Hakai Magazine

a plane sprays chemical dispersant over oil coated Gulf of Mexico after the Deepwater Horizon spill
Crews charged with cleaning up the Deepwater Horizon oil spill sprayed a record amount of chemical dispersants on the Gulf of Mexico via planes and boats. Photo by Benjamin Lowy/Getty Images

A Key Tool for Cleaning Up Oil Spills Is More Hazardous Than Helpful

In the decade since the record-breaking use of oil dispersants in the Deepwater Horizon oil spill response, science shows they’re dangerous, potentially deadly, and rarely useful. A new court case is forcing the US EPA to reconsider their use.

Authored by

by Ryan Stuart

Article body copy

When most kids in Arabi, Louisiana, were spending their summer holidays sleeping in and playing baseball, George Barisich was working. Starting when he was 10 years old, Barisich was an apprentice aboard his dad’s fishing boat, a wooden trawler, launched the same year he was born. In his family, kids worked. “As long as you could swim,” Barisich laughs. “Those were the rules.” If you got seasick, like Barisich sometimes did, that was life as a fisher.

They would motor out a channel to bigger water and chase shrimp along the Gulf of Mexico coast to the border with Texas. He and his brother eventually took over running the boat. Like their dad, they shrimped from May until Christmas. They also started oyster farming in sheltered waters about a four-hour boat ride away. Now a slim 65, with sun-carved wrinkles and a neat salt-and-pepper mustache, he doesn’t get seasick anymore. But fishing hasn’t gotten any easier.

“My old man was rough, but I’m glad he was hard on us. Otherwise, I don’t think I would have survived everything I’ve survived,” Barisich says. Hurricanes, recessions, his boat catching fire. But none of these prepared him for a disastrous oil spill, nor the cleanup that followed.

On April 20, 2010, an explosion on BP’s Deepwater Horizon oil drilling platform killed 11 people. When the platform sank, the wellhead pipe on the seafloor ruptured, leaking perhaps as much as 7.8 million liters of oil into the Gulf of Mexico over the next three months. A massive oil slick fouled the coast from Texas to Florida, and particularly Louisiana’s. Barisich was forced to stop fishing and his health deteriorated.

Deepwater Horizon Fire, April 21, 2010

In April 2010, an explosion rocked the Deepwater Horizon oil rig, causing a fire and the spill of as much as 7.8 million liters of oil. Photo by Science History Images/Alamy Stock Photo

“I was a healthy son of a bitch before,” he says, in a Louisiana drawl. “I could run my boat by myself. Now, I need one or two deckhands. I have half my breathing capacity.”

Barisich is angry at BP for the oil spill and the subsequent use of a commercial product called Corexit. Corexit is one of the best-known dispersants, a class of chemicals formulated to break up oil slicks in the ocean. During the Deepwater Horizon cleanup, a record 6.8 million liters of Corexit were dumped into the Gulf.

Even before 2010, scientists were raising concerns about Corexit’s safety and efficacy. A decade later, there is even more evidence against dispersants like Corexit, yet they remain a key tool for oil spill responders in jurisdictions around the world.

For oil spills at sea, cleanup crews rely on four main techniques: contain and slow the oil spread with booms, collect what they can with boats that skim oil off the surface or with absorbent pads that soak it up, burn the oil on the water, or sink it with chemical dispersants. The choice of which to use depends on many factors, including the type of oil, weather and sea conditions, proximity to sensitive habitat, and resources available. Crews often use more than one technique at the same time. Each has pros and cons, but none is as controversial as the chemical dispersants.

In the Gulf, crews applied dispersants to break up surface slicks and reduce the chances of oil contaminating coral reefs or marshes or impacting surface-dwelling animals. Usually applied from the air, the chemicals are mixed with the floating oil by wind and waves, breaking the cohesive slick into microdroplets that disperse through the water column in parts per million or even per billion.

But it’s a trade-off. Dispersants contain chemicals that are considered toxicants, and they impact natural oils, too, like the ones on human skin. The dispersed oil is more likely to impact ecosystems below the surface and at the seafloor.

That’s why organizations and companies tasked with preparing for marine oil spills carefully plan where and when to use dispersants, says Matthew Sommerville, a member of the executive committee of the nonprofit International Spill Control Organization. For example, a regional cleanup plan would include advice to avoid applying dispersants near coral reefs, spawning fish, nesting birds, or migrating marine mammals or in situations where currents would carry them toward sensitive areas, and to apply them only in the right weather conditions, when they can be effective.

The advice stems from the checkered history of dispersants. The first documented use of a chemical mixture, an earlier version of Corexit, was after the 1967 Torrey Canyon spill off England’s coast. Even then, scientists had concerns about the toxicity in the marine environment, prompting governments to develop new guidelines for use and push for less harmful formulations. Yet, over the years, dispersants crept into the toolkit of most spill response organizations around the world.

Within days of the Deepwater Horizon spill, crews sprayed dispersants on the growing slick from boats, helicopters, and airplanes. But because the oil was spewing out of the seafloor, BP asked for permission to apply Corexit at the wellhead. The US Environmental Protection Agency (EPA) and the US Coast Guard approved the idea, and in an experimental effort, cleanup crews injected the dispersant 1,600 meters under the water surface in an effort to disperse the oil before it hit the surface.

a plane sprays chemical dispersant over oil coated Gulf of Mexico waters after the Deepwater Horizon spill

Many describe the spraying of chemical dispersants as disaster theater—a gesture that was ineffective and potentially dangerous. Photo by Benjamin Lowy/Getty Images

Over the duration of the spill, an estimated 7,000 cubic meters of dispersants went into the Gulf, about a third of this volume at the wellhead, according to a report on the spill and cleanup. Barisich and other Gulf Coast residents say dispersants were also sprayed close to shore and near boats. (BP denies the allegations.) “They kept saying they weren’t,” Barisich says, but he fished immediately after the spill, and when the fishery closed, he worked the cleanup effort and was on the water every day.

