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

The dosimetric consequences of 14C dissemination resulting from the radioactive fall-out of atmospheric nuclear-weapons testing conducted in the 50s have been estimated. Owing to the lack of 14C 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 (14C/C) of living plants is in equilibrium with that of CO2 in the air. It is also considered that this isotopic ratio remains constant in animals and their production. The specific activities of 14C 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. © 2007 EDP Sciences