Evaluation of the risk of cancer due to natural radioactivity in some grain-based foodstuffs

Received: 09-Jul-2023, Manuscript No. OAR-23-109316; Accepted: 20-Aug-2023, Pre QC No. OAR-23-109316 (PQ); Editor assigned: 12-Jul-2023, Pre QC No. OAR-23-109316 (PQ); Reviewed: 26-Jul-2023, QC No. OAR-23-109316 (Q); Revised: 10-Aug-2023, Manuscript No. OAR-23-109316 (R); Published: 25-Aug-2023, DOI: -

Introduction

For the routine control of environmental pollution, limits are normally placed on the release of potentially harmful contaminants that may affect water, air, or soil and cause damage to the ecosystem or to human health. In the case of foodstuffs, levels of contaminants in the product are usually regulated, but primary control is nevertheless aimed at the prevention of contamination [1]. Natural radiation comes from many sources, including more than 60 naturally occurring radioactive materials found in water, soil, and air, as well as natural radon gas [2]. The sources of natural radioactivity are divided into three main types: cosmic rays, radionuclides generated as a result of cosmic rays and radionuclides of terrestrial origin [3].226 Ra with half-life 1620 (y) belong to 238U chain is one of the main pollutants in the natural radiation environment and there is widely in different ecosystems. Higher solubility of this element than uranium causes this element be washed by underground water and brought to the surface. This element is chemically similar to calcium and absorbed by plants through the soil and then through the food chain enters human’s body. Almost 70% of 226Ra is accumulated in the bones and the rest spread to soft tissues of the body[4]. This radionuclide is a bone-oriented element and due to its long halflife remains in bones. However because of alpha radiation serious dangers such as bone marrow cancer can threat human health. Average annual absorption of 226Ra through the food and drink is about 19 Bq in global level that causes effective dose equivalent approximately 3.8 μSν in a year [2]. The main stages of infection entering the human food chains are [5]:

• To be uptake radionuclide by plants through leaves or roots and transferring it to fruit or in cereal and legumes to grains.

• Radionuclide transport from plants, fodder animals and animal products.

• Finally human in biological cycle, both through the polluted plants and animal products can be affected.

Therefore it is necessary to pay attention to radioactivity pollution and their mechanism absorption. Amount of radioactive pollution in various food and plants according to their absorption capacity is different. Consumed diet, consumed dosage, preparation site, and ways of preparing food, whether vegetable or animal influence on the effects that plant pollution can put on people. Considering that the main objective of the study of radioactive contamination in plant sources is the impact on humans, makes necessary to do this type of studies [3-5]. Also, the use of phosphate fertilizers in agricultural land makes multiplier radionuclide levels in soil and eventually plant contamination [6, 7]. Therefore, it is worth studying the radioactivity in commonly consumed foodstuffs and estimating the potential risk ratio in order to protect the health of the consumer, so as wheat flour, rice, corn and past was chosen because it is a traditional product prepared using wheat flour (the fiber in it makes up to 3.4%) in addition to being one of the types of pasta ,considered one of the most important common foods manufactured from grains, due to its ease of preparation, long shelf life, storage and low cost .The recipes of wheat fl our from which wheat flour ,rice, corn and past are made should not exceed the percentage (moisture in it is 15%, gluten 30% and acidity 5 degrees) [8]. Wheat flour, rice, corn and past is classified into basic classes, relative to the raw materials from which it is made and various other additives, also the nutritional value of wheat flour per 100 grams (9 gm of protein,78 mg of carbohydrates, 22 mg of Calcium, 92 mg of phosphorous and 2 mg of Iron) [9]. Due to the large consumption of this food item, many studies have been conducted; the radiation risk factors were calculated for some types of pasta available in the Iraqi market [10]. Study of radioactivity and estimation of risk factors for radionuclides for some types of foods such as pasta in Jordan [11], and Measuring some important parameters and concentrations of some elements in wheat flour in China [12]. It has also been studied the activity concentrations of 226Ra, 232Th and 40K in the selected vegetables collected from different locations of Cameron Highlands, Pahang, Malaysia [13]. Specific activity in (Bq.kg^-1) were estimated in unique kinds of flours that are accessible in Iraqi markets and average annual committed effective dose [14]. Measuring the level of radioactive contamination of selected samples of Sugar and Salt available in the local markets in Najaf governorate/Iraq [15]. The radiological hazard was measured in ten samples of Breakfast Cereals which collected from the Iraqi market. The corresponding radiation dose amounts and risk indices were also calculated. The mean concentrations of 226Ra, 232Th and 40K were found to be 18.195, 20.965 and 796.500 (Bq.kg^-1) [16].Therefore, we deemed it necessary to study this type of food item and calculate some important transactions related directly and significantly to human health, as well as in order for a database of wheat flour, Rice, corn and pasta material to be available.

