For decades, an unknown number of barrels of hazardous chemicals have sat on the ocean's floor just miles off the Palos Verdes Peninsula, worrying scientists and environmentalists.

But now, a team of researchers -- led by scientists from UC San Diego’s Scripps Institution of Oceanography and the National Oceanic and Atmospheric Administration -- have concluded a nearly two-week study to determine the extent of environmental damage and, potentially, who might be to blame.

The study, which concluded Wednesday, March 24, included verifying how many barrels sit at the bottom of the ocean containing the toxic chemical DDT, said NOAA spokesman David Hall.

The researchers used two autonomous underwater vehicles to conduct a sonar scan of the sea floor, said Lauren Wood, director of strategic communications at Scripps. Their goal was to detect debris they can identify as barrels in a larger area of the sea floor than previously possible.

“They may not necessarily be able to say what's in those barrels," Wood said, "but they'll be able to see what is on the sea floor."

This was not the first time scientists have explored the Palos Verdes Shelf and areas off the coast of Catalina Island. A group of scientists discovered what potentially could be hundreds of thousands of barrels, some still intact, some leaking with what scientists call “toxic icicles” hanging off the sides. In 2011, UC Santa Barbara scientists and other collaborators discovered barrels of industrial waste, many decaying, on the ocean floor.

The main culprit, scientists say, is likely DDT, a synthetic insecticide developed in the 1940s and banned in 1972 for its detrimental impacts on humans and wildlife. The now-defunct company Montrose Chemical Corporation manufactured, packaged and distributed DDT from 1947 to 1982 at 20201 Normandie Ave. The company reportedly dumped the pesticide into the ocean for decades, some of it reaching the 17-mile Palos Verdes Shelf.

The U.S. Environmental Protection Agency identified the area as a Superfund site in 1989, meaning it’s one of the nation’s most toxic collections of pollution.

In 2001, state and federal agencies reached a $140 million settlement with Montrose, which included paying for a restoration project.

And although the barrels that are currently being surveyed are unrelated to the $140 million settlement, scientists have not yet officially determined if they, too, may have belonged to Montrose.

Discovering the barrels

David Valentine, professor of microbiology and geochemistry at UC Santa Barbara, said in the early 2000s he came across a dusty report that had been sitting on the shelf for decades that said there could be upwards of 500,000 barrels of toxic substances.

Allan Chartrand, who was at the time a regulatory scientist of the California Regional Water Quality Control Board, conducted that study. He was able to get access to Montrose company records, Valentine said, but nothing came from that report.

But Valentine said he was intrigued.

So in 2011 and 2013, he and fellow scientists used a remotely operated vehicle and discovered around 60 to 100 barrels in a small survey area about 3,000 feet below the surface, he said in a phone interview last week.

Those barrels, in an area with limited visibility, were in various states of disrepair, Valentine said. Some were intact, he said, but others had ruptured and spilled. Still others were embedded in the sea floor, possibly concealing damage.

“Some of them had unusual growths coming off of them that looked like stalactites," Valentine said. "We call them 'toxicles' because they had that sort of appearance."

And the samples of the material they took, Valentine said, had extremely high concentrations of DDT, with some also containing petroleum-derived compounds.

In 2012, Valentine said, he “started banging the drum” on the findings and after the 2013 expedition, he spent the next several years “trying to get people interested” in their findings.

Valentine said he did public talks and posted footage of what they found online. He approached local U.S. Congress members and federal agencies, and went to Washington, D.C., to talk with staff for the House Committee on Energy and Environment.

But it was not until they published the first paper describing the site and other aspects of their reconnaissance mission in 2019, followed by an investigative story in October 2020 in the Los Angeles Times, that people started to take notice.

Since then, Valentine said, he has been working with the scientific team that is leading the survey currently underway.

“We don’t assume that any of the barrels," Valentine said, "are from any particular company.

“The assumption of material dumped from Montrose Chemical Company comes from samples of sediment that were collected in the vicinity of the barrels,” Valentine added. “Some of those sediment samples had basically smoking-high levels of DDT in them.”

The peak sample, Valentine said, had 40 times the highest concentration of DDT surface sediment contamination found on the Palos Verdes Shelf.

The DDT and related products, he said, were part of a mixture that were apparently petroleum derived compounds from the industrial distillation process.

“That’s what the chemistry is telling us,” he said.

Research continues

The current study, the results of which won't be released for a few weeks, stems from Valentine's study, continuing the years-long work to determine the environmental damage off California's coast -- and ultimately fix the problem.

The Palos Verdes Shelf was added as a Superfund site in 1989.

The Palos Verdes Reef Restoration Project was completed last year as part of the $140 million Montrose settlement. An artificial reef was designed to attract fish and other marine animals, while creating fishing opportunities, decimated by reef loss and contamination from DDT and other chemicals

But not counted in the creation of the Superfund site, according to Valentine's 2019 study, was the ocean disposal of an estimated 2,000 to 3,000 barrels per month, from around 1947 to 1961, equaling 1 million gallons of waste per year.

The Scripps and NOAA survey will map the ocean floor to help determine the extent of the damage that remains. Officials, who urged the study, touted the work.

Rep. Nanette Barragan said her team is working closely with Rep. Alan Lowenthal, other local offices and federal agencies.

“It’s good news that an underwater mapping project has finally started at the dump site,” U.S. Rep. Nanette Barragan, D-San Pedro, said in an email. “The information it provides will be valuable in  guiding our next steps in addressing this issue.”

The study also comes as elected officials in Washington continue pushing the federal government to ensure the area gets cleaned up.

U.S. Senator Dianne Feinstein, for example, wrote a letter earlier this month to acting EPA  Administrator Jane Nishida, in which she called DDT pollution a serious threat to wildlife and human health, because it “has been linked to increased cancer rates among California sea lions and is a known cancer risk to humans.

“After two decades of studies and monitoring, the Palos Verdes Shelf clean-up is still to complete,” Feinstein wrote. “I know this is a complex undertaking, however I am dismayed at the slow progress despite tens of millions of dollars spent on the cleanup over the last two decades.”

Local officials have also advocated to have the barrels cleaned up.

"We wanted to apply some advocacy and public pressure to all the agencies," Rancho Palos Verdes Mayor Eric Alegria said, "because clearly this is an issue in need of multi-agency coordination and support."

Editor's note: The now-defunct Montrose Chemical Corporation manufactured, packaged and distributed DDT in an unincorporated area of Los Angeles County near Torrance from 1947 to 1982. Because of a reporting error, the company's location was incorrect in a previous version of this story.

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