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PubMed2005

Identifying optimal agricultural countermeasure strategies for a hypothetical contamination scenario using the strategy model.

A spatially implemented model designed to assist the identification of optimal countermeasure strategies for radioactively contaminated regions is described. Collective and individual ingestion doses for people within the affected area are estimated together with collective exported ingestion dose. A range of countermeasures are incorporated within the model, and environmental restrictions have been included as appropriate. The model evaluates the effectiveness of a given combination of countermeasures through a cost function which balances the benefit obtained through the reduction in dose with the cost of implementation. The optimal countermeasure strategy is the combination of individual countermeasures (and when and where they are implemented) which gives the lowest value of the cost function. The model outputs should not be considered as definitive solutions, rather as interactive inputs to the decision making process. As a demonstration the model has been applied to a hypothetical scenario in Cumbria (UK). This scenario considered a published nuclear power plant accident scenario with a total deposition of 1.7x10(14), 1.2x10(13), 2.8x10(10) and 5.3x10(9)Bq for Cs-137, Sr-90, Pu-239/240 and Am-241, respectively. The model predicts that if no remediation measures were implemented the resulting collective dose would be approximately 36 000 person-Sv (predominantly from 137Cs) over a 10-year period post-deposition. The optimal countermeasure strategy is predicted to avert approximately 33 000 person-Sv at a cost of approximately 160 million pounds. The optimal strategy comprises a mixture of ploughing, AFCF (ammonium-ferric hexacyano-ferrate) administration, potassium fertiliser application, clean feeding of livestock and food restrictions. The model recommends specific areas within the contaminated area and time periods where these measures should be implemented.

Agriculture↗
PubMed2000

Radiation doses to members of the public near to Sellafield, Cumbria, from liquid discharges 1952-98.

Liquid wastes containing low levels of radioactivity have been discharged to the Irish Sea from the nuclear fuel reprocessing site at Sellafield since operations began in the early 1950s, and monitoring of radioactivity in foodstuffs has been undertaken over many years. Based on the best available monitoring data, supplemented by modelled values where necessary, doses to local critical groups have been reassessed using the most recent dosimetry. Contemporary habits data have been used where available, again supplemented by assumed habits where necessary. During the 1950s and 1960s the highest doses were received by individuals consuming Cumbrian Porphyra as laverbread, and peak doses around 0.8 to 1.0 mSv year(-1) have been estimated. During the 1970s and 1980s the critical exposure group switched to consumers of local fish and shellfish, with peak doses possibly reaching 2.5 to 3.0 mSv year(-1). Latterly, doses to all marine-related groups have declined to less than 150 to 200 microSv year(-1). At all times, doses have been within the appropriate limits set for members of the public.

Environmental Exposure↗
PubMed1992

Birth defects in Norway by levels of external and food-based exposure to radiation from Chernobyl.

In Norway, external doses of radiation resulting from fallout from the Chernobyl nuclear accident were estimated from detailed measurements, including soil deposition patterns. Internal doses were estimated from measurements of radioactive cesium in meat and milk supplies. The doses were calculated as average monthly doses for each of 454 municipalities during 36 consecutive months after the accident in spring 1986. Prospectively collected data on all newborns listed in the Medical Birth Registry of Norway who were conceived in the period May 1983-April 1989 were used to assess possible dose-response relations between estimated external and food-based exposures and congenital malformations and some other conditions. A positive association was observed between total radiation dose (external plus food-based) and hydrocephaly, while a negative association was observed for Down's syndrome. However, an important conclusion of the study was that no associations were found for conditions previously reported to be associated with radiation, i.e., small head circumference, congenital cataracts, anencephaly, spina bifida, and low birth weight. Potential sources of bias, including exposure misclassification and incomplete ascertainment of cases, are discussed.

Abnormalities, Radiation-Induced↗
PubMed1978

Accidental ingestion of Tc-99m in breast milk by a 10-week-old child.

