MEMORANDUM

THE EVOLUTION OF THE SYSTEM OF RADIOLOGICAL PROTECTION:
THE JUSTIFICATION FOR NEW ICRP RECOMMENDATIONSThe International Commission on Radiological Protection∗
ABSTRACTICRP has been encouraging discussion, during the past few years, on the best way of
expressing radiological protection philosophy in its next Recommendations, which it plansto publish in 2005. The present recommendations were initiated by Publication 60 in1990 and have been complemented by additional publications over the last twelve years.
It is now clear that there is a need for the Commission to summarise the totality of thenumber of numerical values that it has recommended in some ten reports. This has been
done in this paper and from these, a way forward is indicated to produce a simplified andmore coherent statement of protection philosophy for the start of the 21st century. A
radical revision is not envisaged, rather a coherent statement of current policy and asimplification in its application.
INTRODUCTION
1. The 1990 system of protection, set out in Publication 60, was developed over some
30 years. During this period, the system became increasingly complex as theCommission sought to reflect the many situations to which the system applied. This
complexity involved the justification of a practice, the optimization of protection,
including the use of dose constraints, and the use of individual dose limits. It has
also been necessary to deal separately with endeavours prospectively involving
radiation exposure, ‘practices’, for which unrestricted planning was feasible for
reducing the expected increase in doses, and existing situations for which the only
feasible protection action was some kind of ‘intervention’ to reduce the doses. The
Commission also considered it necessary to apply the recommendations in different
ways to occupational, medical, and public exposures. This complexity is logical, but it
has not always been easy to explain the variations between different applications.
2. The Commission now strives to make its system more coherent and comprehensible,
while recognising the need for stability in international and national regulations,many of which have relatively recently implemented the 1990 Recommendations.
However, new scientific data have been produced since 1990 and there aredevelopments in societal expectations, both of which will inevitably lead to somechanges in the formulation of the Recommendations.
3. The previous 1977 Recommendations were made in Publication 26, which establishedthe three principles of the system of dose limitation as Justification, Optimization and
Limitation. Assessments of the effectiveness of protection can be related to thesource that gives rise to the individual doses (source-related) or related to theindividual dose received by a person from all the sources under control (individualrelated). Optimization of protection is a source-related procedure, while theindividual-related dose limits provide the required degree of protection from all thecontrolled sources.

∗

Presented by Professor Roger Clarke, ICRP Chairman. E-mail roger.clarke@nrpb.org

1

4. Optimization of protection was to be applied to a source in order to determine that
doses are ‘as low as reasonably achievable, social and economical considerations
being taken into account’, and decision-aiding techniques were proposed. In
particular, the Commission recommended cost-benefit analysis as a procedure toaddress the question, ‘How much does it cost and how many lives are saved?’ The
Commission recommended that the quantity Collective Dose should be used inapplying those optimization techniques to take account of the radiation detrimentattributable to the source in question. This quantity was unable to take account of
the distribution of the individual doses attributable to the source. Attempts weremade to address this problem in Publications 37 and 55, by suggesting a costing ofunit collective dose that increased with individual dose received, the procedure was
essentially never adopted internationally.
5. The issue was partially resolved in the 1990 Recommendations: while it was still
stated, as in 1977, that in relation to any particular source within a practice, thedoses should be as low as reasonably achievable, social and economic factors being
taken into account, it then continued:‘This procedure should be constrained by restrictions on the doses to individuals(dose constraints), or the risks to individuals in the case of potential exposures(risk constraints), so as to limit the inequity likely to result from the inherent
economic and social judgements’ (Paragraph 112).
The concept of the constraint has not been clearly explained by the Main Commissionin its subsequent publications. It has not been understood and, although it has been
the subject of debate by international bodies, it has not been sufficiently utilised nor
has it been implemented widely. The Commission now aims to clarify the meaning
and use of the constraint.
6. The dose constraint was introduced because of the need to restrict the inequity of
any collective process for offsetting costs and benefits when this balancing is not thesame for all the individuals affected by a source. Before 1990, the dose limit
provided this restriction, but in Publication 60 the definition of a dose limit waschanged to mean the boundary above which the consequential risk would be deemedunacceptable. This was then considered to be inadequate as the restriction on
optimization of protection and lower value constraints were required to achieve this.
7. This introduction of the constraint recognised the importance of restricting the
optimization process with a requirement to provide a basic minimum standard ofprotection for the individual.
8. The principles for intervention set out in Publication 60 are expressed in terms of alevel of dose or exposure where intervention is almost certainty warranted (i.e.,justified), which is followed by a requirement to maximise the benefit of theintervention (i.e., the protection level should be optimized). This is effectively an
optimization process and therefore it may be seen in exactly the same terms as forpractices, i.e. there is a restriction on the maximum individual dose and then theapplication of the optimization process that is itself expected to lead to lower doses
to individuals.
9. It can be seen then that all of the Commission Recommendations since 1990, bothfor practices and for interventions, have been made in terms of an initial restriction
on the maximum individual dose in the situation being considered, followed by a2

