Selenium toxicity to aquatic life: An argument for sediment‐based water quality criteria

Abstract

AbstractA number of streams in Colorado were found to contain waterborne selenium concentrations that consistently exceeded the current U.S. EPA chronic criterion of 5 μg/L and often exceeded the acute criterion of 20 μg/L. Despite these elevated concentrations, no biological impact was observed. These findings led to a review of selenium exposure pathways in freshwater. The literature strongly indicates that chronic selenium toxicity can result from accumulation of selenium in the sediment, movement into the food chain, and resulting dietary uptake. Chronic toxicity does not appear to be strictly a result of waterborne selenium concentrations. In fact, dissolved selenium concentrations are a poor predictor of potential chronic toxicity to freshwater organisms, when evaluated with Hill's criteria for causal association. To develop a more reliable chronic waterborne criterion, a sediment‐based method is needed to describe accurately potential chronic toxicity of selenium on a site‐specific basis.