65
Chapter 5
Protection of the Environment
from the Effects of Radiation
ญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญญ
radiation and to demonstrate explicitly that the ecosys-
5.1. Introduction
tem and its components are not being harmed by expo-
There is a growing awareness that radiation risk man-
sure to radionuclides (Strand and Oughton, 2002).
agement needs to address the question of effects on the
The subject is specifically addressed within some
environment. Radiological protection has traditionally
agreements, for example the Joint Convention on the
been based on the protection of man. This is because the
Safety of Spent Fuel Management and on the Safety of
international advisory body on such matters, the Inter-
Radioactive Waste Management. Furthermore, the sec-
national Commission on Radiological Protection (ICRP),
ond principle of the International Atomic Energy Agency
has maintained a strong bias toward human health. The
(IAEA) Safety Fundamentals for the Management of Ra-
ICRP has stated that: `The Commission therefore be-
dioactive Waste states that: `Radioactive waste shall be
lieves that if man is adequately protected then other liv-
managed in such a way as to provide an acceptable level
ing things are also likely to be sufficiently protected'
of protection of the environment.' In addition, several
(ICRP, 1977). More recently, a caveat has been added
relevant agreements were made at the 1992 UNCED
(ICRP, 1991) stating that `individual members of non-
Earth Summit in which a number of general principles
human species might be harmed, but not to the extent of
for environmental protection were laid down. An exam-
endangering whole species or creating imbalance be-
ple is `The Rio Declaration' (UNCED, 1992) which em-
tween species'.
phasizes the issue of sustainable development in Princi-
The inadequacies of applying this approach to envi-
ple 4, by stating that `Environmental protection shall
ronmental protection are increasingly recognized, from
constitute an integral part of the development process
both scientific and ethical perspectives (Strand, 2002;
and cannot be considered in isolation from it.'
Strand et al., 2000). One problem is that no evidence is
given to support the ICRP statements, with the result
5.2. Frameworks for environmental protection
that regulatory bodies in many countries are not in a
position to demonstrate explicitly that the environment
Developing and defending a practical and coherent sys-
is being protected for a given situation. Laboratory stud-
tem of protection for flora and fauna raises a number of
ies and accidents have shown that radiation can have a
dilemmas and conflicts, including those relating to scien-
number of detrimental effects on biota, including mor-
tific, ethical, and legal issues. A better understanding of
tality, and reproductive and genetic damage. Neverthe-
ecological effects and their uncertainties primarily re-
less, current knowledge about the effects of radiation on
quires a framework for risk and impact assessment that
wild plants and animals is limited and subject to large
can incorporate the sensitivities of various species and
uncertainties, and there is little consensus on the rele-
ecosystems. Factors influencing sensitivity include expo-
vance and acceptability of these effects within the con-
sure pathways, uptake to biota, and dose-effect relation-
text of risk management. The ICRP statements are po-
ships. These can be ecosystem-dependent (for example,
tentially invalid in certain situations, for example when
nutrient status or biological activity) and species-depend-
pathways to man do not exist or are long and tenuous,
ent (such as high bioaccumulation of 99Tc by lobster or
or when accidents contaminate sparsely populated areas.
the radiosensitivity of pine compared to other tree spe-
Hence, there are likely to be situations where the resi-
cies). Acute lethal doses can vary by several orders of mag-
dent biota are exposed to harmful doses but doses to
nitude among and within species. Moreover, reproductive
man are maintained at levels well below the recom-
and population health effects may occur at much lower
mended dose limits (Pentreath, 1998). It could be antici-
doses than would kill an organism and there is little in-
pated that the Arctic, where human population densities
formation about the effects of low chronic exposure.
are very low and exposure pathways to humans can be
Ethical issues include whether animals have moral
relatively long, is a prime example.
