Yolk–Water Partitioning of Neutral Organic Compounds in the Model Organism Danio rerio

Abstract Yolk is the most important temporary biological compartment of the early life stages of fish embryos. The sorption strength of a chemical to yolk components may significantly influence the distribution of that chemical in the fish embryo. We determined yolk–water partition coefficients (Kyolk/water, in liters of water per kilogram of yolk, normalized to dry wt) for 70 neutral organic chemicals. The log Kyolk/water values range from 0.76 to 6.56. On the basis of these values, we developed polyparameter linear free energy relationship models to predict yolk–water partitioning for a broad range of neutral organic chemicals with a root mean squared error of 0.37 and r2 of 0.919. These models can be applied for the prediction of internal concentrations at equilibrium (neglecting biotransformation and active transport) in the zebrafish embryo test system. Environ Toxicol Chem 2020;39:1506–1516. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Abstract Distribution of chemicals between yolk and water.