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Determination of radionuclides in samples of middle-aged and older human femurs
Journal of Environmental Radioactivity 143 (2015) 85e90
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Journal of Environmental Radioactivity journal homepage: www.elsevier.com/locate/jenvrad
Determination of radionuclides in samples of middle-aged and older human femurs ski a, *, M. Solecki c J. Solecki a, M. Misztal b, S. Skupin a
Maria Curie Skłodowska University, Faculty of Chemistry, Department of Radiochemistry and Colloid Chemistry, Pl. M. Curie-Skłodowskiej 2, 20-031 Lublin, Poland b Department of Trauma Surgery and Emergency Medicine, Medical University of Lublin, Staszica 16, 20 081 Lublin, Poland c 2nd Department of General Surgery, Medical University of Lublin, Staszica 16, 20 081 Lublin, Poland
a r t i c l e i n f o
a b s t r a c t
Article history: Received 8 September 2014 Received in revised form 3 December 2014 Accepted 4 January 2015 Available online 6 March 2015
The paper presents the studies of the presence of gamma isotopes and 90Sr in 19 middle-to old-aged human femur samples. The samples were taken up during routine orthopedic operations in 2012. The aim of the paper was determination of some radionuclides in human bones and estimation of radiation dose created by 90Sr and 90Y (in bones). The 137Cs, 40K, 226Ra, 228Th, 234Th and 210Pb isotopes were determined by gamma spectrometry. The above mentioned radionuclide contents were in the ranges: 137 Cs (0.04e1.45); 40K (13e86); 226Ra (1e21.5); 228Th (1.4e40.2); 234Th (0.4e5.7); 210Pb (0.7e8.4) Bq/kg d.w. 90Sr was assayed based on radiometric measurement of ingrown 90Y. The 90Sr content was in the range 0.27e1.85 Bq/kg d.w. Measurements of concentration of 90Sr and 90Y in bones were used to estimation of health risk by calculation of radiation dose. Adsorbed doses ranged from 2.7$ 107 to 1.9 $ 106 Gy/y for 90Sr and from 1.2 $ 106 to 8.3 $ 107 Gy/y for 90Y. © 2015 Elsevier Ltd. All rights reserved.
Keywords: Radionuclides Human femur Bones Radiostrontium Radioelements
1. Introduction
CLOR, srodowiska i z_ ywnosci w Polsce w 1999 roku, 2000; PIOS _ 1998; Zarnowiecki, 1988).
The use of a nuclear bomb in 1945 (Hiroshima, Nagasaki) and then intensification of nuclear weapon tests (there were registered 50 nuclear explosions from 10.07.1945 to 31.12.1953) made the public aware of the danger resulting from uncontrolled radioisotope releases. Another sources are from deficiencies in structure and functioning of some reactors and the inconsiderate behavior of their users. These sources resulted in the appearance in the natural environment of, among others, long lived anthropogenic isotopes such as 137Cs 90Sr, 241Am, 238Pu, 239Pu, 240Pu and 241Pu. Considering the half-life (T1/2), it is assumed that the long-lived radionuclides 137 Cs, 90Sr and Pu contribute to the natural environment contamination to the largest extent. Therefore these isotopes should be systematically analysed. Such activities are carried out by some state institutions which publish their results in the form of reports ski, 1975; Nadzo r radiologiczny e.g (Grabowski et al., 1999; Kwapulin srodowiska e PTJ, s. Ochrona przed promieniowaniem, 1970; Roczniki rcze Statystyczne Ochrona Srodowiska, n.d.; Skaz_ enia promieniotwo
Based on the reports by Monetti (1996), and UKAEA (DATE NEEDED) the highest contamination with radiostrontium was found in 1958e1963 which is consistent with the literature data ski, 1994). about the Polish region (Siemin Moreover, as a result of Chernobyl Nuclear Power Station failure there appeared on the European territory the isotopes of the total activity 1.25 1019 Bq including 6.5 1018 Bq of noble gases, 8.14$1015 Bq of 90Sr and from 8.14$1016 to 9.25$1016 Bq of 89Sr; from 1.85$1016 to 4.44$1016 Bq of 134Cs and from 3.70$1016 to 8.51$1016 Bq of 137Cs (IAEA, 2001). Such large amounts of radionuclides introduced into the natural environment require permanent monitoring. 90Sr was recognized as the second after 14C as dangerous from the dosimetric point of view (Lieser, 2008). Harmfulness of 90Sr for living organisms is much higher than that of 137Cs due to emission of two beta particles of total energy higher than gamma quantum, good availability especially in bones (90Sr z Ca replacement of calcium and also long time of incomplete removal e biological half-period). There are a few reports about the presence of radionuclides in bones of animals, birds and people (Froidevaux et al., 2006, 2002; Komosa et al., 2009; Landstetter and Wallner, 2006; Mietelski et al., 2011, 2001; Stamoulis et al., 1999; Tandon et al., 1998;
* Corresponding author. ski). E-mail address: [email protected] (S. Skupin http://dx.doi.org/10.1016/j.jenvrad.2015.01.021 0265-931X/© 2015 Elsevier Ltd. All rights reserved.
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Table 1 Characteristics of studied femur samples. No Gender Age Discase (years)
Sample Sample mass after Ash mass after mass [g] drying [g] d.w. combustion [g]
5 1 9 2 16 4 8 11 15 12 19 10 14 3 6 18 13 17 7
43.0 36.5 39.8 17.7 45.9 33.7 45.2 23.7 25.6 38.2 50.8 19.3 31.1 19.2 19.3 21.5 18.3 23.0 19.8
F F M F M F F F F M M F F F F F F F F
56 62 68 69 71 77 77 77 79 80 82 82 83 84 88 88 90 95 97
os os os fracture os os os fracture fracture fracture os fracture os fracture fracture fracture fracture fracture fracture
39.4 34.1 36.5 16.7 43.1 31.3 41.1 21.5 24.2 35.4 18.2 47.5 29.0 17.4 17.8 20.4 16.5 21.7 18.6
18.2 16.1 18.8 4.9 20.8 14.1 19.1 9.2 8.8 15.3 7.2 22.3 13.2 6.7 6.4 7.3 5.4 8.1 7.1
2. Experimental
F e female, M men, os e osteoporosis and osteoarthrosis.
Table 2 Results of
90
Sr determination in the reference materials.
