Microplastics Can Change How The Body Responds To Allergens, Study Finds

Every year, the conversation around seasonal allergies sounds pretty much the same. People blame the pollen count. The weather. The unusually warm winter. Maybe climate change.

But what if pollen isn't acting alone?

Over the past few years, scientists have discovered microplastics virtually everywhere they've looked: in oceans, soil, drinking water, blood, arteries, lungs, and even the brain. Finding them is no longer the surprising part. The bigger question now is what these particles are doing once they get there.

A new study1 published in Toxicology and Applied Pharmacology offers one possible clue. Researchers found that tiny PET microplastics, the type commonly shed from plastic bottles, food packaging, carpets, and synthetic clothing, were able to linger in the lungs and alter immune responses. When combined with ragweed pollen, one of the most common seasonal allergens, airway inflammation became even more pronounced.

For the study, researchers focused on polyethylene terephthalate (PET), one of the most widely used plastics in modern life. PET is found in beverage bottles, food packaging, synthetic fabrics, carpets, and many other everyday products. Over time, these materials break down into microscopic particles that can become airborne and inhaled.

The researchers exposed mice to respirable PET microplastics, meaning particles small enough to reach deep into the lungs. Some mice were exposed to microplastics alone, while others were exposed to both microplastics and ragweed pollen, a common trigger of seasonal allergies.

One of the first things researchers noticed was persistence. The microplastic particles remained detectable in lung tissue for at least 14 days after exposure. They also appeared to accumulate within immune cells called macrophages, which help clear foreign particles from the lungs.

What surprised researchers was that the microplastics didn't need pollen to trigger a reaction. On their own, the particles caused inflammation in the airways and attracted immune cells into the lungs.

But when ragweed pollen was added, the response became even stronger.

Compared to pollen exposure alone, certain doses of microplastics appeared to intensify airway inflammation. The particles also changed how the immune system responded to the allergen, influencing antibody production and other immune signaling pathways.

Airborne PET particles are released from synthetic clothing, upholstery, carpets, food packaging, and household dust. Researchers note that inhalation may be one of the primary ways people encounter these particles.

It's easy to read headlines about microplastics and feel like they're impossible to avoid. In many ways, that's true. But what studies like this can do is help us understand where risks may exist and where practical interventions might make a difference.