Notification levels related to the control of radioactive discharges.

In relation to the management of elevated discharges of radioactive materials from the Paks Nuclear Power Plant, two different types of notification level are proposed. They relate to discharges which are above normal but below those associated with an emergency. The first is technically based (reference level) while the second (reporting level) is mainly based on considerations of public concern. The actions expected to be implemented if either of the levels is exceeded are summarized.

Validation of environmental transfer models and assessment of the effectiveness of countermeasures using data on (131)I releases from Chernobyl.

The studies undertaken by the (131)I Working Group, part of the International Atomic Energy Agency's EMRAS (Environmental Modelling for Radiation Safety) programme, were focused primarily on evaluating the predictive capability of environmental models. Particular emphasis was placed on applying models to evaluate the effectiveness of countermeasures.

Cost assessment of ventilation and averted dose due to radon in dwellings.

The inhalation dose due to radon and its progenies could be averted by ventilation in dwellings; however, on the other hand the increased ventilation augments the heating cost. Therefore a cost-benefit analysis could contribute to optimise the ventilation rate. In our current work we applied our former defined parameters of the optimising procedure to assess the optimised ventilation and radon concentration in dwellings with average parameters. To assess the inhalation dose rates the time-dependent concentrations of all the progenies were calculated in case of periodic and continuous ventilation as well, at three different radon entry rates (5, 10, 20kBqh(-1)). The optimal ventilation rates in case of continuous ventilation are 0.22, 0.40 and 0.66h(-1), respectively. By these conditions the optimal radon concentration takes 160-210Bqm(-3). According to the more detailed analysis the periodic ventilation gives, in general, a better solution than the continuous one. The Monte Carlo simulations provided a large uncertainty; therefore, before the practical application of the results the uncertainty should be decreased taken into account the local conditions.

Model testing using data on 131I released from Hanford.

The Hanford test scenario described an accidental release of 131I to the environment from the Hanford Purex Chemical Separations Plant in September 1963. Based on monitoring data collected after the release, this scenario was used by the Dose Reconstruction Working Group of BIOMASS to test models typically used in dose reconstructions. The primary exposure pathway in terms of contribution to human doses was ingestion of contaminated milk and vegetables. Predicted mean doses to the thyroid of reference individuals from ingestion of 131I ranged from 0.0001 to 0.8 mSv. For one location, predicted doses to the thyroids of two children with high milk consumption ranged from 0.006 to 2 mSv. The predicted deposition at any given location varied among participants by a factor of 5-80. The exercise provided an opportunity for comparison of assessment methods and conceptual approaches, testing model predictions against measurements, and identifying the most important contributors to uncertainty in the assessment result. Key factors affecting predictions included the approach to handling incomplete data, interpretation of input information, selection of parameter values, adjustment of models for site-specific conditions, and treatment of uncertainties.

Model testing using data on 137Cs from Chernobyl fallout in the Iput River catchment area of Russia.

Data collected for 10 years following the Chernobyl accident in 1986 have provided a unique opportunity to test the reliability of computer models for contamination of terrestrial and aquatic environments. The Iput River scenario was used by the Dose Reconstruction Working Group of the BIOMASS (Biosphere Modelling and Assessment Methods) programme. The test area was one of the most highly contaminated areas in Russia following the accident, with an average contamination density of 137Cs of 800,000 Bq m-2 and localized contamination up to 1,500,000 Bq m-2, and a variety of countermeasures that were implemented in the test area had to be considered in the modelling exercise. Difficulties encountered during the exercise included averaging of data to account for uneven contamination of the test area, simulating the downward migration and changes in bioavailability of 137Cs in soil, and modelling the effectiveness of countermeasures. The accuracy of model predictions is dependent at least in part on the experience and judgment of the participant in interpretation of input information, selection of parameter values, and treatment of uncertainties.

Angiotensin II and FCCP mobilizes calcium from different intracellular pools in adrenal glomerulosa cells; analysis of calcium fluxes.