Ten weeks after the birth of her first child by Caesarian section, a 27-year-old woman was admitted for evaluation of a possible central nervous system lesion. Four hours after i.v. administration of 15 mCi of Tc-99m for a brain scan, the patient breast-fed her infant; then became concerned about the possibility of radioactivity in her breast milk. Total body gamma-ray measurements of the infant indicated ingestion of 82.5 muCi Tc-99m (corrected for effective T 1/2), while ingestion calculated from gamma-ray measurements of serial milk samples was 75.6 muCi. The single organ radiation dose for the thyroid as the critical organ was 300 mRad, whereas that to the total body was 12 mRad (values derived from 82.5 muCi determined by whole body counting). Had breast feeding been continued at 4-hr intervals, the total ingested activity would have been 94.8 muCi giving the infant a dose of 380 mRad to the thyroid and 16 mRad to the whole body. Had the feeding been given 1/2-hr after injection 726 muCi would have been ingested, increasing the dose by a factor of 10.

Accidents↗
PubMed1996

ECOSYS-87: model calculations of the activity in cattle meat related to deposition time and feeding regimes after a nuclear fallout.

The radioecological model ECOSYS-87 was used to evaluate the effect of countermeasures for reducing the ingestion dose by eating cattle meat after an accidental release of radioactive material. Calculations were performed using a database adapted to Swiss conditions for the case that (1) contaminated grass or hay is replaced by clean fodder; (2) the last 100 days before slaughter, taking place one year after an accident, only uncontaminated fodder is given; and (3) alternative feeding regimes are chosen. Seasonal effects were considered by doing all calculations for a deposition at each month of the year. Feeding uncontaminated forage 100 d before slaughter (case 2) proved to be the most effective countermeasure and reduced the integrated activity in meat by 90% to 99%. The effect of replacing contaminated grass (case 1) was less uniform and depended strongly on the time a deposition occurred. In this case the reduction was between 50% and 100% one year after deposition. The substitution of contaminated hay (case 1) was less effective compared to the substitution of grass. The choice of alternative feeding regimes (case 3) led to a reduction of the integrated activity of up to 40% one year after deposition. The present model calculations clearly reveal the importance of the seasonality and demonstrate the usefulness of such calculations as a basis for generating countermeasures in decision support systems.

Animal Feed↗
PubMed1995

The determination of low levels of radiocaesium and radioruthenium in foodstuffs.

The Ministry of Agriculture, Fisheries and Food (MAFF) has the responsibility for safeguarding the food supply from authorised and accidental releases of radioactivity to the environment. MAFF funds a radiological research programme to assist in the achievement of its objectives and has recognised that there is a continuing requirement to develop cost effective and sensitive analytical methods for the detection of very low levels of radioactivity in foodstuffs. High resolution gamma spectrometry is often the most appropriate analytical method for the determination of 103Ru, 106Ru, 134Cs and 137Cs but the detection limits for these radionuclides in bulk foodstuffs do not permit the acquisition of accurate data at very low levels. Beta counting techniques offer inherently higher sensitivities but the development of radiochemical separation techniques is essential to provide appropriate counting sources. A radiochemical separation method has been developed for the determination of radiocaesium and radioruthenium in 0.5 kg fresh wt samples of a variety of foodstuffs. The method was shown to be robust and specific and mean method recoveries of 75% were obtained for both radiocaesium and radioruthenium. MDA's for the 1000 min counts on a gas-flow proportional counter were determined to be 0.015 Bq/kg fresh wt for both 137Cs and 106Ru.

Cesium Radioisotopes↗
PubMed2004

Radiostrontium activity concentrations in milk in the republic of Croatia for 1961-2001 and dose assessment.

