Deep-sixing old warships - win/win, or not ?

For as long as I can remember, the intentional sinking of old ships in the ocean has been presented as eco-friendly (creating "artificial reefs" for fish).  An article at Boston.com summarizes recent concerns that material components within modern ships may be significantly polluting water and contaminating marine life.

Target practice is now how the Navy gets rid of most of its old ships... they wind up at the bottom of the ocean, bringing with them amounts of toxic waste that are only estimated. Navy documents state that among the toxic substances left onboard the America were more than 500 pounds of PCBs or polychlorinated biphenyls, a chemical banned by the U.S. in 1979, in part because it is long-lasting and accumulates throughout the food chain....

The program — called “Sinkex’’ for sinking exercise— has come under fire from environmentalists for the pollutants it introduces to the sea. The ship recycling industry complains about the jobs and revenues it takes away....

“Each vessel is put through a rigorous cleaning process that includes the removal, to the maximum extent practicable, of all materials which may degrade the marine environment,’...

PCB’s found in fish near an aircraft carrier sunk in 2006 as an artificial reef near Pensacola, Florida have raised concerns about the impacts, although the ship was located much closer to shore and in much shallower waters than Sinkex vessels. Annual monitoring by the Florida Fish and Wildlife Conservation Commission of waters around the USS Oriskany concluded that fish around the carrier exceeded state and federal PCB standards in the first two years...

The PCB concentrations in fish have raised public health concerns that require more study to assess the long-term impacts, said Jon Dodrill, an environmental administrator with Florida’s commission. “Our agency has taken a stance that there will be no more large ships with regulated PCBs sunk in state or adjacent federal waters off of Florida,’’ Dodrill said.