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Biomedical subjects

K G Ioannides

Publications and source records attributed to K G Ioannides.

At least 19 recordsLinked to original sources
PubMed2005

Variation in stakeholder opinion on countermeasures across Europe.

A compendium of agricultural countermeasures and rural waste disposal options has been compiled as part of the EC STRATEGY (Sustainable Restoration and Long-Term Management of Contaminated Rural, Urban and Industrial Ecosystems) project. The compendium was discussed by the FARMING (Food and Agriculture Restoration Management Involving Networked Groups) network of stakeholders during meetings of national panels in the UK, Finland, Belgium, Greece and France in 2002. Their preliminary feedback has been summarised in terms of whether an option is generally acceptable, unacceptable or only acceptable under specific circumstances. A considerable divergence of opinion between national panels was apparent for many of the options considered. This could be attributed to differences in geomorphology, climate, land management, infrastructure, consumer confidence, sociopolitical context and culture. Where consensus was reached between stakeholders it was generally for those countermeasures that provide public reassurance, sustain farming practices and minimise environmental impact. Furthermore, whilst there was general agreement that contaminated food should not enter the food chain, many of the options proposed for its subsequent management were not generally acceptable to stakeholders.

Agriculture↗
PubMed2005

Stakeholder involvement in nuclear crisis management in Greece.

The setting up of the Greek Stakeholders Group in the framework of the EC Food and Agriculture Restoration Management Involving Networked Groups (FARMING) project is described. The Group included members from more than 20 governmental and non-governmental organisations, having interest and/or responsibilities in the management of a crisis following a nuclear accident. The stakeholders, during their meetings in 2002, discussed the agricultural countermeasures and rural waste disposal options which have been compiled by the EC Sustainable Restoration and Long-Term Management of Contaminated Rural, Urban and Industrial Ecosystems (STRATEGY) project. All stakeholders agreed that the most preferable were those options that ensure public acceptance, minimise environmental impact and maintain farming practices and acceptable living and working conditions. Their views are synoptically presented along with the major conclusions from the stakeholders meetings regarding nuclear crisis management.

Agriculture↗
PubMed2005

Achievements, difficulties and future challenges for the FARMING network.

The EC FARMING network (Food and Agriculture Restoration Management Involving Networked Groups) was set up to bring together the many and diverse stakeholders who would be involved in intervention following wide scale radioactive contamination of the food chain, so that acceptable strategies can be developed for maintaining agricultural production and safe food supply. The network comprises stakeholder panels in the UK, Finland, Belgium, France and Greece that have met regularly since 2001 to debate, discuss and exchange opinion on the acceptability, constraints and impact of various countermeasure options and strategies. The objectives of this paper are to consolidate the main achievements of the FARMING project over the period 2000-2004, to highlight the various difficulties that were encountered and to discuss the challenges for engaging stakeholders in off-site emergency management and long-term rehabilitation in the future.

Agriculture↗
PubMed2004

Radon activity levels and effective doses in the Perama Cave, Greece.

An investigation of atmospheric radon levels in the Perama Cave, North-western Greece, has been carried out using CR-39 detectors. The detectors were placed at various locations along the guided cave pathway and exposed during different sampling periods. Mean concentrations amounting to 925 +/- 418 and 1,311 +/- 352 Bq m-3 were recorded in the summer and winter months, respectively. As the Perama Cave is one of the most popular in Greece, attracting more than 85,000 tourists per year, the quantification of effective doses to staff and visitors was an issue of importance. Doses less than 5.1 microSv per visit were calculated for tourists and around 1.8 mSv y-1 for seasonal guides, employed for periods of high visiting frequency. The annual exposure of permanent guides was estimated to fall between 3 and 10 mSv, which is the range of action levels recommended by the ICRP.

Air Pollutants↗
PubMed2003

Use of HPGe gamma-ray spectrometry to assess the isotopic compositiion of uranium in soils.

