I live 3,000 miles away from Los Angeles, yet I've received several phone calls in the last week from patients seeking prescriptions for potassium iodide. Even in New York City, where I practice, pharmacies are selling out of these pills.
It's all in response to the ominous reports from Japan, where a stricken nuclear power plant in Fukushima has been emitting radiation since weathering the twin assaults of a magnitude 9.0 earthquake and a devastating tsunami. U.S. Surgeon General Regina Benjamin's endorsement of the idea that the public should stock up on the pills as a "precaution" only provoked more fear.
One of my patients, a 62-year-old editor named "Kate," was insistent. She had charted the course that clouds of radiation emanating from northeastern Japan might take.
How do you know that the winds won't blow the radiation from Japan to Hawaii to California to here, she asked me, the anxiety evident in her voice. Don't you think I need to be prepared?
I did my best to fight fear with fact, explaining that the chances of a significant amount of radiation getting even as far as Hawaii were extremely close to zero. She didn't sound reassured.
I pointed out that following the Chernobyl disaster in 1986 — the granddaddy of nuclear accidents — clouds of radiation blew from the Ukraine over Europe, but there is absolutely no evidence that it increased cancer rates there as a result. That didn't seem to calm Kate's nerves either.
Nuclear radiation does contain cancer-causing chemical isotopes, including iodine-131, cesium-137, strontium-90 and plutonium-239. Though plutonium remains in the environment for several thousand years, multiple studies have shown that significant radiation exposure — some reports say as much as 1,000 millisieverts — is required to increase the cancer incidence by even 5%. For the sake of comparison, a chest X-ray exposes a patient to 0.1 millisievert of radiation.
It's all about the amount of exposure and how long you are exposed, I told Kate. You have no risk whatsoever. If you want to keep an emergency supply of water, food and your regular medications on hand in case of emergency, that makes sense. But potassium iodide doesn't.
But she was still not convinced. She had Googled "Chernobyl" and discovered that 17 million people in Poland had been given potassium iodide pills in the months following the disaster to protect their thyroids against radioactive iodine. Her informal research informed her that 6,000 Russian children had developed thyroid cancer, most of them from drinking milk that was contaminated with radioactive iodine. She said she thought of those poor children and wondered whether it could happen to her. What was the downside to keeping the pills around, just in case?
Potassium iodide pills work because they fill the thyroid gland with a safer form of iodine, thus helping prevent the uptake of any radioactive iodine that might be encountered. But the problem, I told Kate, is that if you have the pills you'll be tempted to take them — and they aren't without side effects.
Potassium iodide can interfere with the body's normal production of thyroid hormone, leading to hypothyroidism, or can provoke an already diseased thyroid gland to make too much of the hormone. The pills can also cause nausea and diarrhea, and you can develop an allergy to them, I said.
Having them in her medicine cabinet could also send her brain the erroneous message that radiation exposure could be imminent.
Kate's interest in the pills waned when she heard all of this, and I was aware that I was using one fear (of the pill's side effects) to combat another (the radiation).
People are afraid of the unknown, especially invisible dangers like radiation. Many of us, including Kate, remember the nervous days in the 1960s when we endured air raid drills and hid under our desks at school, anticipating a nuclear attack. When we hear the term "radiation," even if it is all the way across the ocean, we can't help the impulse to personalize the risk and think we could be next.
The idea of getting cancer also terrorizes us, compounding our radiation fear and sending us on frantic searches for antidotes like potassium iodide.
I completely understood where Kate was coming from, even though I was convinced she had no cause for concern. Despite feeling sympathetic, I had no intention of prescribing the pills or encouraging their use.
If I were living in the vicinity of the Fukushima plant, I might consider taking potassium iodide. But not Hawaii, not in California — and definitely not in New York.
Siegel is an associate professor of medicine and medical director of Doctor Radio at New York University Langone Medical Center.