Determination of Food Crops Contamination in Osun State, Nigeria Due to Radium-226, Thorium-232 and Potassium-40 Concentrations in the Environment

Abstract

One of the three goals of the United Nations for sustainable food security is to ensure that all people have access to sufficient, nutritionally adequate, and safe food. The south-west area of Nigeria especially Osun State is home to some of the most important minerals, which include bitumen, gold, kaolin, salt limestone, tantalite, coal and phosphate. As a result of the mineral occurrence, some parts of Osun State have become associated with significant levels of natural radioactivity. The exploration and exploitation of these minerals are known to have enormous consequences on the environment. This work is to measure the baseline radioactivity levels in some major food crops in Osun State and hence predict the potential radiological health effects. The study area (Osun State) has a total land mass of about 12820 km2, with a projected population of 5.1 million inhabitants. Osun State lies within latitudes 07o00 N and 08o25 N and longitudes 04o00 E and 05o11 E. Maize, Yam and cassava tubers that constitute the major food nutritive requirements were collected directly across farmlands in the State. The sampling locations were purposely chosen by considering the possibility of mineral resources, water resources, industry and farmlands. In order to have a total coverage of the study area, Osun State was divided into eight zones comprising the thirty local government areas in the State. Maize, yam and cassava were dried at room temperature until a constant weight was achieved. They were ground, homogenized and 250 g sealed in 1-liter Marinelli beaker and kept for 28 days in order to attain secular equilibrium before the gamma counting. The activity concentrations of Ra-226, Th-232, and K-40 were determined in the food samples using γ-ray spectrometry in the Centre for Energy Research and Development, Obafemi Awolowo University, Ile-Ife. The mean activity concentration of Ra-226, Th-232 and K-40 for yam were 1.72 ± 0.10 Bqkg-1, 2.24 ± 0.21 Bqkg-1 and 37.84 ± 2.40 Bqkg-1 respectively. The content of the radionuclides in maize gave a mean value of 2.49 ± 0.48 Bqkg-1 for Ra-226, 2.12 ± 0.06 Bqkg-1 for Th-232 and for K-40, the mean value is 30.92 ± 2.15 Bqkg-1 . The mean specific radionuclide concentrations in cassava is 2.00 ± 0.41 Bqkg-1 for Ra-226, 1.81 ± 0.12 Bqkg-1 for Th-232 and 40.35 ± 3.94 Bqkg-1 for K-40. The committed effective doses were 0.66 µSvy-1 for the consumption of yam, 0.54 µSvy-1 for maize, and 0.66 µSvy-1 for cassava which are lower than the annual dose guideline for the general public. Therefore, the values obtained in this work show that there is no radiological contamination of foodstuffs consumed in Osun State.

Assessment of Natural Radioactivity and Radiological Hazard indices in Cassava Cultivated in Oil Producing Area, Rivers State, Nigeria

“…Primordial radionuclides of 238 U and 232 Th decay series are of great importance since they are relatively abundant and some (like 228 Ra and 226 Ra which are respectively the decay product of 238 U and 232 Th) are highly toxic in terms of radiation exposure due to their gamma ray emitting potentials (Ocheje and Tyovenda, 2020). Radiation has been implicated in the development of malignant disease and very probably, of other damage to human health (Nwankpa, 2017).…”

Radiological Impact Assessment of Farm Soils and Ofada rice (Oryza sativa japonica) from Three Areas in Nigeria

“…The United Nation's advocacy against the consumption of food contaminated with radionuclides has motivated various authors in the field of environmental radioactivity to continuously assess the health impact of radionuclides in various food matrices across the globe. In fact, the potential dangers envisaged in internal radiation exposure of human have encouraged many authors to study the radioactivity levels in various food items from different parts of the world (7)(8)(9)(10)(11)(12). The estimated amounts of each radionuclide that are absorbed into the human body organs can be determined if the concentration of different radionuclides in a food item is measured and the consumption rates of the foodstuff by individuals are known.…”