Sample preparation

Seventy six samples of the most available type’s food (wheat flour, Rice, Corn and pasta) among various brand names were collected from the local markets in Iraq. To remove moisture, the samples were dried in an electric oven at 100ºC for 24 hours. After drying, the samples were crushed into a fine powder to pass through a 2 mm mesh sieve. For radiation measurements, Two reference materials were packed into the same standard size beakers for efficiency calibration. Been preparing the 80 samples from wheat flour, rice, corn and pasta of local and imported origins were collected, each sample weighed 500 grams, then the samples were ground into powder and stored in special containers for NaI(TI) detector. The storage time was one month, after that, the samples were ready for measurement. Time was determined to measure samples was 3 hours also all samples were placed in the Physics Laboratory at the Faculty of Education, University of Kufa, to be ready for measurement

Mechanism of Activity concentration measurement

Concentrations of normal radioactivity in Wheat flour, rice, corn and past samples, identified using gamma ray Na(TI) detector, which is protected by lead (15) cm thick on all sides including the upper part to reduce the radioactive background .The Wheat flour, rice, corn and past samples were placed on the top of crystal and using the gamma ray spectrometer and multichannel analyser,count spectra were obtained for each of the Wheat flour, rice, corn and past samples.

Statistical analysis

The relation among the parameters derived from natural radionuclides and the p-value is examined using statistical analysis (ANOVA), and it is 0.05 and not a lower or higher value that determines, whether the result is statistically significant or not. For statistical analysis in this paper, SPSS by Windows, standard version 20.0, was utilized as the primary statistical tool [17].

Result and Discussions

According to the results of gamma-ray spectra, the specific activity value of 226Ra, 232Th and 40K were calculated in a unit of ( Bq.kg⁻¹) was measured using Equation below [18]

Where An is the specific activity (S.A) of radionuclide in the samples, G is the count rate in (CPS) for samples, B is the count rate in (CPS) for background, t is represent the time of spectra acquisition, εγ is detection efficiency, IG is emission probability of γ ray and, mass in (Kg) where the results of (S.A) was Fixed by Research Published [10, 14, 19].

Representative alpha index (I_α )

From the equation below, values were obtained of alpha index which was calculated for the Wheat flour, rice, corn and past samples, it was found that it was much less than one and with an average equal to 0.0055 ,which does not pose any threat or danger. The alpha index (Iα) was calculated from the equation [20]:

Activity Utilization Index (AUI)

In order to calculation of air dose rates from different groups of three radionuclides in wheat flour ,rice, corn and past by applying the appropriate conversion the indices is estimated (AUI) which given by the following expression [21]:

Where fra, fTh and fkfk are the fractional contribution to the total dose rate in air due to gamma radiation from the actual concentration of 226Ra , 232Th and 40K , respectively (NEA– OECD) report. The average value equal to 0.0157 , this value of AUI less than two which corresponds to an annual effective dose (less than 0.3 mSv.y^-1) [22].

Internal radiation hazard Index (H_in)

The internal hazard index is used to control internal exposure to 222Rn and its radioactive progeny in addition to external exposure to radon gas, dangerous for the respiratory system. Which calculate from activity concentrations of 226Ra, 232Th and 40K values of (H_in should be less than unity in order not to pose a threat of the population [23-25].

Absorbed dose rate in air (D_R)

Natural radionuclide decay in the soil is one of the major sources of human radiation exposure. This radiation level is different depending on the con-tent of minerals and radioactive elements of each region. Gamma radiation dose due to natural radioactive contents of the soil is important to population of the area that they live in. Absorbed dose rate in air for radionuclide were calculated based on provided guidance as follows [26].

In which ARa, AK, and ATh respectively are the average activity concentrations of 226Ra, 40K, 232Th in terms of Bq.kg.

Annual Gonadal Equivalent Dose (AGED)

Was also calculated due to that the reproductive gland is important due to its high sensitivity to radiation [27]. The latter index is classified as highly important in the UNSCEAR 2000 publication[28] .Therefore, it is essential to calculate the Annual Gonadal Equivalent Dose (AGED) depending on the specific activities of 226Ra, 232Th, and 40K [5]:

The Average Annual Committed Effective Dose (E_av.) to an individual, due to consumption of the four food groups studied by the ingestion of naturally occurring radioactive materials (NORMs) was estimated using the equation [29].

