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ICRP: Free the Annals!

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Submitted by Judith Johnsrud, The Sierra Club, Radiation Committee
   Commenting on behalf of the organisation
Document Foundation docs Optimisation; Dose to Individual
 
Comments submitted on behalf of the U.S. Sierra Club, Radiation Committee, on:
ASSESSING DOSE OF THE REPRESENTATIVE INDIVIDUAL FOR
THE PURPOSE OF RADIATION PROTECTION OF THE PUBLIC
July 8, 2005

The Sierra Club is appreciative of the ICRP’s soliciting comments from
stakeholders -- the overwhelming majority of whom are members of the public
-- on ICRP’s foundation documents
for the Commission’s 2005 draft Recommendations. It is our understanding
that the ICRP has withdrawn its draft Recommendations for full revision, in
response to the extensive criticisms filed in late 2004, a commendable
decision.

For the purpose of determining permissible radiation exposure limits
for the public, the use of the concepts of both a “critical group” and,
based on that selected sub-population, a “hypothetical representative
individual” within the critical group is not an acceptable approach for
assuring adequate radiation protection for real individual members of the
public. Acceptable radiation protection cannot be based on unverified
assumptions, averages, estimates, uncertainties, hypotheticals,
theoreticals, reasonableness, unsubstantiated inferences, ”relatively
conservative assessments,” or “avoidance of excessive conservatism,” to
name only a few such terms used in this document.

Nor is comparing the assumed and calculated factors applied to the
“representative individual,” as described in this document, with the “dose
constraint” previously established in the Commission’s 2005 Recommendations
an approach that will assure adequate real protection for real individuals.

It is noteworthy that the document excludes occupational and medical
exposures and is addressing only doses for members of the public. It is
therefore unclear how ICRP is considering the additive exposures received
by workers from sources they encounter as members of the public, or the
additive doses from medical practices that are received by members of the
public and by workers – in other words, the total radiation exposures
experienced by individuals from all sources. Those sources and doses may
be properly described as multiple, additive, cumulative and
synergistic. With respect to the totality of doses actually received, this
issue is of particular significance at the present time, when regulatory
agencies are proposing to release large amounts of radioactively
contaminated materials and wastes from regulatory control and permit them
to be recycled and reused, potentially in consumer products. They may also
be allowed to be disposed of in ordinary municipal solid waste landfills
not designed to maintain appropriate control, or they may be allowed to be
incinerated in increasing quantities. The prospective analysis that
predicts larger future sources of exposure is of particular importance in
today’s radiation protection.

The task of devising sufficiently accurate and complete criteria for
standards is unquestionably difficult, but the ranges, the uncertainties,
and unstated assumptions here render this foundation document disturbingly
inadequate. At base is an unstated assumption that there are doses of
ionizing radiation, in addition to naturally occurring exposures, that are
“safe” for members of the public who will receive no benefit, nor any
benefit that is greater than or commensurate with the additive risk of
damage incurred. Yet the U.S. National Academies of Science Committee on
the Biological Effects of Ionizing Radiation BEIR VII Report, released on
June 29, clearly states that the linear no-threshold dose-response
hypothesis continues to be accepted. The thrust of this long-awaited
report is a reconfirmation of the BEIR V Committee’s 1990 conclusion that,
so far as they could determine, there is no “safe” level of radiation
exposure.


Consonant with this finding is a mounting body of research in the
allied field of radiation microbiology that is identifying some previously
unrecognized mechanisms of radiation damage at very low doses. Some of
this recent research is well described in the ICRP Committee 1 Task Group
2005 draft Report, titled “Low-dose Extrapolation of Radiation-Related
Cancer Risk.

These current research findings on delayed mutational effects, genomic
instability, double strand breaks, chromosomal aberrations, imperfect
repair, and bystander effect have led some of those scientists to the
conclusion that a single radiation track through a cell is sufficient to
initiate any of a number of injuries that may prove carcinogenic or result
in other forms of biologic damage.

In Table 3 of the text under the probabilistic calculation method, it
is stated that the representative individual “is identified such that the
probability is less than about 5% that a person drawn at random from the
hypothetical population will receive an annual effective dose exceeding the
dose constraint. This seems a rather deceptive way of stating that some 5%
of the population could be allowed to receive an annual effective dose that
is higher than the dose received by the so-called representative individual
– apparently a dose higher than permissible. If this is not the case, a
revised wording to clarify would be helpful.

Perhaps the most disturbing aspect of this foundation document is its
continuing failure to differentiate sufficiently among the variabilities of
individuals in our species. Particularly distressing is the
ICRP’s decision, in the name of simplification (3.4), to reduce the number
of age categories to merely three, concluding that “an appropriate level of
protection can be achieved by comparing the assessed dose to the foetus or
breast-fed infant with the dose limit for members of the public.” A member
of the public a new-born baby indeed is, but it is also more sensitive than
an adult, or than a ten year old child. It is long overdue for the ICRP to
give proper recognition to differential sensitivities and vulnerabilities
among the differing segments of exposed populations. The use of
“representative individual” doesn’t do it.

This foundation document does discuss the importance of
characterization of environmental factors related to both external and
internal exposures. However, reliance is on dose assessments within the
framework of the “critical group” that is presumably homogeneous in part
due to the spatial homogeneity of the geographic locus of the group –
similar geologic, atmospheric, temperature, and hydrologic conditions,
similar foodstuffs, shelter, etc. In the real world, as is admitted,
conditions and situations of individuals are highly variable. The goal of
protecting populations from radiation injury should not be based on a
static and unrepresentative “representative individual” – any more than
radiation standards in the U.S. should continue to be based on “standard”
or “reference” man, who, as he is defined, may be in the least sensitive
sector of the exposed population.

Radiation protection worldwide would be enhanced by abandoning the
dose constraint approach that in turn relies on the representative
individual within the critical group. ICRP states at the outset that its
recommendations are intended to give more emphasis to the individual,
rather than to society as a whole. The goal is commendable; the means of
achieving it as described in this document do not succeed. The paradigm
shift now occurring in the field of low-level radiation biology suggests
that adoption of the precautionary principle – setting dose standards far
more restrictive than current ones – would be the prudent course of action
for ICRP