There's a Huge DDT Dumping Ground in the Ocean Off Los Angeles, and It's Got Scientists Worried

One barrel of thousands found about 10 miles off the coast of Los Angeles. Photo: Screenshot/Valentine’s ROV Jason/CBS Los Angeles

A few years ago, back in 2019, a massive toxic waste dumping ground was discovered off the coast of Los Angeles. It made the news, but didn’t make the quite the splash one would expect. The dumping ground was full of thousands of barrels of Dichlorodiphenyltrichloroethane, which you know as DDT because Dichlorodiphenyltrichloroethane is hard to say.

DDT is a carcinogenic pesticide that was widely used for a few decades between the 1940s and the late 1950s. First used to fight off insect-born diseases like typhus and malaria, it was eventually fond to be very effective for controlling insects in everywhere from farm crops to home gardens. It was a bit of a miracle substance at first – until it wasn’t.

Within a few years, it became apparent that DDT, despite its usefulness, was extraordinarily bad for the environment. Not just the environment, but basically anything it came in contact with. By the late ’50s, the U.S. Department of Agriculture — which was in charge of pesticide regulation before the Environmental Protection Agency (EPA) was created — started cracking down on many of DDT’s uses “because of mounting evidence of the pesticide’s declining benefits and environmental and toxicological effects.”

In 1962, a book called Silent Spring came out. In it, author Rachel Carson wrote about how the chemical industry was impacting the environment. In doing so, she woke the wider world up to the dangers of DDT and just how harmful humankind was being. A decade later, in 1972, the newly formed EPA banned DDT “based on its adverse environmental effects, such as those to wildlife, as well as its potential human health risks.”

DDT has a lot of issues, but the main ones that pertain to us are the facts that it is extremely persistent in the environment, accumulates in fatty tissues, and, if it makes it up to the upper atmosphere, can travel basically all over the world. Although the CDC only considers it a “possible human carcinogen,” everyone’s fairly sure that DDT is super bad for us. “Following exposure to high doses, human symptoms can include vomiting, tremors or shakiness, and seizures,” the CDC wrote. “Laboratory animal studies showed effects on the liver and reproduction.”

All that is to say that a giant DDT graveyard at the bottom of the Pacific off a very trafficked bit of ocean is decidedly bad. Between 1940 and 1960-ish, The Montrose Chemical Corporation of California in Los Angeles simply poured DDT into the sewage pipes feeding into the ocean. After World War II, barrels and barrels of a DDT mixture were hucked off boats, and today they’re still there, rolling around on the sea floor off Catalina Island, leaking away. According to reports, if they floated back to the surface back then, the barrels were simply punctured so they’d disappear.

Everyone kind of forgot they existed until someone noticed that sea lions in the area were dying of cancer at alarming rates. High amounts of DDT were found in their blubber. Then, an ROV poking around down there ran into thousands of barrels 3,000 feet down near Catalina Island, and the connection was made. Since then, researchers have kept a close eye on the DDT dumping ground, and what they’re seeing is… not encouraging.

The most concentrated layer of the stuff is sitting under only about three inches of sand. As is the nature of DDT, it’s not breaking down in any meaningful way, so anyone keeping an eye on it is worried that any disturbance down there could bring it up the surface.

“Trawls, cable lays could reintroduce this stuff back up to the surface,” UC Santa Barbara scientist David Valentine told the LA Times. “And animals feeding — if a whale goes down and burrows on the seafloor, that could kick stuff up.”

No one really has any idea what to do about the stuff and, since it’s sitting around 3,000 feet deep, cleaning it up isn’t an easy task. So for now, the plan is to simply keep a close eye on it and keep all the fingers crossed that it stays where it is.