Effect of Pre-exposure to Treated Wastewater Effluent on in vitro Biotransformation Rates of Hydrophobic Chemicals in Rainbow Trout (Oncorhynchus mykiss)

Efforts have been made to develop extrapolation methods of in vitro biotransformation data to improve chemical bioaccumulation assessment. A criticism of these methods is that animals used for in vitro studies may not represent animals in environments where contaminants are present. The effect of municipal wastewater effluent exposure on biotransformation rates of benzo(a)pyrene, pyrene, chrysene, and 9-methylanthracene in a rainbow trout liver preparation was examined. Results were extrapolated to organism level and modeled bioconcentration factors (BCFs). In vitro biotransformation rates (kr) for benzo(a)pyrene and pyrene were elevated in one experiment following exposure to 10% effluent and when extrapolated, respective BCFs decreased. In a second experiment, exposure to 20% effluent had no significant effect on the mean kr values for the test chemicals. Variability of kr between exposures could be attributed to differences in effluent composition between experiments. This research highlights the importance of considering environmental factors in chemical bioaccumulation assessment.