Microplastics are now found almost everywhere in the environment, and new research reveals they may have serious effects on human health. A study presented at the ATS 2025 International Conference has shown that inhaling microplastics weakens a key part of the lung’s immune defense system.
The study found that microplastics reduce the activity of pulmonary macrophages. These are a type of white blood cell in the lungs that help protect the body by removing harmful substances. When these cells are weakened, the immune system may become less effective, increasing the risk of diseases, including cancer.
“It’s eye-opening. Microplastics might not be the most dangerous particles we inhale, but they are definitely not harmless,” said Dr. Adam Soloff, associate professor of cardiothoracic surgery at the University of Pittsburgh and the study’s lead author. “Once inhaled, microplastics can travel through the lungs and affect other parts of the body. This could lead to damage in many organ systems.”
How the Study Was Conducted
Researchers examined the effects of polystyrene microplastics on macrophages in two ways. First, they exposed cultured macrophage cells to microplastics of different sizes and concentrations. Then, they exposed live mice to airborne microplastics to observe real-world effects.
Within just 24 hours, the researchers saw that macrophages had trouble performing phagocytosis — the process of surrounding and absorbing harmful bacteria. Microplastic particles were also found in the liver, spleen, colon, and even in small amounts in the brain and kidneys up to a week after exposure.
Possible Treatment Option
The study also tested a potential treatment. Researchers found that Acadesine, a drug that activates AMP kinase, was able to partially restore macrophage function after exposure to microplastics.
Dr. Soloff said he was surprised by the results. “At first, I thought the macrophages would simply digest the plastics. But not only did they struggle to break them down, they also held onto these particles over time,” he said.
The findings could lead to future therapies. “In places with poor air quality, having an affordable treatment to boost lung immune function could help fight rising lung disease rates,” Dr. Soloff added.
Next Steps
The research team plans to study lung tissues from human patients to see how microplastics affect real-life lung health. Their goal is to identify biomarkers for diseases like lung cancer, which could help with early screening and treatment.
