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(25-02) Comparison of predicted environmental toxicity derived from ECOSAR with experimental data for various organosilicon-based materials. Powell, D.1, Ransom, R.1, Stevens, C.*,2, 1 Dow Corning Corp., Midland, USA2 Dow Corning Corp., Seneffe, Belgium ABSTRACT- A possible consequence of the pending EU Chemicals Policy may be the need to conduct risk assessments on thousands of chemicals. It is anticipated that there will be increased emphasis on the use of structure activity relationship (SAR) models to identify chemicals of potential environmental concern. Many of these models, such as ECOSAR (Ecological Structure Activity Relationships), developed by the United States Environmental Protection Agency, are based upon SAR correlations between Log octanol/water partition coefficient (Log Kow) and measured toxicity to aquatic organisms for individual chemical classes. ECOSAR is a program that provides access to over 100 SAR models developed for 42 chemical classes. The SAR models are used to estimate the toxicity (acute and chronic) of individual chemicals to freshwater and marine organisms, including fish, invertebrates and algae. As a general rule, SAR models provide a reasonable estimate for chemical classes or families for which the SAR was developed. However, the error associated with SAR-estimated toxicity values for individual compounds may range from 1-2 orders of magnitude or greater for chemicals of low water solubility. For these chemicals, Log Kow values approach the boundary conditions for the model. This presentation will use output from ECOSAR to discuss the appropriateness of using SAR models for estimating potential aquatic toxicity for a range of organosilicon-based materials. Key words: organosilicon, aquatic toxicity, SAR, physico-chemical properties |
