Natural Radioactivity and Radon Activity Concentrations in Canned Milk Samples in Iraq

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1 Natural Radioactivity and Radon Activity Concentrations in Canned Milk Samples in Iraq Ali A. Abojassim (1), Hussain H. Al-Gazaly (1), Suha H. Kadhim (1) and Michele Guida (2) (1) University of Kufa, Iraq/ Faculty of Science/ Department of Physics, PO box (221) Najaf, (2) University of Salerno and National Institute for Nuclear Physics (INFN), Italy/ Laboratory for Environmental Radioactivity, Department of Physics "E. R. Caianiello", Fisciano (SA), www. Abstract: - In this study aimed to put the basis for a baseline of concentration of investigations on the occurrence of natural and anthropogenic radioisotopes in Iraq, in thirteen canned samples of powdered milk, available in Iraq's markets, Radioactivity of the principal Naturally Occurring Radionuclides in anthropic and natural environments: 238 U( 226 Ra), 232 Th and 40 K, have been measured by means of gamma ray spectroscopy with a NaI(Tl) detector. Also, fifteen canned samples of the most common firms of liquid milk have been investigated for detecting the presence of Radon with an innovative measurement technique by means of alpha spectrometry of Radon short-lived progenies using the RAD7 Radon-in-air analyser. In the samples of powdered milk, the measured specific activities of 238 U( 226 Ra), 232 Th and 40 K range from 0.115±0.062 to ±1.067 (Bq/kg), from 0.562±0.065 to 2.930±0.807 (Bq/kg), and from ±2.984 to ±8.450 (Bq/kg), respectively; Also, it has been found that, for the same samples, the Radium Equivalent Activity and the Internal Hazard Index for the above radionuclides range from to (Bq/kg), from to 0.210, respectively. The average Total Effective Dose associated to the exposure due to annual intake of 238 U( 226 Ra), 232 Th and 40 K from ingestion of powdered milk, has been estimated to be for children μsvy - 1, μsvy -1 and μsvy -1, in the following age ranges (2-7y,7-12y and 12-17y ) while for adults (over 17y) has turned out to be μsvy -1, μsvy -1 and μsvy -1, for the three different species of radionuclides, respectively. All these results for the average specific activities and the Radiation Hazard Indices of 238 U( 226 Ra), 232 Th, 40 K, have been compared with the reference limits recommended by UNSCEAR and found to be below those values. For the samples of liquid milk Radon activity concentrations have been measured with the new proposed technique and the resulting values vary from 59.2±5.4 to 237.3±10.9 (mbq/l) turning out to be lower than the reference limits indicated by the World Health Organization and by the regulatory bodies of European Union. Key-Words: - Canned milk in Iraq, Iraq markets and NORM in food. 1 Introduction Radionuclides, both of anthropic (i.e., Cesium-137, Iodium-131 and Strontium-90) and natural origin (NORM; Naturally Occurring Radioactive Materials) (i.e., like the most radiologically relevant ones: Uranium-238, Thorium-232, Radium-226, Potassium-40, Radon-222, Polonium-210, Lead- 210), are enabled to enter human body mainly through inhalation of contaminated air and ingestion of contaminated water and food. Other pathways for radionuclide penetration into human body, like for example through the skin, are irrelevant for the context of this study. According to their different physico-chemical properties, they can accumulate in different tissues and organs of the human body and, thus, representing a serious health issues for exposed workers and population all over the world. In particular, their assumption through daily intake of food can turn out to be quite relevant to be taken in consideration. For example, chemical Uranium- 238 turns out to be toxic primarily for lungs and kidneys, where it causes damages to the proximal tubule, besides the fact that when in the metal form, it has also been identified as a potential reproductive toxicant [1]; Thorium-232 affects lungs, liver and skeleton tissues; Potassium accumulates in muscles [2] and Radium is retained primarily in bones, due to metabolic similarities with Calcium. Therefore, ISBN:

2 depositions of large quantities of these radionuclides in particular organs will be able to affect the health condition, through the weakening the immune system, inducing various types of diseases, and finally contributing to increasing the mortality rate [3]. Also, Radon being at STP (Standard conditions of Temperature and Pressure) a gaseous, chemically inert radioactive element resulting from Radium alpha decay and one of the heaviest gases, it is well known that can turn out to be extremely harmful to human health when people are exposed to it [4]. The major radioisotopes of radiological relevance are the primordial radionuclides related to the families of Uranium decays series, like Thorium, Radium, and Radon. Some of them can be ingested through the daily intake of food and water, while others, such as Radon, are mostly inhaled. However, Radon solubility in water is relatively low [5] and, with its short radioactive half-life of days, much of it will decay before it can be released from groundwater through degassing. Therefore, it is natural to find Radon in groundwater from deep wells, and as a result, if this water is used for drinking purpose, Radon can be uptaken by people and livestock [6]. Thus, if such radon-enriched waters are being used in the process of milk production, there is, also, a possibility that milk can be contaminated by this radioactive element [7]. Milk is an important vector of radionuclides that human beings may get from the environment through the mining activities [8]. Also, milk is one of the important food for the human nutrition and contains all the macronutrients namely protein, carbohydrates, fat, vitamins (A, D and B groups) and trace elements particularly calcium, phosphate, magnesium, zinc and selenium [9, 10]. In Iraq no surveys of Natural Radioactivity in milk have been carried out and so far no baselines of concentration of natural and anthropogenic radioisotopes have been reported. Therefore, the monitoring of radioisotope activity concentrations will provide meaningful information that can contribute to the knowledge of population exposure and to the setting up of original baseline [10]. This work has been undertaken with the purpose of measuring Natural Radioactivity to 238 U( 226 Ra), 232 Th and 40 K in powdered milk samples and 222 Rn activity concentrations in liquid milk samples that are available in the Iraqi markets. Also in this study Radium Equivalent Activity, Internal Hazard, the Absorbed Dose Rates and annual Effective Dose for 238 U ( 226 Ra), 232 Th and 40 K to human beings in different ages have been calculated depending on standard world equations, so as to compare them with the recommended reference limits. 2 Materials and Methods Thirteen samples of different types of powdered milk for infants have been collected from the local markets in Iraq to measure Natural Radioactivity, while fifteen samples of different types of liquid milk to measure Radon activity concentrations. The two typologies of milk samples are listed in Tab. 1 and Tab. 2, respectively. Natural Radioactivity levels have been measured using a gamma spectrometry facility, consisting of a gamma multichannel analyzer equipped with a (3" 3") NaI(Tl), Figure 1. (a) (b) Figure 1: (a) Experimental set-up, (b) set-up block diagram Table 1: Types and origins of the powdered milk samples No. H.V Sample code Pre.Amp Sample name Country of Origin 1 M1 DIALAC VIETNAM 2 M2 AL-MUDHISH Amp MCA Interface PC SULTANATE OMAN ISBN:

3 3 M3 ALMA NEW ZEALAND LABAN 4 M4 MILMO POLAND 15 ML15 PEGAH BANANA IRAN 5 M5 NOVALAC GERMANY 6 M6 RAYOOK JORDEN 7 M7 AL-MUNAISH AL EMARAT 8 M8 FATIMA IRLAND 9 M9 FRESH IRAN 10 M10 BABY GONUIOR FRANCE 11 M11 CARNATION DUBAI 12 M12 RAINBOW SULTANATE OMAN 13 M13 NIDO DUBAI No. Table 2: Types and origins of the liquid milk samples Sample code Sample Name Country of Origin 1 ML1 ALTAG LABAN IRAQ 2 ML2 AL SAFI MILK KSA 3 ML3 NADA MILK KSA 4 ML4 ALMARAI MILK KSA 5 ML5 6 ML6 7 ML7 NADA STRAWBERRY ALSAFI BANANA ALSAFI CHOCOLATE KSA TURKEY TURKEY 8 ML8 KDD MILK KUWAIT 9 ML9 ALRAAI CHOCOLATE KUWAIT 10 ML10 MANIZAN LABAN IRAN 11 ML11 KALLEAH MILK IRAN 12 ML12 PEGAH MILK IRAN 13 ML13 PEGAH LABAN DOG IRAN 14 ML14 KALLEAH SEVEN IRAN The gamma spectra have been analyzed using the ORTEC Maestro-32 data acquisition and analysis system. The detector has a coaxial closed-facing geometry with the following specifications: the calculated resolution is 7.9% for energy of kev of a 137 Cs standard source. Relative efficiency at 1.33 MeV for 60 Co was 2.2% and at MeV for 22 Na was 2.4%. The detector has been shielded by a cylindrical lead shield