Radiological protection, radioecology, and the protection of animals in high-dose exposure situations.

Although much consideration has been given to the subject of 'protection of the environment' in recent years, this has largely been driven by the desire to protect the natural environment, focused on the needs to maintain biological diversity, the conservation of species, and so on. The numerical values developed to help achieve these aims have therefore been aimed at protecting animals at the population level. But recent experiences with large scale nuclear accidents, and the seemingly growing threat of acts of terrorism or worse, draw attention to the needs to consider in more detail the radiological protection of animals under high-dose exposure situations, and in the context of urban and agricultural environments rather than natural ones. The concerns here are also quite different - essentially those of animal welfare, at an individual, not a population, level. So now that the International Commission on Radiological Protection has embraced the need to consider protection of the animal as patient in veterinary medicine, it is worth considering a number of possible implications for responding to such environmental exposure situations, such as ethical drivers, dosimetric modelling, categorisation of radiation effects, and the need for numerical guidance. All of these issues are briefly discussed.

Radiological protection of the patient in veterinary medicine and the role of ICRP.

At the request of the Main Commission of the International Commission on Radiological Protection (ICRP), Task Group 107 (TG107) was set up to consider the issue of radiological protection of the patient in veterinary medicine. TG107, who authored this article, brought together information relating to the use of diagnostic imaging and radiation oncology in veterinary medicine. A number of specific areas were identified that appeared to be appropriate for attention by ICRP. These included the use of dose quantities and units, the need for re-evaluation of stochastic and deterministic risks from ionising radiation in animals, and the growing use of imaging and therapeutic equipment for animals that is little different from that available to humans. TG107 unanimously recommended that it was both appropriate and timely for ICRP to consider and advise on these issues, and the Main Commission agreed. This paper summarises the findings of TG107.

Radiological protection and the exposure of animals as patients in veterinary medicine.

It is apparent that most of the techniques that make use of ionising radiation in human medical practices are now being applied in veterinary medicine. Steps are being taken by the IAEA to provide guidance for humans involved in such practices, but there appears to be no international initiative that considers the protection or welfare of the animal as a patient. There is therefore a risk that the deliberate exposure of an animal, particularly in the therapeutic application of radiation, could do more harm than good. In the light of recent developments in dosimetric modelling and the application of known effects of radiation on different types of animals, for the purposes of the protection of biota in an environmental context, it is argued that it would be sensible now to start a serious consideration of this issue. Some suggestions are made with regard to a number of areas that could be considered further, both specifically and with regard to the field of radiological protection as a whole.

ICRP's approach to protection of the living environment under different exposure situations.

The International Commission on Radiological Protection's (ICRP) system to protect the living components of the environment is designed to provide a broad and practical framework across all exposure situations. The objectives of ICRP are therefore also set in fairly broad terms, recognising that national and local environmental protection requirements may need to be set within them. The framework recognises the need to be able to demonstrate an adequate level of protection in relation to planned exposure situations, whilst also providing an ability to manage existing situations and accidents, as well as emergency situations, in a rational way. The objects of protection are always real biota in real exposure situations, and the scientific basis for their protection needs to be based on data originating from studies on the relationships between exposure and dose, dose and effects, and effects and consequences in real animals and plants. The framework that has been developed has therefore had to take such realities into account to make the optimum use of the data currently available, whilst being sufficiently flexible to accommodate new scientific information as it arises without having to alter the framework as a whole.

ICRP Publication 124: Protection of the Environment under Different Exposure Situations.

In this report, the Commission describes its framework for protection of the environment and how it should be applied within the Commission's system of protection. The report expands upon its objectives in relation to protection of the environment, in so far as it relates to the protection of animals and plants (biota) in their natural environment, and how these can be met by the use of Reference Animals and Plants (RAPs); their Derived Consideration Reference Levels (DCRLs), which relate radiation effects to doses over and above their normal local background natural radiation levels; and different potential pathways of exposure. The report explains the different types of exposure situations to which its recommendations apply; the key principles that are relevant to protection of the environment; and hence how reference values based on the use of DCRLs can be used to inform on the appropriate level of effort relevant to different exposure situations. Further recommendations are made with regard to how the Commission's recommendations can be implemented to satisfy different forms of environmental protection objectives, which may require the use of representative organisms specific to a site, and how these may be compared with the reference values. Additional information is also given with regard to, in particular, communication with other interested parties and stakeholders. Issues that may arise in relation to compliance are also discussed, and the final chapter discusses the overall implications of the Commission's work in this area to date. Appendices A and B provide some numerical information relating to the RAPs. Annex C considers various existing types of environmental protection legislation currently in place in relation to large industrial sites and practices, and the various ways in which wildlife are protected from various threats arising from such sites.