Name of sample
Reference activity, confidence range [Bq/kg]
IAEAeSOILe6, average from 4 measurements IAEAe375, average from 3 measurements flour I (PAA) flour II (PAA) Word-wide open proficiency test IAEA e CO-2007-03 Spinach IAEA-30
30.34 (24.20e31.67)
MDA value Activity determined and calculated on the [Bq/kg] reference date [Bq/kg] 34.8 ± 4.3
0.02
108 (101e114)
104.2 ± 23.9
0.02
0.15 ± 0.05 0.48 ± 0.01 20.1 ± 2.1
0.18 ± 0.03 0.47 ± 0.03 20.89 ± 1.38
0.01 0.01 0.02
(1998). It discussed the problems connected with the presence of some trace elements in bones and analytical difficulties caused by material specification, its complex character and variety as well as verification of results. Taking into account the above quoted literature reports, the attempt was made to apply the information about uptake and preparation of samples as well as determination methods.
Bone samples (femoral heads) were acquired during routine total hip arthroplasty. The project has been approved by Bioethical Council of Medical University of Lublin. Samples were taken from anonymous patients during surgical operations. After surgeries the bones were cleaned of any soft tissues, washed with saline and each frozen in a separate containers. Then all samples were collected, bones were defrosted and underwent physical examination (weight, volume etc). Each head was then divided into smaller pieces with a chisel and separately suspended the excessive amount of Benzinum Purum to flush the fat. Sample symbols and their characterization are shown in Table 1. Then the samples were taken from Benzinum Purum, placed on a Perti pan and dried at 60 C for 24 h. Next they were weighed, disintegrated using a hydraulic press, again put on the pans and dried to constant mass at 105 C for 24 h. The dried bones were moved quantitatively into porcelain beakers and after covering them with quartz glasses placed in the high temperature oven with automatic temperature regulation. The combustion process proceeded as follows: after reaching the temperature 200 C for 10 hours, the oven was heated for another 10 hours, the temperature was increased up to 400 C for 3 hours, and heated for 6 hours, the temperature was increased to 600 C for 3 hours and heated for 10 hours.
Wallova et al., 2012). Such research is particularly difficult because of necessity of obtaining samples, especially difficult for human bones, and the structure and composition of bone itself. One of the significant papers on bone analysis is the review by Tandon et al.
After cooling the ash was examined with respect to colour. In all cases it was gray powder which indicates proper mineralization without carbon formation. The samples were weighed to determine the ash mass (Table 1). The whole amount of ash was moved quantitatively to flat polyethylene boxes of thin walls. An aliquot of 0.2 g was taken and after the addition of 7.8 g of a flux, it was melted in a platinum
Table 3 Radioactive concentration of determined gamma radionuclides in human femur. No
Age (years)
137
5 1 9 2 16 4 8 11 15 12 19 10 14 3 6 18 13 17 7
56 62 68 69 71 77 77 77 79 80 82 82 83 84 88 88 90 95 97
0.58 ± 0.39 0.14 ± 0.09 0.60 ± 0.49
Cs [Bq/kg d.w.]
40
226
2.5 ± 2.8 3.9 ± 3.5
K [Bq/kg d.w.]
Ra [Bq/kg d.w.]
228
Th [Bq/kg d.w.]
234
Th [Bq/kg d.w.]
3.9 ± 4.9 4.9 ± 13.1 5.4 ± 9.9 2.6 ± 3.6
210
Pb [Bq/kg d.w.]
0.7 ± 4.4 2.7 ± 5.3 4.1 ± 4.7 1.5 ± 1.7 2.8 ± 3.4 1.0 ± 6.3 5.2 ± 4.6
J. Solecki et al. / Journal of Environmental Radioactivity 143 (2015) 85e90
87
crucible to obtain the samples for determination of metal cations including Ca and Sr by means of the WD-XRF method. The other part was weighed and measured in preparation for gamma spectrometry. The spectrometer produced by Silena had a germanium detector IGCe13 (Princeton GammaeTech) cooled with liquid nitrogen with 4096 channel amplitude analyzer. The detector capacity on the 60Co (1.33 MeV) was 15%. The gamma spectra were
subjected to measurements were placed in plastic boxes of the size to the type of the source used during calibration. After the gamma spectrometry, the samples were quantitatively moved to 250 cm3 beakers and weighed again. The whole amount of ash was used for 90Sr determination. The methods were based on evolution of 90Y, the product of strontium decay. The analysis was made according to the scheme:
analyzed by means of the computer program GENIE 2000. As the calibration model a standard source was used as prepared by the Central Laboratory of Radiological Protection (Poland) with the symbol SZN http://www.clor.waw.pl. The source was of disk shape, 3 mm high and 49 mm diameter made on the basis of polymer of about 1 g/cm3 density. The samples
Methods of 90Sr determination based on ingrowth and radiometric measurements of 90Y radioactive (secular) equilibrium allow to trace radiochemical purity (measurement of background after 90 Y decay) on one hand and to repeat the analysis of the same sample after equilibrium re-establishment (minimum 14 days) in the primary sample, on the other hand.
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For radiometric measurements there was applied a low-boiler counter LSC Quantulus 1220 e Wallac Perkin Elmer with computer programs for communication with the instrument and collection of the data WinQ as well as interpretation of radioactive spectra Easy View. The yield of counting was 100% in carbon channels. The measurement was performed for 300 min. The counting rate was registered in cpm. The data registered on the spectra of 90Y in the channels from 350 to 850 were taken in calculations. The determination method was tested using the reference materials and in the interlaboratory measurements. The results are presented in Table 2. The results of 90Sr determination (particularly for spinach samples) presented in Table 2 show that the proposed method obtained correct data. However, it should be noticed that bones belong to the samples of differentiated matrices as pointed out by Tandon et al. (1998), therefore preparation of reference material for such samples is very difficult. The reference samples proposed by MAEA, as a rule, contain many times higher concentrations of radionulcides than their contents determined in the samples. The samples of e.g. soil, flour, water prepared by the Institute of Chemistry and Nuclear Technique in Warsaw commissioned by the State Atomistic Agency (PAA) within the interlaboratory tests include the concentrations of radionuclides close to the level of their contents in environmental samples e.g. flour in Table 2. Determination of a given radionuclide in this type of samples makes the proposed method more reliable.
3. Results and discussion As can be seen in Table 3 the contents of radionuclides were in the ranges: 137Cs (0.04e1.45); 40K (13e86); 226Ra (1e21.5); 228Th (1.4e40.2); 234Th (0.4e5.7); 210Pb (0.7e8.4) Bq/kg d.w. Generally, it can be accepted that concentration of these radioelements increases with the person's age. The presence in bones of 137Cs is the evidence for its occurrence in food products (Solecki and Kruk, 2011) e.g. 0.3e0.9 Bq/dm3 in milk and in atmospheric air <0.1e5.4 mBq/m3 was found (“http://www.paa.gov.pl/,” n.d.). Cesium radionuclide half-period of effective biological removal is 60 days (Lieser, 2008), so with the practical disappearance of the world fall-out, its occurrence in bones can be due to the failure of Nuclear Power Station in Chernobyl.
