Use of QSAR models in predicting joint effects in multi-component mixtures of organic chemicals

The application of Quantitative Structure Activity Relationship (QSAR) models in predicting joint toxicity of mixtures of organic chemicals to microorganisms is presented. In the proposed approach, QSAR models derived from single chemical toxicity assays are used to predict concentrations of components in mixtures that would jointly cause 50% inhibition of microbial respiration. Experimental joint toxicity data from several different binary and multi-component, uniform and non-uniform mixture assays on two microbial cultures are used to validate the proposed approach. The predictions made from QSAR models agreed well with the experimental data with r2=0.80 at p=0.0001 for a total of 610 data points. The factor of error of the predictions ranged from 1.00 to 4.79, averaging 1.82. Validation tests with 16 chemicals not used in the QSAR model derivation yielded predictions of similar quality.