2 radioactivities, regulations and facts

As the average dose at the world scale released by natural radioactivity is 2.4 mSv/y and as no health hazards has ever been discovered in this range of radiation exposure, the setting of radioactivity levels, that are required in regulations as thresholds that trigger specific protection or surveillance measures, are more or less arbitrary and the gap between regulatory thresholds and biological thresholds is widening. This article presents the changes that have occurred in the setting of regulatory thresholds. The last concept is the clearance level (in the range of 10 μSv/year), below which radioactivity is considered negligible. The existence of a 10.000 factor between the clearance level and the level below which no effect has ever been detected (100 mSv/year) is a safety margin that allows a safe and reasonable dismantling of nuclear facilities. (A.C.)