Table 4 Concentration of
90
Table 4 presents the results of 90Sr determination in the bone samples. The methods allowed to make a few measurements from one sample. Column III in the Table 4 presents the results of 90Sr determination for the primary sample that is after dissolution of ash in HNO3, separation of 90Y and measurement of its activity. According to the procedure presented in the experimental part, after separation of 90Y, the solution still containing 90Sr was left for 14 days in order to establish equilibrium between 90Sre90Y. Then there was made repeated determination of 90Sr by removing 90Y from the primary sample. The results of the second determination are given in column IV in Table 4. This analytical procedure allows calculation of average values which improve determination reliability as follows from the data in Table 4, presentation of the results from one measurement, which in the case of bone sample (particularly from the measurement of total activity of 90Sr and 90Y in equilibrium) because of small amount of obtained ash (division of samples into smaller ones makes the analysis even more difficult) reduces their accuracy. Determination of 90Sr from the radiometric measurement of 90Y decay (e.g. after 21 days) eliminates the contribution of possible contamination with U, Th, Ra isotopes and their influence on the final result of analysis. The data presented in Table 4 indicate that 90Sr content in the bones with some exceptions (which may result from consumption of food with various contents of radionuclides) increases with age. Table 4 also includes concentrations of Sr and Ca. As hydroxyapatite is a main component of bones, the Ca concentration is the same in all samples. Of special interest is different concentrations of Sr in the range 50.6e180.9 mg/kg (d.w.) which does not affect explicitly the presence of 90Sr. Taking into account the fact that stable strontium was found in each sample, it can be assumed the isotope exchange between Sr and 90Sr is more reliable than elemental exchange between 90Sr and Ca as often suggested (Lieser, 2008). In the literature (Froidevaux et al., 2006, 2002; Landstetter and Wallner, 2006; Mietelski et al., 2011, 2001; Stamoulis et al., 1999; Tandon et al., 1998) radioactive concentration of 90Sr is given counted over for Ca mass which indicates connection between both cations. Fig. 1 presents 90Sr radioactivity values in human femur (dry weight) as a function of age. The distribution of radioactivity values on two age groups i.e. 56e71 and 77e97 years is visible. In each group maximum of 90Sr concentration may be noticed. It is interesting that such maxima lay in the middle of the age range but not at their borders. More detailed analysis of the connection: patient's
Sr radioactivity in human femur (dry weight).
90
No
Age (years)
90 90 Sr [Bq/kg] Sr [Bq/kg] Sr [Bq/kg] measurement I measurement II average
5 1 9 2 16 4 8 11 15 12 19 10 14 3 6 18 13 17 7
56 62 68 69 71 77 77 77 79 80 82 82 83 84 88 88 90 95 97
0.71 1.27 1.37 0.93 0.47 1.35 0.29 0.63 0.92 1.04 1.11 0.09 0.89 1.38 1.96 0.70 2.82 2.14 1.06
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.04 0.05 0.04 0.07 0.02 0.06 0.02 0.02 0.02 0.04 0.09 0.01 0.03 0.10 0.12 0.06 0.09 0.12 0.04
0.56 0.73 0.51 0.34 0.38 0.11 0.46 0.89 0.60 0.69 0.89 0.45 0.79 0.71 1.09 1.17 0.88 0.73 1.26
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.03 0.03 0.02 0.03 0.02 0.003 0.03 0.04 0.01 0.03 0.07 0.03 0.04 0.002 0.06 0.07 0.04 0.04 0.07
0.64 1.00 0.94 0.64 0.43 0.73 0.37 0.76 0.76 0.87 1.00 0.27 0.84 1.04 1.52 0.94 1.85 1.43 1.16
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.03 0.04 0.03 0.05 0.02 0.03 0.02 0.03 0.02 0.03 0.08 0.02 0.04 0.05 0.09 0.06 0.07 0.08 0.06
Ca [%] Sr [mg/kg] 17.3 17.8 18.1 10.8 18.0 17.1 17.8 16.1 13.4 16.4 17.6 15.0 16.9 14.4 13.4 12.8 12.2 14.1 14.5
105.8 135.0 81.4 104.7 61.3 90.5 103.6 94.6 84.4 150.8 160.6 50.6 170.2 68.9 180.9 137.1 131.3 147.1 172.2
Fig. 1. Concentration of 90Sr radioactivity in human femur (dry weight) in the function of age.
J. Solecki et al. / Journal of Environmental Radioactivity 143 (2015) 85e90
Fig. 2. The cluster analysis of selected data.
age e 90Sr concentration demands careful investigations that may break its secrecy. The data were subjected to cluster analysis using statistiXL v 1.10 program with following parameters: - Distance/Similarity Measure ¼ Pearson Correlation - Cluster Method ¼ Nearest Neighbor. The resulting dendrogram (Fig. 2) univocally demonstrates connection between concentration of strontium in bones and radioactivity of 90Sr. Such behavior justifies conclusion of dominating role of isotope exchange in accumulation of 90Sr in bone tissue. On Fig. 2 the relationship of the concentration of strontium (also 90Sr) with age relation is visible. The presence of radionuclide 90Sr in bones results in a radiation dose. Calculation of doses for an individual from the presence of radioactive in bones requires some assumptions. The density of bones is from 1.8 to 2.0 g/cm3, maximum reach Rmax for 90Sr is 2.1102 mg/cm2 and for 90Y 1.1103 mg/cm2. Based on this it is possible to calculate in which bone layer b radiation will be absorbed. This means that b particles from 90Sr get absorbed in the bone layer 0.1 cm thick and 90Y 0.6 cm thick. Assuming the homogeneous distribution of the emitter, the dose of b absorbed in the soft tissue can be calculated from the equation (Hrynkiewicz, 2001):
Gy kBq ¼ 5:767$104 am $Eb D_ h g
Table 5 Approximate values of radiation doses resulting from the presence of [Bq/kg] radionuclides in human femur.
