Activity concentrations of 226Ra, 232Th, 40K and 137Cs radionuclides in Turkish medicinal herbs, their ingestion doses and cancer risks

Twenty-two medicinal herb samples, each representing a distinct species, were collected from Turkish markets and measured by the gamma spectrometric method. The activity concentration of Ra-226 in medicinal herbs was found in the range of minimum detectable activity (MDA) and 15.1 +/- 2.2 Bqkg(-1). The activity concentration of Th-232 ranged from MDA values to 3.5 +/- 0.8 Bqkg(-1). The activity concentration of K-40 varied between 50.0 +/- 16.8 and 1311.5 +/- 57.3 Bqkg(-1). All Cs-137 activity concentrations of medicinal herbs were found to have lower than MDA values. The bone surface dose, lower large intestine and colon doses were found to be 182.9, 18.8 and 18.7 mu Svy(-1), respectively. The highest committed effective dose originated from the annual ingestion of 1 kg medicinal herb was calculated notably low as 9.0 mu Sv. The cancer risk of ingestion of medicinal herbs was found to be small enough to be neglected. The selected Turkish medicinal herbs are considered safe for human consumption.