Natural Radioactivity and Heavy Metals Measurement in Rice and Flour Consumed by the Inhabitants in Saudi Arabia

Abstract

The natural radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K and some heavy metals (Fe, Cd, Zn, Cu, Mn, Ni and Pb) were measured in samples of rice and flour consumed in Saudi Arabia. Gamma ray spectrometry was utilized to determine the activity concentration of the three nuclides. Heavy metals were analyzed by an inductively coupled plasma optical emission spectrophotometer (ICP-OES).The findings indicated that the average concentration of 226Ra, 228Th and 40K in the rice samples were 1.08, 1.19 and 83.08 Bq/kg, respectively. While, in the flour samples, the average concentrations were1.65, 1.61 and 171.31 Bq/kg, respectively. The ingestion doses were calculated to be 0.224 &muSv/Y for the rice and 0.471 &muSv/Y for the flour samples which are below the recommended 1mSvlimit. The concentration of heavy elements (Fe. Cd, Mn, Ni and Pb) in the rice and flour samples were below the detection limits. Whereas, the mean contents of Cu were 3.75 and 3.6mg/kg of the rice and the flour samples, respectively. The mean values of Zn in the rice and the flour samples were 19.42 mg/kg and 17.3 mg/kg, respectively. The daily intake of Cu and Zn through the rice and the flour samples were lower than the tolerable daily intakes by FAO/WHO; this indicates that there is no risk of intaking these foodstuffs by people.