90
Sr and
Age (years)
90 Sr [kBq/g]
90
Sr Gy/year
90
Sr mSv/year
90
Y Gy/year
90
56 62 68 69 71 77 77 77 79 80 82 82 83 84 88 88 90 95 97
6.4E-07 1.0E-06 9.4E-07 6.4E-07 4.3E-07 7.3E-07 3.7E-07 7.6E-07 7.6E-07 8.7E-07 1.0E-06 2.7E-07 8.4E-07 1.0E-06 1.5E-06 9.4E-07 1.8E-06 1.4E-06 1.2E-06
6.4E-07 1.0E-06 9.5E-07 6.4E-07 4.3E-07 7.4E-07 3.8E-07 7.6E-07 7.7E-07 8.7E-07 1.0E-06 2.7E-07 8.5E-07 1.1E-06 1.5E-06 9.5E-07 1.9E-06 1.4E-06 1.2E-06
7.4E-06 1.2E-05 1.1E-05 7.4E-06 4.9E-06 8.5E-06 4.3E-06 8.8E-06 8.8E-06 1.0E-05 1.2E-05 3.1E-06 9.8E-06 1.2E-05 1.8E-05 1.1E-05 2.1E-05 1.7E-05 1.3E-05
2.9E-06 4.5E-06 4.2E-06 2.9E-06 1.9E-06 3.3E-06 1.7E-06 3.4E-06 3.4E-06 3.9E-06 4.5E-06 1.2E-06 3.8E-06 4.7E-06 6.9E-06 4.2E-06 8.3E-06 6.4E-06 5.2E-06
3.3E-05 5.2E-05 4.9E-05 3.3E-05 2.2E-05 3.8E-05 1.9E-05 3.9E-05 3.9E-05 4.5E-05 5.2E-05 1.4E-05 4.4E-05 5.4E-05 7.9E-05 4.8E-05 9.6E-05 7.4E-05 6.0E-05
90
Y mSv/year
Y
89
where: D_ e the strength of the absorbed dose am e the radioactive concentration of the radionuclide Eb e the average kinetic energy of b electrons Based on the above equation and assuming that this is a soft tissue there were calculated the values of absorbed doses and then the equivalent of the dose for the whole body assuming the tissue (bone) weight factor to be 0.01 for individual people. As follows from the data in Table 5, it can be stated that strontium isotope in the bone tissue does not affect significantly the size of radiation dose. For the territory in Poland the yearly average dose of radiation for the population is about 3.5 mSv/year (“http://www.paa.gov.pl/,” n.d.). Our results can be applied only for the group of people examined and it cannot have the character of epidemiological studies. 4. Conclusions Despite almost complete disappearance of the radioactive fallout in the world, anthropogenic radionuclides accumulated in the environment components get into living organisms with the consumed food and air. The presence of 90Sr and in some cases 137Cs was found in all 19 samples of human femur. Cluster analysis performed on the results univocally showed connection between total concentration of strontium in bone tissue and radioactivity of 90Sr isotope that may suggest dominating role of isotope exchange in accumulation of 90Sr in bones. The correlation between age and radioactivity of 90Sr in bone tissue was noticed but for more detailed conclusions some additional data are necessary. References Froidevaux, P., Geering, J.-J., Valley, J.-F., 2002. Strontium-90 determination in biological and environmental samples by direct milking of its daughter product, yttrium-90. J. Radioanal. Nucl. Chem. 254, 23e27. http://dx.doi.org/10.1023/A: 1020872910506. Froidevaux, P., Geering, J.-J., Valley, J.-F., 2006. 90Sr in deciduous teeth from 1950 to 2002: the Swiss experience. Sci. Total Environ. 367, 596e605. http://dx.doi.org/ 10.1016/j.scitotenv.2006.02.011. zefowicz, E., Liniecki, J., 1999. Awaria czarnobylska Skutki zdroGrabowski, D., Jo wotne w Polsce (No. 4). Polskie Towarzystwo Nukleoniczne. Hrynkiewicz, A., 2001. Człowiek i promieniowanie jonizuja˛ ce. PWN, Warszawa ([WWW Document], n.d). http://www.paa.gov.pl/. IAEA, 2001. Present and Future Environmental Impact of the Chernobyl Accident (No. TECDOC-1240) (Vienna). za _ n ski, P., 2009. Komosa, A., Kitowski, I., Chibowski, S., Solecki, J., Orzeł, J., Ro Selected radionuclides and heavy metals in skeletons of birds of prey from eastern Poland. J. Radioanal. Nucl. Chem. 281, 467e478. http://dx.doi.org/ 10.1007/s10967-009-0029-3. ski, J., 1975. Skazenia _ rcze na wybranych terenach połudKwapulin promieniotwo ˛ sk, Katowice. niowej Polski. Wydawnictwo, Sla Landstetter, C., Wallner, G., 2006. Determination of strontium-90 in deer bones by liquid scintillation spectrometry after separation on Sr-specific ion exchange columns. J. Environ. Radioact. 87, 315e324. http://dx.doi.org/10.1016/ j.jenvrad.2005.12.008. Lieser, K.H., 2008. Nuclear and Radiochemistry: Fundamentals and Applications. John Wiley & Sons. ska, M., Zalewski, M., Tomczak, M., Mietelski, J.W., Gaca, P., Zagrodzki, P., Jasin Vajda, N., Dutkiewicz, E.M., 2001. Sr and stable strontium in bones of wild, herbivorous animals from Poland. J. Radioanal. Nucl. Chem. 247, 363e370. http://dx.doi.org/10.1023/A:1006765920802. Mietelski, J.W., Golec, E.B., Tomankiewicz, E., Golec, J., Nowak, S., Szczygiel, E., Brudecki, K., 2011. Human bones obtained from routine joint replacement surgery as a tool for studies of plutonium, americium and 90Sr body-burden in general public. J. Environ. Radioact. 102, 559e565. http://dx.doi.org/10.1016/ j.jenvrad.2011.02.013. Monetti, M., 1996. Worldwide deposition of Strontium-90 through 1990. Environmental Measurements Laboratory, U.S. Department of Energy. r radiologiczny srodowiska e PTJ, s. Ochrona przed promieniowaniem, 1970. Nadzo Osrodek Informacji o Energii Atomowej, Warszawa. C.L.O.R., 1998. Atlas Radiologiczny Polski, 1997. Biblioteka Monitoringu PIOS, Srodowiska, Warszawa. Roczniki Statystyczne Ochrona Srodowiska, n.d. GUS, Warszawa. ski, M., 1994. Fizyka zagroze _ n srodowiska. Wydawnictwo Naukowe PAN, Siemin Warszawa.
