Within the HBO miniseries “Chernobyl,” the Soviet nuclear physicist Ulana Khomyuk (a composite character performed by Emily Watson) realizes that there is been a large launch of radioactive materials someplace close by and instantly pops an iodine tablet. She then encourages others she encounters to do the identical. So, why that tablet? How does a easy component like iodine shield towards radiation?
The brief reply is that it would not have any direct anti-radiation results, however would possibly supply some oblique safety. Iodine would not keep off free-flying neutrons or take away radioactive mud from consuming water. It does nevertheless change how your physique behaves, in methods that may cut back the chance radioactive supplies pose. Here is how:
Below regular circumstances, your physique is pretty iodine-greedy. Your thyroid wants the chemical, and with out iodine, the thyroid cannot produce the hormones it often does. Individuals with extreme iodine deficiencies develop enlarged thyroid glands, or goiters. Very younger youngsters with iodine deficiencies may even develop mental disabilities, based on the American Thyroid Affiliation. Within the U.S. and different components of the world, iodine will get added to desk salt to stop these points. [5 Weird Things You Didn’t Know About Chernobyl]
However iodine, like all fundamental components, is available in completely different “isotopes,” or variations of the component. Each isotope of iodine has the identical variety of protons (53), however the variety of neutrons varies. In its pure state, Earth has just one isotope of iodine: iodine-127, which has 53 protons, 74 neutrons and negligible radioactivity. However as uranium atoms shatter within the core of a nuclear reactor, they break up into smaller atoms, most notably iodine-131.
The distinction between iodine-127 and iodine-131 is small, simply 4 neutrons. However iodine-131 is radioactive, firing off neutrons and quickly decaying, with a half-life of simply eight days, which means half of it would stay after that point. Your physique cannot inform the distinction between these two isotopes, although, and your thyroid gland will hungrily soak up as a lot iodine-131 because it does iodine-127. And as soon as absorbed, that iodine will sit in your physique, spewing radiation into the encircling tissue and damaging DNA. Taking a big dose of iodine, in principle, will sate your physique’s starvation for the substance and forestall you from absorbing the iodine-131 as soon as it arrives.
It is best to behave rapidly although. Iodine-131 is “extremely cell” in its surroundings, Kathryn Huff, a nuclear reactor engineer and College of Illinois at Urbana-Champaign professor, informed Reside Science for a earlier article. The substance enters the water, the place crops choose it up and cross it on to animals. As soon as the radioactive iodine has been launched, it’s totally tough to eliminate till it decays away. [Infographic: Chernobyl Nuclear Disaster 25 Years Later]
Nuclear accidents are nonetheless (thankfully) uncommon sufficient that there have not been very conclusive research on the outcomes of radioactive iodine exposures. However after Chernobyl, essentially the most vital launch of radioactive iodine ever, there was a spike in thyroid most cancers in youngsters within the affected space.
In line with a paper revealed in April 2000 within the journal Critiques in Endocrine and Metabolic Issues, thyroid most cancers charges throughout Ukraine in youngsters below age 15 spiked from lower than 1 in 1 million to three per 1 million. In Belarus, they spiked to 30 per 1 million. And in Gomel Oblast in Belarus, one of many worst-hit areas, thyroid most cancers charges in youngsters spiked to 100 per 1 million. (Chernobyl was simply 12 miles from the Belarus border.) Elevated most cancers charges appeared simply 4 years after the accident, and youngsters born after the explosion developed thyroid most cancers at regular charges.
It is unclear, the authors wrote, to what diploma iodine tablets saved lives. Potassium iodide was distributed after the accident, the authors famous, however that effort “was not begun till a number of days after the accident, and its use was very erratic.”
Individuals residing within the space might have additionally been unusually inclined to poisoning by way of radioactive iodine, the researchers wrote.
“The gentle iodine deficiency within the area surrounding Chernobyl may … have affected the radiation dose,” they wrote, “by rising the quantity of iodine collected and rising the dimensions of the gland through which it was deposited, and it may additionally alter the radiation impact itself.”
Whereas it could stay unclear simply what number of lives iodine tablets can save after a nuclear catastrophe, it is nonetheless commonplace apply within the U.S. to distribute the tablets to folks residing close to a nuclear plant. Within the occasion of an emergency, based on handbooks distributed by the U.S. Nuclear Regulatory Fee, security officers will instruct folks within the affected space to take the tablets.
Initially revealed on Reside Science.