Protection of the environment from ionising radiation: ethical issues

The paper identifies some of the main ethical issues concerning the protection of the environment from radiation and suggests ways in which ethics can aid in developing a system of protection. After a presentation of background on ethical theory and environmental ethics, three main issues related to environmental protection are discussed: First, the question of valuing the environment and implications for the definition of harm and monetary valuation of environmental goods; second, difficulties with scientific uncertainty and applications of the precautionary principle; and third, issues concerned with the distribution of risk and its relevance for participation in decision-making. In summary, the paper argues that there are strong ethical grounds to provide for the protection of the environment and that, all other things being equal, there is no reason to treat ionising radiation differently to other environmental stressors.     

Modelling the propagation of effects of chronic exposure to ionising radiation from individuals to populations

This study evaluated the potential effect of ionising radiation on population growth using simple population models and parameter values derived from chronic exposure experiments in two invertebrate species with contrasting life-history strategies. In the earthworm Eisenia fetida, models predicted increasing delay in population growth with increasing gamma dose rate (up to 0.6 generation times at 11 mGy h(-1)). Population extinction was predicted at 43 mGy h(-1). In the microcrustacean Daphnia magna, models predicted increasing delay in population growth with increasing alpha dose rate (up to 0.8 generation times at 15.0 mGy h(-1)), only after two successive generations were exposed. The study examined population effects of changes in different individual endpoints (including survival, number of offspring produced and time to first reproduction). Models showed that the two species did not respond equally to equivalent levels of change, the fast growing daphnids being more susceptible to reduction in fecundity or delay in reproduction than the slow growing earthworms. This suggested that susceptibility of a population to ionising radiation cannot be considered independent of the species' life history.     

The ecological relevance of current approaches for environmental protection from exposure to ionising radiation

This paper discusses the current approaches to environmental protection from ionising radiation from an ecological perspective, highlighting the need to understand fully what we are trying to protect. Ecologically relevant endpoints for environmental protection are discussed along with the need to integrate protection from ionising radiation with the approaches adopted for non-radioactive contaminants. A possible integrated assessment approach is outlined.     

Derivation of hazardous doses for amphibians acutely exposed to ionising radiation

Derivation of effect benchmark values for each taxonomic group, which has been difficult due to lack of experimental effects data, is required for more adequate protection of the environment from ionising radiation. Estimation of effects doses from nuclear DNA mass and subsequent species sensitivity distribution (SSD) analysis were proposed as a method for such a derivation in acute irradiation situations for assumed nuclear accident scenarios. As a case study, 5% hazardous doses (HD₅s), at which only 5% of species are acutely affected at 50% or higher lethality, were estimated on a global scale. After nuclear DNA mass data were obtained from a database, 50% lethal doses (LD₅₀s) for 4.8 and 36% of the global Anura and Caudata species, respectively, were estimated by correlative equations between nuclear DNA mass and LD₅₀s. Differences between estimated and experimental LD₅₀s were within a factor of three. The HD₅s obtained by the SSD analysis of these estimated LD₅₀s data were 5.0 and 3.1 Gy for Anura and Caudata, respectively. This approach was also applied to the derivation of regional HD₅s. The respective HD₅s were 6.5 and 3.2 Gy for Anura and Caudata inhabiting Japan. This HD₅ value for the Japanese Anura was significantly higher than the global value, while Caudata had no significant difference in global and Japanese HD₅s. These results suggest that this approach is also useful for derivation of regional benchmark values, some of which are likely different from the global values.     

Natural radioactivity in refractory manufacturing plants and exposure of workers to ionising radiation

This paper shows the results of a survey carried out at some refractory manufacturing plants. During the first part of the survey, the concentration of natural radioactivity in raw materials and end-products, coming from four plants, was assessed. Several raw materials and, as a consequence, some end-products as well have shown activity concentrations exceeding a few hundreds of Bq kg⁻¹ of ²³⁸U and ²³²Th. In some important raw materials, such as bauxite and corundums, a remarkable radioactive disequilibrium was observed; this is probably due to the high temperature processes undergone by these materials. The second part of the survey focussed on the measurements of ambient equivalent dose rates, airborne dust concentrations and radon indoor. On the basis of results obtained, the effective dose for the standard worker was estimated. Two different types of refractory plants were investigated. Effective doses for both plants were lower than 1 mSv y⁻¹.     

