QSAR for Reactive Toxicity Advances Our partnership with the University of Tennessee College of Veterinary Medicine is making last minute arrangements for the 2nd Knoxville Workshop on Reactive Toxicity to held April 1-4, 2006. Reactive toxicity are toxic effects caused by chemicals which irreversibly bind to lipids, proteins and DNA…effects which have been some of the most difficult to predict by toxicologists without extensive animal testing. The annual Knoxville retreat invites international experts to discussion predictive models for some of the more costly animal tests such as skin sensitization, chronic toxicity, inhalation toxicity and toxicity to fish. The 1st Knoxville workshop in 2005 accomplished a major IQF goal by formulating a conceptual framework for predicting reactive toxicity. At the heart of the conceptual framework is the use of model compounds which simulate natural proteins and other important cellular targets for reactive chemicals and produce a reactivity profile. These model compounds are easily synthesized and react with chemicals in a test tube, so measuring chemical reactivity does not have to involve any animals or cells. The 2nd Knoxville Workshop will review the progress made over the last year to use the reactivity profiles for predicting skin sensitization, sensory irritation and other regulatory effect endpoints. A team of immunologists will be discussing heptenation and methods for modeling the selectivity of the immune system for protein-bound complexes. Recent data on sensory irritation in animal inhalation tests involving fragrances and other volatile chemicals were found to contain many errors. The 2nd Knoxville Workshop is expected to report more reliable models based on the use of the high quality databases being compiled by IQF.