Assessment the health Risks of Radionuclides 238 U, 232 Th and 40 K that influencing on Wheat: case study in Al-Qadisiyah, Iraq

. Wheat is one of the most important ingredients used by the Iraqi people. The significant aspect of this study is the detection of radioactive isotope absorption in grains. The nuclear detector NaI (Tl) was used to measure the natural concentration of radionuclides 238 U, 232 Th and 40 K in wheat and soil. The average concentrations of these radionuclides in the soil samples were 7.774±0.465, 2.301±0.217 and 270.985±3.322 Bq.kg − 1 for 238 U, 232 Th and 40 K, respectively. Their average concentrations in the wheat samples were 7.774±0.465, 1.383±0.179 and 0.361±0.086 Bq.kg -1 for 238 U, 232 Th and 40 K, respectively. The average values of the transfer factors (TFs) from soil to wheat of 238 U, 232 Th and 40 K were calculated as 0.069, 0.179 and 0.175, respectively. These TFs showed that the movement of these radionuclides in the soil samples was poor compared with previous results. The concentrations found were less than the allowable limits of the United Nations Scientific Committee on the Effects of Atomic Radiation. Therefore, the findings revealed no major risks to human health and edible grains are healthy to consume.


Introduction
The natural radioactivity and decay products in the biosphere of nuclides 238 U, 232 Th and 40 K are studied through their transfer factors (TFs).TFs are crucial because of their pervasiveness and longevity in a setting.TFs move from one environmental compartment to another, eventually reaching humans and exposing them to continuous radiation.The primordial radioactivity of nuclides 238 U, 232 Th and 40 K in soil, with different activities, is connected to the nature of the parent rock during soil formation (Orosun et al., 2022).One of the common routes for radionuclide transfer to people is soil → grains → human body (Khandaker et al., 2016).These long-life naturally occurring radionuclides can be passed to grains with nourishment items gathered from different parts of grains during mineral absorption, entering edible parts.The use of these grains or their parts by people results in a continuous radioactive dosage.Considering that the spatial variety of natural radiation in soil and related radiation exposure through specific food materials are significant, the existing literature is based on soil studies in high-background zones.Alternatively, radioactive spiked nutrient solution or soil can be used in pot experiments (Ghajarbeygi et al., 2022;Hidouri, 2017;Mitchell et al., 2013;Shahbazi-Gahrouei et al., 2013).The aforementioned studies only approximate processes that occur in a complex soil solution, which does not accurately represent the situation in a given region.Information on trace nuclides taken up by soil and plants under natural field conditions, particularly for determining the history of radiation in a region, is rare.Soil characteristics, such as pH and clay mineral, calcium, potassium and organic matter contents, along with soil modification processes, such as the application of fertilisers, should be considered.These studies merely approximate the processes that occur in a soil solution, which are complicated; they do not represent the actual situation in an area.Data on trace nuclide uptake by soil and plants under natural field conditions are apparently scarce, particularly from the contexts of pH and clay mineral, calcium, potassium and organic matter contents, along with soil modification processes, such as application of fertilisers (Willy et al., 2019).The scientific definition of TF is as follows: the ratio of the concentration of activity in the grain mass to the concentration of activity in soil masses for all samples (Rakić et al., 2014).TF is a crucial variable in research for evaluating the effects of radioactivity emitted into the environment, either intentional or unintentional.The extent of contamination in grain TFs from soil to crops varies depending on soil type, agricultural management (fertilisation), crop type, regional climatic conditions, soil chemical and physical qualities and radionuclide formation (Addo et al., 2013).Wheat is high in vitamins, minerals, carbohydrates, dietary fibres (Ghnimi et al., 2017).lipids, salt proteins and pectin (Baliga et al., 2011;Karizaki, 2017).The radiation content of agricultural soil and the soil-to-what TFs of radionuclides have been reported to be high in several investigations (Kritsananuwat et al., 2017;Mohammad et al., 2013;Okeme et al., 2016).Iraq is considered one of the most famous countries in wheat cultivation, especially in the central regions of Iraq.Due to the presence of many environmental pollutants resulting from the remnants of wars, therefore, it was necessary to calculate concentrations of radionuclides in wheat, which is considered the main food not only for the Iraqi people, but Iraq is rate a source of wheat export to neighbouring countries.Accordingly, the current research aims to assess and investigate the levels of 238 U, 232 Th and 40 K in the farmlands of Al-Qadisiyah Governorate in Iraq, along with TFs from soil to wheat.To make sure that the crop is suitable for consumption and export or not.

Study area
Al-Qadisiyah Governorate, which is found in Iraq, is around 180 km south of Baghdad, Iraq's capital.It has a land area of 8153 km2 and located at coordinates 31.17-32.24N,44.24-45.49E(Kadhim et al., 2020).As shown in figure 1. Soil and wheat samples were collected from agricultural lands in 20 different areas across the city for this research.

