Radiation is awful stuff. Whether originating from a nuclear weapon, an accident, a reactor release, or a spill in a medical lab, it can cause tumors, cancers and death. For most people, no matter the cause, the real danger is a potentially deadly toxin called radioactive iodine (RAI). If released, it can travel hundreds of miles on the wind, contaminating food and water as it passes. And worse, it’s invisible.
Fortunately, there is a pill that can protect all of us against RAI. Known as KI or potassium iodide, this simple, economical, over-the-counter medicine blocks RAI from entering the body. There’s only one problem – to be effective, it should be taken as quickly as possible.
Three RAI Releases: The world has seen three major releases of RAI—the bombings in Japan during World War II, atomic testing during the 1950’s, and the disaster at the Chernobyl nuclear power plant in 1986. All three proved that RAI, and only RAI, could threaten millions of people over a wide area. Radioactive fallout from the bombs and tests caused thyroid damage and cancer throughout Japan, on Pacific islands hundreds of miles downwind of the test sites, and among tens of thousands of Americans as a result of testing in Nevada. The World Health Organization documented thyroid cancer hundreds of kilometers from the Chernobyl reactor, and the US Nuclear Regulatory Commission (NRC) found that (ten years after the Chernobyl accident) thyroid damage appeared to be the only medically significant effect from the accident outside of the blast area. They also found that the “vast majority” of cancers occurred “more than 50 km from the site.” In fact, almost all took place between 30 and 200 miles downwind of the reactor.
FDA Approved: Fortunately, RAI can be effectively neutralized by the prompt use of an over-the-counter pharmaceutical known as potassium iodide (KI). The Food and Drug Administration approved the drug in 1981, noting that KI provided “safe and effective protection against thyroid cancer caused by irradiation” and its use in a radiological emergency has been supported by virtually every scientific group that has ever studied the issue.
How Does KI Work? KI works by saturating the thyroid with non-radioactive or what’s called “cold” iodine. Consequently, when radioactive or “hot” iodine enters the body, it can not be absorbed by the thyroid and passes harmlessly from the body.
How Much KI Do I Need? KI is most effective when taken prior to any exposure, but anyone in a contaminated area can reduce the total amount of RAI absorbed by starting KI administration as soon as possible—even after initial exposure has occurred. Because radiation danger is cumulative, daily KI dosing will prevent any RAI from being absorbed during the danger period even if it is begun after the initial exposure.
The danger posed by RAI is limited and highly defined by its 8.1 day half-life. RAI decays rapidly, and after 7 half-life cycles (about 60 days) 99% of the RAI will no longer be dangerous. Consequently, in heavily irradiated areas closest to the release point, the threat might linger for as long as two months. However, as the distance from the release area increases, the RAI is diluted and the level of radiation diminishes. Consequently, less KI is needed. The following chart provides some guidance:
| Distance From Release Point | Number of Tablets Required (per person) |
| 1 to 25 miles | 40 to 60 tablets |
| 25 to 50 miles | 20 to 40 tablets |
| 50 to 100 miles | 6 to 20 tablets |
| Beyond 100 miles | 2 to 6 tablets |
Has KI Ever Been Used on a Wide Basis? Yes. The Chernobyl Nuclear Power Plant is located near the Ukrainian city of Pripyat. Following the accident, KI was distributed throughout the city. According to the United States Nuclear Regulatory Commission, which conducted an extensive examination of Chernobyl, “the use of KI reported by the Pripyat population was credited with permissible iodine content found in 97% of the 206 evacuees tested at one relocation center.” Similarly, Poland, which shares a border with the Ukraine, distributed KI to more than 17 million people. As a result, Poland was the only country exposed to radiation because of Chernobyl that had no known cancers attributable to the accident. Unfortunately, KI was not available throughout the region. The NRC report found that throughout the Ukraine, Belarus, and Russia, where KI was not used, thyroid cancer has spiked to epidemic levels. By 1999, the World Health Organization identified more than 11,000 cases of thyroid cancer attributable to Chernobyl, primarily between 30 and 200 miles from the reactor.
Does KI Have Any Side Effects? KI has two drawbacks. First, in liquid form, KI can be a severe gastric irritant, and it is difficult to store and distribute due to its weight and sensitivity to environmental conditions. Further, careful measurement to avoid overdosing is required, especially when used by young children. Dosage of the liquid must be adjusted using an eye-dropper which must be stored with the product.
Fortunately, KI tablets do not share these drawbacks. They do not cause gastric distress and overdosing is almost impossible since the product is pre-measured and splits easily into halves and quarters for young children. The tablets are small, lightweight and environmentally insensitive, making them easy to store and distribute in an emergency.
Second, to be effective, KI must be taken as early as possible, and additional dosages must be taken until all RAI has disappeared. Consequently, it is important that KI be readily available throughout the country.
Is KI Expensive? No. A single tablet costs less than 30 cents. A six-pack of KI tablets costs between $1.50 and $1.80 per pack and has a shelf life of 10 years. The entire nation could be protected with an expenditure of $400 to $500 million.
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