The aim of the present study was to examine the effect of angiotensin II on the different pools of exchangeable Ca2+ in isolated rat adrenal glomerulosa cells. On the basis of steady state analysis of 45Ca exchange curves at least three kinetically distinct Ca2+ compartments are present in these cells. The most rapidly exchangeable compartment was regarded as Ca2+ loosely bound to the glycocalyx and the other compartments were considered to be intracellular Ca2+ pools. The effect of angiotensin II on different intracellular compartments was examined by adding the hormone at different phases of Ca2+ washout. Angiotensin increased the rate of 45Ca efflux within 1.5 min when added at the beginning of the washout. This effect, however, could not be detected when the hormone was added at the 30th min of washout, indicating that at least one hormone sensitive pool had lost most of its radioactivity by this time. In contrast to angiotensin II, the mitochondrial uncoupler FCCP mobilized almost the same quantity of 45Ca irrespective of the time of its addition during the washout. This latter finding suggests that this presumably mitochondrial Ca2+ pool has a slow rate of exchange and thus differs from the pool initially mobilized by angiotensin II. The initial Ca2+ mobilizing effect of angiotensin II was also observed in a Ca2+-free media which contained EGTA, indicating that this effect is not triggered by increased Ca2+ influx. In the present study we demonstrate in the intact glomerulosa cell that angiotensin II mobilizes Ca2+ from an intracellular Ca2+ store which appears to be distinct from the FCCP-sensitive store.

Clinicopathological studies of liver cirrhosis and hepatocellular carcinoma in a general hospital.

Clinicopathological studies of 181 patients with liver cirrhosis undergoing autopsy in the pathology department of a municipal hospital between 1973 and 1976 are reported. The main etiological types were alcoholic (25.4 per cent), HBsAg positive (14.9 per cent), and cryptogenic cirrhosis (54.7 per cent). Four patients had multifactorial and secondary biliary cirrhosis and one patient had congestive cirrhosis. The morphological characteristics of the condition and the age and sex distribution of the patients were analyzed in each etiological group. Hepatocellular carcinoma occurred in 28.7 per cent of the cases, most frequently in association with HBsAg positive cirrhosis. Hepatocellular atypia was significantly more frequent in HBsAg positive than in other etiological types of cirrhosis and significantly more frequent in cases associated with hepatocellular carcinoma than in those not associated with it.

Pharmacokinetic study in a phase I trial with an alkylating agent, diacetyldianhydrogalactitol (DADAG).

Diacetyldianhydrogalactitol (DADAG), a new alkylating hexitol derivative, was given in 30-min infusions for 5 consecutive days or as a single high-dose administration. The parent drug was eliminated in a biphasic manner, with a terminal half-life of 30-40 h. Dianhydrogalactitol (DAG), the main, pharmacologically active metabolite, appeared after a lag time of about 0.2-0.6 h. Its peak concentration was reached 1-2 h after termination of the infusion. The terminal elimination of DAG followed that of the parent compound. During the 5-day schedule slight accumulation was observed, and the plasma concentrations of both compounds approached the steady state. Over a dose range of 75-1050 mg/m2 the daily mean plasma concentrations of DADAG increased by only about 3-4 times. Dose-dependent expansions of the distribution volumes of the drug (Vc, V lambda, Vss) were observed. The behavior of DADAG and DAG in the body could be adequately described by a three-compartment open model. After equilibration the plasma levels of the parent compound and its metabolite were determined by the rate of return of DADAG from the peripheral compartment and its conversion to DAG.

Pharmacokinetics and toxicity of mitomycin C in rodents, given alone, in combination, or after induction of microsomal drug metabolism.

The pharmacokinetics of mitomycin (MMC) was studied in Wistar rats. Up to five half-lives, the plasma concentration-time curve was biphasic. The AUC changed linearly with increasing doses between 0.5 and 7.5 mg/kg, which corresponds to 0.2 and 3 times the LD50 value in rats. Most of the drug was metabolized, and only 1%-2% and 10%-15% of the dose was eliminated unchanged by biliary and urinary excretion, respectively. The AUC of MMC at the LD50 is slightly less than that reported for the human MTD. Inoculation of MMC together with 5-fluorouracil and doxorubicin did not change the terminal half-life of MMC but decreased the total body clearance and the volume of distribution. The lack of significant influence of phenobarbital and 3-methylcholanthrene pretreatment on the terminal elimination half-life suggests that microsomal drug-metabolizing enzymes inducible by these compounds do not play a decisive role in the in vivo biotransformation of MMC.