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Determination of radionuclides in samples of middle-aged and older human femurs ski a, *, M. Solecki c J. Solecki a, M. Misztal b, S. Skupin a
Maria Curie Skłodowska University, Faculty of Chemistry, Department of Radiochemistry and Colloid Chemistry, Pl. M. Curie-Skłodowskiej 2, 20-031 Lublin, Poland b Department of Trauma Surgery and Emergency Medicine, Medical University of Lublin, Staszica 16, 20 081 Lublin, Poland c 2nd Department of General Surgery, Medical University of Lublin, Staszica 16, 20 081 Lublin, Poland
a r t i c l e i n f o
a b s t r a c t
Article history: Received 8 September 2014 Received in revised form 3 December 2014 Accepted 4 January 2015 Available online 6 March 2015
The paper presents the studies of the presence of gamma isotopes and 90Sr in 19 middle-to old-aged human femur samples. The samples were taken up during routine orthopedic operations in 2012. The aim of the paper was determination of some radionuclides in human bones and estimation of radiation dose created by 90Sr and 90Y (in bones). The 137Cs, 40K, 226Ra, 228Th, 234Th and 210Pb isotopes were determined by gamma spectrometry. The above mentioned radionuclide contents were in the ranges: 137 Cs (0.04e1.45); 40K (13e86); 226Ra (1e21.5); 228Th (1.4e40.2); 234Th (0.4e5.7); 210Pb (0.7e8.4) Bq/kg d.w. 90Sr was assayed based on radiometric measurement of ingrown 90Y. The 90Sr content was in the range 0.27e1.85 Bq/kg d.w. Measurements of concentration of 90Sr and 90Y in bones were used to estimation of health risk by calculation of radiation dose. Adsorbed doses ranged from 2.7$ 107 to 1.9 $ 106 Gy/y for 90Sr and from 1.2 $ 106 to 8.3 $ 107 Gy/y for 90Y. © 2015 Elsevier Ltd. All rights reserved.
Keywords: Radionuclides Human femur Bones Radiostrontium Radioelements
1. Introduction
CLOR, srodowiska i z_ ywnosci w Polsce w 1999 roku, 2000; PIOS _ 1998; Zarnowiecki, 1988).
The use of a nuclear bomb in 1945 (Hiroshima, Nagasaki) and then intensification of nuclear weapon tests (there were registered 50 nuclear explosions from 10.07.1945 to 31.12.1953) made the public aware of the danger resulting from uncontrolled radioisotope releases. Another sources are from deficiencies in structure and functioning of some reactors and the inconsiderate behavior of their users. These sources resulted in the appearance in the natural environment of, among others, long lived anthropogenic isotopes such as 137Cs 90Sr, 241Am, 238Pu, 239Pu, 240Pu and 241Pu. Considering the half-life (T1/2), it is assumed that the long-lived radionuclides 137 Cs, 90Sr and Pu contribute to the natural environment contamination to the largest extent. Therefore these isotopes should be systematically analysed. Such activities are carried out by some state institutions which publish their results in the form of reports ski, 1975; Nadzo r radiologiczny e.g (Grabowski et al., 1999; Kwapulin srodowiska e PTJ, s. Ochrona przed promieniowaniem, 1970; Roczniki rcze Statystyczne Ochrona Srodowiska, n.d.; Skaz_ enia promieniotwo
Based on the reports by Monetti (1996), and UKAEA (DATE NEEDED) the highest contamination with radiostrontium was found in 1958e1963 which is consistent with the literature data ski, 1994). about the Polish region (Siemin Moreover, as a result of Chernobyl Nuclear Power Station failure there appeared on the European territory the isotopes of the total activity 1.25 1019 Bq including 6.5 1018 Bq of noble gases, 8.14$1015 Bq of 90Sr and from 8.14$1016 to 9.25$1016 Bq of 89Sr; from 1.85$1016 to 4.44$1016 Bq of 134Cs and from 3.70$1016 to 8.51$1016 Bq of 137Cs (IAEA, 2001). Such large amounts of radionuclides introduced into the natural environment require permanent monitoring. 90Sr was recognized as the second after 14C as dangerous from the dosimetric point of view (Lieser, 2008). Harmfulness of 90Sr for living organisms is much higher than that of 137Cs due to emission of two beta particles of total energy higher than gamma quantum, good availability especially in bones (90Sr z Ca replacement of calcium and also long time of incomplete removal e biological half-period). There are a few reports about the presence of radionuclides in bones of animals, birds and people (Froidevaux et al., 2006, 2002; Komosa et al., 2009; Landstetter and Wallner, 2006; Mietelski et al., 2011, 2001; Stamoulis et al., 1999; Tandon et al., 1998;
* Corresponding author. ski). E-mail address: [email protected] (S. Skupin http://dx.doi.org/10.1016/j.jenvrad.2015.01.021 0265-931X/© 2015 Elsevier Ltd. All rights reserved.
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Table 1 Characteristics of studied femur samples. No Gender Age Discase (years)
Sample Sample mass after Ash mass after mass [g] drying [g] d.w. combustion [g]
5 1 9 2 16 4 8 11 15 12 19 10 14 3 6 18 13 17 7
43.0 36.5 39.8 17.7 45.9 33.7 45.2 23.7 25.6 38.2 50.8 19.3 31.1 19.2 19.3 21.5 18.3 23.0 19.8
F F M F M F F F F M M F F F F F F F F
56 62 68 69 71 77 77 77 79 80 82 82 83 84 88 88 90 95 97
os os os fracture os os os fracture fracture fracture os fracture os fracture fracture fracture fracture fracture fracture
39.4 34.1 36.5 16.7 43.1 31.3 41.1 21.5 24.2 35.4 18.2 47.5 29.0 17.4 17.8 20.4 16.5 21.7 18.6
18.2 16.1 18.8 4.9 20.8 14.1 19.1 9.2 8.8 15.3 7.2 22.3 13.2 6.7 6.4 7.3 5.4 8.1 7.1
2. Experimental
F e female, M men, os e osteoporosis and osteoarthrosis.
Table 2 Results of
90
Sr determination in the reference materials.
Name of sample
Reference activity, confidence range [Bq/kg]
IAEAeSOILe6, average from 4 measurements IAEAe375, average from 3 measurements flour I (PAA) flour II (PAA) Word-wide open proficiency test IAEA e CO-2007-03 Spinach IAEA-30
30.34 (24.20e31.67)
MDA value Activity determined and calculated on the [Bq/kg] reference date [Bq/kg] 34.8 ± 4.3
0.02
108 (101e114)
104.2 ± 23.9
0.02
0.15 ± 0.05 0.48 ± 0.01 20.1 ± 2.1
0.18 ± 0.03 0.47 ± 0.03 20.89 ± 1.38
0.01 0.01 0.02
(1998). It discussed the problems connected with the presence of some trace elements in bones and analytical difficulties caused by material specification, its complex character and variety as well as verification of results. Taking into account the above quoted literature reports, the attempt was made to apply the information about uptake and preparation of samples as well as determination methods.
