Drug protects thyroid from effects of radiation exposure

Potassium iodide pills in the medicine cabinet could prove beneficial to patients, especially those living downwind of a nuclear power plant.

By Susan J. Landers, amednews staff. Jan. 21, 2002.

Washington -- With the nation still reeling from the horror of anthrax-tainted mail, another equally monstrous scenario captured the public's mind. In this one, terrorists aim fully fueled jets at nuclear power plants.

The mere thought of such a catastrophe is enough to send many people running, if not to a fallout shelter, at least to their pharmacies for potassium iodide, or KI.

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The drug, inexpensive, relatively safe and available without a prescription, has been found to prevent thyroid cancer among those exposed to the radioactive iodine that would likely be released in a nuclear accident.

Just recently the federal government announced that it was stockpiling millions of doses of potassium iodide -- just in case.

As more people become aware of KI they may well turn to their physicians for advice on whether to stock up on the medicine.

Many experts say they should.

One expert recommends having two KI pills for every family member.

"Potassium iodide is a medication of potential use and benefit to the population exposed to a nuclear accident," said Hossein Gharib, MD, president-elect of the American Assn. of Clinical Endocrinologists.

"Potassium iodide is safe, inexpensive and should be available," Dr. Gharib said

"If patients ask, I would say, 'Yes, you should get tablets for those in your home,' " said Lewis Braverman, MD, professor of medicine at Boston University. "I don't see any rationale for not doing it."

Dr. Braverman, speaking for the American Thyroid Assn., said he would suggest obtaining two tablets for each family member. Each pill provides about 24 hours of protection with dosage varying by age and weight of the individual.

Children and adolescents are the most vulnerable to exposure, while adults older than 40 would need the medication only if they were exposed to a very large dose of radiation.

Pharmacies should be able to obtain the pills, Dr. Braverman said. Potassium iodide is also available via the Internet.

A skeptical view

But not all experts are convinced that everyone should have potassium iodide at the ready. Robert Hallisey, director of the Massachusetts Dept. of Public Health's Radiation Control Program, said that providing the drug to the general public would be a mistake.

He fears that people will think the drug is a magic pill that will protect them from any and all radiation exposure. It won't.

Children and adolescents are most vulnerable to the effects of radiation exposure.

KI protects against only radioiodine, and there would be many other harmful radioactive elements released in a nuclear accident.

Hallisey also fears that people wouldn't heed evacuation orders if they have a pill that is, in reality, no panacea.

But even so, the Massachusetts Public Health Dept. is reevaluating its KI policy for the public because of the possibility of terrorist attacks, Hallisey said. The state has one nuclear power plant within its borders and two others just across state lines in New Hampshire and Vermont.

"We have written to the nuclear regulatory commission to ask them about the availability of KI, and we are looking into using it as a supplement to evacuation and sheltering," Hallisey said.

Dr. Braverman agreed that suggesting residents pop a KI pill should not be a state's first line of defense.

"The first line is to get out," said the Massachusetts resident. "But what about people piling into their cars and getting stuck on the roads?"

Before or during evacuation, the least people can do is protect their thyroid, he said.

Studies done after the Chernobyl nuclear plant accident in 1986 found that thyroid cancer rates in areas downwind of the accident site began to soar by 1990. Researchers found that children were particularly susceptible to thyroid cancer from radioactive iodine because their thyroid glands are small and tend to concentrate the harmful iodine from radioactive fallout.

To provide the best protection against inhaled radioiodines, potassium iodide should be administered before or very shortly after exposure, according to the Food and Drug Administration, although substantial protection could be provided if the pill is taken three or four hours after exposure.

The medication works by saturating the thyroid with harmless potassium iodide so it is less likely to be affected by harmful radioiodine.

In light of the new terrorist concerns, the FDA in November 2001 reissued an updated version of its guidelines "Potassium Iodide as a Thyroid Blocking Agent in Radiation Emergencies."

The guidance is directed at other federal agencies and state and local governments. However, the FDA leaves it up to the states to adopt the guidelines.

The only states with KI stockpiles are Alabama, Arizona, Maine and Tennessee. In Massachusetts, the town of Duxbury, which overlooks the Massachusetts nuclear power plant in Plymouth, voted in 2000 to purchase thousands of doses as a precaution.

Federal legislation has been proposed that would require states to stockpile the drug for its residents. A bill introduced by Rep. Ed Markey (D, Mass.) would require states to stockpile and distribute potassium iodide to all those living within 20 miles of a nuclear power plant in addition to evacuating those at risk.

Similar bills have also been introduced in Congress.

However, even if a state has a stockpile of KI, the speed with which it could be distributed poses concern. "It's a tough problem," Dr. Braverman acknowledged. He suggests distribution through the schools, fire departments, public health agencies or the Federal Emergency Management Agency.

"But the easiest way, certainly for those within a 50-mile radius of a nuclear power plant, is to have it in people's medicine cabinets," he noted.

Dr. Braverman, who lives within 50 miles of the Plymouth plant, does not have the pills in his medicine chest. But, he points out, he's over 40 and faces less of a risk from radioiodine than does a younger person.

But Edwin Lyman, PhD, scientific director of the Washington, D.C.-based Nuclear Control Institute, would advise Dr. Braverman to have the medication at hand.

"Clearly people who live within a 50-mile radius of a nuclear power plant should probably have potassium iodide in their medicine cabinets, especially if they have children," said Dr. Lyman.

Dr. Lyman also points out a political subtext to the debate. The nuclear industry has long been opposed to the stockpiling of KI, he said, not wanting to raise even the possibility of the threat of a nuclear accident.

However, he said: "As long as you understand the uses and limitations of KI, I can't think of a reason not to have it."