Investigation of the effect of specific activity of 137Cs in the

Romanian Biotechnological Letters
Copyright © 2012 University of Bucharest
Vol. 17, No.2, 2012
Printed in Romania. All rights reserved
ORIGINAL PAPER
Investigation of the effect of specific activity of
cheese from mountain Golija
137
Cs in the production of
Received for publication, June 15, 2011
Accepted, May 20, 2012
MIHAJLO VIĆENTIJEVIĆ 1*, VUJADIN VUKOVIĆ1 DRAGAN ŽIVANOV2
1.
Institute of Veterinary Medicine of Serbia, Belgrade, Serbia
Faculty of Veterinary Medicine, Belgrade, Serbia
*Corresponding author: tel.+381 64 1194910
Fax: + 381 11 2673759
E-mail: [email protected]
2.
Abstract
The components of the field of gamma radiation are variables in function of time and location,
and it is necessary to disclose them and permanent monitoring at specific locations.
The importance of this work is that we had found the load of ionizing radiation on the
mountain Golija, which is expressed with intensity of gamma radiation dose exposure (SI units of
pC / kg.s). In addition, ionizing radiation implied emission of 137Cs and obtained values were
measured in the environment, i.e. air at the appropriate locations. The results represent the
average of the total of one hundred measurements for each location.
Within a certain number of households is also made detection of biologically significant
radionuclide 137Cs in the food chain, including water, soil, hay and silage, as well as transfer to
milk and cheese. The 137Cs activity concentration was expressed in Bq/kg.
Due to the strong specificity of obtained results statistical analysis was done by calculating
average values within the variation within each group (Xsr).
Key words: radioactivity, 137Cs, food chain, milk, cheese from mountain Golija
Introduction
The radiation load of the living world in a certain part of the territory, which is caused
by the effects of all forms of ionizing radiation in the environment, can be estimated using
radiation phon of biosphere [1]. It is therefore necessary to monitor and measure radio
ecological parameters of biosphere [2], for determination of so called Zero state at a defined
location on one or more measurement points.
In the last four decades occurred several nuclear disasters of which the breakdown of
peaceful nuclear plant in Chernobyl, 1986, represented a real radioactive disaster. On that
occasion almost all European countries were affected, more or less with the radioactive
contamination of the environment [3].
The occurrence of fallout, as well as various types of atmospheric residue especially
endangered grazing animals - milking cows (cows, sheep, goats) or animals in whose
nutrition is necessary green mass. It is well known that the biologically significant radio
nuclides (89,90Sr,134,137Cs, 131I, 103,l06Ru, etc.) after ingestion were very quickly eluted from the
body of animals [4]. For example, 131I occurs in milk in 3 to 6 hours after ingestion and
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Investigation of the effect of specific activity of 137Cs in the production of cheese from mountain Golija
similar situation is with the other radionuclide from a mixture of fission products [5]. In this
way, in milk and dairy products occur the residues of radioactive substances.
Radioactive isotope 137Cs was reached into environment by precipitation, after the
nuclear tests in the 60`s and after the nuclear disaster at Chernobyl 1986. Chemical similarity
to potassium explains its high mobility in biological systems. Because of its long half-life
(137Cs,T1/2 of 30 years) it must be monitored in all samples of the environment [6]. Thus,
transfer of Chernobyl cesium in the milk of cows in the various Nordic countries was
compared. Data were collected from agricultural and individual farms. 1986. and 1987.
greatest amounts of 137Cs were found in Finland and Norway, the average value in Sweden,
the Faroe Islands and Iceland, and the lowest values detected in Denmark. It is believed that
the Faroe Islands, Iceland and Norway were the most affected by the new disaster [7].
Resorption of radioactive cesium, from the digestive tract of animals, is significantly
reduced in animals that eat dry bulky feed. Also, the grazing nutrition causes a higher
radioactive contamination with radioactive cesium of dairy cows compared with the stable
nutrition, this is highly expressed in ruminants, particularly in sheep, because they are taking
parts that are close to the ground, resulting in entry of smaller amounts of land into body.
