Is iodine bad for you if you have not been exposed to nuclear radiation?

I was listening to a radio show the other morning where the two hosts called every vitamin shop in town looking for Iodine pills. Every store was sold out, due to the supposed nuclear cloud headed towards the United States. After hearing this, i heard from someone else that iodine can be very damaging to the body if the person taking it has not been exposed to nuclear radiation. I understand that every person needs a certain amount of iodine to function and live properly, but if someone takes too much, (for example, people are currently taking excessive amounts because they fear the nuclear cloud coming from Japan) is it true that it can damage your organs and body?