in order to achieve the lowest background level. An energy calibration for this detector has been performed with a set of standard γ-ray 1-μCi active 137 Cs, 60 Co, 54 Mn, and 22 Na sources. In this study, the activity concentration of 40 K has been determined directly from the peak areas at 1460 kev. The Activity concentrations of 238 U( 226 Ra) and 232 Th have been calculated assuming secular equilibrium with their decay products. The gamma transition lines of 214 Bi (1765 kev) have been used to calculate the specific activity of the radioisotopes in the 238 U-series, while for the 232 Th-series the specific activities have been determined using gamma transition lines of 208 Tl (2614 kev). The counting time for each sample has been of about s. Since the counting rate is proportional to the amount of radioactivity contained in a sample, the Activity Concentration, or Specific Activity, A x, can be evaluated in the following way [11,12]: (1) where C is the area under the photo-peaks, ε% the present of energy efficiency, I γ the present of gamma-emission probability of radionuclide X under consideration, t the counting time, M the mass of sample and BG the background. 2.1 Radium Equivalent Activity The most common Naturally Occurring Radioisotopes that can be found in foodstuff are represented by 232 Th, 40 K and 238 U( 226 Ra). In order to assess the gamma radiation doses to human beings due to the (internal or external) exposure to them, it is necessary to evaluate how to take properly into account their specific radioactivity. To this purpose a suitable and practical index, the so-called Radium Equivalent Activity index Ra eq has been introduced by E. I. Hamilton from the UK National Radiological Protection Board (NRPB) [13]. Ra eq has been defined on the basis of the preliminary ISBN:

4 estimation of the quantities of these radionuclides releasing the same gamma ray dose. From the extensive review of the investigations, performed in different countries, realized by a group of experts from the Organization for Economic Co-operation and Development (OECD) s Nuclear Energy Agency [14] it turns out that a general agreement can be found on the statement that 370 Bq/kg (10 pci/g) of 226 Ra, or 260 Bq/kg (7 pci/g) of 232 Th or 4810 Bq/kg (130 pci/g) of 40 K provide the same gamma ray doses [15 18]. Consequently, the following Radium Equivalent Activity (Ra eq ) of a sample in (Bq/kg) can be evaluated as [18-22]:..(2) where A Ra is the specific activity of 226 Ra, which is usually the same as that of 238 U( 226 Ra), in (Bq/kg), A Th is the specific activity of 232 Th, in (Bq/kg), and A K the specific activity of 40 K, in (Bq/kg). This equation is based on the estimation that 10 Bq/kg of 226 Ra equal 7 Bq/kg of 232 Th and 130 Bq/kg of 40 K produce equal gamma dose. The maximum value of Ra eq must be less than 370 Bq/kg [15]. 2.2 Internal Hazard Index individuals and is determined by ICRP (1995) [21]. The average consumption rate of milk for children, in different age groups (age from 2 to 7 y, 7 to12 y and from 12 to 17 y), and adults ( from 17 y) is 14Kg/y and 13Kg/y, respectively [26, 27]. 2.3 Radon activity concentrations measurements in liquid milk samples Radon Activity concentrations in liquid milk of samples have been measured with the Radon-in-air analyzer RAD7 (DURRIDGE Company, Inc. - Bedford, MA, U.S.A.) [28], capable to perform Radon short-lived progenies (Polonium-218 and Polonium-214) alpha spectrometry from the air stream maintained through the system with an internal pump. For these measurements, the RAD7 has been equipped with the accessory kit for sampling measurements in water, RADH20, [29], enabling it to measure Radon-in-water, over a wide activity concentration range, from 3.7 mbq/l (Detection Limit) up to much greater values than 3 kbq/l [30], with an accurate reading achieved in 30 minutes acquisition data runs, Fig. 2. In the international scientific community there is a general consensus that regarding the human internal exposure, due ingestion or inhalation, the introduction of a specific so-called Internal Hazard Index turns out to be very suitable to assess the radiation hazard. The Internal Hazard iindex (H in ) is given by the following expression [18, 24, 25]:..