Cows which are grazing in highland area are much more contaminated with radioactive
cesium, compared with cattle that grazed in the plains: in the lowland area by 7 times, and
highland area for 30 times. Here, we should not lose out of sight the fact that is of the crucial
importance for the level of activity of radionuclide 137Cs: the amount of precipitation in the
highland area is 1.1 to 1.5 times higher than in lowland areas.
Distribution of radioactive cesium after a one-time entry into the body of cattle, sheep
and pigs is similar in all species approximate to distribution of potassium. However, the
biological elimination is highly different in the individual animal species and is significantly
greater in ruminants than in non ruminants. Biological elimination of the radionuclide 137Cs is
done with excretions (feces, urine) and secretions (milk) and during the first 7 days is 30 % in
feces and urine and 10 % in milk. Although the elimination of the radionuclide 137Cs over
milk is less studied than the elimination of radioactive strontium, it was known that the 10
times more cesium is excreted through the milk than strontium, which appears to be higher,
depending on the absorption of cesium from the digestive tract.
In daily ingestion of radionuclide 137Cs , during the long period, daily extracted milk
of dairy cows are containing about 10 % of the daily entered activities of this radionuclide,
which is an average of 1.4 % per liter of milk. In the daily ingestion of dairy cows with fresh
forages (clover) which had been radioactively contaminated with radioactive cesium - 134Cs
and 137Cs - at the time of acute radiation situations related to the Chernobyl in 1986, the
examination has shown that the level of activity of this radionuclide in the milk increases
during the first 5-7 days, after which it declined slightly and remained at the saturation level.
Almost identical results were obtained during the winter feeding of dairy cows with silage
contaminated by radioactive nuclides of cesium - 134Cs and 137Cs [8, 9, 10].
Control of fallout on a global scale, studies on the training grounds for the testing of
nuclear weapons and laboratory studies have suggested, and it is absolutely accepted, the
radioactive iodine (131I), radioactive strontium (89Sr and 90Sr) and radioactive cesium (137Cs)
released the highest doses. Over the last decade, there has been significant progress in
developing countermeasures for prevention or reduction of contamination of animal products
from radioisotopes of iodine, cesium and strontium [11].
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Materials and methods
In the standardization of production process for traditional production of cheese from
Golija mountain, the impact of radioactivity in production represents an important part of
research. Examinations were planned to include all parameters that contribute to obtaining the
final product- cheese from this mountain. It is presumed that the examinations are carried out
in the Golija mountain, in the selected area and selected households in spring 2009.
Measuring of gamma radiation exposure dose in the air
Visiting the mountain Golija, it was determined that the examinations will be perform
in the village Katići and at four location for measuring the intensity of gamma radiation dose
exposure
in
the
air.
For
measuring
we
used
the
alarm
monitor
of radiation MZ-100, and the obtained results, i.e. the values of exposure doses are expressed
in pC/kg.s.
The alarm monitor recorded hundreds of different results at every selected location,
which were presented in the form of average values. We got the mean value (Xsr) of intensity
of gamma radiation exposure dose in the air by comparing these values with all four locations.
Elevation of selected location is about 1,000 feet, and the names we have undertaken
locally are known as (Figure 1, 2, 3, 4):
1. Kurčubić elevation, 2. Bogdanović well, 3. Stanišić hill, 4. Obradović boarding house
Figure 1: Kurčubić elevation
Figure 2: Bogdanović well
Figure 3: - Stanišić hill
Figure 4: Obradović boarding house
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Investigation of the effect of specific activity of 137Cs in the production of cheese from mountain Golija
137
Cs activity concentration in food chain
The average values of intensity of gamma
exposure dose rate in the air (pC/kg.s)
1.
Kurčubić elevation
1,65
2.
Bogdanović well
1,62
3.
Stanišić hill
1,59
4.
Obradović boarding house
1,68
Xsr=1,64 (1,59-1,68)
In the village of Katići experiments have been set up to examine the 137Cs activity
concentration (Bq/kg) in the food chain of dairy cows and its transfer through the milk in the
finished product – cheese from Golija mountain.
The study involved six selected households, where the samples were collected from
the food chain: water, soil, hay, silage, milk, cheese. Households covered by examining are
known to the authors and in the paper are marked with numbers: 1, 2, 3, 4, 5, 6.
