A Data Based Comparison of Single Species and Model Ecosystems Sensitivity. D. J. Versteeg, The Procter & Gamble Company; S. E. Belanger, Ivorydale Technical Center; and G. J. Carr, 5299 Spring Grove Avenue, Cincinnati OH 45217
Risk assessments typically rely on single species toxicity studies to understand concentrations at which effects may be observed. These single species toxicity studies are usually conducted with only a few species, cultured under optimum conditions (diet, temperature, light, etc.) in clean water with constant exposure to the compound of interest. Results of chronic toxicity studies are then extrapolated to the ecosystem during risk assessments in hopes of establishing concentrations which will not adversely impact the environment. Several approaches have been developed which apply statistical methods to estimate the concentration of test compound adversely affecting a small percentage of single species (e.g., 5%). There are several biological and statistical assumptions required to make these extrapolations which are rarely stated and infrequently tested. One test of the ability to use single species toxicity data to protect an ecosystem is to compare effects on single species with effects on experimental and natural ecosystems (e.g., microcosms, mesocosm, field). Toward this end, we summarized the single species and experimental ecosystem data on a variety of substances (n=11).
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