Hard question! I think many experimental studies are requested to find the answer. Selenium is the cofactor of antioxidative enzymes and the turn over of that enzyme can be a determinant. The amount of Se is dependent to amount of ROS level of your culture. I suggest to modeling this impressive question.
I agree with Isaac, quite a lot of experimental work is required to solve your question. Furthermore, it will depend on the cell type, environmental conditions, etc. Maybe the article in the attachment can give you some hints where to start.
Cheers, Christian
Article Antioxidants activities and concentration of selenium, zinc ...
Isaac is spot on. The amount of Se is dependent on the ROS level of in the culture. I also think to modeling this question.lol. A lot of investigation is needed to solve this.