Evaluation of Primordial Radionuclides in Ocimum gratissimum   and health Risk to the Consumers at Ewekoro Southwest of Nigeria

Primordial radionuclides are transported in to the plants through the leaves and roots. Medicinal plants are widely used in Africa for prevention and treatment of diseases. Ocimum Gratissimum is medicinal plant that is so used in southwest of Nigeria due to its multifunctional traditional medicinal health uses and as spice in cooking. The research is to determine the radiological health risk of these primordial radionuclides to the consumers of Ocimum Gratissimum in the study area. Fresh leaves of the medicinal plant were plucked from ten (10) different locations at Ewekoro where mining of limestone had been taking place in Ogun State, southwest of Nigeria, been the part of the plant that was commonly used. The concentrations of ⁴⁰K, ²³⁸U and ²³²Th in the fresh leaves were determined using gamma spectrometry method, and average annual committed effective dose to the adult consumers was determined. No artificial radionuclide was detected. The highest annual committed effective doses of ⁴⁰K, ²³⁸U and ²³²Th to the consumers of Ocimum Gratissimum were obtained to be 0.00133mSvy^-1, 0.00147mSvy^-1 and 0.00336mSvy^-1 respectively. The highest excess lifetime cancer risk of ⁴⁰K, ²³⁸U and ²³²Th to the consumers were calculated to be 0.0211 x 10^-3, 0.0136 x 10^-3 and 0.1434 x 10^-3 respectively. The average annual committed effective dose and average excess lifetime cancer risk of the radionuclides to the consumers were calculated to be 0.0109mSvy^-1 and 0.0379 x 10^-3 respectively. The values were below the limits of 0.3mSvy^-1 and 0.29 x 10^-3 respectively, recommended globally. The consumers of the medicinal plant do not have significant radiological health risk. Furthermore, the results obtained can serve as reference data for future studies in the study area and its environs.