Relation between dose, plasma concentration and toxicity in a phase I trial using high dose intermittent administration of an alkylating agent, diacetyldianhydrogalactitol (DADAG).

Diacetyldianhydrogalactitol (DADAG), a new alkylating sugar alcohol derivative, was administered as single, 30-min infusions in doses ranging from 390 to 1200 mg/m2. The dose-limiting toxicity was myelosuppression. The median times to WBC nadir and regeneration were 16 and 21 days, and to platelet nadir and recovery 20 and 27, respectively. Nausea and vomiting occurred frequently and were of moderate severity. For phase II studies 900 mg/m2 DADAG given every 4-6 weeks is recommended. The area under the plasma concentration time curve (AUC) for DADAG did not increase in proportion with dose escalation; it changed only from 235.5 +/- 70.7 to 262.4 +/- 71.5 micrograms h ml-1 between doses of 690 and 1050 mg/m2. No correlations between the dose administered and the nadir values for haemoglobin concentration, WBC and platelet counts, or the number of episodes of vomiting were demonstrable in this dose range. Such an association was revealed, however, when the above biological variables were related to the individual AUC for DADAG.

The role of comparative pharmacokinetics in the planning of human dose escalation: the experience with diacetyldianhydrogalactitol.

The pharmacokinetics of diacetyldianhydrogalactitol (DADAG) was compared in mice, rats, and humans. The ratios of human therapeutic dose (ThD) to the LD10 were 8 and 5 in mice and rats, respectively. The ratios of the corresponding AUCs of DADAG were 20 and 17, whereas those of dianhydrogalactitol (DAG), the main, active metabolite of DADAG, were 8 in both species. The lower human-to-rodent ratio for DAG was due to the fact that twice as much DAG was formed in the animals. Other factors contributing to the larger AUC in man were the 3-5 times smaller distribution volume found in humans as well as the lower hexitol sensitivity of human bone marrow cells. We conclude that in addition to the distance between the AUCs of the LD10 and of the human starting dose, interspecies pharmacokinetic differences should also be considered in planning the rate of dose escalation.

Radiation hazard of coal-slags as building material in Tatabánya town (Hungary).

High concentrations of 226Ra (865-2,383 Bq kg(1)) were measured in the coal-slags, originated from the region of the settlement Tatabánya, Transdanubian Middle Mountains, Hungary. These slags are commonly used as building materials in this district. The external gamma dose rate was measured in 188 rooms at different heights above the floor. In 124 rooms with slags used for construction, the average absorbed dose rate was 296 nGy h(-1). In 10 apartments the average radon concentration was 502 Bq m(-3). In that case the estimated effective dose due to inhaled radon and its progeny and gamma radiation was 10.3 mSv y(-1).

Determination and use of the monetary values of the averted person-sievert for use in radiation protection decisions in Hungary.

The monetary value of the averted dose is a key element in the implementation of the optimization principle both in radiation praxis and intervention. The main concept of this principle is to select options so as to maintain exposures at a reasonable level. The feature of this concept is to look for the minimal total cost, i.e., the sum of the costs of protection and health detriment. In its publications, ICRP emphasized the need for developing models which also take into account the "subjective" aspects of health detriment in the optimization process, such as the perception of risk by individuals and the need to put more emphasis on equity in the distribution of individual doses. This paper proposes a modified alpha-value model based on CEPN's model (Centre d'Etude sur L'Evaluation de la Protection dans le Domaine Nucleaire) to put more emphasis on recently published considerations about the smaller effects of the portion of collective dose derived from small doses. The parameters of the monetary value of unit collective dose averted, which is a key element of this type of model, can be estimated by means of approaches like human capital (HC) and willingness to pay (WTP) from the point of view of economic theories. The present study summarizes the results achieved by WTP among the radiation specialists mainly from the Paks Nuclear Power Plant, Hungary. The aim of the effort was to determine the value of a statistical life and the monetary value of a unit person-sievert associated with averted occupational exposure due to ionizing radiation. To apply the WTP method, a questionnaire has been prepared on the basis of the one introduced by CEPN in the late 1990's. The investigations show that the value of US$6,200 person-Sv(-1) seems to be acceptable for the alphabase-value for the occupational situation in Hungary in 1999. WTP assessments should be applied with caution since the economic level of the country, the workplace surveyed, and the computational methods affect the results. In addition, achieving a high level safety culture must rely on international cooperation both from the theoretical and practical viewpoints, and international markets affect the associated costs. Therefore the monetary requirements cannot always be assessed solely on a national basis.

