



Five years ago this week, the Deepwater Horizon oil rig exploded, killing 11 workers and setting off the worst oil spill in US history. The images are unforgettable: The Gulf of Mexico on fire. Pelicans emerging from the water entirely covered in thick, black oil. Planes flying overhead, spraying more than a million gallons of an oil-dispersing chemical called Corexit in an attempt to control the spill.

Fast forward five years, and dispersants like Corexit are at the center of a growing political battle, as scientists and policymakers raise questions about their potential to harm the environment, wildlife, and human health. Right now in Washington, DC, the Environmental Protection Agency is developing new rules governing dispersant use—rules many experts worry won’t go nearly far enough to protect the public and natural resources. On Tuesday, Rep. Jerrold Nadler (D-N.Y.), introduced legislation to temporarily ban dispersants until more tests are done to guarantee their safety.

A recent study found that Corexit can harm human lungs and marine life.

Corexit is a go-to product for energy companies like BP when they’re dealing with massive spills. Dispersants don’t actually get rid of oil. But by breaking the oil up and submerging it in the water column, the chemicals make it easier for microbes to consume the oil. At least in theory. These days, some scientists are raising questions about how effective the 1.8 million gallons of Corexit dumped into the Gulf really was in achieving this. Dispersants have other benefits for oil companies, though. By moving oil out of sight, they quell public fears, facilitate PR, stabilize stock prices, and—potentially— help the polluters avoid stiff fines.

But all that Corexit may have done significant damage in the Gulf. One 2012 study found that in laboratory tests, mixtures of Corexit and oil were up to 52 times more toxic to microscopic animals known as rotifers than oil alone. Several leading scientists believe that the use of dispersants contributed to the environmental catastrophe that occurred throughout the Gulf, including the destruction of coral reefs. Studies have found that dispersants—as well as dispersant/oil mixtures—are more deadly to coral and coral larvae than oil by itself. A new report from the Government Accountability Project, a national whistleblower organization, describes the damage to Gulf coral as “arguably the most devastating and revealing of impacts documented in the five years since the BP spill.” This is particularly significant because coral reefs form a natural barrier against hurricanes and provide a habitat for thousands of marine species.

There may be risks for humans, too. A 2013 study in the American Journal of Medicine found that “clean-up workers exposed to the oil spill and dispersant experienced significantly altered blood profiles, liver enzymes, and somatic symptoms.” The researchers cautioned that their study did not establish what caused these symptoms, but they speculated that “the effect of the oil dispersant may have contributed” to their findings. In an email, a BP spokesman countered that this study has “numerous flaws,” including that the participants classified in the study as “exposed” to the spill and dispersant had been referred for evaluation by legal counsel.* The same journal subsequently published two criticisms of the study, one of which stated that “both groups in their study, unexposed and exposed, have clinical biomarker values for both liver function and blood profiles that essentially fall within the normal ranges for healthy adult individuals.”

A 2015 study by University of Alabama at Birmingham researchers that was published in the journal PLOS ONE concluded that Corexit can harm human lungs and marine life. The researchers found that Corexit exposure can damage tissue and suggested that it may “exacerbate the symptoms caused by pre-existing respiratory illnesses such as asthma.”

“There were some 48,000 workers involved in the cleanup operations, and it is possible that workers were exposed to Corexit via inhalation,” said Dr. Veena Anthony, the study’s senior author, in a press release. “Cough, shortness of breath and sputum production were among symptoms expressed by workers.”

The BP spokesman notes that the Alabama paper “provides no data to suggest that response workers or aquatic life were exposed to harmful levels of dispersants in the wake of the Deepwater Horizon accident. The laboratory study focused not on whether dispersants had an impact in the Gulf, but on how a respiratory effect could occur and how any such effect could be counteracted.”

