Activity concentrations of 238U, 232Th, and 40K radionuclides in some south African medicinal herbs and their effective ingestion doses

Measurements of 238U, 232Th, and 40K activity concentrations in some commonly used medicinal plant parts have been performed for radiation hazard assessment and as baseline data for health risk monitoring in South Africa and other countries. The mean activity of 238U, 232Th, and 40K was found to be 43.3 Bqkg-1, 33.7 Bqkg-1, and 180 Bqkg-1 in Sclerocarya birrea; 85.0 Bqkg-1, 75.3 Bqkg-1, and 316.7 Bqkg-1 in Cymbopogon citratus; 47.3 Bqkg-1, 37.0 Bqkg-1, and 773.3 Bqkg-1 in Neorautanenia ficifolia; 25.7 Bqkg-1, 30.0 Bqkg-1, and 510 Bqkg-1 in Kigelia africana, respectively. The estimated annual effective dose due to ingestion ranged from 0.013 mSv (Kigelia africana) to 0.032 mSv (Cymbopogon citratus), well within recommended limits for the members of the public. Although the values revealed no hazards from a radiological point of view, it represents a valuable database for regulatory functions.