When the Cheronbyl reactor exploded some 800 miles from where I lived, throwing a fair bit of I-131 into the atmosphere, the first thing I did was paint every family member's ass with ordinary drugstore iodine, on a biophysicist's advice. His explanation for the measure: the body absorbs only limited amounts of iodine daily from all sources, and if you saturate the demand with non-radioactive iodine, it may help bypass the absorbtion of the radioactive excess. Don't know if it will work for someone who already has the radioactive variety inside the body, but that's the only measure I'm aware of, so I pass it on. If you want to give it a try, paint a net with a Q-tip rather than cover an area of the skin completely, to avoid irritation.