Study: Intercropping Doesn't Prevent PFAS Uptake — Lettuce Leaves Show High Contamination Risk

New research from scientists at the University of Maine shows that intercropping — the practice of growing different crops side-by-side — does not reliably reduce plants' uptake of per- and polyfluoroalkyl substances (PFAS), the persistent chemicals often called "forever chemicals." The study, published in the journal Environmental Advances, tested lettuce, tomato and tall fescue grown in PFAS-contaminated soil and found outcomes varied by chemical type and plant species.

Key findings

Chemical behavior differs: Long-chain PFAS tended to concentrate in plant roots, while short-chain PFAS were more likely to appear in leaves. In contrast, lettuce accumulated both long- and short-chain PFAS at higher concentrations in its edible leaves than in its roots.

Intercropping effects were inconsistent: Most crop pairings increased PFAS concentrations in the edible portions of plants. The only clear exception was that tomato fruits showed lower PFAS levels when grown alongside lettuce.

"This study shows that there is no one-size-fits-all recommendation or policy for farmers dealing with PFAS contamination," said Alex Scearce, the University of Maine Ph.D. student who led the research. He noted that soil properties, plant species and PFAS chemistry interact in complex ways that require further study on working farms.

Health and practical implications

PFAS are used in many consumer products and can persist in the environment for decades or longer. They can accumulate in the human body and have been associated with health risks such as liver effects, thyroid disruption and some cancers. The lettuce results are particularly concerning because they indicate a direct route for PFAS to reach consumers via leafy vegetables.

While fully avoiding PFAS exposure is difficult, individuals can take practical steps to reduce some sources of intake. Simple measures include minimizing use of nonstick cookware (consider a well-maintained cast-iron skillet), checking product labels for PFAS-free claims, and supporting policies and retailers that phase PFAS out of food packaging.

What's next

The researchers emphasize that targeted, evidence-based guidance is needed for farmers managing PFAS-contaminated fields, rather than broad recommendations. Future research should test more crop types, soil conditions and real-world farming systems to develop practical mitigation strategies.