The BP spokesman also pointed out that the company’s use of dispersants “was coordinated with, and approved by, US federal agencies,” including the EPA and the Coast Guard, and added that BP worked with government agencies “to take extraordinary measures to safeguard the health and safety of responders.” According to the spokesman, workers were provided with safety training and protective equipment, including respirators. The spokesman added: “Due to the extensive controls in place, there was little potential for worker or public exposure to dispersants. More than 30,000 air monitoring samples were collected by the Coast Guard, OSHA, NIOSH, and BP as part of a comprehensive air monitoring program to evaluate the potential for human exposure to dispersant and oil compounds. The results showed that response worker and public exposures to dispersants were well below levels that could pose a health or safety concern. Extensive monitoring conducted by federal agencies and BP show that response workers and the public were not exposed to dispersant compounds at levels that would pose a health risk.”

During the spill response, Corexit wasn’t just applied to the crude on the surface. As the oil gushed from the well, BP rushed to apply 771,000 gallons of Corexit directly to the wellhead in an attempt to disperse the oil before it could even make it to the surface. Then-EPA chief Lisa Jackson described this procedure as “a novel approach.”

Following that experiment, the development of underwater dispersant systems has become a major project for the oil industry. That has researchers concerned. “The science is coming in that there are terrible irreversible effects, but the regulatory agencies are not paying attention,” says Susan Shaw, an environmental health scientist who runs the Marine Environmental Research Institute in Maine. “Why do we want to keep going with an experiment that harms wildlife?”

“Why do we want to keep going with an experiment that harms wildlife?” asks Susan Shaw of the Marine Environmental Research Institute.

Dispersants weren’t always the focal point of disaster response. The National Contingency Plan, first created in 1968, set out protocols for responding to serious oil spills. When the plan was written, it specified “containment” and “removal” as the top priority during a spill. In practice, this translates into skimming and suctioning oil, which is the priority in other industrialized countries. In much of Europe, for instance, state-of-the-art tankers are used to suck up oil. The plan permitted the use of dispersants only “if other control methods are judged to be inadequate or infeasible, and if certain information requirements and usage requirements were met,” according to the EPA.

But in the 1990s, after what was then the worst maritime disaster in American history—the Exxon Valdez spill in Alaska—this orientation began to shift. Federal regulators revised the contingency plan to preauthorize the use of dispersants, a change that gave polluters significantly more influence in determining whether to utilize them. Since then, the popularity of dispersants has skyrocketed; the industry now considers them the primary tool in its “recovery” toolbox.

“In essence, dispersant use became institutionalized as part of, and integrated into, this new national response system,” writes Riki Ott, a marine biologist and environmental activist, in her book Sound Truths, Corporate Myths. “Meanwhile, the science continued to build, showing evidence of harm to wildlife and people from dispersant use.”

In January, nearly five years after the Deepwater Horizon explosion, the EPA finally published proposed rule changes that it had been working on since 2001. The new rules would mandate more rigorous testing and monitoring of cleanup products and would create a public process for removing ones that don’t work as expected or that harm humans or the environment. But some experts are concerned the rules won’t do enough to restrict dispersants. “Science isn’t leading policy, industry is,” says Ott. “It’s the tail wagging the dog.” Ott argues that the proposal would give too much power to oil companies and the Coast Guard to determine when and how dispersants should be used and would effectively sideline local officials and citizen groups. It “would limit the number of players at the decision-making table during an actual response,” she says.

Cyn Sarthou, the executive director of Gulf Restoration Network, concurs. “We’ve already seen what firebombing the Gulf with dispersant from above and below can do,” she says. “Nobody who cares about the environment, wildlife, or human health wants to repeat that. Decisions should be made by scientists and people whose livelihoods are dependent on a healthy environment, and this rule does not provide for that.”

The public comment period for the new rules closed this week, and environmental groups pulled out all the stops in urging their allies to contact the EPA. “Now is the time to tell the agency that we must have the strongest possible protections from toxic oil dispersants,” wrote Earthjustice, an environmental legal group, in an action alert on its website.

“Decisions should be made by scientists and people whose livelihoods are dependent on a healthy environment,” says Cyn Sarthou of Gulf Restoration Network, “and this rule does not provide for that.”

