LIMESTONE, Maine — An Aroostook County tribe has found that industrial hemp plants will extract so-called forever chemicals from contaminated soil on land it owns at the former Loring Air Force Base.

There’s one problem: no one can figure out what to do with the hemp.

“There hasn’t been a way to get the PFAS out of the plants without it going back into the environment,” said Mi’kmaq Nation Vice Chief Richard Silliboy.

Finding a way to take per- and polyfluoroalkyl substances, known as PFAS, out of contaminated hemp plants without unintentionally releasing them into the air is the next step in the tribe’s effort to remediate 650 acres of polluted land the U.S. government turned over to it 15 years ago.

Using hemp plants to suck up PFAS from the ground has been touted nationally as a potential fix for the widespread pollution. But the Maine tribe’s experience has revealed a significant obstacle to making it work. Testing will soon be underway to try to find a solution to the roadblock.

PFAS refers to a group of manufactured chemicals often found in household and personal care products that have polluted soil and water at former manufacturing sites. Known to break down slowly, the long-lasting “forever chemicals” have been linked to increased risk of some cancers, issues with hormonal and immune systems, developmental delays in children, and other health issues, according to the Environmental Protection Agency.

The land the federal government gave the Mi’kmaq Nation in 2009 was so contaminated it was designated a federal Superfund site. The Mi’kmaq property used to be a key training area for Loring firefighters, who used a PFAS-laden foam.

In 2019, Silliboy and Chelli Stanley co-founded Upland Grassroots, an organization dedicated to cleaning up the Mi’kmaq parcel. Stanley, who lives near Hallowell and has a background in community organizing, learned about hemp-based PFAS extraction and contacted Silliboy, who was immediately interested in its potential.

That year, Stanley, Silliboy and other tribal members planted and harvested several small plots of hemp plants on the Loring property. They sent the harvested hemp to the Connecticut Agricultural Experiment Station, a state-run scientific research facility.

Initial data showed that the hemp plants were extracting various forms of PFAS, including perfluorooctanesulfonic acid, or PFOS. In summer 2022 the group planted five larger plots, with four hemp varieties grown in smaller subsections within each plot.

Of the 28 PFAS varieties identified in the soil, 10 were found in the harvested hemp plants, according to the group’s research published earlier this year.

Stanley and the Mi’kmaq Nation want to eventually expand the number and size of hemp plants to test for larger extractions of PFAS. But without a safe method to dispose of the PFAS-laden hemp, the group’s research can only happen on a smaller scale.

“We don’t want to put the hemp in a landfill and have it be somebody else’s problem,” Stanley said.

One of the group’s scientific partners, the University of Virginia, is currently developing and will soon be testing a method to take PFAS out of hemp plants, according to Bryan Berger, a chemical engineering professor.

Berger declined to reveal what method will be tested but said that if successful, he and colleagues could publish results in early 2025.

Hemp, like other plant species containing toxic contaminants, cannot simply be burned, Berger said.

“That ends up creating airborne forms [of PFAS] that can end up in the atmosphere,” Berger said.

Hemp-based research related to PFAS extraction has been limited, as industrial hemp was only approved for agricultural use in 2018, and funding for such studies remains limited. But Berger and tribal partners recently scored a major funding source to expand their efforts and work toward long-term solutions.

Starting in 2025, the Mi’kmaq Nation, Stanley, Berger, the Connecticut Agricultural Experiment Station and Central Aroostook Soil and Water Conservation District will use a four-year, $1.6 million EPA grant to continue hemp planting at Loring and testing potential ways to extract PFAS from harvested hemp.

As part of the grant, the group will also test areas of the Aroostook River, a waterway that the Central Aroostook Soil & Water Conservation District has found to contain PFAS due to irrigation runoff from nearby crop fields. They will study hemp as a potential rotation crop for keeping PFAS from seeping into potatoes and other produce.

The agricultural studies will be a continuation of work that the conservation district has already begun, Berger said. His lab will test approximately 300 to 400 samples of water from the Aroostook River as well as potatoes and other crops to know the extent of PFAS contamination.

With colleagues from the Connecticut station, the group will study how PFAS moves through insect food chains using sample insects from Aroostook.

Berger credited the Mi’kmaq Nation and Stanley’s initial collaboration for being one of the first groups to study PFAS and hemp at the community level and bring attention to its potential.

“As a researcher, I have not seen a lot of people work on this until recently, so they’re way ahead of everybody else,” Berger said. “Our goal really is to help other tribes, farmers and rural communities who have been impacted [by PFAS].”