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 my
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. p. 425-432. In Freshwater and Estuarine
Radioecology, edited by G. Desmet.
