500,000 barrels of DDT in the sea: Interview with documentary directors on California coast crisis

Half a million barrels of toxic waste lurking beneath the waves just miles from California’s coastline sounds like the plot of a Hollywood thriller. Yet this environmental catastrophe is real, as documented in the award-winning film Out of Plain Sight, co-directed by journalist Rosanna Xia and filmmaker Daniel Straub.

The documentary follows Xia, a Pulitzer Prize finalist and coastal reporter for the Los Angeles Times, as she investigates a haunting discovery made by University of California, Santa Barbara, professor David Valentine. During a routine research expedition, Valentine’s underwater robot captured images of corroded barrels scattered across the seafloor near Catalina Island — remnants of a massive toxic dumping operation dating back to the post-World War II era.

Rather than presenting a retrospective account of events, the film unfolds in real time. Viewers experience each revelation alongside Xia as she connect the dots between Valentine’s discovery, historical records, and the ongoing health and environmental consequences of the once widely used insecticide DDT (dichlorodiphenyltrichloroethane).

The documentary illustrates how DDT, although banned in the U.S. in the 1970s, continues to impact marine ecosystems and human health today. “DDT is the original ‘forever chemical’ before that term even existed,” Xia told Mongabay.

Xia’s reporting carries the torch of Rachel Carson, whose 1962 book Silent Spring first drew public attention to the dangers of DDT. “Rereading Silent Spring decades later and seeing how these messages are still concerns and themes we’re living with today was striking,” Xia said.

“The public would not know about this story in the way that we do without Rosanna’s reporting,” Straub told Mongabay. Since Xia first reported the story, the state of California and U.S. Congress have allocated more than $16 million to study DDT.

Out of Plain Sight takes an immersive visual and acoustic journey through coastal ecosystems, research vessels and laboratories that brings viewers directly into the scientific process.

The film “dramatically illustrates both the importance and process of science and journalism, at a time when both are under attack,” Andy Howell, a staff scientist at Las Cumbres Observatory and a professor at UCSB, said in a review of the documentary for Film Threat.

Straub, a director with more than a decade of experience in documentary filmmaking, brings a cinematic eye to this environmental investigation. The film’s visuals of redwood forests, ocean vistas and coastal landscapes aren’t merely aesthetic choices. They establish the high stakes of what we stand to lose through environmental neglect.

“This is a tragic story, but it’s tragic because the environment where the story takes place is so beautiful,” Straub said. “Being able to show these redwood forests, the ocean, or the cliffs near Big Sur, and present them as beautiful places was important to understand the stakes: this is what we stand to lose.”

The film will be screened in Washington, D.C., on March 29 at the 2025 DC Environmental Film Festival, where Mongabay is a media partner.

Mongabay’s Liz Kimbrough interviewed Xia and Straub about why and how they made Out of Plain Sight and the impact they hope the film will have. This interview has been edited for length and clarity.

Mongabay: Let’s start at the beginning. Rosanna, you broke this story in 2020. When and how did you first learn about the barrels of DDT found off the California coast?

Rosanna Xia: Professor David Valentine, a beloved professor at UC Santa Barbara, had come across these barrels on an expedition a couple years prior to reaching out to me. He had access to an incredible research vessel and deep-sea technology from Woods Hole Oceanographic Institution. They were studying something completely different but had a contingency day and extra time. Good scientists block in contingency days for research expeditions. He had a hunch after seeing a latitude and longitude written in an old document years ago and dropped the underwater robot just a couple miles offshore from Los Angeles. He came across these barrels and thought, “Oh my God, what are these?”

He did a lot of due diligence, making numerous phone calls. I was honestly his last call when no one else engaged with what he was finding. I’m the coastal ocean reporter at the Los Angeles Times, and it’s wonderful to have a newsroom large enough for specialized environmental reporters. He had been reading my work and reached out to me.

I reread Rachel Carson, dug up shipping logs, and one of the most haunting things about the story is that all of it was in the public record. It wasn’t something done secretly — it was a period of our history that this was acceptable at the time. We didn’t know any better, and then we collectively forgot about it.

Mongabay: When did you decide to create a documentary? How did that happen? And Daniel, when did you come on board?

Rosanna Xia: When that first article came out, many people emailed me saying this needs to be a film. I received numerous ideas and was honestly overwhelmed. As a pretty old-school journalist, I was really nervous because this is a complicated story with a lot of messiness. Getting the science right is hard enough in a written article — I was concerned about what that would look like in a film. This story didn’t need to be sensationalized.

