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A new study from the Scripps Institution of Oceanography examines dangerous pesticides that have spread over the years.
SAN DIEGO — The federal government banned the use of DDT in the early 1970s, but more than 50 years later, researchers are still finding fish off the coast of Southern California that have the dangerous pesticide in their bodies.
“No one would have believed the problem would persist for this long,” said Lillian McGill, who led the research team at the Scripps Institution of Oceanography. Her team has been investigating the long-term effects of DDT on the fish we eat.
From 1940 to 1970, the company that manufactured DDT dumped hundreds of tons of contaminated waste into the ocean at several locations, including one off the coast of San Diego. A video taken several years later shows the giant barrel sitting on the ocean floor.
“There are certainly DDT hotspots throughout Southern California where you have to be very careful about what you eat,” McGill said.
She added that a surprising finding in their study was that DDT didn’t actually spread very far from where it was dumped. However, the sediments at those locations were definitely contaminated.
“Our results show that species that live in sediments much lower in the water column, like halibut, tend to have much higher concentrations of DDT.”
But McGill said the fish caught off the coast of San Diego showed no signs of dangerous contamination. That’s because the dumping in our area occurred much further away, in deeper waters. The same can’t be said for fish in the Palos Verdes Peninsula area of Los Angeles County, where dumping occurs just off the shoreline.
“We were really surprised to see such a strong relationship between fish and sediment contamination,” McGill said. “If you look at this, there’s a pretty linear relationship: higher DDT in the sediment, higher DDT in the fish.”
The researchers also found that DDT concentrations in fish today are not as high as they were in the late 1990s, but are they wondering if the water has become safer or if contaminated sediment has been buried by new sediment over time? is not clear.
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