Margins of uncertainty in ecotoxicological hazard assessment

Abstract

AbstractMargins of uncertainty in predicting toxicity from one species to another, from acute to chronic exposures and from single species to higher levels of biological organization were determined by regression and correlation analyses. Based on the acute sensitivities of 35 aquatic species to 15 compounds, no species was found to be particularly sensitive to all chemicals and the 95% uncertainty factor (UF) ranged from 3 to 1,985. Analyses of acute and chronic sensitivities for the same species to 164 chemicals resulted in the acute/chronic relationship log NOEC = ‐1.28 + 0.95 log L(E)C50 (r = 0.89) and the UF of 25.6 (where NOEC is the no observed effect concentration). Comparison of the lowest acute and corresponding ecosystem effect levels for 34 chemicals indicated the relationship log NOEC(ecosystems) = ‐0.55 + 0.81 log L(E)C50 (r = 0.77) and the UF of 85.7. As to the predictability of ecosystem effect levels from chronic single‐species data, the following relationship was found: log NOEC(ecosystems) = 0.63 + 0.85 log NOEC (r = 0.85), with a UF of 33.5. These data indicate that acute testing is not pointless; it offers a statistical base for the use of acute toxicity information in the hazard assessment of chemicals in the aquatic environment.