Why iodine pills are not a silver bullet to protect against nuclear radiation

As Russia continues to raise the spectre of nuclear war in its threats against the West over Ukraine, European countries are updating their guidelines for what citizens should do if the unthinkable happens.
Russia this week officially updated its nuclear doctrine to declare that any aggression against Russia supported by a nuclear state would be considered a joint attack, lowering the bar for use of nuclear weapons. Since Russia’s 2022 invasion of Ukraine there have also been fears of a nuclear accident, particularly regarding the Zaporizhzhia power plant in the south of the country, which is under Russian occupation.
Western politicians and intelligence chiefs have been at pains to emphasise that there is no evidence Vladimir Putin is preparing to use nuclear weapons and that Russia’s habitual threats are merely a bluff aimed at deterring the West from providing further military support to Ukraine.
However, countries near the Russian border are taking no chances, and some recently updated their advice to citizens in the event of a crisis – nuclear or otherwise.
Sweden, Norway, Denmark and Finland updated guidance telling citizens to ensure they have enough long-life food, water and medicine as well as a back-up power supply.
Iodine tablets are also among emergency supplies that citizens are advised to have at home in preparation for a crisis.
Last month Finland recommended that households buy a single dose in case of a nuclear emergency amid fears that the war in Ukraine could spiral, pharmacies began to run low on the pills.
In the event of a nuclear catastrophe, taking iodine can help to protect against some types of radiation exposure.
During a such an event, radioactive iodine can be released into the environment. If absorbed into the body – whether through inhalation or through consuming contaminated food or water – radioactive iodine can accumulate in the thyroid gland in the neck and can cause thyroid cancer to develop. Children, young people and breastfeeding women are particularly at risk.
Taking iodine tablets can help to protect against this through iodine thyroid blocking. Potassium iodide (KI) tablets – a specific type of iodine – must be taken before or at the start of exposure to radioactive iodine. This works by saturating the thyroid with stable (non-radioactive) iodine, preventing the thyroid taking in any radioactive iodine.
Iodine tablets, which are commonly taken for iodine deficiency, and are fairly cheap and accessible. However, the pills are not recommended for people aged over 40 and they should not be taken ahead of time as a preventative measure, according to the World Health Organisation.
It should be noted that iodine is not a silver bullet and cannot protect against all kinds of radiation, only the risk of internal exposure to radioactive iodine.
Radioactive iodine can be released into the air in a nuclear event and come into contact with a person’s skin, which iodine tablets would do nothing to prevent. External radioactive iodine must be removed by washing the skin with warm water and soap.
Furthermore, in the event of a nuclear explosion, many different kinds of radiation and radioactive material that can harm humans would be released, such as electromagnetic rays and other particles.
These types of radiation in the environment are more difficult to protect against, and the best advice is for people to find shelter inside, preferably in a basement or in the middle of the building, away from closed doors and windows to reduce exposure to radiation.