Abstract
The specific activity concentration and the derived Annual Effective Dose(AED) in three types of vernonia cultivated and consumed within and outside Cameroon were measured by means of a well-calibrated high-purity germanium detector. Vernonia samples were collected directly from the production farms, oven-dried to a constant mass, crushed, sieved and sealed for at least a month before analysis. The specific activity of 238U in the three types of vernonia ranged from 20 - 50 Bq kg-1 with an average of 42 ± 15 Bq kg-1, 232Th from 9 - 22 Bq kg-1 with an average of 17 ± 7 Bq kg-1 while 40K ranged from 115 - 460 Bq kg-1 with an average of 302 ± 36 Bq kg-1. The average AED for 40K, 238U and 232Th were 0.15, 0.92 and 0.92μSv y-1 respectively. 238U and 232Th show the same trends both for the regional distribution of the radioactivity content and the AED. The discrepancies in our data can be attributed to many factors such as geological formation, foliar deposition, type and age of the plant, etc. Although the results obtained represent only some fractions of the standard limit, but they are within some range obtained in other countries.
Highlights
Exposure to ionizing radiation is generally regarded as undesirable at all levels no harmful effects are known to follow very low-level exposures
The purpose of this study is to identify radioelements contained in the edible vernonia cultivated in Cameroon, evaluate their specific activity concentration, and derive the Annual Effective Dose (AED) resulting from their consumption
The distribution of the average activity concentrations of the radionuclides determined from the measurement of the various types of vernonia analyzed is shown in Table 2 and Figure 2
Summary
Exposure to ionizing radiation is generally regarded as undesirable at all levels no harmful effects are known to follow very low-level exposures. Considerable attention has been given to low-level exposure arising from naturally occurring radionuclides, 238U, 232Th, their decay products and 40K. Natural radionuclides are present in air breathed by humans, in food [4], drinking water [5,6] as well as the ground from which human settlements are built [7]. Naturally occurring radionuclides are distributed among body organs according to the metabolism of the element involved, which normally exhibits varying sensitivities to radiation [8]. Radioelements contents have been measured in various food and drinking water samples by several methods, but their concentrations differ from one place to another. Previous studies have shown that there are three food categories, namely: fish and shellfish, cereals (excluding rice) and vegetables, found to be the main contributors to the daily intakes [9]
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