Study of the specific concentrations of ⁴⁰K and other radionuclides in the most consumed teas in Brazil

Tea is widely consumed worldwide and it is a drink prepared by infusing with parts of plants such as leaves, flowers and roots, usually prepared with hot water, and each variety acquires a defined flavor according to the processing used. This work presents an investigation about the specific concentration of ⁴⁰K in 16 tea samples utilized by Brazilian population and the effective dose associated. The tea samples were dried for six hours in an oven at 60°C and placed in 200 ml volume polyethylene pots of low radioactive background, weighed with a scale model Gehaka BG 4000 and sealed to achieve the secular radioactive equilibrium condition. The teas samples were measured using gamma spectroscopy technique with a high-purity germanium (HPGe) detector, a non-destructive nuclear method and with the LabSOCS software for the calculation of the efficiency curve. The counting time used for sample spectrum acquisition was 30000 seconds. The specific concentration values of potassium 40 ranged from 184 ± 56 Bq/kg Lemon Grass (Cymbopogon citrates) to 1087 ± 40 Bq/kg Burdock (Arctium lappa), Effective doses ranged from 1.1408 μSv/y by 6.7394 μSv/y. The values presented in this study were below the annual average for effective dose for ingestion for adults. (author)