This type of cannabis can suck "forever chemicals" out of the ground

Hemp, a variety of the plant Cannabis sativa, is often overshadowed by marijuana — a genetically distinct form of cannabis. Used for food, clothing, fuel, and plastics, it’s the seemingly more domestic member of the family.

However, new research suggests we should pay more attention to this nonpsychoactive substance. Hemp, scientists say, has an eco-friendly superpower: It can rid the environment of toxic chemicals.

Members of the Micmac (Mi'kmaq) Nation — a tribe indigenous to what’s now known as Canada’s eastern Maritime Provinces and parts of the northeastern United States — the activist group Upland Grassroots, and research scientists came together in 2019 to test methods for removing per- and polyfluoroalkyl substances (PFAS) from land located at the Loring Air Force Base. After years of lobbying and dispute, portions of the former bomber base were given back to the Aroostook Band of Micmacs in 2018.

On Tuesday, the eclectic team published a commentary reflecting on their work and progress in the journal Cell Press. The project, so far, is a success: Results suggest planting small fields of fiber hemp removed a primary type of PFAS at the polluted site, a chemical called perfluorooctanesulfonic acid (PFOS).

“Protecting the land is part of the Micmac beliefs,” Chief E. Peter Paul of the Micmac Nation said in the commentary. “Anything we can do to contribute to making the environment better, we want to be a part of.”

What you need to know first — The idea of removing toxic contaminants from the soil by planting certain plants is known as “phytoremediation.”

Hemp is “versatile in extracting many different kinds of chemicals from the soil,” Chelli Stanley, a member of Upland Grassroots, states in the commentary.

Previous research has also demonstrated industrial hemp can be effective in phytoremediation.

“Hemp phytoremediation has been previously used for other types of soil contaminants – mainly metals,” Sara L. Nason, one of the lead researchers on the project, tells Inverse. Nason is a scientist affiliated with the Connecticut Agricultural Experiment station.

Hemp, in turn, has been grown in other sites with significant amounts of environmental contamination such as Chernobyl, Nason says.

But little research has been conducted on the ability of hemp to specifically extract PFAS from the soil. PFAS are a group of man-made chemicals with potentially harmful effects on the human body, including increased cancer risk. They can be found in everything from drinking water to cleaning supplies.

PFAs are often referred to as “forever chemicals” for their ability to linger on in the environment — and human bodies — for years.

How they did it — One of the other common substances containing PFA is fire-fighting foam.

The Loring Air Force Base, formerly located in Aroostook County, Maine, used to serve as a firefighting testing ground. In a separate, earlier analysis, the US Air Force detected “concerning levels” of PFAS in groundwater at the site, but nothing was done to remove the chemicals.

“We received 800 acres from the United States Air Force, which included part of the Loring AFB,” Richard J. Silliboy of the Micmac Nation said in the commentary. “The part that we received was supposed to have been cleaned, but there’s still a lot of ground there that I believe is contaminated.”

Due to challenges with lack of funding and travel not being possible due to the pandemic, the scientists relied upon local indigenous volunteers to collect field samples. They also collaborated with the Upland Grassroots organization to develop a plan for local volunteers to plant hemp and collect soil samples that would stand up to scientific scrutiny.

What they discovered — Through this collaboration, the scientists were able to review the ability of fiber hemp to remove PFAS from the contaminated soil. Ultimately, they found concentrations of PFAS decreased in both hemp growth plots planted.

“Plants that take in more water and nutrients also tend to take in larger amounts of contaminants.”

Planting hemp makes for a particularly good way to clear the soil of contaminants because of its high water content and ability to grow quickly, Nason says.

“Plants that take in more water and nutrients also tend to take in larger amounts of contaminants,” she says.

Nason adds that plants “take up soil contaminants such as PFAS through their roots along with water and essential nutrients.”

These findings have not yet been peer-reviewed, though a research article published in 2020 by Nason and colleagues describes the process of how to remove PFAS from the Loring Air Force base land. However, the results are promising and the potential looms large.

“The application potential for this project is very exciting,” Paul reflects. “What other chemicals can hemp extract from the ground? Can we help make it a productive habitat again?”

Why it matters — The project is remarkable not only for its findings but also for its unique method of partnering scientists with passionate community members and activists.

It also speaks to the value of relying on the knowledge and passion of indigenous community members, who have a vested interest in protecting their land.

“We want to be sovereign, and keeping our sovereignty means protecting the earth,” Paul says.

In recent years, scientists have incorporated indigenous environmental practices to inform better wildfire stewardship as the climate crisis makes wildfires more severe and frequent.

This project in Maine is just the latest example of scientists working with and learning from indigenous collaborators to produce better scientific outcomes.

What’s next — Research on hemp phytoremediation and PFAs is still “in its early stages,” Nason says. Scientists are still figuring out how to work around three emerging challenges.

The first challenge is scientific: Since PFAs are so common in the environment, it can be hard to find sufficient “clean” PFAS-free samples to use as a control group.

“To have a complete phytoremediation study, we need more soil and plant samples,” Nason says.

The second challenge is more complex: It’s hard to get funding for partnerships between volunteer community members and scientists. And without funding, it’s difficult to expand these projects into additional communities.

These types of partnerships are necessary to create meaningful research that both benefits from community knowledges and moves science forward, the team argues in the commentary.

“The challenge I see is the possibility of not being able to do this on a scale that’s large enough to make a difference,” Paul writes.

The third challenge concerns the disposal of PFAS-contaminated hemp. Once in a plant, PFAS don’t naturally break down because of strong molecular bonds. Hemp has to be safely disposed of in order to prevent PFAS contamination of the environment.

It’s also very difficult to break down PFAS by either compost or incineration, Nason says. That’s why the volunteers at the Loring Airforce site bring PFAS-contaminated hemp to landfills to prevent runoff of these toxic chemicals into the community.

“It is not an ideal solution, but it at least helps to get the PFAS out of the Micmac land and keeps them from spreading,” Nason says.

It’s unclear whether we can turn the contaminated hemp into other materials, though a 2018 Rolling Stone article on hemp phytoremediation states “farmers have been cleared to sell harvested hemp fiber for industrial use” in Italy.

“We don’t yet know a lot about what happens with the PFAS once they enter the plants, and whether parts of the plant might be usable in products like fiber or building materials,” Nason says. “This is a topic we would we would like to investigate in the future.”

Editor’s note 7/23: This article has been updated to reflect the process of disposing of hemp containing PFAS.