Evaluation of 14C doses since the end of the 1950s in metropolitan France

The dosimetric consequences of 14 C dissemination resulting from the radioactive fall-out of atmospheric nuclear-weapons testing conducted in the 50s have been estimated. Owing to the lack of 14 C measurements in food consumed in France over the past 60 years, this evaluation is based on the standard modelling of the isotopic equilibrium: it is assumed that the specific activity ( 14 C/C) of living plants is in equilibrium with that of CO 2 in the air. It is also considered that this isotopic ratio remains constant in animals and their production. The specific activities of 14 C in the biosphere were drawn from reference publications. Since the 1950s, the effective dose for adults has risen from 12.1 µSv y -1 to a maximum of about 22.3 µSv y -1 in 1964, before falling to 12.9 µSv y -1 , which is slightly higher than the initial value. The excess dose due to atmospheric testing reached about 10 µSv y -1 in the sixties. The generation of 1940 was exposed to the highest dose: 190 µSv in 60 years due to nuclear-weapons testing, which remains low in relation to natural exposure.