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Irradiation of members of the general public from radioactive caesium following the Chernobyl reactor accident. Field studies in a highly contaminated area in the Bryansk region, Russia.

Thornberg, Charlotte LU (2000)
Abstract (Swedish)
Popular Abstract in Swedish

Bestrålning av allmänheten från radioaktivt cesium efter Tjernobylolyckan. Fältstudier i ett högkontaminerat område i Bryanskregionen i Ryssland.



Olyckan i kärnkraftverket i Tjernobyl i Ukraina 1986 orsakade att stora delar av Europa kontaminerades med radioaktiva ämnen, varav 137Cs är det som fortfarande finns kvar pga sin långa halveringstid (30.2 år). Bryanskområdet i sydvästra Ryssland, ca 20 mil från Tjernobyl, fick ganska höga depositionsnivåer av 137Cs, pga att det regnade då ett moln från reaktorn passerade området. 1990 initierades ett samarbete mellan Radiofysikavdelningarna i Malmö och Göteborg och Strålskyddsinstituten i Sverige, Ryssland och Norge. Efter 1993... (More)
Popular Abstract in Swedish

Bestrålning av allmänheten från radioaktivt cesium efter Tjernobylolyckan. Fältstudier i ett högkontaminerat område i Bryanskregionen i Ryssland.



Olyckan i kärnkraftverket i Tjernobyl i Ukraina 1986 orsakade att stora delar av Europa kontaminerades med radioaktiva ämnen, varav 137Cs är det som fortfarande finns kvar pga sin långa halveringstid (30.2 år). Bryanskområdet i sydvästra Ryssland, ca 20 mil från Tjernobyl, fick ganska höga depositionsnivåer av 137Cs, pga att det regnade då ett moln från reaktorn passerade området. 1990 initierades ett samarbete mellan Radiofysikavdelningarna i Malmö och Göteborg och Strålskyddsinstituten i Sverige, Ryssland och Norge. Efter 1993 deltog endast de svenska och ryska grupperna. I september eller oktober månad varje höst mellan 1990 och 1998 gjordes expeditioner till området för att mäta stråldoserna till människor i de drabbade byarna, där depositionen av 137Cs var mellan 0.9 och 2.7 MBq/m2 (i Sverige fick vi som mest 200 kBq, dvs ca en faktor 5 mindre). Vid expeditionerna mättes helkroppsinnehållet av 137Cs hos frivilliga från några olika byar, och den årliga stråldosen till kroppen räknades ut. Det radioaktiva cesium som finns i kroppen har man fått i sig via maten.



Vi tog även urinprover från ett mindre antal människor, och mätte 137Cs koncentrationen i proverna hemma i labbet. Genom att jämföra cesiumnivån i urinproverna med cesiumnivån uppmätt i kroppen kunde vi fastställa relationen mellan kroppsinnehållet av cesium och utsöndringen. Då det kan vara krångligt och tidsödande att mäta direkt på människor kan urinprov vara ett alternativ till att uppskatta mängden radioaktivt cesium i kroppen, genom att man vet denna relation och då kan räkna ut kroppsinnehållet av cesium. Vi har utvärderat några olika metoder för att göra detta. Det finns dock stora osäkerheter i metoden att använda urinprov eftersom man gör antaganden om utsöndringen av cesium i urin som gäller för en ”medelmänniska” medan det i verkligheten är stora skillnader mellan olika människors metabolism av ämnet.



För att kunna mäta den stråldos invånarna i byarna fick från radioaktiva ämnen på mark, byggnader, träd etc, dvs extern bestrålning, så fick de en dosimeter som bars i ett snöre runt halsen under en månads tid, för att sedan skickas till Sverige för utvärdering. Dosimetern registrerade all strålning från omgivningarna, även naturlig strålning, och vi har utvärderat den del som kom från 137Cs som föll ned från Tjernobylolyckan. Även här finns stora osäkerheter då man räknar ut en stråldos till kroppen pga långa transport och väntetider (då dosimetern ej burits intill kroppen) då dosimetern registrerar strålning man egentligen inte är intresserad av. Cesium tränger med tiden längre ned i jorden vilket gör att strålningen från depositionen minskar med åren. Detta syns tydligt vid mätningar av externstrålningen med dosimetrar, stråldosen minskar med ca 15% per år mellan 1990 och 1998.