requirement to optimize protection. This underlines the shift in emphasis to include
the recognition of the need for individual protection from a source.
10. The new recommendations should be seen, therefore, as extending therecommendations in Publication 60 and those published subsequently, to give asingle unified set that can be simply and coherently expressed. The opportunity isalso being taken to include a coherent philosophy for natural radiation exposures andto introduce a clear policy for radiological protection of the environment.
THE PRESENT SITUATION
11. Since the 1990 recommendations there have been nine publications, listed in Table 1,that have provided additional recommendations for what are effectively to be
regarded as ‘constraints’ in the control of exposures from radiation sources. When
ICRP 60 is included, there exist nearly 30 different numerical values for ‘Constraints’,
which are set out in Table 2, in the ten reports that define current ICRP
recommendations. Further, the numerical values are justified in some six different
ways, which include,
a.
b.
c.
d.
e.
f.

Individual annual fatal risk,
Upper end of an existing range of naturally occurring values,
Multiples or fractions of natural background,Formal cost-benefit analysis,
Qualitative, non-quantitative, reasons, andAvoidance of deterministic effects

The rationale for the constraints in Table 2 is indicated using these letters a-f.

Table 1. ICRP RECOMMENDATIONS MADE SINCE PUBLICATION 60.
Publication 62

Radiological Protection in Biomedical Research

Publication 63

Publication 65

Principles for intervention for Protection of the Public in a
Radiological Emergency
Protection from Potential Exposure: A Conceptual
Framework
Protection against Radon-222 at Home and at Work

Publication 75

General Principles for Radiation Protection of Workers

Publication 76

Protection from Potential Exposures: Application to
Selected Radiation Sources
Radiological Protection Policy for the disposal ofRadioactive Waste
Radiation protection Recommendations as Applied to the
Disposal of Long-lived Solid Radioactive Waste
Protection of the Public in Situations of Prolonged
Radiation Exposure

Publication 64

Publication 77
Publication 81
Publication 82

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TABLE 2. COMPILATION OF THE EXISTING ICRP ‘CONSTRAINTS’ TO
OPTIMIZATIONSITUATION TO WHICH IT APPLIES
Effective Dose*

Basis+

Publication
NORMAL OPERATION OF A PRACTICE~0.01 mSv/a
0.1 mSv/a
0.3 mSv/a
20 mSv/a
10 mSv/a(1500 Bq m-3)
2 mSv
1 mSv
1 mSv/a

a, c
e
e
a
b
e
a, c
a, c

Exemption level, protection optimized
Constraint for long-lived nuclides
Maximum public constraint
Maximum worker constraint
Worker Constraint for Rn-222-Optimized level between 500-1500 Bq m-3
Surface of the abdomen of pregnant worker
Foetal dose over remaining term of pregnancy
Dose limit for the public

64, 7682
77
60, 6865
60
75
60

PROLONGED EXPOSURE∼10 mSv/ac∼100 mSv/a
10 mSv/a(600 Bq m-3)
∼1 mSv/ac, fb

10-5 /aac

Below this intervention is optional, but not likely
to be justifiable
Intervention almost always warranted
Constraint for Rn-222 at home
-Optimized level 200-600 Bq m-3
Intervention
Exemption
Level,
protection
optimized
Risk constraint

82
82
65
82
81

BIOMEDIAL RESEARCH
0.1 mSv
1.0 mSv
10.0 mSv> 10.0 mSv

a
a
a
a

Minor level of societal benefit
Intermediate level of societal benefit
Moderate level of societal benefit
Substantial level of societal benefit

62
62
62
62

SINGLE EVENTS AND ACCIDENTS
Effective Dose*
Averted
50 mSv
500 mSv
5000 mSv skin5000 Gy thyroid
1000 mSv
1000 mSv
5000 mSv skin
10 mSv
100 Bq/g (α),
10000 Bq/g (β/γ)

e, c
e, c

Sheltering warranted – optimized 5-50 mSv
Evacuation warranted– optimized 50-500 mSv

