Preliminary investigation of naturally occurring radionuclides in some traditional medicinal plants used in Nigeria

The preliminary investigation of the activity concentration of Naturally Occurring Radioactive Materials (NORMs) in seven different medicinal plants; Anacardium occidentale, Azadirachta indica, Daniella oliveri, Moringa oleifera, Psidium guajava, Terminalia catappa and Vitellaria paradoxa by means of gamma spectroscopic analysis using a NaI[Tl] detector shows that the activity concentration of 40K in the medicinal plants ranges from 74.59 ± 2.19 Bq/Kg to 324.18 ± 8.69 Bq/Kg with an average of 171.72 ± 6.09 Bq/Kg. The highest activity concentration of 40K was recorded for A. indica while A. occidentale had the lowest activity concentration. 226Ra activity concentration varies from 10.79 ± 4.24 Bq/Kg to 42.47 ± 2.76 Bq/Kg with an average of 25.02 ± 3.18 Bq/Kg. The lowest activity was recorded for P. guajava while the highest activity was recorded for V. paradoxa. For the activity concentration of 232Th, it ranges from 27.76 ± 1.02 Bq/Kg to 41.05 ± 1.05 Bq/Kg, with an average of 35.09 ± 0.71 Bq/Kg. The lowest activity was recorded for V. paradoxa while the highest activity was recorded for T. catappa. The average annual committed effective doses due to ingestion of 226Ra, 232Th and 40K in the plants ranges from 0.00426 ± 0.00050 mSv/yr to 0.00686 ± 0.00044 mSv/yr with an average of 0.00538 ± 0.00035 mSv/yr, the highest value was recorded for A. occidentale while P. guajava has the lowest, the results determined for all the plants are far below the worldwide average annual committed effective dose of 0.3 mSv/yr for an individual provided in UNSCEAR 2000 report indicating that the associated radiological health risk resulting from the intake of radionuclides in the medicinal plants is insignificant. Consequently, the medicinal plants of this study are considered safe in terms of the radiological health hazards.