status and why, the definition of harm in relation to the
For these reasons, there has been increasing pressure
exposed population or individuals, the balance between
to explicitly demonstrate environmental protection from
the interests of humans and non-human species, and the
radiation and to incorporate environmental considera-
fundamental issue of why the environment should be
tions into the system of radiological protection. AMAP
protected anyway. In common with many risk manage-
activities, focusing on radioactivity and other hazardous
ment policies, the answers will need to reflect both sci-
substances, have played an important role in driving the
entific knowledge and ethical values. Interestingly, many
debate, particularly by highlighting inconsistencies be-
of the groups concerned with the protection of the envi-
tween the approaches taken for radioactivity and other
ronment from radiation, including the IAEA and ICRP,
environmental pollutants (Strand et al., 2002). Wide-
have identified a need to address the ethical and philo-
spread international consensus has been reached over
sophical questions. AMAP has collaborated on work
the last couple of years on the need to develop a ration-
with the International Union of Radioecologists (IUR),
ale for the protection of the environment from ionizing
which was one of the first international organizations to

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66
AMAP Assessment 2002: Radioactivity in the Arctic
actively promote the need to focus on non-human biota
1. It is the responsibility of all humankind, where possi-
and to propose a system for impact assessment.
ble, to prevent detriment to the environment and to pre-
Any framework for the protection of the environ-
serve and protect the health and integrity of the Earth's
ment from radiation should be compatible with protec-
ecosystem. (Principle of responsibility).
tion systems for other environmental stressors. How-
2. The use and exploitation of natural resources must
ever, it is important to be aware that this area of law is
be sustainable and should equitably meet the develop-
under continuing development. There is general world-
mental and environmental needs of present and future
wide consensus on the issue of human rights (although
generations. (Principle of sustainable development).
not total agreement on how those principles might be
applied in practice), which simplifies the management of
3. Society must recognize the serious impact of humans
human radiation exposure in some respects. Nothing
in causing extinction and a loss in species and actively
like the same level of agreement has been reached on en-
promote conservation measures to preserve the Earth's
vironmental principles however, although progress is
biodiversity. (Conservation/biodiversity principle).
being made and is pertinent to the present assessment.
4. Humans should avoid causing suffering to other liv-
There are three major points to bear in mind when ad-
ing organisms. (Welfare principle).
dressing the development of frameworks for protection
5. Humans should respect the inherent and intrinsic
of the environment from radiation. First, legislation for
worth of nature, recognizing that the environment has a
environmental protection is relatively new and still un-
value beyond its direct impact on human interest. (Prin-
dergoing development. Second, the issue is global, is
ciple of respect).
deemed important by governments and the public alike,
and has stimulated action on an international scale.
6. Environmental management needs to be combined
Third, practical solutions are not without conflict and
with concerns for economic and social justice (particu-
controversy. Not withstanding these difficulties, exam-
larly in developing countries) and with the informed
ples of environmental law can be found in the national
participation of affected citizens. (Principle of environ-
laws of every country. Although their scope and detail
mental justice).
vary considerably, progress during the last 30 years has
7. Decisions on environmental issues should reflect sci-
led to a certain amount of agreement on what is meant
entific understanding, acknowledge uncertainties, and rec-
by the `environment' and its `protection' and which
ognize the identity, role, culture, and specific knowledge
principles should guide that protection (see Box 5ท1).
of indigenous peoples, traditional practices, and local
communities. (Transparency and participation principle).
5.2.1. General legal and ethical principles
8. In order to protect the environment, a precautionary
approach should be encouraged. Where there are threats
A two-stage approach is useful when assessing the legal
of serious or irreversible damage, lack of full scientific
and ethical basis for the development of a framework
certainty should not be used as a reason for postponing
for environmental protection, namely: to consider some
cost-effective measures to prevent environmental degra-
general and/or common legal and ethical principles used
dation. (Precautionary principle).
in environmental protection; and then to derive some
policy or management principles on the basis of these
9. Authorities should promote the internalization of en-
being specifically relevant and pertinent to protection
vironmental costs taking into account that the polluter
from radiation.
should bear the costs of pollution, including those con-
The following principles are drawn from interna-
nected to liability and compensation. (Polluter pays
tional and national environmental policy (i.e., the Rio
principle).
Declaration; and policy arising from the European
10. The need to prevent environmental damage at
Union, the U.S. Environmental Protection Agency, and
source requires that environmental impact assessments
the U.K. Environment Agency) or from environmental
should be carried out for all new developments, propos-
ethics. The list is not exclusive and reflects the broad is-
als, and technologies. (Environmental impact; justifica-
sues and spirit of international and national law.
tion principle).
