PFAS are ubiquitous, found in everyday items such as nonstick cookware, microwave popcorn bags, fast-food wrappers, water-resistant clothing, furniture fabrics and carpeting.
At military installations, the chemicals are found in firefighting foam known as aqueous film-forming foam, or AFFF. The foam is used by DOD and other firefighting organizations to rapidly extinguish fuel fires, saving lives and protecting property.
In 2016, the U.S. Environmental Protection Agency issued a lifetime drinking water health advisory for perfluorooctane sulfonate, or PFOS, and perfluorooctanoic acid, or PFOA. PFOS and PFOA are only two of the hundreds of PFAS chemicals widely-used throughout the U.S.
The Defense Department has identified about 400 active and former military installations where there is a known or suspected release of PFOS or PFOA, and is taking actions to address PFOS and PFOA under the federal cleanup law. DOD also funds research projects to better understand how to cleanup PFAS.
Scientists attending the workshop on Sept. 26 spoke about some of the challenges of remediation.
Jennifer Field, a professor with the Department of Environmental and Molecular Toxicology at Oregon State University, studied PFAS for 25 years. "The scale of these things are really quite large," she said.
Her lab is trying to answer questions about where PFAS occurs in the environment. "We're specifically interested in military sites where AFFF have been applied," she said.
Remediation will be a challenge, she said, not only from a DOD perspective but on a national scale since the military isn't the only user of AFFF. Oil refineries and municipal fire stations and airports all trained with AFFF and have used it for decades.
There are many commercial products on the market containing PFAS, but the details of what is contained in those products "is proprietary information, which protects the company," Field said.
PFAS is persistent in the environment, she said, meaning it doesn't break down and degrade the way food waste does. It gets into the groundwater and, over time, goes into streams, fish and drinking water and then into humans.
Carpeting, upholstered furniture and other household items containing PFAS release it into the air inside homes. When the items are discarded, they eventually go to a landfill, she said. If the landfill isn't lined, PFAS makes its way to the drinking water. If it's lined, runoff from the landfill is channeled to a wastewater treatment plant.
Once the wastewater treatment plant processes it into biosolids, it's returned to a landfill or farmlands for crop production. That's how PFAS can get into corn and grass, and eventually into milk. It's a cycle with a lot of pathways, Field said.
It's like pulling back the layers of an onion to understand where the PFAS is and where it could eventually be. If it's not already in the drinking water but the soil, sometimes it takes a while to get to the water table, so water that's PFAS free now might eventually contain it, she said.
DOD is the key source of PFAS remediation funding in the U.S., Field said. "It's a large-scale, coordinated effort to address this very large problem. Taxpayer dollars are being used to understand a complex problem that's accumulated over many years and that problem transcends the military."
Christopher Higgins, a DOD-funded professor of civil and environmental engineering at the Colorado School of Mines has been working on PFAS transport and exposure in the environment since 2001, monitoring PFAS in the soil and groundwater.
As for remediation of drinking water, he said there are many options, such as PFAS-free bottled water, reverse osmosis systems, carbon filters and ion exchangers used to treat the water.
Depending on the soil topography, it could take years before the PFAS moves into the drinking water source where it can be detected, he added.
However, if PFAS finds its way into food, that's a problem that's not as easy to remedy. If food packaging materials contain PFAS, that can be quickly changed by industry, which has already been making inroads to eliminating PFAS from some products, he said.
"It takes a lot of time and resources to investigate a source zone where these compounds have been released because they're fairly complex," Higgins said. "Often, there have been multiple releases of chemicals over many, many years, different types of chemicals have been applied over many years and in some cases, these sites have actually been cleaned up for other contaminants other than PFAS and all of those things can impact both the composition of the chemicals and PFAS as well as their distribution. Unraveling all that takes time, resources and expertise."
Higgins said his work requires a collaborative effort with a broad set of expertise, to include soil chemists, hydrologists and people focused on groundwater transport or bioaccumulation.
"DOD encourages us to work across disciplines and outside our university, even at locations throughout the world to get the best minds to address this," he said.
The department has been very proactive in addressing PFAS, he said. In 2009, the Environmental Protection Agency first issued its provisional health advisory. Within a year, DOD was funding testing and remediation projects.
Higgins said he hopes the work he and his fellow researchers do will be a model for the rest of the U.S., not just inform what’s happening at DOD sites.
"This isn't just a DOD problem," he said. Sites impacted by PFAS can be found nationally.
Elsie M. Sunderland is Gordon McKay Professor of Environmental Chemistry at Harvard University. She said most people have some level of PFAS in their blood. In a study released in 2007, researchers from the Centers for Disease Control and Prevention tested blood samples from more than 2,200 participants in the National Health and Nutrition Examination Survey and found that 98% of the samples contained some levels of PFAS.
"We're at the beginning of an exponential increase in our understanding of these chemicals and interaction with people and the environment," she noted.
The broader effort is to bring together researchers, government at every level, and academia to better understand the problem and develop courses of action, Sunderland said, adding that DOD has been the catalyst for this effort.