Estimation of waterborne selenium concentrations that are toxicity thresholds for wildlife

Abstract

Contamination of freshwater systems can lead to mortality and impaired reproduction in wildlife. There is a growing need for methods to estimate waterborne contaminant concentrations that pose an unacceptable risk to semi-aquatic and terrestrial vertebrates that use aquatic habitats. Single-species toxicity data, information on contaminant bioaccumulation in aquatic food webs, and energy-based estimates of contaminant exposure to sensitive birds and mammals were used to estimate waterborne selenium levels that are toxicity thresholds for wildlife. Threshold estimates for birds and mammals with food habits that likely lead to high exposure to bioaccumulative contaminants in aquatic systems (e.g., piscivorous birds and mammals) were about 1 μg/L (ppb) waterborne selenium (dissolved selenium). The estimates are near the low end of toxicity thresholds developed by other investigators using different methods. The model may be a useful tool for estimating risks waterborne environmental contaminants pose to aquatic wildlife.