Frequently Asked Questions

1. Is potassium iodide effective in preventing the risk of thyroid cancer after a nuclear incident?

Yes, taking potassium iodide up to 48 hours before or 8 hours after exposure to radioactive iodine through inhalation or ingestion will protect the thyroid from thyroid cancer.

2. Is potassium iodide safe?

Yes, in general. Some people should not take potassium iodide, including those with pre-existing thyroid conditions and iodine allergies. The first dose should not be taken too late after exposure, or it might lead to a delay in radioactive iodine leaving the body.

3. Who should take potassium iodide when an accident occurs?

It is most important for potassium iodide to be taken by children, infants, and pregnant and lactating women. People over 40 should not take potassium iodide because there is an extremely low chance they will get thyroid cancer from radiation and they are at a high risk of having medical conditions that would be worsened by potassium iodide.

4. Is potassium iodide necessary for protection against harmful thyroid effects of radioiodine ingested through contaminated milk and other foods?

Food testing programs in place throughout the United States are more effective preventive strategies for ingestion pathways. Potassium iodide should mainly be used to protect against harms of inhalation exposure.

5. Why is potassium iodide used to reduce harmful effects of exposure to radioiodines?

It is readily available, inexpensive, stable, and has a long shelf-life if stored in packaging that prevents exposure to light and moisture.

6. What does the thyroid do?

The thyroid produces hormones that enter the bloodstream and travel throughout the body. These hormones stimulate tissues and organs throughout the body to regulate body temperature, the metabolism, chemical balance, and reproductive functions. The thyroid also helps to maintain normal function of the cardiovascular and central nervous systems.

7. Will the fuel that is transported by trucks and trains to Yucca Mountain in Nevada put citizens at risk of being exposed to radioiodine?

Spent nuclear fuel stored at nuclear power plants is free of significant radioiodine within weeks after the fuel has been removed from the reactor core. Therefore, spent nuclear fuel being transported most likely will not release radioiodine.

8. Who is ultimately responsible for distributing potassium iodide to the public?

States are responsible for protecting the public in the event of a nuclear incident. Each state must decide whether to obtain potassium iodide for distribution, how it will be distributed, and other policies regarding distribution.

9. How are radioactive iodines created?

Radioactive iodines are byproducts of the fission of uranium atoms. They can be produced during the operation of nuclear power plants and during the detonation of nuclear weapons.

10. What is Iodine-131 (¹³¹I)?

Iodine-131 (¹³¹I) is a radioactive isotope of iodine with a relatively short physical half-life of 8 days. It is used as a radioactive tracer in nuclear medicine and is found in fallout from nuclear testing. It has been demonstrated to cause thyroid cancer in humans after moderate and high doses following the Chornobyl accident.