That was looked at in some detail by the northern river basins study, which saw no evidence. The problem has been that the big development in the oil sands has occurred since the northern river basins study took place. At that time, there were only two rather sleepy little oil sands plants in operation. The huge development we see today really started rolling about 2003.
There is now some debate over whether polycyclic aromatics and mercury deposited in the sediments near the river's mouth and the lake are increasing. Again, I think the regional aquatics monitoring program has some data. I haven't seen the results of independent studies, which have largely been done in the last year or so, but it is a matter of some debate at the present time.