title: Intrinsic Clearance of Xenobiotic Chemicals by Liver Microsomes: Assessment of Trophic Magnification Potentials.
abstract: The use of trophic magnification factors (TMFs) to characterize the bioaccumulation potentials of chemicals was encouraged; however, the method for the assessment of trophic magnification potentials is still lacking. We optimized the in vitro assays used for the measurement of intrinsic clearance in liver microsomes by incorporating benzo[a]pyrene (B(a)P) as a benchmark compound. The intrinsic clearance of 40 compounds was then measured in microsomes from fish (weevers) and birds (quail); the characteristics of the trophic transfer of these 40 compounds were previously investigated in an aquatic food web in Bohai in northern China. Chemicals that are biotransformed at a rate similar to or higher than that of B[a]P in the microsomes of both weevers and quail (in vitro intrinsic clearance values, CL; CL/CLB[a]P: 0.1 to 2.4) generally exhibited no significant trophic magnification or dilution in the food web (TMF ≈ 1 or < 1), whereas chemicals that are biotransformed at extremely slow rates compared with B[a]P (CL/CLB[a]P: 0 to 0.2) showed significant trophic magnification in the food web (TMF > 1). The in vitro intrinsic clearance values of the target chemicals were found to be consistent with their respective trophic transfer behavior in the aquatic food web. Significant negative correlations were also found between the TMFs and the intrinsic clearance values of all target chemicals obtained in microsomes from both weevers and quail. Multiple linear regression analysis showed that biotransformation rates (CL/CLB[a]P) are a more important factor compared with the lipophilicity of the chemicals (log Kow) in the assessment of the trophic magnification of chemicals in the aquatic food web.
authors.affiliation: Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University , Beijing 100871, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Guomao
authors.affiliation: Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University , Beijing 100871, China.
authors.forename: Wan
authors.initials: W
authors.lastname: Yi
authors.affiliation: Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University , Beijing 100871, China.
authors.forename: Hu
authors.initials: H
authors.lastname: Jianying
mesh_terms: D000818:Animals; D005399:Fishes / Q000378:metabolism; D020387:Food Chain; D007700:Kinetics; D008862:Microsomes, Liver / Q000378:metabolism*; D014874:Water Pollutants, Chemical
chemical_list: D014874:Water Pollutants, Chemical