Radiation & the environment: Assessing effects on plants and animals

The international body known as the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) periodically reviews the effects of ionizing radiation on the environment. Last year, the Committee, for the first time, issued a report that contained a review specifically focused on the effects of ionizing radiation on plants and animals.* While the review contained no surprising findings, it does serve to focus attention on the changing nature of the scientific community's assessment of radiation's potential environmental effects. Previously, scientific assessments had considered plants, animals, and other living organisms as part of the environment in which radionuclides become dispersed. They were further seen as resources which, when contaminated, may contribute to human radiation exposures since some plants and animals are elements of food chains and represent pathways for the transfer of radionuclides to humans. In brief, the assessments reflected the generally accepted position that priority should be given to evaluating the potential consequences for humans — which are among the most radiosensitive mammalian species — and to providing a sound basis for protecting human health. This position, however, has been questioned recently. It has been shown that there is at least one situation — namely in deep-sea sediments, an environment very remote from humans — where the above accepted priority could be incorrect.** Detrimental effects on the environment also have been observed in localized areas as a consequence of plants and animals having received short-term, very high radiation doses following major accidental releases of radionuclides. This has been the case, for example, in areas affected by the 1957