Abundance and diversity of aquatic macroinvertebrate communities in lakes exposed to Chernobyl-derived ionising radiation

Littoral (lake shore) macroinvertebrate communities were studied in eight natural lakes affected by fallout from the Chernobyl accident. The lakes spanned a range in ¹³⁷Cs contamination from 100 to 15500 kBq m⁻² and estimated external dose rates ranged from 0.13 to 30.7 μGy h⁻¹. General linear models were used to assess whether abundance of individuals, taxon richness, Berger-Parker dominance and Shannon-Wiener diversity varied across the lakes. Step-wise multiple regressions were used to relate variation in total abundance, taxon richness, Berger-Parker dominance, Shannon-Wiener diversity, taxon richness within major groups of macroinvertebrates and abundance of the more common individual taxa to the measured environmental characteristics (conductivity, pH, total hardness and phosphate; lake area, lake maximum depth and total external dose) of the lakes. No evidence was found in this study that the ecological status of lake communities has been influenced by radioactive contamination from the Chernobyl accident. Indeed, the most contaminated lake, Glubokoye, contained the highest richness of aquatic invertebrates. Taxon richness in the eight study lakes varied from 22 (Svyatskoe #7) to 42 (Glubokoye) which spans a range typical for uncontaminated lakes in the region. Since ⁹⁰Sr is readily-absorbed by Mollusca, estimated dose rates to this group exceeded those for other invertebrate groups in two lakes (Perstok and Glubokoye). However this study found no association between mollusc diversity or abundance of individual snail species and variation between lakes in the external radiation dose. Indeed Glubokoye, the lake most contaminated by ⁹⁰Sr, had the highest richness of freshwater snails per sample (an average of 8.9 taxa per sample).     

Monitoring of radiation and radioactivity in the environment

This report lists the programs for monitoring radiation and radioactivity in the environment that are known to be in operation or to have been in operation recently. It is intended as a guide to be used when seeking information on the programs of other institutions. Sources of the data have been the literature and personal correspondence and discussions.The programs are divided into the categories of weapons test fallout, natural activity and environmental monitoring of releases from specific facilities. Where possible, the types of measurements being made are also listed. While the data are as up to date as possible the field is changing rapidly and there may be ommissions.     

An overview of the ERICA Integrated Approach to the assessment and management of environmental risks from ionising contaminants

The ERICA project (environmental risks from ionising contaminants: assessment and management, EC contract no. FI6R-CT-2004-508847) concluded with the publication of two main outputs: the ERICA Integrated Approach to the assessment and management of environmental risks from ionising radiation, of which also introduces the user to the second main output, the ERICA Tool, which is a software programme with supporting databases, that together with its associated help will guide users through the assessment process. More than 60 European scientists contributed to the ERICA Integrated Approach. In addition, a large number of experts, policy makers, and decision-makers in different areas have contributed views on the ERICA Integrated Approach and its associated Tool from the user's perspective, through participation in the End-Users Group set up under the ERICA project. Databases on transfer, dose conversion coefficients and radiation effects on biota have been developed specifically for the purpose of the Integrated Approach, and incorporated into, or interacting with, the Tool. Species sensitivity distributions of biological effects data have been performed and did not reveal, for chronic exposure, any statistical grounds for separation between terrestrial, marine and freshwater ecosystems in terms of species sensitivity to radiation; on the basis of such analysis a universal screening dose rate criterion of 10 microGy h(-1) incremental dose rate is suggested for exiting the assessment procedure while being confident that environmental risks are negligible. This criterion is used for the two first tiers (conservative assessment with limited data requirement and various possibilities of incorporating user-defined parameter values, including the screening dose rate criterion) of the assessment methodology. Exposure situations of concern are carried through a third tier, making use of all relevant databases and with a number of issues and options listed to support and guide decision-making. This article provides an overview to the ERICA Integrated Approach, whereas further articles of this special issue describe in-depth different vital aspects of the Integrated Approach.     

Adaptive response in frogs chronically exposed to low doses of ionizing radiation in the environment

Using the micronucleus assay, decreased levels of DNA damage were found after high dose ionizing radiation exposure of liver cells taken from frogs inhabiting a natural environment with above-background levels of ionizing radiation, compared to cells taken from frogs inhabiting background areas. The data obtained from a small number of animals suggest that stress present in the above-background environment could induce an adaptive response to ionizing radiation. This study did not reveal harmful effects of exposure to low levels of radioactivity. On the contrary, stress present in the above-background area may serve to enhance cellular defense mechanisms.     

Ethics, genetics and dynamics: an emerging systematic approach to radiation protection of the environment

There is now a general consensus of opinion that an explicit approach is necessary to demonstrate radiation protection of the environment, and that this approach needs to be developed in a systematic way. The framework that is emerging links ethical and moral issues (anthropocentric, biocentric, and ecocentric) to broad-based principles and objectives of environmental protection (sustainable development, maintaining biological diversity, and habitat protection) and then links these, in turn, to the needs of current environmental management practices, such as environmental exploitation, pollution control, and nature conservation. The relevance of this to radiation is that its effects (such as causing early mortality, morbidity, reduced reproductive success, as well as resulting in observable (scorable) cytogenetic damage) are those that may have a bearing on these same environmental management practices. The devise that would appear to be most useful to bridge the gap between our disparate data on radiation effects and the needs of environmental management, is that of adding to the concept of Reference Man in the shape of a small set of Reference Animals and Plants. This approach has now been adopted by the ICRP, adding new dynamics-the motive forces, both moral and physical-to the subject. The way is now clear for rapid progress to be made on a number of fronts.     