63
63

e, c
d, a
f

Issue stable iodine – optimized 50-500 mSv
Arrange relocation (-10s mSv per month)
Constraint for planned emergency work

63
63, 8263c, dOptimized value for foodstuffs 10-100 Bq/g (α),
1000-10000 Bq/g (β/γ)

63*Unless otherwise stateda. individual annual fatal risk, b. upper end of an existing range of naturally occurring
values, c. multiples or fractions of natural background, d. formal cost-benefit analysis, e.
qualitative, non-quantitative, reasons, and f. avoidance of deterministic effects+412. The Commission had previously suggested the term ‘Protective Action Level’ (PAL) be
used in the specification of the restriction of individual doses from single sources. The
term appeared to cause concern and was not well understood. The Commission has
considered the issue and now feels that the already established term ‘constraint’
correctly reflects the concept it wishes to promote.
13. The question to be addressed is whether, for the future, fewer constraints may berecommended that are sufficient to encompass the needs of radiological protection,
and whether they can be established on a more uniform and consistent basis.
MAJOR CHANGES FROM THE 1990 RECOMMENDATIONS
14. The primary aim of the Commission continues to be contributing to the establishment
and application of an appropriate standard of protection for human beings and now
explicitly for other species. This is to be achieved without unduly limiting thosedesirable human actions and lifestyles that give rise to, or increase, radiation
exposures.
15. This aim cannot be achieved solely on the basis of scientific data, such as thoseconcerning health risks, but must include consideration of the social sciences. Ethicaland economic aspects have also to be considered. All those concerned withradiological protection have to make value judgements about the relative importanceof different kinds of risk and about the balancing of risks and benefits. In this, they
are no different from those working in other fields concerned with the control ofhazards. The restated recommendations will need to recognise this explicitly.
16. Where exposures can be avoided, or controlled by human action, there is arequirement to provide an appropriate minimum, or basic, standard of protection
both for the exposed individuals and for society as a whole. There is a further duty,
even from small radiation exposures with small risk, to take steps to provide higher
levels of protection when these steps are effective and reasonably practicable. Thus,
while the primary emphasis is now on protection of individuals from single sources, itis then followed by the requirement to optimize protection to achieve the best levelof protection available under the prevailing circumstances.
17. In order to achieve this, it is proposed that the existing concept of a constraint be
extended to embrace a range of situations to give the levels that bound the
optimization process for a single source. The optimization of protection from thesource may involve either, or both, the design of the source or modification of thepathways leading from the source to the doses in individuals. They would replace a
range of terms that include intervention levels and action levels since there would be
no need to distinguish intervention situations separately, constraints, clearance levels
and exemption levels as well as the dose limits for workers and the public.
18. There will be a revision to the radiation and tissue weighting factors in the definitionof Effective dose. A coherent philosophy for natural radiation exposures will be
included and a clear policy for radiological protection of the environment will be
introduced.
THE 2005 SYSTEM OF PROTECTION
19. The Commission now recognises that there is a distribution of responsibilities for
introducing a new source leading to exposures, which lies primarily with society atlarge, but is enforced by the appropriate authorities. This requires application of the5principle of JUSTIFICATION, so as to ensure an overall net benefit from the source.
Decisions are made for reasons that are based on economic, strategic, medical, anddefence, as well as scientific, considerations. Radiological protection input, while
present, is not always the determining feature of the decision and in some cases
plays only a minor role. The Commission now intends to apply the system ofprotection to practices only when they have been declared justified, and to natural
sources that are controllable.
20. The justification of patient diagnostic exposures is included, but has to be treatedseparately in the recommendations, because it involves two stages of decisionmaking. Firstly, the generic procedure must be justified for use in medicine and,secondly, the referring physician must justify the exposure of the individual patient interms of the benefit to that patient. It is then followed by a requirement to optimize
patient protection and the Commission has advocated the specification of Diagnostic
Reference Levels as indicators of good practice (See paras. 48-53).
21. The system of protection being developed by the Commission is based upon thefollowing principles, which are to be seen as a natural evolution of, and as a further
clarification of, the principles set out in Publication 60. Once the source is justified bythose appropriate authorities, the radiological principles may be expressed as,
For each source, basic standards of protection are applied for the most exposed
individuals, which also protect society- CONSTRAINTS
If the individual is sufficiently protected from a source, then society is also protectedfrom that source.
However, there is a further duty to reduce doses, so as to achieve a higher levelof protection when feasible and practicable. This leads to authorised levels- OPTIMIZATION
22. This system of protecting individuals and groups is intended to provide a more
coherent basis for protection than the previous one. A necessary basic standard ofprotection from each relevant source is achieved for individuals by setting constraints
that are values of quantities, usually dose, but may be activity concentrations.
Constraints are usually annual values, but may be a single value depending on thecircumstances.
23. These constraints or basic levels of protection can be recommended by ICRP and
accepted internationally. The responsibility for optimization then rests with theoperators and the appropriate national authority. The operator is responsible for dayto-day optimization and also for providing input to the optimization that will establish
Authorised Levels for the operation of licensed practices. These levels will, ofnecessity, be site and facility dependent and beyond the scope of ICRP.
FACTORS IN THE CHOICE OF NEW CONSTRAINTS
24. The present system, which is unduly complex and has used at least six different
methods to determine the numerical values, has set maximum constraints that are,in general, about ten times the global average natural background. It is at aroundthis level that doses are usually deemed to require some action, whether they are forpractices or intervention, workers or the public.

