Assessment of natural radioactivity levels and annual equivalent doses in some milk powdered samples for adults used in Baghdad

In this paper the specific activity of 238U, 232Th and 40Kradionuclides were determined by sodium iodide enhanced bythallium NaI(Tl) detector and assessment the annual effective dosein samples of powder milk from different companies such asAlmunaish, Seven Caw, Molty and Altunsa for adult available inBaghdad markets. The specific activity of 40K has the greater value inall the samples which is in the range of allowed levels globally thatsuggested by UNSCEAR. The mean value of annual effective doseswere 0.121, 0.314775 and 0.305 mSv/y for 238U, 232Th and 40Krespectively.


Introduction
The purpose of the measurements of radiation in food and the environment is of principal importance in the prevention of radiation in order to protect humans from contaminated food and polluted environment as a result of nuclear activities [1], and thus protected food and the environment and appropriate non-contaminated with radioactive materials as a result of the disposal of these materials operations both during the process of nuclear activity or after it ends [2], thus identification and appropriate disclosure of the existence and nature of the radioactive material in food or environmental goals to take preventive measures or appropriate treatment through knowledge paths of radioactive material from the source until they reach the food or the environment [3,4]. The measurements of radiation in food and the environment, it is always advisable to be the amount of pollution in the food measure on the basis of measuring the amount of pollution in the different varieties of food each separately and based on the consumption pattern of these items where the process of analysis of the amount of the overview of the impact of the consumption of these types of radioactive materials, as well as to familiarity with the style of the production of these food items and the environment that produces it, and this includes familiarity with complementary operations of the production process or direct preparation before consumption [5,6]. Food varieties such as milk, meat, grains, fruits, vegetables and others may be exposed to contamination with radioactive material process within the food chain start-up of the plant and soil until the final consumption and to find out how much of this pollution [7], it must be sampling of these items in addition to the samples of soil, water and air, for example milk substance and that is consumed on a large scale has been contaminated as a result of animal ureter grazing of herbs that have been polluted, directly as a result of loss of radioactive material directly or through its transition from the soil as a result of loss deposited in the depths or through contaminated breathing air or drinking contaminated water hence become the need to deal with more than a source of samples to be measured and analyzed to see how much the concentration of radioactive material in them [8,9]. The aim of current work is measuring specific activity for 238 U, 232 Th and 40 K in samples of powdered milk; Almunaish, Seven Caw, Molty and Altunsa in the local markets of Baghdad city in 2014 and the calculation of the annual effective dose resulting from the presence of these radioactive isotopes using a gamma spectrometry, NaI (Tl) detector, this work is necessary in the viewpoint radiation protection and the search for the presence of natural radioactive elements in food covered by the humans.

Experimental part
In this paper samples: Almunaish, Seven Caw, Molty and Altunsa for adults available in Baghdad markets were prepared in 1kg for each sample. Techniques that used to determine NORM in milk powdered samples, gamma spectroscopy with sodium iodide (NaI(Tl)) detector which are calibrated for a period of 3600 seconds, and completely isolated by lead shield [10].

Radiation weighting factor
The absorbed dose in tissue or organ in the relative biological effectiveness of radiation in causing indiscriminate effects at low doses is called equivalent dose. The radiation weighting factor for photons equal to 1 [11]. The annual intake Int. (Bq. y -1 ) from taking milk for adult consuming 200 gm/day is considered by equation [11];

Results and discussion
Specific activity of uranium-238 series, thorium -232 and potassium -40 in samples of powdered milk for adult are listed in Table 1.  The annual effective dose AED in mSv/y were calculated by Eq. (2) and listed in Table 2.

Conclusion
Specific activity for 226 Ra, 232 Th and 40 K in different samples of powdered milk were measured by NaI(Tl) detector. The average value of specific activity for radionuclide 40 K was highest in all samples. The annual effective dose that accumulated from all isotopes were in the allowed levels globally.