基于数量视角的耕地保护政策绩效评价

耕地保护政策的绩效评价是我国粮食安全及土地调控的重要课题。本文基于数量保护的视角,采用数据包络分析法(DataEnvelopment Analysis,简称DEA)评价了我国2000-2007年的耕地保护政策绩效,测度对象主要为耕地总量动态平衡、土地用途管制、耕地执法监管政策。研究结果显示,耕地保护政策在数量保护上具有总体效率高(2002年除外)、规模效率递增或保持、纯技术效率高的表征,但是,规模效率、纯技术效率与总体效率不能很好拟合且三项效率的综合具有分层性,只有耕地总量动态平衡达到了最佳产出。进而得出结论:2000-2007年,耕地保护政策取得了耕地总量平衡、耕地基本数量维持、建设占用耕地趋缓、耕地违法减少的显著效果,然而,耕地保护政策绩效的年度差异、政策时滞及体制等影响因素的复杂、投入和产出的部分饱和亦表明绩效的不充分。为促进我国耕地保护政策绩效的提升,提出强化土地利用总体规划作用、建立耕地保护责任制度等建议,并对进一步研究作了展望。     

Human–environment interactions: learning from the past

The analysis of palaeoenvironmental archives—sediments, archaeological remains, tree-rings, documents and instrumental records—is presented as a key element in the global scientific endeavour aimed at understanding human–environment interactions at the present day and in the future. The paper explains the need for the focus on palaeoenvironmental studies as a means of ‘learning from the past’, and presents the rationale and structure of the IGBP-PAGES Focus 5 programme ‘Past Ecosystem Processes and Human–Environment Interactions’. The past, as described through palaeoenvironmental studies, can yield information about pre-impact states, trajectories of recent change, causation, complex system behaviour, and provide the basis for developing and testing simulation models. Learning from the past in each of these epistemological categories is exemplified with published case-studies.     

Transfer and uptake of radium in a natural and in a technologically modified radiation environment

Differentiation in the geochemical transfer and uptake of the nuclides ²²⁸Ra and ²²⁶Ra is observed to give high nuclide activity ratios, of ²²⁸Ra to ²²⁶Ra, ranging from 20 to 200 in sediment humus collected from a river subject to pollution. Differentiation of this nature is also observed in the non-ionic non-dialysable fraction of the Ra activity in river water and may be attributed to preferential complexing of ²²⁸Ra relative to ²²⁶Ra. Biological uptake of the activities produces a similar effect. The ratios are higher in a natural radiation environment than in a technologically enhanced one, indicating the influence of nuclide availability.     

Arsenic contamination of the environment: a new perspective from central-east India

This paper reports a regional contamination of the environment in central-east India that does not share geology or boundary with the Bengal Delta Plain. About 30,000 people residing in 30 villages and towns are directly exposed to arsenic and more than 200,000 people are "at risk." Complete geographical extent of this contamination is being established, and this newly reported contaminated area could be quite large. This paper further reports that the mechanisms involved in arsenic mobilisation are complex and the two theories of arsenic mobilisation, i.e., pyrite oxidation and oxyhydroxides reduction, do not fully explain the high levels of arsenic contamination. This paper also proposes the "oxidation-reduction theory" for arsenic mobilisation where the arsenic originates from the arsenopyrite oxidation and the arsenic thus mobilised forms the minerals and gets reduced underground in favourable Eh conditions. The stoppage of water withdrawal from the contaminated sources did not result in lowering of arsenic levels as expected according to the heavy groundwater extraction theory (pyrite oxidation theory). Cases of arsenicosis in the region are on the rise and the switchover to less contaminated water has not reversed the arsenicosis progression in the affected persons even after 2 years. Surface water of the rivers is also being contaminated because of the probable dislocation of contaminated groundwater due to the heavy rains in monsoon season, which indicates that the river water could be a major carrier of arsenic in dissolved or adsorbed forms that may be a cause of contamination of the delta plains.     

Waste disposal and the recommendations of the International Commission on Radiological Protection – Challenges for radioecology and environmental radiation protection

The 2007 Recommendations of the International Commission on Radiological Protection (ICRP) represent a change from a process-based to an exposure-based approach, where exposure situations are categorised as planned, emergency, and existing exposure situations. Although the new Recommendations contain further changes based on, inter alia, scientific developments since the publication of the 1990 Recommendations, they overall represent more continuity than change – a notable exception being the direct consideration of environmental protection. The implications of the new Recommendations for radioactive waste management are fairly marginal, as earlier recommendations in this area are still considered valid. This communication provides a brief overview of the current ICRP system for radiological protection as applied to radioactive waste management, as well as an outlook including the possibility of using the developing ICRP system for management of environmental effects as an ‘alternative way of reasoning’ when building the safety case for a specific waste disposal concept.