If the world getting hotter and wetter wasn’t enough, another environmental crisis is beginning to rear its ugly head. PFAS, per- and polyfluoroalkyl substances, are everywhere. They’re in your raincoat, your non-stick pan, and increasingly, your drinking water. These synthetic chemicals, dubbed “forever chemicals” because they don’t break down naturally, are now contaminating soil and water systems across the UK. A recent BBC investigation revealed the scale of the problem, with PFAS detected in water supplies and agricultural land throughout the country.
The UK Environment Agency estimates that PFAS contamination affects thousands of sites nationwide, from former fire brigade training grounds to industrial areas. Traditional cleanup methods, excavation and incineration, are expensive, disruptive, and often impractical for large contaminated areas. This has sparked interest in a potentially cheaper, greener alternative: using plants to suck the chemicals out of the soil. Enter, once again, the wondercrop that is hemp.
The forever chemical problem
PFAS are a family of over 4,000 synthetic chemicals that have been used since the 1940s in everything from firefighting foam to food packaging. Their superpower – extreme resistance to heat, water, and degradation – is also their curse. Once released into the environment, they persist for decades, if not centuries.
These chemicals don’t just hang around; they accumulate in human bodies and the food chain. Peer-reviewed studies have linked PFAS exposure to serious health impacts, including increased cancer risk, immune system disruption, thyroid disease, and reproductive problems. Research published in Environmental Health Perspectives found that even low-level exposure can affect immune function, making vaccines less effective.
The problem is getting worse. As awareness grows, testing reveals PFAS contamination in previously unknown sites. Traditional remediation – digging up contaminated soil and either incinerating it at extreme temperatures or storing it in specialist facilities – can cost millions of pounds per site. For large agricultural areas or widespread contamination, these methods simply aren’t viable.
How hemp might help
Hemp (Cannabis sativa) has form when it comes to cleaning up contaminated sites. The plant has been successfully used to remove heavy metals like cadmium and lead from polluted soil, a process called phytoremediation. Its deep root system, rapid growth, and ability to produce large amounts of biomass make it particularly suited to the task.
But PFAS are different from heavy metals. These synthetic compounds are more complex, with varying chain lengths and chemical structures. Some are more readily absorbed by plants than others. The question is whether hemp can handle them.
Hemp showed promise as a PFAS solution in a 2024 peer-reviewed study by Sara Nason and colleagues, published in Chemosphere. The researchers tested the ChinMa hemp variety on PFAS-contaminated soil and found that the plants absorbed ten different PFAS compounds, with greater accumulation in leaves than stems.
The results were modest but consistent: approximately 2% of PFAS was removed from the soil in a single growing season, primarily in the root zone. The study also revealed that hemp preferentially absorbs shorter-chain PFAS (those with three to four perfluoroalkyl carbons) rather than longer chains.
Earlier work by the Micmac Nation in Maine demonstrated the concept’s viability. Their 2020 pilot project used hemp on contaminated soil from a former Air Force base, showing what researchers described as “conservatively promising” results over two years.
But it was a recent Belgian trial, at Campus Vesta in Ranst, which produced the most promising results by combining hemp phytoremediation with biotechnology. This project, treating contaminated soil at a firefighting training site, achieved an incredible 67% PFAS reduction in just four months.
Here, nature was used alongside natural soil additives developed by biotech company C-biotech. These additives work in two ways: they boost the growth of hemp and willow trees planted on the contaminated site, while simultaneously increasing the bioavailability and mobility of PFAS in the soil. The additives facilitate “chain shortening” of PFAS molecules, breaking down the hard-to-absorb long-chain compounds and making them more accessible for plant uptake. This accelerated phytoremediation approach reportedly speeds up PFAS removal by up to 30 times compared to standard methods.
- Before and after heat map showing reduction of PFAS in the Campus Vesta trial – Source: Earth+
In the trial, initial PFAS levels ranged from 0.5 to 29 μg/kg – well above Belgium’s legal limit of 3.85 μg/kg for certain land uses. Within four months, PFAS concentrations in harvested plant biomass reached up to 380 μg/kg, demonstrating substantial extraction from the soil. “The hemp was so successful here that two-thirds of the treated area has been virtually remediated, and even in the remaining third, the PFAS concentration is too low for further research,” the project’s manager, Erik De Bruyn, said.
The disposal dilemma
While phytoremediation is promising in the fight against these pollutants, there is another challenge to overcome in the process: once hemp has absorbed PFAS from the soil, you’re left with PFAS-containing bio-material. These forever chemicals haven’t gone away, they’ve just been moved from soil to plant.
However, the problem can be solved, and in some ways, has benefits. Hemp stems, which don’t accumulate PFAS in the same way as leaves, can be safely repurposed for building materials or fibre products. The leaves, where PFAS concentrates, must be destroyed in a controlled process to prevent the chemicals from re-entering the environment.
One avenue is hydrothermal liquefaction (HTL) – essentially pressure-cooking the contaminated biomass to break down PFAS compounds. The Nason study tested this approach and found it could degrade PFAS residues, but researchers expressed concerns that the process requires significant energy and specialist equipment.
In the Campus Vesta trial, the contaminated biomass underwent hydrothermal treatment to destroy the PFAS and produce biochar, creating a “circular, carbon-negative” remediation solution.
The limitations
While hemp is once again proving to be something of a miracle crop from clearing up human mistakes, we’re not quite ready to soak up all the PFAS by planting a few crops.
With conservative results showing a 2% removal rate per growing season, speed could be an issue. For significantly contaminated sites, the timeline could stretch into decades. Even the most optimistic projections acknowledge you’d need multiple growing cycles to achieve meaningful remediation – and that’s assuming conditions remain consistent year after year.
Hemp can clean up the mess we’ve made, but it won’t solve the problem if we keep adding PFAS to consumer products and industrial processes
Then there’s the selectivity problem. Hemp doesn’t treat all PFAS equally. It preferentially absorbs shorter-chain compounds, while the longer-chain varieties – which are equally problematic – are less readily taken up. This means a site contaminated with multiple PFAS types could end up with patchy results. If additives aren’t used, like in the Belgian trial, some chemicals are reduced while others remain stubbornly in place, kicking the problem further down the line.
It’s also hard to know how the hemp solution would scale. All the successful trials to date have been small-scale, test plots and controlled environments. Whether this approach maintains its effectiveness across hectares of farmland or sprawling industrial sites is anyone’s guess. Different soil types, varying climate conditions, and local environmental factors could all throw a spanner in the works.
Will hemp solve the UK’s PFAS problem?
Hemp phytoremediation for PFAS isn’t a miracle solution, but it isn’t hyperbole either. The science shows it works, just like it has for heavy metals. Hemp has even been called on to remove radiation in the fields surrounding the nuclear disaster at Chernobyl.
For the technology to become viable in the UK, several things need to happen. More large-scale field trials are needed to understand how hemp performs across different soil types, contamination levels, and growing conditions. The UK needs investment in HTL or similar disposal infrastructure to process contaminated biomass safely. And regulatory frameworks must be changed to lift prohibitive restrictions on hemp crops.
Most importantly, we need to prevent new PFAS from entering the environment in the first place. Hemp can clean up the mess we’ve made, but it won’t solve the problem if we keep adding PFAS to consumer products and industrial processes. Real progress requires both remediation and prevention.
The forever chemical crisis won’t be solved by hemp alone. But as part of a broader strategy, this ancient crop might once again be the answer to a persistent environmental challenge we’ve created for ourselves.