Results of systematic measurements of 90Sr activity concentrations in milk for the period 1961-2001 are summarized. An exponential decline of radioactivity followed the moratorium on atmospheric nuclear testing. The highest activity of 90Sr deposited by fallout, 1,060 Bq m(-2), was recorded in 1963, while the peak 90Sr activity concentration in milk, 1.42 +/- 0.17 Bq L(-1), was recorded in 1964. The values in year 2001 for fallout deposition and milk were 7.7 Bq m(-2) and 0.07 +/- 0.03 Bq L(-1), respectively. The reactor accident at Chernobyl caused higher 90Sr levels only in 1986. 90Sr fallout activity affects milk activity; the coefficient of correlation between 90Sr fallout activity and 90Sr activity concentrations in milk is 0.80. The transfer coefficient from fallout deposition to milk was estimated to be 2.5 x 10(-3) Bq y L(-1) per Bq m(-2). The dose incurred by milk consumption was estimated for the Croatian population, the annual collective effective dose in 2001 being approximately 2.0 person-Sv.

Adolescent↗
PubMed1991

Transfer of Chernobyl fallout radionuclides from feed to growing rabbits: cesium-137 balance.

Intake, excretion and retention of gamma-emitting radionuclides were assessed in male rabbits fed a radioactive pelleted diet (137Cs = 858 Bq kg-1 as fed) containing 40% dehydrated alfalfa meal contaminated by Chernobyl fallout. In order to evaluate radionuclide retention, an experiment was carried out on 33 animals as follows: nine rabbits were slaughtered at the beginning of the trial, six were fed a radioactive diet for 42 days, six a radioactive diet for 21 days, six a radioactive diet for 21 days and a normal diet (137Cs = 112 Bq kg-1 as fed) for the following 21 days and six a normal diet for 42 days. All the animals were housed in individual metabolism cages throughout the trial. All faeces and urine were collected and analyzed separately and live weight and feed intake were measured on a weekly basis. At the end of the trial all the animals were slaughtered and the activities of net body and muscles were determined. Cesium-137, 134Cs, 103Ru, 106Ru, 125Sb, 110mAg and 40K were measured by gamma spectroscopy. More than 85% of ingested cesium was excreted through faeces and urine (fecal much greater than urinary) and the retained 137Cs in the carcass of the more contaminated animals was only 3% of the total ingested. The concentration of total cesium in muscle reached a maximum value of 156 Bq kg-1, much lower than the EEC guideline (600 Bq kg-1), and the biological half-life for 137Cs was calculated to be 11 days. The feed-body accumulation factors were determined in net body and muscle.

Accidents↗
PubMed1989

Transfer of Chernobyl 134Cs and 137Cs in cows from silage to milk.

The transfer of Chernobyl Cs-134 and Cs-137 to milk in dairy cows from a diet, predominated by silage, was studied under normal farming conditions. The study was carried out in the period December 1986 till August 1987 and comprised three periods with different levels of radioactive contamination of the silage. Transfer coefficients for both radionuclides were derived from measured radiocaesium concentrations in the diet components and in mixed milk samples. Average silage intake was calculated on basis of total need which depends on milk production. The transfer coefficients calculated for Cs-134 and Cs-137 after a 6 weeks feeding period of high-level post-Chernobyl silage were 0.26 and 0.27% d/l, respectively. These results indicate that a transfer coefficient of 1.2% d/l, from tracer and fallout studies and recommended for predictive purposes, is a conservative estimate in view of the post-Chernobyl experience. The transfer of caesium isotopes from silage to milk in dairy cows is dynamically described with a simple two-compartment model of Pelletier and Voilleque. The most important choices of parameter values to be made in matching calculated and measured concentrations in milk, are those for F and u/m. F is the fraction of ingested activity that is excreted in milk plus urine, and u/m is the ratio between the transfer rates to urine and milk, respectively. The study was carried out with financial support from the Dutch Ministry of Agriculture and Fishery.

Accidents↗
PubMed2002

Studies of strontium biokinetics in humans. Part 2: uptake of strontium from aqueous solutions and labelled foodstuffs.

