FYI, copied from another listserv...
Jaro
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Sent: Sunday June 15, 2003 11:31 AM
To: cdn-nucl-l (E-mail)
Subject: [cdn-nucl-l] UNSCEAR Back on the Job, Jaworowski letter in Physics Today, June 2003
UNSCEAR Back on the Job
After two years of hibernation, the United Nations Scientific Committee on
the Effects of Atomic Radiation is up and running again. It finally met in
January 2003, in Vienna. UNSCEAR's paralysis was due to budget cuts by the
United Nations Environment Programme, which funnels funds from UN
headquarters to the committee. For several years, UNEP had decreased
UNSCEAR's funding, and in 2002, that lack of funding virtually halted the
committee's activities. Several scientific publications raised an outcry
(see, for example, Physics Today, October 2002, page 26), and brought
UNSCEAR's case to the public.
At the end of 2002, the General Assembly urged UNEP to review and strengthen
UNSCEAR's funding levels. The flow of funding was thus restored. The driving
force behind UNSCEAR's resurrection is its new scientific secretary,
radiobiologist Norman Gentner.
The mood of UNSCEAR has changed, as reflected in its increasing reservation
toward the use of dose commitment (individual dose from a practice--nuclear
explosion, reactor operation, medical use of radionuclides, or natural
radiation, for example--integrated over infinite time and all future
generations) and collective dose. Both are offspring of the
linear-no-threshold model of radiation effects. The LNT model, on which the
current radiation protection recommendations are based, assumes that even
the lowest, near-zero dose of radiation can be detrimental, that the risk
per unit dose is constant and additive, and that the risk can only increase
with dose. Recent radiobiological and epidemiological studies suggest that
this model has lost credibility.[1] During its 2003 session, UNSCEAR
reviewed 10 draft documents, the most important ones discussing occupational
radiation exposure and exposure of the general public, radioecology,
epidemiology of radiation-induced cancers, and health effects of the Chernobyl accident.
The Chernobyl document is a high priority and is expected to be published in
2006. Thyroid tumors will be studied with extra care. The committee decided
to base its analysis on both the thyroid cancer incidence data (less
certain) and on the thyroid cancer death rate. The psychological effects of
the catastrophe, especially on children exposed to radiation in utero, will
be studied, as will clinical genetic disorders.
Six years ago, UNSCEAR published a report on the environmental effects of
radiation; the document fully covered the knowledge available at the time.
It concluded that no evidence exists of any local population of a single
species having been eliminated as a consequence of radiation exposure.[2]
Since that report, little has changed. The 2003 draft document on
radioecology apparently addressed the new policy of the International
Commission on Radiological Protection (ICRP) of protecting not only nonhuman
species but also nonhuman individuals against ionizing radiation. The old
policy was based on the rather obvious assumption that if man is protected
as an individual, then other living things are also protected as species.
Radiation researchers are now expected to spend more time and resources to
learn the effect of anthropogenic radiation on individual plants and
animals. However, it is well known that, in Kerala, India, where the natural
radiation level (up to about 400 millisieverts per year) is much higher than
the average global one (2.4 mSv), black rats for 800 to 1000 generations
have shown no adverse biological effects.[3] The new policy will likely
confuse both the public and the regulators who are developing guidelines for
biota. It will complicate decision making and increase the cost of radiation
protection far above its present level for protecting humans. I sincerely
hope that the committee will resist the pressure of environmentalists and
return to its traditionally neutral, independent, and rational position on this topic.
In the past, UNSCEAR helped resolve basic issues concerning the effects of
ionizing radiation on humans and the environment. Results of its studies
became the foundation for radiation protection systems from the ICRP and
other organizations. I argue that the current system based on the LNT model
will collapse, because it is overly complicated, enormously costly to
society, and now overshadowed by knowledge gained over the past decade.
UNSCEAR's task is to supply a scientific foundation for a new radiation
protection system. One issue is the known hormetic (beneficial or positive),
adaptive, biphasic response of cells and organisms to radiation dose.
Implications of that universal biological phenomenon for economics, risk
assessment and risk communication to the public, clinical medicine, and
regulatory strategies have recently been presented in a brilliant commentary in Nature.[4]
References
1. See, for example, R. E. J. Mitchel, D. R. Boreham, Proc. of the
International Radiation Protection Association, 10th Quadrennial Meeting,
Hiroshima, Japan, 15-19 May 2000, Plenary Session 1.
2. UNSCEAR, Sources and Effects of Ionizing Radiation, UNSCEAR, New York
(1996).
3. P. C. Kesavan, in High Levels of Natural Radiation, L. Wei, T. Sugahara,
Z. Tao, eds. Elsevier, Amsterdam (1996), p. 111.
4. E. J. Calabrese, L. A. Baldwin, Nature 421, 691 (2003) [MEDLINE].
Zbigniew Jaworowski
(jaworo@clor.waw.pl)
Central Laboratory for Radiological Protection
Warsaw, Poland
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