Barisich isn’t the only one with health issues in the aftermath, says Wilma Subra, a technical adviser to the Louisiana Environmental Action Network, a nonprofit that advocated for affected communities during the Deepwater Horizon cleanup. Subra documented dozens of illnesses tied to the oil spill and Corexit. The most common were respiratory problems, confusion, kidney and liver damage, and skin and muscle issues, but there were also reports of seizures, paralysis, and rare cancers. “Many families living in coastal areas are sick and a lot of the cleanup workers are, too,” says Subra. “They can’t work. [Some have] lost their cars and houses. It has destroyed hundreds of families.”

Sorting out causes is tricky. Many of the people who say they were exposed to dispersants were also exposed to oil. Dispersants have toxic effects on their own and they exacerbate the toxic effects of oil, because they enhance its skin penetration, says Subra. For some symptoms, the trauma of the disaster could also be a factor.

Researchers have conducted thousands of studies on the spill, cleanup, and aftermath. Only a small percentage considered human health impacts. Still, some connect Corexit to sickness and death. A paper published in the journal Environmental Health Perspectives in 2018 found that people exposed to dispersants and oil were more likely to suffer with coughing, wheezing, and shortness of breath. A separate study of US Coast Guard employees, published in 2019, found that oil spill workers were more likely to suffer long-term illnesses if they were exposed to dispersants. Researchers at the Johns Hopkins Bloomberg School of Public Health reported in 2018 that dispersants decreased the risk of cancer caused by oil toxicants like benzene, but they increased the volatile organic chemicals people were breathing in by 10 times.

At the same time, there are increasing concerns that Corexit doesn’t do what it’s supposed to do.

In 1989, the Exxon Valdez oil tanker famously ran aground in Alaska’s Prince William Sound, spilling 42 million liters of oil. A few days after the spill, cleanup crews tried using dispersants on the spill, but they stopped when it was obvious they weren’t working.

Still, many cleanup workers say the chemicals left a legacy of illness. Studies tracked high rates of liver, kidney, lung, and nervous system issues among the employees and volunteers who worked on the spill and were exposed to the dispersants.

The disaster and the botched cleanup led the US Congress to create two citizen advisory councils for the waterways where ships move most of Alaska’s oil, Prince William Sound and Cook Inlet. The groups make recommendations for oil spill preparedness in Alaska and regularly hire experts, like independent spill specialist Merv Fingas, to review research. Concerned that using dispersants remains a tool in cleanup operations, the group hired Fingas in 2017 to review relevant research.

Exxon Valdez surrounded by oil from its spill

The botched cleanup effort after the Exxon Valdez oil tanker ran aground in Alaska’s Prince William Sound, spilling 42 million liters of oil, led to the creation of citizen advisory councils for the waterways where ships move most of Alaska’s oil, Prince William Sound and Cook Inlet. Photo by RGB Ventures/SuperStock/Alamy Stock Photo

Of more than 200 studies, Fingas found 78 percent showed that chemically dispersed oil was more toxic to marine life than oil left to break down naturally. Of those that examined biodegradation, 67 percent showed that the addition of dispersants actually decreased the ability of microbes to eat oil. Just 22 percent of the studies showed positive results; according to Fingas’s report, the petroleum industry funded all of those.

Only in rare situations are dispersants helpful, says Jeffrey Short, a consultant who worked for litigants fighting BP after the Deepwater Horizon event. “They have a role to play,” he says. “The right dispersant, with the right oil, with the right wind conditions, in the right place—it works pretty well.” But dispersants only work on oil that’s fairly fresh. Just getting the dispersants to a spill within the first couple of days is often impossible. And the weather window for effective application is small. Most of the time, Short says, their use is “response theater,” something overwhelmed cleanup crews can do to prove they’re trying everything.

As long as oil drilling and transport take place at sea, there’s going to be pressure to include dispersants as part of spill cleanup plans, says Short, because no other tools do what they do. Grand View Research, a marketing and consulting firm, expects spending on global oil spill preparation to grow from US $153-billion in 2020 to $178-billion by 2025. Short notes that researchers are looking for dispersant alternatives, including clays that grab and sink oil to the seafloor. None is ready for commercialization.

A recent court case may add some momentum to efforts to improve dispersants or discontinue their use. Rules in the United States say the EPA must keep the federal Clean Water Act in line with the latest science. But the EPA has not updated its rules on dispersant use since 1994, well before Deepwater Horizon. A coalition of environmental groups and individuals, with the Environmental Law Clinic at the University of California, Berkeley, as lead council, sued to change that. In August 2021, a US federal judge ruled in their favor. The EPA must now review the science and create new response rules by May 2023.

The plaintiffs believe the new plan will look radically different from the 1994 plan, says Claudia Polsky, director of the Environmental Law Clinic. They think dispersants will become the last resort in a cleanup.

The people most impacted by the Deepwater Horizon spill hope that’s true. Many coastal residents continue to struggle with health issues, beaches remain toxic, and marine species decimated by the spill have not recovered. George Barisich is back fishing and oystering, but harvests are only a fraction of what he hauled in before 2009. “I call Corexit the illusion solution to pollution,” Barisich chuckles, before growing serious. “There’s got to be a better way.”