The Truth About Potassium Iodide

originally posted Mar 2011

Fact-checking stories about radiation sickness and the potassium iodide prophylactic.

Since the March 11 earthquake in Japan and the subsequent failures of nuclear reactors at the Fukushima Daiichi power plant, there has been an impenetrable cyclone of news coverage about the effects of the reactor failures, including stories of a radiation plume billowing across the Pacific Ocean and into the United States. The Guardian reports that reserves of potassium iodide are low in the Western US, depleted by fears of contamination from Japanese fallout. Potassium iodide is often included in survival kits for its ability to prevent thyroid cancer in case of airborne radioactive iodine, a common byproduct of a large-scale radiation leak.

The media coverage to the upsurge in potassium iodide sales has been largely negative, with two major emerging complaints against potassium iodide buyers. The first is that they are running the risk of major side effects by taking the compound in doses recommended for cancer prevention, and the second is that the pills are in such limited supply that buying them depletes the reserves for those in Japan who may need them. (You can find these two opinions are laid out very well in this article from Boing Boing.)

Digging a little deeper, though, we find that a number of factors appear to invalidate these claims. Let’s look at them one by one.

First, that those who take potassium iodide at levels effective for the prevention of cancer run the risk of serious complications. The major problem here is allergic reactions, which for this compound are linked with shellfish allergies. So, while the pills could have serious effects for those who are allergic, less than 2% of Americans have shellfish allergies.

There are some much worse effects that can occur due to constant excessive ingestion of potassium iodide, but that doesn’t seem to be the issue here. The prophylactic dose is lower (100 vs. 150 mg) than the dosage that has been implicated in the worst of these complications: neck swelling, lack of appetite, lethargy, vomiting, and irregular heartbeat. And even that high dosage, these symptoms are only considered possible side effects. Much less scary than your average pharmaceutical TV ad.

As far as there not being enough potassium iodide to go around, there is a certain amount of truth to that claim: the three major American suppliers of potassium iodide are out of pills (due to have them again in mid-April). Indian distributors, however, are not at all difficult to find—a quick Google search unearths a number of them. Certainly there are Russian and European distributors as well, not as heavily depleted by the scare, as they are predicted to receive an even smaller dosage of Fukushima radiation, even later.

In sum, the side effects from anti-radiation pills are largely overblown, and the the shortage is mostly bogus.

Lost in this particular debate is the fact that levels levels of radiation that have reached the United States are small enough that EPA monitoring stations are not consistently able to find an increase in radioactive particles. So go ahead and take your potassium idodine if it makes you feel better. Or your sugar pills, for that matter. Because at this point, what we are talking about is a placebo cure for a non-existent illness.