Inhaled microplastic particles can remain in the lungs for at least 14 days and trigger inflammation linked to allergies, a new study in mice reveals.
Nearly ubiquitous tiny plastic particles under 5mm in size have been shown to pose a threat to environmental and public health, with their exposure linked to cancer, heart attacks, and reproductive problems.
Early studies have shown that in tissues where they accumulate, microplastic particles can induce inflammation, DNA damage, cell ageing, and hormone disruptions.
However, very little is yet known about their effects on the immune system.
Now, a new study has assessed the effects of tiny particles of PET, one of the most widely used plastics worldwide, in mice.
Researchers from the Medical University of Vienna found that after a single administration of PET microplastics, the tiny particles remained detectable in the lungs for at least 14 days.
Their presence in the lungs was also accompanied by inflammation and an increased presence of lymphocytes and eosinophils – immune cells that are involved in allergic reactions.
“Inhaled PET microplastics induce dose-dependent airway inflammation,” scientists wrote in the study published in the Journal of Hazardous Materials Advances.
“PET microplastics remained detectable in the lung for 14 days, and induced airway inflammation with lymphocyte and eosinophil recruitment,” they wrote.
Combined with ragweed pollen, a commonly inhaled allergen, inflammation became exacerbated, the study warned.
Scientists found that the PET particles exacerbated the inflammation and influenced the body’s defensive response against the allergen.
"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 Michelle Epstein, an author of the study from the Medical University of Vienna.
The study, according to researchers, provides important insights into the potential immunological effects of microplastics.
Currently, the reported airborne levels of PET have reached about 135-158 nanograms per cubic metre of air in cities.
Assuming that an adult inhales about 10–20 cubic metres of air daily, this may correspond to about 1–3 micrograms of microplastics inhaled, researchers say.
“Together, these findings identify PET MPs as biologically active particles that alter airway inflammation and immune responses in a dose- and context-dependent manner,” they wrote.
While the results were obtained in mouse models and may not be directly extrapolated to humans, scientists hope the health and environmental burden of microplastics will be investigated in further studies.
“These findings support the inclusion of immune endpoints while emphasising the need for cautious extrapolation to real-world exposure scenarios,” researchers wrote.
“In summary, PET microplastics persist in the lung, induce airway inflammation, and modulate immune responses in a dose, timing, and context-dependent manner,” they concluded.
