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Potassium Iodide: How Iodine Pills Protect Against Radiation

With a degree in biochemistry, Leah works for a small biotechnology company and enjoys writing about science.

Potassium Iodide fills the thyroid gland, preventing the uptake of the radioactive form of Iodine. Click to enlarge.

Potassium Iodide fills the thyroid gland, preventing the uptake of the radioactive form of Iodine. Click to enlarge.

Potassium Iodide: What Is It?

Potassium Iodide is a chemical with the formula KI, containing a positively charged Potassium ion and a negatively charged Iodine ion. Potassium Iodide is the ingredient added (in low levels) to iodized salt and is also the chemical in the non-prescription Iodine pills used for radiation exposure.

Potassium Iodide for protection against radiation exposure comes in liquid form and pill form. In the United States, the two FDA-approved brands for adults are Iostat ® (Anbex, Inc.) and Thyro-Block ® (Medpointe, Inc.). Thyrosafe ® (Recip US) is the FDA-approved liquid form of Potassium Iodide manufactured at a lower dosage for children or others with low body weight. The liquid form is generally formulated for young children.

Who Should Have Potassium Iodide Pills?

The U.S. Nuclear Regulatory Commission recommends that any individual living within 10 miles of a nuclear power facility should keep Potassium Iodide pills on-hand in case of an accidental meltdown.

In the wake of the 2011 nuclear power plant meltdown in Fukushima, Japan, many individuals on the West Coast of the United States rushed out to purchase Potassium Iodide pills. This eliminated many stores' stockpiles of the drug and would not provide any protection since the radiation from the Japanese meltdown would not reach the United States in sufficient quantities to cause a health problem. In fact, taking Potassium Iodide pills when there is no need can cause serious health problems, particularly for pregnant and lactating women.

The Fukushima Nuclear Power Plant Chimneys

The Fukushima Nuclear Power Plant Chimneys

How Does Potassium Iodide Work Against Radiation?

In the event of a nuclear power plant meltdown (or other radioactive event), two radioactive forms of Iodine are released: I-129 and I-131. While I-131 is radioactive, it has a very short half-life of 8 days. This means that I-131 will be completely cleared from the environment in a matter of months.

Unfortunately, I-129 is highly radioactive and has a half-life of 15.7 million years: after a nuclear power plant meltdown, it will stay in the environment for a very long time.

The human thyroid will absorb Iodine indiscriminately. If radioactive isotopes of Iodine are inhaled or consumed, the thyroid will take up the isotopes. This radiation is likely to cause cancer, particularly in infants and children. People over the age of 60 are at a lower risk of developing thyroid cancer from radioactive Iodine isotopes.

Fortunately, the human thyroid will only take up a certain amount of Iodine. By giving people Potassium Iodide (a safe version of Iodine), the thyroid fills its receptor sites with the safe version of the element. When the individual is exposed to the radioactive Iodine isotopes, the thyroid cannot take it up, as its Iodine receptors are filled with Potassium Iodide. In this way, the radioactive material passes safely through the body without being taken up by the thyroid. Potassium Iodide pills work best when used within 3-4 hours of exposure.

Why Iodized Salt is Not Sufficient

After the Fukushima Nuclear Power plant incident in March 2011, Chinese citizens began purchasing and hoarding iodized salt. Unfortunately, iodized salt does not contain enough Iodine to prevent radiation poisoning. Even if a person ate 2Kg of iodized salt, they would still not have sufficient Iodine to protect against radiation poisoning. Natural kelp extracts of Iodine are likewise insufficient to meet the needs of those exposed to radiation. The pharmaceutical-grade Potassium Iodide pills are specifically formulated with the proper dose of KI to prevent radiation sickness, and these tablets are the only method for obtaining the proper dose.

Thyroid cancer in a man.

Thyroid cancer in a man.

How Radioactive Iodine Enters the Body

Radioactive Iodine isotopes enter the body through the respiratory and digestive systems. After a nuclear meltdown, the initial route of exposure is generally airborne: people breathe in the radioactive Iodine, and it enters the bloodstream, where it travels to the thyroid.

The long-term exposure danger is through consuming radioactive Iodine. A large increase in thyroid cancer was detected among people who were children and adolescents at the time of the Chernobyl disaster. Radioactive iodine was deposited into the fields and pastures around the nuclear meltdown site, where cows consumed the contaminated grass. Children drank the milk produced by these cows, and the contaminated milk entered their bodies through the gastrointestinal system. Approximately 5,000 cases of thyroid cancer have been diagnosed in exposed children in Ukraine, Belarus, and the Russian Federation.