(3) a consequence radiation hazard can be considered negligible if H in turns out to be smaller than one. 2.3 Annual effective dose The annual effective dose due to the intake of 238 U( 226 Ra), 233 Th and 40 K in foods can be calculated using the formula from UNSCEAR (2000) [17]:.(4) where D is the annual effective dose (Sv/y), C is the specific activity of radionuclides in the ingested sample (Bq/Kg), I is the annual intake of powdered milk (Kg/y) which depends on a given age [21] and E is the ingested dose conversion factor for radionuclides (Sv/Bq). The conversion factor E varies with both radioisotopes and the ages of the Figure 2. Schematic representation of the RAD-7 experimental set-up for measuring Radon-in-Water Activity concentrations [28, 29]. The experimental procedure is the same as the standard one for measuring Radon-in-water [31] with the only difference that the density of milk is higher than density of water. Therefore, the standard experimental set-up has been modified, including a bigger vial containing the sample (2.5 liters, instead the standard 250 ml) and also tubing and connecting accessories have been replaces such that to prevent the entry of the milk bubbles inside the RAD7 detector. ISBN:

5 3 Results and Discussion 3.1 Natural radioactivity in powdered milk samples The measured specific activities of 238 U( 226 Ra), 232 Th and 40 K detected in the samples of powdered milk under study including their uncertainty are summarized in Table 3. It can be noticed that the 238 U( 226 Ra) activity concentrations detected in most of samples vary between (0.115±0.062) Bq/kg to (25.000±1.067) Bq/kg with an average value of (15.274±8.241) Bq/kg. For 232 Th and 40 K the measured specific activity ranged from (0.562±0.065) Bq/kg to (2.930±0.807) Bq/kg with an average value of (1.620± 0.643) Bq/kg and from ( ±2.984) Bq/kg to ( ±8.450) Bq/kg with an average value of ( ± ) Bq/kg, respectively. Also, the values of radiation hazard expressed by Ra eq and H in have been found to range from (08.021) to (54.753) Bq/kg with an average of (34.103±15.737) Bq/kg and from (0.021) to (0.210) with an average value of (0.1183±0.0668) respectively (Table 4). The average value of the Annual Effective Dose for children in the different age groups: (2-7)y, (7-12)y, (12-17)y and for adults (age over 17 y) due to the intake for the three different radionuclides has resulted to be: for 238 U( 226 Ra): µsv/y, µsv/y, µsv/y and µsv/y; for 232 Th µsv/y, µsv/y, µsv/y and µsv/y; for 40 K µsv/y, µsv/y, µsv/y and µSv/y (Table 5). Table 3: Specific Activity (Bq/kg) in powdered milk samples M ± ± ±7.352 M ± ± ±8.845 M9 BDL BDL ±4.124 M10 BDL BDL ±3.213 M11 BDL BDL ±2.984 Average ± S.D ± ± ± Table 4: Radiation hazard in powdered milk samples (BDL = Below Detection Limit) Sample Code Raeq (Bq/kg) Internal Hazard Index M M M M M M M M M Sample Code U-238 (Ra- 226) Specific Activity (Bq/kg) Th-232 K-40 M M Average ± S.D ± ± M ± ± ±8.983 M ± ± ±6.543 M ± ± ±8.126 M ± ± ±7.359 M5 BDL BDL ±6.598 M ± ± ±8.450 Table 5. Average Annual Effective Dose 238 U ( 226 Ra), 232 Th and 40 K for children in the age groups (2-7y), (12-17y) and adults (over17y). Age Group Annual Effective Dose (µsv/y) 238 U( 226 Ra) 232 Th 40 K Children (2-7) y ISBN:

6 Children (7-12) y Children (12-17) y Adults (over 17y) These results have been compared with the outcomes of different investigations performed in other countries. The comparison is shown in Table 6. Table 6: Comparison of the average specific activities (Bq/kg) of 238 U ( 226 Ra), 232 Th and 40 K in powdered milk with data published in other countries (where the average values is missing the range of values is indicated) Region 226 Ra 232 Th 40 K Referen ce Brazil ±9.9 [33] Egypt 0.44± France 0.05± German y 0.064± ± ± ± ± ±18. 3 [34] [32] [32] India [38] Iran ±3.3 [24] Jordan New Zealand [27] [32] Syria [35] Saudi - Arabia Saudi Arabia Venezue la Present Work ±1.9 [36] [37] U ( 226 Ra) ± ± ± ± [32] The results obtained show that for 238 U ( 226 Ra) the average measured specific activities and and their average value appears to above the values reported in other countries; for 232 Th some values are greater and others lower. But for this two radioisotopes the results measured in Iraq turn out to be lower than the recommended reference limits by UNSCEAR (2000) [17]: 32 Bq/kg and 45 Bq/kg) respectively. For what it concerns the specific activity of 40 K the comparison with other outcomes shows the same behavior like for 232 Th, but, nevertheless, the