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Isotopic and Nuclear Analytical Techniques for Health and Environment

Isotopic and Nuclear Analytical Techniques for Health and Environment 10 - 13 June 2003 , Vienna, Austria. 90 Sr IN VARIOUS FOOD AND FOODSTUFFS U. R epin c , L. Benedik , R. Jakopic Department of Environmental Sciences Jo z ef Stefan Institute , Jamova 39, 1000 Ljubljana, SLOVENIA.

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Isotopic and Nuclear Analytical Techniques for Health and Environment

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  1. Isotopic and Nuclear Analytical Techniques for Health and Environment 10 - 13 June 2003, Vienna, Austria 90Sr IN VARIOUS FOOD AND FOODSTUFFSU.Repinc, L. Benedik,R. Jakopic Department of Environmental SciencesJozef Stefan Institute, Jamova 39, 1000 Ljubljana, SLOVENIA

  2. Major pathways of radionuclides to man

  3. Radionuclides of interest - produced in fission processes which may contribute significantly to human exposure

  4. Characteristics of strontium 89Sr (t1/2 = 50.5 d, Emax = 1.49 MeV)  89Y (stable) 90Sr (t1/2 = 28.7 y, Emax = 0.546 MeV)  90Y (t1/2 = 64.1h, Emax = 2.28 MeV)  90 Zr (stable) IIA. Group of the Periodic Table • chemically similar to calcium • 20-30% of absorbed Sr is deposited in the bone, 1% is distributed among the blood volume, extracellular fluid, soft tissue, and surface of the bone • internal exposure to Sr-90 is linked to bone cancer, cancer of the soft tissue near the bone and leukemia

  5. 90Sr • is considered one of the most hazardous fission products: • high fission yield • has a long physical half-life (28.7 years) • has a long biological half-life (49.3 years) • high radiotoxicity due to its tendency to deposit in bones • is one of the main component of fallout activity after an accident: • - high fission yield • - relatively short-lived (50.5 days), decays to undetectable levels in a few months • - it is not considered as hazardous as 90Sr 89Sr

  6. Food sampling • individual food items, not total diet samples (to indicate which countermeasures should be taken to reduce population exposure) • radionuclides most likely to be present in terrestrial food and environment or can be rapidly accumulated by fresh water or marine organisms like oysters, clams, shrimp, etc.

  7. Samples selected • foodstuffs for infants • milk powder, fruit milk mash, • infant milk, wheat flakes • - eggs: whitesand yolk • sea food • golden grey mullet, gilthead seabream, European anchovy, mussels • - meat(beef) • - freshwater fish: trout • vegetables: cabbage, potato

  8. Strontium separation procedure preconcentration of alkaline elements K and Si removal separation of strontium and calcium Ca removal removal of Fe, Al

  9. Strontium separation procedure – cont. removal of Ba, Ra, Pb centrifugation on 22 mm diameter planchette, drying  determination of the chemical yield by weighing SrCO3  measurement of 89Sr, 90Sr/90Y on beta counter

  10. Beta counting • 22 mm diameter planchettes • calibrated with 90Sr/90Y standard • 17% counting efficiency, 90Sr 43% counting efficiency, 90Y A multilogger LB 5310 low-level gas proportional counter (Berthold Inc., Bad Wildbad, Germany)

  11. 90Sr activity calculation A - 90Sr activity in the sample, Bq/kg R - count rate of the sample (without background), cpm Rs+b -count rate of the sample and background, cpm Rb – background count rate, cpm ts – measuring time, sample tb – measuring time, background YSr – chemical yield of the separation Sr-90 - counting efficiency for 90Sr Y-90 – counting efficiency for 90Y m - sample weight (kg) h – decay constant for 90Y (1.8022E-4 min-1) t – ingrowth time from separation of 90Sr to counting (min)

  12. Results TABLE I. RESULTS OF 90Sr DETERMINATION IN SELECTED FOOD AND FOODSTUFF SAMPLES, Bq/kg FRESH WEIGHT

  13. TABLE II.RESULTS FOR 90Sr IN FRESHWATER FISH SAMPLES, INCLUDED IN THE KRŠKO NPPMONITORING PROGRAMME

  14. TABLE III. RESULTS OF Sr-90 DETERMINATION IN SELECTED FOOD AND FOODSTUFF SAMPLES, Bq/kg FRESH WEIGHT TABLE IV. COUNCIL REGULATION (EURATOM) NO.3954/87 OF 22 DECEMBER 1987

  15. Conclusions • activity concentrations in selected food and foodstuff samples are low (below detectable 0.01 to 0.9 Bq/kg 90Sr) • activity concentrations in selected food and foodstuff samples are below maximum permitted levels of radioactive contamination laid down in EU regulations • no significant differences in freshwater fish samples from the vicinity of NPP Krško could be observed due to the operation of NPP • results confirm that selected food and foodstuffs do not represent a health hazard to the population

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