As consumers buy up stocks of potassium iodide in stores, multiple physicians’ organizations and government health agencies issued statements advising U.S. residents not to take or hoard potassium iodide in response to radiation released from crippled Japanese nuclear power plants.
A joint statement from The Endocrine Society, the American Association of Clinical Endocrinologists, the American Thyroid Association, and the Society of Nuclear Medicine emphasizes that potassium iodide (KI) should not be taken unless there is a clear risk of exposure to high levels of radioactive iodine. Ingesting pills or solution of KI (a stable salt of iodine) can potentially block uptake of radioactive iodine by the thyroid gland.
There is no radiation emergency in the United States at this time, the organizations emphasized. Current estimates suggest that the United States and its territories may be exposed to radiation amounts that are a little above baseline atmospheric levels at most and that by the time any radioactive particles are blown here, levels are unlikely to be harmful to the thyroid gland or general health, the statement said.
A powerful earthquake and tsunami on March 11 led to explosions at multiple nuclear reactors in northeast Japan and releases of some radioactive materials into the atmosphere. At press time, the crisis continued to evolve as workers there struggle to contain further radiation releases and stabilize the reactors.
The U.S. Environmental Protection Agency monitors for radioactivity through a network of stations, and the four medical organizations noted that they will continue to monitor the potential health risks from the Japanese power plants and will issue more advisories if warranted.
The statement pointed out that at the worst nuclear plant accident in history, at Chernobyl in 1986, people in nearby regions were exposed to radioactive iodine mainly from eating contaminated food and milk, not atmospheric exposure. The risk for thyroid cancer was highest in pregnant women, fetuses, infants, and children.
Dr. Kenneth A. Woeber, clinical chief of endocrinology at the University of California, San Francisco, said in an interview that he agrees with the organizations’ statement. He particularly worries about pregnant women in the United States taking KI unnecessarily, because it can cross the placenta and cause fetal goiter and hypothyroidism.
"I’ve had a lot of patients call me in a panic," he said. "One patient wanted me to write a prescription" for KI. "I told her, ‘No.’ "
Consumers have cleared stocks of KI from many stores and pharmacies, according to news accounts, especially panicked parents.
In addition, KI taken unnecessarily can cause allergic reactions, skin rashes, salivary gland inflammation, hyperthyroidism, or hypothyroidism in a small percentage of people, the statement cautioned.
"People should not panic" and take KI, Dr. Woeber said. "The harm-to-benefit ratio is overwhelmingly in favor of harm" unless authorities declare a radiation emergency.
The Centers for Disease Control and Prevention (CDC) also advised against taking KI or iodine supplements in response to the power plant explosions in Japan on its Web site’s Emergency Preparedness and Response pages. The CDC added that KI does not protect other parts of the body from radioactive iodine, and does not protect the body from any radioactive elements other than iodine. No radioactive iodine has been detected so far in the United States or its territories, according to the CDC.
Both the CDC and the Food and Drug Administration (FDA) cautioned consumers especially to not take iodine supplements that have not been approved by the FDA, and to watch out for fake anti-radiation products such as dietary supplements, food items, or fraudulent drugs, devices, or vaccines. The FDA posted a Radiation Safety page at its Web site to offer information.
KI is prescribed to some patients in preparation for thyroid surgery because it makes the gland less vascular, thus making it easier for the surgeon to operate, Dr. Woeber said. KI also is used in rare instances of a patient presenting in thyroid storm. A shortage of KI supplies in stores shouldn’t be a problem, he said.
Dr. Woeber said he has no relevant conflicts of interest.