Survey on the presence of ⁹⁰Sr in milk samples by a validated ultra low level liquid scintillation counting (LSC) method

National Reference Center for the Detection of Radioactivity in Feed and Foodstuff, Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Italy

^a izsfgchimica@tiscali.it

Abstract

⁹⁰Sr is one of the most biologically hazardous radionuclides produced in nuclear fission processes and decays emitting high-energy beta particles turning ⁹⁰Y. ⁹⁰Sr is transferred from soil-plant to cow’s milk and then to humans if it is introduced into the environment. Radiostrontium is chemically similar to calcium entering the human body through several food chains and depositing in bone and blood-forming tissue (bone marrow). Among main foodstuffs assumed in human diet, milk is considered of special interest for radiostrontium determination, especially in emergency situations, because the consumption of contaminated milk is the main source of internal radiation exposure, particularly for infants. In this work an analytical method for the determination of radiostrontium in milk was developed and validated in order to determine low activity levels by liquid scintillation counting (LSC) after achieving ⁹⁰Y secular equilibrium condition. The analytical procedure was applied both in surveillance and routine programmes to detect radiocontamination in cow’s, goat and sheep milk samples.