Future Tense

Firefighting Chemicals Are Dangerous for the Environment. Can That Change?

A close-up view of cracking glass
Photo illustration by Slate. Photo by Getty Images Plus.

A journalist who covers wildfires responds to Premee Mohamed’s “All That Burns Unseen.”

In “All That Burns Unseen,” set in a dystopian but not-too-distant future, we finally get the drone sidekick we didn’t know we needed. Premee Mohamed’s heroine, Vaughn Collins, is a government worker gone rogue as a wildfire burns. Along the way, she rescues a dazed, glitchy fire extinguisher drone. When a funnel of flames heads for Vaughn’s truck, threatening everything, her new friend dives into the blaze and sprays.

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I understand her affection for it. When the world is too much, I’d like to humbly recommend fire drone YouTube. Drones can spot forest fires, find people behind flames, and pull firehoses up beyond the tallest ladders. Some, like this little guy, are essentially flying fire extinguishers.

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Vaughn’s enthusiasm for her drone friend is dampened only by the chemicals it contains. “Supposedly they were less dangerous than they used to be. Vaughn still didn’t like the idea of breathing the stuff in,” Mohamed writes. In our present and in Vaughn’s past, the chemicals in some firefighting foams, known as PFAS, are indeed dangerous. What replaces them could depend on today’s Environmental Protection Agency.

In firefighting, different fuels call for different chemicals and techniques. Class A fuels, like wood or paper, can be put out using water, often made even more effective with additives. You’re probably familiar with Class A fire retardants from photos of air tankers dropping red clouds near wildfires; they slow oncoming flames by changing how they burn. To be clear, these are different from PFAS—although they have their own risks. Made of salts or chemicals used to make fertilizer, they have killed fish and caused algae blooms; their use is now restricted near water.

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But at least these Class A wildfire retardants should break down over time. When I asked Shirley Zylstra at the U.S. Forest Service, she told me that they “lose most or all of their toxicity within a month or so.” So do the Class A foams used to fight wildfires up close, which are made of detergents like those in shampoo or shaving cream; they help water sink in and coat buildings in protective bubbles. Like retardants, “Class A” foams are also short-term bad for fish; on the upside, they are required to biodegrade quickly. (In case you were wondering, home fire extinguishers shouldn’t have long-term effects, either. Their powders smother grease and electrical fires as well as Class A fires. White powder is basically baking soda; yellow is chemically close to bird poop.)

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Vaughn’s drone sprays black powder. It could be carrying fire extinguisher powder. Or, if the drone also carries water, it could be carrying a futuristic foam concentrate. As Vaughn points out, first responders should avoid breathing any of this stuff in. Many of these chemicals could cause coughing, irritation, or even death at high-enough doses. That said, they are deeply diluted before use. Opponents would like Class A foams and retardants used less, but they are not focused on making the chemicals themselves less harmful.

When Vaughn says firefighting chemicals have become less dangerous, then, she may be talking about a different category: aqueous film forming foams, or AFFFs. Invented in the 1960s, these foams protect jet fuel at airports and oil at refineries. They are our best tool for Class B fires: when vats of flammable liquids catch flame. In Mohamed’s story, Vaughn lands her plane on an oil company runway. Perhaps her manta ray–shaped drone sidekick, fighting fires in a land filled with flammable liquids thanks to the oil industry, is carrying a futuristic replacement for AFFF. But what, exactly?

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Like the fossil fuels they protect, AFFFs cause long-lasting harm. Instead of killing fish quickly, they give fish cancer. In Lake Superior, chemicals used in AFFFs have made some fish dangerous to eat, affecting tribal fishing traditions and people who fish to survive. Across the U.S., these chemicals are contaminating drinking water. What’s worse, they essentially never break down.

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Called PFAS (for per-and polyfluoroalkyl substances), these “forever chemicals” repel both water and oil. They form weirdly impenetrable firefighting foam; they also give us waterproof mascara, rainproof tents, leakproof burger wrappers, and nonstick pans. But in addition to repelling liquids, PFAS also accumulate in our blood. Most of us have at least some PFAS in our bodies.

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You’ve probably heard about them before. In 1999, mysterious cow deaths near a DuPont factory sparked class-action lawsuits and medical research into the impacts of PFAS. The 2019 film Dark Waters follows lawyer Robert Billot, played by Mark Ruffalo, who won several lawsuits against DuPont, which knew there were risks for years.

Independent research ordered during those lawsuits linked high levels of PFAS to thyroid problems, pregnancy complications, kidney disease, and more. Since then, even low levels have been connected to immune system problems and other health concerns.