Transfer of 137Cs to milk and meat in Hungary from Chernobyl fallout with comparisons of worldwide fallout in the 1960s.

Transfer coefficients for 137Cs from the Chernobyl accident were determined for milk (Fm) and meat (Ff) of cows and sheep in Hungary. Fm and Ff for both cows and sheep fed forage harvested within 1 mo of the accident were lower than results reported for worldwide fallout from weapons tests. Forage harvested 60 d or later after the accident produced an Fm similar to results from feeding soluble 134Cs. The results are interpreted to indicate three distinct categories of Fm about 2.0 X 10(-3), 4.0 X 10(-3) and 1.4 X 10(-2) d L-1, respectively, for Chernobyl fallout, worldwide fallout and soluble Cs isotopes or 137Cs contained in plants from soil uptake.

Dynamic behavior of 110mAg in sheep tissues.

The transfer coefficient of 110mAg to a range of sheep tissues and its biological half-life in these tissues has been determined. Liver was shown to be the major site of 110mAg deposition and retention, with a transfer coefficient of Ff 7.1 d kg-1 and a biological half-life of 79 d. These results also suggest that previous estimates of the transfer of silver to muscle were too high, although further work would be required to confirm this. There is a need for accurate data which can be used to predict the transfer of 110mAg to food-producing animals.

A validation study for the transport of 134Cs to strawberry.

The paper presents results on model validation by field experiment for transport of 134Cs to strawberry. The transfer of 134Cs to herbaceous plants was investigated following a wet deposition after an acute release during 2000. Leaf-to-fruit, soil-to-fruit and direct fruit pathways were examined. The available meteorological and local soil information together with the experimental data were taken into account by the model RUVFRU. The processes are described by first order differential equations. In the case of foliar contamination scenarios measured and calculated results for fruit are in good agreement. However, the results of soil contamination scenarios provide large differences of up to three orders of magnitude between model predictions and experimental values for either fruit or other parts of the plant. The bias could be explained by the underestimation of the interception of the plant at the beginning of the season, in the soil contamination scenario. The model output permits prompt assessment of emergency situations and provides aid making decisions concerning mitigation of the consequences of the accident.

Concentration of 226Ra in Hungarian bottled mineral water.

Concentration of the radionuclide 226Ra was determined in almost every type of bottled mineral water commercially available in Hungary. Determination of the radon coming from the radium dissolved in the water was used for activity measurement. As the results show, the 226Ra concentrations exceed the level of 100 mBq l(-1) in six cases out of the 28 types of mineral water investigated. In one case 3 Bq l(-1) was measured, which provides 0.3 mSv year(-1) committed effective dose for adults in the case of a consumption rate of 1 l day(-1). In soft drinks produced from mineral water a concentration of 2.6 Bq l(-1) was determined, which means 1.4 mSv year(-1) effective dose in the age group 12-17 years in the case of permanent daily drinking of 1 l of these beverages.

Validation of 131I ecological transfer models and thyroid dose assessments using Chernobyl fallout data from the Plavsk district, Russia.

Within the project "Environmental Modelling for Radiation Safety" (EMRAS) organized by the IAEA in 2003 experimental data of (131)I measurements following the Chernobyl accident in the Plavsk district of Tula region, Russia were used to validate the calculations of some radioecological transfer models. Nine models participated in the inter-comparison. Levels of (137)Cs soil contamination in all the settlements and (131)I/(137)Cs isotopic ratios in the depositions in some locations were used as the main input information. 370 measurements of (131)I content in thyroid of townspeople and villagers, and 90 measurements of (131)I concentration in milk were used for validation of the model predictions. A remarkable improvement in models performance comparing with previous inter-comparison exercise was demonstrated. Predictions of the various models were within a factor of three relative to the observations, discrepancies between the estimates of average doses to thyroid produced by most participant not exceeded a factor of ten.