where, E_av. is the average annual committed effective dose, Cr is the consumption rate of radionuclides, the annual effective ingestion dose due to the consumption of wheat grains was calculated based on annual intake of 108 kg.y^-1(dry weight) of wheat grains ,42 kg.y^-1, 98 kg.y^-1 and 38 kg.y^-1 by adults in Iraq, and DCFi is the dose conversion factor for each radionuclide (2.8×10^-7, 2.3×10^-7, 6.2×10^-9) Sv.Bq^-1 for 226Ra, 232Th, 40K, respectively),and Ai is the activity concentration of each radionuclide .Using the same equation, the annual threshold consumption rate for a medicinal plant is obtained [30]:

where, E_av.= 0.3mSv.y^-1 for 5 E_av. is the threshold average annual committed effective dose due to ingestion of NORMs in the medicinal plants but equal 0.324mSv.y^-1, A_i is the activity concentration of radionuclide i, and DCFi is the dose conversion factor for radionuclide i (UNSCEAR, 2000).

Excess Lifetime Cancer Risk (ELCR)

Excess lifetime cancer risk (ELCR) is calculated using the following equation and presented in table (3) [31, 32].

Where E_av. (annual ingestion dose) where was less than the dose

limit of (250–400)*10^-3 [33], the annual equivalent effective dose which was calculated using its own formula [13] , DL and RF are Life span (70 years) and risk factor (0.05) per Sievert ICRP .The ELCR with an average value (0.0057) which was less than (2.5*10^-3) recommended by ICRP and WHO [33], from the results we obtained is that the risk of developing cancer is below the internationally recommended limits, so wheat flour, rice, corn and past samples are healthy for consumers.

Table 1, included 25 samples of different origins from wheat flour, by examining the results of the table, it was found that sample WG3 of Italian origin is the lowest in terms of the specific effectiveness of 226Ra and 40k nuclides, as well as in relation to the risk factors (Iα and Hin), but the concentration of 232Th and index AUI was the lowest in sample WG8 of British origin. However, the highest percentages were in the sample WG17 of Iranian origin for the concentration of 232Th and t he two factors (AUI and Hin). The sample of WG18 o f Iranian origin is also the highest in terms of 226Ra concentration and the alpha coefficient Iα, while the concentration of 40k was highest in the sample WG25 of Turkish origin. It can be said that the average concentrations of the studied samples and for all origins are less than the permissible limits globally.

Tab. 1. Origins of Wheat Flour samples with activity concentration and radiation hazard indices

Table 2, included 24 samples of different origins of pasta. By examining the results of the table, it was found that sample PM3 of Turkish origin is the highest in terms of the specific effectiveness of Radium-226 and Thorium-232 nuclides, as well as for the three hazard indices (Hin, AUI and Iα), but the concentration of potassium- 40 was the highest in sample PM1 of Turkish origin. But the lowest concentration was in sample PM18 of Italian origin for Radium-226 concentration, and sample PM24 of Indonesian origin for potassium-40. But the concentration of Thorium-232 and the three hazard indices were the lowest in the sample PM14(Iraq), and it can be said that the average concentrations of the studied samples and for all origins are less than the internationally permissible limits (UNSCEAR 2008).

Tab. 2. Origins of Pasta samples with activity concentration and radiation hazard indices

Table 3, included 18 samples of different origins of rice. By examining the results of the table, it was found that sample RC4 of Turkish origin is the highest in terms of the specific effectiveness of Radium-226 nuclide and the lowest concentration in the sample RC16 of Italian origin, but the concentration of Thorium-232 was highest in sample RC8 of Iraqi origin and lowest in sample 18 of Spanish origin . It was also noted from the table that the potassium concentration level and the three risk coefficients were the highest in the sample 8 of Iraqi origin and the lowest in the sample of Spanish origin RC18 except for the alpha coefficient Iα, which was the lowest in the Italian sample 16 and all treatments were safe from the health side.

Tab. 3. Origins of rice samples with activity concentration and radiation hazard indices

Table 4, included 13 samples of different origins of maize. By examining the results of the table, it was found that sample CN8 of Lebanese origin is the highest in terms of specific activity of Radium-226 nuclide and the lowest concentration in sample CN9 of Iraqi origin, but the concentration of Thorium-232 was the highest in sample CN7 of Iraqi origin and lowest in sample CN3 of German origin. It was also noted from the table above that the level of potassium-40 concentration was the lowest in sample CN4 of Britain and the highest in sample CN7of Iraqi origin. As for the three risk indices, the highest was in sample CN8 of Lebanese origin (Iα and AUI), but (Hin) was the highest in sample CN7 of Iraqi origin. It was also noted that alpha was the lowest concentration in sample CN9.

Tab. 4. Origins of corn samples with activity concentration and radiation hazard indices

AUI index hazard has a lower concentration in the sample CN3 Germany and the Hin have a lower concentration in the sample CN4 Britain(UK).

