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Background
In most areas in the world, the natural radioactivity varies only within a certain limit, while there are a few regions that are known to have high background radiation areas. These are due to the local geological properties and geochemical effects that cause increased levels of terrestrial radiation [1]. A very high background radiation area was found at Ramsar in Iran, a type of area known as a High Level Natural Radiation Area (HLNRA) [2].
The major contribution to radiation exposure comes from natural radionuclides of both terrestrial and cosmogenic origins, which have caused approximately 85% of the annual total dose of the population [3]. Among natural radionuclides, the ?-emitters are significant due to their potential internal human radiation exposure [4]. As radium chemical behavior is similar to that of calcium in the body, and radium has been known to be one of the most radiotoxic radionuclides, this radionuclide was therefore chosen to be determined in market food samples [5].
Natural and artificial radioactivity measurements have been carried out in foodstuffs [6-10]. Also, a number of studies have been carried out on market foodstuffs [11-15]. The United Nations Scientific Committee on the Effects of Atomic Radiation’s report is the relevant literature that contains major reviews on the radioactivity of foodstuff [3]. Different radiological measurements and epidemiological studies have been carried out on Ramsar in Iran, due its importance as an HLNRA [1, 16]. Few investigators have measuring the radioactivity of foodstuff in Iran [5, 17, 18]. Among these literatures, a study has been carried out to experimentally determine the vegetable-to-soil concentration ratio (CR) of 226Ra in HLNRAs of Talesh Mahalleh in Ramsar. An estimation of the effective dose due to the ingestion of only edible vegetables, rather than all the daily diet, has been taken from a critical group rather than all the residents in this region [19]. Another study has been conducted to set a proper method for measuring the low concentration of 226Ra and 224Ra in fruit and vegetable samples taken from Ramsar [4].
As consumption of food is usually one of the most important routes by which natural and artificial radionuclides can intake by the human body, an evaluation of radionuclide levels in different food samples and residents’ diets is very...