The LA Times studio team helped me go through many of the initial queries. Then Daniel and his brother Austin Straub, who was the amazing cinematographer and film editor on this project, showed up to one of my talks. They didn’t dictate what the film needed to be or what the ending should be. They just asked, “Can we join you the next time you’re in the field with a camera?” In that moment, I knew these were the right people. I felt in my gut that they respected the journalism, honored the science, and while they didn’t know exactly what the story was, they wanted to be there to discover it together.

Daniel Straub: Austin read that first story when it was published and showed it to me, saying “this is a crazy story.” We discussed it and thought it would be cool to make a documentary about it someday.

We reached out to Rosanna, ambushed her at one of her book talks, and asked if we could try to film something and tag along with her in the field. Shortly after that, we were on a boat with Rosanna and David Valentine, mapping out what would become a film. At the time, we were just excited to document the process.

What was unique about the language of the film is that it wasn’t retrospective — it was us following Rosanna as she followed the story. That allowed the film to feel like an extension of Rosanna’s reporting rather than just a repackaging of it.

From the first day, before we even knew what we were making, I could tell that Rosanna was the right person to tell this story, both on camera and guiding the film. I suggested that we direct it together, and she agreed. We convinced her over the course of filming that the audience has a reason to be there because of her — she is the stand-in for every viewer. She became that proxy for the audience, both in terms of why they would be in these spaces and the questions they would be asking. That unique aspect allows us to demystify the process of journalism. It’s not just this mysterious process of “I went and talked to a bunch of people and poof, there’s an article.” We’re really seeing those questions being worked through in real time.

Rosanna Xia: To build on that: the first article came out, and I continued to write many more articles because there was impact from that initial piece. There was a lot of science mobilized and interest from Congress to support it. Once we enabled different research institutions, an entire community of marine scientists and ecotoxicologists came together to help piece together parts of a puzzle we didn’t even realize existed. When people went out to look, with the resources to do so, we kept finding more things, and there were many more layers and twists to the story.

That first article and that first barrel David Valentine found underwater were just the tip of the iceberg to a much bigger story. Daniel and Austin recognized in the field that this wouldn’t be a retrospective story where we talked about events in past tense with me explaining what happened. Emotionally, it’s fascinating that Daniel and Austin were present as more developments unfolded, and we present this film in the present tense.

Mongabay: One of the things that was so compelling was that journalism itself is a main character. As a journalist, watching this process was fascinating. Why did you make this decision?

Daniel Straub: We didn’t grow up hearing about DDT or reading Silent Spring. The first time we’d heard about DDT, other than passing references, was when we read Rosanna’s story. So allowing Rosanna to be not only our proxy in the field but our proxy through history was important. This isn’t just a 12-minute catch-up on the history of DDT — it’s also the work Rosanna had to do to piece together this history for the audience.

That became a guiding principle once we realized this is the story of Rosanna following the story. We asked how to cover the history with that perspective. One of the first things Rosanna said she did when she heard about the story from Dave was crack open Silent Spring and catch up on the history of the issue. We wanted the audience to have that same experience.

At the beginning of the project, Rosanna shared with us the quote from Rachel Carson: “The obligation to endure gives us the right to know,” and that was a guiding principle for the story.

Rosanna Xia: The audience was learning everything the way I was learning it. In that way, there was an emotional space that felt grounding despite how intense and horrifying this issue is.

Mongabay: In the film, you ask, “Is this an unknown chapter of history or forgotten?” And you reveal that this wasn’t a big secret conspiracy. A lot of this dumping was legal.

Rosanna Xia: We did treat the ocean like the world’s biggest landfill. Going back through history, there was all this toxic waste that we felt uncomfortable putting in a landfill because it felt too close to home. So we dumped it into the ocean, thinking we could forget about it once it was out of sight, out of mind.

Decades later, generations later, we’re starting to piece together how what we put in the ocean is ultimately connected to all of us and to our entire planet. As the coastal ocean reporter for the LA Times, I find myself saying all the time that our planet is a planet of water, but we still tend to think about the environment in a very land-centric way.

In the story, we zoom into a very specific saga that happened off the coast of Los Angeles, starting with DDT and Rachel Carson’s Silent Spring. But that is truly just the beginning of layers upon layers of history showing how our disconnect from the ocean led us to where we are today — along every coast in the country and the world.