The accidental release of radioactive isotopes of strontium, mainly (90)Sr, into the environment and its transfer into the biosphere results in an internal radiation exposure of the affected population. In order to obtain reliable estimates of the committed dose due to an intake of Sr radionuclides, reliable information on its metabolic behaviour inside the human body is needed, i.e. biokinetic data on fractional uptake from contaminated foodstuffs, distribution to and retention in different organs and tissues of the human body. Such information can be obtained by tracer kinetic investigations. The committed effective dose is dependent on the fractional intestinal absorption of the ingested activity (f(1) value). The International Commission on Radiological Protection in its publication ICRP 67 adopted an f(1) value of 0.3 for adults. This study is aimed at investigating if the value corresponds with the actual uptake from contaminated foodstuffs. Aqueous solutions and contaminated vegetables, i.e. cress and salad (lettuce) were used as test materials. For this purpose, the methodology for intrinsic labelling of foodstuffs described in part 1 was applied. For aqueous solutions, a mean f(1) value of 0.63+/-0.14 (mean +/- SD) was obtained by administering 1 mg of strontium. The uptake of Sr from cress intrinsically labelled with about 1 mg Sr almost corresponds to that from aqueous solutions (f(1)=0.62+/-0.10), but from lettuce it is reduced by a factor of 2 (f(1)=0.27+/-0.08).

Adult↗
PubMed1982

The identification of critical groups and its application to fish and shellfish consumers in the coastal area of the North-East Irish Sea.

Control of radioactive waste disposal to the environment, based on the recommendations of the International Commission on Radiological Protection (ICRP), necessitates an identification of the critical group of members of the public exposed from a given practice. Criteria for identification of critical groups based mainly on ICRP recommendations are discussed. Methods existing up to 1974 are briefly reviewed in the light of these criteria. Two more recent methods are described and compared on the basis of previous data; these methods, which are complementary, are based on homogeneity considerations and satisfy the criteria generally rather better than do the earlier methods. The application of the newer techniques to recent surveys of fish and shellfish consumption in the coastal area of the North-East Irish Sea is described, in relation to discharges from the Windscale reprocessing plant. The results of this survey are presented, and estimates are given of the effective dose equivalent to members of these critical groups in recent years, to show the effect of liquid discharges from Windscale in terms of public radiation exposure.

Animals↗
PubMed1984

Models for the transfer of radionuclides in cattle for use in radiological assessments.

In performing assessments of the radiological impact of releases of radioactive materials to the environment, mathematical models are required to enable the transfer through various parts of the environment and hence the dose to man to be predicted. The nature of the models and their degree of complexity depend largely upon the particular applications in which they are to be used. Two types of model of differing degrees of complexity for predicting the transfer of strontium, caesium and iodine in cattle have been developed at NRPB . They form part of a general model for the transfer of radionuclides through terrestrial foodchains . The first is a relatively simple model based on the use of equilibrium transfer factors, while the second is an improved but more complex model which incorporates the extra features necessary to provide a reasonable representation of the time dependence of transfer to milk and to meat. Comparisons of the results using the two types of model in some situations of radiological interest have been performed. From these comparisons conclusions have been drawn about the adequacy and pertinence of the use of each model type in different situations.

Animals↗
PubMed1988

Comparative uptake of U and Th by native plants at a U production site.