Box 5ท1. Definitions
The term environment has been defined in a number of national and international laws. Common to most definitions is the notion
that the environment consists of man, biota (e.g., microorganisms, plants, and animals), abiota (e.g., soil, water, and air), physical
surroundings (e.g., climate, and light), and their interactions. Some definitions extend to both natural and man-made features of
the environment (i.e., cultural heritage, and buildings); some limit the definition to those external factors having a direct effect on
living organisms.
Protection of the environment is predominantly perceived as the prevention of detriment to the environment and its living com-
ponents. But the term can also encompass restoration, enhancement, and maintenance of environmental quality. While recogniz-
ing natural environmental stressors, most legislation and international conventions deal specifically with anthropogenic effects.
In the broadest sense protection of the environment from ionizing radiation might include all biotic and abiotic components of the
Earth's biosphere. In a more practical sense, the abiotic component of the biosphere is known to be unaffected directly by the ef-
fects of radiation under all but the most extreme of conditions. In some instances, an interpretation of `damage' might reflect that
an environment is contaminated per se, particularly for ecosystems perceived as `pristine' such as the Arctic. However, in most
cases, efforts to quantify systematically the consequences of radiation exposure and to develop a system for protection might be
more constructively focused on the most sensitive components of the biosphere, i.e., living organisms, but not totally excluding the
abiotic environment.
At present, the only part of the environment explicitly considered for protection from ionizing radiation is man.

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Chapter 5 ท Protection of the Environment from the Effects of Radiation
67
Depending on the context, some principles may be
calculation of doses to organisms with varying geome-
deemed more relevant than others and some more fun-
tries (e.g., consensus is required in adapting these al-
damental than others. In practice, the principles may even
gorithms for use within a protection framework); and
conflict (e.g., 5 and 6). Principles 1 to 5 concern the ques-
ท a set of doseญeffect relationships for reference organ-
tion of why it is necessary to protect the environment,
isms that could include data from low-exposure (e.g.,
and 6 to 10 how to achieve this protection in practice.
cytogenetic effects) to high-exposure (e.g., lethal ef-
The IAEA recently concluded that despite the appar-
fects) situations.
ent diversity of values in the different ethical outlooks,
Discussion within the scientific community has led to
consensus on principles of environmental protection was
the adoption of these points into a proposed strategy
sufficient to identify five common principles, namely:
comprising three key components (IUR, 2000), namely:
conservation of habitat and species; maintenance of bio-
exposure pathways and retention of radionuclides by
diversity; sustainability; environmental justice; and hu-
biota; dose calculations; and dose-effect relationships.
man dignity (IAEA, 2002). Clear support for these five
principles was obtained at the IUR consensus conference
in 2001, which was attended by participants represent-
5.2.3.1. Exposure pathways
ing a wide range of disciplines connected to radiation
and retention of radionuclides by biota
protection and environmental protection. Participants
The outcome of the work on exposure pathways will be
identified a need for `development of policy in an open,
based on the acquisition and synthesis of information
transparent, and participatory manner', considered that
concerning ecological characteristics and radionuclide
`the best available technology, including consideration
uptake within selected ecosystems. Simple reference mod-
of economic costs and environmental benefits, should be
els could be developed for the simulation of radionuclide
applied to control any release of radionuclides into the
migration and uptake to the whole organism (and or-
environment', and supported a precautionary approach
gans if applicable) for those reference species living in
to risk management (Strand and Oughton, 2002).
representative terrestrial and aquatic ecosystems.
5.2.2. Management of environmental risk
5.2.3.2. Dose calculations
In general, programs addressing the management of en-
Radiation dosimetry models will be developed for the ref-
vironmental risk can be grouped (although somewhat
erence organisms. These will be designed to estimate the
arbitrarily) into three categories:
actual or potential absorbed dose rates to the organisms
ท management through pathway-based analysis of ex-
from internal and external sources of -, -, and -radia-
posure, often involving environmental standards (e.g.,
tion. The final output will be a tabulation of absorbed
radiation dose to certain organisms or concentrations
dose rate coefficients (Gy/hr per unit radionuclide activity
of radionuclides in environmental media);
concentration in the relevant environmental compart-
ท management through process standards relevant to
ment) for each reference organism for the radionuclides of
specific source(s) based on best available technology
concern. It is likely that the reproductive organs will be
(BAT) and similar criteria of technical status and per-
important targets for inclusion in the dosimetry models.
