Tiny fragments of plastic are now found almost everywhere in our environment—from the air we breathe to the food we eat. While concerns about their impact on ecosystems have grown for years, scientists are only beginning to understand how these microscopic particles affect human health. New research led by the Medical University of Vienna suggests that microplastics may do more than accumulate in the body—they may actively alter the immune system and worsen allergic inflammation.
In a study published in the Journal of Hazardous Materials Advances, researchers investigated the effects of polyethylene terephthalate (PET), one of the world’s most commonly used plastics. PET is found in everyday products such as beverage bottles, food packaging, textiles, and even certain medical materials. Using a mouse model, the team examined how PET microplastics of different sizes and concentrations influenced immune responses.
The findings revealed that after a single exposure through the respiratory tract, medium-sized PET microplastic particles remained in the lungs for at least two weeks. During that time, the particles triggered an inflammatory response marked by increased numbers of lymphocytes and eosinophils—immune cells closely linked to allergic reactions and asthma.
The effects became even more striking when the mice were simultaneously exposed to ragweed pollen, a common environmental allergen. Under certain conditions, the combination of microplastics and pollen intensified airway inflammation, suggesting that microplastics may amplify the body’s response to allergens. Additional experiments showed that when PET microplastics were introduced together with other allergens, they altered immune activity throughout the body, increasing inflammation and changing the production of antibodies directed against those allergens.
“Our study shows that PET microplastics do not simply remain in the body, but actively influence immune responses involved in the development and exacerbation of allergic reactions and inflammation,” said lead investigator Michelle Epstein of the Experimental Allergy Laboratory at the Medical University of Vienna.
Although the study was conducted in mice and the findings cannot be directly applied to humans, the results provide important clues about the potential health consequences of the growing microplastic burden in our environment. The researchers stress that further studies are needed to determine how real-world exposure to microplastics may affect human immune function and allergic disease. As evidence continues to emerge, these tiny particles are proving to be much more than an environmental concern—they may also represent an important public health challenge.
More information: Sahar Kazemi et al, Respirable polyethylene terephthalate microplastics modulate airway inflammation and immune responses in murine allergen co-exposure models, Journal of Hazardous Materials Advances. DOI: 10.1016/j.hazadv.2026.101223
Journal information: Journal of Hazardous Materials Advances Provided by Medical University of Vienna
