Abstract: Objective To investigate effects of di(2-ethylhexyl) phthalate(DEHP) plus benzo(a) pyrene(BaP) on Chang liver cells.Methods Chang liver cells were treated with BaP(64 μmol/L) alone or plus DEHP at the concentrations of 0,62.5,125,250,500,and 1 000 μmol/L for 24 hours.The indicators including cell viability,level of intracellular reactive oxygen species(ROS),mitochondrial membrane potential(MMP),apoptosis percentage,and the expressions of Bax,Bcl-2 and activiated caspase-3 proteins were determined.Results Decrease in cell viability in all DEHP and BaP treatment groups and increased ROS generation in all DEHP plus BaP treatment groups were found compared with those of the DEHP treated groups(P<0.05 or P<0.01 for all).The decreases in MMP(80.12±6.41%,69.92±5.56%,and 53.76±1.88%) in the DEHP treatment(≥250 μmol/L) plus BaP treatment(64 μmol/L) groups were observed compared with that of the BaP treatment group(165.93±5.09%,P<0.01).The increases in percentage of apoptotic Chang liver cells in the DEHP plus BaP treatment groups(7.73±1.91%,11.00±3.04%,and 14.20±3.96%) were observed compared with that of the BaP treament group(1.55±0.21%,P<0.01).Furthermore,in the DEHP plus BaP treatment groups,the high active caspase-3 expression and high Bax/Bcl-2 ratio were observed.Conclusion The findings suggest that the co-treatment of DEHP plus BaP induces the reduction of cell viability and the ROS generation and mediate cell apoptosis,which associates with high Bax/Bcl-2 ratio and active caspase-3 expression.