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Intra- and inter-laboratory reliability of a cryopreserved trout hepatocyte assay for the prediction of chemical bioaccumulation potential
Citation:
Fay, K., R. Mingoia, I. Goeritz, D. Nabb, A. Hoffman, B. Ferrell, H. Peterson, J. Nichols, H. Segner, AND X. Han. Intra- and inter-laboratory reliability of a cryopreserved trout hepatocyte assay for the prediction of chemical bioaccumulation potential. ENVIRONMENTAL SCIENCE AND TECHNOLOGY. John Wiley & Sons, Ltd., Indianapolis, IN, 48(14):8170-8178, (2014).
Impact/Purpose:
In our paper, three laboratories measured in vitro intrinsic clearance rates for six test compounds. Reliability was evaluated by characterizing intra- and inter-laboratory variability in measured levels of activity as well as parameters (cell yield and viability) related to assay performance. Measured levels of clearance were then used as inputs to a computational model for chemical bioconcentration to examine how variability in measured in vitro clearance contributes to variability in predicted levels of accumulation (e.g., steady-state BCFs). Finally, predicted BCFs were compared to empirical values to illustrate the relevance of these procedures. The results of this study provide strong support for use of these methods as part of a tiered approach to bioaccumulation assessment.
Description:
Cryopreserved trout hepatocytes provide a convenient in vitro system for measuring the intrinsic clearance of xenobiotics. Measured clearance rates can then be extrapolated to the whole animal as a means of improving modeled bioaccumulation predictions. To date, however, the intra- and inter-laboratory reliability of this procedure has not been determined. In the present study, three laboratories determined in vitro intrinsic clearance rates for six reference compounds (benzo[a]pyrene, 4-nonylphenol, di-tert butyl phenol, fenthion, methoxychlor and o-terphenyl) by conducting substrate depletion experiments with cryopreserved trout hepatocytes from a single source. O-terphenyl was excluded from the final analysis due to non-first-order depletion kinetics and significant loss from denatured controls. For the other five compounds, intra-laboratory variability (% CV) in measured intrinsic clearance values ranged from 4.1 to 30%, while inter-laboratory variability ranged from 27 to 61%. Bioconcentration factors calculated using measured clearance values exhibited a lower level of inter-laboratory variability (5.3 to 38% CV). The results of this study demonstrate that cryopreserved trout hepatocytes can be used to reliably obtain biotransformation information for fish, and provide strong support for the application of this in vitro method as part of a tiered approach to chemical bioaccumulation assessment.
