Radio Ecological Benchmarks for the Ecological Risk Assessment of Radioactive Waste Management Facilities

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Nava C. Garisto

Abstract

Ecological risk assessments are used to assess potential ecological impacts from contaminated sites, such as radioactive waste management and disposal facilities. These assessments determine the overall significance of the impact of such facilities on non-human biota. Specific indicator species are selected as representative non-human biota at the study sites for the purposes of these risk assessments.


Potential environmental impacts are generally assessed in terms of 'screening indices'. In simple terms, a screening index is the ratio of an estimated exposure level of the indicator species (or environmental concentration) divided by a level or concentration deemed unlikely to have a significant ecological effect. These latter levels or concentrations are referred to as 'estimated no effect value' or ENEVs. Nominal ENEV values for chronic radiation effects based on our current interpretation of literature data are presented in this paper. They are: 5 mGy/d for fish and amphibians; 2.4 mGy/d for aquatic plants; 2 mGy/d for reptiles; 5 mGy/d for benthic and terrestrial invertebrates; 1 mGy/d for slow-growing terrestrial animals that reproduce late in life; 10 mGy/d for short-lived prolific terrestrial animals; 2.4 mGy/d for terrestrial plants; 5 mGy/d for birds. The paper identifies major areas of uncertainty regarding the selection of these nominal ENEVs for practical applications.

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