Water samples, which are used to supply the dairy cows were taken in plastic bottles
in quantities of 1 liter. Soil samples from which are prepare hay and silage for feeding dairy
cows and feeding animals are taken from three layers of different depths (0-5 cm, 5-10 cm
and 10-15 cm) and a metal blade in plastic bags in quantities of 1 kg. Also samples of hay and
silage, used for feeding milking animals, were taken from storage -place in plastic bags in
quantities of 1 kg.
Milk samples were collected as a bulk sample of milk obtained from dairy cows over a
particular host, the same goes for cheese samples. In addition, milk samples collected in
special plastic bottles volume of 1 liter, and samples of cheese in plastic bags in quantities of
1 kg. The above samples transferred to the hand fridge in the lab for testing.
Gamma spectrometry analysis and measuring the 137Cs activity concentration in the
food chain was performed on the detector of high purity germanium (HP Ge) with a
multichannel analyzer ("ORTEC``). Examinations were performed in laboratory conditions.
o.
Sites
Results and discussion
Intensity of gamma radiation exposure dose in the air were measured at four different
locations is shown only as an average value of one hundred consecutive measurements
(device MZ-100). These values ranged from 1.59 to 1.68 pC/kg.s or mean value for all
locations was 1.64 pC/kg.s (Table 1).
Table 1. The average values of intensity of gamma exposure dose rate in the air
Xsr: Mean
The obtained results are in accordance with findings of [12] amounts 1.63 to 1.81
pC/kg.s and they are obtained as a result of the constant monitoring of radiation background
on a permanent location in Belgrade.
Similar results are obtained in radioactivity monitoring of the environment [13] in
Serbia. Radiation-hygienic supervision over the HACCP system in the region of Golija
guarantees the radiation safety, by the resource status of the radio ecological aspects in the
production of healthy food. Our results are required to contribute to the further optimization
of the monitoring system to produced natural radioactivity, which is of special significance
for other forms of agricultural production (crop to livestock) [14].
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137
Cs activity concentration in water samples which is using for supply livestock
shows detection of all six samples and values ranged from 0.02 to 0.12 Bq/kg or Xsr = 0.05
Bq/kg (Table 2). In paper [15] 137Cs activity concentration in all samples in the river and
drinking waters in the territory of Serbia was on the limit of detection, which is in accordance
with our results. Similar results were shown [16] for a total of 22 analyzed samples of
drinking water. In some samples of tap water, especially those during the summer months,
detected traces of 137Cs, but the measured values are about 1,000 times less than the
legislation limits.
Furthermore, observing gamma spectrophotometric analysis and the value of 137Cs
activity concentration (Bq/kg) (Table 2), shows that in samples taken from all three depths of
the ground (0-5 cm, 5-10 cm to 10-15 cm), in all six households were detected 137Cs.
Thereby, in the shallowest layer of soil (0 to 5 cm) interval of variations of 137Cs
activity concentration ranged from 34.62 to 157.55 Bq/kg i.e. an average of 101.25 Bq/kg.
These values for medium deep layer of soil (5 to 10 cm) ranged from 13.57 to 185.40 Bq/kg
i.e. the mean value were lower than in the shallow layer amounted to 92.44 Bq/kg. The mean
value of 137Cs to the deepest layer (10-15 cm) was 84.18 (18.10 to 144.48 Bq/kg). It can be
seen that the obtained mean values decrease with increasing depth layer of soil from which
the sample was taken.
In the study area for monitoring the environment in Serbia they got the approximate
data [17].
Rinsing process and the relocation of 137Cs can lead to very unequal distribution of
radionuclide’s in one area so that on the basis of the results of numerous studies suggests that
migration of radionuclide’s in soil depends on many environmental factors, especially soil
properties such as physical and chemical properties (content of organic matter, adsorption
complex characteristics, pH, mineral compositions, etc.), the structure (mechanical
composition), water regime (water content, groundwater level), cultural practices (tillage,
fertilization), etc [18]. Also, at the mountain Stara Planina in the Bulgarian part of the
mountain, according to measurements from 2005. 137Cs activity concentration ranged in the
interval between 11 and 2543 Bq/kg. It was concluded that the adoption to migration of 137Cs
in soil is largely dependent on physicochemical characteristics of the land and the type of
vegetation. The wide variations of the measured specific activity are a consequence of the
variability of these parameters in the soils of the investigated area. [19].
