SREL Reprint #2203

A screening model approach to determine probable impacts to fish from historic releases of radionuclides

T.G. Hinton and F.W. Whicker

Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA

Abstract: The term "ecological risk assessment" is often used to describe studies of contaminant concentrations, toxicity tests, or other components of ecotoxicological research. Absent in many of theses studies is the "risk assessment" component (i.e. the risk factor), which by definition equates exposure to a probabilistic prediction of a harmful effect (based on knowledge of exposure pathways and biological damage). This risk factor is the critical key in a risk assessment. Risk factors, however, do not generally exist for aquatic organisms, therefore, complete risk assessments are difficult to perform. We tried an alternative approach of using a screening model, and tested the concept by calculating dose to a fish population that has inhabited radionuclide contaminated waters on the Savannah River Site since 1954. The model input parameters were conservatively chosen so that fish dose was maximized. Ingestion and external irradiation from contaminated sediments and the water column due to 3H, 60Co, 90Sr, 131I, 137 Cs and 239Pu were considered. Combining the dose from the six radionuclides across all pathways resulted in a dose rate to the fish of 0.23 mGy d-1. Having estimated a dose rate, but lacking the necessary risk factors to perform a risk assessment, we compared our calculated dose to dose rates in the literature that have documented effects associated with chronic exposures. This comparison allowed us to qualitatively predict the probability of (1) mortality and (2) physiological effects encountered by the exposed fish population.

SREL Reprint #2203

Hinton, T.G. and F.W. Whicker. 1997. A screening model approach to determine probable impacts to fish from historic releases of radionuclides. Freshwater and Estuarine Radioecology: 425-432.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).