It’s interesting; I reread Silent Spring, which came out in the 1960s and sparked the modern environmental movement. DDT is, in many ways, the original “forever chemical” before that term even existed. Rereading Silent Spring decades later and seeing how these messages are still concerns and themes we’re living with today was striking.

We so often turn to the ocean for solutions that we hope will help solve our problems in the future. But how can we do that without realizing all the harm and pollution the ocean has already absorbed for us in past decades and generations? There’s no way we can truly think about solutions for the future without fully understanding what we’ve done in the past. That was an important through line we wanted to explore and share with the world in this film.

Daniel Straub: The historical footage of dumping that we have, none of it was hidden camera footage or exposés. It was documented and tutorialized. None of that was done as an exposé; it was just documentation of normal activities.

What was a horrifying revelation is that it wasn’t just a single disposal incident. All kinds of waste were being treated this way. There’s a line in the film from Tina Calderon, an Indigenous elder [Tongva and Chumash culture bearer] who says, “Until we reconnect with the Earth and the water that runs through our veins, we won’t stop causing harm.” That really started to resonate with me — reevaluating our relationship with the ocean. We rely on it for climate change solutions and food supply, but we don’t see it as a reciprocal relationship. We saw it as a place that could solve problems without regard to the harm that could be caused. This “out of sight, out of mind” mantra really dictated a lot of this practice, which is evident in the historical footage.

Mongabay: Let’s talk about DDT. What makes it a forever chemical? What does it mean to be a forever chemical?

Rosanna Xia: DDT was considered a wonder pesticide and was credited for playing a huge role in World War II because many soldiers were affected abroad by typhoid and other mosquito-borne diseases. After the war, it exploded in the commercial market, and we celebrated this chemical for a couple of decades.

Many folks have described DDT to me as the first forever chemical because it is powerful, potent, and indestructible — which makes it a great pesticide but also means it never really goes away. Once you put it in the environment, it takes a very long time to break down. Even when it breaks down, it continues to morph into other DDT-related chemicals that also pose problems. Scientists today have identified more than 45 related DDT chemicals.

People understand this concept when you talk about plastic. Plastic continues to break down into smaller and smaller pieces like microplastics, but it never fully dissolves or disappears from the environment. DDT is the first major forever chemical that we used, but certainly not the last.

One of the themes and questions we’re gently posing to the audience with this film is, “What are the DDTs of today?” We have a tendency in this country to have an “innocent until proven guilty” approach to chemical regulation, and the “proven guilty” part sometimes takes a very long time to manifest.

Mongabay: Can we clean up the DDT? Is it possible to remove it from the environment?

Rosanna Xia: Every time I ask that question to the folks in the field, they say we can’t really talk about solutions until we understand the full scope of the problem. Without giving away too much, we are still trying to figure out the scope of the problem, though we now know at least what questions to ask. Every time we go out and ask another new question, more questions arise.

There are some thoughts on what the solution might ultimately look like. Will it be cleanup versus figuring out where in the food chain we might be able to cut off the transmission of these chemicals before they continue to biomagnify and bioaccumulate further up the food chain? These are active questions that many great scientists are investigating.

In terms of other more immediate calls to action beyond cleanup, something this film brought into clarity for me is the power of long-term data sets. It’s not a sexy thing to say “this scientist needs a freezer for 80 years,” but consider this: In 2020, Professor David Valentine at UC Santa Barbara collected sediment samples from the seafloor. At the Scripps Institution of Oceanography, with NOAA down in San Diego, they have been systematically collecting sediment samples along the entire California coast and on the seafloor since the 1940s. Now they have a baseline for comparison. They can literally go back through the archives with samples collected decades ago without knowing what future questions they would need to ask. Now, they’re building a new data set within existing data to better understand the history of chemical deposition.

With the DDT issue, there’s another incredible project we follow where researchers at UC Berkeley had the foresight to start collecting blood samples from women since the heyday of DDT and then continue to follow their daughters and granddaughters. We have a multigenerational cohort of human subjects that can help us further understand the transgenerational impacts of these chemicals.

All of this takes foresight. In the film, you see Professor Valentine collecting more sediment samples from the seafloor, which will help inform questions in the future that we don’t even know to ask yet. That’s been profound to me: the handing of the baton from scientist to scientist over the years, and the consistency of these long-term data sets stored in freezers or jars of ethanol. The number of times Daniel, Austin and I went into spaces where things were shelved and archived with such meticulous diligence was remarkable.

