Investigation of 131I in the thyroid of cattle

Samples of the thyroid of cattle were taken for the observation of 131I levels. In the course of the investigation the growth was ascertained of the specific activity of 131I in the thyroid gland following the nuclear tests carried out in China in 1973. A further increase was recorded in cattle at the nearby farmers cooperative in Klecany in November and December 1973 after a radioactivity leak of approximately 2.4 Ci 131I from the Institute of Nuclear Research in Rez. All radioiodine and added iodine are converted to elemental iodine which is extracted into the aqueous phase. From this it is precipitated into thallium iodide whose beta activity is measured using low-background counter TESLA NRB 213. The question is also discussed in detail of the usefulness of measuring the thyroid as against measuring other substances, e.g., milk. The sensitivity of the method is up to 0.09 pCi/g of thyroid gland. (Oy)