Determination of radionuclide concentration in milk samples consumed in Republic of North Macedonia and population dose rate estimates

Abstract

Milk is one of the most important food products in the human diet and contains all the macronutrients, that are, proteins, carbohydrates, fat, vitamins (A, D and B groups) and trace elements, especially calcium, phosphorus, magnesium, zinc and selenium. Milk contamination is largely due to the grazing of animals on contaminated grass and drinking water. Grass is a direct source or route of radionuclides to animals and humans through the consumption of meat and milk. One of the important tasks of the veterinary activity is veterinary-sanitary supervision of the production and sale of milk and dairy products, whose main goal is the provision of biologically good milk and dairy products from healthy animals. The purpose of this study was to determine the activity concentrations of 226Ra, 232Th 40K and 137Cs in milk samples most commonly used in daily consumption in the Republic of North Macedonia and based on the results, the risk of radiation to the population can be estimated. An instrument - gamma spectrometer (Canberra Packard) with a high purity germanium detector and GENIE 2000 programme was used for measurement of the samples. On the basis of the performed tests, the main activity concentrations of 226Ra, 232Th, and 40K were 1.76 ± 0.23; 1.05 ± 1.00; 31.9 ± 5.07 (Bq·kg-1), respectively. 40K has the highest value compared to other radionuclides due to the process of transfer from soil to grass and from grass and water to milk. The activity of 137Cs is below the detection limit for all tested milk types. This shows that there is no risk of radiation to the population, i.e., the safety limits are not exceeded, which points out the insignificant threat of radiation arising from radionuclides that are naturally or artificially present in the tested milk, and that reach humans through the food chain.