Examination of Medicinal Plants for Radionuclide Absorption and their Health Implications

This study examined the concentrations of 40K, 238U, and 232Th radionuclides and evaluated the possible radiological health risks to medicinal plants found in Ewu, Edo State, Nigeria, using a NaI(Tl) gamma spectrometer. The six selected medicinal plants were Mangifera indica, Dacryodes edulis, Terminalia catappa, Cymbopogon citratus, Anacardium occidentale, and Persea Americana. The results showed that the activity concentrations for 40K ranged from 146.59 ± 4.81 in Persea americana to 296.08 3.42 Bq/kg in Cymbopogon citratus, with a mean of 209.43 ± 5.14 Bq/kg; 238U ranged from 2.25 ± 0.06 to 5.57 ± 0.15 Bq/kg, with a mean of 4.73 ± 0.15 Bq/kg; and 232Th varied from 4.50 ± 0.35 to 12.07 ± 0.57 Bq/kg, with a mean of 8.00 ± 0.40 Bq/kg. The maximum and minimum activity concentrations of both 238U and 232Th were found in Mangifera indica and Cymbopogon citratus, respectively. The calculated average committed effective dose ECED was 0.130 μSv/yr and the excess lifetime cancer risk (ELCR) has a mean of 0.00913 (× 10^-3). The radiological hazard assessment of the investigated medicinal plants was well within the internationally recommended safe limits of 0.3 mSv/yr and 10^-4 for ECED and ELCR respectively. 232Th contributes 54.91% of the total ECED, while 238U contributes the least to 6.35%. 232Th exhibits a very strong, positive, and significant relationship with ECED and the ELCR, and it contributes largely to the ECED and ELCR due to ingestion of the examined herbal plant. Therefore, these medicinal plants are radiologically safe for human consumption.