Radiobiological Endpoints Relevant to Ecological Risk Assessment

Abstract

Because of the potential risk from radiation due to the releases of radionuclides from anthropogenic activities. considerable research was performed to determine for humans the levels of dose received. their responses to the doses and mechanisms of action of radioactivity on living matter. More recently, there is an increased interest in the effects of radioactivity on non-human species. There are differences in approach between risk assessment for humans and ecosystems. For protection of humans, the focus is the individual and the endpoint of primary concern is cancer induction. For protection of ecosystems, the focus is on population stability and the endpoint of concern is reproductive success for organisms important ecologically and economically. For these organisms. information is needed on their responses to irradiation and the potential impact of the doses absorbed on their reproductive success. Considerable information is available on the effects of radiation on organisms from different phyla and types of ecosystems. Databases useful for assessing risk from exposures of populations to radioactivity are the effects of irradiation on mortality. fertility and sterility. the latter two of which are important components of reproductive success. Data on radiation effects on mortality are available both from acute andchronic irradiation. In relation to radiation effects, reproductive success for a given populat ion is related to anumber of characteristics of the species. including inherent radiosensitivity of reproductive t issues and early lifestages, processes occurring during gametogenesis, reproductive strategy and exposure history. The available dataon acute and chronic radiation doses is reviewed for invertebrates, fishes and mammals. The informationreviewed indicates that wide ranges in responses with species can be expected. Parameters that most likelycontribute to inherent radiosensitivity are discussed.