John Libbey Eurotext

Environnement, Risques & Santé

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Influence of hot spots on cesium‐137 contamination of an alpine food chain and doses associated with it Volume 2, issue 2, Mars 2003

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Authors
Institut de radioprotection et de sûreté nucléaire (IRSN), Département de protection de l‘environnement, Centre d‘études nucléaires de Cadarache, Bât 153, 13108 St‐Paul‐lez‐Durance <laurent.pourcelotirsn.fr>
  • Key words: food chain; soil pollutants, radioactive; cesium radioisotopes; food contamination, radioactive; radiation dosage.
  • Page(s) : 112-20
  • Published in: 2003

Between 1999 and 2002, IRSN studied the influence of 137Cs hot spots on the contamination of alpine foodstuffs (milk, cheese, mushrooms, berries and wild game) and the doses associated with it. Measurements of samples from a "workshop 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 yield a higher proportion of mushrooms or berries from hot spots and thus be even more radioactive. The activity measured 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 France, is related to that in the grass (50 Bq.kg ‐‐1). The milk activity is only slightly influenced by the ingestion of grass growing on hot spots (where activity can reach 800 Bq.kg ‐‐1), but this may explain a part of its variability. In situ dose rate measurements showed that the contribution of 137Cs to the ambient 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 scenario can reach 10 to 100 µSv.