formance; and
ท pure management standards, which may include certi-
fication schemes or schemes that ensure that positive ac-
5.2.3.3. Doseญeffect relationships
tion is taken to protect the environment and where conti-
Endpoints of concern in individual generic organisms
nuous performance improvement is sought. An example
could be defined and dose rate/response relationships for
is the EC Eco-Management and Audit Scheme (EMAS).
the chosen endpoints tabulated. This would involve the in-
Pathway-based schemes are generally considered most
tegration of data from earlier reviews, and assessments of
relevant to the development of assessment frameworks
the potential impacts of radiation in the environment, as-
for the environment, but aspects of other schemes may
sessments of the wider radiobiological literature, and as-
be incorporated when appropriate.
sessments of newly available information from the Kysh-
tym (see Section 7.5.1) and Chernobyl accidents. Relevant
effects of radiation will probably include, but not neces-
5.2.3. System for environmental impact assessment
sarily be limited to, changes in morbidity, mortality, fer-
A coherent and logical environmental impact assessment
tility, fecundity, and mutation rate. Information will be
methodology for ionizing radiation is essential (Pen-
organized so as to indicate the approximate dose rate/re-
treath, 1999). Components that could form the basis for
sponse relationships. An attempt should be made to quan-
such a system include:
tify the intrinsic uncertainty in these threshold dose rates
(e.g., through the extrapolation of laboratory data to nat-
ท a set of reference organisms ญ not all organisms can be
ural conditions) and to indicate possible modifying influen-
studied, necessitating a selection procedure;
ces (e.g., the influence of other environmental variables).
ท a set of quantities and units to express doses to biota.
Currently, doses are expressed in Grays per unit time,
which does not reflect the variable biological effects
5.2.4. Target level of biological hierarchy
arising from equal absorbed doses of differing radia-
tion types;
It is generally recognized that protective action should
ท a defined set of dose models for a number of reference
be taken in such a way as to ensure that populations of
flora and fauna. Methodologies exist which allow the
organisms receive an adequate level of protection (IAEA,

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68
AMAP Assessment 2002: Radioactivity in the Arctic
1992, 2000) and that the functioning of their associated
5.2.6. Practical and ethical advantages
ecosystems is unaffected by the presence of a contami-
of the framework
nant. A practical approach to ensure that unacceptable
effects on populations are avoided is to target protective
A number of practical and ethically-relevant advantages
action at the organizational level below populations, i.e.,
of this framework can be highlighted; the framework
individuals. This is justified on the basis of a number of
is site- and case-specific, transparent, involves stake-
precepts, including:
holder participation, enables comparison with other
environmental contaminants, is `bottom-up'; is applic-
ท population effects are unlikely to be manifested if indi-
able to individuals and populations; and is compatible
viduals are unaffected;
with anthropocentric and ecocentric environmental phil-
ท population effects are more complex to assess than ef-
osophies.
fects on individuals and more likely to be masked by
the normal range of spatial and temporal ecosystem
variability;
5.2.6.1. Site- and case-specific
ท scientific information on population effects is compar-
That the framework is site- and case-specific promotes
atively scarce; and
the notion that there may be a number of different rea-
ท in protecting threatened or endangered species, con-
sons for protecting the environment. For example, the
sideration of individuals is necessary.
case may depend on available alternatives, the ecosystem
However, the reasoning is not straightforward in all
itself (e.g., a protected habitat or common resource),
cases, bearing in mind that:
and/or the organisms it contains (e.g., endangered spe-
cies). There is also uncertainty in going from a measure-
ท for a variety of species (e.g., with asexual or vegetative
ment of concentrations in abiotic compartments (e.g.,
propagation), individuals and populations in the con-
soil, water), to calculations of accumulation and doses
ventional sense may be difficult to differentiate;
in organisms, and to estimates of cellular up to ecosys-
ท there are cases where individuals may be affected (e.g.,
tem effects. Source-specific, site-specific, species-specific,
in the case of endocrine disrupters) while populations
and individual-specific variability all contribute to such
remain unaffected; and
uncertainty. This complexity has the disadvantage of in-
ท in the case of stochastic effects, effects may be observed
troducing difficulties and there may be cases where a
in individuals while not affecting the viability of the
simple approach is sufficient. Until better scientific evi-
population.
dence is available to support such judgments, oversim-
plification should be avoided.
