Beta Emitter Radionuclides (90Sr) Contamination in Animal Feed: Validation and Application of a Radiochemical Method by Ultra Low Level Liquid Scintillation Counting

90Sr is considered as a dangerous contaminant of agri-food supply chains due to its chemical affinity with Calcium, which makes its absorption in bones easy. 90Sr accumulation in raw materials and then in final products is particularly significant in relationship to its ability to transfer into animal source products. The radionuclides transfer (137Cs and 90Sr) from environment to forages and then to products of animal origin (milk, cow and pork meats) was studied and evaluated in different studies, which were carried out in contaminated areas, from Chernobyl disaster until today. In the present work, the development and validation of a radiochemical method for the detection of 90Sr in different types of animal feed, and the application of this technique for routinely control activities, are presented. Liquid scintillation counting was the employed analytical technique, since it is able to determine very low activity concentrations of 90Sr (<0.01 Bq Kg-1). All samples analysed showed a 90Sr contamination much higher than method detection limit (0.008 Bq kg-1). In particular, the highest mean activity concentration was registered in hay samples (2.93 Bq kg-1), followed by silage samples (2.07 Bq kg-1) and animal feeds (0.77 Bq kg-1). In fact, all samples were characterized by 90Sr activity concentrations much lower than reference limits. This notwithstanding, the necessity to monitor these levels was confirmed, especially considering that 90Sr is a possible carcinogen for human.