Report of the Internal Workshop on Molecular Similarity in Risk Assessment

Abstract

In an attempt to adequately capture the different aspects of molecular similarity, our group thought it would be appropriate to solicit, a variety of opinions regarding chemical similarity and its uses in different situations. While we have some experience and expertise in this field, we felt it important to consider a variety of opinions of internationally known experts about the concept of chemical similarity and its uses. Along those lines, we were fortunate enough to be able to access many researchers and regulators who had intended to participate in the QSAR 92 Conference held in Duluth, MN during July 19-23, 1992. In fact, we felt it essential that we take advantage of the collective body of expertise. To that end, we, in conjunction with United States Environmental Protection Agency (USEPA), sponsored nine key speakers and presenters who, we felt, had broad background in their area of expertise and could share with us their perspectives of what it means for two chemicals to be similar. After selecting our key speakers, we. arranged for many of them to be present at QSAR 92. During the course of the conference, we made arrangements to meet and have open discussions regrading chemical similarity with these speakers. The participants were questioned about what they thought were the critical elements or processes relevant to their subject area and the relevancy or uses of chemical similarity in their field of expertise. Many of these participants provided papers, which were reviewed for content relevant to chemical similarity and are provided in Appendix A. The goal of this exercise was to distill the common elements critical to operationalizing a method or system of components to formulate, implement, test, and validate chemical similarity models. This would lead to the development of a computer system design that incorporates many of the essential elements together under a common interface. We felt that it was essential that regulatory, toxicological, and computational perspectives of chemical similarity be taken into account during the course of this project. The remainder of this report will detail these different perspectives, and then discuss and review the common features to be used, with the hope that this will facilitate a computer software system design to accomplish the objectives of this project.