Gamma-ray spectrometry was used to determine uranium activity and investigate the presence of depleted uranium in soil samples collected from camping sites of the Greek expeditionary force in Kosovo. Assessment of 238U concentrations was based on measurements of the 63.3 keV and 92.38 keV emissions of its first daughter nuclide, 234Th. To determine the isotopic ratio of 238U/235U, secular equilibrium along the two radioactive series was first ensured and thereby the contribution of 235U under the 186 keV peak was deduced. The uranium activity in the samples varied from 48 to 112 Bq kg(-1), whereas the activity ratio of 238U/235U averaged 23.1+/-4.3.

Isotopes↗
PubMed2003

Effect of soil amendments on radiocesium transfer to alfalfa.

Greenhouse experiments were carried out to evaluate the effect of different soil-based countermeasures on radiocesium transfer to Medicago saliva (alfalfa) grown on artificially contaminated loamy-clayey soil. Various rates of potassium, ammonium, and Prussian Blue supplements were applied, and the uptake of radiocesium by control and treated alfalfa plants was monitored during four growth periods. Transfer factors ranging between 0.06 and 0.02 were determined for control plants. Application of potassium at rates higher than 0.1 meq per 100 g soil was found to suppress radiocesium uptake, the effect being more pronounced at increasing fertilization rates. On the contrary, soil treatment with ammonium enhanced the bio-accumulation of radiocesium, indicating that Cs+ ions, previously unavailable to plant roots, were released from soil particles. Prussian Blue supplements had practically no effect on soil-to-alfalfa transfer of the radionuclide.

Agriculture↗
PubMed2000

A survey of 222Rn concentrations in dwellings of the town of Metsovo in north-western Greece.

A radon survey has been carried out of indoor radon concentrations in dwellings located in the town of Metsovo, in north-western Greece. To measure indoor radon concentrations, CR-39 detectors were installed in randomly selected houses and were exposed for about 3 mo, during summer and winter. Gamma spectroscopy measurements of the soil's radium content also were performed. The indoor radon concentration levels varied from 17.6 to 750.4 Bq m(-3), while the radium concentration of soil varied from 4.9 to 97.1 Bq m(-3). Seasonal variation of the radon levels and the influence of house features and soil are discussed.

Air Pollution, Indoor↗
PubMed1999

Strontium-90 concentration measurements in human bones and teeth in Greece.

Strontium-90 concentration was measured in human bones and teeth collected in Greece during the period 1992-1996. One hundred and five bone samples, mainly cancellous bone, and 108 samples, taken from a total of 896 individual teeth were processed. Samples were classified according to the age and sex of the donors. Samples were chemically pre-treated according to a specially devised method to enable extraction of 90Y, at equilibrium with 90Sr in the original sample. Subsequently, 90Y beta activity was measured with a gas proportional counter. Radiostrontium concentration in bone samples showed small variations with respect to age or sex, with an average value of 30 mBq 90Sr/g Ca. However, 90Sr concentration measurements in teeth demonstrated a pronounced structure, which clearly reflects contamination from the 1960s atmospheric nuclear weapons tests and the more recent Chernobyl accident. This difference is attributed to the different histological structure of skeletal bones and teeth, the later consisting mainly of compact bone. An age-dependent model for radiostrontium concentration in human bones and teeth is developed which is able to successfully reproduce the experimental data. Through a fitting process, the model also yielded calcium turnover rates for compact bone, as a function of age, as well as an estimate of radiostrontium contamination of foodstuffs in Greece for the past four decades. The results obtained in this study indicate that radiostrontium environmental contamination which resulted from the atmospheric nuclear weapons tests in the 1960s, exceed by far that caused by the Chernobyl accident.

Adolescent↗
PubMed1996

Reduction of cesium concentration in ovine tissues following treatment with Prussian Blue labeled with 59Fe.

