Strontium-90 in milk and some dairy products in the Republic of Serbia

Abstract

Radiostrontium is released to the environment during the testing and use of nuclear weapons mainly in the fifties and sixties of XX century, in addition to nuclear power plant accidents (to some extent in 1986 owing to the Chernobyl accident) and the nuclear fuel reprocessing industry. Strontium is a chemical analogue of calcium (both are earth-alkaline metals) and accordingly when entering a human or animal body, it behaves similar to calcium. A large portion of the strontium will accumulate in bone and teeth and then is included in the metabolism along with Ca, and like calcium, it transfers to milk. Since the strontium uptake by the human body from milk is an important pathway for radiostrontium incorporation, milk and dairy products are good indicators of strontium-90 (Sr-90) content in human diet. Based on the mentioned, the knowledge about Sr-90 content in milk and dairy products is of extreme importance to prevent and control contamination of the food chain. The present study was conducted in order to radiologically control for Sr-90 content in raw milk and some dairy products samples composed of representative locally purchased milk. The analyses are performed using radiochemical analytical oxalate precipitation method, whereby interfering radionuclides are removed by precipitation scavenging. Yttrium-90 (Y-90) is generated from the beta decay of Sr-90. After the ingrowth Y-90 is separated and equilibrium is established, the samples are measured by gas flow proportional counter. The results of investigation showed that Sr-90 activity concentration in many investigated samples was at a lower level than minimum detectable activity (MDA) of the method.