Radiation and protection of the environment: the work of Committee 5.

The development of a systematic approach to protection of the environment has required a number of basic steps to be taken, including a discussion of what objectives could reasonably be set, together with an examination of how existing knowledge could best be used in order to achieve them. It has required bold decisions to be made, new modelling to be undertaken, and new data sets to be compiled. Equally challenging, however, has been the need to fold the entire subject area into an expanded system originally developed for the protection of human beings. There are, inevitably, a number of data gaps, and further decisions need to be made. However, the priority now is to examine how this approach to protection of the environment can be used in practice. With an intensifying worldwide debate about the environmental merits of different forms of energy production, it would seem imperative that the various practices involved in the nuclear fuel cycle are able to demonstrate, clearly and independently, their own actual or potential impact on the environment. The International Commission on Radiological Protection now has the basic means for such evaluations to be made, and further developments in this system will reflect the experience of its practical application.

Clarifying and simplifying the management of environmental exposures under different exposure situations.

The International Commission on Radiological Protection recognises three different exposure situations: planned, existing, and emergency. In all three situations, the release of radionuclides into the natural environment leads to exposures of non-human species, as well as having the potential for exposures of the general public. Each release may therefore need separate evaluations of these two consequences in order to clarify the relevant objectives of protection, their compliance with various legal requirements, and how these objectives can be achieved. However, the need to meet more than one objective should not necessarily lead to a more complicated regulatory system. Indeed, with regard to low-level routine discharges from most nuclear plants, there would appear to be scope for simplifying the entire system, to protect both humans and biota, by using discharge consent and specified radionuclide environmental quality standards for water, soil, and air in a manner similar to that used to regulate other major, non-nuclear industries. In contrast, different objectives for humans and the environment need to be set and evaluated independently for existing exposure situations. For emergency situations, the separate consequences of different management options for humans and the environment should be made clear. Should an emergency occur, it is important to have meaningful environmental criteria in order to communicate clearly with the public at large as events unfold.

Radioecology, radiobiology, and radiological protection: frameworks and fractures.

A framework for the protection of the general public has been in existence for a very long time, although steps have recently been made by the ICRP to ensure that it is more fully comprehensive with regard to all actual and potential exposure situations. Protection of the environment, however, has only recently begun to be addressed in a structured manner, and is still an evolving subject. Nevertheless, it needs to be centred around some form of parallel framework to that which has evolved for the protection of human beings, although clearly on a different scale. It also needs to be embedded within the basic science of radiobiology, and form a central part of radioecology.

Scope of radiological protection control measures.

In this report, the Commission recommends approaches to national authorities for their definition of the scope of radiological protection control measures through regulations, by using its principles of justification and optimisation. The report provides advice for deciding the radiation exposure situations that should be covered by the relevant regulations because their regulatory control can be justified, and, conversely, those that may be considered for exclusion from the regulations because their regulatory control is deemed to be unamenable and unjustified. It also provides advice on the situations resulting from regulated circumstances but which may be considered by regulators for exemption from complying with specific requirements because the application of these requirements is unwarranted and exemption is the optimum option. Thus, the report describes exclusion criteria for defining the scope of radiological protection regulations, exemption criteria for planned exposure situations, and the application of these concepts in emergency exposure situations and in existing exposure situations. The report also addresses specific exposure situations such as exposure to low-energy or low-intensity adventitious radiation, cosmic radiation, naturally occurring radioactive materials, radon, commodities, and low-level radioactive waste. The quantitative criteria in the report are intended only as generic suggestions to regulators for defining the regulatory scope, in the understanding that the definitive boundaries for establishing the situations that can be or need to be regulated will depend on national approaches.

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.

Radiation protection of people and the environment: developing a common approach.

The problem with the current ICRP system of radiation protection, particularly for regulators, is that it fails to differentiate between the application of justification and optimisation to people in the circumstances of medical care or as part of a workforce, compared with their application to members of the general public in an environmental setting; plus the fact that it also fails to address the issue of potential impacts on the rest of the environment in any meaningful way. But if these deficiencies are to be addressed, it will be essential to consider how protection of both people and the living environment can be achieved within a broad philosophical framework, using complementary approaches, based on the same underlying scientific knowledge. This paper briefly examines some of these issues, and offers some suggestions for developing a common, or even a combined, approach. It draws upon recent suggestions made by the ICRP itself with regard to radiological protection, plus current activities-on several fronts-to provide an explicit basis for environmental protection.

