DDT Dumped Decades Ago Off LA Coast Is Still Potent

Broad effort tries to assess the Pacific Ocean contamination introduced decades ago
By Bob Cronin,  Newser Staff
Posted Mar 24, 2023 5:05 PM CDT
DDT Dumped Decades Ago Off LA Coast Is Still Potent
Catalina Island, off the Los Angeles coast.   (Getty / OrlowskiDesigns)

Research revealed this week confirmed some scientists' worst fears about the dumping of barrels of DDT off the California coast in the 1940s and '50s: Much of the banned toxic chemical remains in its most potent form. "We still see original DDT on the seafloor from 50, 60, 70 years ago, which tells us that it's not breaking down the way that [we] once thought it should," said David Valentine, a scientist who updated colleagues on Thursday, the Los Angeles Times reports. "And what we're seeing now is that there is DDT that has ended up all over the place."

Valentine and his University of California, Santa Barbara, team have been taking samples from the Pacific seafloor between Catalina Island and the Los Angeles coast. The results show the most concentrated layer of DDT is about 6 centimeters deep. "Trawls, cable lays could reintroduce this stuff back up to the surface," he said. "And animals feeding—if a whale goes down and burrows on the seafloor, that could kick stuff up." DDT has shown up in an area larger than San Francisco. Federal, state, and local agencies are working with scientists and environmental nonprofits to assess the multifaceted problem.

Next, an expedition will use advanced sonar technology to scan the ocean floor, taking hundreds of thousands of photos. Microbiologists are studying whether deep-sea microbes could help biodegrade the pesticide. The Environmental Protection Agency is drawing up its own sampling effort to learn what other chemicals have been dumped into the water and whether the contamination is moving. There are implications of the contamination for public health, as well as for future use of the Pacific. "We're still grappling with this legacy of treating the ocean as a dumping ground," said Katherine Pease of the environmental group Heal the Bay. (More DDT stories.)

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