The disposal of sewage at sea has a greater effect on the deep-sea food chain than was previously believed, U.S. researchers said today.
The massive dumping of sewage sludge at a site off the New Jersey coast has contaminated marine animals at a depth of 8,600 feet, they reported.
In a report published in the British scientific journal Nature, Dr. Cindy Lee Van Dover at the Woods Hole Oceanographic Institution in Massachusetts and her colleagues say "megascale" pollution of the sea 115 miles off the coast of New Jersey has occurred.
"Until now it had been assumed by many environmental officials that sewage sludge dumped in the ocean would be diluted and not even reach the ocean bottom," said Ms. Van Dover, a co-author of the report.
"Our study shows that it does reach the ocean floor and that sea animals are taking it into their bodies and becoming contaminated," she said. "In hindsight this may seem obvious. But the findings will come as a surprise to many."
The findings are based on a research expedition carried out at the dump site in July 1991 by Woods Hole, the University of Maryland, Rutgers University, Columbia University and other institutions.
Ms. Van Dover said there was no evidence that commercial species of fish had been contaminated by the sludge dumping.
But because fish eat the kinds of marine animals that have become polluted and then other fish eat those fish, the findings raise concerns about how high in the food chain the contamination might go.
Fred Grassle, an ecologist at Rutgers and one of the co-authors of the report, said the findings raise questions about whether other man-made chemicals may have entered the ocean's food chain, as well.
"Sludge contains traces of pesticides, heavy metals, PCBs, organic chemicals and human pathogens," he said. "You name it -- it probably can be found in sludge."