Activity concentrations of 137Cs, 40K, and 210Pb radionuclides in selected medicinal herbs from Central Serbia and their effective dose due to ingestion

Abstract

Specific activity of ¹³⁷Cs, ⁴⁰K, and ²¹⁰Pb radionuclides in fifteen selected medicinal herbs from three locations in Central Serbia (two mountains, Kopaonik and Zlatar, and a valley, Sokobanja) was measured using two semiconductor HPGe spectrometer systems. The obtained values are in intervals (<0.3 ÷ 9.7) Bq/kg, (<0.2 ÷ 24.7) Bq/kg, and (<0.2 ÷ 5.7) Bq/kg for ¹³⁷Cs; in intervals (125 ÷ 1100) Bq/kg, (104 ÷ 872) Bq/kg, and (103 ÷ 954) Bq/kg for ⁴⁰K, and in intervals (3.6 ÷ 49.0) Bq/kg, (3.9 ÷ 57.9) Bq/kg, and (2.8 ÷ 103) Bq/kg for ²¹⁰Pb, for herbs from Kopaonik, Sokobanja and Zlatar, respectively. The highest activity measured in individual herbs was: 24.7 Bq/kg for ¹³⁷Cs (Sokobanja valley), 1100 Bq/kg for ⁴⁰K (Mt. Kopaonik) and 103 Bq/kg for ²¹⁰Pb (Mt. Zlatar). The corresponding individual annual effective doses due to ingestion calculated from the measured activity concentrations, of the radionuclides are: in intervals (<1.7 ÷ 82.9) nSv, (<1.4 ÷ 211) nSv, and (<1.1 ÷ 48.7) nSv for ¹³⁷Cs; in intervals (0.76 ÷ 4.5) μSv, (0.64 ÷ 4.4) μSv, and (0.63 ÷ 4.9) μSv for ⁴⁰K, and in intervals (1.1 ÷ 18.2) μSv, (1.3 ÷ 21.6) μSv, (0.9 ÷ 38.3) μSv for ²¹⁰Pb, respectively. The specific activity concentration values of ¹³⁷Cs and ⁴⁰K obtained for the investigated herbs are similar to the literature data, while no information was found in literature about specific activity concentration of ²¹⁰Pb. The all values obtained for individual annual effective dose due to ingestion are less than 100 μSv, which means that the daily use of 200 mL of herbal infusion during a year made from the investigated herbs does not represent a radiological risk for health. However, a high individual annual effective dose of ingestion of ²¹⁰Pb obtained for some herbs indicate that their consumption in larger amounts 2-3 cups of infusion daily over a year could make the dose to exceed the recommended level, and points to necessity for extensive investigation of ²¹⁰Pb activity concentration worldwide.

Keywords: Effective dose of ingestion; Gamma spectrometry; Medicinal herbs; Radioactivity.