Scientists discovered why certain toxic chemicals called PFAS accumulate differently in fruits like tomatoes. They found that chemicals with a specific type of molecular structure (sulfonic acid) barely make it into the fruit, while similar chemicals with a different structure (carboxylic acid) build up much more. In tomato plants, one type of PFAS reached levels 500 times higher in fruit than the other type. This matters because it means some PFAS chemicals may pose less risk to humans through the food we eat, though both types are concerning environmental pollutants.

The Quick Take

  • What they studied: How different types of PFAS chemicals (toxic ‘forever chemicals’ that don’t break down in nature) move through tomato plants and end up in the fruit we eat
  • Who participated: Tomato plants grown in controlled laboratory conditions with different PFAS chemicals added to their growing water
  • Key finding: One type of PFAS (PFPeA) accumulated to 34.83 micrograms per gram in tomato fruit, while another type (PFBS) only reached 0.07 micrograms per gram—nearly 500 times less. The chemical structure of PFAS determines how much gets into the fruit.
  • What it means for you: If you eat tomatoes or other fruits, the type of PFAS chemical matters for your exposure risk. However, this doesn’t mean tomatoes are safe to eat—it just means some PFAS chemicals may pose less risk through food than others. More research is needed on real-world conditions.

The Research Details

Researchers grew tomato plants in a controlled water solution containing two different PFAS chemicals, one at a time. They measured how much of each chemical accumulated in different plant parts (roots, stems, leaves, and fruit) over an entire growing season. They also did special experiments where they tracked where chemicals moved after being absorbed by leaves, to understand the pathways chemicals take through the plant.

The study used tomato plants as a model because they’re commonly eaten and easy to study in laboratories. By changing only the chemical structure of the PFAS (keeping everything else the same), researchers could identify which part of the molecule’s structure determines how much reaches the fruit.

This approach is like comparing two similar cars that differ only in their engines to figure out which part affects fuel efficiency—by keeping everything else constant, you can pinpoint what matters.

Understanding why some chemicals accumulate in food and others don’t helps scientists predict which PFAS chemicals pose the biggest food safety risks. This information can guide environmental protection efforts and help identify which chemicals to prioritize for regulation. It also reveals biological barriers in plants that naturally limit some chemical accumulation.

This is a controlled laboratory study, which means conditions were carefully managed and results are reliable for the specific setup tested. However, real-world farms have different soil types, weather, and growing conditions that could change results. The study used tomato plants as a model, so findings may not apply equally to all fruits and vegetables. The research was published in a respected environmental science journal, suggesting it underwent peer review by other experts.

What the Results Show

When tomato plants were exposed to PFPeA (a PFAS with carboxylic acid structure) throughout their growing season, the fruit accumulated very high levels—up to 34.83 micrograms per gram. In contrast, when exposed to PFBS (a PFAS with sulfonic acid structure), fruit levels were barely detectable at only 0.07 micrograms per gram.

When researchers tracked where chemicals went after being absorbed, they found that 65% of PFPeA that entered the plant during the seedling stage eventually moved to the fruit as the plant matured. For PFBS, almost none (99.99%) stayed stuck in the leaves and never reached the fruit at all.

When scientists directly fed PFAS to leaves (simulating how plants might absorb chemicals from air or water on leaves), 89.55% of PFPeA moved into the fruit within the plant’s transport system. PFBS, however, couldn’t be detected in the fruit even when fed directly to leaves. This showed that the plant’s transport system actively moves PFPeA to fruit but blocks PFBS from traveling there.

The research identified that the main barrier preventing PFBS from reaching fruit is at the roots—the chemical struggles to move out of roots into the rest of the plant. Additionally, even when PFBS does get absorbed, the plant preferentially deposits it in leaves rather than moving it toward fruit. These two mechanisms work together to keep PFBS out of the edible part of the plant. The study suggests that the sulfonic acid chemical structure is recognized by the plant as something to keep out of fruits, possibly because it’s more water-soluble and the plant’s transport system treats it differently.

Previous research had observed that PFAS chemicals with sulfonic acid structures accumulate less in fruits than those with carboxylic acid structures, but scientists didn’t understand why. This study provides the first detailed explanation of the mechanisms involved. The findings support the idea that chemical structure is the key factor, not other variables like how much the plant needs the chemical or how toxic it is to the plant.

This study was conducted in controlled laboratory conditions with tomato plants grown in water solutions, not in real soil. Real-world farms have different soil types, microorganisms, and environmental conditions that could change how much PFAS accumulates in fruit. The study only tested two specific PFAS chemicals, so results may not apply to all PFAS types. Additionally, the study used relatively high PFAS concentrations (0.80 micromolar) to ensure measurable results, which may be higher than typical environmental exposure. The findings are specific to tomato plants and may differ for other fruits and vegetables.

The Bottom Line

Based on this research (moderate confidence): The chemical structure of PFAS matters significantly for food safety risk. PFAS chemicals with sulfonic acid structures appear to pose less risk through fruit consumption than those with carboxylic acid structures. However, this doesn’t mean foods are safe from PFAS—it means some types may be less problematic than others. Continue following general food safety guidelines and regulatory standards. If you’re concerned about PFAS exposure, focus on reducing consumption of foods known to accumulate high levels of PFAS and consider using water filters if PFAS has been detected in your local water supply.

This research matters most to: Environmental regulators deciding which PFAS chemicals to prioritize for restrictions; farmers and food producers concerned about contamination; people living near PFAS-contaminated water sources; parents concerned about children’s food safety; and public health officials developing guidelines. This research is less immediately relevant to people in areas without known PFAS contamination, though PFAS is increasingly detected globally.

This research describes how PFAS accumulates over an entire growing season (months). If PFAS exposure is reduced, it would take a similar timeframe for plants to stop accumulating new chemicals, though existing contamination in soil would persist for years or decades since PFAS doesn’t break down naturally.

Want to Apply This Research?

  • Track produce sources and types consumed weekly, noting whether items are from local sources, farms, or stores. If concerned about PFAS, note which produce types you consume most frequently, as this helps identify where your dietary exposure might be highest.
  • If you have access to water quality reports showing PFAS contamination in your area, consider: installing a water filter certified to remove PFAS, diversifying your produce sources, and reducing consumption of produce grown in contaminated water. Track which changes you implement and any health improvements you notice.
  • Monthly: Review local water quality reports for PFAS detection. Quarterly: Assess your produce consumption patterns and sources. Annually: Check if new PFAS regulations or guidelines have been issued in your region that might affect food safety recommendations.

This research describes laboratory findings in tomato plants and should not be interpreted as definitive guidance for food safety in real-world conditions. PFAS chemicals are regulated differently by various countries and regions. Consult local health authorities and EPA guidelines for current recommendations on PFAS exposure and food safety. If you have specific health concerns about PFAS exposure, speak with your healthcare provider. This article is for educational purposes and does not replace professional medical or environmental health advice.