Observations carried out in the frame of the ISTC project 3547 [1] were used to parametrize and validate the model of radionuclides transport from Siberian Chemical Combine (SCC) by the Tom and Ob rivers and also to assess discharges of radioactive substances from SCC to the Tom River and to estimate possible contamination of the rivers in case of accidents.

There is general international acceptance of the need to demonstrate that the environment is protected from ionising radiation. In some countries requirements and guidelines for the protection of non-human biota are already in place. As a consequence a number of models and approaches have been proposed for the estimation of the exposure of non-human biota to ionising radiation. The IAEA EMRAS programme's Biota Working Group has conducted the most comprehensive intercomparison of the predictions of these approaches to date. In this paper, we present an overview of the activities of the Biota Working Group concentrating on its conclusions and recommendations.

In the radiobiological studies of aquatic organisms, fish eggs are a favorite subject for experimental work because of easy availability of embryos and the possibility of observing the development of embryos within eggs. Data from Russian/FSU publications concerning the effects of ionizing radiation on the survival and development of fish eggs were compiled within the framework of the EC Project EPIC “Environmental Protection from Ionizing Contaminants in the Arctic" (2000-2003). Comparative analysis was performed for effects on roe of two representative fish species: cold-water fish salmon (Salmo salar), and pike (Esox lucius), which is widespread predatory fish from the temperate climatic zone.

In this paper we use the FASSET framework to estimate absorbed dose rates for biota within the Chernobyl exclusion zone. The estimated doses are compared to observed biological effects within the Chernobyl exclusion zone and effects expected from summaries of existing knowledge and the extent of contamination. Although paucity of observations under conditions of chronic irradiation makes direct comparison difficult, the biological effects observed in the Chernobyl exclusion zone over the period considered here (1988-2003) are broadly in agreement with those which may have been expected.