French approach for the distribution of iodine tablets in the vicinity of nuclear power plants.

Abstract

In the event of an accident, isotopes of iodine including 131I can be released into the atmosphere. In 1997, as a safety measure, the French government decided to begin the distribution of stable iodine tablets in advance, directly to those living in the vicinity of the nuclear power plants, to avoid having to do so in an emergency. The tablets were previously stored by Electricite de France (EDF), which held them at the disposal of the government authorities. This year, as the existing tablets pass their use--by date, EDF has begun redistributing stable iodine within a ten-kilometer radius around its nineteen nuclear sites. We review the effectiveness of this countermeasure as well as the nature and incidence of possible side effects while measuring the duration of its action under the conditions in which it was administered. A bibliographic study of the kinetics of iodine in the human body has enabled the indications and the means of use to be determined. The effectiveness of the preventive effect and the onset of thyroid dysfunction depends on both external and individual factors: uptake of iodine from food, functional condition of the thyroid, and age. In an individual with a healthy thyroid, taking 100 mg of stable iodine immediately before exposure to radioactive iodine reduces the dose to the thyroid by at least 95%. In cases of prolonged exposure, the reduction is smaller. Therefore, if exposure lasts for a number of days, consideration needs to be given to taking stable iodine again, to maintain maximum protection. In addition to the bibliographic study, this presentation covers the impact of making iodine available and the action taken to educate the public; the attitudes of populations concerned; and the reaction of the health professionals.