I have no doubt that there was a lot of this sort of contamination around long before the BP oil spill, but the BP oil spill will send this contamination to a whole new level.
Ther was also a lot of contamination of seafood from this area already, (which gives a good indication of how long toxic substances can remain in the environmental eco system), and again, I suspect that this will reach a whole new level, with the effects from this oil spill, and the use of dispersants.
As more and more of the oil rigs in the Gulf, come to the end of their working lives, and without tightening of the safety regulations for new drilling platforms, there will be more and more disasters such as the BP spill.