Advanced Techniques in Biology & Medicine
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Radioactivity Natural Environmental Radiation in Middle of Iraq Governorates

Entesser F.Salman^1*, Mohsin Kadhim Muttelab¹ and Jwad K.Manii^{2 *}Correspondence: Entesser F.Salman, Department of Science-Physics, University of Babylon, Iraq, Email:

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Introduction

The importance of soil in general is the fact that it represents the important and main centre of the various organisms of plants and microorganisms and many animals, and is the first and main component in the production of food necessary for human life wherever it exists, so any negative impact or pollution of any kind affects the soil affects directly on all the living things that are connected to them and to the human who lives on them [1]. Radiation pollution is a form of pollution with global influence. Since ancient times, humans have been subjected to natural radiation from cosmic rays and other radioactive materials found in the earth's crust since its inception, if they are composed of radioactive neutrons. The particles of alpha, beta and gamma are dissolved to the human body through food [2].

Natural radionuclides found in air, soil, water and building materials are the main source of radiation background nature three important isotopes are uranium, thorium and potassium, uranium heavy and radiant metal dissolves by emitting alpha particles (α) with a constant dissolution of 1.5X10-10 each year and with a radioactive activity of 12.4 X 103 Bq/kg and its density at 25°C (19.05 g/cm3) Characteristics: silver white, Toxic, melting point (1132°C ). Uranium is found in various amounts in nature in rocks, soil, water, air, plants, animals, human body and elsewhere. The concentration of uranium depends on the soil type and then on the type of rock forming the soil [3].

Uranium was originally found in two groups of rocks that have long existed in addition to groundwater and fractures in the soil. The first group is granite rocks and contains about 4 gm/ton. In this group, the liquid magma comes from the underground with uranium. In this case, we get rich raw materials with a high percentage of uranium (5%). The second group is deposits accumulated on the mountainous masses, In general, uranium is found as a byproduct in some other materials, such as phosphates and gold ores, as in South Africa, and sometimes uranium is accompanied by coal ores [4].The highest concentration of uranium is in acidic volcanic rocks, but its concentration in igneous rocks depends on the abundance of silicates. The rocks that contain silicates have high concentrations of uranium. It accounts for about 99.27% of the total natural uranium, about 0.72%, about 0.0055%, and uranium isotopes of half–life, the half–life of uranium is around 4.5 billion years, uranium about 700 million years, uranium, (About 250,000 years). It is believed that much of the heat of the Earth's surface is produced by uranium radiation. There have been several important exploratory studies that examined the radiation background in the soil for the three natural radionuclides that emit gamma doses measurement soil radiation content is important in appreciation the risks resulting from it, such as anemia, leukemia, cancer, hepatic skin and mental retardation affects children whose mothers have been exposed to this radiation during pregnancy [5]. Approximately 4.7 annual effective doses received by persons as recognized UNSCEAR 2016 other human health damage caused by exposure to uranium is the genetic effects of reproductive cell damage, which leads to genetic mutation [6].

Materials and Methods

Study area

The study area extends between longitudes (44o00' 00'' to 45o16' 00'' E) and latitudes (31o27'00'' to32o58' 00'' N). The Middle Euphrates is the geographical area in the south of Baghdad in the Euphrates region, which is located in Najaf, Karbala, Diwaniyah and Babylon Together, these governors comprises an area, of 98. 87 thousand square kilometres, equivalent to 22.7 percent of the country's total area of 438,317 square kilometres. It is divided between two natural regions the western plateau and the sedimentary plain, most of which are only a few meters above sea level [7].

Sample preparation

The sites were selected from the governorates for the purpose of studying their radioactivity locations at a depth of 15 cm, about 1.00 kg were neatly packed in well-labeled polyethylene bags properly sealed and transported to the radiation laboratory that were sifted and removed the impurities and then dried samples and stored for 30 days before counting to allow secular equilibrium to be attained between 222Rn and its parent ²²⁶Ra in uranium chain before measurement using a gamma spectrometry system.

Samples analysis

Usinng γ-ray spectrometer Iodide Sodium activated by Thallium NaI (TI) of (3"×3") crystal dimension, supplied by (Alpha Spectra, Inc 12I12/3), coupled with a multi-channel analyzer (MCA) ORTEC–Digi Base with range of 4096 channel joined with ADC (Analog to Digital Convertor) unit, through interface, the spectral data was converted directly to the PC of the laboratory introduced using (Maestro-32) software. Measurements were made to check the background level of radioactivity in the laboratory the γ-ray photo peaks corresponding to 11747 kev of 40K, 203kev for 238U and 62kev of 232Th. The calibration of the detector enables us to find the linear relationship between the pulse coming out of the detector and the gamma energy falling on the crystallization of the detector. The relationship between the channel number in the multichannel analyzer and the spectral line energy of the studied isotopes. The (MCD) consists mainly of memory with storage locations equal to the number of (MCD) channels where the pulses are stored in these channels according to the energy of each pulse.

