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Conséquences de l'irradiation des populations et des travailleurs

Objective

AS A RESULT OF THE CHERNOBYL REACTOR ACCIDENT ON 25 APRIL 1986, THERE WAS A RELEASE INTO THE ATMOSPHERE WHICH FOR SEVERAL DAYS AFFECTED THE DIFFERENT COUNTRIES OF EUROPE TO VARYING DEGREES.
THROUGH THE CONTAMINATION OF VARIOUS LINKS IN THE FOOD CHAIN (WATER, MILK, CHEESE, VEGETABLES, MEAT, FISH, ETC...), THIS ATMOSPHERIC RELEASE PRODUCED DOSES POTENTIALLY CAPABLE OF CAUSING HEALTH DAMAGE TO THE POPULATIONS EXPOSED.IN ORDER TO LIMIT THIS DAMAGE, CERTAIN COMMUNITY COUNTRIES TOOK A NUMBER OF COUNTERMEASURES IN THE FORM OF PROHIBITIONS, RESTRICTIONS OR GIVING ADVICE. GREECE, FOR EXAMPLE, BANNED THE SALE OF GREEN VEGETABLES AND SHEEPMEAT. ITALY FORBADE THE CONSUMPTION OF GREEN VEGETABLES AND ADVISED PREGNANT WOMEN AND CHILDREN UNDER THE AGE OF TEN NOT DRINK FRESH MILK. FRANCE PUT A BAN ON THE CONSUMPTION OF SPINACH IN THE EASTERN PART OF ITS TERRITORY AND BELGIUM ADVISED NOT TO ALLOW COWS OUT TO PASTURE. AS FOR SPAIN, IT SAW NO REASON TO DO ANYTHING AT ALL.
THESE EXAMPLES SHOW A WIDE VARIATION IN THE CHOICES OF ACTION TAKEN.THE DIFFERENCES CAN BE EXPLAINED IN PART BY THE DIFFERENCES IN THE RADIOACTIVITY LEVELSMEASURED IN EACH COUNTRY, BUT THESE INDICATORS ARE NOT ENOUGH TO EXPLAIN A POSTERIORI THE CHOICES MADE. IT APPEARS THATOTHER INDICATORS MUST HAVE BEEN INVOLVED IN AT LEAST ONE COUNTRY. IT IS POSSIBLE, FOR EXAMPLE TO CITE "OBJECTIVE" INDICATORS MORE PRECISE THAN THE MAXIMUM INFANT, CHILD OR ADULT DOSE, THE AVERAGE DOSE, THE COLLECTIVE DOSE, THE COST, ETC. OTHER, MORE SUBJECTIVE, INDICATORS, HAVE ALSO BEEN ABLE TO PLAY A ROLE, SUCH AS ANXIOUSNESS TO RESPOND TO PUBLIC CONCERN OR, CONVERSELY, THE PSYCHOLOGICAL IMPACT OF A BAN OR THE REFUSAL TO ATTACH TOO MUCH IMPORTANCE TO A RISK JUDGED TO BE NEGLIGIBLE.
A database has been expanded allowing the evaluation of sanitary consequences and of economical impacts of an accidental pollutant release.
The database covers all the countries of the European Community, on a grid 10,000 km{2}.
The parameters included concern population, land use, agricultural productions and employment.

Data files have been transferred to floppy disks and 2 software programs have been written. The first 1, devoted to internal use, introduces new data in the base and the second 1 assists the consultation of the database. This software is entirely conversational and allows the selection of a given data file, a country, 1 or several meshes and the meshes for which the value of the parameter is in a given range.

Data concerning the quantities of collected milk have been included in the database in the 10,000 km{2} grid. Data concerning water transfer are collected in the frame of the european CORINE project. This data concerns water abstraction (place, quantities) and water distribution (covered area, consumption for industrial, domestic and agricultural uses), both for surface and groundwater, in all the European countries. When available, this data will be included in the database.

The map of Europe and the grid have been computerised and discussions are in progress with respect to obtaining software able to assign the value of a parameter to a given mesh.

An expert system has been developed to provide a decision aiding system in case of contamination of foodstuffs after an accidental release of radionuclides. The objective of this system is to establish a classification of the countermeasures that can be envisaged, taking into account feasibility, dose reduction and economical consequences. This work will be developed to include the representation of parameters that are not easy to quantify: the influence of the quantity of contaminated products; the relations between public reactions and countermeasures.

A bibliographic synthesis concerning the internal contamination measurements performed in the European countries after the Chernobyl accident had been written.

