NEW YORK -- Potassium iodide pills have played a central role in Japan's nuclear response. And they've contributed to widespread paranoia in the United States, as people fearing exposure to radiation from thousands of miles away have snapped up the substance from drugstore shelves and online vendors.
But as a matter of U.S. emergency preparedness policy, the government's distribution of potassium iodide to people living near nuclear plants is a hazy and voluntary process that varies widely from state to state.
Although the Nuclear Regulatory Commission included potassium iodide in its emergency preparedness regulations nearly a decade ago, the decision on whether to distribute the radiation pills to the public was left up to individual states. Twenty-three of the 33 states that have people living within 10 miles of nuclear power plants have chosen to participate in the federal program.
The inconsistent standards across the country point to the difficulties in managing public perceptions of a nuclear disaster and reveal a lack of consumer education about how the pills work. State officials who have chosen not to distribute potassium iodide say they worry that residents might be lured into a false sense of security and not evacuate in the case of a disaster.
But doctors and other public health advocates have long urged for a more centralized approach on potassium iodide, which can reduce the risk of thyroid cancer for those exposed to radioactive iodine, particularly in infants and young children. Critics have long said that the federal government has shied away from requiring distribution of the pills to avoid any negative stigma attached to living near a nuclear plant.
"Everyone agrees with the need for evacuation," said Dr. Lewis Braverman, a professor at Boston University School of Medicine who coauthored a 2004 National Academy of Sciences report advocating the use of potassium iodide for anyone at risk from radioactive iodine. "But if that doesn't occur, or if it's slow, and you're worried about radioactive iodine in the atmosphere ... then I think it should be available."
Potassium iodide is available over the counter in drug stores, but not in great supply. As evidenced by the run on the substance at drugstores in the United States, the pills are often misunderstood.
If taken shortly before or after exposure to radiation, potassium iodide can be effective in reducing the risk of thyroid cancer, mostly for people under 40. But they are in no way a panacea for the effects of radiation, since exposure to other radioactive elements can lead to other illnesses, such as lung cancer.
Taking the pills effectively fills the thyroid gland with enough iodine to prevent the gland from absorbing radioactive iodine, a harmful isotope emitted from a nuclear reactor.
Nonetheless, other countries with extensive nuclear power industries, such as France, have consistent distribution of potassium iodide to households living near nuclear plants. For years, the American Thyroid Association and the American Academy of Pediatrics have pushed for greater and more consistent distribution of the pills.
Greater distribution doesn't mean greater intake, though. States that do participate in the program warn that the pills should only be taken as directed -- in case of emergency, while evacuating to a safe distance.
Following the 1979 Three Mile Island accident in Pennsylvania, a commission appointed by President Jimmy Carter recommended that the United States stockpile potassium iodide, but the Nuclear Regulatory Commission did not adopt a rule regarding the substance until 2001.
The rule now "requires that consideration be given to including potassium iodide as a protective measure for the general public that would supplement sheltering and evacuation." It applies to states that have populations within 10 miles of a nuclear plant.
At the time, the commission told states that there would only be a one-time distribution of the pills; since then the commission has told states they will continue to provide more supplies if they run out.
Individual states had to come up with a distribution plan and submit it to the Federal Emergency Management Agency for approval. Methods of distributing potassium iodide vary: some states stockpile it in case of emergency, while others make it available to the public at regular intervals.
Officials in states that have chosen not to distribute the potassium iodide to residents point out that the pills only address the thyroid gland, and not other parts of the body that could be harmed by exposure to radioactive elements. They also point out that pills could deter evacuation efforts.
"It's better for them to leave the area and get no exposure to radiation than rely on protection from one kind of radiation," said Chris Van Deusen, a spokesman for the Texas Department of State Health Services.
Other health officials said they decided not to distribute the pills because of logistical questions: how and when to hand out the pills.
"If we're telling people to get out, but they'd rather get potassium iodide first at some distribution point, it confuses our emergency plan," said Donn Moyer, a spokesman for the Washington Department of Health, which opted not to participate in the federal program.
But the inconsistencies are notable.
In Wisconsin, for example, potassium iodide is handed out in a county near two power plants but not near another one.
County officials near Wisconsin's two nuclear power plants along Lake Michigan did not want to distribute the pills. But potassium iodide is distributed in a county on the other side of the state, which is within 10 miles of a nuclear power plant in Minnesota.
Minnesota officials did opt into the federal potassium iodide program, so officials in the adjoining Wisconsin county felt it would be inconsistent if they were not also available in Wisconsin.
The Nuclear Regulatory Commission has not announced any specific policy changes since the Japan disaster, but noted that the commission is reviewing "all aspects of nuclear power plant safety and security regulations."