Adults older than 40 years should not take KI (potassium iodide) unless public health or emergency management officials say that contamination with a very large dose of radioactive iodine is expected.
Adults older than 40 years have the lowest chance of developing thyroid cancer or thyroid injury after contamination with radioactive iodine.
Adults older than 40 are more likely to have allergic reactions to or adverse effects from KI.
So basically, I dont have a great need for it myself. Might be more useful for others in the family.