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INTERESTING FACTS
Why do we monitor exactly cesium?
Human external exposure and a risk to inhale radioactive substances are
attributed to the early phase of a nuclear and radiological accident. In the years
following the Chornobyl nuclear accident in Ukraine, of the most long-lasting and
dangerous factors of radiation impact has remained radionuclide intake with food in
humans. For this reason, control of radioisotopes content in food becomes a
burning issue for quite a long period of time.
Among radioisotopes, which were released after the accident into the
environment, most capable of spatial distribution and transfer via biological
pathways are radioactive iodine and cesium. However, radioactive iodine tends to
decay rapidly so that its residence time coincides with the early phase of the
accident.
In this way, radiocesium further remains a leading contributor to distribution
in the environment. The natural environment may contain other types of
radioisotopes released from a damaged reactor, but in practice, say, uranium is
unlikely to reach those regions lacking such a mobile radioisotope as cesium. The
presence of cesium clearly shows that the radioactive contamination from the
reactor has reached a certain area; on the contrary, the absence of cesium in that
particular area means that other contaminants from the reactor are considered
unlikely.
Therefore, radiocesium is the so called marker of the distribution of the
radioactive contamination. In addition, cesium is readily absorbed and can be
transferred through biological chains (plants-animals-people). Keeping radiocesium
content in food under control, we can address the issue of consumption of
contaminated food, as well as detect pathways through which radioisotopes migrate
in various ecosystems and regions.
How to measure cesium isotopes specific activity in food?
Traditional approaches are based on laboratory studies that involve a
selection of individual samples from the food volume. These samples are placed in
containers and for measurements are positioned towards detectors enclosed in
protective facilities which are located in special rooms. The advantage of these
surveys is that they ensure high accuracy of a radiometric measurement of a
sample. Their main drawback is that this accuracy is provided only for an
individual sample but not for the whole batch. The extent to which this sample is
typical of the overall volume of food is a classic problem (heterogeneity of
contamination is not considered as the sample may be randomly selected either
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