The effectiveness of Prussian Blue in reducing the radiocesium contamination in ovine tissues was investigated. Five ewes were fed 137Cs-contaminated wheat for 30 d. When the 137Cs concentration in milk had reached equilibrium, one animal, serving as the control, was slaughtered and the activity in its tissues was measured. Two ewes were offered daily 1 g of Prussian Blue labeled with 59Fe in the Fe(III) position, outside the complex anion. One week after the administration of Prussian Blue, these animals were slaughtered, 1 wk apart, and the level of 137Cs in their tissues was measured. Comparing the concentration of 137Cs in the blood and tissues of the Prussian Blue treated animals to the corresponding concentrations measured in the control, a considerable reduction in the radiocesium activity concentration is observed. However, 137Cs concentrations are maintained at non-zero (about 20%) values in the first 2 wk after the administration of Prussian Blue. This observation can be attributed to the fact that most of 137Cs binds to Prussian Blue in the animals' digestive tracts and the measured activity concentrations follow the elimination of cesium from tissues. Using a two-compartment mathematical model, we can predict the level of 137Cs in tissue, following the administration of Prussian Blue. Labeling Prussian Blue in the Fe(III)-position resulted in the measurement of a (2.4 +/- 0.02) % retention of Fe(III) in sheep.

Animals↗
PubMed1995

Ratios of transfer coefficients for radiocesium transport in ruminants.

A corollary of the multiple-compartment model for the transport of trace elements through animals was tested for cows, goats, and sheep. According to this corollary, for a given body "compartment" k of the animal (soft tissue, lung, liver, etc.), the ratio a(k) = f(k)/f(blood) of the transfer coefficients f, should exhibit similar values for physiologically similar animals. In order to verify this prediction, two experiments were performed at the Agricultural Research Station of Ioannina and at the facilities of Ria Pripyat in Pripyat, Ukraine. Eight animals in the first experiment and eighteen in the second were housed in individual pens and were artificially contaminated with a constant daily dose of radiocesium until equilibrium was reached. The animals were then sacrificed and transfer coefficients f(k) to twelve body "compartments" k were measured. These data were used to calculate the ratios a(k). The results were in accordance with predictions of the model and average values of a(k) were extracted for ruminants. It is concluded that these values may be employed for the prediction of animal contamination in any body compartment through the measurement of blood samples.

Animals↗
PubMed1994

Kinetics of radiocesium sorption in lake sediments.

The sorption of radiocesium (137Cs) in sediments sampled from Lake Pamvotis of Ioannina was studied in a laboratory simulation. In a series of experiments, the kinetics of 137Cs sorption and 137Cs distribution profiles in sediment cores were investigated. The results have shown that a significant percentage of 137Cs (35%) is adsorbed in the sediments during the first 3 d, at a rate of 0.41 +/- 0.05 d-1. The rest of 137Cs is adsorbed with the slower rate of 0.024 +/- 0.004 d-1. 137Cs rapidly reaches (< 5 d) a depth that does not exceed 3.5 cm. The sorption of 137Cs was found to follow Freundlich's empirical law, which describes the adsorption of most substances in solution to solids.

Adsorption↗
PubMed1993

Transport of radiocaesium from a sheep's diet to its tissues.

Transfer coefficients for radiocaesium transport from a sheep's diet to blood, muscle, lung, liver, kidney, spleen heart, brain, rumen, intestines and fat were measured in a controlled experiment involving 50 adult ewes. The animals were fed dry grass and wheat, both contaminated with Chernobyl fallout debris, for a period of 60 days. During this period half of the animals were killed at regular intervals and samples of their blood and tissues were measured for radiocaesium concentration. The rest of the animals were returned to uncontaminated food and were monitored for radiocaesium concentration through periodic slaughtering for an additional 60 days. Transfer coefficients were extracted from the plateau reached at the end of the contamination phase. The data were also analyzed by means of a recently proposed linear multiple compartment model and transport rate parameters for each compartment were extracted. Transfer coefficients computed through the model's transport rate parameters show remarkable agreement with the experimentally obtained values.

Animals↗
PubMed1993

Radiocaesium transfer to sheep's milk as a result of soil ingestion.

