A study on some stable elements and radionuclides in human milk

The behaviour of radioactive Sr was studied together with that of Ca, and the behaviour of radioactive Cs with that of K, as Ca and K are considered reference standards in studying radionuclide transfers from one compartment of the environment or of the human body to another. Radioactive Cs and K were determined by gamma spectrometry, whereas radioactive Sr was first separated via ion exchange resin and then beta measured. Ca, K and Sr measurements were carried out by Inductively Coupled Plasma Atomic Emission Spectrometry. 90Sr/Ca and 90Sr/Sr ratios were determined in some tens of human milk samples from two different Italian zones and different periods. The mean values of 90Sr/Ca were found to be 46 ± 35 and 39 ± 25mBq/g, whereas those of 90Sr/Sr 200±170 and 191±96Bq/g. K and 40K concentrations were measured in some human milk samples and for comparison in some cow and sheep milk samples. In all the three cases the 40K-to-K ratio (28-36Bq/g) showed to be in good agreement with the isotopic ratio in natural K (0/0118%). (author) 24 refs.; 4 figs.; 1 tab