How Potassium Iodide Protects You From Radiation Exposure

The radiation leak in Japan has sparked panic buying of potassium iodide tablets which are believed to be able to prevent radiation exposure. What is potassium iodide and how it works?

Potassium iodide (KI) is a salt of stable (non-radioactive) iodine that can help block radioactive iodine from being absorbed by the thyroid gland, thus protecting this gland from radiation injury.

What is Radioactive Iodine?

Radioactive iodine, or also known as Iodine-131, is a common byproduct of nuclear fission and is a pollutant in nuclear disasters.

So, when a nuclear accident happens, radioactive iodine can be released into the air and it also can contaminate the local food or water supply. When these materials get into the body through breathing, eating, or drinking, we can become contaminated.

If we become contaminated, the thyroid gland quickly absorb this radioactive iodine and it then damages the thyroid. When left untreated, this buildup of radioactive iodine can lead to thyroid cancer.

How do Potassium Iodide Tablets Work?

Generally, the thyroid gland can not distinguish between stable iodine and radioactive iodine. When a person takes KI, the thyroid gland becomes full and will be unable to absorb any more iodine – either stable or radioactive – for the next 24 hours.

Nonetheless, Iodine tablets can only protect the thyroid from radioactive iodine, and no other parts of the body. And, if the nuclear radiation does not contain radioactive iodine, then iodine tablets will have no effect.

It’s important to note that potassium iodide may not provide 100% protection against the thyroid-harming effects of radioactive iodine. Potassium iodide’s effectiveness depends on several factors, including:

  • The amount of radioactive iodine a person is exposed to.
  • The length of time that passes between radiation exposure and the consumption of potassium iodide.
  • How fast non-radioactive iodine is absorbed into the blood.

What About Iodized Table Salt?

While iodized table salt does contain enough iodine to maintain a healthy thyroid under normal conditions, but it does not contain enough iodine necessary to block radioactive iodine from being absorbed. So, table salt should not be used as a substitute for iodine tablets.

Who is at Risk?

  • Infants and children under 18-years-old are highly sensitive to the potentially harmful effects of radioactive iodine.
  • People who already have thyroid problems are also at a higher risk of injury.
  • Adults over 40 years of age have the lowest risk of developing thyroid cancer or injury after contamination and have a greater chance of experiencing an allergic reaction. They should not take iodine tablets unless a very large does of radioactive iodine is expected and they are told to do so.

What is the Recommended Dose of Potassium Iodide?

The Canadian Nuclear Safety Commission (CNSC) provides the following table of doses for individuals, depending on their age and whether or not they are pregnant.

IndividualsDose
Infants (under 1 month)¼ tablet dissolved in fluids (1 single dose only)
Children (1 month – 3 years)½ tablet daily crushed in food or fluids
Children (3 – 18 years)1 tablet every 24 hours
Adults (19 years or above)2 tablets every 24 hours
Pregnant or breastfeeding women2 tablets (1 single dose only)

What are the Side Effects of Potassium Iodide?

For people who have normal thyroid function, radioactive iodine is considered safe and should not have any major health issues if taken in proper doses.

Taking a higher dose than is recommended can result in adverse health effects and can even be fatal. Some side effects of potassium iodide include gastrointestinal upset, rashes, irregular heartbeat, and inflammation of the salivary gland.

People with thyroid disorders or are allergic to iodine should consult a doctor or nurse prior to taking potassium iodide.

Where Can I Get Potassium Iodide Tablets?

Potassium iodide is available without prescription. Make sure to get the KI brands that have been approved by the FDA.

You should only take potassium iodide on the advice of public health or emergency management officials. More detailed information on potassium iodide can be found at the FDA Website.

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