Table 2. Specific activity of
137
Cs in the food chain
Values of
137
Sample type
Water
Ground 0-5cm
Ground 5-10cm
Ground 10-15cm
Hay
Silage
Milk
Cheese
1
<0,10
98,73
93,85
99,29
0,30
0,71
0,36
0,61
2
<0,10
34,62
29,92
26,42
0,19
0,16
0,05
<0,10
Cs activity concentration (Bq/kg)
Households
3
4
5
6
<0,10
0,12
<0,10
<0,10
140,82 157,55
84,51
91,26
185,40 175,38
56,53
13,57
144,25 144,48
72,52
18,10
1,14
1,87
0,31
0,62
0,31
0,55
0,26
0,14
0,68
0,31
0,06
0,16
0,10
0,15
0,68
0,71
Xsr
(Bq/kg)
<0,10
101,25
92,44
84,18
0,74
0,36
0,27
0,38
Xsr: Mean
Please replace , with . where you consider!!!
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137
Cs activity concentration have been studied on hay and silage which were used to
feed dairy cows at all six households, which are the final part of the food chain in the
production of milk and the final product – cheese from mountain Golija.
It was found that 137Cs was detected in the hay silage at all six samples and values
were an average of 0.74 (0.19 to 1.87) Bq/kg for hay, respectively, and 0.36 (0.14 to 0.71)
Bq/kg for silage (Table 2). It can be seen that both the mean do not exceed the limit of 1.0
Bq/kg.
Similar results have shown in [20] because the values of 137Cs activity concentration
obtained for feed does not exceed the prescribed level.
The degree of the presence of 137Cs is not the same in the all regions of Serbia, which
is, among other things, caused by unequal 137Cs activity in the precipitation in 1986. Thus, a
high 137Cs activity concentration in the soil reflected in the activity of radionuclide’s in the
hay. 137Cs activity in the hay from mountain Maljen were 32.4 Bq/kgs, while in Toplica
district the value was 8.1 Bq/kg. In the region of Uzice 137Cs activity concentration in the
precipitation was the highest, which led to its greater activity in the soil, human and animal
feed [21].
Table 2 shows the values of 137Cs activity concentration in the milk obtained from
cows used in the experiment. 137Cs was detected in all samples and these values for individual
households are ranged from 0.06 to 0.68 Bq/kg with a mean value of 0.27 Bq/kg.
Similar results were obtained in [23, 23] where 137Cs activity concentration were in the
range of measured phon. In [24] measured milk samples also have values higher than 1.0
Bq/kg. The results of veterinary-sanitary control [25] confirmed that the milk as a strategic
food were radiation-hygienic safe when importing.
The predictions model of 137Cs concentration in the cow’s milk, based on soil
properties and quantities of radioactive rains, was made in the England [26]. Transfer of
biologically significant radionuclide’s from plant foods, i.e. grass crops to milk, compared to
other foods of animal origin, is of particular interest, since the radionuclides of used plant
foods quickly pass in the milk [27]. The radiation load of milk by radioactive residues was
almost exclusively a result of transfer of radionuclide’s in the food chain, i.e. its segment soil
- plant - milk [28].
Similar results [29] were obtained in samples of cheese obtained from milk which
values of 137Cs activity concentration (Bq/kg) ranged from 0.03 to 0.71 Bq/kg or with a mean
of 0.38 Bq/kg (Table 2). In terms of the established level of 137Cs cheese represent safe food,
in terms of radiation-hygienic control, because the radioactivity in the cheese, as well as milk,
was within acceptable limits that are specific to these areas.
Conclusions
Based on the results obtained, we can conclude that the activities of natural and
artificial radionuclides in milk and dairy products varied in acceptable limits that are specific
to these areas, and in these core samples from the food chain of dairy cows, in order to
provide quality nutrition in terms of radiation-hygienic monitoring. Also, quantitatively
determined resource status Golija with radio ecological aspects.
Acknowledgments
These examinations carried out under research project No. 20111 of the Ministry of Science
and Technological Development of Serbia led by Professor Mihailo Ostojic, Professor of
Agriculture, University of Belgrade.
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