Collection and preparation of samples
A total of 20 samples for each type of soil and wheat were collected from separate locations in Al-Qadisiyah.All the samples were exposed to the sun for 2 days to obtain the desired humidity level.Thereafter, the samples were heated in an electrical oven for 2 h to achieve a temperature of 100 C°.Subsequently, the samples were powdered and passed through a mesh with a specific size of 75 μm in accordance with standard mesh size (Aswood et al., 2013).

Background and sample measurement
The background is one of the most critical factors that influences the measurement of samples.The background spectrum was measured with a 1 L plastic container on the detector and counted at the same time for sample measurements.As shown in figure 2, the background spectrum was taken in a research laboratory on October 22, 2020 with a measurement time of 15000 s.

Fig.2 Background spectrum by NaI (Tl) detector
Low-level radioactivity samples from the environment are frequently measured in Marinelli beakers that are especially made to provide higher detection sensitivity.Full energy peak efficiency variations are observed in this geometry for different sample types due to selfattenuation effects.A 1 L Marinelli beaker made from polypropylene was used in the experiment.The effect of self-absorption, which must be corrected, limits the precision with which this Marinelli geometry can determine the activity.The net area under the corresponding peaks in the energy s was calculated for each sample with the MAESTRO-32 data analysis kit by subtracting the count due to background sources from the net area of a given peak.Photo peaks are not separated well at low gamma energy, and thus, measuring individual concentrations of activities is difficult.At high gamma energy, however, image peaks are isolated well in those obtained during our observations from the gamma rays released by the progenies of 232 Th and 238 U, which are in secular equilibrium with them, whilst 40 K is directly calculated from its line of gamma 1460 keV.The main steps of research process are summarized in figure 3.

Specific activities
The activities of 238 U in the samples were determined using the energy peak of 214 Bi (1764 keV).Similarly, the activity of 232 Th was determined using the 2614 keV peak of 208 Tl.The activity of 40 K was determined from the energy of 1460 keV.The analytical model used to calculate the activity in Bq.kg −1 for soil and wheat samples is presented in Equation (1) (Salih, Hussein, et al., 2019) where N is the net of counting under the corresponding photo peak; t is the time of counting in (s), which is the absolute value of the probability gamma emission transition; m is the mass of a sample (kg) and ε is the efficiency of the detector in a particular gamma energy.

Transfer factor (TFs)
The ratio between the consternation of radionuclides in wheat and the consternation of dry soil is called TF (Al-Hamzawi, 2015).The corresponding TFs of different plants, which are related to the activity of a given radionuclide ( 238 U, 232 Th and 40 K) for all signal part crops, are determined for all the samples by using Equation ( 2

TFs from soil to wheat
TFs for wheat samples were established in the current study.The equilibrium concentration difference between two physical conditions, such as the ratio of a concentration of an element in dry and wet environments for dry crops to that in dry soil, is known as a TF, which is an important measure for radiation estimation (Salih, Aswood, et al., 2019).For 238 U, 232 Th and 40 K, the radiological TF between soil and wheat varies between (0.018 and 0.202), (0.009 and 0.399) and (0.077 and 0.355), respectively, as indicated in Table 4. Radiological TF from soil to wheat is generally dependent on the type of grains, type of soil and position.The wheat absorption of an isotope from soil is influenced by several factors, such as texture, cation exchange capability, interchangeable captions, pH, clay content, dominant clay minerals and organic matter content.It also varies depending on the physical and chemical types of radionuclides, plant species and development rate.

Conclusions
From the experimental and computational work on the natural radioactivity of ِAl-Qadisiyah, villages in central Iraq, we can conclude the following: For all the samples collected from Al-Qadisiyah, the radiological nuclide concentrations of soil and wheat and soil-to-wheat TFs were determined.Radiological nuclide concentrations in soil vary depending on soil type, location and the geological composition of the area, in accordance with current studies.However, the findings of this work indicate that grain absorption does not pose a significant safety concern to humans.Monitoring is on-going and must be performed to determine maximum U activity because radiation in the atmosphere is undesirable, as is environmental pollution resulting from wars.The results of the radiological TFs show that the soil-to-wheat TF is low, which may be attributed to the length of time it takes to cultivate wheat and the amounts of water and fertilizers used.These results are consistent with the literature, whether in cities inside Iraq or other countries famous for growing wheat, as shown previously in Table 3.Also, it is compatible with the requirements of the World Health Organization.The interpretation of the 238 U, 232 Th, and 40 K TF data presented here for the studied crops along with the data gathered from literature strongly suggests that transfer factors are essential to obtain an accurate radiological assessment.Finally, the results of this study will hopefully form valuable baseline data on the behaviour and concentrations of natural radioactivity in soils and wheat grown in the important agricultural environment of Iraq.Our results in the study region can hopefully improve the scientific knowledge for future studies.Also, to increase the reassurance of the population and neighbouring countries that what is exported to them from wheat is safe and subject to a recent study.In conclusion, we expect that future research will be related to other important samples that affect humans and their health.Also, we expect to study in other agricultural areas inside and outside Iraq and will make a comparison between them.

Table 2 .
Specific Activity of natural radioactivity in wheat from Al-Qadisiyah Governorate

Table 4 .
Factor of Transfer of natural radioactivity from soil to wheat in Al-Qadisiyah Governorate