Between 1999 and 2002, IRSN studied the influence of 137 Cs hot spots on the contamination of alpine foodstuffs (milk, cheese, mushrooms, berries and whid game) and the dose associated with it. Measurement of samples from a “worshop area” containing hot spots revealed strong variability in the radioactivity of mushrooms (273-1165 Bq.kg-1 fresh weight) and blueberries (5-140 Bq.kg-1) fresh weight). Although these activity levels cannot be directly imputed to the hot spots, we also cannot exclude the possibility that a different harvest would yied a higher proportion of mushrooms or berries from hot spots and thus be even more raioactivity. The activity measures in large game (deer, antelopes, mouflons and boar) is low (a few Bq. Kg-1 fresh muscle weight) relative to the environmental contamination. The high activity measured in milk (1.3-6.2 Bq.L-1), among the highest in milk in France, is related to that in the grass (50 Bq.kg-1). The milk activity is only influenced by the ingestion of grass growing on hot spots (where activity careach 800 Bq.kg-1), but this may explain a part of its variability. In situ dose rate measurements showed that the contribution of '3'Cs to the amblent dose rate reaches 40 %. Nevertheless, the dose associated with spending a few hours around the hot spots is quite low (a few microsieverts). The principal exposure route for humans involves ingestion of mushrooms picked at hot spots. The dose in such a scénario can reach 10 to 100 microSv.
* Institut de Radioprotection et de Surete Nucléaire DPRE/SERNAT/LERCM,Centre d’Etudes de Cadarache, BP 3, 13115 Saint-Paul-Lez-Durance Cedex,France
** Commissariat à l ’Energie Atomique,DEN/DPC/SECR/LANIE,Centre d ’Etudes de Saclay,91191 Gif-sur-Yvette,France