Dosbidraget som kommer från intern kontaminering av 137Cs minskar dock inte lika snabbt med tiden, och kan t.o.m öka vissa år. Detta beror i stor utsträckning på vad man äter. I byarna vi besökt äter man till stor del lokalt producerad föda, vilken kan innehålla en del radioaktivt cesium. Man har också en stark tradition att plocka svamp vilket gör att svamprika år ökar helkroppsinnehållet av 137Cs markant. Den dåliga ekonomiska situationen för många människor i Ryssland gör att det är svårt att förändra deras dietvanor, de är beroende av självhushållning. Den effektiva dosen från 137Cs i kroppen (intern bestrålning) är ca 30-50% av den totala effektiva dosen, dvs den från både intern och extern strålning. Den totala effektiva dosen från radioaktivt cesium efter Tjernobylolyckan var i medeltal mellan 1.2 och 2.5 mSv per år mellan 1991 och 1998. Stråldosen från naturlig bakgrundsstrålning är ca 2.4 mSv per år som ett världsmedelvärde. (Less)
Abstract
From 1990 to 1998, estimations of the effective dose from external as well as internal irradiation from 137Cs and 134Cs were carried out for inhabitants in rural villages in the Bryansk region, Russia, highly contaminated due to the Chernobyl accident in 1986. The villages were situated about 180 km from the Chernobyl power plant and the deposition of 137Cs was in the range 0.9-2.7 MBq m-2. Yearly expeditions were conducted in autumn by members of the Departments of Radiation Physics in Malmö and Göteborg, Institute of Radiation Hygiene, St. Petersburg, and the first years also the Norwegian Radiation Protection Authority. The dose levels and their change in time were investigated for various groups of the general public. The body burden... (More)
From 1990 to 1998, estimations of the effective dose from external as well as internal irradiation from 137Cs and 134Cs were carried out for inhabitants in rural villages in the Bryansk region, Russia, highly contaminated due to the Chernobyl accident in 1986. The villages were situated about 180 km from the Chernobyl power plant and the deposition of 137Cs was in the range 0.9-2.7 MBq m-2. Yearly expeditions were conducted in autumn by members of the Departments of Radiation Physics in Malmö and Göteborg, Institute of Radiation Hygiene, St. Petersburg, and the first years also the Norwegian Radiation Protection Authority. The dose levels and their change in time were investigated for various groups of the general public. The body burden of 137,134Cs, and hence, the effective dose, was estimated from measurements of the urinary concentration of caesium radionuclides, together with direct measurements of the body content using a portable detector. The effective dose from external irradiation was estimated from measurements with thermoluminescent (TL)-dosemeters worn by the participants during one month each year. In a special case study, the changes in biokinetics of 137Cs during pregnancy was investigated in a woman with an unintended intake of 137Cs via mushrooms from a highly contaminated forest in the area. During pregnancy there is an increased excretion of caesium resulting in a biological half-time of caesium which was 54% of the half-time before pregnancy. The ratio of the 137Cs concentration in breast milk (Bq L-1) to that in the mother’s body (Bq kg-1) was 15% one month after the child was born. The body burden of 137Cs in the Russian individuals calculated from the concentration of 137Cs in urine showed a good agreement with the body burden estimated from in vivo measurements in the same individuals. Normalisation of the caesium concentration in the urine samples by the use of potassium or creatinine excretion was found to introduce systematic differences as well as a larger spread in the calculated values of the 137Cs body burden as compared with calculations without normalisation, using the urinary concentration of 137Cs only. The yearly effective dose from external and internal irradiation to inhabitants in the Russian villages varied between 1.2 and 2.5 mSv as a mean for all villages studied between 1991 and 1998 and the internal effective dose was, on average, 30-50% of the total effective dose during that period. The effective dose from external irradiation decreased on average 15% per year, while the effective dose from internal irradiation varied, depending to a great extent on dietary habits and especially the availability of mushrooms. The cumulated effective dose for a 70-year period after the accident was calculated to be around 100 mSv with the assumption that the effective dose will decrease by only the physical decay of 137Cs (2% per year) after 1998. Individuals may receive considerably higher effective doses, up to 0.5 Sv during a life-time considering the large spread in dose values among individuals. (Less)
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author
opponent
