R.V. Osborne 1

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Are the Proposed Recommendations of the
International Commission on Radiological
Protection Taking Us in the Right
Direction? Richard V. Osborne Robert S.
Landauer, Sr. Lecture 49th Annual Meeting of the
Health Physics Society Washington, DC, 2004 July
11-15
PL1.1
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The Right Direction . . .
. . .if you dont know where you are going,
chances are you will end up somewhere
else. Yogi Berra
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The Right Direction . . .
What do we hope to be able to say of the new
recommendations?
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The Right Direction . . .
Changes are evolutionary, not revolutionary. Scien
ce base is sound. Concepts, quantities, and
vocabulary are clear. Role of justification is
clear. Application of limits and constraints is
clear. Misuse of collective dose is
avoided. Categories of exposure are more
helpful. System is linked to mainstream risk
assessment and management. Recommendations are
accepted as authoritative.
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The Right Direction . . .
How do the draft recommendations measure up
against this vision?
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Draft ICRP 2005 Recommendations
Stated aims Consolidate and clarify decade of
ICRP recommendations. Remain consistent with
other international guides and standards. Suggests
intent is evolutionary, not revolutionary. Move
from a utilitarian approach to protection to one
based on the individual. Taken as a given that
this is right - should be challenged.
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The Right Direction . . .?
Consider here under the headings Science
base Quantities and concepts Principles
Justification Dose limits and
constraints Optimisation of
protection Application Environment
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Science base
Deterministic effects ...Tissue/organ
reactions Detailed analysis of current
literature.
Conclude No thresholds for tissue reactions
below tens of mGy.
Stochastic effects..Cancer
development Heritable disease

• Key question Does the current epidemiological
  and experimental body of knowledge lead to a
  different model?

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Science base
ICRP considered Epidemiological evidence Complex
nature of radiation-induced DNA damage Adaptive
response Genomic instability Bystander signalling
. . .

• Concluded
• Despite extensive body of evidence, uncertainties
  too great to judge influence on low dose cancer
  rate.

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Science base
. . . for the purposes of radiological
protection, the Commission judges that the weight
of evidence on fundamental cellular processes
supports the view that in the low dose range up
to a few tens of mSv, it is scientifically
reasonable to assume . . . for practical purposes
cancer risk will rise in direct proportion to
absorbed dose . . . ICRP 2005, para. 101
This is a key assumption Allows sources of
exposure to be controlled independently. Protectio
n concepts and quantities remain valid.
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Quantities and concepts
Radiation protection quantities Equivalent dose
Wr x Average absorbed
dose (sievert)
(gray) Effective dose Wr x Wt x Average
absorbed dose (sievert)
(gray)
Radiation weighted dose (??????)
(Operational quantity Dose equivalent remains)
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Quantities and concepts
Changes in radiation weighting factors
wr Protons..Reduced from 5 to 2 Neutronslt
1Mev, reduced by 50
Implications Nuclear power plant workplace
spectrum Reduction in wr by 23 (c.f.
ICRP26 to ICRP60, increase of 55) A.
Waker, private communication
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Quantities and concepts
Tissue weighting factors wt and nominal risk
coefficients Based mainly on the Life Span
Study (incidence data). Same value for the Dose
and Dose Rate Effectiveness Factor (DDREF) as in
ICRP 60.
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Quantities and concepts Tissue weighting factors
wt
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Quantities and concepts Tissue weighting factors
wt

• Bone marrow
• Colon
• Lung
• Stomach

0.12
Skin Bone surface
0.01
Brain Kidney Salivary glands
Breast
Breast Bladder Liver Oesophagus Thyroid
Remainder
0.05
0.05
Remainder (Applied to average dose to 14
tissues)
Gonads
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Quantities and concepts
Slight reduction in detriment coefficients
(/Sv) Whole population 7.3 Adult
workers 5.6
Caveat on effective dose and nominal risk
coefficients.

• Dont use for
• Estimating risks retrospectively for
  individuals.
• Epidemiological purposes with populations.

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Principles Justification
Acknowledges radiological considerations may be
only minor part of justification of practices.

• Justification of radiation-related medical
  procedures remains important principle within
  the scope of radiological protection.
• More good than harm to patient and account taken
  of detriment to staff and others.

Appears to be a helpful clarification.
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Principles Dose Limits and Constraints
Adapted from ICRP2005
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Principles Dose Limits and Constraints
Adapted from ICRP2005
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Principles Dose Limits and Constraints
ICRP 60 values of the dose limits are
retained. Limits continue to be used for the
level of protection for individuals from all
regulated sources only in normal situations.
Dose constraints are much more important . . .
the fundamental level of protection . . . where
action to avert exposures and reduce doses is
virtually certain to be justified.