In contrast to ionising radiation, chemical carcinogenic risk cannot be assessed with unifying assumptions on the underlying carcinogenic processes considering the diversity of the mechanisms of action, progress in comparison of detriments may be achieved using a case by case approach focussing, at first, on directly acting chemical compounds (ie not requiring metabolic activation) for which carcinogenicity is highly suspected in humans. The aim of a study on nonferrous metals was thus to discuss procedures for making extrapolation to humans based on a detailed analysis of experimental results. Toxicological profiles were established for nickel and cadmium inorganic derivatives (speciation) from updated literature. Animal data were standardised by making reference to the main recommendations of good laboratory practice (European Community (EC)) guidelines). Evaluation was performed using a scheme based on 3 critical parameters: study duration which should extent to the life expectancy of the species under study since most of malignancies occur naturally in the last third of the life span; sample size, the statistical significance of negative experiments being ascertained depending on sized of exposed and control groups and on spontaneous tumour incidence; survival rates of groups, since sufficient numbers of animals should be at risk during most of their life span (comparison of survival rates of exposed over controls and controls over historical series).

Animal carcinogenic bioassays relative to 9 nickel and 6 cadmium inorganic substances were reviewed. Experiments on inhalation demonstrate lung carcinogenicity of nickel subsulphide and of cadmium oxide,cadmium sulphide, cadmium sulphate and cadmium chloride in rats. For cadmium compounds, results were negative in mice and hamsters; no carcinogenic effects were observed following oral administration. For routes of less or no relevance for human risk assessment, some results were clearly positive (subcutaneous, i ntramuscular injection) demonstrating cancers in situ but not in remote sites for nickel substances. With respect to cadmium substances, systemic carcinogenic effects were noticed in testis and prostatic glands for soluble compounds. For both metals, numerous studies fail todemonstrate cadmium carcinogenicity, but methodology acceptable negative ones are very limited in number. Accordingly strain dependent effects and dose effect relationship could not be thoroughly assessed.

Detailed analysis of animal experiments does not confirm the unifying ion hypothesis proposed for assessing carcinogenic risk of metal inorganic compounds. For nickel, more results on relevant routes are needed. For cadmium, additional studies on interspecies differences are needed for a better understanding of extrapolation procedures.

Analysis of public attitudes toward nuclear energy shows the considerable importance of subjective components. As far as risk is concerned, fear and anxiety are not the only explicative factors, and both ideology and culture must be taken into account. Within a comparative approach the following are analysed:
the subjective dimensions of risk perception for activities, the nuclear one obviously but also others which are common in the everyday life;
the difference between risk perceptions of specialists and of lay people which can explain the difficulty in establishing a fruitful communication. The final goal is to propose methods or at least recommendations for integrating this subjectivity in risk management and more precisely in risk communication.

As part of a study of risk perception among specialists and of lay people a questionnaire has been prepared which addresses the following issues: the opinion on major hazards, the level of risk and its acceptability (as a willingness to do more for risk reduction) for various activities, and elicitation of criteria used by people when they manage the risk. The questionnaire has been proposed twice, firstly to 150 safety experts from various technical domains and secondly to a representative sample of lay people in the Bordeaux area (705 individuals). A first comparison has been made. Search for more experts (especially in nuclear and chemical domains) and in depth analysis will be pursued. Synthesis of concepts and approaches used in risk perception studies:
A review of the risk perception discipline has been written. It details the definitions of risk, the place of risk perception in risk analysis, the various approaches and dimensions used to describe the individual and social phenomenon of risk perception, and the tentative modelisations of attitudes toward risk.

A European database, EUROGRID, has been further developed to gather and organize the data necessary, in the cases of a radiation accident, to assess the consequences for the environment and population. Feasibility studies were also carried out with the aim of introducing new parameters into the grid concerning water resources and usage, a protection factor due to housing characteristics and exchanges of agricultural products between different meshes on the grid. Software has been developed for easy consultation of the database.

Software has also been developed for an expert system, DACFOOD, to enable decision markers to choose the most appropriate measures concerning foodstuffs for mitigation of the consequences of an accident. A preliminary study has also been carried out to identify those situations where decisions concerning agricultural productions need to be taken urgently during the early phase after an accident.

Risk perception of major hazards has been studied using a questionnaire, concerning 19 hazardous activities, given to 150 safety experts and 705 lay people. Both groups ranked most of the activities similarly. Large differences appeared only for ozone depletion, emphasized by the public and for domestic accidents and transport of dangerous materials, emphasized by the experts. For both groups perceptions of risks between pairs of hazards tended to be postively correlated, ie persons concerned about one hazard are more likely to be concerned about other hazards as well. The demand for more safety measures by the public was high.

