8.02 days with beta minus and gamma emissions. Thisnuclide of iodine has 78 neutrons in its nucleus, while the only stable nuclide, 127I, has 74. On decaying, 131I most often (89% of the time) expends its 971 keV of decay energy by transforming into the stable 131Xe (Xenon) in two steps, with gamma decay following rapidly after beta decay:
${^{131}_{53}\mathrm{I}} \rightarrow \beta + \bar{\nu_e} + {^{131}_{54}\mathrm{Xe}^*}$ + 606 keV
${^{131}_{54}\mathrm{Xe}^*} \rightarrow {^{131}_{54}\mathrm{Xe}} + \gamma$ + 364 keV
The primary emissions of 131I decay are thus electrons with a maximal energy of 606 keV (89% abundance, others 248–807 keV) and 364 keV gamma rays (81% abundance, others 723 keV).[10] Beta decay also produces an antineutrino, which carries off variable amounts of the beta decay energy. The electrons, due to their high mean energy (190 keV, with typical beta-decay spectra present) have a tissue penetration of 0.6 to 2 mm.[11]

## Effects of exposure

Per capita thyroid doses in the continental United States resulting from all exposure routes from all atmosphericnuclear tests conducted at the Nevada Test Site from 1951-1962. A Centers for Disease Control and PreventionNational Cancer Institute study claims that nuclear fallout might have led to approximately 11,000 excess deaths, most caused by thyroid cancer linked to exposure to iodine-131.[12]

Iodine in food is absorbed by the body and preferentially concentrated in the thyroid where it is needed for the functioning of that gland. When 131I is present in high levels in the environment from radioactivefallout, it can be absorbed through contaminated food, and will also accumulate in the thyroid. As it decays, it may cause damage to the thyroid. The primary risk from exposure to high levels of 131I is the chance occurrence of radiogenic thyroid cancer in later life. Other risks include the possibility of non-cancerous growths and thyroiditis.[1]
The risk of thyroid cancer in later life appears to diminish with increasing age at time of exposure. Most risk estimates are based on studies in which radiation exposures occurred in children or teenagers. When adults are exposed, it has been difficult for epidemiologists to detect a statistically significant difference in the rates of thyroid disease above that of a similar but otherwise-unexposed group.[1]
The risk can be mitigated by taking iodine supplements, raising the total amount of iodine in the body and, therefore, reducing uptake and retention in the face and chest and lowering the relative proportion of radioactive iodine. However, such supplements were not distributed to the population living nearest to the Chernobyl nuclear power plant after the disaster,[13] though they were widely distributed to children in Poland.
Within the USA, the highest 131I fallout doses occurred during the 1950s and early 1960s to children having consumed fresh sources of milk contaminated as the result of above-ground testing of nuclear weapons.[3] The National Cancer Institute provides additional information on the health effects from exposure to 131I in fallout,[14] as well as individualized estimates, for those born before 1971, for each of the 3070 counties in the USA. The calculations are taken from data collected regarding fallout from the nuclear weapons tests conducted at the Nevada Test Site.[15]
On 27 March 2011, the Massachusetts Department of Public Health reported that 131I was detected in very low concentrations in rainwater from samples collected in Massachusetts, USA, and that this likely originated from the Fukushima power plant.[16] Farmers near the plant dumped raw milk, while testing in the United States found 0.8 pico-curies per liter of iodine-131 in a milk sample, but the radiation levels were 5,000 times lower than the FDA’s “defined intervention level.” The levels were expected to drop relatively quickly[17]

## Medical and pharmaceutical uses

pheochromocytoma tumor is seen as a dark sphere in the center of the body (it is in the left adrenal gland). The image is byMIBG scintigraphy, showing the tumor by radiation from radioiodine in the MIBG. Two images are seen of the same patient from front and back. The image of the thyroid in the neck is due to unwanted uptake of radioiodine (as iodide) by the thyroid, after breakdown of the radioactive iodine-containing medication. Accumulation at the sides of the head is from salivary gland uptake of radioiodide. Radioactivity is also seen from uptake by the liver, and excretion by the kidneys with accumulation in the bladder.