Natural radioactivity levels in samples of wheat flour, Rice , Pasta and corn were evaluated in the samples which collective from the markets in Iraq where was the radiation levels of the three nuclides 226Ra, 232Th and 40K , respectively, were below the global limits (30,35 and 400) Bq.kg^-1 .

Air absorbed Dose Rate (DR), equivalent Annual Gonadal Dose (AGDE), equivalent annual effective dose (Eav.) and lifetime cancer risk (ELCR) in wheat flour are documented in Table 5. The lowest values for them all were in the sample WG3 of Italian origin and the highest values in the sample WG17 of Iranian origin. As for the pasta samples, the values of the studied four parameters were the lowest in the sample WG14 Iraq, and the highest values in the sample WG4 Turkey. And for both groups, it was within the limits allowed by international organizations.

Tab. 5. Absorbed dose rate in air (dr), annual gonadal dose equivalent (agde), annual effective dose equivalent (eav.) and excess lifetime cancer risk (elcr) in wheat flour and pasta samples.

The air absorbed Dose Rate (DR), the equivalent Annual Gonadotropin Dose (AGDE), the equivalent annual effective dose (E_av.) and the lifetime risk of cancer (ELCR) in wheat flour were also documented in Table 6. The lowest values of them all were documented in Table 6. The sample WG18 of Spanish origin had the highest values in the sample WG8 of Iraqi origin with respect to rice, while for the maize samples the values of the studied four parameters were the lowest in the British sample WG4, and the highest values in the sample WG7 Iraq for DR and AGDE, but Eav. and ELCR the highest in the sample WG8 Lebanon and for the two groups was within the limits allowed by International organizations. All comparisons showed the most important variables in Figures 1 and 2

Tab. 6. Absorbed dose rate in air (dr), annual gonadal dose equivalent (agde), annual effective dose equivalent (eav.) and excess lifetime cancer risk(elcr) in rice and corn samples.

Figure 1: Comparison of Absorbed dose rate in air DR (nGy.h^-1) for the four studied foodstuff types

Figure 2:Comparison of annual gonadal equivalent dose aged μsv.y⁻¹ for the four studied food types

Also, this study revealed absorbed dose in air (DR) for two groups were to be lower than the global average value of 55 nGy^-1h [34].

Annual Gonadal Dose equivalent (AGDE) was less than global value 300μSv.y^-1 as recommended by UNSCEAR2008, Annual Effective Dose Equivalent (Eav.) was less than global value 260 μSv. y^-1 as recommended by UNSCEAR2000 and ELCR with an average value for four groups was less than (2.5*10^-3) recommended by ICRP and WHO [33] (Figure 3).

Figure 3: Comparison of excess lifetime cancer risk (elcr) for the four studied food types with global (UNSCEAR 2000)

From Table 7 and 8, was done, using ANOVA analysis, to calculate the mean, standard deviation, standard error, and the lowest and highest values for the four studied foodstuff, where the relationship among the four groups was statistically significant because the probability value was less than 0.05, while the relationship was statistically significant only between (wheat and corn), (pasta and corn), (rice, and corn), by using Tukey HSD test.

Tab. 7. Statistical comparison among the studied foodstuffs for AGED using the ANOVA test and between each two groups by Tukey HSD test

Tab. 8. The mean difference is significant at the 0.05 level.

Conclusion

A sensitive experimental approach for studying natural radioactivity and figuring o ut r adionuclide c oncentrations a nd dose rates in various samples of wheat flour, rice, pasta, and corn is the use of high-resolution-ray spectroscopy. Low values for radioactive concentrations of 226Ra, 232Th, and 40K were found in the samples examined for this study, which contributed to the low absorbed dose rates in the air. Also, the studied radiometric parameters AGDE, Eav and ELCR for each type of food were found to be within the permissible limits of health organizations. The current investigation of the radioactivity of four classes of foodstuffs is the fi rst of its ki nd at th e na tional level. It ha s been discovered that ingestion of this kind of food is safe in the groups examined. The relationship among the studied groups was statistically significant, that is, the p-value is less than 0.05, this may be due to the difference in the annual intake value among foodstuffs. Th e re search's co nclusions wi ll ai d in establishing a baseline of radiation exposure from food consumption for the (adults) general public.

Acknowledgements

Great gratitude and acclaim are due to the University of Kufa in Iraq for the resources and support it offers to researchers, particularly the lab in the College of Education for Girls' Physics Department, which allows for the completion of all sample measurements.

Ethical Approval

The study protocol was approved by local ethics committee.

Disclaimer

None

Conflict of Interest

There are no conflicts of interest to declare.

Funding Disclosure

Support by ourselves

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