Hi Ellacraig,
Iodium is often incorporated in Salts (Here in Europe)
Next time you go grocery shopping,
you should check out the different kinds of Salts they sell.
Also bread is a good source, since bakers often add Iodium to the bread.
A Iodium surplus from food is well compensated by the body,
so make sure you eat enough, rather then too little
Also nuclear disasters spread 3 common radioactive elements
Iodium, caesium and strontium.
Only Iodium can be stored in the thyroid.
by taking iodium pills, you can make sure this stock only consist of 'good iodium'
But notice that this is only 1 out of 3 element that spread from such a disaster
Iodium is also the one that has the shortest half-life (8 days) out of the three
Which means that after eight days, only half of the initial amount remains, and so on.
By now, you probably do not have any radioactive iodium present in your thyroids.
The other two radioactive elements have longer 'life spans' but do not stock in any particular organ
So there are no preventive measures you can take here. Just avoid radiation?
Hope this helped a bit to soothe your worry!