On a humid morning in Tianjin, China, researchers crouched in a public park with clippers and gloves, collecting leaves from hedges, grasses, and garden vegetables. Back in their lab, they did something few have thought of before: they washed the leaves, pulverized them, and searched inside.
What they found wasn’t entirely invisible — but it had long gone unnoticed.
Tiny shards of plastic, drifting in the air, had nestled inside the leaves themselves.
The new study published in Nature offers the strongest evidence yet that plants, including many of the vegetables we eat, can absorb airborne microplastics directly through their leaves. The finding shifts the focus of concern around plastic pollution from water and soil to a far more insidious route — the very air we breathe and the leafy food we eat.
The Plastic Pathway Through the Sky
The research team set up sampling sites around Tianjin, including a Dacron plastic factory, a public landfill, a park, and a university campus. They examined leaves from native plants and crop vegetables like maize and lettuce, using high-resolution imaging, spectroscopy, and chemical labeling to trace two common plastics: polyethylene terephthalate (PET) and polystyrene (PS).
The results were striking.
In the most polluted areas, plastic concentrations in leaves reached up to 10,000 nanograms per gram of dry weight — orders of magnitude higher than in less polluted environments like the university campus. In laboratory simulations, maize plants exposed to plastic-laden dust absorbed measurable amounts of PET in just 24 hours.
The pathway of entry is the same structures that allow plants to breathe—their stomata, tiny pores that open and close to exchange gases. Once inside, particles move through the plant’s internal water and nutrient highways, accumulating in vascular bundles and trichomes—hair-like structures on the leaf surface that seem to trap particles like miniature nets.
When researchers applied a chemical to force stomata shut, PET absorption dropped significantly, confirming that open stomata are crucial for microplastic uptake.
A New Chapter in the Plastisphere
Microplastics, defined as plastic particles under five millimeters, have already been found in human blood, lungs, and placentas. But this study suggests a new point of entry into the food web, starting with plants.
Concentrations of microplastics were 10 to 100 times higher in vegetables grown outdoors than in those grown in greenhouses. Older leaves — especially the outer ones often used in salads — carried the highest loads. These plastics were not just stuck to the surface. The team took painstaking steps to wash off all external contaminants before measuring internal accumulation.
And unlike soil or water, which require high concentrations of microplastics for uptake, the air carries a far more efficient delivery system. However, the efficiency of absorption is still low — around 0.05% — but the constant exposure of leaves to the open air and their longevity on the plant mean that over time, accumulation builds up.
What It Means for Us
This research opens uncomfortable questions. If we inhale airborne microplastics and now consume them in vegetables, how much are we truly exposed to? And what are the long-term health risks?
So far, the answers remain elusive. Scientists have not yet pinned down the threshold levels at which microplastics become harmful to human health. Studies suggest they can trigger inflammation, carry toxic chemicals, and potentially interfere with the gut microbiome — but these mechanisms are still under investigation.
The implications go beyond personal health. If plastic particles are moving freely through the atmosphere and accumulating in staple crops, they could be affecting plant physiology, soil ecology, and the animals that feed on vegetation.
Some scientists are calling for a reevaluation of agricultural practices, urban air quality standards, and even food safety guidelines. At the very least, this study suggests we should rethink how plants interact with the pollutants we produce.
