Soil health is the foundation of thriving ecosystems and food systems. But what happens when our soils are tainted by “forever chemicals”-the notorious PFAS that resist breakdown and threaten food safety? Scientists are turning to plants for answers, exploring whether nature’s green powerhouses can help regenerate soil and tackle PFAS contamination.
PFAS are a large group of human-made chemicals found in everything from Topo Chico to firefighting foam. They’re called “forever chemicals” because they don’t break down easily, accumulating in water, soil, and living organisms-including us. Exposure to PFAS is linked to health problems like high cholesterol, immune suppression, developmental issues, and even cancer.
Can Plants Absorb PFAS from Soil?
Yes-certain plants can absorb PFAS from soil, through a process known as phytoremediation. But the effectiveness depends on the plant species, the type of PFAS, and environmental conditions
Key Findings:
- Hemp (Cannabis sativa): Hemp has shown promise in absorbing some PFAS, especially the smaller, more water-soluble types.
- Field trials at the former Loring Air Force Base showed that hemp could take up 10 out of 28 PFAS detected in soil. In the most successful plots, hemp removed up to approximately 2% of total PFAS from the soil, primarily accumulating these chemicals in its stems and leaves.
- Laboratory and greenhouse experiments confirm that hemp can absorb PFAS like perfluorobutanoic acid (PFBA) into leaves, stems, and flowers, while larger, less water-soluble PFAS such as PFOS and PFOA tend to remain in the roots.
- While hemp phytoremediation is not a comprehensive solution, it offers a promising approach to reducing PFAS levels in contaminated soils.
- Switchgrass
- Switchgrass has been explored as a candidate for phytoremediation of PFAS-contaminated soils, primarily because of its robust root system and ability to grow in marginal soils. Its extensive root network may help stabilize soil and potentially uptake or immobilize contaminants.
- Research indicates that switchgrass can absorb some PFAS compounds, but uptake levels tend to be lower compared to plants like hemp or leafy greens. The majority of PFAS absorbed by switchgrass often remains in the roots rather than translocating to shoots or leaves. This characteristic could be beneficial by limiting PFAS entry into the above-ground biomass, reducing risks if the plant is harvested or grazed.
- Leafy Greens (lettuce, kale, celery): These plants tend to accumulate higher levels of PFAS, particularly the short-chain varieties.
- Leafy greens are known to accumulate high levels of PFAS, especially short-chain varieties, in their edible leaves. However, this high uptake is considered a food safety concern rather than a remediation advantage, since these crops are meant for human consumption and could introduce PFAS into the food chain.
The Limits of Vegetation Based PFAS Cleanup
While the idea is promising, phytoremediation isn’t a comprehensive solution for PFAS contamination.
- Partial Removal: Even the best systems remove only a portion of PFAS-sometimes up to 34% for short-chain types after 90 days, but often much less for long-chain PFAS, which cling tightly to soil.
- Slow Process: It can take multiple planting cycles to see meaningful reductions.
- Disposal Dilemma: Plants that absorb PFAS become hazardous waste themselves. There’s currently no safe way to compost or naturally degrade these chemicals after harvest.
- Not All PFAS Are Equal: Short-chain PFAS are more easily absorbed and moved into plant tissues, while long-chain PFAS mostly stay in the roots or soil.
Are PFAS-Absorbing Plants Safe to Eat?
No. Plants used to clean up PFAS-like hemp and leafy greens grown in contaminated soil-are not safe for human or animal consumption. They can concentrate PFAS in their tissues, posing health risks if eaten.
Even homegrown produce in contaminated areas can add to your PFAS exposure, especially if you eat a lot of leafy greens.
Safety Tips:
- Test your soil and water for PFAS before planting edibles.
- Use clean soil in raised beds if contamination is a concern.
- Limit consumption and distribution of produce from known PFAS-affected areas.
- Never consume plants grown specifically for PFAS cleanup.
Innovations on the Horizon
Researchers are experimenting with ways to boost plant uptake of PFAS, one method being explored pairs plants with fungi that can break down PFAS. Hybrid approaches utilizing fungi, microbes, and vegetation may one day make phytoremediation more effective and safer.
The Bottom Line
Plants like hemp and leafy greens can help reduce PFAS in soil, but they cannot eliminate all PFAS. Phytoremediation is best used alongside other cleanup methods, like soil washing or containment.
Safe disposal of contaminated plants remains a critical challenge.