Bone samples (femoral heads) were acquired during routine total hip arthroplasty. The project has been approved by Bioethical Council of Medical University of Lublin. Samples were taken from anonymous patients during surgical operations. After surgeries the bones were cleaned of any soft tissues, washed with saline and each frozen in a separate containers. Then all samples were collected, bones were defrosted and underwent physical examination (weight, volume etc). Each head was then divided into smaller pieces with a chisel and separately suspended the excessive amount of Benzinum Purum to flush the fat. Sample symbols and their characterization are shown in Table 1. Then the samples were taken from Benzinum Purum, placed on a Perti pan and dried at 60 C for 24 h. Next they were weighed, disintegrated using a hydraulic press, again put on the pans and dried to constant mass at 105 C for 24 h. The dried bones were moved quantitatively into porcelain beakers and after covering them with quartz glasses placed in the high temperature oven with automatic temperature regulation. The combustion process proceeded as follows: after reaching the temperature 200 C for 10 hours, the oven was heated for another 10 hours, the temperature was increased up to 400 C for 3 hours, and heated for 6 hours, the temperature was increased to 600 C for 3 hours and heated for 10 hours.
Wallova et al., 2012). Such research is particularly difficult because of necessity of obtaining samples, especially difficult for human bones, and the structure and composition of bone itself. One of the significant papers on bone analysis is the review by Tandon et al.
After cooling the ash was examined with respect to colour. In all cases it was gray powder which indicates proper mineralization without carbon formation. The samples were weighed to determine the ash mass (Table 1). The whole amount of ash was moved quantitatively to flat polyethylene boxes of thin walls. An aliquot of 0.2 g was taken and after the addition of 7.8 g of a flux, it was melted in a platinum
Table 3 Radioactive concentration of determined gamma radionuclides in human femur. No
Age (years)
137
5 1 9 2 16 4 8 11 15 12 19 10 14 3 6 18 13 17 7
56 62 68 69 71 77 77 77 79 80 82 82 83 84 88 88 90 95 97
0.58 ± 0.39 0.14 ± 0.09 0.60 ± 0.49
Cs [Bq/kg d.w.]
40
226
2.5 ± 2.8 3.9 ± 3.5
K [Bq/kg d.w.]
Ra [Bq/kg d.w.]
228
Th [Bq/kg d.w.]
234
Th [Bq/kg d.w.]
3.9 ± 4.9 4.9 ± 13.1 5.4 ± 9.9 2.6 ± 3.6
210
Pb [Bq/kg d.w.]
0.7 ± 4.4 2.7 ± 5.3 4.1 ± 4.7 1.5 ± 1.7 2.8 ± 3.4 1.0 ± 6.3 5.2 ± 4.6
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crucible to obtain the samples for determination of metal cations including Ca and Sr by means of the WD-XRF method. The other part was weighed and measured in preparation for gamma spectrometry. The spectrometer produced by Silena had a germanium detector IGCe13 (Princeton GammaeTech) cooled with liquid nitrogen with 4096 channel amplitude analyzer. The detector capacity on the 60Co (1.33 MeV) was 15%. The gamma spectra were
subjected to measurements were placed in plastic boxes of the size to the type of the source used during calibration. After the gamma spectrometry, the samples were quantitatively moved to 250 cm3 beakers and weighed again. The whole amount of ash was used for 90Sr determination. The methods were based on evolution of 90Y, the product of strontium decay. The analysis was made according to the scheme:
analyzed by means of the computer program GENIE 2000. As the calibration model a standard source was used as prepared by the Central Laboratory of Radiological Protection (Poland) with the symbol SZN http://www.clor.waw.pl. The source was of disk shape, 3 mm high and 49 mm diameter made on the basis of polymer of about 1 g/cm3 density. The samples
Methods of 90Sr determination based on ingrowth and radiometric measurements of 90Y radioactive (secular) equilibrium allow to trace radiochemical purity (measurement of background after 90 Y decay) on one hand and to repeat the analysis of the same sample after equilibrium re-establishment (minimum 14 days) in the primary sample, on the other hand.
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For radiometric measurements there was applied a low-boiler counter LSC Quantulus 1220 e Wallac Perkin Elmer with computer programs for communication with the instrument and collection of the data WinQ as well as interpretation of radioactive spectra Easy View. The yield of counting was 100% in carbon channels. The measurement was performed for 300 min. The counting rate was registered in cpm. The data registered on the spectra of 90Y in the channels from 350 to 850 were taken in calculations. The determination method was tested using the reference materials and in the interlaboratory measurements. The results are presented in Table 2. The results of 90Sr determination (particularly for spinach samples) presented in Table 2 show that the proposed method obtained correct data. However, it should be noticed that bones belong to the samples of differentiated matrices as pointed out by Tandon et al. (1998), therefore preparation of reference material for such samples is very difficult. The reference samples proposed by MAEA, as a rule, contain many times higher concentrations of radionulcides than their contents determined in the samples. The samples of e.g. soil, flour, water prepared by the Institute of Chemistry and Nuclear Technique in Warsaw commissioned by the State Atomistic Agency (PAA) within the interlaboratory tests include the concentrations of radionuclides close to the level of their contents in environmental samples e.g. flour in Table 2. Determination of a given radionuclide in this type of samples makes the proposed method more reliable.
3. Results and discussion As can be seen in Table 3 the contents of radionuclides were in the ranges: 137Cs (0.04e1.45); 40K (13e86); 226Ra (1e21.5); 228Th (1.4e40.2); 234Th (0.4e5.7); 210Pb (0.7e8.4) Bq/kg d.w. Generally, it can be accepted that concentration of these radioelements increases with the person's age. The presence in bones of 137Cs is the evidence for its occurrence in food products (Solecki and Kruk, 2011) e.g. 0.3e0.9 Bq/dm3 in milk and in atmospheric air <0.1e5.4 mBq/m3 was found (“http://www.paa.gov.pl/,” n.d.). Cesium radionuclide half-period of effective biological removal is 60 days (Lieser, 2008), so with the practical disappearance of the world fall-out, its occurrence in bones can be due to the failure of Nuclear Power Station in Chernobyl.
