Fifteen days after the start of the war led by Russia in Ukraine, the nuclear risk is present in everyone’s mind. Pharmacies across Europe are being swarmed for iodine tablets, to be ready in case Russia uses atomic weapons or an accident at one of Ukraine’s many power plants .
France is no exception to the rule. Except that here, the use of iodine tablets is subject to very strict regulations: it is reserved for people who live within a radius of 20 km around a nuclear power plant.
They are invited to withdraw these tablets “in pharmacies during regular distribution campaigns [tous les deux ans, NDLR] or when they move in. They can thus dispose of it at their home, ”specifies Irsi, the Institute for Radiation Protection and Nuclear Safety.
However, there is no question of consuming these pellets at any time: “in the event of an accident, all means (television, radio, vehicles with loudspeakers, etc.) will be used to give instructions for taking iodine, under the responsibility of the prefect”.
Because taking iodine a little too early or a little too late cancels its beneficial effects.
But what is iodine used for? And how to use it well?
Stable iodine, radioactive iodine and thyroid. “Iodine is an essential trace element for the human body because it is involved in the functioning of the thyroid,” recalls the CEA (Atomic Energy Center).
In the event of a nuclear accident, radioactive iodine can be released into the air. The functioning of the thyroid gland can be affected by inhaling this contaminated air, because the thyroid “uses iodine to produce thyroid hormones, without distinguishing between radioactive iodine and stable iodine”, details the Irsi. Stable iodine is the one that is contained in the tablets distributed to people living near power stations.
Taking it at the right time will saturate the thyroid with stable iodine and prevent radioactive iodine from attaching to it, which will reduce the risk of contamination. However, stable iodine does not protect against other radioactive elements potentially released during such an accident.
When to take this iodine tablet? The Nuclear Safety Authority (ASN) indicates that “efficiency is optimal if the intake is carried out within 2 hours before the start of radioactive iodine releases; it is 50% if the catch is carried out 6 hours after the beginning of the releases.
The tablets must therefore be taken immediately when the prefect gives the instruction and only at that time”. Earlier, their effectiveness will be reduced and beyond 24 hours, their side effects are more serious than the expected benefits, adds Irsi.
Can I take stable iodine preventively?
It is unnecessary and potentially dangerous. “An excessive and regular intake of iodine can lead to thyroid dysfunctions but also certain adverse effects, in particular at the cardiac or renal level”, indicates the Health Security Agency (ANSES).
Hence the need to wait for the green light from the authorities in the event of a nuclear accident. Furthermore, it has not been demonstrated that stable iodine tablets would be effective in the event of Russia using the atomic bomb.
Is radioactive iodine always harmful? Radioactive iodine can be used in medicine, in particular to treat thyroid cancer: “it allows in particular to destroy the thyroid cells remaining after removal of the thyroid if there is a risk of relapse”, explains the CEA.
Furthermore, “in the case of hyperthyroidism resistant to drug blockade, treatment with iodine 131 [l’iode radioactif, NDLR] specifically destroys thyroid cells.