QSAR molecular parameters calculated for US EPA ToxCast Phase 1 and 2 chemical compounds tested against embryonic zebrafish

Abstract

Freshwater and marine environments are exposed to small concentrations of many different chemicals produced by industrial, agricultural, pharmaceutical, cosmetic, food, and household applications. Due to concerns regarding potential adverse events from these exposures, regulatory agencies around the world have established aquatic toxicology testing protocols that measure untoward responses in a wide variety of freshwater and marine organisms. Following a literature review of databases on the toxicity of chemicals to fish, the embryonic zebrafish ( Danio rerio) database compiled by the Tanguay Laboratory at Oregon State University was determined to be well suited for quantitative structure–activity relationship (QSAR) analysis. This database possesses a number of favorable characteristics including large size (1060 unique US Environmental Protection Agency ToxCast phase 1 and 2 chemical compounds), relatively recent data collected using state-of-the-art methods, 18 simultaneously measured toxicological end points, transparent embryos that develop externally thereby facilitating toxicological evaluation, and the vast majority of the genetic code is expressed and active during early life stages. The molecular parameters calculated for each of the chemicals in the database include the logarithm of the octanol–water partition coefficient, molar volume, and molar refractivity. For each chemical, the availability of these molecular parameter values can facilitate future QSAR studies using any of the 18 different toxicological end points measured as the biological activity of interest.