If radiation reaches the United States from the partial meltdowns in Japan, you may need
From Katy Waldman’s Article at Slate – Me, Myself and Iodine -
Of these, the most troubling is iodine-131, which can be absorbed by the thyroid when inhaled, causing thyroid cancer and leukemia. Gases like krypton-85 and xenon-133 don’t interact with bones or tissue, but since they are highly unstable they decay in bursts of radiation that can prove harmful to other bodily systems. But the body tolerates a certain amount of radiation every day, from cosmic rays to watching TV, and it’s only in much larger quantities that the byproducts of a nuclear power plant become dangerous. While radiation spiked to 1,000 times normal levels in one reactor control room, Japanese officials insist that exposure levels outside the plant are not highly hazardous. Even so, area residents have been advised to drink bottled water, stay indoors, and hold washcloths over their noses and mouths. As a precaution against iodine-131, officials have also announced plans to distribute potassium iodide pills, which saturate the thyroid with a stable form of iodine before the more dangerous isotope can be absorbed. They only work, however, if swallowed pre-emptively.
The CDC’s take on it (Centers for Disease Control) -
Following a radiological or nuclear event, radioactive iodine may be released into the air and then be breathed into the lungs. Radioactive iodine may also contaminate the local food supply and get into the body through food or through drink. When radioactive materials get into the body through breathing, eating, or drinking, we say that “internal contamination” has occurred. In the case of internal contamination with radioactive iodine, the thyroid gland quickly absorbs this chemical. Radioactive iodine absorbed by the thyroid can then injure the gland. Because non-radioactive KI acts to block radioactive iodine from being taken into the thyroid gland, it can help protect this gland from injury.
This is Wikipedia’s take on it -
SSKI may be used in radioiodine-contamination emergencies (i.e., nuclear accidents) to “block” the thyroid’s uptake of radioiodine (this is not the same as blocking the thyroid’s release of thyroid hormone).
Potassium iodide was approved in 1982 by the US FDA to protect the thyroid glands from radioactive iodine from accidents or fission emergencies. In the event of an accident or attack at a nuclear power plant, or fallout from a nuclear bomb, volatile fission product radionuclides may be released, of which 131I is one of the most common by-products and a particularly dangerous one due to thyroid gland concentration of it, which may lead to thyroid cancer. By saturating the body with a source of stable iodide prior to exposure, inhaled or ingested 131I tends to be excreted.
Potassium iodide cannot protect against any other causes of radiation poisoning, nor can it provide any degree of protection against dirty bombs that produce radionuclides other than isotopes of iodine. …