In 1982, the U.S. Food and Drug Administration approved potassium iodide to protect
thyroid glands from radioactive iodine involving accidents or fission emergencies.

In an accidental event or attack on a nuclear power plant,
or in nuclear bomb fallout,
volatile fission product radionuclides may be released.

... By saturating the body with a source of stable iodide prior to exposure,
inhaled or ingested (KI) tends to be excreted,
which prevents radioiodine uptake by the thyroid.

The protective effect of KI lasts approximately 24 hours.
For optimal prophylaxis,
KI must be dosed daily until a risk of significant exposure to radioiodine by either inhalation or ingestion no longer exists.

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