While Poland was within the fallout range of the Chernobyl disaster, the country provided Potassium Iodide to its citizens. Poland has not seen an increase in thyroid cancer rates, demonstrating that the distribution and use of KI pills is highly effective in protecting victims of radiation exposure.

Where to Buy Potassium Iodide

Potassium Iodide may be purchased directly through the manufacturer or through other online retailers. The drug is over-the-counter, which means no prescription is required. Potassium Iodide should not be taken when there has been no exposure to radiation. Consult a doctor before taking Potassium Iodide pills.

The Dangers of Taking Potassium Iodide Without a Cause

Potassium Iodide is not free from side effects. While Potassium Iodide pills benefit those immediately exposed to radioactive Iodine isotopes, it is not recommended for casual use.

Individuals with an Iodine allergy may have a severe reaction to Potassium Iodide. In infants, Potassium Iodide may cause skin rash and thyroid problems. Potassium Iodide may make conditions associated with Tuberculosis worse and can increase the levels of Potassium in the blood: a danger to patients with kidney dysfunction. Potassium Iodide may interfere with other drugs, including Warfarin, Dicumarol, and Acenocoumarol. Breastfeeding mothers will pass the drug along to their newborn infants, and long-term use among pregnant women may cause congenital iodide goiter.

People over the age of 40 will not take up the radioactive Iodine as readily as younger individuals. Potassium Iodide pills are not required for people over the age of 40 unless extremely high radiation levels are encountered. Children and adolescents are at the highest risk of exposure to radioactive Iodine.

Why Prevention of Thyroid Cancer is Necessary

Most people survive thyroid cancer: in the United States, over 90% of affected people become cancer-free after treatment. Some may wonder why there is much anxiety surrounding the potential for the disease from nuclear fallout.

Unfortunately, the post-Chernobyl thyroid cancers were atypical, affecting children under the age of 10 years with an aggressive form of the disease. The cancer survivors may redevelop cancer at a later time and will require monitoring and testing for the rest of their lives. The cost and health damage to these children was permanent: a simple preventive treatment with Potassium Iodide would have spared them from the significant health issues associated with having thyroid cancer at a young age.

© 2011 Leah Lefler


Leah Lefler (author) from Western New York on April 01, 2011:

It is useful for those exposed to radiation, particularly if the individual exposed is a child or adolescent. Of course, people who have not been exposed to radiation should avoid taking the high doses used in the pills (they can cause problems in pregnant mothers or with breastfeeding infants).

kafsoa on April 01, 2011:

It was really useful to know how important is potassium iodide.

Leah Lefler (author) from Western New York on April 01, 2011:

Potassium Iodide does a pretty good job at protecting people from radioactive iodine. Unfortunately, it can't protect against all of the other radioactive isotopes. Still, saving an entire generation from thyroid cancer is a good thing. I think about the heroes inside of the Fukushima power plant every day - they are exposing themselves to high levels of radiation to stop the leakage. They are really amazing, courageous people!

Tim Mitchell from Escondido, CA on April 01, 2011:

Very good article. I live near San Onofre power Plant in the San Diego area. I never thought to keep those around. However, I do know a good source for French Green Clay, which is used for detoxing radiation exposure. It will be intereting to learn how they deal with the long term exposure in Japan. A tragedy beyond my scope of words other than "sad."

Thank you, Leahlefler, for making this information available.

Tim Mitchell from Escondido, CA on April 01, 2011:

Very good article. I live near San Onofre power Plant in the San Diego area. I never thought to keep those around. However, I do know a good source for French Green Clay, which is used for detoxing radiation exposure. It will be intereting to learn how they deal with the long term exposure in Japan. A tragedy beyond my scope of words other than "sad."

Thank you, Leahlefler, for making this information available.

TajSingh from United Kingdom on March 31, 2011:

Interesting. I did not know that potassium iodide protects against radiation. Very informative stuff. Thanks for sharing!

Leah Lefler (author) from Western New York on March 31, 2011:

And obviously, people in the US should not run out and buy the tablets: I clearly discuss this in the second paragraph, and in the second-to-last paragraph - it should only be taken when recommended by local health authorities. The adult dose is 130mg, and only costs about $20 - not exactly likely to break the bank. I'm not sure who in the world is paying $600 on ebay - the stuff is available on amazon for a small amount of money (and distributed for free to those in immediate danger of thyroid involvement). The lower dose formulations are for children, who are the ones most likely to develop a problem from the radioactive iodine (adults over forty are generally safe from the radioactive iodine exposure).

