Question

After the Chernobyl accident, people living close to the nuclear reactor site were urged to take large amounts of potassium iodide as a safety precaution. What is the chemical basis for this action?

Short answer

Taking potassium iodide in the event of a nuclear accident may protect against thyroid cancer by filling the thyroid's iodine receptors, preventing any subsequently encountered radioactive iodine from being absorbed.

Step-by-step solution

Understanding the role of iodine in the human body

The thyroid gland in the human body absorbs iodine from the food we eat. This iodine is used to make thyroid hormones that regulate the body's metabolism and other important processes.

Realizing the danger of radioactive iodine

In the event of a nuclear accident, radioactive iodine could be released. If this radioactive iodine is absorbed by the bodies of people in close proximity, it could lead to radiation sickness or thyroid cancer.

Understanding the role of potassium iodide

Potassium iodide (KI) can be used to protect the body from radioactive iodine. The non-radioactive iodine in KI fills up iodine receptors in the thyroid, ensuring that if any radioactive iodine is subsequently encountered, it cannot be absorbed.

Grasping the timing

The important caveat here is that KI needs to be taken before or immediately after exposure to radiation for it to have a protective effect - it is not a cure if radioactive iodine has already been absorbed.