Table 4 Concentration of
90
Table 4 presents the results of 90Sr determination in the bone samples. The methods allowed to make a few measurements from one sample. Column III in the Table 4 presents the results of 90Sr determination for the primary sample that is after dissolution of ash in HNO3, separation of 90Y and measurement of its activity. According to the procedure presented in the experimental part, after separation of 90Y, the solution still containing 90Sr was left for 14 days in order to establish equilibrium between 90Sre90Y. Then there was made repeated determination of 90Sr by removing 90Y from the primary sample. The results of the second determination are given in column IV in Table 4. This analytical procedure allows calculation of average values which improve determination reliability as follows from the data in Table 4, presentation of the results from one measurement, which in the case of bone sample (particularly from the measurement of total activity of 90Sr and 90Y in equilibrium) because of small amount of obtained ash (division of samples into smaller ones makes the analysis even more difficult) reduces their accuracy. Determination of 90Sr from the radiometric measurement of 90Y decay (e.g. after 21 days) eliminates the contribution of possible contamination with U, Th, Ra isotopes and their influence on the final result of analysis. The data presented in Table 4 indicate that 90Sr content in the bones with some exceptions (which may result from consumption of food with various contents of radionuclides) increases with age. Table 4 also includes concentrations of Sr and Ca. As hydroxyapatite is a main component of bones, the Ca concentration is the same in all samples. Of special interest is different concentrations of Sr in the range 50.6e180.9 mg/kg (d.w.) which does not affect explicitly the presence of 90Sr. Taking into account the fact that stable strontium was found in each sample, it can be assumed the isotope exchange between Sr and 90Sr is more reliable than elemental exchange between 90Sr and Ca as often suggested (Lieser, 2008). In the literature (Froidevaux et al., 2006, 2002; Landstetter and Wallner, 2006; Mietelski et al., 2011, 2001; Stamoulis et al., 1999; Tandon et al., 1998) radioactive concentration of 90Sr is given counted over for Ca mass which indicates connection between both cations. Fig. 1 presents 90Sr radioactivity values in human femur (dry weight) as a function of age. The distribution of radioactivity values on two age groups i.e. 56e71 and 77e97 years is visible. In each group maximum of 90Sr concentration may be noticed. It is interesting that such maxima lay in the middle of the age range but not at their borders. More detailed analysis of the connection: patient's
Sr radioactivity in human femur (dry weight).
90
No
Age (years)
90 90 Sr [Bq/kg] Sr [Bq/kg] Sr [Bq/kg] measurement I measurement II average
5 1 9 2 16 4 8 11 15 12 19 10 14 3 6 18 13 17 7
56 62 68 69 71 77 77 77 79 80 82 82 83 84 88 88 90 95 97
0.71 1.27 1.37 0.93 0.47 1.35 0.29 0.63 0.92 1.04 1.11 0.09 0.89 1.38 1.96 0.70 2.82 2.14 1.06
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.04 0.05 0.04 0.07 0.02 0.06 0.02 0.02 0.02 0.04 0.09 0.01 0.03 0.10 0.12 0.06 0.09 0.12 0.04
0.56 0.73 0.51 0.34 0.38 0.11 0.46 0.89 0.60 0.69 0.89 0.45 0.79 0.71 1.09 1.17 0.88 0.73 1.26
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.03 0.03 0.02 0.03 0.02 0.003 0.03 0.04 0.01 0.03 0.07 0.03 0.04 0.002 0.06 0.07 0.04 0.04 0.07
0.64 1.00 0.94 0.64 0.43 0.73 0.37 0.76 0.76 0.87 1.00 0.27 0.84 1.04 1.52 0.94 1.85 1.43 1.16
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.03 0.04 0.03 0.05 0.02 0.03 0.02 0.03 0.02 0.03 0.08 0.02 0.04 0.05 0.09 0.06 0.07 0.08 0.06
Ca [%] Sr [mg/kg] 17.3 17.8 18.1 10.8 18.0 17.1 17.8 16.1 13.4 16.4 17.6 15.0 16.9 14.4 13.4 12.8 12.2 14.1 14.5
105.8 135.0 81.4 104.7 61.3 90.5 103.6 94.6 84.4 150.8 160.6 50.6 170.2 68.9 180.9 137.1 131.3 147.1 172.2
Fig. 1. Concentration of 90Sr radioactivity in human femur (dry weight) in the function of age.
J. Solecki et al. / Journal of Environmental Radioactivity 143 (2015) 85e90
Fig. 2. The cluster analysis of selected data.
age e 90Sr concentration demands careful investigations that may break its secrecy. The data were subjected to cluster analysis using statistiXL v 1.10 program with following parameters: - Distance/Similarity Measure ¼ Pearson Correlation - Cluster Method ¼ Nearest Neighbor. The resulting dendrogram (Fig. 2) univocally demonstrates connection between concentration of strontium in bones and radioactivity of 90Sr. Such behavior justifies conclusion of dominating role of isotope exchange in accumulation of 90Sr in bone tissue. On Fig. 2 the relationship of the concentration of strontium (also 90Sr) with age relation is visible. The presence of radionuclide 90Sr in bones results in a radiation dose. Calculation of doses for an individual from the presence of radioactive in bones requires some assumptions. The density of bones is from 1.8 to 2.0 g/cm3, maximum reach Rmax for 90Sr is 2.1102 mg/cm2 and for 90Y 1.1103 mg/cm2. Based on this it is possible to calculate in which bone layer b radiation will be absorbed. This means that b particles from 90Sr get absorbed in the bone layer 0.1 cm thick and 90Y 0.6 cm thick. Assuming the homogeneous distribution of the emitter, the dose of b absorbed in the soft tissue can be calculated from the equation (Hrynkiewicz, 2001):
Gy kBq ¼ 5:767$104 am $Eb D_ h g
Table 5 Approximate values of radiation doses resulting from the presence of [Bq/kg] radionuclides in human femur.
