226Ra and 228Ra activities in French foodstuffs

The activities of Ac-228 and Bi-214 in French foodstuffs acquired during the last 15 years allow one to obtain reference values of Ra-228 and Ra-226 activities which are usable to assess the dose to the French population due to the intake of these two natural radionuclides. As expected, because of similar U-238 and Th-232 activities in French soils (around 40 Bq.kg(-1)), the Ra-226/Ra-228 activity ratio in French terrestrial foodstuffs is close to 1. Most kinds of foodstuffs present similar mean activities: from 0.1 to 0.2 Bq.kg(-1) fresh for cereals, leafy vegetables, root vegetables, eggs and fishes (marine and freshwater). The activity in fruits is lower, around 0.05 Bq.kg(-1), similar to that of meat calculated on the basis of the numerous grass measurement results. The lowest activities are noticeable for milk: around 0.015 Bq.L-1. All these values are in good agreement with the data from various countries, but most often 2 to 3 times higher than the reference values proposed by UNSCEAR. This study also shows that due to the large variability of foodstuff activities reported by a large amount of data, it is not possible to distinguish the activities of samples from regions with a gap of only a factor of 2 between their soil activities.