|Evolution of the activity of caesium 137 in the human body|
The activity of caesium 137 in the human body has been measured near the Mol laboratory in Northern Belgium for more than half a century. Despite the laboratory large distance from nuclear tests bomb sites and Chernobyl, the peaks of activity due to these tests and the Chernobyl accident (four times weaker) can be seen. In these two cases, the decay of caesium 137 in the human body takes place much more quickly than the natural decay, which has a half-life of 30 years. Though caesium is absorbed slowly by the soil, the rapid decay of its activity in the human body means that no soil decontamination (using, for instance, Prussian blue), is needed in Belgium.