5.2.5. Dose or dose rate as an indicator
of actual or potential impact
5.2.6.2. Transparency
One approach to environmental assessment involves the
The framework is transparent in that it indicates the po-
calculation of the dose or dose rate to reference organ-
tential consequences of actions and how these were de-
isms. The rationale being that biological effects of radia-
rived. It also provides information relevant to the issue
tion are mediated through the absorbed dose and much
of `risk', for example, uncertainties as to outcome, prob-
information is available linking the severity of effects to
abilities of harmful effect, errors in dose-risk calcula-
the dose or dose rate.
tions, and model sensitivity. Honesty about the level of
Alternatively, assessments could be based on ra-
scientific knowledge (meaning some distinction between
dionuclide activity concentrations. However, the dose is
what is widely acknowledged as fact, generally accepted,
further modified by the type of radionuclide and exter-
disputed, difficult to predict, unknown, etc.) is funda-
nal and internal geometry, as well as other factors such
mental to building public trust; short-sightedness or dis-
as lifespan and size. Activity concentrations could be of
honesty is one of the fastest ways to lose this trust.
relevance in compliance discussions, e.g., by comparing
expected/observed concentration data with data from
5.2.6.3. Stakeholder participation
dose standards (e.g., U.S. DOE, 2002). However, for as-
sessing effects, including the radiation dose or dose rate
The framework promotes a more open debate on the
adds transparency.
acceptability of the consequences of radiation exposure
Several dosimetry models are available for aquatic
to biota, and encourages public and stakeholder par-
and terrestrial environments, although these are not
ticipation in such debates. A simple statement that `re-
necessarily sufficiently comprehensive for developing a
leases are below dose limits' tends to beg the question as
framework for environmental protection. For the aquatic
to where the limits came from and whether they are ap-
environment, the generic models relate to: small and
propriate. It is also questionable whether the public is
large phytoplankton; pelagic and benthic crustaceans;
sufficiently competent to participate in such debates,
benthic molluscs; and pelagic and benthic fish. These
and whether the perceptions influencing attitudes to their
have been developed to the point at which dose rate fac-
own risk ญ for example, whether voluntary or imposed ญ
tors have been tabulated for a range of radionuclides in
are equally relevant to the question of what is acceptable
environmental media (Amiro, 1997; Pentreath and Wood-
to animals and other living organisms. The public is not
head, 1988). It is envisaged that future work will focus
always `rational' and consistent in the way it values
on the development of the dosimetry models, and the as-
animals (dogs and pandas being more important than
sociated dose conversion factors that relate directly to
mosquitoes and worms). Who decides which factors are
the reference organisms (and their local environment).
relevant?

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Chapter 5 ท Protection of the Environment from the Effects of Radiation
69
of Environmental Impact) and EPIC (Environmental
5.2.6.4. Comparison with other
Protection from Ionising Contaminants in the Arctic).
environmental contaminants
There is a need for the development of a framework
Because the framework provides information on effects
for the protection of the environment from ionizing ra-
and uncertainties for a range of endpoints, it should be
diation. This is also required to structure the informa-
possible to use that information to compare the environ-
tion derived from earlier studies in order to direct future
mental effects of other practices or alternative actions.
scientific research. Such a system will include environ-
Effects from radiation exposure may be compared di-
mental transfer models, environmental dosimetry mod-
rectly with effects of other environmental stressors,
els, and tabulated dose-effect relationships. The system
many of which result in the same biological endpoints.
will also require `reference organisms' (i.e., a group of
This is an important step towards `holistic' environmen-
organisms that are selected from a number of criteria
tal management, and promotes coherence with other
such as radiosensitivity, accumulation potential, ubiq-
methods.
uity, and importance to ecosystem functioning) and the
derivation of relevant quantities and units. The final sys-
tem should allow regulators to explicitly and transpar-
5.2.6.5. Bottom-up
ently demonstrate a commitment to environmental pro-
In ecotoxicology, there is often talk of a distinction be-
tection and should provide a basis for developing stan-
tween `bottom-up' and `top-down' systems. This para-
dards against which to test for compliance of current
digm has attracted increasing attention, largely owing to
and future practices.