It is used in nuclear medicine therapeutically and can also be seen with diagnostic scanners if it has been used therapeutically. Use of the 131I as iodide salt exploits the mechanism of absorption of iodine by the normal cells of the thyroid gland. Examples of its use in radiation therapy are those where tissue destruction is desired after iodine uptake by the tissue.
Major uses of 131I include the treatment of thyrotoxicosis (hyperthyroidism) and some types of thyroid cancer that absorb iodine. The 131I is thus used as direct radioisotope therapy to treat hyperthyroidism due to Graves’ disease, and sometimes hyperactive thyroid nodules (abnormally active thyroid tissue that is not malignant). The therapeutic use of radioiodine to treat hyperthyroidism from Graves’ disease was first reported by Saul Hertz in 1941.
The 131I isotope is also used as a radioactive label for certain radiopharmaceuticals that can be used for therapy, e.g. 131I-metaiodobenzylguanidine (131I-MIBG) for imaging and treating pheochromocytoma and neuroblastoma. In all of these therapeutic uses, 131I destroys tissue by short-range beta radiation. About 90% of its radiation damage to tissue is via beta radiation, and the rest occurs via its gamma radiation (at a longer distance from the radioisotope). It can be seen in diagnostic scans after its use as therapy, because 131I is also a gamma-emitter.
Because of the carcinogenicity of its beta radiation in the thyroid in small doses, I-131 is rarely used primarily or solely for diagnosis (although in the past this was more common due to this isotope’s relative ease of production and low expense). Instead the more purely gamma-emitting radioiodine iodine-123 is used in diagnostic testing (nuclear medicine scan of the thyroid). The longer half-lived iodine-125 is also occasionally used when a longer half-life radioiodine is needed for diagnosis, and, in brachytherapy treatment (isotope confined in small seed-like metal capsules), where the low-energy gamma radiation without a beta component, makes iodine-125 useful. The other radioisotopes of iodine are never used in brachytherapy.
The use of 131I as a medical isotope has been blamed for a routine shipment of biosolids being rejected from crossing the Canada—U.S. border.[32] Such material can enter the sewers directly from the medical facilities, or by being excreted by patients after a treatment.

Because the total radioactivity of a dose of I-131 is usually high, and because the local beta radiation of nearby stomach tissue from an undissolved capsule is high, I-131 is usually administered to human patients in a small drink containing a few ounces of fluid. This is often slowly and carefully sucked out of a shielded container to prevent spillage.[33] For administration to animals (for example, cats with hyperthyroidism) for practical reasons the isotope must be administered by injection.

### Post-treatment isolation

Patients receiving I-131 radioiodine treatment are warned not to have sexual intercourse for one month (or shorter, depending on dose given), and women are told not to become pregnant for six months afterwards. “This is because a theoretical risk to a developing fetus exists, even though the amount of radioactivity retained may be small and there is no medical proof of an actual risk from radioiodine treatment. Such a precaution would essentially eliminate direct fetal exposure to radioactivity and markedly reduce the possibility of conception with sperm that might theoretically have been damaged by exposure to radioiodine.”[34] These guidelines vary from hospital to hospital and will depend also on the dose of radiation given. Some also advise not to hug or hold children when the radiation is still high, and a one or two metre distance to others may be recommended.[35]
I-131 will be eliminated from the body over the next several weeks after it is given. The majority of I-131 will be eliminated from the human body in 3–5 days, through natural decay, and through excretion in sweat and urine. Smaller amounts will continue to be released over the next several weeks, as the body processes thyroid hormones created with the I-131. For this reason, it is advised to regularly clean toilets, sinks, bed sheets and clothing used by the person who received the treatment. Patients may also be advised to wear slippers or socks at all times, and themselves physically isolated from others. This minimizes accidental exposure by family members, especially children.[36] Use of a decontaminant specially made for radioactive iodine removal may be advised. The use of chlorine bleach solutions, or cleaners that contain chlorine bleach for cleanup, are not advised, since radioactive elemental iodine gas may be released.[37] Airborne I-131 may cause a greater risk of second-hand exposure, spreading contamination over a wide area.
Many airports now have radiation detectors to detect the smuggling of radioactive materials that may be used in nuclear weapons manufacture. Patients should be warned that if they travel by air, they may trigger radiation detectors at airports up to 95 days after their treatment with 131I.[38]

Used for the first time in 1951 to localize leaks in a drinking water supply system of Munich, Germany, iodine-131 became one of the most commonly used gamma-emitting industrial radioactive tracer with applications in isotope hydrology and leak detection.[39][40][41][42]
Since late 1940s, radioactive tracers have been used by the oil industry. Tagged at the surface, water is then tracked downhole, using the appropriated gamma detector, to determine flows and detect underground leaks. I-131 has been the most widely used tagging isotope in an aqueous solution of sodium iodine.[2][43][44] It is used to characterize the hydraulic fracturing fluid to help determine the injection profile and location of fractures created by hydraulic fracturing.[45][46][47]
Dr. John Apsley has spoken about the effects of radioactive iodine exposure on thyroid function. Once radioactive iodine hits the thyroid its function is impaired which in turn suppresses the immune system, he explains. CDC data shows a significant increase in death rates attributable to radioactive iodine given off by the Fukushima disaster, he adds.
Dr. Apsley is concerned that increased deaths in infants and the elderly will follow wherever rain dumps radioactive iodine downwind from any nuclear accident, including the US, after Fukushima Daichi melted down and out on 3/11.. Apsley also reveals how a relatively inexpensive assortment of dietary supplements can quench the effects of radioactive particles.
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Radioactive Iodine 131, 127, Treatment, Exposure And Lag Time Until Thyroid Cancer After Exposure; via @AGreenRoad

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