Methods for estimating the economic consequences of major technological accidents, and their corresponding computer codes, have been applied to hypothetical scenarios for the interest of risk managers with a decision aiding perspective, and have been applied to actual accidents for comparison. The following results were obtained:
for large accidents the unit for cost is the billion;
costs of the 2 scenarios (hypothetical and actual) are of the same order of magnitude when side effects are not accounted for;
side effects are unavoidable in the long term;
cost estimates from codes are of value in emergency planning and for short term countermeasures associated with rapid recovery
environment recovery is costly and is neglected in codes.

Studies have been carried out to gain information on the transfer of radionuclides in the environment to man (migration in the soil, soil to plant and plant to animal transfer) and on possibilities of reducing it. A furnace, the Polyr furnace, was used for the production of aerosols to contaminate soils and plants. Sampling sites were initially chosen in France and data from other countries (Belgium, Germany, Spain, United Kingdom) will be added to the data bank. A study of the solubility of particles produced by POLYR found that caesium was almost always soluble, but strontium was not. Ruthenium was not soluble indicating ruthenium transfer factors are negligible, which is in accordance with post Chernobyl observations.

Decontamination of soils and surfaces after a nuclear accident was also considered. A technique of sowing turfing plants by hydroseeding and removing the vegetal carpet after growth has been developed. A machine for soil scrapping is being tested. Decontamination may be achieved by spraying the ground with an aqueous solution of some organic polymers which can stop resuspension and prevent runoff. The gel is brushed off and, in laboratory tests for strontium and caesium, decontamination efficiencies varied between 50 and 85% according to soil type.
Project 1

EVALUATION OF INDUSTRIAL IRRADIATION / EUROPEAN DATABASE

European Database: EUROGRID

EUROGRID provides data that are needed for the assessment of health consequences and economic impacts of large releases, either radioactive or chemical, within the European Community. Data are estimated for all the meshes of a European grid. The development of two software packages has been undertaken in 1990.

For 1991, it is expected to complete the data of the little meshes (for the moment available only for Great Britain), to add other parameters and informations relative to the distribution of food products between meshes.

Decision Aiding System in Case of Contaminated Foodstuffs: DACFOOD

The objective of DACFOOD is to provide a conversational tool which evaluates preferences into the set of possible actions about contaminated foodstuffs. This tool could be used profitably for the search for a more complete knowledge about the management of such a crisis situation. Different points of view are analyzed in countermeasure evaluation: effectiveness, feasibility, direct and indirect cost and international reglamentation. In its present form, the system provides a classification of possible countermeasures, according to cost benefit analysis, taking into account doses received by different groups of population. Other aspects (public reactions, local considerations) are more difficult to deal with. The emphasis is on the representation of these aspects, using an expert system.

The DACFOOD prototype will become operational in January 1991. A technical document will then be available; it will be used as a users' guide and it will lay the basis of future developments.

For 1991, a more extensive collaboration with other laboratories (namely TNO) is to be developed, with the objective of integrating the viewpoints of different potential decision makers, and of using it with diverse scenarios.

Project 2

EVALUATION OF OBJECTIVE DETRIMENT IN RELATION TO ECONOMICAL CONSIDERATIONS

Research on humans beings

Within a comparative approach, methods of evaluation of radiological and chemical detriments are analyzed for the highlighting of criteria presently used in regulatory policies. On one hand, directly acting chemicals for which carcinogenicity is highly suspected in humans, are considered. For these, procedures for extrapolation of risk from an animal carcinogenesis database to human are discussed, using a case by case approach focusing on speciation and relevance of administration routes. For the radiological detriment experimental results on plutonium compounds will be critically reviewed in 1990, toxicological profiles being established for the various physicochemical compounds from updated literature. The standardized animal database on chemical and radiological agents will be gathered for testing various alternative assumptions relative to the carcinogenic risk management in humans.

Research on vegetal species

Comparative genotoxicity for environmental factors

Tobacco has already been used, in situ or in the laboratory, to demonstrate genetic effects at low doses of natural and artificial radioactivity : existence of a plateau for the natural background that corresponds to a dose of 4 cGy per year ; a linear response from this dose rate up to the maximum dose rate experienced of 87.6 Gy per year.

These in situ studies have been completed by laboratory experiments for testing new methods and techniques in order to assess the genetic effects of particular contaminants of the atmospheric environment.

Project 3

SUBJECTIVE DIMENSIONS OF THE RADIOLOGICAL DETRIMENT

Within a comparative approach, the subjective dimensions of risk perception are analyzed by considering various hazardous activities and different groups of people. The final goal is to propose methods or at least recommendations for integrating this subjectivity in risk management and more precisely in risk communication.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Commissariat à l'Energie Atomique (CEA)
Address
Centre D'études De Fontenay-aux-roses 60-68 Avenue Du Général Leclerc
92265 Fontenay-aux-roses
France