Presence of natural radionuclides and toxic elements in monocalcium phosphate, complete feed and pig manure.

Naturally occurring radionuclides and toxic elements are ubiquitous in the environment and can pose a great risk to animals' health. Control of these toxic substances in animal diet is essential for animal's welfare, human nutrition risk management as well as environmental protection. Our study addresses these issues by determining a content of natural radionuclides (K, U and Ra), and toxic elements (Cd, Cr, As) in total of 108 samples: 36 monocalcium phosphate, 36 complete feed and 36 pig manure samples that were collected from 6 different commercial farms in the Republic of Serbia. In monocalcium phosphate the content of K, U and Ra ranged from 7.6-23.4 Bq kg, 13.2-1778 Bq kg and 3.6-13.5 Bq kg, respectively. In complete feed samples, K ranged from 170 to 306 Bq kg, U from minimum detectable activity (MDA) to 9.1 Bq kg, and Ra from MDA-5.5 Bq kg, while in pig manure K ranged from 146 to 531 Bq kg, U from MDA-30.1 Bq kg, and Ra from MDA-10 Bq kg. The concentrations of Cd, Cr and As in monocalcium phosphate were 0.26-14.9 mg kg, 10.3-497 mg kg, and 4.2-5.5 mg kg, respectively. In complete feed, the content of Cd, Cr and As ranged from minimum detectable concentration (MDC) - 0.78 mg kg, 0.30-7.41 mg kg, and 0.09-0.31 mg kg, respectively. In pig manure Cd, Cr and As ranged from 0.8-2.3 mg kg, 2.3-22.2 mg kg, and 0.51-5.45 mg kg, respectively. The obtained results showed that Cd concentration in monocalcium phosphate exceeded the maximum permissible legislative concentrations for phosphate additives. Monocalcium phosphate is the main source of U and Cr in complete feed, while Cd derives from other sources. For that reason excessive use of monocalcium phosphate can lead to high levels of these pollutants in complete feed and consequently in manure.