6

25. The Commission now considers the starting point for selecting the levels at which any
revised constraints are set is the concern that can reasonably be felt about theannual dose from natural sources. The existence of natural background radiation
provides no justification for additional exposures, but it can be a benchmark forjudgement about their relative importance. The worldwide average annual effective
dose from all natural sources, including radon, as reported by UNSCEAR is 2.4 mSv.
26. A general scheme for the degree of concern and the level of exposure, as a fraction
or multiple of the average annual natural background, is shown in Table 3. The factthat the effective dose from natural background varies by at least a factor of ten
around the world, and even more if the highest radon doses are included, supports
the view that concern should begin to be raised at the higher end of the naturalrange.
27. At even higher levels of individual effective dose, i.e. more than 100 mSv in a year,
the risk from a source cannot be justified, except in extraordinary circumstancessuch as life saving measures in accidents, or in manned space flights. Individual
doses of the order of 500 mSv, if acute can cause early deterministic effects, or ifeither acute or delivered over decades, can cause significant probability of increased
cancer risk. This then becomes an individual-related restriction on dose and theappropriate authorities must ensure that the individual is not likely to receive
significant additional dose from other controllable sources.
28. At the other extreme, additional effective doses far below the natural backgroundeffective annual dose should not be of concern to the individual. Provided that theadditional sources come from practices that have not been judged to be frivolous,these doses should also be of no concern to society. If the effective dose to the most
exposed is, or will be, less than about 0.01 mSv in a year, then the consequent risk
is negligible and protection may be assumed to be optimized, thus requiring nofurther regulatory concern.
29. In the intermediate region, doses between a fraction of a mSv and a few tens of mSv,
whether they are received either singly or repeatedly, are legitimate matters forconcern, calling for action by regulatory bodies.

TABLE 3. LEVELS OF CONCERN AND INDIVIDUAL EFFECTIVE DOSE
RECEIVED IN A YEARGLOBAL AVERAGE ANNUAL NATURAL BACKGROUND EFFECTIVE DOSE FROM ALL
SOURCES IS 2.4 mSv (UNSCEAR 2000)
HIGH

