Caesium 137 is a radionuclide of exclusively anthropogenic1 origin, which was released into the environment in very large quantities as a result of accidents (accident at the Mayak Soviet nuclear site during the 1950s2, the reactor No. 4 explosion at Chernobyl3 in 1986 and the source accident in Goiania4 in 1987) or aerial nuclear tests on the Kazakhstan plains and in south pacific.
Given its high solubility, this radionuclide difuses into the geosphere and biosphere and is detected in food chains. Moreover, given the long radioactive period of caesium 137 (30.2 years) and its elevated clearance time5 (10 to 25 years depending on the type of soil), this radionuclide is the main source of long-term exposure for the populations living in contaminated regions, either by external irradiation or by ingestion. Furthermore, several studies show a correlation between the caesium 137 whole body activity and the quantity ingested (Handl et al., 2003, Takatsuji et al., 2000), which in turn depends on the level of contamination in the area considered. This type of exposure situation by chronic ingestion of caesium 137 could therefore lead to the onset of biological effects in exposed populations.