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|04-07-2007, 07:07 AM||#1|
Join Date: Oct 2004
Location: Northern Georgia
Iodine blockers in nuclear fallout areas by Flighterdoc
Use of Iodine blockers in nuclear fallout environments
What is KI and why do we need it? KI is the chemical symbol for Potassium Iodide. Another product with a similar effect is Potassium Iodate (KIO3)
One of the products of fallout (actually, product of decay of higher atomic weight radioactive materials) is a radioactive form of Iodine, Iodine-131. The thyroid gland takes iodine from your diet, and uses it to make a hormone that is essential as a raw material for a LOT of things in the way cells process raw materials to make other materials. You can’t live without the various thyroid hormones that are produced, you can however live without a thyroid, as long as you take a thyroid supplement. BTW, it’s almost impossible to overdose on iodine (with a normal diet), since it’s water soluble – you just eliminate excesses of it.
Now, if you're exposed to I-131, your thyroid gland will happily use it, just like any other source of iodine. Since it's radioactive, though, the iodine will irradiate your thyroid gland (with beta particles, if anyone is interested) and do bad things to it. Beta particles are not particularly strong, on the skin they cause slight burns that look and feel like sunburn. However, in the thyroid, the beta particles can get into the thyroid cells and kill them, or cause the DNA in the nucleus to not duplicate correctly during mitosis (a mutation), or worse, cause them to start growing wildly. These last two conditions are what we call 'cancer'.
While your thyroid gland will be very happy using radioactive Iodine, it will also be very happy using non-radioactive iodine. And, it really doesn’t use a LOT of iodine in either case. So, if you can 'flood' your thyroid and system with non-radioactive iodine prior to exposure to the bad stuff, the radioactive excess will just be eliminated from your body.
Since you need your thyroid (or the products from the thyroid) to live, having it stop working is bad. Fortunately (I guess) it takes usually 10 years or more for such a cancer to develop, following a major nuclear release (Hiroshima/Nagasaki, Chernobyl).
Radioactive materials have 'half lives'. This is the time it takes for 1/2 of the radioactive atoms in a substance to release their energy and become something else. People worry about elements that have a very long half-life (plutonium, for instance, has an isotope with a half-life of 25,000 years) but the immediate threat are isotopes that have a very short half life. An analogy may be helpful:
Keep in mind that when something is radioactive, it's emitting energy (like heat, or light). That energy has to go somewhere and do something, the central dogma of physics is that energy cannot be created or destroyed, only changed in form. So, that energy is what causes the damage to your thyroid.
A mass of radioactive material is like a pan of popcorn kernels, waiting to pop. The popping is the release of the energy, and the conversion from one element to another (I-131 turns into xenon, which is stable. Uranium-238, for example, ultimately (after more than 4.5 billion years) turns into lead). Now, picture your standing over the stove, with your Jiffy-Pop™ - what has more energy, a pan where half the kernels pop (release energy) in 10 milliseconds (some weird isotopes are even shorter lived that that), or one that takes 25,000 years to pop HALF the kernels? And another 25,000 years to pop half of the remaining unpopped kernels (so, you now have 75% of the kernels popped), and another 25,000 years for half of the remaining 25% (87.5% total popped)? Of course, the ones that release their energy quickly are the more 'energetic' ones.
I-131 has a half life of about 8 days. Normally, we like to say that 10 half-lives are necessary to reduce the amount of radiation to a negligible level, or 80 days. This would reduce the radiation by a factor of 2 to the 10th power, or 1/1024 of the original amount, a very significant amount.
Now, why do people get so worked up about radioactive iodine in the thyroid? Well, it's a significant threat (at least 10 years or so post exposure), and it's very easily preventable (just stock and take some sort of thyroid iodine blocker).
So, which form is better? Any of them will probably do about as good a job, but only one form has been approved by the FDA - the one that tastes so bad you might vomit after tasting it.
If you’re exposed to fallout, taking an Iodine preparation is probably a good idea. You should take it for 90 days after the radioactive iodine is released, to ensure that 10 half-lives have deteriorated. Follow the dosing schedule on the package, which should be something along the lines of:
Over 12 years old 130mg KI, 170mg KIO3
3 - 12 years old 65mg KI 85mg KIO3
1 - 36 months old 32mg KI, 42mg KIO3
< 1 month old 16mg KI, 21mg KIO3
World Health Organization, Guidelines for Iodine Prophylaxis following Nuclear Accidents, Update 1999
Since the KI or KIO3 is water soluble, there is NO benefit in taking an extra dose
Since the KI or KIO3 ONLY protects the thyroid gland, it does NOT protect any body parts against any other types of radiation exposure. It is not an ‘invincibility pill”.
What about other radiation exposure? What happens if you’re not in a shelter during the worst part of the fallout. Fallout decays in strength about 10% for every 7 hours post peak. So, if you're in a shelter with a monitor and notice a peak in the reading outside, 7 hours later the reading will be 10% less, 14 hours later it will be 10% of 90% less, etc. So, the conventional wisdom is that if you shelter for about 14 days (7x7x7 hours) you will get only 1/1,000 (10x10x10) the exposure had you been there at the peak.
If the exposure was high (say, 1,000 Roentgen (R)/Hr peak), after 2 weeks you would only be getting 1 rad/hour. At this level you can go outside for an hour or two and take care of animals, get more food or water, etc. You may need to stay in the shelter longer, and probably should sleep in the shelter for awhile longer, but the longer since the peak in radiation, the more 7 hour periods that the radiation is decaying, too. If you were to stay in shelter for say 100 days (7x7x7x7x7 hours) the radiation outside (1,000 R total) would be 1/10,000 (10x10x10x10) or 0.1 R/hour.
Now, peacetime limits are quite strict, but a dose of as much as 50R total (RAD, or Roentgen absorbed dose), 10 times the peacetime annual standard for nuclear workers probably isn't going to cause much trouble for anyone. That would be exposure to 1 R for 50 hours, or exposure to 5 R for 10 hours, etc. At 100 RAD there is less than a 50% chance of slight clinical symptoms of radiation exposure, and it takes as much as 200 RAD to cause significant health issues, especially for older people (who, frankly, have less time left to develop a long-term cancer).
Nobody (especially me) wants to see a nuclear war or release of nuclear materials. However, if people actually learn the truth about nuclear weapons affects (such as the info above) the ability of such weapons to terrorize would be far less. Unfortunately (political speech coming), there are many who will use ignorance to further their own agendas and make claims that cause people to be misled - such as the specious claim that you cant protect yourself from radiation, or that fallout will kill everyone on earth.
Hope this helps.
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