|Year : 2011 | Volume
| Issue : 1 | Page : 26-28
Biokinetic studies of strontium for Indian adult population using the data on its daily intake and serum content
Suma Nair, Sharda Bhati
Internal Dosimetry Section, Health Physics Division, Bhabha Atomic Research Centre, Bombay, India
|Date of Web Publication||17-Mar-2012|
Internal Dosimetry Section, Health Physics Division, Bhabha Atomic Research Centre, Bombay
Source of Support: None, Conflict of Interest: None
The daily dietary intake of strontium and it's content in blood serum for Indian adult population were estimated experimentally by measuring the concentration of stable Sr in total cooked diet and blood serum samples using radiochemical neutron activation analysis technique (RNAA). This paper reports some preliminary results obtained in the estimation of gut absorption factor (f 1 ) values of Sr in Indian adult population using data on it's daily dietary intake and blood serum content. The estimated f 1 values of Sr in Indian adult population were compared with the reported ICRP values.
Keywords: Serum content, radiochemical neutron activation analysis, gut absorption factor
|How to cite this article:|
Nair S, Bhati S. Biokinetic studies of strontium for Indian adult population using the data on its daily intake and serum content. Radiat Prot Environ 2011;34:26-8
|How to cite this URL:|
Nair S, Bhati S. Biokinetic studies of strontium for Indian adult population using the data on its daily intake and serum content. Radiat Prot Environ [serial online] 2011 [cited 2020 Jan 28];34:26-8. Available from: http://www.rpe.org.in/text.asp?2011/34/1/26/93900
| 1. Introduction|| |
90 Sr is an important fission product produced in the nuclear reactor operation. The testing of nuclear weapons is another important source of production of this radionuclide. The exposure of occupational workers and also the general public to this radionuclide could lead to it's deposition in the human body and subsequently to internal radiation dose. The realistic assessment of internal dose for radiation workers exposed to this radionuclide, primarily depends upon it's retention pattern, which is an important biokinetic parameter. In this study, the data on daily dietary intake of stable strontium and it's content in blood serum for adult Indian population were estimated and which then can be used for the biokinetic studies of its radioactive counterparts. The concentration of stable strontium in total cooked diet and blood serum samples were experimentally determined using radiochemical neutron activation analysis technique (RNAA). In this paper, the data on daily dietary strontium 0 intake and it's content in blood serum were used for estimating the gut absorption factor f 1 which is an important biokinetic parameter. The estimated value of f 1 was compared with the reported values given by ICRP.
| 2. Materials and Methods|| |
2.1 Sampling and sample preparation
The commonly employed method for studying the daily dietary intake of trace elements are based on the analysis of duplicate diet, market basket, or the cooked total diet. In the present study, cooked total diet samples were used to determine the concentration of stable strontium. In order to constitute a representative diet sample for average Indian adult, cereals and pulses were purchased from different regions of the country and were mixed in equal proportions. The other food materials like vegetables, fruits, etc. were purchased from local markets and specified weights of various food materials were taken and meals representing adult diets of different states as well as of national average were prepared (Dang et al., 2001). About 2.2 litre of drinking water evaporated to about one fourth volume was added to the cooked food and the total material was homogenized using a mixer blender. The homogenized samples were then freeze dried, and powdered and three aliquots weighing about 500 mg were taken in pre-cleaned polythene bags for analysis. Blood samples (15 ml) from healthy adults who came for blood donation between the ages 20-45 years were collected and the serum was separated. The separated serum was dried and taken in sealed pre-cleaned polythene bag for analysis.
2.2 Analytical procedure
There are few suitable analytical methods available to determine the concentrations of trace elements in nanogram levels found in most of the biological samples. The analytical method employing neutron activation analysis technique (NAA) was found to be one of the most effective in determining the concentration of Sr in food materials as well as in human tissues. The advantage of NAA over other analytical methods lies in the fact that it is blank free and matrix independent technique. It is also adequately sensitive for the measurement of elemental concentration in nanogram levels. The RNAA technique (Suma Nair et al. 2005 and 2006) was used for the determination of the Sr concentration in total diet and blood serum samples. All the samples were irradiated with 100 ng of Sr standard for 30 minutes at neutron flux of 10 12 n/cm 2 /sec in APSARA reactor at BARC. On neutron irradiation, 87m Sr was produced from the stable 86 Sr present in the irradiated sample by the nuclear reaction 86 Sr (n,γ) 87m Sr. The activation product 87m Sr were chemically separated from other interfering radionuclides.
