On the day Susan Gordon learned Venetucci Farm, in Colorado, was contaminated by toxins, the vegetables looked just as good as ever, the grass as green, and the cattle, hogs, chickens, and goats as healthy.
The beauty of the community farm she and her husband managed made the revelation all the more tragic. Chemicals known as per- and polyfluoroalkyl substances, invisible and insidious, had tainted the groundwater beneath her feet. PFAS had seeped into the soil from decades of training exercises that involved spraying firefighting foam at the nearby Peterson Air Force Base, in Colorado Springs. The hazard came to light when, in 2016, the US Environmental Protection Agency issued a health advisory recommending that drinking water have lower limits of two common types, PFOA and PFOS. Although the Air Force provided filters, the farm shut down in December 2017.
Once a symbol of American ingenuity, PFAS were originally conceived as wonder chemicals that could resist stains, repel water, extinguish horrific oil-based fires, and keep eggs from sticking to the pan. Today, we know them as a Frankenstein-like invention, zombie chemicals that will not die.
Chemists created thousands of such compounds by bonding carbon to fluorine in chemical chains, forging one of the strongest bonds ever discovered. Now they have been found across the planet—even in the blood of arctic foxes and polar bears. Public health studies found PFAS in the blood of about 95 percent of Americans. While the health impact of low levels of exposure is less clear, the chemicals are linked to liver, thyroid, and immune effects, cancer, and low birth weight. It will take billions of dollars—and yet more engineering prowess—to remove PFAS from drinking water and the environment. The task seems bleak, even as the US Department of Defense prepares to spend more than $2 billion on cleaning up PFAS on its bases. Firefighting training sites, airports, and industrial sites are also big contributors.
On Friday, the US House of Representatives passed the PFAS Action Act, which would require the EPA to set drinking water limits for two PFAS (PFOA and PFOS) and to designate PFAS chemicals as hazardous substances under the Superfund cleanup program. Its path forward is uncertain. Even if the Senate passes the measure, the Trump administration has called its provisions “problematic and unreasonable” and threatened a veto.
But here’s a shred of optimism: Some new technologies show promise in breaking those ultra-strong carbon-fluorine bonds, which means the compounds known as “forever” chemicals could be removed from at least some groundwater. “I have actually started to feel a little bit of hope,” says Chris Higgins, an environmental engineer at the Colorado School of Mines and a PFAS expert. “We’re getting some technologies that seem to be working.”
The most promising approach involves an electrical reaction that looks like lightning striking water. Contaminated water goes through a plasma reactor, where argon gas pushes the PFAS compounds to the surface. Electrodes above and below the surface generate plasma—a highly reactive gas made up of positive ions and free electrons—that interacts with the PFAS and breaks the carbon-fluorine bonds.
“Our goal is to completely destroy the compound and not just transfer it from one phase to another,” says Michelle Crimi, an environmental engineer at Clarkson University in Potsdam, New York, who works on emerging technology to remediate PFAS. The plasma reactor technique was developed by her colleagues Selma Mededovic, a chemical engineer, and Tom Holsen, an environmental engineer.
Crimi is also using ultrasound waves to create cavities—essentially holes—in the water. When they collapse, they instigate physical and chemical reactions that break apart the PFAS chains. Other researchers are working on electrochemical techniques and even soil bacteria that may metabolize PFAS.
Comments