Iodine for possible radiation posining

Japan has several power plants in critical condition, three which are pretty close to melt down. Radiation will devastate, unfortunately, large areas of farming communities in Japan, and the weather patterns will push the radiation from Japan through Hawaii and toward Western parts of the U.S. My concern is the radiation might reach California. Is there one iodine better than another for situations like this.

I meant exposure not poising. Don't want to alarm anyone at this point.