The natural radionuclide contents in some medicinal plants commonly found around oil and gas facilities in Ughelli and nearby communities have been investigated. A class of such medicinal plants are those that are regarded as grasses and are usually taken for healing purposes. The plants investigated are lemon grass (Cymbopogan citrates), Spear grass (Imperata cylindrical) and Carpet grass (Eleusin indicageartin). The plants were assayed for their radionuclide contents by means of gamma spectrometry using a shielded and well calibrated NaI(Tl) detector coupled to a computer interfaced multichannel analyser, quantum Tm MCA 2100R. Results of the analysis showed that the radionuclides detected in the grasses around the oil and gas facilities belong to the primordial radionuclide series of 238 U and 232 Th as well as non serial 40 K. On the average, the values for lemon grass has 238 U (15.3 + 1.7 Bqkg -1 ), 232 Th (1.1 + 2.7 Bqkg -1 ) and 40 K(67.9 + 7.4 Bqkg -1 ). In spear grass, 238 U (15.8 + 2.4 Bqkg -1 ), 232 Th (1.7 + 4.3 Bqkg -1 ) and 40 K(69.3 + 9.4 Bqkg -1 ) were determined while carpet grass recorded 40 K (70.2 + 11.6 Bqkg -1 ) with 238 U(16.0 + 1.9 Bqkg -1 ) and 232 Th(1.6 + 4.2 Bqkg -1 ). The measured levels of the radioactivity in the samples translated to very low values of the annual effective dose equivalent, implying safe level of radiological health consequences. No significant difference was determined between radionuclide contents of samples of medicinal plants around oil and gas facilities and samples of the same species of medicinal plants from an undisturbed and virgin location in Nigeria where industrial activities, waste dump nor is farming practised. However, no trace of artificial radionuclide was determined in all the samples assayed in both areas, hence, measurements can be taken as representing baseline values of the radionuclides in medicinal plants in the areas.

Natural radioactive materials under certain conditions can reach hazardous radiological levels. Therefore, it becomes necessary to study the natural radioactivity levels in soil to assess the dose to the population in order to determine the health risks and to obtain a baseline for future changes that may occur due to human activities.The motivation for this study was the devastating civil war that took place in Nigeria from 1967 to 1970, in which the study area was one of the battle fields. Th and 40 K ranged from 15.42±1.10 to 40.99±1.36 nGy/h. The radium equivalent activity (R eq ) and the annual effective dose rates were also calculated and found to vary from 33.39±2.44 to 85.07±2.96 Bq/kg and from 18.91±1.35 to 50.27±1.69 µSv/y respectively. These values were found to be within the same range as recommended values . The study also indicated that 137 Cs detected at three locations is an indication of the presence of artificial radionuclides which can be linked to the war that took place in the ancient town of Ore.

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