More than 100 mSv

RAISED

More than a few 10s mSv

LOW

1 - 10 mSv

VERY LOW

Less than 1 mSv

NONE

Less than 0.01 mSv-

7

30. The challenge is whether fewer numbers could replace the 20-30 numerical values
for constraints currently recommended in Table 2. Further, could they also be more
coherently explained in terms of multiples and fractions of natural background.
OPTIMIZATION OF PROTECTION
31. The Commission wishes to retain the phrase ‘Optimization of protection’ and applies
them both to single individuals and to groups. However, it is applied only after
meeting the restrictions on individual dose defined by the relevant constraint. It is
now used as a short description of the process of obtaining the best level ofprotection from a single source, taking account of all the prevailing circumstances.
32. The Commission stated in Publication 77 that the previous procedure had become too
closely linked to formal cost-benefit analysis. The product of the mean dose and thenumber of individuals in a group, the collective dose, is a legitimate arithmetic
quantity, but is of limited utility since it aggregates information excessively. For
making decisions, the necessary information should be presented in the form of amatrix, specifying the numbers of individuals exposed to a given level of dose andwhen it is received. This matrix should be seen as a ‘decision-aiding’ technique thatallows different weightings of their importance to be assigned to individual elementsof the matrix. The Commission intends that this will avoid the misinterpretation ofcollective dose that has led to seriously misleading predictions of deaths.
33. The concept of collective dose was also previously used as a means of restricting theuncontrolled build-up of exposure to long-lived radionuclides in the environment at atime when it was envisaged that there would be a global expansion of nuclear powerreactors and associated reprocessing plants. Restriction of the collective dose perunit of practice can set a maximum future global per caput annual effective dosefrom all sources under control. If, at some point in the future, a major expansion of
nuclear power were to occur, then some re-introduction of a procedure may have to
be considered to restrict a global build-up of per-caput dose.
34. The process of Optimization may now be expressed in a more qualitative manner. On
a day-to-day basis, the operator is responsible for ensuring the optimum level ofprotection and this can be achieved by all those involved, workers and professionals,
always challenging themselves as to whether protection can be improved.
Optimization is a frame of mind, always questioning whether the best has been donein the prevailing circumstances. For the more formal authorisations, which aredecided by the regulator in conjunction with the operator, they may in future best be
carried out by involving all the bodies most directly concerned, including
representatives of those exposed, in determining, or in negotiating, the best level ofprotection in the circumstances. It is to be decided how the Commission’s
recommendations will deal with this degree of societal process. However, the resultof this process will lead to the authorised levels applied by the Regulator to thesource under review.
EXCLUSION OF SOURCES AND EXPOSURES
35. The Commission intends its system of protection to apply to the deliberate
introduction of a new controllable source or the continued operation of a controllable
source that has deliberately been introduced, i.e. a practice, and to controllable
natural sources. Its Recommendations can then be applied to reduce doses, wheneither the source or the pathways from the source to the exposed individuals can be8controlled by some reasonable means. Sources that do not fall within this definitionof controllable are excluded from regulatory control. There are sources for which theresulting levels of annual effective dose are very low, or for which the difficulty ofapplying controls is so great and expensive, that protection is already optimized andthe sources are therefore excluded.
36. In its restated policy the Commission defines what sources and exposures are to be
excluded from the system of protection and will not use the term ‘exemption’.
Exemption or clearance is seen as a regulatory decision that is applied to nonexcluded sources by the appropriate regulatory body. That body has the
responsibility for deciding when radioactive material is to be released from its control,
which is in effect an ‘Authorised Release’ no different from that specified for effluent
discharges after application of the optimization process.
37. Apart from these exclusions, the Commission has aimed to make its
recommendations applicable as widely and as consistently as is possible, irrespectiveof the origin of the sources. The Commission’s recommendations thus will now cover
exposures to both natural and artificial sources, so far as they are controllable.
NATURAL SOURCES
38. The Commission intends to include explicit recommendations for protection fromnatural radiation sources. It is clear that it is the controllability of the exposure that
determines whether the exposures are excluded from, or included in, the system ofprotection. In particular, the control of radon-222 is a special case because of its
ubiquitous nature.
39. The ICRP Recommendations for radon-222 in Publication 65 have been widely
accepted and the Commission proposes they should continue. These suggested amaximum level of dose (the constraint) that was translated into an activity
concentration, then followed by an activity concentration range within which an
optimized ‘action level’ would be found (Table 2). As now, the recommendation
would be that for exposures above this level, the system of protection is applied.
Exposures below the designated level are then excluded from the system ofprotection. The Commission now refers to this designated level as the Exclusion
Level.
40. The Commission is now considering an approach analogous to that for radon-222 forprotection from the other controllable natural sources. The principal sources of bothinternal and external exposure in environmental materials are potassium-40 and the
decay series of uranium-238 and thorium-232. The Commission is considering
recommending a maximum constraint for these, on the grounds that it is impracticalto control all natural sources. The constraint, as with radon, would not be expressedin dosimetric quantities but rather as an activity concentration, since that is more
appropriate and with a value at the upper end of the existing natural range. The
appropriate authority would apply generic optimization, or broad experience onpracticability, to find an Exclusion Level that is lower than the constraint.
41. The only protective actions are relocation of populations and, if the sources aremainly in building materials, extensive rebuilding. These actions are disruptive andrequire considerable resources. Thus the Exclusion Level, while lower than theconstraint, but probably not by more than a factor of a few, will be somewhere in thenaturally existing range, corresponding probably to dose of about a fraction of a mSv
annually.