Evaluated of radiation hazard parameters

Estimating the risk factor for cancer due to exposure to radiation was an important issue that was appreciated by several international organizations such as the International Commission on Radiological Protection [8], and the United Nations Scientific Committee on the Effects of Atomic Radiation [9]. The absorbed dose in the air is ADRA and measured at a distance of one meter from the surface of the ground containing the naturally occurring radionuclide depending on the concentrations of natural radionuclides in the soil, calculated by equation [9]

A=Cnet/(ε.Iγ m.t)∓√(Cnet )/(ε.Iγ m.t) (1)

C_net the net count, ε efficiency of detector, t: time for spectrum, m: weigh of the samples in kg. Iγ the transition probability of the emitted gamma ray. The outdoor absorbed dose rate also evaluted by[10]

ADRA (nGyh⁻¹)=0.642A+0.604A+0.0417A<80nGyh⁻¹ (2)

The annual effective dose rate defined by equation [11]:

AEDE=(0.49A_U+0.76 A_Th+0.048 A_K) × 8.76 × 10^-3 (3)

Assumption that human about 20 of his time out calculated formulas as [12]:

AEDE (outdoor) (μSv/yr)=AEDR(nGy/h) X 8760h X 0.7Sv/Gy X 0.2 X 10^-3 (4)

AEDE (indoor) (μSv/yr)=AEDR (nGy/h) X 8760h X 0.7Sv/Gy X 0.8 X 10^-3 (5)

When 8760 time conversion factor, dose conversion factor is 0.7SvGy^-1, but occupancy coefficient 0.2 the represents that human spends about 20 of his time outdoor and indoor 0.8 [12]. The excess lifetime cancer risk (ELCR) for outdoor exposure, which represented the risk of developing cancer of time as a result of radiation exposure from natural radionuclides in the air can be calculated from equation [13]:

ELCR=AEDE×DL×RF×10^-3 (6)

DL: is the average duration of life (estimated to 66 years), and Risk Factor by samble RF (Sv^-1) this mean fatal cancer risk per Sievert ICRP uses RF as (0.05) for public [8]. The gamma Index (Iγ) was estimated using equation [14]:

Iγ=A_U/150(Bqkg⁻¹) + A_Th/100(Bqkg⁻¹) + A_K/1500(Bqkg⁻¹) (7)

Annual Gonadal Equivalent Dose (AGED). The effects of three radionuclides on bone marrow and bone marrow cells were assessed using the dose equivalent calculation [15]:

AGED (Sv/yr)=3.09A_U + 4.18A_Th+0.314A_k (8)

Results and Discussion

Measured activities for three isotopes (²³⁸U, ²³²Th and ⁴⁰K and ²³⁵U) with radium equivelent radiation dose location points are calculated by equations (1) and (2) respectively displayed in Table 1. The activity concentration ²³⁸U, ²³²Th and ⁴⁰K radionuclides are within the ranges 0.19 ± 0.07 Bqkg^-1 to 30.52 ± 0.91 Bqkg^-1, 0.34 ± 0.03 Bqkg^-1 to 32.45 ± 0.83Bqkg^-1, and 374 ± 3.69 Bqkg^-1 to 211 ± 2.77 Bqkg^{-1 238}U, ²³²Th and ⁴⁰K respectively in the area of study, The correlations between both the probability of cancer and the activity of uranium radiation were 0.3724 it shows that the relationship of uranium to cancer is weak in the study area (Figure 1).

Table 1: Activity concentration (Bq/kg) of natural radioactivity in soil samples for Babylon city.

Figure 1. Map of distribution of sites in middle Euphrates region (Karbala, Babylon, Diwaniyah and Najaf).

Conclusion

The activity concentration of the naturally occurring radionuclide of 238U,232 Th and 40K in soil samples were determined by gamma spectrometry, the correlations between both the probability of cancer and the activity of uranium radiation were 0.3724 it shows that the relationship of uranium to cancer is weak in the study area but correlation between ELCR activity of 232 Th and 40K radiation greater than this value. The correlation between probability of cancer and internal and external absorbed dose was high in study area. Excess lifetime cancer risks factor was directly determined using the annual effective dose radiation which is solely dependent on the measured radiation dose rate in the area of study. Correlation ADRA (nGyh−1) both outdoor and indoor with AGED Annual Gonadal Equivalent Dose (AGED) very high within the study area.

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