In 2018, the OECD published two in vitro OECD TGs — OECD TGs 319A and OECD TG 319B — on the determination of in vitro intrinsic clearance using cryopreserved rainbow trout hepatocytes (RT-HEP) and rainbow trout liver S9 sub-cellular fraction (RT-S9), respectively, serve to improve in silico predictions of chemical bioaccumulation in fish. In vitro intrinsic clearance is determined and used to estimate liver intrinsic clearance, which can be included in physiologically-based toxicokinetic (PBTK) models for fish bioaccumulation assessment. Using an in vitro to in vivo extrapolation (IVIVE) model, in vitro intrinsic clearance can alternatively be extrapolated to an in vivo biotransformation rate constant. The latter can then be included into in silico models for prediction of a bioconcentration factor (BCF).
OECD GD 280 (2018) makes recommendations for performance of TGs 319A and 319B regarding the choice of the test system and includes considerations on test chemicals, applications of in vitro intrinsic clearance and on the predicted BCFs.