PFAS were first developed in the 1930s and are still used widely. But AFFFs are one of the most obvious ways they wind up in our water. For years, fire departments could simply hose huge, foamy mounds of AFFF into soil and storm drains. Eventually, many states tightened guidelines for disposing of foam.

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In the early 2000s, chemical companies started phasing out early PFAS called PFOS and PFOA, replacing them with ostensibly less-bad alternatives. Newer “short-chain” PFAS are different than their predecessors on a molecular level, so existing research about risks did not as clearly apply. Many municipalities did what seemed like the right thing: They switched to firefighting foams made with the newer PFAS.

Now, it appears many of the newer PFAS are still plenty bad for us. Many fire departments will have to replace AFFFs again, this time with non-PFAS foams. In the meantime, we’ve spent two decades using replacement chemicals in all sorts of products that are still toxic and that still persist in the environment.

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It’s the kind of seemingly preventable mistake that makes teeth grind. But in the chemical industry, these “regrettable substitutions” are common. Vaughn’s skepticism toward the contents of her drone is warranted: The same thing could easily happen again.

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Reasonable people might expect chemical regulation to work something like drug approvals. To release drugs (or vaccines) companies must first run—and pay for—study after study to clarify any side effects. For the U.S. chemical industry, for a long time, the process was almost the opposite. For decades, most new chemicals entered the market with no required safety testing and no formal review by the U.S. EPA.

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Under the 1976 Toxic Substances Control Act, chemicals were assumed safe until proved dangerous. The EPA had limited power even to request data. Once it understood health risks, it had to weigh them against financial costs. When the EPA banned asbestos in 1989, manufacturers sued to weaken the ban and won.

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Now, there is a glimmer of change. In 2016, Toxic Substances Control Act reform finally passed. A bipartisan bill, the Lautenberg Act, gave the EPA more authority to test and regulate new and existing chemicals—and required it to do so. In June, the EPA finally proposed a new asbestos ban; it also ordered safety tests for 6:2 FTAB, one of the “short chain” PFAS now used in AFFF.

A week later, the EPA also announced health advisories for four other PFAS. The new “safe” level for PFOA and PFOS in drinking water is approximately zero. Next, the EPA plans to designate those two PFAS as hazardous. That move will trigger Superfund cleanups and big decisions about who will pay.

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For the first time, the EPA also defined safe drinking water levels for two of the newer “short chain” PFAS; enforceable limits should follow. Surely now we can rest easy, knowing that Vaughn’s well-meaning drone sidekick, decades in the future, is spraying something truly harmless?

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The problem is, none of this actually bans the PFAS in AFFFs. PFAS are still used in Class B firefighting foams because they still put out liquid fires faster than alternatives. The Department of Defense has a mandate to find non-PFAS replacements by 2024, but so far it doesn’t have a silver bullet.

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More broadly, drinking water limits alone can’t solve for regrettable substitutions. There aren’t just four PFAS chemicals—there are thousands. The EPA can’t even test for them all yet. While this year’s four health advisories were based on clear, if limited, data, most PFAS are entirely unstudied. They may be better or worse than their predecessors; we don’t know.

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That’s why some toxicologists want the EPA to regulate PFAS as one big group. As with drugs, they think PFAS should be assumed dangerous until proved safe. Because PFAS don’t biodegrade and we can’t study them quickly enough, continuing to produce them multiplies problems we don’t yet understand. Add all the other chemicals we can’t keep up with, and we may even be threatening the stability of life on Earth. (Again, may I recommend a delightful firefighting drone video as a break from the news?)

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A handful of states, like California, are already regulating PFAS as a group, banning them in product categories like food packaging. The EPA is taking a different tack, working first to better understand the specific risks of different PFAS subgroups.

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Using computer models and machine learning, computational toxicologists can treat PFAS molecules like keys and virtually test them against receptors in our cells. PFAS that are likely to accidentally unlock similar cellular functions can be grouped and prioritized for research. Data from the 6:2 FTAB used in AFFF, for example, could help the EPA make educated guesses about the health risks of 503 other structurally similar PFAS.

This approach could clarify health risks and help justify eye-popping cleanup costs—it could also take decades. In an email, the EPA said the agency “is focused on improving its ability to address multiple chemicals at once.” In the dystopian future Mohamed imagines, Vaughn’s continued skepticism implies plenty of “regrettable substitutions” in the meantime.

Future Tense is a partnership of Slate, New America, and Arizona State University that examines emerging technologies, public policy, and society.

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