I dug through my First Aid Kit and found my Potassium Iodide
In a radiation emergency it is good to keep some Potassium Iodide on hand to protect against thyroid cancer from radiation. It won't protect against much else except perhaps some toxic heavy metal contamination but you never can tell when a potential radiation threat materializes. I keep two vials of Potassium Iodide solution with eye droppers (~20 mg/drop). To block thyroid gland to prevent uptake of radioactive iodine contaminating food and water, take 4 drops of a saturated solution daily. (Fill a brown dropper bottle about 60% full with crystals, then add water until bottle is 90% full. Shake. Check to be sure that some crystals remain out of solution. See Nuclear War Survival Skills p. 114.)