scientific developments in the analytical techniques used
to study the mechanisms and processes of environmental
5.3. Arctic-specific issues
effect (e.g., molecular biology, population studies, and
vulnerable species). A `bottom-up' system means that
The Arctic requires special attention in the selection
the framework first acknowledges that actions can have
of reference organisms owing to its greater vulnerability
a variety of effects on the environment (from DNA to
and lesser abundance of species. The project EPIC ญ an
ecosystems), and considers a range of biological end-
EC Inco-Copernicus funded research project coordi-
points, changes, and causes. From a risk management
nated by the Norwegian Radiation Protection Author-
point of view, the question is: What might we do and
ity ญ aims to develop a methodology for the protection
how can we avoid doing it? A `top-down' system focuses
of natural populations of organisms in Arctic ecosys-
on constraints, standards, and compliance, usually de-
tems from radiation. One component has been the de-
rived from `no observed effect level' or `critical load' cri-
velopment of a list of Arctic-specific reference organ-
teria. In this case, the question is: How much can we do?
isms (Beresford et al., 2001). These were proposed on
the basis of their ecological niche, radiosensitivity,
likely internal and/or external exposure to radionu-
5.2.6.6. Applicable to individuals and populations
clides, and their suitability for monitoring and/or fu-
The main area of focus for the framework is individual
ture research.
organisms. This is sometimes necessary from the point of
protection, as in the case of protected species. But evalu-
5.3.1. Identification of reference organisms
ation of possible population effects can also be derived
5.3.1.1. Biological endpoints
from individual effects. Also, the individual is often the
highest level at which scientific experiment and hypoth-
The four `umbrella' types of biological effect are mor-
esis testing can be directed. Observed biological or phys-
bidity (the general well-being of the organism), mortal-
iological effects on an individual organism (or its cells,
ity, reproductive success, and cytogenetic effects.
DNA, etc.) may be reduced causally to the radiation ex-
The choice of endpoints will be facilitated by the de-
posure; subsequent effects at a population or ecosystem
velopment of a database for biological effects on a num-
level require more complicated ecological modelling.
ber of groups of terrestrial and aquatic fauna and flora.
The effects of radiation on plants and animals have been
reviewed many times from the perspective of assessing
5.2.6.7. Compatible with anthropocentric
the potential impacts of radioactive waste disposal (IAEA,
and ecocentric environmental philosophies
1976, 1988, 1992; NCRP, 1991; UNSCEAR, 1996).
Lastly, the framework is compatible with anthropocen-
The present need is to structure this information so as to
tric and non-anthropocentric (i.e., ecocentric) environ-
identify the levels of dose rate at which different degrees
mental philosophies and can be incorporated into na-
of damage might be produced in the endpoints of inter-
tional environmental legislation.
est. This will also identify gaps in scientific knowledge
that could lead to further research to improve the level
of understanding of these topics.
5.2.7. Conclusions
A system for assessing the consequence of radiation ex-
5.3.1.2. Identification based on exposure
posure on Arctic flora and fauna should have high prior-
ity. This requires collaboration at the international level
For a suite of radionuclides, expert judgment and trans-
and, with this in mind, joint activities are planned be-
fer models can be applied in order to identify which or-
tween AMAP and IUR. The European Commission has
ganisms assimilate and retain radionuclides to a high de-
also initiated further scientific developments through the
gree and which organisms occupy habitats that are likely
research projects FASSET (Framework for Assessment
to concentrate enhanced levels of radioactivity.

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70
AMAP Assessment 2002: Radioactivity in the Arctic
and sensitivities for different groups overlap consider-
Viruses
ably. These criteria indicate that mammals and birds
Mollusks
should be included in any suite of reference organisms.
