Application of thin-film solid-phase dosing to measure in vitro biotransformation rates of organic chemicals in rainbow trout (Oncorhynchus mykiss)

Methods for assessing the bioaccumulative potential of chemicals have been criticized for their inability to consider biotransformation in living organisms. This current study developed and tested an in vitro method, using liver S9 liver homogenates to determine biotransformation rates of very hydrophobic xenobiotics in rainbow trout (Oncorhynchus mykiss). The study compares two biotransformation assays, i.e. the solvent delivery method and a novel thin-film solid-phase dosing system. Biotransformation rate constants of benzo[a]pyrene (0.9087 min-1; logKow 6.04), chrysene (0.0796 min-1; logKow: 5.81), and 9-methylanthracene (0.0011 min-1; logKow: 5.07) determined by solid phase dosing were 44, 17, and 0.8-times higher than those measured using the solvent delivery method. The results suggest that the EVA dosing is a useful alternative to the solvent delivery method especially for chemicals of extreme hydrophobicity and for chemicals that are difficult to dissolve in aqueous media.