Daniel Straub: Time is a recurring theme in the film, especially as it relates to these long-term archives. The questions we have about this issue that started 50, 60, 70 years ago — the only way to answer “what is the impact over time” is by having these long-term data archives that are expensive to maintain and whose purpose isn’t always clear until we need them.

These things can look frivolous and wasteful until you need them badly, and then it’s like having a time machine. How much would you spend to go back in time and gather this data to answer these questions? There’s no dollar amount that makes sense.

Part of understanding the implications of the problem now is understanding change through time. Is it getting better? Is it getting worse? What is the evolution of it? Without answers to those questions, you’re only getting a current snapshot of an issue, and you don’t know what factors are changing the issue over time.

It was incredible, as Rosanna mentioned, to go into spaces that very few documentary crews would be allowed into. Because of Rosanna and her long-standing relationships, they trusted us to film in these spaces. The day-in, day-out upkeep that it takes to preserve these collections is invaluable, and these people are heroes for capturing this data, preserving it, and making it available when scientists have new questions with emerging technologies that didn’t exist when the data was collected.

Mongabay: Rosanna, can you tell me more about the impact that your reporting on this topic has had?

Rosanna Xia: The first article prompted responses from Congress and remarkable action to kick-start the next steps we needed to take to ask the questions that would lead us to the ultimate question of what the solution is and how we address this problem.

A lot of the impact for me as a journalist happens before the article even comes out: the trust building, the community building, the connecting of dots. Just trying to write that first article, I needed to track down every researcher still studying DDT in some form and help all these researchers realize they were all asking similar questions.

The first time I called Dr. Eunha Hoh down at San Diego State University, she mentioned she had been seeing all these chemicals and DDT collecting in the blubber of marine mammals in Southern California. She had been wondering for years where all this DDT was coming from, since there are no new inputs because the chemical was banned in 1972. When I called her about these barrels, you could hear the “oh my God” moment.

As a journalist, I’m a bridge builder and dot connector. None of these stories would be possible without the amazing science and research that helps us find greater clarity about our past, present and future with our environment. We had some really great scientists who were also great communicators, which you can feel in the film.

We kept the team small, just the three of us in the field: Me, Daniel, and Austin. Daniel was both directing me and holding the boom mic. There was an intimacy there, and something I’ve been reflecting on and sharing with journalism students is that your first conversation with a source or scientist shouldn’t be the conversation for the quote. I had been talking to all these people for years before turning the camera on, and I think you feel that deeper level of connection and trust, which makes everything more relatable.

In terms of impact, I feel the community that this work has led to — there are working groups and task forces with members of the public, policymakers, and regulators all coming together in regular meetings to discuss this issue — the fact that it is prompting broader thematic questions urging us to reconsider our relationship to the ocean has been incredibly powerful.

Daniel Straub: I’ll say what she won’t: the public would not know about this story in the way that we do without Rosanna’s reporting. That is the only way this story made it to the public.

The impact has been incredible, and it’s the reason that this research is allowed to continue and funding was provided. My hope is that, through the work she has done, more funding will be made available and these issues can continue to be understood.

Mongabay: What are some of the choices or techniques that you used to fully immerse the viewer in the story and the environment?

Daniel Straub: Part of that comes from the way Austin [Straub] operates a camera. He has this philosophy of peering over the counter and watching someone cook, like when you’re a child observing. Being able to introduce that curiosity with the camera into the scientific process means we’re not set way back looking at science happening from a distance: it’s very intimate. We’re feeling and hearing the science take place on screen and seeing how the work is done.

A lot of people might want to sensationalize a story like this, and I’m really glad we didn’t. I’m incredibly proud that we created a film that didn’t have to compromise on journalism and science to be entertaining and engaging for an audience.

This is a tragic story, but it’s tragic because the environment where the story takes place is so beautiful. Being able to show these redwood forests, the ocean, or the cliffs near Big Sur, and present them as beautiful places was important to understand the stakes: this is what we stand to lose.

Banner image from ‘Out of Plain Sight’ film poster from Los Angeles Times/Sypher Studios

Liz Kimbrough is a staff writer for Mongabay and holds a Ph.D. in ecology and evolutionary biology from Tulane University, where she studied the microbiomes of trees. View more of her reporting here.

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