942. Cosmic rays at ground level and the resultant exposures are not controllable. They
are therefore excluded from the scope of the Recommendations. Limiting the timespent by passengers and crew at high altitudes is the only action that could control
exposure to cosmic rays in aircraft. The average annual effective doses to someaircrew are about 3 mSv, while the exposure of some specialist aircrew and a few
professional couriers may be twice as high. The Commission has recommended in
Publication 60 that the exposures of aircrew in the operation of jet aircraft should betreated as occupational exposure in its system of protection. The Commission
considers that there is no justification for controlling doses to members of the publicfrom flying and these exposures should be excluded.
DOSIMETRIC QUANTITIES
43. There have been some persistent difficulties with, and misunderstandings of, thedefinitions of the Commission's dosimetric quantities. The Commission will remove
these by clarifying its definitions and specifying their application.
44. The Commission uses the weighted averaged absorbed dose in an organ or tissue.
It no longer uses the term ‘equivalent dose’ in order to avoid confusion with ‘dose
equivalent’ in translation to other languages. The implicit averaging is valid only if
the range of doses is such that the proportional dose-effect relationship applies.
There is no proposal to move away from the use of effective dose as currently
defined,E = Σ wT Σ wR DT,R
T

R

45. There is, however, a need to reconsider the basis used to derive the numerical values
for both the tissue and radiation weighting factors. There is evidence from a recent
report by a Task Group of ICRP Committee 1 that the wR values for protons andneutrons may need revision (ICRP 2003a). The 2001 UNSCEAR Report gives reduced
estimates of the risk of hereditary defects and another Task Group of Committee 1 isdeveloping proposals to simplify the way in which cancer risks are used to establish
wT values.
46. It should be emphasised that effective dose is intended for use as a protection
quantity and therefore should not be used for epidemiological evaluations, nor should
it be used for any specific investigation of human exposure. Rather, absorbed doseshould be used with the most appropriate biokinetic, biological effectiveness, and risk
factor data.
47. Those health effects that exhibit a dose threshold result from the loss of function of asignificant number of cells in a tissue. The dosimetric situation causing this loss offunction is complex. If the dose is approximately uniform over the tissue, the mean
absorbed dose is a good starting point. If the dose is far from uniform, the localised
damage may not reduce the performance of the tissue, but the localised damage
may be severe. All these situations depend heavily on the distributions of delivered
dose in position and time. This complexity cannot be reflected in the dosimetricquantities. The only approach is to make qualitative judgements based on the
distribution of absorbed dose in location and time. In many cases, there is no need to
introduce any weighting based on RBE, because its value will rarely exceed two.

10

RADIATION EXPOSURE OF PATIENTS
48. The application to the medical uses of radiation for patients requires separate
guidance. Limitation of the dose to the individual patient is not recommended as it
may, by reducing the effectiveness of the patient’s diagnosis or treatment, do more
harm than good. The emphasis is then on the justification of the medical procedures.
49. There are three levels of justification of a procedure in medicine. At the first andmost general level, the use of radiation in medicine is accepted as doing more goodthan harm. Its justification is now taken for granted. At the second level, a specified
procedure with a specified objective is defined and justified, e.g. chest radiographs
for patients showing relevant symptoms. The aim of this generic justification is tojudge whether the radiological procedure will usually improve the diagnosis ortreatment or will provide necessary information about the exposed individuals. At thethird level, the application of the procedure to an individual patient should bejustified, i.e. the particular application should be judged to do more good than harmto the individual patient.
50. The subsequent formal Optimization concentrates on the requirement to keep thedoses to patients as low as is consistent with the medical objectives. In diagnosis thismeans reducing unnecessary exposures, while in therapy it requires delivery of therequired dose to the volume to be treated, avoiding exposure of healthy tissues.
The generic justification of a defined medical procedure
51. The generic justification of the procedure is a matter for national professional bodies,sometimes in conjunction with national regulatory authorities. The total benefits froma medical procedure include not only the direct health benefits to the patient, butalso the benefits to the patient's family and to society. Although the main exposuresin medicine are to patients, the exposures to staff and to members of the public who
are not connected with the procedures should be considered. The possibility ofaccidental or unintended exposures (potential exposure) should also be considered.
The decisions should be reviewed from time to time, as more information becomes
available about the risks and effectiveness of the existing procedure and about newprocedures.
The justification of a procedure for an individual patient
52. For complex diagnostic procedures and for therapy, generic justification may not be
sufficient. Individual justification by the radiological practitioner and the referring
physician is then important and should take account of all the available information.
This includes the details of the proposed procedure and of alternative procedures, thecharacteristics of the individual patient, the expected dose to the patient, and theavailability of information on previous or expected examinations or treatment.
Diagnostic Reference Levels
53. These are used in medical diagnosis to indicate that, in routine conditions, the doseto the patient from a specified procedure should not normally exceed the reference
level for that procedure as indicated by a measurable quantity such as entry dose inan x-ray examination. These have already been used as Guidance Levels for medical
diagnostic procedures in the IAEA Basic Safety Standards and in the Euratom
Directive on health protection against ionizing radiation in medical exposure.

