"In nearly a third of the states with nuclear power plants, nearby residents do not have the protection of federally-supplied potassium iodide pills for treatment in the event of a radiation crisis like that in Japan.
Nine states — Arkansas, Georgia, Iowa, Kansas, Louisiana, Missouri, Nebraska, Texas, and Washington — do not participate in the federal program administered by the U.S. Nuclear Regulatory Commission, according to NRC records and a survey by the Center.
Only one Wisconsin county participates in the NRC program. Illinois has not joined the federal effort either but organized its own distribution of iodine, said a health department spokesperson there.
Potassium iodide tablets, known as KI, are non-prescription iodine pills. In normal times, iodine — a natural substance — is stored in the human thyroid gland. During a nuclear accident, dangerous amounts of radioactive iodine can be released into the air and accumulate in the thyroid. The KI pills are used to fill the thyroid with safe iodine, reducing the risk of cancer and other diseases."
John Aloysius Farrell and Laurel Adams report for the Center for Public Integrity March 16, 2011.
"Japan Crisis Spikes Demand For Radiation Pills" (AP) 
"U.S. To Review Drug Supply After Japan Reactor Breach" (Reuters)