Leah Lefler (author) from Western New York on March 31, 2011:

You obviously did not read the article in entirety: the recommended adult dose of KI for those exposed to radiation is 130mg. An adult would have to consume 3 1/2 pounds of iodized salt to confer this quantity of KI:

There are several sources for this information, but basic chemistry demonstrates the amount of KI added to iodized salt is insufficient for those exposed to radiation.

RunAbstract from USA on March 30, 2011:

Well I suppose there is debate over this issue. What I am saying is why are people here in the USA spending SO MUCH MONEY for tablets when: #1 we are not in danger at the moment, and #2 when we get a steady intake of potassium iodide from table salt?

We aren't near the danger in Japan. (God help those who are). So why has the media done such a hoop-la fear job about these pills?

Also if the above is true, what's so bad about a tablespoon of table salt? Sure a preson on a restricted salt diet may not be able to have that much salt, but I believe for others it would be safe.

I think fear is a HUGE motivator, and that certain companies use the public's fear to increase sales. We sure didn't hear much about potassium iodide before this situation in Japan. And I for one live relatively close to a nuclear power plant. Why has there been no education before now for people in my area, for example, to "stock up" on potassium iodide pills?

Do you see where I'm going with this? Unless you are in an area where there is a REAL danger, you don't need these pills. If the available pills are all "hoarded up" buy people in a panic, and you find yourself needing potassium iodide and can't afford the jacked up prices, or there is none available, eat iodized table salt! It has potassium iodide in it, and in a "pinch" as I mentioned before, you will get some of what you need.

Also where did you come up with the amount "2 Kg"? Just curious.... Because I haven't read that particular amount anywhere. The lables I've read on the pill bottles say "daily value not established", and the pills are 32.5 mg per tablet. So what are people suppose to do, take 2 or 3 bottles of the pills to get the 2Kg you advise?

Sorry but I have my doutbs.

Guest on March 30, 2011:

My research indicates you can take about a tablespoon of table salt per day to absorb the needed potassium iodide needed.

Leah Lefler (author) from Western New York on March 30, 2011:

You would have to take over 2Kg of salt per day to get the right quantity of KI from iodized salt - that would kill you. For people near a source of radioactive contamination, they MUST take the pills - there is absolutely no way to get a sufficient quantity of iodine from salt (for radiation protection). Iodized salt is enough to prevent goiters in populations that don't have access to seafood, but it is not sufficient to protect against radiation poisoning.

RunAbstract from USA on March 30, 2011:

Naturally you would have to use more iodized salt than normal... not just what you sprinkle on food. But the fact is, iodized table salt is IODIZED with potassium iodide, and you CAN get near or the same results as taking the pills in "have to" sistuations.... using MORE salt than normal.

I saw a bottle of potassium iodide go for around $600 on ebay recently, and that is ridiculous! Especially considering how inexpensive it actually is! Cheap enough in fact that it is put into normal TABLE SALT! Which will, in a pinch, fill the thyroid up with non-radioactive iodine, (if taken in larger than usual amounts), when potassium iodide pills are not available.

I believe people should know this, so if the producers of potassium iodide pills or liquids run short, or if suppliers start gouging the public, folks are aware of simple solutions readily available.

Potassium iodide is potassium iodide, no matter if it is in a pill, a liquid, or in table salt.

Leah Lefler (author) from Western New York on March 21, 2011:

In the United States, most people who reside within 10 miles of a nuclear power plant are given potassium iodide pills to store. I hope the situation in Japan calms down very soon - children and adolescents are at the most risk from the radiation. It just breaks my heart.

Brenda Barnes from America-Broken But Still Beautiful on March 20, 2011:

This Hub is certainly interesting in light of the tragedy in Japan. I am filing it in the memory banks for future reference.

A very interesting read!

Leah Lefler (author) from Western New York on March 18, 2011:

Just to clarify,

For people exposed to radiation danger, the concentration of sodium iodide in iodized salt would not be sufficient to ward off the dangers of radioactive iodine released from a nuclear power plant meltdown. For people in a danger area, the sodium iodide tablets are necessary, but people outside the danger area shouldn't take them.

Iodized salt does prevent goiters in people who lack access to seafood or other natural iodine sources (the thyroid needs some iodine to function normally). Iodizing salt is a nutrition supplement, not an alternative to preventing disease from exposure to radiation.

RunAbstract from USA on March 18, 2011:

This is very good information, but as you mentioned, potassium iodide is in common table salt, so the same or near the same benefits can be found with using iodized table salt. And for a lot less money.

Thanks for a very good article!