11

RADIOLOGICAL PROTECTION OF THE LIVING ENVIRONMENT
54. The current ICRP position regarding protection of the environment is set out in
Publication 60: “The Commission believes that the standards of environmental
control needed to protect man to the degree currently thought desirable will ensurethat other species are not put at risk.” Up until now, the ICRP has not published any
recommendations as to how protection of the environment should be carried out. The
Commission has recently adopted a report dealing with environmental protection(ICRP, 2003b). This report addresses the role that ICRP could play in this importantand developing area, building on the approach that has been developed for humanprotection and on the specific area of expertise to the Commission, namely
radiological protection.
55. The Commission has decided that a systematic approach for radiological assessmentof non-human species is needed in order to provide the scientific basis to support the
management of radiation effects in the environment. This decision to develop aframework for the assessment of radiation effects in non-human species has notbeen driven by any particular concern over environmental radiation hazards. It has
rather been developed to fill a conceptual gap in radiological protection and to clarify
how the proposed framework can contribute to the attainment of society’s goals ofenvironmental protection by developing a protection policy based on scientific andethical-philosophical principles.
56. The proposed system does not intend to set regulatory standards. The Commission
rather recommends a framework that can be a practical tool to provide high-leveladvice and guidance and help regulators and operators demonstrate compliance withexisting legislation. The system does not preclude derivation of standards, on thecontrary, it provides a basis for such derivation.
57. At present, there are no internationally agreed criteria or policies that explicitly
address protection of the environment from ionizing radiation, although many
international agreements and statutes call for protection against pollution generally,
including radiation. The current system of protection has indirectly provided
protection of the human habitat. The lack of a technical basis for assessment, criteria
or standards that have been endorsed at an international level, makes it difficult todetermine or demonstrate whether or not the environment is adequately protectedfrom potential impacts of radiation under different circumstances. The Commission’s
decision to develop an explicit assessment framework will support and provide
transparency to the decision making process.
58. A framework for radiological protection of the environment must be practical andsimple. The ICRP framework will be designed so that it is harmonised with its
proposed approach for the protection of human beings. To achieve this, an agreed
set of quantities and units, a set of reference dose models, reference dose-per-unitintake data and effects-analysis will be developed. A limited number of reference
fauna and flora will be developed by ICRP to aid assessments, and others can thendevelop more area- and situation-specific approaches to assess and manage risks to
non-human species. ICRP has a unique position in relation to human radiologicalprotection, from which it has played a major role in influencing legal frameworks andobjectives at international and national levels. In contrast, the subject of protectionof other species is more complex and multi-faceted, with many international andnational environmental legislative frameworks and objectives already in place.

1259. The Commission proposes that the objectives of a common approach to theradiological protection of non-humans organisms are to safeguard the environment
by preventing or reducing the frequency of effects likely to cause early mortality or
reduced reproductive success in individual fauna and flora to a level where theywould have a negligible impact on conservation of species, maintenance of
biodiversity, or the health and status of natural habitats or communities.
60. A considerable challenge for ICRP will be that of integrating any approach toprotection of the environment with that of the protection of human beings, bearing in
mind that the latter is also the subject of a current, in-depth, review. ICRP can, andis prepared, to play the key role with respect to ionizing radiation in the environment,
both in advising on a common international approach, and in providing the basic
interpretation of existing scientific information. This will include identifying where
further research is necessary - in order for such a common approach to be delivered.
SOME OUTSTANDING ISSUES AND PROPOSED TIMESCALES
61. The Main Commission is preparing a number of supporting documents on which themain recommendations will draw. These include summaries of the health effects ofradiation at low doses and the review of RBE values, which together will lead to a
document on the decision for revised radiation and tissue weighting factors. Other
major issues which are under development and need further discussion are;••••

Exploration into the possibility of specifying a fewer number of numericalconstraints than presently exist and whether they can be more coherently
explained
Clarification of the Exclusion concept and further elaboration of theobservation that all releases from regulatory control are ‘Authorised
releases’
A review of the ‘critical group’ concept as used to represent the
hypothetical individual. ICRP has not addressed this since well before the1990 recommendations.
Develop methods by which the optimization of protection can realisticallybeachieved

62. The intention is to have draft recommendations prepared for discussion with the fourCommittees late in 2003 so that a well-developed draft is available for the IRPA 11
Congress in May 2004. It is planned to produce the final version in 2005. Table 4shows a brief compilation of some of the major topics where there will be changes
from present recommendations to the new proposals.

