Radioactivity in monocalcium phosphate and complete feed mixtures for pigs

Abstract

Mineral additives, such as monocalcium phosphate, that are commonly used on pig farms, are obtained by processing phosphate mineral ore, and can contain high levels of 238U. Since ingestion is the main route of radioactive contamination of both animals and humans, the goal of this paper is to measure specific activity of natural and artificial radionuclides in monocalcium phosphate and complete feed mixtures for pigs. Mineral additives with high levels of natural radionuclides can contaminate complete feed mixtures making them unsuitable for use. Samples were collected from three different farms, and in total fifteen samples of monocalcium and forty five samples of complete feed mixture were measured. Samples of monocalcium phosphate show the 238U activity concentration of 13.2-2097Bq/kg. Other naturally occurring radionuclides are measured in monocalcium and the results give: 21.4-25.5 Bq/kg for 40K, 1.5 -12.1 Bq/kg for226Ra, 1.5-2.9 Bq/kg for 232Th, and 1.5-10.8 Bq/kg for 214Bi. These radionuclides are further measured in complete feed mixtures and only one sample shows elevated concentrations of 238U (3.1 Bq/kg) and 226Ra (3.5 Bq/kg). Potassium-40 is detected in all samples, with the specific activity range 208-329 Bq/kg, while other naturally occurring radionuclides and artificial radioceasium are below the detection limits.