Soil ingestion as a source of radiocaesium contamination to ruminants was studied by measuring the transfer coefficient to sheep milk. Eight lactating ewes, housed in individual metabolism cages, were used. Fifty grams per day of heavily contaminated sandy topsoil, collected in 1990 from the Chernobyl area, were administered orally to the animals for a period of 1 week. The daily dose intake in 137Cs was 1835 Bq day-1. During this contamination period, daily milk production and excreta output were measured. The ewes were monitored for an additional 7 day decontamination period, while they fed on uncontaminated feed. Transfer coefficients were obtained through a best fit (minimum chi 2) of the data to predictions of a linear compartment model. The values obtained were fm = (2.6 +/- 0.7) x 10(-2) and f mu = (5 +/- 2) x 10(-2) days kg-1 for radiocaesium transport to milk and urine, respectively. These results suggest that soil ingestion can be a major source of radiocontamination for sheep and other free-grazing ruminants. Comparison of our results with soil-to-milk transfer coefficient values derived in two recent independent experiments suggests that there might be a strong dependence of radiocaesium availability on soil composition.

Animals↗
PubMed1991

Radioiodine retention in ovine thyroids in northwestern Greece following the reactor accident at Chernobyl.

Iodine-131 concentrations were measured throughout the summer of 1986 in thyroids of lambs slaughtered at Ioannina (Northwestern Greece) following the accident at the Chernobyl nuclear reactor. During the survey, 40 thyroids were collected. The highest level of 131I detected was 2471 +/- 339 Bq per thyroid. The thyroids of 20 lambs did not contain detectable 131I concentrations, while the contamination content of the others was greatly variable. The transport of 131I from pasture to thyroids of lambs has been described through a simple model for the retention of 131I in the glands. The transfer coefficient fT, expressing the steady-state equilibrium, was estimated to be 564 +/- 270 kg-1 d. This result reflects the sensitivity of animal thyroids as biological radioiodine monitors.

Accidents↗
PubMed1991

A general multiple-compartment model for the transport of trace elements through animals.

Multiple-compartment models employed in the analysis of trace element transport in animals are often based on linear differential equations which relate the rate of change of contaminant (or contaminant concentration) in each compartment to the amount of contaminant (or contaminant concentration) in every other compartment in the system. This has the serious disadvantage of mixing intrinsic physiological properties with the geometry of the animal. The basic equations on which the model presented here is developed are derived from the actual physical process under way and are capable of separating intrinsic physiological properties from geometry. It is thus expected that rate coefficients determined through this model will be applicable to a wider category of physiologically similar animals. A specific application of the model for the study of contamination of sheep--or indeed for any ruminant--is presented, and the temporal evolution of contaminant concentration in the various compartments of the animal is calculated. The application of this model to a system of compartments with changing geometry is also presented.

Animals↗
PubMed1989

A study of radiocesium contamination and decontamination of sheep's milk.

The radiocesium contamination and decontamination of sheep's milk were studied under a constant level of activity concentration in the sheep's diet. Two sets of experiments were performed: one at the end of the animal's lactating period and one during the main lactating period. The data were in satisfactory agreement with the predictions of a simple two-compartment model. At the stage of equilibrium the data yielded the transfer coefficient fm with an average value of fm = 0.063 +/- 0.005 d L-1. In the second experiment a detailed study of the decontamination phase revealed a two-component decay with amplitudes 53% and 43% and half-lives 1.5 d and 6.9 d, respectively. A small 4% long-lived (T1/2 = 170 d) third component could not be distinguished from an overall background decay, measured in control animals.

Animal Feed↗
PubMed1989

The propagation of the Chernobyl 131I impulse through the air- grass- animal- milk pathway in northwestern Greece.

A three-compartment (air- grass-milk) milk contamination model for 131I has been applied to atmospheric, grass and milk data, following the April 1986 nuclear accident at Chernobyl. Samples of ovine and bovine milk collected daily by a large dairy company in Ioannina (northwestern Greece), throughout the month of May 1986 have been employed. The contamination impulse in the area, which provides the input to the model, has been approximated by a first order gamma-variate curve. Transfer rates and decay constants have been extracted by fitting predictions of the model independently to each set of data (air, grass and milk). All model parameters obtained from more than one set of data show remarkable consistency. These parameters are used to calculate the transfer coefficients fm for the transport of radioiodine at equilibrium for sheep and cows.

Accidents↗