90
Sr and
Age (years)
90 Sr [kBq/g]
90
Sr Gy/year
90
Sr mSv/year
90
Y Gy/year
90
56 62 68 69 71 77 77 77 79 80 82 82 83 84 88 88 90 95 97
6.4E-07 1.0E-06 9.4E-07 6.4E-07 4.3E-07 7.3E-07 3.7E-07 7.6E-07 7.6E-07 8.7E-07 1.0E-06 2.7E-07 8.4E-07 1.0E-06 1.5E-06 9.4E-07 1.8E-06 1.4E-06 1.2E-06
6.4E-07 1.0E-06 9.5E-07 6.4E-07 4.3E-07 7.4E-07 3.8E-07 7.6E-07 7.7E-07 8.7E-07 1.0E-06 2.7E-07 8.5E-07 1.1E-06 1.5E-06 9.5E-07 1.9E-06 1.4E-06 1.2E-06
7.4E-06 1.2E-05 1.1E-05 7.4E-06 4.9E-06 8.5E-06 4.3E-06 8.8E-06 8.8E-06 1.0E-05 1.2E-05 3.1E-06 9.8E-06 1.2E-05 1.8E-05 1.1E-05 2.1E-05 1.7E-05 1.3E-05
2.9E-06 4.5E-06 4.2E-06 2.9E-06 1.9E-06 3.3E-06 1.7E-06 3.4E-06 3.4E-06 3.9E-06 4.5E-06 1.2E-06 3.8E-06 4.7E-06 6.9E-06 4.2E-06 8.3E-06 6.4E-06 5.2E-06
3.3E-05 5.2E-05 4.9E-05 3.3E-05 2.2E-05 3.8E-05 1.9E-05 3.9E-05 3.9E-05 4.5E-05 5.2E-05 1.4E-05 4.4E-05 5.4E-05 7.9E-05 4.8E-05 9.6E-05 7.4E-05 6.0E-05
90
Y mSv/year
Y
89
where: D_ e the strength of the absorbed dose am e the radioactive concentration of the radionuclide Eb e the average kinetic energy of b electrons Based on the above equation and assuming that this is a soft tissue there were calculated the values of absorbed doses and then the equivalent of the dose for the whole body assuming the tissue (bone) weight factor to be 0.01 for individual people. As follows from the data in Table 5, it can be stated that strontium isotope in the bone tissue does not affect significantly the size of radiation dose. For the territory in Poland the yearly average dose of radiation for the population is about 3.5 mSv/year (“http://www.paa.gov.pl/,” n.d.). Our results can be applied only for the group of people examined and it cannot have the character of epidemiological studies. 4. Conclusions Despite almost complete disappearance of the radioactive fallout in the world, anthropogenic radionuclides accumulated in the environment components get into living organisms with the consumed food and air. The presence of 90Sr and in some cases 137Cs was found in all 19 samples of human femur. Cluster analysis performed on the results univocally showed connection between total concentration of strontium in bone tissue and radioactivity of 90Sr isotope that may suggest dominating role of isotope exchange in accumulation of 90Sr in bones. The correlation between age and radioactivity of 90Sr in bone tissue was noticed but for more detailed conclusions some additional data are necessary. References Froidevaux, P., Geering, J.-J., Valley, J.-F., 2002. Strontium-90 determination in biological and environmental samples by direct milking of its daughter product, yttrium-90. J. Radioanal. Nucl. Chem. 254, 23e27. http://dx.doi.org/10.1023/A: 1020872910506. Froidevaux, P., Geering, J.-J., Valley, J.-F., 2006. 90Sr in deciduous teeth from 1950 to 2002: the Swiss experience. Sci. Total Environ. 367, 596e605. http://dx.doi.org/ 10.1016/j.scitotenv.2006.02.011. zefowicz, E., Liniecki, J., 1999. Awaria czarnobylska Skutki zdroGrabowski, D., Jo wotne w Polsce (No. 4). Polskie Towarzystwo Nukleoniczne. Hrynkiewicz, A., 2001. Człowiek i promieniowanie jonizuja˛ ce. PWN, Warszawa ([WWW Document], n.d). http://www.paa.gov.pl/. IAEA, 2001. Present and Future Environmental Impact of the Chernobyl Accident (No. TECDOC-1240) (Vienna). za _ n ski, P., 2009. Komosa, A., Kitowski, I., Chibowski, S., Solecki, J., Orzeł, J., Ro Selected radionuclides and heavy metals in skeletons of birds of prey from eastern Poland. J. Radioanal. Nucl. Chem. 281, 467e478. http://dx.doi.org/ 10.1007/s10967-009-0029-3. ski, J., 1975. Skazenia _ rcze na wybranych terenach połudKwapulin promieniotwo ˛ sk, Katowice. niowej Polski. Wydawnictwo, Sla Landstetter, C., Wallner, G., 2006. Determination of strontium-90 in deer bones by liquid scintillation spectrometry after separation on Sr-specific ion exchange columns. J. Environ. Radioact. 87, 315e324. http://dx.doi.org/10.1016/ j.jenvrad.2005.12.008. Lieser, K.H., 2008. Nuclear and Radiochemistry: Fundamentals and Applications. John Wiley & Sons. ska, M., Zalewski, M., Tomczak, M., Mietelski, J.W., Gaca, P., Zagrodzki, P., Jasin Vajda, N., Dutkiewicz, E.M., 2001. Sr and stable strontium in bones of wild, herbivorous animals from Poland. J. Radioanal. Nucl. Chem. 247, 363e370. http://dx.doi.org/10.1023/A:1006765920802. Mietelski, J.W., Golec, E.B., Tomankiewicz, E., Golec, J., Nowak, S., Szczygiel, E., Brudecki, K., 2011. Human bones obtained from routine joint replacement surgery as a tool for studies of plutonium, americium and 90Sr body-burden in general public. J. Environ. Radioact. 102, 559e565. http://dx.doi.org/10.1016/ j.jenvrad.2011.02.013. Monetti, M., 1996. Worldwide deposition of Strontium-90 through 1990. Environmental Measurements Laboratory, U.S. Department of Energy. r radiologiczny srodowiska e PTJ, s. Ochrona przed promieniowaniem, 1970. Nadzo Osrodek Informacji o Energii Atomowej, Warszawa. C.L.O.R., 1998. Atlas Radiologiczny Polski, 1997. Biblioteka Monitoringu PIOS, Srodowiska, Warszawa. Roczniki Statystyczne Ochrona Srodowiska, n.d. GUS, Warszawa. ski, M., 1994. Fizyka zagroze _ n srodowiska. Wydawnictwo Naukowe PAN, Siemin Warszawa.
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Tandon, L., Iyengar, G.V., Parr, R.M., 1998. A review of radiologically important trace elements in human bones. Appl. Radiat. Isot. 49, 903e910. http://dx.doi.org/ 10.1016/S0969-8043(97)10102-6. Wallova, G., Kandler, N., Wallner, G., 2012. Monitoring of radionuclides in soil and bone samples from Austria. J. Environ. Radioact. 107, 44e50. http://dx.doi.org/ 10.1016/j.jenvrad.2011.12.007. _ _ n promieniotwo rczych i zagrozenia _ Zarnowiecki, K., 1988. Analiza skaze radiologicznego w Polsce po awarii elektrowni ja˛ drowej w Czarnobylu. CLOR.