[Dependence of transfer factors for cesium on the contamination level of feed]

The transfer factor-values feedstuff/meat so as the value of biological half life time for caesium are not constant but are depending on external and internal conditions. The most important external condition is the level of feedstuff contamination which reduces proportional the transfer factor's value of 0.5 +/- 0.1 asymptotically to 0.3 +/- 0.1. These values are then decreasing till to two thirds by the increasing part of uncontaminated feedstuff in the daily diet. The internal conditions, namely type of gastrointestinal tract, metabolic individuality and actual animal health, may cause a variability of transfer factor's values up to +/- 35% of the mean resulting from external conditions. The value of biological half life time of caesium may be considered as a constant for each respective tissue or organ in balanced conditions, but the changes of external conditions, especially the beginning of uncontaminated feeding, results in immediate gradually shortening of this half life time till to 50-30% of its original value.