As fears of an accident at Europe's largest nuclear power plant grow, EU authorities have recently taken extraordinary steps to help protect Ukrainians living near the Russian-occupied Zaporizhzhia facility.
They’ve distributed more than five million potassium iodide (KI) tablets, commonly called anti-radiation pills.
And they’re not the only ones doing it.
Polish officials have done likewise in Poland, giving anti-radiation pills to fire departments in case of exposure triggered by the war in neighboring Ukraine.
The International Atomic Energy Agency, the U.N.’s nuclear watchdog, has established a presence at the facility to monitor the situation and help prevent a disaster. But the recent headlines about the vast distribution of KI pills beg the question: Do they work?
Would they thoroughly protect you against radiation in a nuclear emergency?
Dan Sowers, a certified health physicist (CHP) and the current radiation safety officer at the Defense Threat Reduction Agency, part of the U.S. Department of Defense, has an answer.
“Yes,” he says. But there are asterisks.
The answers to five pressing questions about KI and anti-radiation pills from expert CHPs explain why.
How do KI pills work? What do they protect?
KI pills, capsulated forms of stable iodine salt, can act as a backup measure to help keep the thyroid gland, the most sensitive component of the body to radioactive iodine, safe in specific radiation emergencies.
“Your thyroid absorbs radioactive iodine as readily as non-radioactive iodine,” Sowers says. “To your thyroid, they’re the same.”
But they’re not.
"In the case of radioactive iodine, when it gets into the thyroid, it collects there and starts irradiating the thyroid, possibly resulting in future deleterious health effects including thyroid cancer," Sowers says.
But if you get the right amount of potassium iodide at the right time, like you would from taking KI medication, your thyroid gland would be oversaturated before all the radioactive iodine is absorbed, reducing health-related risks.
“Your thyroid is like an iodine sponge, constantly absorbing iodine from your bloodstream to perform its normal functions,” Sowers says. “So, if you saturate your thyroid with stable iodine from a KI pill before you start inhaling or ingesting radioactive iodine, your body will naturally excrete that extra radioactive iodine with typically no negative health effect.”
With a KI pill, he adds, radioactive iodine passes from the bloodstream to the urine. Without it, it hits the bloodstream and stops at the thyroid.
When should you take KI pills?
Per the Centers for Disease Control and Prevention (CDC), KI medication should never be taken unless instructed by a public health or emergency response official or a health care provider.
When you’ve given the word, KI must be taken within 24 hours before or four hours after exposure to be most effective, the Food and Drug Administration (FDA) says.
“Those are the guidelines,” says Sowers.
Should there be an exception?
"Even if you're a day or two post-exposure, you've still got iodine—radioactive iodine, no less—in your bloodstream," he says. "In a worst-case scenario, I think we could probably find a way to advise folks to continue taking KI pills even if it's four hours post-exposure."
Who should take KI pills?
Science reveals that radioactive iodine absorbed by the thyroid can dramatically increase health risks in people of all ages. But the FDA warns that risk is greater for children and adults under 40.
“This evidence shows that it’s crucial to give children, especially newborns, potassium iodide in such an emergency,” Sowers says. The FDA also stresses that pregnant and breastfeeding women also take anti-radiation pills, which protects for about 24 hours.
While young adults—in this case, those between 18 and 40—are statistically less sensitive to the potential damage from radioactive iodine, the CDC and FDA say it’s essential they take KI medication as a precaution.
Alternatively, adults older than 40 traditionally have the lowest risk of thyroid cancer or thyroid injury after radioactive iodine exposure and, therefore, should only take KI medication if public authorities say there will be a very high amount of radioactive iodine contamination. Otherwise, the CDC says there could be adverse side effects from unnecessarily taking KI, including upset stomachs, rashes and allergic reactions.
How much KI you should take?
Often forgotten, there are two FDA-approved forms of KI medication. One is in tablet form, which governments have dispersed in record quantities. The other is a less-common oral-liquid solution.
How much KI you should take depends on one critical factor: your age.
Adults between 18 and 40 should get the highest dosage, with dosages decreasing for kids between 12 and 18 years of age, 3 and 12 years of age, 1 and 3 years of age and children under one. For precise dosage, Sowers advises visiting the CDC’s guidelines online.
And whatever you do, don’t take too much KI medication. Extra potassium iodide won’t protect you more from radioactive iodine, and too much could put you at a higher risk for side effects.
Would KI pills work in a nuclear disaster situation?
Yes, KI medication will help protect your thyroid in such a worst-case scenario, Sowers says. But it’s far from a cure-all.
To understand why, it’s essential to understand not just how KI medication works but also how nuclear reactors work.
“Reactors work by the fission, or splitting, of uranium atoms. Fission releases energy and two smaller atoms (called fission products) from one large uranium atom,” Sowers says. “Some of these atoms are likely to be iodine, most of which is radioactive.”
In an operating reactor, these fission products, including radioactive iodine, are contained within the fuel rods. “But in a major accident in which there is fuel damage and a breach of the containment building, some of these fission products will go airborne in a plume,” he says. When that happens, they’re eventually inhaled or ingested via the food chain.
“But let’s be clear: it takes a lot—and I mean, a lot—of radioactive iodine to induce a health effect,” Sowers says.
CHPs know this from following Chernobyl survivors following the infamous 1986 disaster and in medical treatment of some thyroid diseases by intentionally administering radioactive iodine in high doses.
Further, in 2011, when Americans on the west coast took KI to “protect” themselves from Fukushima fission products, their effort had no consequence minus a psychological placebo effect.
“So, yes, KI can help protect your thyroid if you’re downwind in the middle of a large reactor accident plume,” Sowers says. “But KI is not a pill to protect you against radiation or any of the other dozens of radioactive fission products also released in a plume.”
The Health Physics Society also says that KI does not keep radioactive iodine from entering the body, nor does it reverse the health effects caused by radioactive iodine once the thyroid is damaged. And its lone goal is to protect the thyroid, not other parts of the body, from radioactive iodine.
“KI isn’t an ‘anti-radiation’ pill per se, but it has its uses,” Sowers says. “Let’s just hope we don’t get to a point where lots of folks in Ukraine need to take a lot of them.”
If they do, any CHP will tell you to take your KI medication if indicated by public health officials in the appropriate dosage based on your age, while following the recommendations to get inside, stay inside and stay tuned.
*The opinions expressed by Daniel Sowers are his own personal views, not those of DoD or DTRA.