Since the nuclear disaster at the Fukushima Daiichi complex in 2011, IRSN has conducted research as part of the PRIODAC (*) program to examine procedures for administering stable iodine to people in the event of repeated or prolonged radioactive releases. The program, which aims to set forth guidelines to be used by the authorities in charge of protecting the population, has been extended for three more years.

In the event of a nuclear accident leading to the release of radioactive iodine into the environment, stable potassium iodide (KI) can be taken to prevent the absorption of radioactive iodine by saturating the thyroid, thus reducing the risk of developing thyroid cancer in the long term.

The possibility that accident situations will generate repeated or prolonged radioactive releases, as was observed during the accident at Fukushima Daiichi, raises many questions. Such questions pertain to the conditions in which stable iodine should be taken, side effects, the effects of repeated administration, and frequency of administration.

In 2014, IRSN launched the PRIODAC research program. The first phase enabled IRSN to acquire objective scientific knowledge in response to questions raised by an application to extend the marketing authorization in France to make KI available for repeated doses indicated for adults and children over the age of 12. This phase concluded that a 130 mg dose taken once a day for seven days effectively saturates the thyroid with no notable toxicity (5). The PRIODAC program will now run for an additional three years in order to define the parameters of repeated prophylaxis for the most sensitive segments of the population, namely pregnant women and young children.

(*) Repeated stable iodine prophylaxis in accident situations, a publicly-funded program launched in March 2014 for an initial five-year period.