During a 3- to 4-year period, concentrations of 238U, 234U, 230Th, 232Th and 228Th were determined in soils and native vegetation at various sites around a typical U mining and milling operation in Wyoming. Plant/soil concentration ratios (CR) for U and Th isotopes were estimated for (1) exposed, weathered tailings, (2) the edge of a tailings impoundment, (3) an area downwind from exposed tailings, (4) a reclamation area and (5) several background, native range locations. The 238U/234U concentration ratio of 0.9 to 1.1 in soil and vegetation indicated near-radioactive equilibrium of both radionuclides at all locations. Mean concentrations of the U and Th isotopes in background soil ranged from 44 to 52 mBq g-1. Concentrations of 238U and 230Th in soil and vegetation were elevated above background at all sites disturbed by mining and milling activities. Uranium concentrations in tailings and invading vegetation were an order of magnitude greater than in the background locations, whereas 230Th concentrations were elevated above background by some two orders of magnitude. No demonstrable differences in radionuclide concentrations between plant groups and collection years were found. The observed CR values for 238U and 230Th of 0.81 and 0.69 for vegetation growing on exposed tailings were elevated above native range by factors of 9.0 and 3.6, respectively, and generally higher than other published values. Exceptionally high CR values for 230Th (1.9-2.9) observed near the tailings impoundment demonstrate that under certain conditions, vegetation can accumulate 230Th to a much greater extent than previously reported. Vegetation concentrations were lower for 232Th relative to 230Th and 228Th at locations where they are present at similar soil concentrations.

Colorado↗
PubMed1994

A rapid method for the determination of radioactive caesium in live animals and carcasses, and its practical application in Norway after the Chernobyl nuclear reactor accident.

A technique was developed for the measurement of levels of caesium radionuclides (137Cs + 134Cs) in live reindeer, cattle, and sheep and in carcasses from these species. The instrument used was a sodium iodide scintillation detector coupled to a portable multi-channel analyser. Based on a combination of background measurements and measurements of impulses from animals with the detector in different anatomical positions we recommend the following procedures: LAMB: The detector placed on os sacrum (standing animal). REINDEER: The detector placed between the hind legs (animal lying on its side). CATTLE: The detector placed on the back of the standing animal, midway between os sacrum and trochanter major. Average geometrical factors for live animals were estimated. It was a linear correlation between measured activity levels in meat samples and counted impulses per sec in live animals. Geometrical factors were estimated at 95% confidence level with uncertainty between 6-14%. The detection limits varied between 50-200 Bq (becquerel)/kg in areas with ground depositions between 5-200 kBq/m2. Since the winter 1986/87 the technique has been the standard procedure for monitoring slaughter animals and carcasses for radiocaesium activity concentrations.

Animals↗
PubMed2004

Development and application of Marinelli beaker standards for monitoring radioactivity in Dairy-Products by gamma-ray spectrometry.

Marinelli (reentrant) beakers are recommended for measurement of low-activity radioactive environmental samples, in both liquid and solid phase. The preparation of Marinelli beaker standards of milk powder containing 232ThO2 at secular equilibrium with its daughter radionuclides was studied. Standards were prepared by mixing of known amounts of solid ThO2 and milk powder. The densities of the standards were 0.5-0.7 kg dm(-3). Measurements of calibrated Marinelli beaker standards with HPGe detector showed that the energy dependence of the efficiency is similar to that of a point source, i.e. an almost linear dependence of log-efficiency vs. log-energy in the 200-2000 keV range, however the parabolic correlation fits better. The validity of these standards was checked by comparison with certified standard reference material IAEA-152-Milk powder containing radiocesium and radiopotassium. The results obtained were found to be in a good agreement with the published certified data. The limit of detection for the determination of radiocesium by gamma ray spectrometry under the prevailing experimental conditions is 0.03 Bq (i.e. 0.8 pCi), for samples of dairy products having lower densities of 0.7 kg dm(-1).

Dairy Products↗
PubMed2001

Practical improvement of the radiological quality of milk produced by peasant farmers in the territories of Belarus contaminated by the Chernobyl accident. The ETHOS project.