Protozoa
Bacteria
5.3.1.5. Distribution and practicality
Moss, lichen, algae
for research and monitoring
Insects
There is little point selecting reference organisms that
Crustaceans
are not widely distributed through at least one of the
Reptiles
three Arctic zones (High-, Low-, and subarctic). Species
Amphibians
known to occur in these zones, for those groups for
Fish
which there is sufficient information, are listed in the
Higher plants
EPIC report (Beresford et al., 2001). The practicality of
collecting the organisms for monitoring purposes (to de-
Birds
termine the radionuclide content or to assess effects due
Mammals
to exposure) or to enable further radiosensitivity and
1
10
100
1000
10 000
radioecological studies is a further consideration. For
Acute lethal dose, Gy
some groups, this would be difficult owing to their pro-
Figure 5ท1. Comparative radiosensitivity of different organisms rep-
tected status (e.g., raptors, marine mammals) or their
resented by the acute lethal dose ranges (UNSCEAR, 1996).
perceived public sentiment (e.g., marine mammals, large
terrestrial carnivores). Also, some potential reference or-
The habits and habitat of different life stages of some
ganisms are of commercial importance, for example,
organisms may vary considerably (e.g., bird and egg, lar-
macroalgae (in the Norwegian, Barents, and White Seas),
val and adult insects) and this may lead to different ex-
benthic fish (haddock, Greenland halibut, European
posure pathways. This should be considered when se-
plaice) and pelagic carnivorous fish (Atlantic cod). Tak-
lecting reference organisms. A selection of candidate ref-
ing these factors into account, a selection of appropriate
erence organisms for European ecosystems based purely
organism groups are listed in Table 5ท1.
on radioecological criteria were drawn up by Strand et
al. (2001).
5.3.1.6. Examples of reference organisms
A search for candidate reference organisms occurred
5.3.1.3. Identification based on ecological relevance
during the EPIC project. In this respect, it must be em-
Ecological sensitivity is defined in terms of the role of
phasized that the term `reference organism' does not
the organism in the ecosystem concerned. A number of
imply a particular species, but serves as a surrogate.
factors are relevant, e.g., population size; trophic level;
Thus, in principle, it should be possible to identify spe-
reproductive strategy, including generation time; size;
cific plants and animals that are listed under the heading
habitat; seasonal variations; physiological features; and
`reference organism' (Table 5.1). In the practical applica-
biological complexity.
tion of the system, `secondary reference organisms' may
The simple approach, as used in EPIC, is to assess the
need to be defined at the species level. For example, in
requirements for representation of each trophic level.
the case of a carnivorous terrestrial mammal, the Arctic
Dominant organisms at each trophic level are responsi-
fox (Alopex lagopus) might be selected and in the case of
ble for the major energy and nutrient flows in the eco-
a marine benthos-eating bird, the common eider (Soma-
systems; therefore, it could be argued that protection of
teria mollissima). The selection process is driven by fac-
these organisms (by their selection as reference organ-
tors such as ubiquity and practicability for monitoring.
isms) will ensure the protection of the ecosystem as a
whole.
Table 5ท1. Groups from which aquatic and terrestrial reference or-
ganisms should be selected (Beresford et al., 2001).
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5.3.1.4. Identification based on radiosensitivity
Aquatic
Terrestrial
reference organisms
reference organisms
The effects of ionizing radiation on living organisms
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have been reviewed extensively (Rose, 1992; UN-
Benthic bacteria
Lichens and bryophytes
Macroalgae (marine)
Gymnosperms
SCEAR, 1996). The comparative sensitivity of different
Aquatic plants (freshwater)
Monocotyledons
organisms to radiation in terms of acute lethal dose is
Phytoplankton
Dicotyledons
shown in Figure 5ท1. Although other radiation-induced
Zooplankton
Soil microorganisms
effects (e.g., morbidity, fertility, and fecundity) may also
Molluscs
Soil invertebrates
be important; as a thorough review of these `other' fac-
Polychaetes (marine)
Herbivorous mammals
Insect larvae (freshwater ญ benthos)
Carnivorous mammals
tors has not yet been conducted the comparative lethal
Pelagic fish (planktotrophic)
Bird eggs
dose (mortality) was used to aid the selection of refer-
Pelagic fish (carnivorous)
ence organisms.
Benthic fish
Available data on acute lethal dose exposures indi-
Carnivorous mammals
cate that mammals and birds are the most radiosensitive
Benthos-eating birds
Fish eggs
groups, although the radiosensitivity ranges are large
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