results from this study have been found to be lower than the recommended reference limit by UNSCEAR (2000): 412 Bq/kg [17] with the only exceptions of samples M1 and M6. Because Potassium is a macronutrient indispensible to plants, this fact could be attributed, after a preliminary evaluation, to a local higher concentration of Potassium and hence, 40 K, in plants consumed by livestock in Iraq. Radium Equivalent Activities and Internal Hazard Index (H in ) values for all the samples are below the recommended value of 370 Bq/kg and one, respectively [17]. Also, it is found that the Average Annual Effective dose from natural radioactivity turn out to be below the reference value of 1.0 msv/y recommended by ICRP for all ages [21]. 3.2 Radon activity concentration in liquid milk samples The measured radon concentrations in the samples of liquid milk under study including their uncertainty are summarized in Table 7. It can be noticed that 222 Rn detected in most of samples varied between (59.2±5.44) mbq/l to (237.33±10.89) mbq/l with an average value of (150.78±59.03) mbq/l. Since milk is mostly composed of water, (87%) [39, 40], probably Radon occurrence in the drinkable water consumed livestock could be the main cause of its presence in milk. Results of the average radon activity concentration in liquid milk samples turn out to be lower than the accordable limit as reported in WHO: 0.5 Bq/l [41]and the reference limit prescribed by European Union Commission: 1 Bq/l. [42] Table 7: Radon Activity Concentrations in liquid milk samples ISBN:

7 Sample Code ML1 4 Conclusion Natural radioactivity and Radon activity concentrations for the most available powdered and liquid milk brands consumed in Iraqi markets have been determined by using gamma spectroscopy and RAD7 technique, respectively. 238 U( 226 Ra) and 232 Th activities have been found below the prescribed international reference levels, while some samples have 40 K value which, however, have been found to be within the world wide ranges as reported in the international scientific literature. In addition the radon activity concentrations in liquid milk (considered as water) have been found lower than the corresponding values for Radon in water recommended by the WHO reference level [41] and the EU reference level [42]. References: Radon Activity Concentrations (mbq/l) BDL ML ±7.69 ML ±7.30 ML ±10.89 ML5 BDL ML6 59.2±5.44 ML7 BDL ML ±8.07 ML9 BDL ML ±9.74 ML ±8.78 ML ±9.74 ML ±10.59 ML ±5.96 ML15 178±9.43 Average±S.D ±59.03 [1] Linares V., Bellés M., Albina M. L., Sirvent J. J., Sánchez, D. J. and Domingo J. L. (2005). Assessment of the pro-oxidant activity of uranium in kidney and testis of rats, Toxicology Letters, 167, pp [2] Abollino O., Aceto M., Bruzzoniti M.C., Mentasti E., Sarzanini, C. (1998). Speciation of copper and manganese in milk by solid-phase extraction/inductively coupled plasma-atomic emission spectrometry Annals Chim. Acta, 375, (1998). [3] Tawalbeh, A. A., Samat, S. B., Yasir,M. S. and Omar, M. (2012). Radiological impact of drinks intakes of naturally occurring radionuclides on adults of central zone of Malaysia, Malaysian Journal of Analytical Sciences, 16(2), [4] WHO. (2009). WHO HANDBOOK ON INDOOR RADON A PUBLIC HEALTH PERSPECTIVE, WHO [5] Nazaroff W. W., Nero A. V. (eds.) (1988). Radon and Its Decay Products in Indoor Air, Wiley-Interscience (1988). [6] Ali A. Abojassim, (2013). Radon Concentrations Measurement for Drinking Water in Kufa City /Iraq Using Active Detecting Method. Advances in Physics Theories and Applications Vol.26, 2013, [7] Lindell B. (1968). Ingested radon as a source of human radiation exposure. Proceedings of International Congress on Radiation Protection, Rome. [8] IAEA, (1989). International Atomic Energy Agency, Measurement of Radionuclides in Food and the Environment, A Guidebook, International atomic energy agency, VIENNA, [9] UNSCEAR, (1982). Ionizing Radiation: Sources, and Biological Effect United Nations Scientific Committee on the Effect of Atomic Radiation., United Nations: New York, [10] FAO, (1999).The Impact Population Growth and Urbanization on Food Consumption Patterns in Jordan.UN, N. Y. [11] Beretka J. and Mathew P., (1985). Health Phys., 1985, 48,pp [12] Kumar A., Singh B. and Singh S., (2003). Radiation Measurements, 2003, 36(1-6),pp ISBN:

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