title: Improving the reliability of aquatic toxicity testing of hydrophobic chemicals via equilibrium passive dosing - A multiple trophic level case study on bromochlorophene.
abstract: The main objective of the present study was to improve the reliability and practicability of aquatic toxicity testing of hydrophobic chemicals based upon the model substance bromochlorophene (BCP). Therefore, we adapted a passive dosing format to test the toxicity of BCP at different concentrations and in multiple test systems with aquatic organisms of various trophic levels. At the same time, the method allowed for the accurate determination of exposure concentrations (i.e., in the presence of exposed organisms; Ctest) and freely dissolved concentrations (i.e., without organisms present; Cfree) of BCP in all tested media. We report on the joint adaptation of three ecotoxicity tests - algal growth inhibition, Daphnia magna immobilization, and fish-embryo toxicity - to a silicone O-ring based equilibrium passive dosing format. Effect concentrations derived by passive dosing methods were compared with corresponding effect concentrations derived by standard co-solvent setups. The passive dosing format led to EC50-values in the lower μgL-1range for algae, daphnids, and fish embryos, whereas increased effect concentrations were measured in the co-solvent setups for algae and daphnids. This effect once more shows that passive dosing might offer advantages over standard methods like co-solvent setups when it comes to a reliable risk assessment of hydrophobic substances. The presented passive dosing setup offers a facilitated, practical, and repeatable way to test hydrophobic chemicals on their toxicity to aquatic organisms, and is an ideal basis for the detailed investigation of this important group of chemicals.
authors.affiliation: Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany. Electronic address: felix.stibany@rwth-aachen.de.
authors.forename: Felix
authors.initials: F
authors.lastname: Stibany
authors.affiliation: Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Ewald
authors.affiliation: Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Ina
authors.initials: I
authors.lastname: Miller
authors.affiliation: Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Henner
authors.initials: H
authors.lastname: Hollert
authors.affiliation: Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schäffer
mesh_terms: D000818:Animals; D002733:Chlorophenols / Q000633:toxicity*; D000460:Chlorophyta; D003621:Daphnia; D004625:Embryo, Nonmammalian; D057927:Hydrophobic and Hydrophilic Interactions; D015203:Reproducibility of Results; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish / Q000196:embryology
chemical_list: D002733:Chlorophenols; D014874:Water Pollutants, Chemical; C013422:bromochlorophen
keywords: Algae; Bromochlorophene; Danio rerio; Daphnia magna; Freely dissolved concentration; Passive dosing