A system for protecting the environment from ionising radiation: selecting reference fauna and flora, and the possible dose models and environmental geometries that could be applied to them.

In order to demonstrate, explicitly, that the environment can be protected with respect to controlled sources of ionising radiation, it is essential to have a systematic framework within which dosimetry models for fauna and flora can be used. And because of the practical limitations on what could reasonably be modelled and the amount of information that could reasonably be obtained, it is also necessary to limit the application of such models to a 'set' of fauna and flora within a reference' context. This paper, therefore, outlines the factors that will need to be considered to select such 'reference' fauna and flora, and describes some of the factors and constraints necessary to develop the associated dosimetry models. It also describes some of the most basic environmental geometrics within which the dose models could be set in order to make comparisons amongst different radiation sources.

Strategic environmental management: time for a new approach.

Attempting to manage the environment as a whole, even from just a scientific standpoint, is not easy. The sheer size and scale can be daunting. It is difficult even to encompass the many facets involved. This short paper therefore attempts to tackle the problem by describing a framework approach which encompasses how one might assess the actual state of the environment at any one time; characterise the ever-changing pressures placed upon it; the manner by which the resultant problems need to be addressed; and thus what sort of responses are required. No system or framework is ever likely to be fully adequate, but some form of framework is essential in order to deliver a more sustainable approach to environmental management than has so far been achieved.

Estimating the quantities of persistent chemicals entering coastal waters of England and Wales from land-based sources.

Total load estimates of the inputs of Cd, Hg, Cu, Pb, Zn, lindane, total nitrogen, and orthophosphate into coastal waters of England and Wales are made annually. Some 320 inputs are currently routinely sampled and analysed. Results for the period 1990-1996 indicate that reductions have occurred in the inputs of all metals, and that such changes generally reflect actions taken to reduce industrial discharges, and thus the balance of point and diffuse sources. The pattern is however less clear for the other chemicals studied, where inputs are dominated by agricultural activities and changes in river flows.

A system for radiological protection of the environment: some initial thoughts and ideas.

Radiological protection has always been based on protection of man. Protection of the environment is often assumed to be implicit in the application of radiological protection generally, but this assumption is increasingly being challenged. It is therefore time to consider the feasibility of developing a complementary system for protecting the environment itself from ionising radiation, which would be both explicit and applicable to a wide range of situations. This paper outlines a possible approach using reference dose models and different types of dose effects.

The uptake by man of cadmium ingested in crab meat.

Seven male volunteers with normal iron stores ate the brown meat from crabs whose diet had contained radioactive cadmium-115m. Systemic uptake of cadmium by the volunteers, derived from measurements of their residual body radioactivity several weeks after intake, averaged 2.7 +/- 0.9 (se)%, essentially as found by others in studies with extrinsically labelled food.

Plutonium redistribution by biological activity in Irish Sea sediments.

As part of a programme investigating the fate of transuranium nuclides discharged to coastal waters we have studied the effects of benthic animals on plutonium redistribution in Irish Sea sediments. From analyses of burrow linings of the large echiuroid Maxmulleria lankesteri, which penetrates to depths exceeding 40 cm, we now show that this animal may have a significant effect on the removal of plutonium to deeper layers in the sea bed.

Occurrence and fate of organic and inorganic contaminants in marine animals.

Most chemical contaminants occur in highest concentrations in coastal waters, often maximized in very localized areas. In general, this situation represents the exposure pattern for marine animals. However, the availability of contaminant to an organism depends not only on its concentration but also on its chemical nature, its physical state, and whether the source of exposure is the surrounding seawater or the diet. Depending on the type of exposure, uptake occurs across absorptive surfaces, such as those of the respiratory apparatus or gastrointestinal tract, where selectivity may occur, even among neighboring homologs. Deposition in tissues, accumulation, degradation, or depuration depends on tissue type, metabolic processes, detoxification mechanisms, and the adaptive status of a particular animal. This hypothesis is examined briefly for hydrocarbons, pesticides, other miscellaneous organic contaminants, heavy metals, and radionuclides. It is concluded that most data relate to occurrence and distribution. Considerably less information is available on the underlying biochemical processes.