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Exposures to ionizing radiation also arise from the use of radiation in rnedicine and
other activities. In most developed countries the radiation doses to populations from the
medical diagnostic uses of ionizing nadiation ane the largest of all the doses from artificial
sources. It is reasonable to assume lhat there will be an increase, and rnore divensity, in the
use of sources of ionizing radiation for medical purposes in the South Pacific Region as
health services develop f urther. In many countries in the Region the special facilities
necessary for these purposes are beeominq more readily available in the major population
centers, and it is to be expected that, with time, lhe facilities will be provided in less
densely populated areas. As these developmenLs occur, it will be imporLant for the countries
of the region to ensure thal the resulting.radiation doses to thein populations are minimized.
The Technical Group concluded that there would be value in the development of a regional
program through which pecial technicel services to oversee standards with respect to the
medical uses of ionizing radiation would be available. The medical uses of ionizing radiation
are the area in which countries have the greatest possibility of control over the radiation
doses received by their populations.
Present and proposed activities involvinq radioactive materials in the South Pacific reoion
After a brief review of radioactivity in the Pacific Ocean, and of the behavior of
radionuclides in the marine environrnent, the Technical Group Report proceeds to a discussion
of activities presently conducted in the Region, or proposed for the future, that might result
in the release of radionuclides Eo the environment. The activities that are presently of
greatest concern and most likely to influence the setting of environmental policy in the near
future are the underground nuclear explosions presently being conducted in the Tuamotu
Islands by France, as part of iLs weapons development program, and the proposed use of the
Pacific Ocean for Lhe disposal of radioactive wasLes.
Regarding the question of radioactive waste disposal, the Report includes an extended
discussion of the ocean dumping of packaged low-level waste, because there has alreaciy been
considerable development of a scientific basis for setting limits on such disposal and because
there exist well-developed intennation.al mechanisms for control and zurveillance.
Furthermore, a specific proposal has been issued by Japan to initiabe in the near future a
program of low-level waste disposal a! a site in the western North Pacific, and this proposal
has been the focus of considerable debate in the Region over the general issue of ocean
dumping.
Discussion of Lhe scientific issues related to ocean dumping begins with the fact that
ppreciable amounts of radionuclides are continually delivered to the oceans by natural
processes. The question that is open to scientific debate is a quantitative one and the
scientific task is to provide a quantitative answer: What additional amounts of redionuclides,
if any, can be added to the ocean without a risk to the environment or to human health that
exceeds the standards set by society? Tl-e answer is based on the results of scientific
research, which is a continuing process, so the answer is always (as it should be) subject to
revision as improved scientific knowledge watrants. Because of lhis, a conservative but
flexible approach should be taken.
The International Atomic Energy Agency (lAEA, 1978arbrc) provided a general
assessrnent of the problem of ocean dumping. lts task was to set limits on the release rates
of radionuclides on the seafloon so that a definition of high-level waste (not suitable for
dumping) could be formulated as required by the Lmdon Dunping Convention. In its
assessrnent the IAEA used quantitative predictions of the dose equivalent to people as a
measure of the impact of durnping. The IAEA scientists recognized that present scientific
knowledge does no! allow exact predictions of seawater concentrations resulting from
radionuclide releases to be made. Tfrey also recognized the possibility that some radioactivity
could be transferred from the seafloor to human populations by completely unforeseen
pathways. Because of these uncertainties, they adopled a conservative approach based on
pessimistic assumptions about what might happen in extreme circumstances, not on realistic
assumptions about what would most likely happen under ordinary circumstances. Thus the
doses predieted by their calculations are, by intention, most probably overestimated. For this
reason the resulting release-rate limits contain built-in safety factors. The Technical Group
concluded that a very high level of conservatism was adopted in the IAEA assessment and
that the release-rate limits set by IAEA are restrictive enough that dunping carried out
within the IAEA guidelines should pose extremely little risk to human health or environrnental
safety.