Constant dosing: reliable exposure concepts to reduce "animal" use

Passive dosing is an approach were the partitioning equilibrium of a substance between a solid and a liquid phase is utilised to maintain exposure concentrations in biotesting. This means that test organisms are exposed at defined and constant concentrations, thus reducing experimental variability and uncertainty, which leads to more robust results.

Together with Philipp Mayer and Kilian E.C. Smith, both formerly of NERI in Roskilde, Denmark, and now with Technical University of Denmark and KIST Europe, respectively, we put out a paper "PAH toxicity at aqueous solubility in the fish embryo test with Danio rerio using passive dosing" in Chemosphere reporting on the usage of PDMS cast into glass vials for passive dosing of non-hatched zebrafish embryos (FET biotest). We show for 10 PAHs constant delivery from the PDMS reservoir to the water phase based on equilibrium partitioning, and prove passive dosing applicable in FET. This test design could in future lead to better data and hence reduced use of zebrafish embryos, albeit legally fish larvae up to 120 hours post fertilization are not considered animals. But we are biologists, we care about any organism.