Validation of the ICRP Model for Caesium Intake by Lactating Mothers with Italian Data After the Chernobyl Fallout

In the aftermath of the Chernobyl nuclear power plant accident, a research group of the Italian National Institute of Health (Istituto Superiore di Sanità) carried out two research programmes on maternal milk. One concerned the transfer of caesium radionuclides from the diet to breast milk. In the other, the activity concentrations of (137)Cs were also determined in urine and placenta. The first study estimated the mothers' average (137)Cs dietary intake, in the second study the intake was evaluated individually for each subject. In 2004, the International Commission on Radiological Protection published modified systemic biokinetic models which also account for transfer to breast milk. The model for caesium radionuclides was implemented and tested by the authors with the experimental data described above. A good agreement was obtained between measured data and model simulations of (137)Cs activity concentration in human milk. The model, however, tends to systematically overestimate (137)Cs activity concentration in urine, in which case the agreement is to be considered satisfactory in terms of order of magnitude.