A review of the TAEA proficiency test on natural and anthropogenic radionuclides activities in black tea.

A proficiency test amongst 15 Turkish laboratories with participation of 5 non-Turkish laboratories was organized to determine the 137Cs, 40K and 90Sr massic activities in black tea powder samples. The bulk material, consisting of tea produced in 2014, was mixed with contaminated tea that was withdrawn from the market after the Chernobyl accident. Nineteen laboratories reported 41 results. The evaluation of the results was based on the accuracy and precision criteria adopted by the IAEA Proficiency Testing Group and resulted in 49% acceptable results, 19% acceptable with warning and 32% were found to be not acceptable.