• Quantified for all controllable situations
• Normal sources
• Existing exposures
• Emergencies

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Principles Dose Limits and Constraints
Natural radiation background a benchmark for
judgement about . . . relative importance of
added exposures and the need for action.

• Basis for recommended maximum values for dose
  constraints

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Principles Dose Limits and Constraints

Recommended maximum values for dose constraints
on single sources
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Principles Dose Limits and Constraints
Four values of dose constraints selected to be
consistent with the current scheme.
Still need variety of constraints for variety of
circumstances. More detailed consideration of
types of public exposure would help. Helpful in
countering the idea that the same limit has to
apply in every situation.
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Principles Dose Limits and Constraints
Dose constraints not explicitly related to
nominal risk.
For potential exposures and risk constraints
need to cite risk associated with dose
constraint. Annual constraints or one-off?
Basis for limits was life-time risk. Constraints
are expressed as annual doses.

• Fundamental change in basis for control.

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Principles Dose Limits and Constraints
Comparison with natural background
Attempts to combat exaggeration of significance
of low doses. Exaggerates the significance of
more than a few mSv
May be misapplied as justifying (or not)
particular exposures. Weak basis for the
fundamental control levels.

• Diminishes the science base.
• May reduce credibility.

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Principles Dose Limits and Constraints
Comparison with natural background Unintentional
message may be There is concern about doses
above natural background.

• rather than
• The effect on health of low doses of radiation
  is overwhelmingly likely to be zero.

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Principles Optimisation of Protection
Complements constraints. (Importance seems to be
reduced.) Emphasis is on protecting
individuals. (Societal or utilitarian aspects are
downplayed.)
Optimisation is said to be broader than ALARA.
. . . protection and safety issues receive the
attention warranted by their significance. .
. . consideration of the avoidance of accidents
and other potential exposures The involvement
of stakeholders . . . is an important input . . .
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Principles Optimisation of Protection
Optimal protection results when exposures to
individuals . . . represent the best choice in
the the prevailing circumstances.
Exposures in workplace should be ALARA, social
and economic factors taken into account. but . .
. Control of emissions should be best available
technology not entailing excessive costs . . .
with due consideration to social and economic
factors.

• ALARA could be said to include all these.
• No caveats on stakeholder involvement.

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Principles Optimisation of Protection
Steers away from using collective dose as such in
the protection of groups.
The dose matrix idea Number of exposed
individuals Magnitude of individual doses Dose
distribution in time Age- and sex-dependent
modifiers Equity considerations Real or potential
exposures
Not clear what the underlying principle is.
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The Right Direction . . .
ICRP seem to be caught between two maxims
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The Right Direction . . .
We must adjust to changing times and still hold
to unchanging principles. President
Jimmy Carter
It is a terrible thing to look over your
shoulder when you are trying to lead - and find
no one there. President Franklin D.
Roosevelt
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Application
System of protection applies to controllable
sources . . . either the source of exposure or
the pathways leading to the doses received by
individuals can be controlled by some reasonable
means.
Not a clear definition.
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Application
Exclude from the system of protection Cosmic
rays at ground level, potassium-40 in
body Artificial radionuclides (low end of
internationally-exempted
concentrations).
alpha emitters 0.01 Bq/g
beta/gamma emitters 0.1 Bq/g
Natural radionuclides (high end of natural range).
uranium-238/thorium-232 1
Bq/g potassium-40 10 Bq/g
Confusion of exclusion and exemption. Values may
preclude higher exemption values for particular
purposes. Simple screening approach might be
better.
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Environment
Responding to criticism that previous position
not substantiated . . . protect man . . .
protect environment . . .

• Adopts principles as developed by IAEA
  (sustainability, biodiversity, habitat protection
  . . .).
• Aims for consistency with human protection.
• . . . radiation levels where action is needed
  and with explicit reference to natural background
  dose rates.

Implicitly suggests concern at few times natural
background? This seems much too restrictive.
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Environment
Suggest developing reference biota
dosimetry models environmental geometries life
cycle biology pathways to exposure

• Useful basis for deriving ambient activity
  levels.
• Overall system of protection to parallel that for
  people.
• May be better to aim for closer harmonisation
  with current environmental protection practice.

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Are the Proposed Recommendations of the
International Commission on Radiological
Protection Taking Us in the Right Direction?
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The Right Direction?

Interpretation of science..yes Termino
logy and concepts. yes/no Adjustment
of quantities. yes Clarification of
Justification . yes Emphasis on dose
constraints rather than limits yes but . . .
basis of annual natural background.. no Emphasi
s on broad-based optimisation... yes but .
. . advice on implementation... no
continued . . .
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The Right Direction?

Excluded activity concentrations... maybe
Development of tools for biota protection.yes
but . . . framework development.. no Ev
olutionary not revolutionary... yes
but . . . overall direction no Consult
ative process... yes
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The Right Direction?

Review and comment by the end of 2004
www.icrp.org
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