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Table 4. Brief summary of essential changes expected in the new recommendations
TOPIC

Effective Dose
Radiation weighting factor

PRESENTRECOMMENDATIONS
Linear Non-Threshold
i.e. Proportionality
Yes
Publication 60

Tissue weighting factor

Publication 60

Nominal risk coefficient

Publication 60

LimitsConstraints

Worker and public in
Publication 60
See Table 2

Collective dose

Publication 60

Justification

Publication 60

Optimization

Cost-benefit analysis

Exemption
Definition of ‘individual’
Practice
Intervention
Environment (non-human)

Publication 60
Publication 29
Publication 60
Publication 60
Assumed protected in
Publication 60
Radon-222 only

Linearity

Natural radiation sources

NEW RECOMMENDATIONSClarify concept and applicablerange, i.e. above a few mSv/yr
Yes
Revised values for protons andneutrons
New values based on revised risk
factors and a simplified basis
Total Cancer Fatality similar, but
individual organs changed
Hereditary use UNSCEAR 2001
Incorporated into revised
constraints
Number and complexity to be
reducedDisaggregated and replaced byweighted matrix
Retained, extended for patient
exposure
Stakeholder involvement
Replace by Exclusion
New consideration
RetainIncorporate into constraints
Explicitly addressed
Comprehensive treatment

REFERENCESICRP Publication 37. Cost-Benefit Analysis in the Optimization of Radiation Protection,
Annals of the ICRP, Vol. 10 No2-3 (1983)
ICRP Publication 55. Optimization and Decision-Making in Radiological Protection, Annalsof the ICRP, Vol. 20 No 1 (1989)
ICRP Publication 60. 1990 Recommendations of the ICRP, Annals of the ICRP, Vol. 21 No
1-3 (1991)
ICRP Publication 62. Radiological Protection in Biomedical Research, Annals of the ICRP,
Vol. 22 No 3 (1993)
ICRP Publication 63. Principles for Intervention for Protection of the Public in a
Radiological Emergency, Annals of the ICRP, Vol. 22 No 4 (1993)
ICRP Publication 64. Protection from Potential Exposure: A Conceptual Framework,
Annals of the ICRP, Vol. 23 No 1 (1993)

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ICRP Publication 65. Protection Against Radon-222 at Home and at Work, Annals of the
ICRP, Vol. 23 No 2 (1994)
ICRP Publication 75. General Principles for the Radiation Protection of Workers, Annals of
the ICRP, Vol. 27 No 1 (1997)
ICRP Publication 76. Protection from Potential Exposures: An Application to Selected
Radiation Sources, Annals of the ICRP, Vol. 27 No 2 (1997)
ICRP Publication 77. Radiological Protection Policy for the Disposal of Radioactive Waste,
Annals of the ICRP, Vol. 27 Supplement (1998)
ICRP Publication 81. Radiation protection Recommendations as Applied to the Disposal ofLong-lived Solid Radioactive Waste, Annals of the ICRP, Vol 28 No 4 (1998)
ICRP Publication 82. Protection of the Public in Situations of Prolonged Radiation
Exposure, Annals of the ICRP, Vol. 29 No 1-2 (1999)
ICRP Publication zz. Relative biological Effectiveness(RBE), Radiation
Factor(wR ), and Quality Factor(Q). Annals of the ICRP (2003a) In press.

Weighting

ICRP Publication xx. A Framework for Assessing the Impact of IonizingRadiation on NonHuman Species. Annals of the ICRP. (2003b) In press.
UNSCEAR, United Nations Scientific Committee on the Effects of Atomic Radiation.
Sources and Effects of Ionizing Radiation, 2000 Report to the General Assembly,
E.00.IX.4, United Nations, New York (2000)
UNSCEAR, United Nations Scientific Committee on the Effects of Atomic Radiation.
Hereditary Effects of Radiation, 2001 Report to the General Assembly, E.01.IX.2, United
Nations, New York (2001)

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