Combined risk assessment of organic pollutants (PCBs and OPEs) accumulation in Rice (Oryza sativa L.)

Combination risk of polychlorinated biphenyls (PCBs) and organophosphate esters (OPEs) contamination to the accumulation and tolerance mechanism of plants were investigated under a series of designed hydroponic experiments. The combined organic pollutants could more significantly promote plant growth than all of single organic pollutants. The positive role of pollutants in growth could be attributed to hormesis effect according to the transcript response of hormone genes. OPEs were more liable to be accumulated than PCB18 in rice. In opposite hydrophilicity (PCB18 and TCEP) pollutants combination, the accumulations of the total pollutants and TCEP in seedlings were obviously promoted compared with the single pollutant treatments. However, in similar hydrophilicity pollutants (PCB18 and TPHP) combination, TPHP and total organic pollutant accumulations in rice were inhibited. It was worthy notice that the accumulations of PCB18 in shoots were significantly increased under the combined treatments. Transcript and bioinformation analysis of lipocalins demonstrated that their interaction with OPEs were higher than PCB18, and OsTIL could directly take part in uptake, translocation and accumulation of OPEs rather than PCB18. Tolerance mechanism in rice included antioxidative enzymes and lipocalins cooperatively resisted pollutants’ oxidative stress. Therefore, the combined organic pollutants could induce high risk to food safety according this study.