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 radio-biological 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
