Iodine Salt to Treat Radiation?

Fig. 1: Next, movie cover (derricklferguson)

Over winter break I watched the movie Next starring Nicolas Cage with my dad. In the movie, the FBI was able to link a dead woman knifed in her room to a Russian nuclear attack plan because of a few potassium iodide (KI) pills found at the crime scene. The star FBI policewoman (who is also President Coin from the Hunger Games movies!) was quick in realizing that the only reason someone would take potassium iodide pills was to combat radiation poisoning. Before this movie, I had never heard of KI being used for this purpose, and expectedly I was skeptical. Before you judge me, imagine if someone had told you that a sugar pill could prevent you from dying of stomach cancer. That is the same magnitude of ridiculousness that I felt the whole KI pill thing had to be.

But, I was wrong of course. KI supplements are an established treatment for preventing thyroid cancer, one of the biggest health impacts observed after the Chernobyl meltdown [1]. So how is it that something so simple as a salt pill, because that’s what it is, can prevent one of the most odious conditions of modern times caused by a technology that took humans thousands of years to create? Turns out it’s by inhibition [2]. KI pills for thyroid cancer prevention aren’t made up of just any iodine; they are made of the ¹²⁷I isotope, which is iodine’s only stable form [3]. Ingested iodine is taken up by the thyroid gland, and if the iodine is of a radioactive isotope the subsequently produced radiation can cause thyroid cancer. KI pills work by dumping stable ¹²⁷I into the person’s blood stream, flooding the thyroid and reducing uptake of other radioactive iodine isotopes. KI pills only work in preventing thyroid cancer caused by radioactive iodine exposure, however, not other conditions caused by general radiation exposure.

Fig. 2: ²³⁵U fission product properties (Hochel, R. C.)

So, a few other questions obviously arise from this talk of iodide pills, one of which being where do the radioactive iodine isotopes come from in the context of nuclear fission? Fission of heavy atoms results in atoms of lighter weight and free neutrons that propagate the nuclear fission reaction. Some of the fission products of ²³⁵U are various iodine isotopes, including ¹³⁵I (6.33% yield), ¹³¹I (2.83% yield) and ¹²⁹I (0.9% yield) [4]. These are clearly not the main fission products of ²³⁵U, but they can still accumulate in contaminated environments, especially where large-scale nuclear fission reactions were involved such as nuclear meltdowns and atomic bomb testing sites. Another question to answer is how do the radioactive isotopes end up being ingested by people in contaminated regions? Scientists at Dartmouth, New Hampshire were able to measure increases in ¹³⁵I concentration, an indicator also of the presence of undetectable ¹²⁹I, on land but especially in local streams a year after the 2011 Fukushima meltdown in Japan [5]. They cited the increase as due to nuclear fallout from the Fukushima incident that blew across the continent and deposited itself in groundwater sources. This implies that the radioactive iodine isotopes can be both airborne and waterborne. If everything is coated in radioactive iodine, ingestion is believably imminent. To bring us full circle, there was also a run on KI pills in 2011 on the American West Coast due to fears of radioactive iodine finding its way into homes and food supplies there as well [6]. It’s funny how analyzing a simple movie premise can take us all the way to a not-so-late nuclear disaster.

Yesterday was the first day of classes, and soon enough school will be back in full swing. I've based my schedule this semester off of a google calendar with the idea that better organization will make hectic school life just a bit easier, so we'll see how that goes. My course load is two materials science classes, one materials science lab, orgo 2 and an anthropology class on modern culture. I'm hopeful that this semester will go better than last, and I'll keep you guys updated on what goes on. If you like this article or have ideas for another, be sure to leave me a comment below. Thanks for reading!