Washing Vegetables Won’t Remove The Plastic Particles Inside Them

PLYMOUTH, England — You’re at the kitchen sink, scrubbing a fresh radish. You trust that washing clears away dirt, bacteria, and maybe pesticide residue. But what if some contaminants are already locked deep inside the plant, in places no soap or rinse can reach?

That unsettling possibility is what researchers at the University of Plymouth set out to test. Their results show, for the first time, that plastic particles tens of thousands of times smaller than a human hair, or “nanoplastics,” can move past plants’ natural defenses and end up in the edible tissues people actually eat.

How Nanoplastics Cross Plant Defenses

Plants are not defenseless. Their roots are lined with a barrier called the Casparian strip, a waxy band that normally stops unwanted substances from moving into the plant’s water transport system. For years, scientists assumed this barrier would block particles as large as nanoplastics.

But the Plymouth team designed an experiment to settle the question. They grew radishes hydroponically and exposed only their thin underground roots to water containing radioactively tagged polystyrene nanoplastics. Because the edible red bulb and leafy shoots never touched the solution, any particles found in them had to have traveled internally through the plant.

This setup avoided a common flaw in earlier studies, where shoots or seeds touched the water and contamination could have come from the surface instead of uptake.

Following the Plastics’ Journey

After five days of exposure, researchers dissected the radishes and measured radioactivity to see where the plastics had gone. Out of all the particles in the water, about 4.4% ended up associated with the plants.

Breaking that down further:

• Roughly 65% of those particles stayed in the fine underground roots.
• About 25% traveled into the fleshy, edible bulb.
• Around 10% reached the green shoots.

That means about 1.1% of the total plastic exposure made its way into the part of the plant people actually eat. Scrubbing or peeling could never remove these particles, because they were embedded in the radish itself, not resting on the surface.

Why Washing Doesn’t Work

Traditional food safety advice like washing produce under running water, scrubbing where possible, and peeling if needed, remains effective for surface risks like bacteria or pesticide residue. But this study shows nanoplastics behave differently. Once inside the plant, they are absorbed into tissues through biological processes scientists are still working to fully understand. Possible routes include transport between cells or entry through tiny pores.

The important point for consumers is that these particles become lodged within the plant, well beyond the reach of rinsing or scrubbing.

What the Findings Mean for Food Safety

The Plymouth team compared their results to earlier work with another carbon-based nanoparticle, fullerene C60. That study also found particles accumulating in edible radish tissues, though it involved a different material rather than plastic. The researchers stress that results cannot be generalized across all plastics, since different polymers may interact with plants in very different ways.

Still, this new experiment demonstrates that polystyrene nanoplastics can cross a protective barrier once thought nearly impenetrable, and reach the edible tissues of a crop.

Real-World Questions and Limitations

The researchers are cautious about what these findings mean outside the lab. The concentration of plastics used in the experiment was chosen so they could be measured accurately. It was likely higher than what radishes would normally face, though the actual levels of nanoplastics in soils and hydroponic systems remain unknown.

The study also used only one type of plastic particle and a single plant species, tested over just five days. The roots were carefully washed in a solution proven to remove surface particles, but the study cannot entirely rule out the possibility that a fraction of the plastics stuck to outer tissues rather than being fully absorbed.

What seems clear is that plants lack the quick elimination systems animals use to expel unwanted particles. That could make crops more likely to retain nanoplastics over time.

Why This Matters for Consumers

Nanoplastics and microplastics have already been detected in soil, in water, and even in human blood. Scientists are still piecing together what health risks they might pose, but their presence inside edible crops opens a new question about how they move through food chains.

For consumers, the takeaway is not to abandon washing. Cleaning still matters for removing bacteria and chemical residues. But washing cannot touch this type of contamination in vegetables. Addressing nanoplastics in food will likely depend on reducing plastic pollution at its source, not on what happens at the kitchen sink.