  • Prof. Wöhni, Tor, Oslo
organization
publishing date
type
Thesis
publication status
published
subject
keywords
medicinsk instrumentering, tomografi, radiologi, Klinisk fysiologi, body burden, Effective dose, Cs-137, urinary excretion, Cs-134, biological half-time, Chernobyl, breast milk, Medicine (human and vertebrates), internal irradiation, external irradiation, TLD, Clinical physics, radiology, medical instrumentation, tomography, Medicin (människa och djur), Physics, Fysik
pages
50 pages
publisher
Department of Radiation Physics, Lund university
defense location
Lilla Aulan, medicinskt forskningscentrum, Ingång 59, Universitetssjukhuset MAS, Malmö
defense date
2000-12-15 10:15
external identifiers
  • Other:ISRN: LUNDFD6/NFRF--00/1014--SE, ISRN LUMEDW/MEMR--00/1014--SE
ISBN
91-7874-101-7
language
English
LU publication?
yes
id
25791e3e-88b9-465b-ac24-693f619f760e (old id 41105)
date added to LUP
2007-08-01 16:13:21
date last changed
2016-09-19 08:45:13
@misc{25791e3e-88b9-465b-ac24-693f619f760e,
  abstract     = {From 1990 to 1998, estimations of the effective dose from external as well as internal irradiation from 137Cs and 134Cs were carried out for inhabitants in rural villages in the Bryansk region, Russia, highly contaminated due to the Chernobyl accident in 1986. The villages were situated about 180 km from the Chernobyl power plant and the deposition of 137Cs was in the range 0.9-2.7 MBq m-2. Yearly expeditions were conducted in autumn by members of the Departments of Radiation Physics in Malmö and Göteborg, Institute of Radiation Hygiene, St. Petersburg, and the first years also the Norwegian Radiation Protection Authority. The dose levels and their change in time were investigated for various groups of the general public. The body burden of 137,134Cs, and hence, the effective dose, was estimated from measurements of the urinary concentration of caesium radionuclides, together with direct measurements of the body content using a portable detector. The effective dose from external irradiation was estimated from measurements with thermoluminescent (TL)-dosemeters worn by the participants during one month each year. In a special case study, the changes in biokinetics of 137Cs during pregnancy was investigated in a woman with an unintended intake of 137Cs via mushrooms from a highly contaminated forest in the area. During pregnancy there is an increased excretion of caesium resulting in a biological half-time of caesium which was 54% of the half-time before pregnancy. The ratio of the 137Cs concentration in breast milk (Bq L-1) to that in the mother’s body (Bq kg-1) was 15% one month after the child was born. The body burden of 137Cs in the Russian individuals calculated from the concentration of 137Cs in urine showed a good agreement with the body burden estimated from in vivo measurements in the same individuals. Normalisation of the caesium concentration in the urine samples by the use of potassium or creatinine excretion was found to introduce systematic differences as well as a larger spread in the calculated values of the 137Cs body burden as compared with calculations without normalisation, using the urinary concentration of 137Cs only. The yearly effective dose from external and internal irradiation to inhabitants in the Russian villages varied between 1.2 and 2.5 mSv as a mean for all villages studied between 1991 and 1998 and the internal effective dose was, on average, 30-50% of the total effective dose during that period. The effective dose from external irradiation decreased on average 15% per year, while the effective dose from internal irradiation varied, depending to a great extent on dietary habits and especially the availability of mushrooms. The cumulated effective dose for a 70-year period after the accident was calculated to be around 100 mSv with the assumption that the effective dose will decrease by only the physical decay of 137Cs (2% per year) after 1998. Individuals may receive considerably higher effective doses, up to 0.5 Sv during a life-time considering the large spread in dose values among individuals.},
  author       = {Thornberg, Charlotte},
  isbn         = {91-7874-101-7},
  keyword      = {medicinsk instrumentering,tomografi,radiologi,Klinisk fysiologi,body burden,Effective dose,Cs-137,urinary excretion,Cs-134,biological half-time,Chernobyl,breast milk,Medicine (human and vertebrates),internal irradiation,external irradiation,TLD,Clinical physics,radiology,medical instrumentation,tomography,Medicin (människa och djur),Physics,Fysik},
  language     = {eng},
  pages        = {50},
  publisher    = {ARRAY(0x7c4f528)},
  title        = {Irradiation of members of the general public from radioactive caesium following the Chernobyl reactor accident. Field studies in a highly contaminated area in the Bryansk region, Russia.},
  year         = {2000},
}