Fig. 1.
PCB 91, PCB 95, PCB 132, and PCB 136 were primarily present in the cell culture medium from experiments (a) with or (b) without HepG2 cells. Only a small percentage of the PCBs were recovered from the cell pellet (8.0 to 14.6 %) or the cell culture dish (2.3 to 7.8% for cell culture group and 3.7 to 7.2% for cell-free group). HepG2 cells (6×106/well) were seeded into 6-well plates with complete MEM medium (3 mL) per well and allowed to attach for 48 h. Cells were exposed for 72 h to the individual PCB congeners (0.25 μM; 0.1 % DMSO) in exposure medium (3 mL) with 10 % FBS. Controls were exposed to 0.1% DMSO in the exposure medium. Parallel incubations were performed for cell-free groups. After the incubation, the media, cell pellets, and cell culture dishes were collected, and PCB levels were determined as described in the Experimental Section.