The Chernobyl post-accident situation has highlighted how the sudden emergence of persistent radioactive contamination in the environment is severely affecting the quality of life of the inhabitants in the concerned territories. The management of this situation is complex, mainly conditioned by the ability of the inhabitants themselves to be directly involved in the process of improving their living conditions. In this process, quality of life cannot be restricted solely to the dimension of radiological risk, but needs to encompass the diverse aspects of daily living, including the social, psychological, economic, political and ethical aspects. This paper presents the experience of the involvement of a group of peasant farmers from a village in the Republic of Belarus, in the process of improving the radiological quality of privately produced milk. This experience took place in the context of the ETHOS project, funded by the radiation protection research programme of the European Commission. The principal objective was to implement a complementary approach to the rehabilitation strategies adopted so far in the contaminated territories of the Republic of Belarus. This paper retraces the process of involvement of the inhabitants in a working group. It describes the characterisation of the situation by local actors, the opening of new possible actions to improve the radiological quality of milk at the individual level and the positive consequences at the scale of the village. The ETHOS project also illustrates how the scientific knowledge accumulated over many years since the Chernobyl accident in the field of radiation protection and radioecology can enter into local practices in the form of practical tools, which can be used by the population to produce significant improvements in the radiological situation.

Agriculture↗
PubMedDate not supplied

[Radioactive waste monitored around the city hospitals in Brescia. Results of a radiometric survey and model of the radiologic impact on the environment].

The release into environment of liquid radioactive wastes coming from the metabolic therapy department of the Spedali Civili in Brescia was monitored during six months, with a rate of release of about 20 divided by 50 mCi of 131I every 30 divided by 40 days. Samples of 10 liters of liquid, taken from sewers downstream from the release point during a release operation, was percolated on 50 cm3 of ionic exchange resin in order to achieve a suitable counting rate with a Ge(Li) crystal spectrometer, connected to a 2048 channel analyzer. From these measurements a dilution curve along the sewers course was obtained, allowing one to know, for a given radioiodine concentration at the release point, concentration at every point downstream. In this way, by means of a simple linear compartmental model, it is possible to calculate the average individual dose taken by individuals who are living in the region (250.000 inhabitants) in one year of release operations. In our case we considered, as critical pathways to man, cow milk, meat, cereals and fruits: we obtained for thyroid, which in the case of radioiodine is the critical organ, an individual annual dose of 5,41 x 10(-4) mrem, while for total body we obtained 9,49 x 10(-7) mrem.

Environmental Pollution↗
PubMed1987

Pathway: a dynamic food-chain model to predict radionuclide ingestion after fallout deposition.

This manuscript describes the structure and basis for parameter values of a computerized food-chain transport model for radionuclides. The model, called "PATHWAY," estimates the time-integrated ingestion intake by humans of 20 radionuclides after a single deposition from the atmosphere to the landscape. The model solves a set of linear, coupled differential equations to estimate the inventories and concentrations of radionuclides in soil, vegetation, animal tissues and animal products as a function of time following deposition. Dynamic processes in the model include foliar interception, weathering and absorption; plant growth, uptake, harvest and senescence; soil resuspension, percolation, leaching and tillage; radioactive decay; and livestock ingestion, absorption and excretion. Human dietary data are included to permit calculation of time-dependent radionuclide ingestion rates, which are then numerically integrated. The model considers seasonal changes in the biomass of vegetation and animal diets, as well as specific plowing and crop-harvest dates; thus the integrated radionuclide intakes by humans are dependent on the seasonal timing of deposition. The agricultural data base represents the arid and semi-arid regions of the western United States. The foliar deposition parameters apply to regional fallout out to a few hundred miles from nuclear detonations at the Nevada Test Site. With modification, the model could be applied to chronic or other acute releases, providing the ground deposition in Bq m-2 could be estimated. The output of PATHWAY (Bq ingested per Bq m-2 deposited) may be multiplied by the deposition and a dose conversion factor (Gy Bq-1) to yield an organ-specific dose estimate. The model may be run deterministically to yield single estimates or stochastically ("Monte-Carlo" mode) to provide distributional output that reflects uncertainty in the output due to uncertainty in parameters. Tests of the predictive accuracy are briefly described and work published to date on validation trials is cited.

Animals↗