90Sr IN VARIOUS FOOD AND FOODSTUFFS U' Repinc, L' Benedik, R' Jakopic Department of Environmental Sc

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90Sr IN VARIOUS FOOD AND FOODSTUFFS U. Repinc,
L. Benedik, R. Jakopic Department of
Environmental Sciences Jozef Stefan Institute,
Jamova 39, 1000 Ljubljana, SLOVENIA
Isotopic and Nuclear Analytical Techniques for
Health and Environment 10 - 13 June 2003,
Vienna, Austria
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Major pathways of radionuclides to man
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Radionuclides of interest
- produced in fission processes which may
contribute significantly to human exposure
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Characteristics of strontium
90Sr (t1/2 28.7 y, Emax 0.546 MeV) ? 90Y
(t1/2 64.1h, Emax 2.28 MeV) ? 90 Zr (stable)

• 89Sr (t1/2 50.5 d, Emax 1.49 MeV) ??
• 89Y (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

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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
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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.

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Samples selected

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

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Strontium separation procedure
preconcentration of alkaline elements
K and Si removal
separation of strontium and calcium

Ca removal
removal of Fe, Al
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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
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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)
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90Sr activity calculation
A - 90Sr activity in the sample, Bq/kg R - count
rate of the sample (without background), cpm Rsb
-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)
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Results
TABLE I. RESULTS OF 90Sr DETERMINATION IN
SELECTED FOOD AND FOODSTUFF SAMPLES, Bq/kg FRESH
WEIGHT
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TABLE II. RESULTS FOR 90Sr IN FRESHWATER FISH
SAMPLES, INCLUDED IN THE KRKO NPP MONITORING
PROGRAMME
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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
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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 Krko 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