In an interview on Tuesday, Rep. Nadler called the EPA proposal “totally inadequate.” He’s currently seeking Republican co-sponsors for his bill, which, according to his office, would put the use of dispersants on hold. “What we need are definitive studies on people and other life forms impacted by dispersant and the combination of oil and dispersant,” Nadler says. “Pending the results of such studies, dispersants should not be allowed.”

For many environmentalists, one of the more vexing aspects of the proposed rule change is the EPA’s refusal to define dispersants in a way that reflects how they really work. The rules prohibit traditional “sinking agents” such as sand and clay because they sink oil to the seafloor and damage the marine environment. Chemical dispersants aren’t heavy enough to be considered sinking agents, but they do facilitate the sinking of oil into the water column. This is no doubt one reason the oil industry likes them so much. During the Deepwater Horizon disaster, Corexit played an instrumental role in creating the illusion that the oil had disappeared.

Perhaps the most alarming facet of the proposed rules is that they accept the subsea use of dispersants as a viable cleanup strategy. In its comments to the EPA, Earthjustice raised concerns about “significant knowledge gaps” pertaining to the “potentially toxic effects” of subsea dispersant use on the deep sea environment. The group called on the EPA to ban or heavily restrict the practice.

Jeffrey Short—a former research chemist at the National Oceanic and Atmospheric Administration and former Pacific science director of the watchdog group Oceana—was one of several scientists invited to attend an EPA meeting in the first weeks of the BP disaster to determine whether to apply Corexit underwater.

While he supported the decision at the time, Short says his opinion was based on information about a trial application presented by the EPA—but he says that in the field, the dispersant probably did not work as intended. He now believes that subsea use is superfluous because the mechanics of a blowout combined with the drop in temperature and pressure at depth creates a natural dispersion of oil. “You could see the oil dispersing as it emanated from the risers,” says Short, referring to the video feed that riveted the nation for months. “That process alone accomplished what they hoped to accomplish through the use of dispersants. It’s like taking a can of Coke, shaking it up and opening it. It goes everywhere.”

A 2010 study by scientists at the US Naval Research Laboratory revealed another potential limitation to Corexit’s effectiveness: It actually harms microbes that are adapted to consume oil. The study’s authors concluded that dispersants “could potentially diminish the capacity of environmental microbial communities to bioremediate the spill”—thus negating one of the industry’s prime justifications for using them.

What’s more, by sinking oil into the water column, dispersants merely delay the process of its washing ashore. Oil, and oil mixed with dispersant, is churned up during storms, forming tar mats and tar balls that contaminate beaches—and will continue to do so for decades to come.

Despite all of this, the oil industry is pushing ahead on dispersants. In July 2010, as the Macondo well continued to gush oil into the Gulf, ExxonMobil, Chevron, ConocoPhillips, and Shell collaborated to create the Marine Well Containment Company, which engineers and builds oil well caps. The company recently announced a new system that not only caps a broken wellhead, but also includes large containers of dispersant, pre-installed on the sea floor, that can be remotely activated in the event of an oil spill.

“The industry is attempting to normalize its use of subsea dispersants, which could hide the existence and scope of future oil spills,” says Rep. Nadler.

Jonathan Henderson, the field operations manager of Gulf Restoration Network, worries that the Gulf is at even greater risk today than it was before the BP spill. That’s because oil companies are drilling deeper wells than ever before. “In a loss-of-well-control situation in [an extremely deep well], if the newly designed blowout preventer fails, or the capping stack doesn’t work, then what?” asks Henderson. “Millions of gallons more of toxic dispersants?”

This article was reported in partnership with The Investigative Fund at The Nation Institute, with support from the H.D. Lloyd Fund for Investigative Journalism. Credit for the organization that provided support for the reporting was originally misstated.

Correction: This article originally stated that BP did not respond to requests for comment. In fact, a BP spokesman did email a response. We have revised the story to include comments from BP.