The irradiated samples were digested in concentrated nitric acid in the presence of about 100 microgram of (stable isotope) strontium carrier and 50mg of calcium carrier, till a clear solution was obtained. To the clear solution, about 10 ml of oxalic acid was added and calcium oxalate was precipitated by adding liquid ammonia. The calcium oxalate precipitate quantitatively carried 87m Sr along with it. The calcium oxalate precipitate was filtered and counted for the characteristic gamma line of 389 keV. The Sr standard which was irradiated along with the sample was also subjected to the same radio chemical separation counted in the same geometry using 54 CC hyper pure Germanium detector coupled to multi channel analyser. The nuclear parameters employed in the measurement of Sr are given in [Table 1].
|Table 1: Nuclear parameters involved in the determination of Sr by neutron activation analysis technique|
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| 3. Results and Discussions|| |
[Table 2] shows the results of analysis of Standard Reference Materials (SRMs) such as total diet, bovine muscle, citrus leaves, orchard leaves, pine needle and oyster tissue obtained from NIST-USA. It can be seen that the values obtained in the present work are comparable (within 10%) with the certified/literature values, indicating the reliability of the analysis.
|Table 2: Concentration of Sr (ìg/gm) in selected standard reference materials|
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The mean concentration of Sr in the cooked diet was multiplied with the total weight of the cooked diet to estimate the daily dietary intake of Sr in an average Indian adult. From [Table 3] it is seen that the daily dietary intake of Sr for an average Indian adult ranges from 0.79 to 2.96 mg with an arithmetic mean and geometric mean values of 1.59 mg and 1.46 mg, respectively. Similarly the mean concentration of Sr in the serum samples of adults was multiplied with the average serum volume of 2.5 L in Indian adult man to obtain the serum content. The estimated serum content for adult Indians varies from 11.3μg to 122.5μg with an arithmetic mean and geometric mean of 40.1μg and 50.1 g respectively as shown in [Table 3].
|Table 3: Daily intake and serum content of Sr in average adult Indian population|
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The data on daily strontium intake and it's content in blood serum for Indian adults were employed to arrive at the gut absorption factor f 1 , which was found to vary from 0.01 to 0.1. The observed f 1 values in Indian adults were compared with the reported ICRP values. The ICRP (ICRP Publication 67, 1993) recommends a value of 0.3 as f 1 for all soluble compounds of Sr and 0.01 for the poorly absorbed compounds in adult members of the public. The preliminary results of this study have shown that the observed gut absorption values for soluble Sr compounds in Indian population is less than that of ICRP reported values.
| 4. Conclusions|| |
The daily dietary intake of strontium and its content in blood serum for Indian adult population were estimated experimentally using radiochemical neutron activation analysis technique and used the data for estimating the gut absorption factor f 1. The daily dietary intake of Sr for an average Indian adult ranges from 0.79 to 2.96 mg with an arithmetic mean and a geometric mean of 1.59 mg and 1.46 mg respectively. The estimated serum content for adult Indians varies from 11.3μg to 122.5μg with an arithmetic mean and geometric mean of 40.1μg and 50.1 g, respectively. The observed gut absorption values for Indian population were found to vary from 0.01 to 0.1 which are less than that of ICRP reported values. This study can be used for the assessment of internal doses to the exposed occupational workers and to the general public due to the ingestion of radioactive strontium.
| 5. References|| |
- Dang H. S., Jaiswal D. D., Pullat V.R., Parameswaran M. and Suma Nair (2001), The estimation of Daily Intake and Organ content of some Selected Trace Elements of importance in Radiation Protection and Nutrition in Indian population for Application of the data to study their biokinetics, Final report to IAEA on Research Contact No.RC-8919/Japan.
- ICRP (1993), Age dependent doses to the member of public from intake of radionuclides, Part 2 ICRP publication 67, 1993.
- Suma Nair, Pradhan A. S., Jaiswal D. D., Singh I. S. and Gurg S. P. (2006), Comparison of Observed Skeleton Retention of Strontium in Average Indian Adult with the Value Predicted by ICRP Biokinetic Model, Radiation Protection Dosimetry, 118, 475-478.
- Suma Nair, Pradhan A. S., Jaiswal D. D., Singh I. S. and Gurg S. P. (2005), Comparison of measured Strontium, Cesium and Iodine in Skeleton, Skeletal muscle and thyroid in an average Indian adult with the value predicted by the ICRP biokinetic model, Radiation Protection and Environment, 28, 356-358.
[Table 1], [Table 2], [Table 3]