[en] The Environment Agency has a legal requirement to assess the impacts of permits for discharges affecting Special Areas of Conservation (SACs) or Special Protection Areas (SPAs) under the Habitats Regulations (1994), including the assessment of radiological risk. As there is no international consensus on the approach to be taken to assess the impact of ionizing radiation on wildlife, the Environment Agency has developed guidance to satisfy its regulatory obligation, based on a published impact assessment methodology. This approach will also feed into the European Commission funded project Framework for ASSessment of Environmental ImpacT (FASSET), due to complete in October 2003. The impact assessment approach focuses on three ecosystems representative of those considered potentially most at risk from the impact of authorized radioactive discharges, namely a coastal grassland (terrestrial ecosystem); estuarine and freshwater ecosystems. Dose calculations have been programmed into spreadsheets to support the methodology. The approach also makes recommendations on the relative biological effectiveness of different types of radiation with respect to wildlife. Evidence for effects at low dose rates is reviewed and Tables of experimental and field study data on the effects of ionizing radiation are presented with which to compare any predicted doses to wildlife in order to assist in the impact assessment process. Information reviewed indicates that it is unlikely that there will be any significant effects in: terrestrial animal populations at chronic dose rates below 40 μGy/h; terrestrial plant populations at chronic dose rates below 400 μGy/h; populations of freshwater and coastal organisms at chronic dose rates below 400 μGy/h. The guidance make use of the methodology at various stages of the review process. It is also important to recognise that the assessor must consider the assumptions and constraints in the methodology, especially in the case of site-specific features, such as the presence of rare or endangered species. Finally, the above levels have been adopted within the guidance for the present time, but will be reviewed in the light of FASSET's radiation effects database. (author)